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THE

VOYAGE OF H.M.S. CHALLENGER.

ZOOLOGY-VOL XXVIII.

REPORT

SCIENTIFIC RESULTS

^

~r .

OF THK

VOYAGE OF H.M.S. CHALLENGER

DURING THE YEARS i 8 7 3-7 6

UNDER THE COMMAND OF

Captain GEORGE S. NARES, R.N., F.R.S.

AND THE LATE

Captain FRANK TOURLE THOMSON, R.N.

PREPARED UNDER THE SUPERINTENDENCE OF
THE LATE

Sir C. WYVILLE THOMSON, Knt., F.R.S., &c.

RBGIUS PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF EDINBURGH
DIRECTOR OF THE CIVILIAN SCIENTIFIC STAFF ON ROARI)

AND NOW OF

JOHN MURRAY, LL.D.. Ph.D., &c.

ONE OF THE NATURALISTS OF THE EXPEDITION

Zoology— Vol. XXVIII.

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CONTENTS.

Report on the SiphonophorjE collected by H.M.S. Challenger during the

years 1873-1876.

By Ernst Haeckel, M.D., Ph.D., Hon. F.R.S.E., &c, Professor of Zoology

in the University of Jena.

(The Manuscript was received in Instalments between 8th February and

5th July 1888.)

7 iiOO

t

EDITORIAL NOTE.

During the voyage of the Challenger, species of Siphonophorse were con-
tinually under observation in the living condition, both on the surface
of the ocean and in tanks on board the vessel ; none of the naturalists,
however, made any special study of this interesting and complicated
group of animals ; the specimens collected were merely preserved with
as much care and skill as was possible in the circumstances.

Probably no class of marine organisms presents, in general, greater
difficulties in the way of examination than the Siphonophorse, and these
difficulties are increased many fold when the naturalist has to deal with
collections preserved in alcohol and other media, which contract and distort
the specimens. Indeed it was essential that any naturalist who would
undertake a successful examination and interpretation of these varied
forms should himself have investigated these organisms during many
years in the hiving state.

Professor Haeckel, through his long-continued and elaborate investi-
gations of living Siphonophorae and Medusa? in the Mediterranean, Indian,
and Atlantic Oceans, was in a very special manner fitted to undertake such
a task, and it must be regarded as fortunate that he should have been
willing to undertake the work on condition that some of his own unpublished
observations should be incorporated.

This important and masterly Report has thus become a Monograph of
the whole class, more complete than any hitherto published ; the classifi-

viil THE VOYAGE OF H.M.S. CHALLENGER.

cation has been reformed and placed on a new basis. The new order,
Auronectffi, discovered by the Challenger in the depths of the ocean,
is particularly interesting to naturalists.

The Introduction, giving a general account of the morphology of the
order, was translated from the German Manuscript by Mr. J. Arthur
Thomson, M.A., F.R.S.E. All the remaining part of the Report was written
by Professor Haeckel in the English language.

This Report on the Siphonophoile forms Part LXXVII. of the Zoological
Series of Reports, and consists of 383 pages and 50 chromo-lithographic
plates.

John Murray.

Challenger Office, 32 Queen Street,
Edinburgh, October 13, 1888.

THE

VOYAGE OF H.M.S. CHALLENOEE.

ZOOLOGY.

REPORT on the Siphonopiior^e collected by H.M.S. Challenger during
the Years 1873-76. By Ernst Haeckel, M.D., Ph.D., Hon. F.R.S.E.,
Professor of Zoology in the University of Jena.

PEEFACE.

The Sipkonopkorse collected by tke Ckallenger during ker cruise round the world
were kanded to me for investigation in 1879. Tke examination of this material,
among which were to be found many new and remarkable types (especially abyssal
forms), led me to recommence my study of the organisation and development of
tke wkole class, wkick kad been interrupted for more tkan ten years. During a
residence of tkree months at Puerto del Arrecife, tke karbour of Lanzerote in tke
Canary Islands, December 18G6, January and February 1867, I kad tke opportunity
of becoming acquainted witk nearly all tke typical forms of tkis most attractive group
of animals. Tke facts wkick I tken discovered regarding tke curious, but till tben
little known, ontogenesis of tkese Acalepks, were embodied in a prize essay publisked
by tke Gesellsckaft fur Kunst und Wissensckaft in Utreckt.1 I tken intended to
follow up tkis embryological memoir witk a more extensive comparative anatomical
one, or if possible a Monograpb, in wkick also tke systematic arrangement of tke
Sipkonopkorse skould be subjected to a tkorougk revision, and tke very intricate
literature of tkis class critically elucidated. Tke completion of tkis sckeme was,
kowever, deferred owing to various external kindrances, and tke rick material collected
at Lanzerote remained for tke most part unpublisbed.

1 Ziir Entwickelungsgeschichte der Siphonophoren, Utrecht, 1869, 14 plates.
(ZOOL. CHALL, EXP. — FART LXXVII. — 1888.) Hhhh a

ii THE VOYAGE OF H.M.S. CHALLENGER.

In the meantime I found many opportunities of continuing my researches into the
Siphonophorse during the numerous journeys which I undertook for the purpose of
completing my System der Medusen, and to which I made some reference in 1879 in
the preface to that monograph. I also collected much valuable material in the
different museums which I visited for the same purpose. A further supply of
specimens, and among them many new and instructive forms, were received from
various travellers, and notably from Captain Heinrich Rabbe of Bremen. Lastly my
journey to India furnished me with a long wished-for opportunity of becoming
acquainted with the rich though little known Siphonophoral fauna of the Indian Ocean ;
on the journey out to Ceylon (via Bombay), on my return home (via Socotra), and
especially in the expeditions which I made from Belligemma and Matura, I observed a
number of new genera, some of which were exceedingly interesting (November 1881 to
March 1882). At the same time I was able to extend my earlier observations upon the
development and metamorphosis of the Siphonophorse.

Valuable systematic contributions were also derived from the study of the excellent
original drawings and the manuscripts of Mertens, of which Brandt gave a short
account in 1835. I am highly indebted to Professor Alexander Strauch in St. Petersburg
for the opportunity of examining these drawings which Mertens took in 1827 from living
Siphonophorse in the North Pacific, and which, unfortunately, have never been published;
they are among the best and most lifedike representations of the class that have ever
been produced.

I take this opportunity of expressing my best thanks to those gentlemen who have
assisted me in this investigation, especially to those travellers and directors of museums
who have furnished me with material. By their aid I have been enabled to extend our
knowledge of this group, and by the discovery of new morphological types to bring it to
a certain degree of completeness. I am especially indebted to my honoured friend,
Dr. John Murray, who with the greatest liberality offered to me all the Sipkonophorze
collected by himself, and gave me permission to incorporate my own rich materials
in this Monograph. My sincerest thanks are due also to the excellent artist, Mr.
Adolph Gdtsch, who, aided by his morphological interest and unwearying care, executed
the chromo-lithographic Plates of this Report with such perfection, that they will give
a complete idea of this most wonderful class of animals.

CONTENTS.

PREFACE,

GENERAL INTRODUCTION,

DESCRIPTION OF THE FAMILIES, GENERA, AND
Order I. DiscoNECTiE,

Family I. Discaliib , .

Family II. Porpitidre, .

Family III. Velellidae, .

Order II. Calyconect,e,

Family IV. Eudoxida;, .
Family V. Ersseidas,

Family VI. Monopliyid.r,
Family VII. Diphyidas,

SPECIES,

Family

VIII. Desmopliyidie,

Family

IX. Polypliyidae,

Order III. Physonect^e,

Family-

X. Circalidae, .

Family

XL Athoridw, .

Family

XII. Apolemidae,

Family

XIII. Agalmidae, .

Family

XIV. Forskalidse,

Family

XV. Nectalidas, .

Family

XVI. Discolabida?,

Family

XVII. Aiithophysida-,

Order IV. Auroxectj:, .

Family

XVIII. Stephalidse,

Family

XIX. Rhodalida?,

Order V. Cysto.nect.e, .

Family

XX. Cystalidee, .

Family

XXI. Rhizophysidse,

Family

XXII. Salacidse, .

Family XXIII. Epibulidas,

Family

XXIV. Physalidse,

BIBLIOGRAPHY OF THE SIPHONOPHOR/E,
LIST OF FAMILIES, GENERA, AND SPECIES
GLOSSARY, ....

STATISTICAL SYNOPSIS,

PACE

i

25

26
41
51
70

89

103

121
125
141
167
173

184

196
200
204
213
236
249
255
268

281
296
300

305
314
317
329
332
338

353

357

373

380

GENERAL. INTRODUCTION.

THEORIES AS TO THE ORGANISATION OF SIPHONOPHOR.E.

The morphological and physiological peculiarities which distinguish the Siphonophorse
from other Acalephse have led, as every zoologist is aware, to very diverse theories as to
the real nature and import of their organisation. Two essentially different interpretations
still stand in marked antithesis to one another, and these may for the sake of brevity be
described as the Poly-organ and Poly-person theories. Of these the poly-organ theory
is the older (Eschscholtz 1829, Huxley 1859, P. E. Midler 1871, Metschnikoff 1874).
According to this view the adult organism of all Siphonophorae is a simple " Medusa-like
animal," which is distinguished from the typical Medusae only in the multiplication
and differentiation of its polymorphic organs. More accurately defined, the organism
remains an individual Hydromedusoid person (a morphon of the third grade, or a
" morphological individual of the third order of individuality").

In contrast to this older interpretation is the poly-person theory (Vogt 1848, Leuckart
1851, Kolliker 1853, Gegenbaur 1854, Claus 1863, Chun 1882). According to this
view the adult Siphbnophoral organism is a colony of animals, composed of many polyp-
like individuals, which, according to the laws of the division of labour, have to undergo
various modifications, both in the way of specialisation and retrogression. More
accurately expressed, it is a " swimming Hydropolyp stock or conn," composed of many
polymorphic persons, partly polypoid, partly medusoid (a morphon of the fourth grade, or
a "morphological individual of the fourth order of individuality").

Since in the course of the last two decennia the ontogeny of Siphonophorae has become
better known, and since the latter has in the light of the theory of descent been inter-
preted in causal relation to likylogeny, the main antithesis between the two theories has
become more marked. According to the poly-organ theory the ontogenetic primitive
form of the Siphonophoraj is a simple Hydromedusoid person, and with this is in-
volved the phylogenetic corollary that the whole class originally arose from Medusae.
According to the poly-person theory, on the other hand, the ontogenetic primitive form
is a swimming Hydropolyp stock, and with this is associated the phylogenetic corollary
that the whole class sprang from Polyps.

(ZOOL. CHALL. ESP. — PART LXXVII. 1888.) IThllh 1

2 THE VOYAGE OF H.M.S. CHALLENGER.

According to the present opinion of most zoologists, which we also share, the low
sessile Hydropolyp form is the more primitive ; the higher Hydroniedusa form has
been secondarily developed at a much later stage, and that by adaptation to a free-
swimming mode of life. In this way has the characteristic swimming organ of the
Medusse arisen, namely, the umbrella, with its radially constructed gelatinous disc, which
was entirely absent in the primitive ancestral forms — the Polyps. The most important
structure of the latter, however, the gastral tube (inherited from the Gastrsea), has been
transmitted to the Medusae, and has become the " manubrium," in the wall of which the
generative products are devekrped.

If we apply this fundamental and firmly based conclusion to the two theories of
Siphonophore organisation, the following is evidently the antithesis in regard to the
question of origin. According to the poly-organ theory the primitive form of
Siphonophoras was a simple Medusa and already possessed an umbrella ; from this
established swimming organ the various locomotor organs of the Sipkonophora? ( swimming -
bells and air-chambers) are derived by multiplication and modification. According to
the poly-person theory, on the other hand, the primitive form of the Siphonophorse
was a Hydropolyp colony, and possessed no umbrella ; the locomotor organs which are
present are therefore new structures, not to • be derived from any pre-existing
swimming organ of the primitive form. And this leads to a weighty contrast in regard
to the Medusiform larva?, which arise directly from the gastrulse of Siphonophorse.
According to the poly-organ theory, such a larva possesses essentially the morphological
value of a simple Medusoid person, and as the hereditary repetition of the original
primitive form has the greatest palingenetic importance. According to the poly-person
theory, on the contrary, it possesses no such importance ; it is merely of subordinate
kenogenetic value, and is to be regarded as a peculiarly modified Hydroid polyp.

Both these opposing theories have been for forty years supported with much
acuteness by distinguished zoologists, but yet without decisive conclusion ; both are in
fact partially justified ; both contain a mixture of truth and error. According to my
own opinion, which is based on an extensive comparative investigation of the entire
class, and on numerous new facts discovered in the process, the truth lies midway
between the two interpretations. The poly-organ theory is right in starting in its
whole interpretation and rationale of the Siphonophorse from a Hydromedusoid type,
in regarding the primary medusiform larva as palingenetic, and further in supposing
an extensive multiplication and dislocation of the several Medusa organs. It is wrong,
however, in attributing to the fully developed Siphonophoral corni the value only of a
person, and in regarding the persons which compose the stock purely as organs in the
morphological sense. The poly-person theory, on the other hand, is right in explaining
the fully developed Siphonophore as a conn (colony or stock), composed of many poly-
morphic persons. It goes, however, much too far, and is in error when it seeks to

REPORT ON THE SIPHONOPHOR^E. 3

attribute to the several (morphological) organs of these persons the same individual
value {e.g., to the single protective bracts and capturing filaments); is furthermore
wrong in denying an extensive secondary multiplication and dislocation of these
organs ; and finally is especially at fault in regarding the primary medusoid larva as a
merely henogenetic embryonic form, and, by ignoring the palinge'netic value of the
latter, in interpreting the Siphonophorae as " swimming Hydropolyp colonies " comparable
to Hydractinia.

MEDUSOME THEORY.

The new theory of the. organisation of Siphonophoros to which I have been led by
my investigations on their comparative anatomy and ontogeny may be briefly designated
as the Medusome Theory. It seeks to incorporate the elements of truth in the two
views above described, but to avoid their errors. The principal positions of this
restatement may be briefly resumed: —

1. The primary larva, which arises directly from the gastrula of the Siphonophorae,
is always a simple Medusa ; it may be more or less kenogenetically modified, but
always retains a predominant palingenetic import, and is explained by the immediate
derivation of the Siphonophorae from Hydromedusae.

2. The primary medusiform larva of the Siphonophorse appears in two essentially
distinct forms, as a Disconula and a Siphomda, and since this distinction is associated
with essential differences in the resulting Siphonophoral colonies, the class may be
legitimately divided into two legions or subclasses, — Disconanthae and Siphonanthae.

3. The first legion, or Disconanthae, including the single order Chondrophoridae or
Porpitariae, develops from a regular and octoradial Medusoid larva {Disconula), retains
the original corona of marginal tentacles throughout life, and produces the persons of
the colony by annular budding from the subumbrella.

4. The second legion, or Siphonanthae, on the other hand, includes all the other
Siphonophorse (Calycophoridas, Physophoridaa, Pneumatophoridae, Aurophoridae) ; its
primary larva is a bilateral Medusa {Sii^honula), which is distinguished by a ventral
umbrellar cleft and by the possession of a single tentacle ; it forms the persons of the
colony by one-sided linear budding from the stomach-wall or manubrium.

5. The primary larva of the Disconanthse {Disconula) is to be regarded as the
ontogenetic recapitulation of a common primitive octoradial ancestor (Archimeda), and
its phylogenetic origin is probably to be sought among the Trachomedusae (Trachy-
nemidae, Pectyllidee).

6. The primary larva of the Siphonanthas {Siphomda) is to be regarded as the
ontogenetic recapitulation of a common primitive bilateral ancestor {Protomecla), and
its origin is probably to be sought among the Anthomedusre (Codonidae, Euphysidae).

4 THE VOYAGE OF H.M.S. CHALLENGER.

7. All the parts which arise by budding from the primary larva of the
Siphonophorae are either medusiform persons or special organs of the same.

8. All organs which belong originally to one medusoid person are included in the
definition of a Medusome, whether they bud out from a common basis on the stem, or
arise in different positions, in consequence of kenogenetic migration or dislocation ; the
multiplication of individual equivalent portions {e.g., nectophores, bracts, palpons) which
often occurs secondarily is simply to be regarded as a multiplication of organs, not of
persons or medusomes.

9. The medusomes appear on the Siphonophoral colony in two distinct main forms,
which cannot however be sharply distinguished — in the palingenctic medusomes the
principal organs have remained more or less in their original connection {e.g., in the
gonophores of Eudoxia); in the kenogenetic medusomes, on the other hand, the
principal organs are more or less dislocated, e.g., in the sterile medusome of Eudoxia,
which consists of a protective piece (umbrella) and a gastral tube (siphon) with a tentacle.

10. The lateral budding of the secondary medusomes (appendages) on the Siphono-
phoral stem occurs sometimes singly and sometimes in groups. Those groups which
consist of several medusomes we call " cormidia."

11. The cormidia are originally simple segmental repetitions of a medusome-group
in metameric succession separated by free internodes {cormidia ordinata), e.g., the
Eudoxise of the Calycophoridaa, the Prodoxiee of the Physophoridae {Apolemia, &c).

12. By the breaking up of such original cormidia, those centralised corms arise
in which the persons bud in a scattered fashion over the stem, their several organs thus
becoming separate from one another {cormidia dissoluta), e.g., Agalmopsis, Mhizophysa.

13. The degeneration of the single medusomes and of the disassociated organs is of
the greatest importance in the development of the Siphonophoral colonies, and that the
more, the more markedly the corm is centralised and the more intimate the mutual
relations between the polymorphic medusomes.

DISCONULA LARVA of the DISCONANTILE.

Among the different medusiform larvae of Disconanthae (Chondrophoridae or
Porpitarise) which I was able to observe, the youngest larvae of Porpitidae (from O'l to
0'4 mm. in diameter) are of special importance. They possess a circular, flatly arched
disc, the margin of which bears a circle of eight simple tentacles. From the middle
point of the subumbrella hangs a large central gastral tube, and from the base of this
siphon arise at equal distances eight radial canals, which run in the concave subumbrella
to the margin of the disc, and are there united in a circular canal. Above this there
lies in the middle of the gelatinous disc a pneumatophore, composed of a central lens-
shaped air-flask and a circle of eight radial air-chambers surrounding the same. Both

REPORT ON THE SIPHONOPHOR^. 5

the former and each of the latter possess on the middle of their upper surface an
external aperture (the stigma of the exumbrella). Only in the possession of this
hydrostatic apparatus is this Disconula distinguished from an ordinary eight-rayed
entirely regular Hydromedusa. Certain Trachoinedusae (Trachynemidse, Pectyllidse)
present a most striking resemblance. Even in another further advanced larval stage,
which we may call a Porpula, the regular structure of a simple Craspedote person is
still retained. The Porpula is distinguished from the Disconula in this, that the
number of marginal tentacles has increased from eight to sixteen, and several concentric
annular air-chambers are apposed to the primary circle of eight. In a stdl later stage
the number of concentric air-chambers' is greatly increased, and the tentacles form
several rows at the margin of the umbrella. Then between the margin of the umbrella
and the central siphon, eight or sixteen conical buds grow out from the subumbrella — the
subsequent bearers of the gonophores. They remain closed in the monogastric Discalidse,
but acquire a mouth opening in the polygastric Porpitidse and Velellidse. The youngest
larvaB of the Velellidse are hardly to be distinguished from those of the Porpitidse ;
the difference between them only becomes distinct when in the former the
vertical skin-fold of the exumbrella begins to be developed (Bataria), in the base of
which is formed the diagonal crest of the pneumatophore which determines the
amphithect ground-form of the Velellidse. Their youngest larvae, however, are as
octoradial as those of the regular Porpitida3. At an early stage they are distinguished
by this, that in the Porpitidse each of the eight radial air-chambers forms a stigma, in
the Velellidse only two lying obliquely opposed. The resemblance between these
larvae and the Pectyllidse suggests that the Disconanths have been originally developed
from this group of Craspedotse. If the eight sac-shaped gonads, hanging down from
the subumbrella of the Pectyllidse, were not themselves reproductive organs, but
medusoid gonophores, and if above these in the gelatinous substance of the disc, a
glandular depression or exumbrellar invagination led to the constriction of an air-sac,
then from a Pectyllid or Trachynemid there would be derived a very simple Discalid.

SIPHONULA LARVA of the SIPHONANTILE.

Entirely different from the first stage in the development of the Disconanthse, is
that of the second legion — the Siphonanthse (Calycophoridae, Physophoridse, Pneumato-
phoridse, Aurophoridse). Different as are the Siphonophorse of this manifold legion in
their fully developed form, their primary larval forms are very similar, at least so far as
their ontogenetic history is yet known. The Siphonula — or the primary medusiform
larva — is in this legion from the fii*st not octoradial and regular, but bilaterally sym-
metrical. The original circle of tentacles on the umbrellar margin has disappeared ; in
all cases only a single capturing filament (Fangfaden) persists, the primary unilateral

6 THE VOYAGE OF H.M.S. CHALLENGER.

larval tentacle, which in consequence of the ventral umbrellar cleft has been shifted
centripetally to the base of the gastral tube. The primary umbrella itself (Protocodon)
has in consequence of this unilateral development become bilateral ; it develops in the
Calyconect?e (or Calycophoridse) into tbe primary swimming-bell, in the other three
orders (Physonectse, Cystonecta;, and Auronecta?) into the pneumatophore. The
" swimming-bladder " arises here again as a gland-like invagination of the ectoderm, not
however centrally in the apex of the exumbrella (as in the Porpitaria?), but in an excentric
position. The primary siphon (Protosiphon) persists in the monogastric Siphonanths
as a single stomachic tube ; while in the polygastric forms it develops into the stem from
which all the other persons of the colony proceed by lateral budding. The whole
structure of the Siphonanthas, as well as that of their Siphonula larvae, suggests the
closest relationship with the Anthoniedusse, and especially with the family of Codonidge.
Only in these Anthomedusse do the reproductive elements develop in the entire gastral
wall (as in the manubrium of the gonophores in all the Siphonanths), without hint of
radial divisions. Among the Codonidaj, however, the subfamily Euphysidse (particularly
Hyhocodon and Amphicodon) is of especial importance. Here only do three of the four
primary tentacles of the umbrellar margin disappear, and one alone remains to attain a
proportionately greater development. In this way the bilateral modification of the
umbrella is determined. This origin of the Siphonanths is also corroborated by the
marked tendency of many Anthomedusse to form Medusae by direct budding from the
gastral tube (Codonivm gemmiferum, Sarsia siphonophora, &c). Since these Euphysidse
develop from Tubularian polyps of the genus Corymorpha, the latter are probably to be
regarded as the older ancestral forms of the Siphonanthas.

CORM and COPMIDIA.

All Siphonophorae are pre-eminently characterised by the development of a stock
(corm or colony), that is to say, of an individual organism which is composed of several
polymorphic persons (zooids or "individuals proper"). The laws and modifications of
this compositeness or colony-formation have been as yet but slightly investigated,
though they are undoubtedly very interesting and important. I distinguish in the
first place simple and multiple colonies. The simple colony (Cormus simplex) consists of
a single centralised group of persons, as in all Disconanthse and in the monogastric Siphon-
anthas. The compound or multiple stock, on the other hand (Cormus compositus), is
formed from the union of several individualised groups of persons, or " groiqis of
individuals scattered upon the stem," — the Cormidia. Such colonies are represented by
the polygastric Siphonanths. Each cormidium usually represents, in its general composi-
tion of several polymorphic persons, a simple stock, and is in most cases monogastric.
There are, however, polygastric cormidia, e.g., Apolemia, Salacia, Physalia. In all

REPORT ON THE SIPHONOPHORSE. 7

polygastric Siphonanthaa the cormidia are lateral, originally metameric branches of a
segmented trunk or jointed stem. This appears, however, in very varied form, as the
cormidia occur in distinct order or irregularly scattered and dissolved.

ORDINATE CORMIDIA.

In most polygastric Siphonanths (and therefore in the great majority of now existing
genera of Siphonophorse) the cormidia are ordinate, that is, regularly arranged as the
metameres of the jointed stem or corm axis ; the internodes, or regular intervals of the
stem between each two cormidia, are often quite free, especially in much elongated corms,
as for instance in almost all polygastric Calyconectse, in a number of the Physonectse
(Apoleniidse, many Agalmidse) and of the Cystonectas (Salacidse, many Rhizophyskke).
Not unfrequently in these stocks the elongated stem is so strikingly jointed by the
annular strictures separating the internodes at equal intervals, that the uniform and all-
pervading metameric structure of the Articulata is quite equalled. This comparison is
the more permissible, since the apical portion of the stem (representing the head) is
distinguished by the higher morphological differentiation of its group of persons. The
poly-organ theory might conceive these regularly jointed forms as Siphonophorse
articulata? in contrast to the others or Siphonophorse inarticulatse. But even when the
stem is much shortened and the cormidia so closely compressed that the internodes are
hardly distinguishable, the cormidia are often arranged with great regularity in a com-
pressed spiral row, as in the Discolabkke and Rhodalidse. In others, and often in nearly
related forms, the regular arrangement disappears, and gradually passes into the scattered
disposition of Cormidia dissoluta.

DISSOLVED CORMIDIA.

While in the majority of polygastric Siphonanths the corms are distinctly articulate,
and the cormidia are arranged in regular succession, this original arrangement is more
or less lost in one portion of this group, and in some entirely. The dissolution usually
begins in this way, that the siphons and gonophores belonging to one cormidium
separate ; the latter bud off directly from the stem, often regularly alternating with
the first, as in Polyphyes among the Calyconectaa, in Linophysa, Nectophysa,
Rhizophysa, among the Cystonectae, and in many Agalmidse among the Physonectae. In
consequence of further dissolution of the stem arrangement, the palpons and the bracts
also lose connection with the cormidia, and bud out directly from the stem, as in several
Agalmidse and Forskalidae. Finally the ordinate arrangement is quite lost, and the
entire stem exhibits hundreds or thousands of different appendages (siphons, palpons,
gonophores, bracts, &c.) in irregular grouping, so that it is impossible to distinguish

8 THE VOYAGE OF H.M.S. CHALLENGER.

the various connected components of the broken up cormidia (Physcdia, Agahnopsis,
and other Agalmidaj). This appearance is of the greatest interest, because, within one
and the same family (e.g., Agalrnidse, Rhizophysidse), most nearly related genera exist,
of which one possesses perfectly ordinate cormidia, another completely scattered, and a
third an exact transition between these two. In this fact lies the direct morphological
evidence of the multiplication and dislocation of the portions of the Siphonophoral stock.

DISLOCATION and MULTIPLICATION of ORGANS.

If our medusome theory is correct, the title of real persons (or " individuals proper")
is only to be applied to those portions of the Siphonophoral stock which have originally
the morphological value of a medusome-person, and not to those portions which were
originally only organs of such a person. If this be so, it is necessary to assume in many
cases a far-reaching dislocation and multiplication of the parts which were originally
organs of a medusome. This assumption is directly supported by the fact that the
replacement of primary organs by equivalent secondary structures does to a very large
extent take place. As such vicarious organs (reserve or replacement organs, " Ersatz-
organe"), I interpret, for instance, the numerous swimming-bells and covering bracts
of many Physonectse, the successive heteromorphic swimming-bells of the Calyconectse,
the groups of palpons in many Physonectse. On the other hand, in such an instance
as the clustered groups of reproductive members, each separate " gonophore " is to be
interpreted as a medusoid person which has lost mouth-opening and tentacles. The
morphology and " sociology " of the Siphonophorse must take much more account than
heretofore of these important tectological distinctions, and the rank of individuality must
be more strictly defined.

MONOGASTRIC and POLYGASTRIC CORMIDIA.

The ordinate cormidia contain usually only a single siphon, more rarely two or more.
The most important forms of monogastric cormidia (with a single siphon) are the
following : —

1. The Eudoxome of the Calyconectte (often becoming free as a " Eudoxia"), in
which each cormidium consists of two persons, one sterile (siphon with tentacle and
covering bract) and one fertile — the gonophore (often with accessory gonophores).

2. The Ersseome of the Calyconectae (often becoming free as an " Ersxa "), in which
each cormidium consists of three persons, having a medusoid " special swimming-bell "
added to the two persons above mentioned in the eudoxome.

3. The Rhodalome of some Rhodalida?, of Hippopodws, Vogtia, Aurophysa, Canno-

REPORT ON THE SIPHONOPHOR^E. 9

physa, Arethusa, &c, in which each cormidium consists of a siphon with a tentacle and
of one or more gonophores.

4. The Athorome of Physophora and of the Anthophysidee, in which each cormidium
consists of a siphon with a tentacle, one or more palpons, and one or more gonophores.

5. The Crystallome of Crystallodes, Anthemodes and other ordinate Physonectse, in
which each cormidium consists of a siphon with a tentacle, one or more palpons, one
or more gonophores, and a group of bracts.

Much rarer and much less manifold are the ordinate polygastric corrnidia, in which
each group of persons contains several siphons (each with a tentacle) ; such occur in
Apolemia among the Physonectse, and in Salacia among the Cystonectse. The line of
the stem, in which the cormidia originally bud forth in uniform succession, is the ventral
median line of the protosiphon ; usually it is rolled up in a wide or narrow spiral, rarely
it remains straight (Crystallodes, Stephanomia).

STEM or TRUNK.

(Ccenosome, Ccenosarc, Axial Body.)

The stem of the Siphonophorse, or the central axial body, on which all the various
persons and organs of the corm are attached, is generally compared to the stem of a
Hydropolyp stock. This comparison is in our opinion in the accurate sense illegitimate ;
for in the latter the primary larval body from which the corm develops is a Polyp-person,
while in the former it is a Medusa-person. The comparison holds so far, however,
inasmuch as the trunk is branched in both cases. It is not logical to describe the
stem of the Siphonophorse as " unb ranched " as is generally done. In reabty it is
always branched, for all the appendages — whether they be interpretable as persons or as
organs — arise as lateral branches of the axial body. Only the forking or dichotomous
ramification is here absent. Further, the conventional description which is generally
given of the stem or axial body of the Siphonophoras is strictly applicable only to one
legion of the class — to the Siphonanthse. For it is here only that the stem (whether it
be long or short) is formed from the primary siphon, and has all its appendages (or
branches) budded off in a row from its ventral median line. That they are subsequently
often radially disposed depends wholly upon a secondary spiral twisting of the stem,
and displacement of its appendages. It is quite different in the second legion, the Discon-
anthse. Here the proper stem, i.e., the common central portion of the corm, is formed
from the primary umbrella, and all its appendages (or branches) bud out from its lower
or subumbrellar surface, not in one row, but in concentric circles or rings, which are
originally octoradial. On the other hand the primary siphon in this legion has only the
value of a central nutritive organ.

(ZOOL. CHALL. EXP. — PART LXXV1I. 1888.) Hhhh 2

10 THE VOYAGE OF H.M.S. CHALLENGER.

NECTOSOME and SIPHOSOME.

In all Siphonophorse, without exception, both in the monogastric and polygastric
forms, the developed corm may be distinguished, both from a morphological and from a
physiological point of view, into two main portions, the nectosome and siphosome. The
nectosome or the swimming body forms in the Siphonophorse which swim quietly on the
surface of the sea, the upper, anterior or proximal portion of the stock ; the siphosome
or nutritive body the lower, posterior or distal portion. Physiologically the former is
the organ of locomotion (and often also of respiration), the latter, on the other band, the
organ of nutrition and reproduction. If one compares the Siphonophoral stock with the
simple medusoid person, then the nectosome in general represents the umbrella, and the
siphosome of the corm the manubrium of the Medusa. In the polygastric Siphonanths
the two portions pass through an independent course of development, separated from one
another, with distinct points of growth. In those Siphonanths where the stem is spirally
coiled, the spiral twisting is usually opposite in the two portions ; the nectosome has
usually a left-handed ("Lambda"), the siphosome a right-handed ("Delta"), spiral.

NECTOSOMES of the FIVE ORDERS.

The swimming apparatus of the Siphonophoree is formed of two essentially different
organs, the swimming-bell (nectophore) and the swimming-bladder (pneumatophore). The
nectophore is the umbrella of a Hydromedusa, in which both the annular muscular layer
of the velum and of the subumbrella, and the primary canal-system (four radial canals
united by a marginal circular canal) are perfectly developed. The pneumatophore, on the
other hand, is an invaginated and much modified umbrella, in the surface of which (by
apical or lateral invagination of a gas-gland) a chitinous gas-filled "air-flask" or pneu-
matocyst is formed. The definition of the five Siphonophoral orders is in the first place
determined by the different formation of the swimming apparatus.

I. The Calyconectye or Calycophoridse possess, only one, two, or more swimming-bells,
but no pneumatophore.

II. The Cystonectae or Pneumatophoridse bear only a simple large pneumatophore,
but no swimming-bells.

III. The Disconectse or Chondrophoridse possess an octoradial pneumatophore, usually
composed of concentric annular chambers, but no swimming-bells.

IV. The Physonectge or Physophoridse bear on the apex of the stem a simple
pneumatophore, and under that a biserial or multiserial column of swimming-bells ;
sometimes instead of these a corona of numerous bracts.

V. The Auronectae or Aurophoridse (a new and hitherto quite unknown group of
very remarkable deep-sea forms) possess on the apex of the stem a colossal pneumato-

REPORT ON THE SIPHONOPHOR.E. 11

phore, and underneath that a (simple or multiple) horizontal corona of swimming-bells,
and in the middle of the latter (in the dorsal median line of the nectosorne, opposite the
ventral row of buds) a large aurophore, a new, hitherto unknown organ, which is to be
regarded as a swimming-bell modified into a large gas-gland.

NECTOPHOEES or SWIMMING-BELLS.

(Nectocalyces, Nectozooids, Schwimmglocken , Schvnmmh ohlenstiicke. )

The swimming-bells generally exhibit so clearly the structure of the umbrella of a
simple hydromedusa person, that there can be no doubt as to their morphological
import as the locomotive organ of such a person — in the sense of the poly-organ theory.
The cavity of the gelatinous disc is clad throughout by the circular muscle layer of the
suburnbrella, and its distal margin protrudes in the form of a true velum, at the base of
which runs the circular canal which unites the four radials. The poly-person theory
interprets these facts, however, in this way, that each swimming-bell is to be regarded
as a medusoid person or "locomotive zooid," in which the locomotor umbrella is
well developed, but the nutritive manubrium degenerated. To this the medusome
theory has to reply that such a phylogenetic interpretation is not corroborated by the
known ontogenetic facts. The protocodon, or the "primary swimming-hell" of the
Siphonula is only an organ of this medusoid person. It does not remain as such in
most (if not all) of the Calyconectse, but becomes thrown off, and replaced by
metacodons or heteromorphic "secondary swimming-bells." In the monogastric
Calyconectse the protocodon is modified into the covering bract of the Eudoxia, whde
in the Physonectaj, Cystonectse, and Auronectse it becomes the pneumatophore. The
numerous metacodons, which in the Physonectse and Auronectse, as well as in the
Polyphyidae, form the two-tiered, many -tiered, or radially disposed swimming column,
are either displaced umbrellas of medusomes, which are repeated metamerically in the
several cormidia, or are simply vicariae or "reserve bells" ("Ersatzglocken") which
arise by the multiplication of such umbrellas, and are often present in great
numbers.

PNEUMATOPHORE or SWIMMING-BLADDER.

(Air-Chamber, Luftkam mer, Schwimmblase.)

The hydrostatic organ of the Siphonophorse, which is known as pneumatopliore, is
only absent in one order, that of the Calyconectse. In the other Siphonophorse it is
generally present and that in two different forms; the Physonectse, Cystonectse, and
Auronectse possess a simple swimming-bladder at the superior or apical pole of the stem;

12 THE VOYAGE OF H.M.S. CHALLENGER.

the Disconectae, on the other hand, have a complicated apparatus, composed of concentric
annular chambers, which occupy the greater portion of the umbrella. In all cases
the pneumatophore arises very early in the primary medusoid larva, and that by a gland-
like invagination of the exoderm of the exumbrella. In the bilateral Siphonula of the
Siphonanths this invagination has an excentric position (being often shifted down near
to the umbrellar margin), but in the octoradial Disconula of the Disconanths it is
central, in the very apical pole. The marked and apparently considerable differences
of the developing pneumatophore, in relations both of time and space, between different
(often nearly related) Physonectae, I simply explain as secondary cenogenetic modifica-
tions. That portion of the medusoid larval body on which the first trace of it appears
always belongs originally to the exumbrella.

In the Siphonanthae the invaginated portion of the exumbrella, comparable to a
simple, pouch -like, glandular sac, is known as the air-sac (pneumatosaccus); it secretes in
its superior or apical half a chitinous membrane, the air-flask (pneumatocystis), while its
inferior or distal portion (the "air-funnel") discharges the function of a gas-gland
(pneumadenia). The glandular (usually yellowish or greenish) epithelium of this last
portion secretes the air, which passes by the basal opening of the air-flask (" funnel aper-
ture," " Trichterpforte," or pneumatopyle) into the latter. The Cystonectae or Pneumato-
phoridae possess at the apical pole of the pneumatocyst an external air-hole or stigma (the
primary opening of invagination), by which the air may be discharged at will. In many
Siphonanths the air-secreting glandular epithelium of the air-funnel (or infundibulum)
grows through the aperture into the basal half of the pneumatocyst and clothes the
latter as endocystal tapetum, or " secondary ectoderm" (Chun).

In most Siphonanthae the air-sac becomes subsecpiently united with the peripheral
(uninvaginated) portion of the primary umbrella — the pneumatocodon — by a number of
vertical radial septa, usually eight, more rarely four or sixteen, and occasionally a variable
number. The radial pockets between these septa open inferiorly into the central canal
of the stem and represent the radial canals of a simple medusoid umbrella. On this is
based the opinion that the entire air-chamber is to be regarded as an " invaginated
swimming-bell " (Metschnikoff 1874). In contrast to this the air-chamber is at present
regarded by most zoologists as an independent medusoid person (or "medusiform zooid"),
and is supposed to originate as a "bud" from the primary larva (Leuckart 1875, Claus
1878, Chun 1887). The antithesis between these two opinions culminates in the inter-
pretation of the air-sac, which according to the first theory is the exumbrella of a medusoid
disc, according to the second the subumbrella. The latter opinion is according to my
conviction entirely erroneous, the former is in a certain sense admissible. The compara-
tive ontogeny of the Sipkonophorae appears to me to show conclusively that the air-sac
is an apical gas-gland of the exoderm, which in the Disconula of the Disconanthae sinks
centrally into the gelatinous disc from the apex of the same inwards, and in the Siphonula

REPORT ON THE SIPHONOPHOR^E. 13

of the Siphonanthse lies excentrically beside the apex. It arises in the former, indeed,
at the place where some Medusae (e.g., Aglaura) form a suctorial organ of attachment.
Only subsequently does this apical air-gland become greatly extended, to occupy the
greater part of the original larval umbrella, so that one may in a certain sense speak
of an " invagination." At any rate, the " air-sac " is originally a portion of the ectodermic
epithelium of the exumbrclla, not of the subumbrella. The whole pneumatophore is not
a secondary medusoid person, but the modified disc of the primary medusoid larva.

The many-chambered pneumatophore of the Disconanthas is comparable in its first
beginning alone with the single-chambered pneumatophore of the Siphonanthse ; there
again it is at first nothing more than an apical gas-gland, which occupies only a small
area on the apex of the primary larval umbrella. This simple central chamber becomes
rapidly surrounded, however, with a girdle of eight radial chambers, and around these
again many concentric rings of chambers are apposed. Thus arises the characteristic
octoradial, concentrically chambered air-disc of the Porpitidse, of which the amphithect
pneumatocyst of the Velellidse represents only a secondary modification. Sometimes its
margin is split into eight or sixteen radial lappets. On the upper surface the disc opens
by numerous stigmata, of which the central one alone can be compared to the simple
apical stigma of the Pneurnatophoridae. From the lower surface proceed numerous
small air-tubules or tracheae, which enter into the so-called "liver" or glandular central
organ. I regard only the entodermic canal network of this voluminous "central organ"
as " liver " (and perhaps " kidney "), and the compact exodermic parenchyma as a
strongly developed gas-gland. The lower ends of the tracheae are not closed, as is
generally supposed, but open. They take off the secreted gas, and their terminal
apertures correspond to the " funnel aperture of the air-flask " in the Siphonanthse.
On the other hand, the stigmata of the upper surface (or of the exumbrella) in the
Disconanthae do not serve for the reception of atmospheric air from outside (as is
generally supposed), but solely for the exit of the secreted gases, and correspond to the
simple apical pore of the Cystonectse.

AUROPHORE or AIR-BELL.

The new deep-sea famUies Stephalidae and Rhodalidse are distinguished from all the
other Siphonophorae by the possession of a peculiar organ, belonging to the nectosome,
designated the aarophore. Since they are in other respects peculiarly organised, they
may be regarded as representing a special order, Auronectse. The aurophore is a
voluminous gas-gland, which has developed out of a medusiform swimming-bell. It
lies below the large pneumatophore, in the dorsal middle line of the stem, opposite the
ventral row of buds. The disc-cavity of the swimming-bell has been modified into a

14 THE VOYAGE OF H.M.S. CHALLENGER.

narrow muscular air-duct (auroductus), which opens internally at the base of the
pneumatophore, and externally to the outside. The radial canals of the metamorphic
nectophore are modified into a complex radial system of wide glandular chambers.

SIPHOSOME or NUTRITIVE BODY.

The nutritive body exhibits in the different groups of the class Siphonophorae much
more manifold and important differences of form and structure than the swimming
body. Undoubtedly the most important difference is this, that in the Monosiphonise (or
the monogastric Siphonophorae) the archisiphon or protosiphon (the primary gastral tube
of the medusoid larva) remains alone as the organ for the reception and digestion of food,
while in the Polysiphonise (or the polygastric Siphonophorae), "secondary suctorial tubes"
or metasiphons are developed by budding, each provided with a gastric cavity
and a mouth opening. In the Polysiphonise the primary mouth opening of the medusoid
larva only rarely persists, in all Disconanthse, and in two families among the Siphon-
anthae (Stephalidse and Physalidae). In most (perhaps all the rest) of the polygastric
Siphonanthse, the primary mouth opening of the protosiphon is probably closed, and
the latter persists only as the stem of the stock (truncus or ccenosome).

The polymorphic appendages, which bud out as lateral branches from the stem of
the siphosome, are partly medusoid (bracts, gonophores), partly polypoid (sip>hons,
palpons, cystous, gonostyles). The poly-organ theory regards the former as multiplied
umbrellas of one Medusa, or as secondary vicaria of such, the latter as repeated
manubria or vicaria of the same. The poly -person theory, on the other hand, regards
each single bract as a medusoid person, which has lost all its organs except the umbrella,
and each single siphon and palpon as an independent Hydropolyp. Our medusome
theory regards in the different cases these polymorphic appendages partly as dislocated
organs of medusomes, partly as multiplied reserve organs or vicaria of the same.

SIPHONS or SUCTORIAL TUBES.

{Polypites, Gastral Tubes, Stomach Sacs, Nutritive Polyps, Eating Polyps,

Hydranth s, Gastrozooids. )

The siphons, which have given the name Siphonophorae to the entire class, are the
most important and the most constant appendages of their organism. From a physiological
point of view they are rightly regarded as organs for the reception of food and digestion ;
from a morphological point of view they are sometimes regarded as homologous
with an entire Polyp, sometimes with the gastric tube or manubrium of a Medusa.

REPORT ON THE SIPHONOPHOR.^. 15

As in the latter, each siphon or " suctorial tube " possesses at the distal end of the sac-
shaped body a mouth opening, at the proximal end a stem opening, through which the
simple cavity communicates with the cavity of the umbrella or the stem. By one or two
(often even three) annular strictures the simple cavity of the siphon is divided into
two, three, or four chambers. When four portions can be distinctly distinguished,
the first (proximal) is a thin stalk (pedunculus siphonalis), usually bearing the base
of insertion of the tentacle ; the second is a thick-walled crop (" Vormagen," basigaster)
equipped with masses of urticating cells ; the third is the stomach proper (stomachns) ,
usually with "hepatic stripes," more rarely with glandular villi; the fourth is an ex-
tremely contractile proboscis. The stomach usually passes without sharp boundary into
the proboscis, but is generally definitely marked off from the basigaster, often by means
of a pyloric valve. The stalk of the crop region is often degenerate or not distinctly
defined. The single tentacle springs from this portion in the majority of Siphonanthse.
According as the adult Siphonophoral corm has only one or several siphons, we distinguish
Monosiphonise and Polysiphonise.

MONOSIPHONLE or MONOGASTRIC SIPHONOPHOR/E.

Of great importance for the right understanding of the Siphonophorse is the fact,
that in all forms the primary medusiform larva (Disconula or Siphonula) bears only a
single siphon, and that this remains in one portion of the class, namely in the
Monogastricae, while in the other division it is modified into the stem, and is physio-
logically replaced by numerous secondary siphons (lateral branches of the latter).
Hitherto the monogastric Siphonophorse have been represented solely by the Eudoxise
among the Calycophoridse ; but among the new deep-sea Siphonophorse of the Challenger
Expedition which I have described in this Report, there are interesting monogastric
forms from three other orders (Discahdse, Athoridae, Cystalidae). Since in both legions of
the class the Monosiphonise exhibit close resemblance to the known larval forms of the
Polysiphonise, they may be regarded as " sexually mature larvse." In more accordance,
however, with the phylogeny is the reverse interpretation, that those larvse of the
Polysiphonise repeat, according to the fundamental biogenetic law, the structure of
their Monosiphonial ancestors.

In regard to the position of the stomach on the subumbrella, the Monosiphonise
exhibit in both legions very important differences, which are explained by their diphyletic
origin. In the Discalida? or monogastric Disconanths, the primary siphon occupies
the central point of a regular octoradial umbrella ; in the monogastric Siphonanths,
on the other hand, it is more or less excentrically situated at the base of a bilateral
umbrella.

16 THE VOYAGE OF H.M.S. CHALLENGER.

POLYSIPHONLE or POLYGASTRIC SIPHONOPHORffi.

In the great majority of Siphonophorse the adult form possesses several suctorial tubes
or polypites as organs for the reception and digestion of food. These arise in the Dis-
conanthae by budding from the primary subumbrella, in the Siphonanthse on the other
hand by budding from the ventral middle line of the primary siphon, which is modified
into the stem. In the former these " metasiphons " surround the primary archisiphon as
a corona ; while in the latter they are disposed upon the protosiphon either on the one
side only or on all sides, in a spiral line. In the simplest and most primitive case, such as
occurs in the polygastric Calyconectee and in many Physonectse, the metasiphons develop
in regular metameric succession on the segmented stem, separated by wide internodes.
Each individual siphon is (in the Eudoxise and the corresponding simplest Prodoxise of
the Physonectse) associated with a covering bract ; both together form a medusome, the
umbrella being represented by the bract, the manubrium by the siphon. In most of
the Physonectas numerous covering bracts soon develop, which are to be considered as
mere multiplications of the primary bract, and therefore as entirely subordinate organs.
But when from the base of such a medusome gonophores bud forth — appendages that is
to say of the morphological value of a medusoid person — then such a " group of persons "
acquires the value of a cormidium. In many Polysiphoniae the metameric arrangement
of the cormidia subsequently breaks up, and then the connection between the scattered
eiphons and the separated sexual medusomes is often no longer demonstrable.

PALPONS or TASTERS.

(Feelers, Tasters, Arms, Fluid Receptacles, Hydrocysts, Dactylozooids.)

In the great majority of the Siphonophoraa, the siphosome bears, scattered between the
siphons, or connected in groups with the latter, the tasters or feelers. These are always
simple, thin-walled, very contractile sacs, in which the proximal portion communicates
with the cavity of the stem, while the distal end is closed. Morphologically the tasters
are to be regarded as mouthless manubria, or as the stomachic sacs of medusomes in
which the umbrellas have become modified into covering bracts or are entirely degenerate.
The palpons are distinguished from the cystous by the absence of a distal opening, from
the siphons not in this alone, but also in the absence of the glandular villi and hepatic
stripes in the stomach region. Their function appears to be mainly, if not exclusively,
sensory. Their sensitive point probably acts generally as a taste organ, and sometimes
also as an eye ; in a (new) Athorybia I observed a lens in this ocellus (a sickle-shaped
pigment spot on the upper surface of the sensory apex). In some Agalmidse the distal

REPORT ON THE SIPHONOPHORjE. 17

part appears to act as an otocyst, since it is constricted off by a strong sphincter from
the wide palpon cavity, and forms a spherical terminal bladder in which a crystalline
otolith is kept in rotatory movement by a ciliated epithelium. Palpons are found
generally distributed in the Physonectse and Physalidae ; they are absent in the
Auronectae, Calyconectas, and Disconectae. Not unfrequently palpons are confused with
tentacles, as for instance repeatedly by Claus, even in Physojihora.

CYSTONS or ANAL VESICLES.

Under this title I distinguish from the other polypoid organs of the Siphonophorae
certain vesicular sacs, which have hitherto been generally confused with the palpons.
They are indeed very like the latter, but are very essentially distinguished from them
by a terminal aperture. By means of this aperture, which the animals can open or
close at will, fluid and excretions are emptied from the canal-system, and water may also
be taken in. It is therefore to be regarded as an anus. The distal portion of the
cystons is frequently pigmented and furnished with special glandular cells, they also
sometimes contain definite crystalline excreta. These anal vesicles obviously stand in
closer morphological and physiological relations with the siphons than with the palpons ;
they are, however, distinguished from the former by the simple structure of the wall.
I find these excretory structures widely distributed among the Physonectaa, but they
appear to be altogether absent in the other orders.

TENTACLES or CAPTURING FILAMENTS.

(Senkfaden, Stinging Filaments, Tentacular Filaments, Nematozooids.)

Tentacles are present in all Siphonophorae, and are both as capturing organs and as
offensive and defensive weapons quite indispensable. Recent reports of their absence in
some species are certainly to be explained by the ease with which the delicate threads
are during capture detached from their base. The poly-person theory regards the
tentacles as independent polypoid persons. I agree, on the other hand, with the poly-
organ theory, which explains them as organs of the siphons. In my opinion the
tentacles of the two legions of the class are in their nature entirely different. In
the Disconanths (or Porpitariae) the primary circle of tentacles on the umbrellar margin
of the medusoid larva (Disconula = Archimeda) persists ; there are at least eight present ;
their number usually becomes much increased ; they have no individual relations to
the separate siphons which bud forth in large numbers froni the suburnbrella. It is

(ZOOL. CHALL. EXP. PART LXXVII. — 1888.) HhlA 3

18 THE VOYAGE OF H.M.S. CHALLENGER.

quite different in all the other Siphonophorse — the Siphonanthse. Even their primary
medusoid larva (Siphonula = Protomeda) always possesses only a single tentacle, and
this is excentrically attached to the base of the primary siphon. The phylogenetic
cause of this peculiar position is to be sought in the bilateral modification, which the
older four-rayed medusoid ancestors of this legion (Codonidte) have undergone through
the degeneration of three marginal tentacles (Euphysidse). Only a single tentacle
remained persistent, and was all the more strongly developed ; it shifted in consequence
of the ventral splitting of the umbrella to the inferior surface of the latter beside the
base of the siphon. A similar centripetal migration of tentacles occurs also in Medusae,
sometimes on the superior, sometimes on the inferior surface of the umbrella. The
fact that each individual siphon of the polygastric Siphonanths bears at its base only a
single tentacle is simply to be regarded as the (hereditary) result of a metameric repeti-
tion of the primary condition.

Only in a few Siphonophorse do the tentacles remain simple cylindrical filaments,
as in the Velellidee, in Apolemia, Stephalia, Linophysa, Salacia, and allied genera.
In the great majority a row of lateral branches (side-filaments, accessory tentacles,
secondary filaments, or Tentilla) is formed, as in the Cladonernidaa (Pteronema,
Gemmaria). The terminal equipment of the latter by manifold cnidonodes or " stinging
knobs" is often very characteristic of the several genera and species. The Porpitidse
are distinguished by the possession of three longitudinal rows of secondary branches.
Some supporters of the poly -person theory regard each of these accessory organs as an
autonomous person, and Claus even states that the mantle-like covering (involucrum)
which in many Physonectae surrounds each stinging knob, apparently corresponds
morphologically to the disc of the Medusa (1878). In my opinion all these appendages,
however complex their structure, are merely subordinate organs of the second order.

PALPACLES or TASTING FILAMENTS.

Under this designation I include only the long, extremely contractile, hollow, simple
filaments, which occur in the majority of Physonectae at the base of the j>alpons. They
have the same morphological and genetic relation to the latter as the tentacles to the
siphons. While the tentacles are especially of importance as capturing organs and as
weapons, the palpacles act as fine, far reaching, tasting organs auxiliary to the sensory
function of the palpons. Each palpon bears always only a single palpacle, and this
is always simple, never stalked. . While the supporters of the poly-person theory regard
each palpacle as an independent " individual," that is as a distinct person, I must on the
other hand agree with the poly-organ theory, which explains them simply as subordinate
organs of the palpons.

REPORT ON THE SIPHONOPHOR^. 19

BRACTS or COVERING PIECES.
(Hydrophyllia, Protecta, Deckblatter, Covering Scales, Phyllozooids).

The polymorphic organs which are usually spoken of as " covering pieces"
(Deckstiicke) are entirely absent in the three orders Disconectae, Cystonectae, and
Auronectaa ; in the former originally, in the two latter probably as the result of degenera-
tion. In the two remaining orders the bracts are essentially distinguished in this, that
in the Calyconectae they appear singly on each Medusome, in the Physonectae on the
other hand there are several. Only the primary larva of the latter (Siphonula) frequently
forms a single " primary covering piece " (Protobractea), which is then to be compared
with the single bract of the former (Eudoxia), and to the umbrella of the primary
ancestral form (Protorneda).

The physiological importance of the bracts consists exclusively in their protective
function ; they are shields or umbrellar organs, under the shelter of which the other
persons of the colony are protected. As regards their morphological import, the poly-
person theory regards them as degenerate medusoid persons, which have lost manubrium
and tentacles, while the gelatinous disc has been the more developed; the poly-organ
theory, on the other hand, regards them as multiplied umbrellas. According to our
medusome theory, a distinction must be drawn between primary and secondary bracts.
The protobracteae or primary covering pieces, which occur singly, on the larvae of
Physonectae and on the Eudoxiae of Calyconectae, are to be interpreted as the umbrella
of a primary medusoid person. The metabracteae or secondary covering pieces, however,
which usually cover the stem of the Physonectae in large numbers, may have various
phylogenetic origins. They may arise as —

(1) Displaced umbrellas of secondary medusomes ;

(2) Vicariae or multiplied reserve-bracts of the same ;

(3) Cleft portions of divided (e.g., quadripartite) umbrellas.

The direct transition of nectophores into bracts is to be observed among the
Physonectae in the Athoridae and Anthophysidae. In Athoria and Rhodophysa, I find
in the distal portion of each bract a small rudimentary nectosac or swimming cavity,
sometimes with four cnidonodes or stinging knobs, which may be regarded as the rudi-
ments of four reduced tentacles. The highest and most manifold development of bracts
is found in the Calyconectae, where the sterile medusome of each single cormidium bears
a large hydrophyllium of a peculiar form, often characteristic of the genus. The phyllo-
cyst, too, or the canal of the bract, here often exhibits several apophyses, which may be
regarded as rudimentary radial canals of the umbrella; e.g., Aglaisma, the free Eudoxia
of Calpe, possesses four radial canals in its bract, two paired lateral and two odd sagittal
(an ascending and a descending canal).

20 THE VOYAGE OF H.M.S. CHALLENGER.

GONOSTYLES or REPRODUCTIVE STALKS.

(Blast ostyles, Gonoblastidia, Gonodendra, Klinozooids.)

The gonophores or the medusiform "reproductive persons" of the Siphonophoras
sometimes develop directly on the stem, that is as buds on the gastral wall of the
primary siphon. Such is the case in many monogastric Siphonophorse, and in several
polygastric forms (e.g. , in Agalmidse) with broken-up cormidia. Much more frequently the
buds arise from the stomach-wall of secondary polypoid persons, for which we shall use
Allman's title of Gonostyles or Blastostyles. These sacs are usually mouthless, and are
described as " tasters," but are better designated sexual palpons. Sometimes (in the
Porpitidse and Velellidae) these gonopalpons possess a terminal mouth, and may then be
called sexual siphons. These sacs frequently branch in a very marked tree-like fashion,
so that the numerous gonophores attached to them form large clustered masses
(reproductive-trees, gonodendra). From a physiological point of view the gonostyles
are distinguished both from the palpons and from the siphons very essentially in this,
that their sole function is the production of gonophores. From a morphological point
of view they may be regarded as sterile Polypo-persons, which are related to their
gonophore buds, as the Hydropolyp stock to its medusoid buds (poly-person theory).
In this case the succession of generations (strophogenesis) would replace the original
alternation of generations (metagenesis). According to the poly-organ theory, on the
other hand, each gonostyle is only to be regarded as an organ, corresponding to a
Medusa-manubrium, from which sexual medusoid persons of the next generation arise by
budding.

GONOPHORES or REPRODUCTIVE PERSONS.

(Sexual- Medusoids, Gonozooids. )

Among all parts of the Siphonophoral organism, the gonophores are always those
members which most distinctly preserve the original character of the medusoid person.
The two principal organs, the umbrella and the manubrium, are always present. In the
wall of the latter the generative products arise. But only in the Disconectse (and
perhaps in a number of Cystonectse) does the oral aperture of the manubrium appear to
break through; in the others it remains closed. The reproductive cells arise in both
sexes of the Siphonanthse from the entire surface of the manubrium (as in the Codonida?),
and indeed from the exoderm. The umbrella of the gonophores has the velum and
the circular canal of the umbrellar margin usually well preserved, and the same is true

REPORT ON THE SIPHONOPHORAE. 21

of the four radial canals of the subumbrella. Only rarely do these portions become
more or less rudimentary, so that the medusoid form is lost and passes over into a
more or less degenerate " sporosac." The tentacles on the umbrellar margin of the
gonophores have usually disappeared ; sometimes, however (as in some Calyconectse), four
rudiments are recognisable, and at other times even a corona of tentacular rudiments
(Desmojrfiyes). The Disconanthas, in which free reproductive Medusae in the sexually
mature state are not yet sufficiently known, may perhaps bud off four or eight separate
gonads either from the manubrium, or from the subumbrella.

As to the distribution of the two kinds of gonophores on the corm, it must be
noticed that most of the Siphonophorae are monoecious. Some Calyconectse {Mitroj>hijes,
Galeolaria) and some Physonectae (A'polemia, Athoralia) are dioecious. Among the
monoecious corms both kinds of sexual persons occur, sometimes in separate cormidia
(diclinous), sometimes associated in each single cormidium (monoclinous). The gono-
dendra, or the clustered groups of gonophores, are usually distylic, all their branches
bearing Medusae of the same sex; male and female gonodendra arising separately. But
sometimes there are monostylic gonodendra, the basal part of the single branched
gonostyle bearing female, and the distal part male, gonophores (as in the Auronectae
and Cystonectas, Forsbdia, &c). On the other hand, hermaphrodite persons {i.e., gono-
phores which form both spermatozoa and ova) are not known in this class. The male
persons are known as androphores, the female as gynophores. Usually the androphores
are slender, more oblong, and bear a spindle-shaped or cylindrical spermarium ; the
gynophores are thicker, more rounded, and bear an ovate or ellipsoidal ovarium.

FUNDAMENTAL FORM (PROMORPH).

The promorphology of the Siphonophorae has led to .very different views respecting
the ideal geometrical fundamental form (or the " promorph "), which may be
recognised by abstraction from the concrete single forms of these Acalephs. One group
of authors regards the Siphonophorae as " Radiate animals," whilst another group
maintains that they are "Bilateral animals." These opposed views are both right in a
certain sense. On the one hand, a typical radial structure — generally a quadriradial
form, composed of four equal quadrants — is recognisable in all Siphonophorae (mainly in
the gonophores and nectophores), and this is in my opinion produced by inheritance from
the older ancestral Medusae. On the other hand, a distinct bilateral structure — or a
dipieural fundamental form, composed of two symmetrical halves or antimeres — is
recognisable in most Siphonophorae, viz., in all Siphonanthae, whilst it is wanting in the
Disconanthae. This bilateral type is partly inherited from the bilateral Medusae, which
we regard as the ancestors of the Siphonanthae (Protomeda), and the essential form of

22 THE VOYAGE OF II. M.S. CHALLENGER.

which is presei'ved in the bilateral larva, Siphonula ; but partly the bilateral type is
produced by adaptation, and mainly by accommodation to the conditions of development
of the single forms. In order to get a clear conception of these difficult promorphological
relations, we must distinguish, firstly, the fundamental forms of the entire cormus and of
the single persons or medusomes composing it ; and secondly, the different promorpho-
logical development in the two independent legions of the class, the Disconantha^ and
the Sipbonanthse.

The promorph of the single medusome has the quadriradial medusoid type usually
clearly expressed, when the umbrella is well preserved, as in the gonophores and necto-
phores (always with four radial canals and a connecting marginal ring-canal). But also
in other parts of the medusomes the radial promorph may be recognised, as in those
siphons which possess four, eight, or sixteen hepatic stripes, mouth lobes, &c.

Promorph of the Corms in the Disconanthw. — The ideal geometrical fundamental
form exhibits in the colonies of Disconanthse two different types ; one of these,
represented by the Discalidae and Porpitidae, is the primary and original type; the other,
exhibited by the Velellidae, is a secondary modification. All corms of Discalidoe (Pis.
XLIX, L.) and of Porpitidse (Pis. XLV.-XLVIII.) preserve a completely regular
octoradial structure ; their ideal promorph is a regular octagonal pyramid. The vertical
main axis of this pyramid, around which the eight equal parameres are regularly
arranged, bears at its superior or apical pole the apical stigma of the central chamber of
the pneumatocyst, at its inferior or basal pole the mouth of the central siphon. The eight
equal sides of the pyramid are represented by the eight triangular radial chambers of the
pneumatocyst, whilst the eight perradial grooves between these, and the eight canals
running in the grooves, further the eight primary tentacles at the distal end of the canals,
mark the eight edges of the pyramid. The horizontal lines which connect these edges
with the vertical main axis are opposed in four pairs, and represent the four primary or
perradial cross-axes of the octagonal pyramid ; whilst the four secondary transverse axes
alternating with these, and bisecting the eight triangular radial girdle-chambers of the
pneumatocyst, are interradial. The perfectly regular octoradial promorph, which is so
clearly marked by the structure of the central pneumatocyst, is likewise expressed by the
entire structure of the canal-system, the eight primary perradial canals of the exumbrella,
the centradenia, the subumbrella, &c, by the regular octoradial corona of the eight
primary tentacles and gonostyles, the eight gastral ostia in the fundus of the central
siphon, the eight lappets of its mouth, &c. The young larva of all Discabdse and
Porpitidse (Disconula, PI. L. figs. 9, 10), and the simplest permanent genus of this legion
(Disccdia, PI. XLIX.), exhibit the octoradial type in the same complete regularity as any
octoradial Medusa (e.g., Trachynema, Pectyllis).

The Velellidae (Pis. XLIIL, XLIV.) differ from the regularly octoradial Porpitidaa
and Discalidae in the amphithoct modification of the promorph, which is usually called

REPORT ON THE SIPHONOPHOR^E. 23

" bilateral," sometimes even " uniradial " (Chun). But a comparative study of their
development, and mainly of the central part of their body, demonstrates that the corm
of all Velellidae originally is also octoradial ; this is clearly proved by the girdle of eight
radial lobes which surrounds the central chamber of the pneumatocyst ; further, by the
eight primary radial canals, which arise from the gastrobasis of the central siphon and
give off the ascending branches forming an octoradial liver-star on the upper surface
of the centradenia. Rataria (PI. XLIV.), as the simplest form of this family, and the
similar Ratarula-larvse of other Velellidae, possess marks of an octoradial type also in
other organs (eight primary buds of gonostyles, sixteen primary tentacles, &c). But
whilst the eight parameres in the Discalidae and Porpitidse are precisely equal (each
composed of two symmetrical antimeres), they are unequal in the Velellidae (each
composed of two asymmetrical antimeres). The two horizontal cross-axes, which are
perpendicular one to another, and to the vertical main axis, are both equal in the
Discalidae and Porpitidse ; whilst they are unequal in the Velellidae. Their sagittal axis
(marked by the vertical sail) is longer than the frontal axis (marked by the transverse
groove of the pneumatocyst). But the dorsal half of the corm (on one side of this
frontal groove) is symmetrically equal to the ventral half (on the opposite side), in the
same manner as the right half is symmetrically equal to the left (separated from it by
the vertical sail). The fundamental form of the corm in the Velellidae, therefore, is not
"bilaterally-symmetrical," but " amphithect," or bilaterally-octoradial, similar to that of
the Ctenophorae.

The octoradial structure of the Medusae is originally derived from the quadriradial
type, as I have demonstrated in my Monograph of the Medusae. The same promorpho-
logical law is valid also for the Disconectae. Their octoradial trunk has arisen from the
umbrella of some Medusa, the older ancestors of which were quadriradial. Their next
ancestral forms may be Trachynemidae, with eight radial canals, eight tentacles, &c.
But these again have arisen from the older Petasidae, which possess four radial canals,
four tentacles, &c. This older quadriradial structure is still preserved in the medusiform
gonophores of the Disconectae (Discomitra),

Promorph of the Corms in the Siphonanthse. — The corm of the Siphonanthae,
differing from that of the Disconanthae in all respects from the first beginning, is also
distinguished completely by its bilateral promorph. The primary larva (Siphonula),
which develops the corm of the Siphonanthae by unilateral budding from its manubrium,
has already a markedly bilateral fundamental form. Its primary umbrella has a deep
ventral cleft, and its only tentacle is attached to one side of the manubrium. The
vertical plane, which passes through the median line of these parts, is the sagittal plane,
and bisects the entire body ; the two halves separated by it, right and left, are
symmetrically equal. That side of the manubrium from which arise the buds of the
corm is the ventral side, the opposite the dorsal side.

24 THE VOYAGE OF H.M.S. CHALLENGED

In order to get a clear conception of the bilateral promorph of the Siphonanthaj
(very unnaturally described by many authors), it is very important to distinguish the
three primary dimensive axes, and to compare them with those of man or of some other
bilaterally symmetrical animal. The first or principal is the vertical main axis, the
longitudinal axis of the tubular stem ; its upper or apical pole bears the pneumatophore
in the majority of Siphonanthas, the primary nectophore in the Cabyconectse. The
opposite end is the lower or basal pole.

The second dimensive axis is the sagittal diameter ; its ventral or anterior pole is
marked by the series of buds, and usually by a ventral groove of the tubular stem. The
opposite dorsal pole is distinguished in the Auronectae by the aurophore, in Physalia by
the crest of the pneumatocyst. The vertical plane, which is determined by the sagittal
and the principal axes, perpendicular one to another, is the median or sagittal plane ; it
separates the right and left halves of the body.

The distinction between right and left halves (often confounded by different authors,
and described in striking contradiction) is always clear, when the ventral side is
constantly defined in the same sense as that side of the body from which the buds arise.
Therefore, the two poles of the frontal diameter, or the third dimensive axis (right
and left pole), must be always the same. In the monogastric Calyconectae, for instance
(Eudoxia, &c), the single siphon is placed on the ventral side of the bract (or the
modified umbrella) ; in the polygastric Calyconectae, correspondingly, the trunk is placed
on the ventral side of the first or proximal nectophore (the nectosarc, therefore, on its
dorsal side). In the Diphyidse, the ventral sides of the two nectophores are opposed one
to another.

The bilateral promorph of the Siphonanthse is at the same time quadriradial (or by
duplication of the parameres octoradial). This radial structure, inherited from the
ancestral quadriradial Medusas, is not only evident in the four radial canals of the
gonophores and nectophores, the eight hepatic stripes and mouth-lobes of many siphons,
&c, but also in the structure of the primary larval umbrella, and the pneumatophore
arising from it. The majority of the Siphonanthas exhibit in the basal part of the
pneumatosaccus eight (more rarely four or sixteen) radial pouches, which are separated
by vertical septa and comparable to the radial canals of a Medusa.

DESCRIPTION OF THE FAMILIES, GENERA, AND SPECIES.

SIPHONOPHOR^E.

Definition of the Class. — The Siphonophorse are swimming colonies or corms of
Hydromedusse, composed of polymorphous medusoid zooids or persons, which arise by
1 mdding from an original simple Medusa. The class is divided into two subclasses : — the
Disconanth^e arise by budding from tbe subumbrella, the Siphonanth^e by budding
from the manubrium of the original Medusa. The Disconanthce comprise one order only
(Disconectae) ; the Siphonanthse comprise four orders — Calyconeetse, Physonectse, Auro-
nectas, Cystonectae.

Synopsis of the Five Orders of Siphonophorse.

I. DISCONANTFLE : Truncus or coenosome formed by the umbrella of the original
octoradial Medusa, which includes a polythalamous pneumatocyst; the buds arise
in concentric girdles from the subumbrella. Larva octoradial (Disconula), . 1. Disconect.e.

II. SIPHONANTH.E.

Truncus or coenosome
formed by the manu-
brium of the original
bilateral Medusa ; the
buds arise in the ven-
tral line of the manu-
brium. Larva bilateral
(Siphonula).

No pneumatocyst or float filled by air. No palpons.
Always one or more nectophores are present,

2. Calyconect.e.

A monothalam-
ous pneumato-
cyst or a float
filled with air is
always present.

AVith nectophores
or with bracts
(often both to-
gether present).
With palpons.

Without aurophore ;
common stem thin,
tubular, with a
simple canal,

With an aurophore ;
common stem thick,
bulbous, with a net-
work of canals,

3. Physojstectj;.

4. AUEONECT.E.

Without nectophores, and without bracts.

Pneumatocyst with an apical stigma, . 5. Cystostect.e.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.)

Hhhh 4

26 THE VOYAGE OF H.M.S. CHALLENGER.

Subclass I. DISCONANTHAE.

Order I. DISCONECTvE, Haeckel, 1888.
(Pis. XLIII. to L.).

Clwndrophoras, Chamisso, 1821, 16,1 p. 363.
Velellids, Eschscholtz, 1829, 1, p. 165.
Cirrhigradx, Blainville, 1834, 24, p. 303.
Porpitariee, Haeckel, 18G9, MS. Canar.

Definition. — Siphonophorae with a permanent primary umbrella, without necto-
phores and bracts. Nectosome campanulate, lenticular or discoidal, including a poly-
thalamous, originally octoradial pneumatocyst, which exhibits numerous stigmata on its
upper face, and tracheae on its lower face. Siphosome composed of a central primary
siphon, and one or more concentric girdles of gonostyles (either secondary siphons, or
instead of these palpons), the latter producing gonophores. The primary larva
(Disconula) has a regular octoradial umbrella, with eight radial canals and a connecting
circular canal at the margin, which bears eight primary radial tentacles.

The order Disconectae comprises three families, the Discalidae, Porpitidae, and
Velellidae ; all members of this order agree in so many important characters, and differ
so widely from all the other Siphonophorae, that I divide the whole class into two
subclasses, Disconanthae and Siphonanthae. The first subclass, Disconanthae,
represented by the Disconectae only, is developed from the octoradial and octonemal
medusoid larva Disconula ; it retains the primary corona of eight or more marginal
tentacles, possesses a centradenia, and produces the polymorphous persons by budding
from the subumbrella. The second subclass, Siphonanthae, on the other hand, represented
by four orders (Calyconectae, Physonectae, Auronectae, and Cystonectae), differs in the
bilateral form of its mononemal larva, Siphonula ; this, as well as each of the following
siphons, has only a single tentacle ; the centradenia is wanting, and the polymorphous
persons of the cormus bud in the ventral line of the primary siphon.

History. — Eschscholtz, in his fundamental work,2 separated from the other Siphono-
phorae the family Velellidae, comprising the genera Porpita and Velella of Lamarck
(1815). So early as 1821 these were united as "Medusae chondrophorae " by Chamisso
and Eysenhardt. Eschscholtz added as a third genus Rataria, and found the peculiar
character of all Velellidae in the possession of an internal polythalamous cartilaginous
shell, the chambers of which are filled with air. Brandt afterwards (in 1835, 25)
separated the Porpitidae (with circular shell, without vertical crest) from the true Velellidae

1 The figures in black type refer to the Bibliography at the end of the Report.

2 System der Acalephen, 1829, p. 165, (1).

REPORT ON THE SIPHONOPHORjE. 27

(with elliptical or oblong shell, and a vertical crest). Huxley (in 1859) gave the first
accurate definition of this group (9, p. 71) : — " Physophoridse without nectocalyces or
hydrophyllia ; with short, clavate, simple or branched, submarginal tentacles. A single
central principal polypite. Pneumatocyst flattened, divided into chambers by numerous
concentric partitions, and occupying almost the whole of the discoidal coenosarc." The
description which Huxley gave of the two genera Velella and Porpita is very accurate,
as is also that given in 1853 by Kolliker (4). Another description of both has been
recently published by Alexander Agassiz (1883, 57). His opinion is that these Siphono-
phorse are more nearly allied to the Tubularise, and on the other side to the Hydro-
corallinse (Milleporidse, &c). The oldest figures are those of Forskal (11).

All authors hitherto agree in the general opinion that the Disconectse are the most
highly developed of all Siphonophorse, and that they form the terminal group in their
systematic arrangement, as being most closely allied to the Physalidse. In my opinion
this general view is quite erroneous. I am convinced, mainly by their ontogeny, that
the Disconectse have preserved the original medusoid structure more than any other
Siphonophorse (or the Siphonanthae). They retain the original umbrella with its corona
of marginal tentacles, and the original manubrium, which is the " principal polypite,"
or better, " central siphon." The gonostyles, or the polypiform persons which bear the
gonophores (either mouthless palpons or mouth-bearing siphons), bud from the sub-
umbrella (or the lower face of the disc) ; while the polymorphous persons in all the
other Siphonophorse bud from one side of the manubrium (or the primary siphon) in its
ventral line. The primary larva of all the Disconectse (Disconula) is a regular octoradial
Medusa, with a marginal corona of eight radial tentacles, widely different from the
larva of all other Siphonophorse (the Siphonula, with bilateral umbrella and a single
tentacle). I suppose, therefore, that there is no direct relation between the Disconanthse
and the Siphonanthse, and that the two subclasses or legions have a different origin :
the former arising from Anthomedusse (Codonidaa, Euphysidse), the latter from Tracho-
inedusse (Trachynemidaa, Pectyllidse).

Nectosome and Siphosome. — The two main parts of the fully-developed body, which
we separate as nectosome (or swimming apparatus) and siphosome (or nutritive apparatus),
have in the Disconectas a mutual relation very different from that of the other Siphono-
phorse (the Siphonanthag). The nectosome is represented by the exumbrella, or the
upper half of the discoidal body, which includes the polythalamous pneumatocyst ; the
sijjhosome, however, is formed by the subumbrella, or the lower half of the horizontal
disc, and by the different organs which are attached to its margin and to its lower face.
The boundary face between the two main parts is the upper face of the centradenia
or the so-called " fiver "; it is in close contact with the lower face of the pneumatosaccus.
The constant organs, which depend from the subumbrella, are the following : — (I.) The
large central siphon, in the middle of the lower face ; (II.) a simple or multiple corona

28 THE VOYAGE OF H.M.S. CHALLENGER.

of gonostyles, which bear the gonophores (mouthless palpons in the Discalidse, mouth-
bearing siphons in the Porpitidae and Velellidse) ; (III.) a simple or multiple corona of
submarginal tentacles.

Umbrella. — That part of the body, which is the true homologue of the umbrella in
the common Medusae, is in the Disconectse the most voluminous part of the whole cormus.
It includes the polythalamous pneumatocyst, and bears all the other organs on its lower
face. The latter corresponds to the subumbrella of the typical Medusae, while the upper
face is homologous with their exumbrella. Both faces are separated by the peripheral
margin or limb of the umbrella, which constantly bears a corona of muciparous glands.
The exodermal epithelium of the umbrella everywhere includes scattered nematocysts.
Beyond it there is a nervous plate, mainly developed on the limb and the upper face.
The muscles of the umbrella are more developed on the upper than on the lower face ;
they are composed of an outer layer of longitudinal or radial fibres, and an inner layer of
transverse or circular fibres.

Exumbrella. — The superior (apical or proximal) part of the umbrella, which is sepa-
rated from the inferior part (or subumbrella) by the glandiferous limb, is sometimes
a nearly even horizontal disc, at other times more or less convex. Its upper free face is
either smooth or papillate, always pierced by stigmata ; its lower face is in contact with
the centradenia. The exumbrella in all Disconectse is composed of two parallel plates,
which are separated by the reticulate plexus of the pallial canals ; the outer plate is the
pneumatocodon, the inner is the pneumatosaccus.

Pneumatophore, — The hydrostatic apparatus, or the swimming-bladder, which we
call pneumatophore, has in the Disconectse another and a far more complicated structure
than in all the other Siphonophorse (or the Siphonanthas). Only the first beginning can
be common to the two subclasses, viz., a simple pneumadenia, or a gas-producing gland of
the exumbrella. But this is centrally placed in the Disconanthse, excentrically in the
Siphonanthse ; and further, the chitinous pneumatocyst, which covers the inside of the
pneumadenia, is a simple monothalamous cyst in the latter, a multiple polythalamous
cyst in the former. Another important difference is furnished by the openings of the
pneumatocyst ; the simple pneumatocyst of the Siphonanthse is either closed, or has
only a simple opening (infundibulum) at the lower pole, and another simple mouth
(stigma) on the upper pole of its main axis. The polythalamous pneumatocyst of the
Disconanthse, however, has numerous openings on both faces, internal tracheae on the
lower face, external stigmata on the upper face.

Pneumatocodon. — The pneumatophore as a whole, or the hydrostatic apparatus, is
composed of all the above-mentioned parts, and of the two plates of the exumbrella also
already referred to. The outer or upper of these is the pneumatocodon, the uppermost
lamella of the entire umbrella. It is composed of three layers, an outer exodermal
epithelium, a nervous plate (composed of a loose reticulum of branched ganglion cells),

REPORT ON THE SIPHONOPHOR.ffi. 29

and a double muscle plate, with outer radial and inner circular fibres. The plexus of
pallia! canals separates the pneumatocodon from the pneumatosaccus.

Pneumatosaccus. — That lamella of the exoderm which surrounds immediately the
chitinous pneumatocyst, is the pneumatosaccus. It represents the invaginated part of
the exumbrella, and has taken its origin from a simple bottle-shaped gland in its apex.
This gas-secreting gland — or pneumadenia — originally small and occupying only the
apical centre of the exumbrella, has afterwards become so extraordinarily expanded that
it usually forms the most voluminous part of the entire umbrella. The exodermal
epithelium of the pneumatosaccus is a simple stratum of glandular cells, which secrete
the cuticular chitinous plate of the adjacent pneumatocyst. The basal part, or the
inferior face of the former, is probably also the matrix of the centradenia or the so-called
" liver." The exodermal cells, and cnidoblasts, which constitute the solid parenchyma of
the latter, are probably derived from the basal part of the pneumatosaccus.

Pneumatocystis. — The chitinous polythalamous float filled with air, which we call
pneumatocyst (formerly called " inner shell "), exhibits in all Disconectae a rather com-
plicated structure. Its general form is circular, and originally octoradial in the Discalidse
and Porpitidge, elliptical or nearly quadrangular (parallelogram) in the Velelliclse ; but
also in the young larva? of the latter its first rudiment is octoradial. It always commences
with the formation of a simple central chamber, which is situated in the centre of the
exumbrella, just above the gastral base of the large central siphon. It opens outside by
a central stigma in its upper face. Around this primary central chamber (the chitinous
lining of a central pneumadenia of the exumbrella) a peripheral corona of eight radial
chambers is next formed, each provided with an outer stigma on its upper side, and with
an articulate trachea on its lower side. These eight radial chambers are equal and
regularly radial in the Discalidse and Porpitidae, while they are more or less amphithect
and somewhat bilaterally disposed in the Velellidae. Sometimes in the latter family they
are more or less obliterated.

In the simplest case (Discalia, PL XLIX.) the formation of the pneumatocyst is
complete with the eight radial chambers ; in all the other Disconectae a different number
of peripheral concentric chambers is formed around their octoradial corona. All these
tertiary chambers are simple rings without radial partitions ; they open outside (in the
exumbrella) by a different number of stigmata, inside (in the centradenia) by a number
of open tracheae. The rings are circular in the Discalidae and Porpitidae, elliptical or
quadrangular (parallelogram) in the Velellidae. In these latter there usually arises after-
wards a solid vertical crest, placed diagonally on the upper side of the horizontal disc.

The general opinion regarding the physiological function of the polythalamous pneuma-
tocyst of the Disconectse may be summed up in the following propositions : — (1) The
Disconectse are exclusively pelagic animals, always floating on the top of the ocean, and
never sinking below its surface ; (2) the air contained in the pneumatocyst is atmo-

30 THE VOYAGE OF H.M.S. CHALLENGER.

spheric air, taken in by the stigmata of the exumbrella ; (3) this air is conducted through
the respiratory tracheae to the different appendices of the suburnbrella (central siphon
and gonostyles) ; (4) the distal or lower ends of the tracheae are closed.

The observations which I have myself been able to make on the structure and
function of the pneumatophore in the different groups of Disconectae have conducted
me to quite opposite views, viz., — (1) The Disconectae are (all or partly) capable of
sinking under water, by muscular compression of the pneumatocyst, and expulsion of
air by the stigmata of the exumbrella. (2) The air contained in the pneumatocyst is
not atmospheric air taken in by the stigmata, but a gas produced by the exodermal cells
of the great "central pneumadenia" (the so-called "liver" or central organ). (3) This
gas, therefore, has not respiratory, but hydrostatic functions (like the gas in the
swimming-bladder of the fishes). (4) The distal or lower ends of the tracheae are not
closed by a chitinous plate, but open into the glandular, gas-secreting, exodermal
tissue of the centradenia ; they are comparable to the " pylorus infundibuli " of the
Siphonanthae.

Central Siphon. — The large central polypite, which is placed in the centre of the
suburnbrella in all Disconectae, is the original manubrium of the primary medusiform
larva (Disconula) ; its terminal mouth is the permanent primary mouth of the latter.
The central siphon is the only organ of feeding and digesting in the monogastric family
Discalidae, whilst in the other two families of the order, the polygastric Porpitidae and
Velellidae, this function is also executed by the numerous peripheral gonostyles, which
are here developed in the form of mouth-bearing siphons or secondary polypites. But
also in the young monogastric larvae of these latter, the primary central siphon is alone
provided with a mouth. Its size is very variable in the different Disconectae ; generally
it is comparatively large in the small Discalidae, and in the smaller forms of Porpitidae
and Velellidae, which possess few secondary siphons ; on the other hand, it is relatively
small in the larger forms of the two latter families, which possess a great number of
feeding peripheral polypites.

The form of the central siphon in the Discalidae and Porpitidae is inversely conical,
with circular transverse section ; whereas in the Velellidae the inverted cone is stronelv
compressed from both sides, so as to be elliptical or lanceolate in transverse section. The
wider proximal or upper part, or the true stomach, passes without a sharp boundary into
the cylindrical, very contractile, distal or lower part, the proboscis. The latter, as well
as its distal opening, the mouth, is very variable in size and form, according to its state
of contraction.

The surface of the central siphon exhibits in many Disconectae a number of longi-
tudinal or radial folds, visible partly outside, partly inside ; usually there are eight or
sixteen, sometimes more. The distal mouth correspondingly often exhibits eight or
sixteen lobes, sometimes also four larger lobes ; at other times it is simply circular, or

REPORT ON THE SIPHONOPHOE^E. 31

in the Velellidae elliptical. In the expanded state the mouth may assume the most
different forms, trumpet-shaped, discoidal, &c.

The thick wall of the central siphon is always very contractile, and composed of
five layers: — (l) An outer epithelium or epidermis, rich in cnidocysts ; (2) a very
thick layer of strong longitudinal muscles ; (3) a solid fulcrum or a homogenous
structureless elastic supporting plate ; (4) a thin layer of circular muscles ; (5) an
inner epithelium or entoderm. The mouth is armed with peculiar cnidocysts and pro-
vided with sensillae. The upper or proximal half of the central siphon contains in its
epidermis often (but not always) a number of bent tracheae, which end here.

Gastrobasal Plate. — The basal or proximal part of the central siphon in all
Disconectae is separated from the superjacent centradenia by a strong fulcrum, or a
structureless elastic supporting plate (lamina gastrobasalis). This horizontal fulcral
plate (also called the roof of the central polypite, " le plancher " of Bedot, 59, 60) is
covered on the upper face by the basal surface of the centradenia, on the lower face
by the entodermal epithelium of the stomach. It corresponds to the jelly-plate which
forms the roof of the manubrium in the Medusae. Its central part is solid, whilst its
peripheral part is pierced by eight or more gastral ostia ; these form an octoradial corona
in the Discalidae and the smaller Porpitidae, whilst their number is increased in the
larger forms of the latter family (sixteen to thirty-two or more). Sometimes the
numerous ostia form here vertical lanceolate fissures, and the septa between them form
an elegant multiradiate star, composed of numerous vertical lamellae. The Velellidae
exhibit instead of this regular star a bilateral arrangement of the gastral ostia ; they
form here two opposite longitudinal rows of fissures (usually sixteen) on the two lateral
margins of the lanceolate gastrobasal plate.

Centradenia or Central Gland. — The central space of the body, between the apical
or proximal pneumatophore and the basal or distal central siphon, is in all Disconectae
occupied by a peculiar large glandular organ, wanting in all the other Siphonophorae (or
Siphonanthae). This interposed central organ is usually called the liver (hepar); but as
its structure and function are complicated and not merely hepatic, it may be better
called centradenia, or central gland. It is composed essentially of a dense network of
entodermal gastral canals, and of a compact parenchyma of exodermal epithelium, with
innumerable cnidoblasts, filling up the meshes or intervals of that network. The
physiological function of the gastral canals may be partly hepatic (digestive), partly
renal (excretory) ; the exodermal epithelium, however, seems partly to perform the
function of a pneumadenia (or gas-producing gland), partly to be a large reservoir of
cnidoblasts for other purposes.

The Form of the Centradenia is in general lenticular or discoidal, sometimes sub-
globular or even cylindrical, sometimes more conical or flatly expanded ; its peripheral
outline is circular, or sometimes regularly octagonal, in the Discalidae and Porpitidae ; it

32 THE VOYAGE OF H.M.S. CHALLENGER.

is elliptical or sometimes lanceolate in the Velcllidse ; often the periphery is more or less
lobate, corresponding to the form of the surrounding peripheral part of the umbrella.
The upper or proximal surface of the centradenia is attached to the lower or distal
surface of the pneumatosaccus, and separated from it by a thinner or thicker fulcrum, a
firm and elastic, structureless, supporting plate. But this supporting septum is wanting
in the young larva?, where the exodermal epithelium of the pneumatosac is in immediate
contact and connection with the upper face of the centradenia,

All the various and often complicated apophyses (radial ribs, circular rings, &c.)
which are formed by the distal or inferior face of the pneumatocyst, and its enveloping
jmeumatosac, are surrounded by corresponding furrows or envelopes of the proximal or
superior face of the centradenia ; the latter being always immediately attached to the
supporting plate, which separates it from the former in the adult Disconectse.

The lower or distal surface of the centradenia is in its central part in contact with
the base of the central siphon, in its peripheral part with that portion of the subumbrella
which bears the gonostyles. The fundus of the central siphon, or the uppermost part of
its cavity, is separated from the attached centradenia by a strong support, that sup-
porting plate, which has been described above as " lamina gastrobasalis." This elastic
and structureless plate is pierced in the periphery of the basal part of the stomach by
eight or sixteen (sometimes more) radial canals, which arise from the fundus of the
stomach itself and pass into the vascular system of the centradenia. We call these the
primary perradial gastro-canals. There are originally eight equal and regularly disposed
radial canals in the Discalidse and Porpitidse. In the Velellidse, on the other hand, they
are arranged in a bilateral manner ; two larger radial canals (a dorsal and a ventral)
arising from the opposite poles of the longer (sagittal) axis, two smaller (right and left)
from the poles of the shorter (transverse) axis, and four other (diagonal) canals in the
middle between the latter and the former. But usually the number of intercalated
secondary canals is here much larger, and their arrangement more or less irregular.

Origin of the Centradenia. — For the right understanding of this peculiar organ of
the Disconectse, a knowledge of its origin and development is essential. This question
may be solved by the comparison of very young Disconectas and mainly of the Discalidse,
These simplest and most primitive Disconectse remain permanently in a lower stage
of development, which is transitory in the Porpitidse and Velellicke. In the smallest
Disconula-larvse which I observed the centradenia is a small circular, biconvex, lenticular
disc ; its upper face is in direct contact with the pneumatosaccus, whilst its lower face is
separated from the central siphon by the gastrobasal plate (" plancher" of Bedot). The
entire mass of this solid disc is composed solely of exodermal cells and cnidoblasts ; it is
not traversed by any canals. The only canals of the centradenia are the eight simple
radial canals which run upon its upper face ; they arise from the eight ostia of the basi-
gaster, embrace the surface of the lenticular centradenia like eight meridian lines, and

REPORT ON THE SIPHONOPHOR^E. 33

unite in the centre of its upper face, forming a typical octoradial " liver star." This is
quite regular in the youngest Discalidse and Porpitidse ; it is amphithect in the young
Velellidse, where the two opposite canals of the sagittal axis are larger than the six
others, three right and three left (compare Bedot, 60, pi. ix. figs. 1, 2).

These eight primary liver-canals, running between upper face of the centradenia and
lower face of the pneumatosaccus, must be regarded originally as ascending branches of
the eight primary radial canals of the subumbrella, which run from the basigaster towards
the peripheral limb. All the numerous canals (partly hepatic, partly renal vessels) which
traverse the centradenia of the larger Disconectaj in all directions, and form a complicated
network, are merely secondary branches and ramifications of those eight superficial canals
of the primary "liver-star." They seem to be disposed and differentiated in a variable
manner. The majority of Disconectaa exhibit in the adult state a superior system of
hepatic vessels (characterised by production of brown or blackish pigment granules) and
an inferior system of renal vessels (characterised by the production of greenish guanin-
crystals), the so-called " white plate " of its discoverer, Kolliker.1

The cnidoblasts and the intermingled matter, indifferent or interstitial cells of the
exoderm, which, densely aggregated, constitute the solid glandular parenchyma of the
centradenia, doubtless have their origin in the exoderm. But the locality of their origin,
or the point of their exit between the central siphon and pneumatosaccus, has hitherto
been doubtful. Bedot, who has given the best and most accurate histological description
of the " central organ " of the Velellidse (58-61), assumes that the place of their origin
is the subumbrella. According to his description,2 a number of subumbral exoderm-cells
immigrate into the interior, passing through numerous pores of the subumbrellar support
(his " lamelle aniste externe," loc. cit.). These pores possess, in my opinion, a secondary
importance, and are perhaps artificial openings.

It seems to me much more probable that the exodermal cells of the centradenial
parenchyma may be derived from the basal or inferior part of the pneumatosaccus, i.e.,
that invaginated lamella of the exumbrellar exoderma which encloses and produces the
chitinous pneumatocyst ("couche cellulaire qui tapisse le pneumatophore " 3). This
important part of the pneumatosac is, in young Disconectse, in immediate contact with
the upper face of the centradenia, as Bedot himself has demonstrated.4 The structureless
support, which separates the two organs in the adult (" lamelle aniste interne " of Bedot,
loc. cit., p. 238), is not yet formed. This, in my opinion, is right, and the constituting
exodermal cells of the centradenial parenchyma are derived from the exumbrellar invagina-
tion of the pneumatosaccus ; they may be compared to the glandular gas-secreting cells
of the " infundibulum pneumatophori " of the Siphonanthse. I have very often found in
well-preserved specimens the cnidoblasts of the centradenia filled with an air-bubble, and

1 Kolliker, 4, p. 59. 2 Bedot, 59, p. 503, pi. xxv. figs. 4 le, 8 o.

3 Bedot, 59, pi. xxv. figs. 4, bin. * Bedot, 60, p. 238, pi. ix. fig. 2.

(zool. CHALL. EXP. — paet lxxvii. — 1888.) Hhhh 5

34 THE VOYAGE OF H.M.S. CHALLENGER.

this seems to confirm my opinion that the centradenia is not only a hepatic and a renal,
but at the same time a gas-secreting gland.

Canal System. — The system of gastral vessels or entodermal canals is in the Disco-
necta? very different from that of all the other Siphonophorse (or the Siphonantha?) ; it is
far more complicated and exhibits from the beginning quite a different type ; it is
originally octoradial, determined by eight primary perradial gastral canals, which arise
from the periphery of the base of the stomach and correspond to the eight subumbrellar
radial canals of a common octoradial Medusa (Trachynema, Pectyllis). This regular,
strictly octoradial type is retained through life in the central part of the canal system of
all Discalidse and Porpitidse, whilst in the amphithect Velellidae it is found only in early
stages, and afterwards becomes bilaterally modified, according to the different growth of
the two horizontal cruciate axes. No trace of this octoradial canal system is found in the
trunk of any other Siphonophora? ; but a similar type is apj^arently marked by the
octoradial structure of the pneumatosaccus in many Physonectse.

The peculiar development of the gastro-canals in the umbrella of the Disconectse is
produced, firstly, by the voluminous expansion of the pneumatophore and the invagination
of the exumbrella connected with it ; and secondly, by the development of the centra-
denia between the latter and the subumbrella. The following eight parts of the canal
system may be distinguished in the most highly developed Disconecta?, as we ascend from
the central siphon to the top of the pneumatophore : — (1) The system of subumbrellar
radial canals (originally eight), arising from the fundus of the stomach, and running
horizontally and centrifugally or ascending in the subumbrella towards the margin of
the umbrella ; they usually form a complicated network of dichotomously branched
radial canals. (2) The marginal canal, which connects the distal ends of the latter ; it is
placed in the true margin of the umbrella, and corresponds to the circular canal of the
Hydromedusse. (3) The system of renal canals or white excretory vessels, containing
green crystals of guanin ; it is formed by a network of branches of the subumbrellar
canals, which is placed usually in the basal or inferior part of the centrodenia. (4) The
system of hepatic canals or brown pigment vessels ; it is formed by the apical or superior
part of the canal network in the centradenia, in the surface of which it forms a
regular octoradial " liver-star." (5) The system of exumbrellar or pallial radial canals
(originally eight) ; these run centripetally and more or less horizontally in the exumbrella
towards the centre of the pneumatophore, where they are united by a small ring,
surrounding the apical stigma (" mantle-star ") ; they may be compared to the eight
radial pouches of the pneumatophore in many Siphonanthae. (G) The system of gono-
stylic cavities, or the gastral cavities of the polyps which bear the gonophores (palpons in
the Discalidse, siphons in the Porpitidse and Velellidae) ; they arise as simple subumbrellar
diverticula from the inferior branches of the centradenial system. (7) The canal system
of each single gonophore, composed of four radial canals and a connecting ring-canal,

REPORT ON THE SIPHONOPHOR^E. 35

identical with that of a simple Medusa ; the central union of the former is connected by a
pedicular canal with the gastral cavity of the gonostyle. (8) The system of the
tentacular canals or the simple peripheral vessels which arise from the periphery of the
subumbrellar system and pass into the tentacles.

Besides these eight parts of the canal system there occurs often (9) a coronal canal,
or a horizontal circular ring-canal placed in the coronal groove of the umbrella, between
the margin of the pneumatocyst and the centradenia. It represents an inner annular
vessel which carries on the circulation in the canals of the centradenia and the sub-
umbrella. The entoderm al epithelium exhibits a very different and remarkable shape in
these different systems of gastro-canals. The most important seems to be the rich
production of black or dark brown bdious granules in the hepatic vessels, and of green
guanin crystals in the renal vessels.

Eegarding the morphological value of these different parts of the gastro-canal system
of the Disconectae, and comparing them with the corresponding parts of a simple octo-
radial Medusa (Trachynemida), we may arrive at the following important conclusions : —

(1) The eight primary perradial canals, which arise from the base of the stomach (of the
central siphon) and run in the subumbrella towards the margin, are homologous with the
eight subumbrellar centrifugal radial canals of a simple Trachynemid (e.g., Pectanthis).

(2) The marginal ring-canal, which connects the former and runs along the limb of the
umbrella inside the series of marginal glands, is homologous with the usual marginal
canal of a simple Medusa. (3) The tentacular canals, which arise from the subumbrellar
canals and pass into the tentacles, are comparable to the tentacular canals of those
Medusae which possess submarginal tentacles (e.g., Drymonema). (4) The gonostylar
canals, which arise from the subumbrellar canals and pass into the cavity of the gonostyles,
are homologous with the cavities of the eight genital sacs of a Trachynemid. (5) The
eight centripetal radial canals, which arise from the coronal canal, run in the upper face
of the centradenia to its centre and there unite into a " liver star," may be compared to
the centripetal canals of the subumbrella of Carmarina, Pectyllis, and other Trachy-
medusae. (6) The coronal canal, or the inner ring-canal, which runs in the coronal
groove on the margin of the pneumatocyst, may be compared to the inner ring-canal
which develops by anastomoses of the radial canals in some Medusaa.

Whilst these parts of the canal system of the Disconectae may be compared to corre-
sponding parts of simple Trachyrnedusse, there are other parts which are quite peculiar to
the former. These secondary productions are : — (1) The pallial system or the anasto-
mosing radial canals of the exumbrella, which form a network on the upper face of the
pneumatophore. (2) The internal reticular canal system of the centradenia, forming a
hepatic plexus in its upper and a renal plexus in its lower half. The development of the
superficial pallial system of canals is a consequence of the invagination of the apical part
of the exoderm which produces the pneumatosaccus. The development of the internal

36 THE VOYAGE OF H.M.S. CHALLENGER.

centradenial system of canals, on the other hand, is the consequence of the centripetal
immigration of exodermal parenchyma between pneumatosac and gastrobasal plate,
producing the centradenia.

The innumerable ramifying and anastomosing branches of the above-mentioned vessels,
which form a very complicated network in the majority of Disconectee, are secondary
productions. Their mutual relations are best understood when we compare them with
the typical organisation of the simplest forms of that order, Discalia and Disconalia
(Pis. XLIX., L.). The canal system exhibits here three typical octoradial horizontal
stars : — (l) The pallial star above the pnoumatocyst ; (2) the hepatic star on the upper
face of the centradenia ; (3) the gastral star below the gastrobasal plate. The eight
peripheral main rays of these stars are united by the coronal ring vessel, which runs in
the coronal groove around the equator of the umbrella (PL XLIX. fig. 4).

Gonostyles. — The sexual persons of the cormus, or the zooids which produce the
medusiform gonophores of the Disconectse, are arranged in a girdle around the base of
the central siphon ; they occupy a smaller or broader zone of the subumbrella between it
and the corona of tentacles (gonostylar zone). These gonostyles or gonoblastidia are
mouthless palpons in the Discalidae, whilst they are either cystons or true siphons, pro-
vided with a terminal mouth, in the Porpitid?e and Velellicke. They are originally nothing
else than secondary manubria of a single Medusa person, budding from the radial canals
of the subumbrella. They may consequently be regarded as secondary persons, compar-
able to the buds of the Gastroblasta (described by Keller and Lang), and of other Hydro-
medusae budding from the subumbrella. On the other hand they may be compared also
to the genital sacs which depend from the radial canals of the subumbrella in the Trachy-
nemidae, Aglauridse, Pectyllidae, and in other families of Hydromedusse. If we imagine
that these genital sacs, instead of themselves producing ova and spermatozoa in their
exodermal wall, produce by budding Medusae which afterwards become sexually mature,
we shall understand how the Disconectse have originated from Trachomedusse.

The mouthless medusiferous pahpons of the Discaliclse, and the similar secondary
siphons of the Porpitidse and Velellidae (differing only in the possession of a mouth at
the distal end), have the same structure as the large primary central siphon, but are
always much smaller. Their number is originally eight, and they form a regular octo-
radial corona in some smaller and simpler genera {Discalia, PI. XLIX. figs. 1-4 ;
Porpalia, PI. XLVIII. ; Rataria, PI. XLI V.). Sometimes there are sixteen, e.g., in
Disconalia (PL L.) and Porpitella (PI. XLVL). But usually their number is much
increased, and amounts in the larger species to some hundreds. These cover the greatest
part of the subumbrella, the large gonostylar zone between the central siphon and the
corona of submarginal tentacles, often densely crowded without intervals. The form
and size of the gonostyles are very variable, owing to their great contractility. Some-
times they are more spindle-shaped, at other times more cylindrical or pyriform, with a

REPORT ON THE SIPHONOPHOR^E. 37

dilated basal part. Sometimes the proximal half, or the stomach, is separated by
a constriction from the distal half or the proboscis. The upper or proximal half only
produces by budding the numerous medusiferous gonophores, whilst the distal part, or
the contractile proboscis, is armed with cnidonodes. The wall is very contractile, since
the longitudinal muscles of the exoderm and the circular muscles of the entoderm are
not less developed than in the large central siphon. Sometimes the wall of the gono-
styles exhibits eight longitudinal folds or ribs ; and often, too, the patches of cnidocysts
(or the cnidonodes) are arranged into eight parallel longitudinal rows along the
proboscis.1

The gastral cavity of the gonostyles opens above into a canal of the subumbrella, or
of the centradenia. Its lower or distal end is a closed caecum in the monogastric
Discalidae, the terminal apex being densely beset with cnidocysts. It opens by a terminal
mouth in the Porpitidse and Velellidae ; this mouth is not less contractile and expansible
than the larger mouth of the central siphon. Often the former exhibits four cruciate
lips, more rarely eight ; sometimes it is circular, without mouth lobes (compare the
descriptions of the gonostyles by Kolliker (4), Vogt (5), Leuckart (8), Huxley (9),
Agassiz (57), and others).

Gonophores. — The medusiform gonophores arise from the proximal part of the gono-
styles, rarely isolated, usually crowded in smaller or larger groups or bunches. They are
in all Disconectae of the same form, and are detached from the budding gonostyle before
coming to sexual maturity. The detached gonophores are very small quadriradial
Medusae of very simple structure. Their subumbrella exhibits four regular radial canals
which unite above the velum by a circular canal (compare the above-mentioned authors).

Tentacles. — The limb of the umbrella is in all Disconectae armed with a corona of
tentacles, in the same manner as in all fully-developed Hydromedusae. They are placed
not at the margin itself, but more or less inside, at its lower face, the peripheral zone
of the subumbrella. They are, therefore, strictly speaking, submarginal tentacles (such
as occur also in some Medusae, e.g., Drymonema). Some authors (Glaus, Alexander
Agassiz, &c.) regard these organs as self-subsistent persons or zooids, and call them
" prehensile polypites," " marginal polypites," " tasters," " dactylozooids," &c. But this
conception is quite erroneous, and, in my opinion, there can be no doubt that the sub-
maro-inal corona of tentacles in the Disconectae are the same organs as in the common
Medusae, both from a morphological and from a physiological point of view.

Octoradial Corona of Tentacles. — It is a most important fact, not hitherto pointed out
as it deserves, that in the larvae of most Disconectae there occurs a typical stage, with a
corona of eight equidistant and regularly disposed tentacles. They are placed at the
distal end of the eight primary radial canals which arise from the base of the central
siphon, run along the subumbrella, and are connected round the margin by the circular

1 Compare 57, pi. ii. figs. 1-8.

38 THE VOYAGE OF H.M.S. CHALLENGER.

canal ; just as in the common octoradial Hydromedusse (e.g., Trachynema, Phopalonema).
This regular corona of eight simple radial tentacles is permanent in the simplest and oldest
form of the Disconectse (Discalia, PL XLIX. figs. 1-4). In all other genera of this
order the number of tentacles is rapidly increased, either by interpolation of eight inter-
radial secondary tentacles between the eight perradial primary ones, or by budding of
new secondary tentacles on both sides of the base of the primary ones, so that there
arise eight bunches of tentacles (Disconalia, PI. L. ; Porpalia, PI. XLVIIL). In the
larger Porpitidse their number is afterwards so multiplied, that the margin is armed with
a rich corona of many hundreds, or even thousands of tentacles (Porpema and Porpita,
Pis. XLVII. and XLV.). They are here densely crowded, and arranged in concentric
girdles (sometimes sis to nine or more) ; the uppermost (or proximal) girdle usually bears
the smallest, and the lowermost (or distal) the largest filaments. Their number is much
smaller in the Velellidee, where they form only a single submarginal series in Rataria
(PL XLIV.) and Velella, a double (or rarely multiple) series in Armenista (PL XLIIL).
Also in this family the original number seems to be eight, and in some smaller forms are
found sixteen ; but in consequence of the bilateral development of the umbrella, their
number and arrangement is often modified, bilateral, or irregular. In the young larval
forms (Ratarula) often two primray tentacles, situated at the opposite poles of the major
axis (or sagittal diameter) of the elliptic disc, appear earber than the others ; this
heterochronism is certainly kenogenetic.

Structure of the Tentacles. — The tentacles of the Disconectas are very different from
those of all other Siphonophoraa ; they are relatively short and thick, rather rigid, and
their movements are sluggish, as in most Trachoniedusae. In general they are far
less extensile and contractile, and do not exhibit that peculiar development and movement
which are obvious in most of the Siphonanthee, and are similar to that of the Anthornedusae.
The body of each tentacle in all Disconectse is a hollow cylinder with a very strong
muscular wall and a narrow canal, closed at the distal end and opening at the proximal
end into the annular canal of the margin, or the marginal zone of the canal network.
The wall is composed, as usual, of the following five strata, enumerating them from with-
out inwards: — (l) An exodermal epithelium, armed with cnidoblasts, often vibratile in
some parts ; (2) a strong layer of longitudinal muscles ; (3) a thin, but firm and elastic
structureless supporting lamella ; (4) a thin layer of ring-muscles ; (5) a vibratile
entodermal epithelium, lining the central canal, composed of very large vacuolate
entoderm cells similar to the axial cells in the tentacles of many Trachomedusse.

The armature of the tentacles with cnidoblasts exhibits characteristic differences in
the families of Disconectse. Discalia, (PL XLIX. figs. 1-4), as the simplest form of all,
and likewise probably the youngest larval stages of all Porpitidae, possess eight simple
tentacles, which bear a single cnidosphere (or a spherical knob composed of cnidocysts)
at their distal end (PL L. fig. 9).

REPORT ON THE SIPHONOPHORiE. 39

The next larval stage of the Porpitidse exhibits four stalked cnidospheres at the
distal end of each tentacle ; ! one of these is the primary terminal knob, whilst the three
others are lateral branches (PL L. fig. 10). By multiplication of the latter in the
prolonged tentacle arise three longitudinal rows of stalked cnidospheres, one of which
is situated on the inferior or distal side of the tentacle, the other two opposite on its
two lateral sides. These three longitudinal rows of short lateral branches, each of which
bears a spherical cnidonode, are very characteristic of all Porpitidse ; each row bears six
to nine or more branches in the larger species, their size decreasing from the terminal
(oldest) branch towards the basal (youngest). The basal half of the tentacles is usually
simple, and bears no branches.

The tentacles of the Velellidse are never branched ; they always remain simple
cylindrical filaments, and are relatively short and small. The cnidocysts are either
irregularly scattered on their surface, or form two opposite ribands on the two lateral sides.

Ontogeny. — The individual development of the Disconectse is very incompletely
known, but seems always connected with a peculiar form of metagenesis. The first
generation is asexual, the complicated cormus above described producing at its sub-
umbrella numerous polypites or secondary manubria (mouthless palpons in the
Discalidse, mouth-bearing siphons in the Porpitidse and Velellidse). From the gastral
wall of these secondary polypites (surrounding the sterile central siphon) there arise
numerous medusiform buds of the form Discomitra. These do not become mature
whilst sessile and attached to their parents, but are soon detached, and develop into free
Hydromedusae, which produce ova and spermatozoa. Some advanced stages of this second
sexual generation are described by Gegenbaur as Chrysomitra, and possess eight or
sixteen radial canals ; but they have not hitherto been sufficiently examined in the
adult state. The origin and structure of the sexual organs of the Disconectse, ovaria as
well as spermaria, require a further accurate examination.

It is very probable (though not observed) that from the fertilised egg of this second
generation arises a young Medusa with eight radial canals, and that this early produces
in the top of its hemispherical umbrella the pneuinatocyst, at first a simple central
chamber (comparable to the simple pneuinatocyst of the Siphonanthse) and subsequently
a corona of eight radial chambers. From this common larval stage probably arise two
different lines of individual development. The Discalidse, on one hand, remain regularly
octoradial, and develop eight marginal tentacles (with increasing number), and between
these and the central siphon eight or sixteen gonostyles, remaining mouthless palpons.
The Porpitidse retain the same regular octoradial type, but are further developed, and
their gonostyles, at first mouthless, acquire afterwards a distal mouth-opening and
metamorphose into secondary siphons.

On the other hand, a different course is followed by the bilateral Velellidse. Here

1 Compare A. Agassiz, 59, pi. ix. fig. 1.

40 THE VOYAGE OF H.M.S. CHALLENGER.

there arises early a vertical longitudinal fold of the exoderm above the pneumatocyst ;
and this commencement of the typical vertical sail determines the amphithect or
bilateral development of this family ; the umbrella becomes elliptical, and the gonostyles
bud between central siphon and corona of tentacles, not in concentric circles (as in the
Porpitidae) but in elliptical or oblongish rings. The ontogenetic metamorphosis of these
larvae, developing into the first asexual generation, is not completely known in any
Diseonectae. For further particulars regarding the ontogeny reference may be made to
the works of Kolliker (4), Vogt (5), Gegenbaur (7), Huxley (9), Pagenstecher (55), Alex-
ander Agassiz (57), and others.

Phytogeny. — The historical or phylogenetic development of the various forms of
Sipkonophorae, which we unite in the legion Diseonectae, may be partly recognised from
the critical study of their comparative anatomy and ontogeny. By this means I have
been conducted to new views of the origin of this interesting subclass, quite different
from those of all naturalists who have hitherto treated the question. The general
opinion is that the Diseonectae are the most highly developed Siphonophorse, terminating
the series of this class, and most nearly related to the Cystonectae (Physalidae). Even
the radial chambers of the pneumatophore of the Diseonectae have been often compared
to the crista-chambers of the pneumatophore of Physalia. This comparison, and all the
important consequences deduced from it, are, in my opinion, perfectly erroneous. In
direct contradiction to it, I am convinced of the truth of the new theory which I have
already shortly explained in my propositions ; ! its principal points are here repeated.

The Diseonectae (or Disconanthae) have no direct relation to the Siphonanthae (or all
other Siphonophorae) ; they have originated, independently of the latter, in a different
way and from a different group of Hydromedusae. Whilst the Siphonanthae are probably
the offspring of the Anthomedusae (Codonidae), and their cormus developed by budding
from the ventral line of the original siphon, the Disconanthae, on the other hand, are
probably descendants of the Trachomedusae (Trachynemidae), and developed by budding
from the subumbrella.

The common ancestral group of all Disconectae is the family Discalidae (most nearly
allied to the Trachynemidae). From these, probably, the two other families, Porpitidae
and Velellidae, have been developed as two divergent branches, or, perhaps, the latter
have been derived directly from simpler forms of the former family.

Synopsis of the Three Families of Diseonectae.

1. Umbrella circular and regular octoradial. Blastostyles without mouth, . . 1. Discalidae.

2. Umbrella circular, in the centre octoradial. Blastostyles with a mouth, . . 2. Porpitidae.

3. Umbrella elliptical or bilateral. Blastostyles with a mouth, . . .3. Velellidas.

1 System der Siphonophoren, Jena, 1888.

REPORT ON THE SIPHONOPHOR^E. 41

Family I. Discalidse, Haeckel, 1

Discalidx, Hkl., System der Siphonoplioren, p. 29.

Definition. — Disconectse with an octoraclial circular permanent umbrella, including
a circular, campanulate or cliscoidal pneumatocyst, without vertical crest. No vertical
sail upon the umbrella. Submarginal tentacles of the umbrella simple or branched, with
terminal cnidospheres. Central siphon surrounded by numerous mouthless palpons,
which bear the medusiform gonophores.

The family Discalidse comprises some new, small, but very interesting Siphonophoraj
from the deep sea, which were found in the collections of the Challenger. They are in
general very similar to young Porpitidae, but differ from them in the very important
character, that the large central siphon alone possesses a mouth, while the surrounding
gonostyles or blastostyles are mouthless palpons. The Discalidse are therefore " Disco-
nectie monogastrica}," and become mature in the monogastric state, which is a transi-
tional larval stage in the Porpitidse. These latter, as well as the Velellidse, are in the
adult state " Disconectse polygastricse" each gonostyle possessing a mouth and repre-
senting a peripheral sexual siphon. The Discalidse may be regarded as the simplest and
most primitive of all Siphonophorse, since they retain the original character of a simple
octoradial Medusa (like Trachynema or Pectyllis) more nearly than all the others.

Umbrella. — The complete body of all Discalidse is circular, sometimes more lenticular
or discoidal, at other times more campanulate or even subglobular. The vertical or main
axis is, therefore, sometimes nearly as great as the horizontal or equatorial axis, at other
times scarcely half as great, or even less. The free prominent margin, or the glanduli-
ferous limbus umbrellse, marks the boundary between its upper (apical or proximal) face,
the exumbrella, and its lower (basal or distal) face, the subumbrella. The former includes
the pneumatophore, and represents with it the nectosome ; the latter is the siphosonw,
and bears in its centre the large primary sterile siphon, around this numerous sexual
palpons (or gonostyles), and towards the margin the corona of tentacles.

A vertical meridional section through the umbrella (PI. XLIX. fig. 4) demonstrates
that the superior half of the umbrella is occupied by the pneumatocyst (ph), the inferior
by the large centradenia (uc), and from this depend in the centre the large central siphon
(sa), and around it the corona of gonostyles (gs). A deep circular coronal groove
separates this latter from the corona of submarginal tentacles.

Exumbrella. — The superior (apical or proximal) face of the umbrella is flat or slightly
convex, smooth, and pierced by the stigmata of the pneumatocyst. It is composed of
two parallel lamellse, which are separated by the network of the pallia! vessels. The
external or superior lamella is the pneumatocodon, which contains numerous cnido-

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hllhh 6

42 THE VOYAGE OF H.M.S. CHALLENGER.

cysts, and (usualty) exhibits a distinct octoradial pigment star in its centre (fig. 7). The
internal or inferior lamella is the pneumatosaccus, the invaginated plate of the exoderm,
which secretes the chitinous pneumatocyst. Its lower face is in contact with the upper
face of the ccntradenia.

Limbus Umbrella? (PI. L. figs. 1, 9, us). — The free horizontally prominent margin of
the umbrella, which separates the exumbrella from the subumbrella, is in all Discalidse more
or less octolobate ; the eight interradial convex lobes are the more prominent, the deeper
are the eight incisions in which are inserted the marginal tentacles. The whole edge of.
the mantle-border is beset with a continuous series of marginal muciparous glands.

Subumbrella. — The inferior (basal or distal) face of the umbrella is convex, and bears
in its centre the large conical central siphon, around this a corona of gonostyles (eight
in Disealia, sixteen in Disconalia), and in the peripheral part a simple or double corona
of tentacles (eight simple tentacles in Disealia, PI. XLIX., eight radial bunches of
numerous tentacles in Disconalia, PL L.).

Pneumatocyst (PI. XLIX. figs. 4, 5, 8, 9). — The float filled with gas, which is in-
cluded in the pneumatosaccus, always exhibits in the Discalidse a regular octoradial
structure. This is of typical simplicity in Disealia (PI. XLIX. figs. 2-5), composed only
of a subspherical central chamber and a surrounding regular ring of eight equal triangular
radial chambers. The more advanced genus, Disconalia (figs. 8, 9), exhibits the same
biconvex octoradial disc in its central part ; but it is here surrounded by a peripheral
girdle of five to ten concentric ring-chambers ; the middle ones of these are far broader
than the innermost and the outermost.

Pncumoihyrie. — Each of the eight radial chambers of the central disc of the pneuma-
tocyst communicates with the common central chamber by an inner opening or pneumo-
thyra, placed on the proximal apex of the triangular chamber. Opposite to this lies in
the centre of its distal base another pneumothyra, which opens into the first or innermost
ring-chamber. An interradial series of similar septal openings, by which every two
neighbouring chambers communicate, lies in the centrifugal continuation of the interradial
line, which bisects each triangular chamber and connects its apical with its basal pneumo-
thyra. They are, therefore, in Disconalia eight regular interradial rows of pneumothyrse
(PI. XLIX. figs. 8, 9, pg), and these alternate regularly with the eight perradial grooves
which separate the eight triangular chambers from one another, are continued to the peri-
pheral margin of the pneumatocyst, and divide the latter into eight ecpial triangular
octants. The free margin of the pneumatocyst thus becomes distinctly octolobate.

Stigmata (PL XLIX. figs. 2, 5, 8, 9). — The superior (apical or proximal) face of the
pneumatocyst bears the stigmata or the short tubular openings which pierce the cx-
urnbrella and permit an expulsion of the enclosed air. Disealia (fig. 2) has only nine stig-
mata, one central, in the central chamber, and one in each of the surrounding eight radial
chambers. In Disconalia (figs. 8, 9) this number is increased hj a variable number of

REPORT ON THE SIPHONOPHOR^E. 43

accessory stigmata, lying in one or in several of the concentric ring-chambers. Usually
the third or fourth only of these exhibit eight stigmata, placed in the interradial lines,
which pass through the former. But sometimes these accessory stigmata are irregularly
scattered. The gas enclosed in the pneumatocyst may issue by these stigmata, when the
strong muscle-plate of the surrounding pneumatosaccus contracts.

Trachese (figs. 5, 9,pt). — The inferior (basal or distal) face of the pneumatocyst bears
the aeriferous tubules which receive the gas secreted by the pneumadenia and conduct it
into the chambers of the former. The simplest genus, Disculia (fig. 5), possesses only
eight short trachea?, which arise from the peripheral part of the inferior side of the eight
triangular radial chambers. The more highly developed Disconalia (fig. 9) exhibits,
besides these latter, a greater number of peripheral trachese, arising from the lower face
of the concentric ring-chambers ; they are more numerous in the innermost than in the
middle ring-chambers, and are wanting in the outermost. Their number amounts to from
twenty to eighty or more ; their arrangement is variable and irregular. The trachese in
all Discalidse are very short and small, their cylindrical articulate tubules composed of
ten to thirty small conical segments. They are more or less irregularly curved, and
descend in various directions into the solid glandular parenchyma of the centradenia,
where their open distal ends are surrounded by exodermal cells. In no Discalidse do the
short trachese pierce the entire centradenia and the subjacent gastrobasal plate, nor do
they enter into the base of the wall of the central siphon and the gonostyles, as is the
case in the Porpitidse.

Central Siphon. — The large central polypite, which corresponds to the manubrium or
gastral tube of the original Medusa, in the Discalidse is relatively larger and more
developed than in the Porpitidse and Velellidse. It is in the former the only organ for
the reception of food and digestion, whilst these nutritive functions in the two latter
families are executed also by the sexual peripheral siphons. The central siphon of the
pyriform Discalia (PI. XLIX. figs. 1-4, sa) is very elongated, and about as long as the
greatest diameter of the umbrella, whilst it is much smaller in the discoidal Disconalia
(PI. L. fig. 1) ; its diameter (in length and breadth) is here only one-third or one-fourth
of the latter. The basal part (or stomach) is ovate or pyriform, the distal half (or
proboscis) cylindrical. The thick, very contractile wall is composed, as usual, of a
stronger exodermal longitudinal layer of muscles, and a thinner entodermal layer of
circular muscles, separated by an elastic structureless support.

The fundus of the stomach is separated from the superjacent centradenia by the
horizontal gastrobasal plate. The periphery of this sobd circular or octagonal support
exhibits eight equidistant openings, the ostia, which conduct into the eight radial canals
of the subumbrella. These ostia are prolonged sometimes downwards into eight longi-
tudinal grooves at the inside of the stomach, and to these correspond eight longitudinal
folds or ribs on its outside.

44 THE VOYAGE OF H.M.S. CHALLENGER.

The mouth or the distal opening of the central siphon is either circular or octagonal,
with eight short regular lips or radial mouth lobes (PI. L. figs. 1, 3). Its edge is
strongly armed with cnidocysts.

Centradenia (PI. XLIX. figs. 4; 10, 11). — The large central gland, which is called
the " liver " in the Porpitidse and Velellidse, does not exhibit in the Discalidse the coin-
plicated structure seen in those two families, but merely a typical and most instructive
simple shape. It is a biconvex lenticular disc of circular or octagonal outline, in Discalia
(fig. 4) relatively thick and small, in Disconalia (fig. 10) broader and flatter. Its
horizontal diameter is two to four times as great as its vertical main axis, and of the
same length as that of the pneumatocyst above it. Its peripheral margin is surrounded
by the corona of gonostyles, whilst its inferior face is in contact with the central siphon.

The entire mass of the lenticular centradenia is composed, in the Discalidae, of
numerous densely aggregated exodermal cells and cnidocysts, and many of these are (in
the well-preserved spirit specimens of the Challenger collection) filled with an air-bubble ;
it is therefore very probable that these cells secrete the gas, which is taken up by the
open distal ends of the tracheae, and conducted by these into the chambers of the
pneumatocyst. These gas-producing exodermal cells are probably derived from the basal
part of the pneumatosaccus, or the invaginated lamella of the exoderm which includes
the pneumatocyst. The thin structureless supporting plate, which separates the upper
face of the centradenia from the overlying pneumatosaccus, is pierced by numerous pores
which permit a direct connection between the two.

The solid exodermal parenchyma, in the Discalidee, is only traversed by the trachese,
and not by the so-called " liver-canals," which form a complex network in the Porpitidse
and Velellidse. These hepatic canals are here confined to an octoradial " liver-star,"
which lies in the superior face of the centradenia. The eight main rays of it lie in the
eight perradial grooves between the eight interradial triangular air-chambers, and are
united in the centre of the lower face of the central chamber. They arise from the basal
part of the eight subumbrellar radial canals (near their opening into the base of the central
siphon), and embrace the surface of the centradenia like eight equidistant meridional
arches. They remain single in Discalia (fig. 4), whilst they are forked and branched
dichotomously in Disconalia (fig. 10).

Gonostyles. — The polypites (or secondary manubria) which produce by budding the
medusiform gonophores are in the Discalidse mouthless palpons, and not siphons pro-
vided with a mouth, as is the case in the nearly allied Porpitidaa and the more divergent
Velellidse ; but also in the latter two families the gonostyles arise from the subumbrella
in the same mouthless form, and accpure their mouth opening later. Their structure is
the same as in the palpons of the Discalidaa. These are spindle-shaped or pyriform,
much smaller than the central siphon ; they form a regular simple corona around the
base of the latter. Discalia (PI. XLIX. figs. 1, 3) possesses eight, and Disconalia

REPORT ON THE SIPHONOPHORiE. 45

(PL L. figs. 1, 2) sixteen gonostyles. The medusiform gonophores arise from their
proximal part either isolated or in clusters (compare p. 37 above).

Tentacles. —The corona of submarginal tentacles exhibits in the Discalidce very inter-
esting forms, since these organs correspond in the two genera of this family to those of
two important larval stages of the Porpitidae. Discalia (PI. XLIX. figs. 1, 4) possesses
only eight simple radial tentacles of cylindrical form, which bear no lateral branches, but
a simple terminal cnidosphere (or a spherical knob composed of radially disposed cnido-
cysts). The larva of the other genus, Disconalia, also exhibits in its young state eight
simple tentacles (PL L. fig. 9), and hereafter at their distal end a group of four terminal
cnidospheres (fig. 10). These become multiplied in older larvae, and form a subumbrellar
corona inside the limb of the umbrella. The adult Disconalia (PL L. fig. 1) possesses
two rows of tentacles, in which eight perradial bunches are prominent. Each tentacle is
cylindrical, with club-shaped distal end, and bears in its distal half three longitudinal rows
of pediculate cnidospheres, an odd inferior and two paired lateral series (compare p. 38).

Ontogeny. — The individual development of the Discalidse is not known, but is probably
identical with that of the Porpitidae (compare p. 39).

Phytogeny. — The phylogenetic value of the Discalidse is, in my opinion, very great.
I regard Discalia as a survival of the common ancestral form of all Disconectae, and
Disconalia as an intermediate form between this and Porpalia.

Synopsis of the Genera of Discalidse.

Umbrella with eight simple tentacles. Pneumatocyst without concentric ring-chambers, . 1. Discalia.
Umbrella with numerous tentacles, arranged in eight radial bunches. Pneumatocyst with

concentric ring-chambers, surrounding the octoradial central disc, . . .2. Disconalia.

Genus 1. Discalia,1 Haeckel, 1888.

Discalia, Hkl., System der Siphonophoren, p. 29.

Definition. — Discalidse, with a lenticular or subglobular umbrella, including a lenti-
cular pneumatocyst, which is composed of a central chamber and eight surrounding
radial chambers, without concentric ring-chambers. Marginal tentacles eight, simple,
with a terminal cnidal knob.

The genus Discalia is the simplest and most primitive form of all Disconectae, and
may be regarded as one of the common ancestral forms of this order. It may be com-
pared to an octonemal Trachomedusa (Trachynema, Mdrmanema, Rhopalonema), which
has developed an octoradial pneumatophore in its exumbrella, and in which the eight
simple genital sacs of the subumbrella have been replaced by eight palpons or mouthless
gonostyles, which afterwards produce medusiform gonophores by budding.

1 Discalia = marine disc, 01'sx.o;, £>.ios.

46 THE VOYAGE OF H.M.S. CHALLENGES.

All Porpitidae probably pass during their metamorphosis through a larval stage,
which is essentially identical with Discalia, and differs from it only in the absence of
sexual palpons or gonostyles, bearing gonophores. The young larva of Porpita linnseana,
which Alexander Agassiz has figured,1 exhibits a larval stage which is a little more
advanced, and forms the transition to the Disconalia-stage.

The phylogenetic importance of Discalia, therefore, is very great. On the one hand,
it seems to indicate clearly the origin of the Disconectse from the Trachomedusse (Trachy-
nemidae) ; on the other hand, all the other Disconectse may be derived from it as from a
common ancestral genus.

Two species of Discalia, both inhabitants of the deep sea, were found by me in the
Challenger collection. The first species, Discalia medusina, was taken in the centre of the
Southern Pacific, at Station 288 (depth, 2600 fathoms), and is figured in PI. XLIX. figs.
1-6. The second species, Discalia primordialis, was captured in the tropical Pacific, at
Station 274 (depth, 2750 fathoms). The latter is distinguished from the former by a more
flattened umbrella, and by eight longer (perradial) tentacles, between which eight shorter
(interradial) were interpolated ; but as its state of preservation was not sufficient, I give
here only the description of the first well-preserved species.

Discalia medusina, n. sp. (PL XLIX. figs. 1-6).

Habitat— Southern Pacific, Station 288, October 21, 1875; lat. 40° 3' S., long.
132° 58' W.; depth, 2600 fathoms.

Umbrella (fig. 1, view from below ; fig. 2, from above ; fig. 3, in profile ; fig. 4, in
meridional section). — The umbrella, which represents the nectosome, is subspherical,
0"2 to 0"4 mm. in diameter. A deep annular constriction separates the flatter exumbrella
from the inflated and highly vaulted subumbrella. The latter bears in its equatorial
zone a corona of eight simple tentacles, and beyond it a corona of eight gonostyles,
which surround the central siphon.

Exumbrella (fig. 2). — The superior or apical face of the umbrella is rather flat, and
exhibits an octoradial star of brown pigment, indicating the course of the eight per-
radial exumbrellar canals, or the superior vessels of the mantle. The apical stigma, or the
superior opening of the central air-chamber, is situated in the centre of the pigment-
star, whdst eight ether stigmata, the outer openings of the eight interradial air-
chambers, are placed between the eight rays of the dark pigment-star.

Limbus Umbrella? (uu). — The circular margin of the umbrella is thickened and divided
by eight perradial incisions into eight prominent flat interradial lobes. The whole
margin is beset with a corona of the usual marginal glands (fig. 6) (compare p. 42 above).

1 57, pi. ix. figs. 1, 2.

REPORT ON THE SIPHONOPHOR^E. 47

Subumbrella (fig. 1). — The inferior or basal face of the umbrella is nearly hemi-
spherical. Its centre is occupied by the central siphon (sa), and this is surrounded by a
corona of eight gonostyles (gs). The equatorial zone of the subumbrella is beset with
eight perradial tentacles, and between these proceed outside the eight interradial lobes of
the limbus.

Pneumatocyst (fig. 2, pf, from above ; figs. 4, 5 in meridional section). — The central
air-chamber (pli) is spheroidal, large, and occupies about half the volume of the float.
A prominent tubular stigma (figs. 4, 5, po) opens in the centre of its upper face. The
eight radial air-chambers, which surround the former as a regular corona (pq), are
crescentric, concave on the axial side, convex on the abaxial side ; each opens by a stigma
on the upper face (pe). The pneumatocyst possesses only eight simple tracheae {pi), one
arising from the inferior face of each radial chamber ; the eight tracheae descend obliquely
and contorted downwards, enter into the centradenia (fig. 4, uc), and terminate in it : but
they do not pass into the exodermal wall of the central siphon.

Centradenia (fig. 4, uc). — The large central gland is a circular disc, the diameter of
which is about three to four times as great as its height, and equals that of the
pneumatocyst. The inferior face of the latter is in close contact with the superior face
of the former ; whilst the inferior face of the centfiadenia is separated by a thick support,
the gastrobasal plate, from the base of the central siphon. The whole mass of the
solid centradenia is composed of exoderm cells. Its entodermal system of hepatic vessels
is confined to an eight-rayed star on its superior face. The eight radial canals, which are
connected in the centre of the latter, arise from the proximal third of the eight sub-
umbrellar radial canals which run from the base of the central siphon towards the margin
of the umbrella. This simplest form of the gastro-hepatic canal-system gives the explana-
tion of its more complex form in the other Disconectse.

Central Siphon (figs. 1-4, sa). — The central polypite is a thick-walled contractile tube,
inversely conical in the proximal half, cylindrical in the distal half. Its length about
equals the equatorial diameter of the umbrella, and is twice as great as the diameter of
its base. The thick muscular wall is composed of a strong outer layer of exodermal
longitudinal fibres, and a thin inner layer of entodermal circular fibres, both separated by
a structureless elastic fulcrum. The distal mouth is octolobate.

The gastrobasis, or the horizontal roof of the stomach, is regularly octagonal, separated
by a thick fulcrum, the gastrobasal plate, from the centradenia above it. It is pierced in
the periphery by the gastral openings of the eight radial main vessels. These give off
branches for the gonostyles and tentacles, and run centrifugally in the subumbrella
towards the limbus, where they are united by a marginal ring-canal.

Gonostyles (figs. 1-4, gs). — The eight sexual palpons are about half as long and broad
as the central siphon. They bear clusters of gonophores in their cybndrical basal part,
patches of cnidocysts in their spindle-shaped distal part.

48 THE VOYAGE OF H.M.S. CHALLENGER.

Tentacles (figs. 1-4, t). — The eight tentacles are cylindrical, somewhat larger than the
diameter of the umbrella, and bear a single cnidosphere at the distal end.

Genus 2. Disconalia,1 Haeckel, 1888.

Disconalia, Hkl., System der Siplionoplioren, p. 30.

Definition. — Discalidse, with a lenticular or discoidal umbrella., including a discoidal
pneumatocyst, which is composed of a central chamber, eight surrounding radial chambers,
and several concentric ring-chambers. Marginal tentacles numerous, arranged in eight
radial bunches.

The genus Disconalia is closely allied to the preceding ancestral genus Discalia; but
it differs from it in the multiplication of the marginal tentacles, which form eight marginal
bunches ; and mainly in the peripheral increase of the octoradial pneumatocyst, which
is surrounded by several concentric ring-chambers. It corresponds therefore to that
larval stage of the Porpitidse which Alexander Agassiz ~ has figured of Porpita linnsena.
The young larvae, probably of all species of Porpitidse, after having passed the Discalia-
forrn, assume a transitional Disconalia-form.

Perhaps even Eschscholtz observed a Disconecta belonging to this genus. The
interesting small form, taken in the tropical Pacific, which he figures under the name
Porpita ramifera? is either a true Disconalia, or the corresponding larva of some
Porpitid passing through this typical stage. The answering of this question is not
possible, since the organs of the subumbrella, which would be decisive, are neither
figured nor even mentioned in the description given by Eschscholtz.

Two species of Disconalia (both deep-sea inhabitants) were found by me in the
Challenger collection, one from the Southern Pacific (Station 181), the other from the
Indian Ocean, south of Australia (Station 157). The latter (Disconalia pectyllis) had
much longer and less ramified tentacles, and a larger pneumatocyst, than the former
(Disconalia gastroblasta) ; but its state of preservation was not sufficient for a full
description. Regarded from a phylogenetic point of view, Disconalia is of the highest
importance as a necessary connecting link between Discalia and Poipalia. It is
derived from the ancestral genus Discalia by the multiplication of the air-chambers and
the tentacles ; if its gonostyles acquired a mouth, it would pass into Porpalia,

Disconalia gastroblasta, n. sp. (PI. XLIX. figs. 7-12; PI. L. figs. 1-10).

Habitat. — Southern Pacific, north-east of Australia, Station 181, August 25, 1874 ;
lat. 13c 50' S., long. 151° 49' E. ; depth, 2440 fathoms.

1 Disconalia, derivative from Discalia. - 57, pi, ix. lig. 3. 3 1, p. 17, Tat'. 16, figs. 3a, 36.

REPORT ON THE SIPHONOPHOR-ffi. 49

Umbrella (PL L. fig. 1, from below). — The umbrella is slightly vaulted, lenticular,
nearly cliscoidal, 4 to 6 mm. in diameter ; its vertical axis is about 1 mm. The margin
is regularly octolobate, with eight deep margiual incisions, from which arise the eight
bunches of tentacles.

Exumbrella (PI. XLIX. fig. 7). — The superior face of the umbrella is rather flat, a
little vaulted, and exhibits a regular network of brown pigmented canals, the exumbrellar
vessels. Eight regular radial canals arise from a central circular canal, in the centre of
which is placed the apical stigma of the pneumatocyst. The eight interradial chambers
of the latter are separated by these perradial mantle canals, which anastomose outside
and form a ring around each chamber. From this ring arise in each octant four to
six centrifugal canals, which are forked and prolonged outside the pneumatosaccus
into the exumbrellar canals of the limbus. Their dichotomous branches are connected
by anastomoses. A few peripheral stigmata are scattered in the outer half of the
exumbrella.

Limbus Umbrellas (fig. 7, um). — The free margin of the umbrella, outside the corona of
tentacles, is distinctly octolobate, and bears a series of pyriform marginal glands on its free
edge. The eight interradial convex lobes are more or less prominent between the eight
perradial bunches of tentacles.

Subumbrella (PL XLIX. fig. 11). — The inferior face of the discoidal umbrella is more
convex than the superior, and is divided into four different zones. The central zone is
occupied by the large central siphon (sa). This is surrounded by a corona of sixteen
gonostyles, and this by an octagonal tentacular zone (fig. 12, tu). Outside the latter
is prominent the broad octolobate limb of the subumbrella.

Pneumatocyst (fig. 8, half of the inferior face; fig. 9, half of the superior face). — The
subspherical central chamber (ph) possesses an apical stigma in the centre of its upper
face, and is surrounded by a corona of eight equal triangular radial chambers, each of
which bears a circular stigma. This octoradial central disc is surrounded by a peripheral
girdle composed of eight or nine concentric ring-chambers ; the second and third of these
(pk) are the broadest, much broader than the peripheral chambers. Eight deep perradial
furrows of the lower face separate the eight chambers of the octoradial ring one from
another, and are prolonged up to the circular margin of the pneumatocyst, dividing it
into eight slightly prominent lobes. In the middle between each two furrows (therefore
in eight interradial rows) may be seen the pneumathyrae, or openings by which the
concentric ring-chambers communicate one with another (fig. 8, pg).

The superior or apical face of the discoidal pneumatocyst (fig. 9) is slightly convex,
and bears about twenty stigmata, viz. , one central, eight interradial (in the middle of the
eight triangular chambers), and eight to twelve peripheral, irregularly placed in the second
to the fourth ring-chamber.

The inferior or basal face of the pneumatocyst (fig. 8) is slightly concave, and bears

(ZOOL. CHALL EXP. — PART LSXVII. — 1888.) Hbhh 7

50 THE VOYAGE OF H.M.S. CHALLENGER.

between fifty and ninety short trachea) (six to twelve in each octant). These are placed
in the periphery of the octoradial ring, and in the two to four next following chambers ;
they are wanting in the periphery.

Centradenia (figs. 10-12, uc). — The large central gland, or so-called "liver," is an
octagonal, lenticular, biconvex disc, of the same horizontal diameter as the overlaying
pneumatocyst. Its thickness is inconsiderable, and decreases towards the periphery.
Its convex superior face (fig. 10) is in close contact with the concave inferior face of the
latter. The peripheral octagonal margin of the centradenia does not exceed that of the
covering pneumatocyst.

The inferior face of the centradenia is rather flat, and is separated by a thin fulcrum
from the subumbrella. Its central part is in contact with the gastrobasal plate of the
central siphon ; its peripheral part with the corona of gonostyles, and its margin with the
corona of tentacles.

The structure of the centradenia exhibits in Disconalia the same remarkable simplicity
and typical form as in Discalia. The solid parenchyma is entirely composed of masses
of aggregated exoderm-cells, with innumerable cnidocysts. A regular octoradial star
of pigmented hepatic vessels is placed on its superior face (fig. 10). From the centre of
the latter arise eight perradial brown " fiver-canals," which branch dichotomously, and
run on its upper face towards its peripheral margin. They pass here over into the
peripheral canal-network of the subumbrella, from which arise the canals of the tentacles
and gonostyles.

Central Siphon (PI. L. figs. 1, 3). — The large central polypite has the usual form
of an inverted cone. The broad octagonal base occupies the central area of the sub-
umbrella, and is separated from the centradenia above it by the gastrobasal plate. The
periphery of the base opens by eight perradial ostia (PL XLIX. fig. 12) into the eight
radial main vessels which run in the subumbrella towards the limb, and give off the
ascending centripetal canals of the " liver-star " (fig. 10).

The muscular wall of the central siphon is very thick. It opens by a distal octolobate
mouth, the edges of which are strongly armed with cnidocysts (PL L. fig. 3).

Gonostyles (PL L. figs. 1, 2). — Sixteen sexual palpons, or mouthless gonostyles, form a
corona around the base of the sterile central siphon. They are small spindle-shaped sacs,
scarcely half as long as the central siphon. Their wider basal half bears clusters of
gonophores (fig. 2, g), whilst the slender distal half is beset with cnidonodes (k) ; the
closed distal end is obtusely conical and entirely covered by cnidocysts.

Tentacles (PL L. figs. 1, 4-G). — The tentacles are very numerous and densely
crowded in the subumbral groove between the corona of gonostyles and the limb of the
umbrella. They alternate here in a double row (PL XLIX. figs. 1, 2). The tentacles
which arise from the eight perradial corners of the octagonal girdle are much longer than
the interjacent interradial, and form therefore eight prominent bunches.

REPORT ON THE SIPHONOPHOR^. 51

The structure of the cylindrical tentacles is the same as in all Porpitidse. They bear
three rows of pecliculate cniclospheres in their club-shaped distal half, one inferior and two
opposite lateral rows (figs. 4-6).

Family II. Poepitid^, Brandt, 1835.
Pm-pitidx, Brandt, Prodromus, 25, p. 40.

Definition. — Disconectse with a circular permanent umbrella, including a campanu-
late or discoidal pneumatocyst, which is composed of an octoradial centre and numerous
concentric rings, without vertical crest. No vertical sail upon the umbrella. Submarginal
tentacles with three rows of pediculate cniclospheres. Central siphon surrounded by
numerous peripheral fertile siphons, which bear the gonophores.

The family Porpitida?, founded in 1835 by Brandt for the genus Porpita, comprises
all those Disconectse polygastricse which have a circular umbrella and a regular
originally octoradial ground-form. They agree in their regular octoradiate form with
the monogastric Discalidse, their ancestral group, but differ from them essentially in the
polygastric structure which they share with the Velellidse. Not only does the primary
sterile central siphon possess a mouth opening at its distal end, but likewise also each of
the surrounding gonostyles. These peripheral polypites, which bear the gonophores
budding from their proximal part, are therefore not mouthless palpons (as in the
Discalidse), but mouth-bearing, feeding, and digesting secondary siphons. The Velel-
lidse, with the same polygastric organisation, differ from the Porpitidse in the amphi-
thect or bilaterally-radial type, and in the development of a vertical sail upon the
exumbrella.

Eschscholtz, in his fundamental work,1 described five different species of Porpitidse,
which he united in the single genus Porpita. Lesson 2 added to this two other genera
(each with a single species), Ratis and Acies. His description, however, is very incom-
plete, and not illustrated by any figure, so that it is impossible to decide whether they
are merely young forms of Porpita (as most authors suggest) or perhaps Discalidse.

Some interesting new Porpitidse, found in the Challenger collection, and some other
new forms observed by myself on different occasions, have led me to divide this family
into four genera (characterised in my System).3 These may again be disposed in two
subfamilies, the Porpalidse and the Porpitellidse, each with two genera. The first
subfamily, Porpalidse, has a lenticular or subglobular umbrella and a campanulate
pneumatophore with lobate margin {Porpalia and Porpema) ; whilst the second sub-
family, Porpitellidse, possesses a flat discoidal umbrella and a medal-shaped pneumato-
phore with a circular, not lobate margin {Porpitella and Porpita).

Umbrella. — The complete body of all Porpitidse is circular, sometimes more lenticular

1 1, 1829, p. 176. 2 3, 1813, p. 592. 3 95, 1888, p. 30.

52 THE VOYAGE OF H.M.S. CHALLENGER.

or subglobular (in the Porpalidae), sometimes more flatly expanded or discoidal (in the
Porpitellidae). Its vertical main axis is in the first case little shorter or nearly as long
as the horizontal or equatorial axis ; whereas in the second case it is much shorter,
only one-half or one-third as long, or even less. The free promine ntmargin, or the
glandiferous limbus umbrellas, marks the boundary between the exumbrella (upper or
pneumatophorous half) and the subumbrella (lower or siphonophorous half).

Exumbrella. — The upper, apical or proximal, part of the discoidal trunk, which
corresponds to the exumbrella of the Medusae, and physiologically represents the
nectosome, is in all Porpitidae circular and composed of the pneumatocyst, filled with
gas, and the surrounding pneumatophore. This latter is composed of two parallel
membranes, separated by a network of anastomosing radial canals — the outer thicker
membrane armed with thread-cells and pierced by the stigmata, is the pneumatocodon ;
the inner thinner membrane, immediately including the pneumatocyst, is the pneumato-
saccus or the invaginated exoderm. Both membranes are connected by numerous branched
radial septa, and the cavities between these, radiating from the centre of the disc, are
the radial canals of the exumbrella (pallial vessels) ; they open at the margin of the
disc into the large circular canal of the limb.

The surface of the exumbrella is in many Porpitidae smooth, in others more or less
papillate, owing to conical protuberances of the pneumatocyst. Often an elegant? multi-
radiate pigment-star is visible, produced by a dark pigment in the wall of the pallial
vessels. The central part of the exumbrella in all Porpitidae is pierced by a central
stigma, and a surrounding corona of eight stigmata placed in the walls of the eight
surrounding radial chambers. The other stigmata of the exumbrella, in larger species
several hundreds, in smaller only few, are sometimes disposed in regular radial rows, at
other times more irregularly scattered.

Pneumatocyst. — The chitinous polythalamous float filled with gas, which is called
pneumatocyst (formerly "inner shell"), is in the Porpitidae always regularly circular,
corresponding to the surrounding pneumatosaccus (or the invaginated exumbrella) from
which it is secreted. Consequently its general form in the subfamily Porpalidae is highly
vaulted, campanulate or cap-shaped [Porpalia, Porpema, Pis. XL VTL, XL VIII. ), whereas
in the flatly expanded Porpitellidae it is discoidal, even or slightly vaulted {Porpitella
and Porpita, Pis. XLV. and XLVL). The pneumatocyst is always composed of two
little distant and nearly parallel lamellae of structureless chitin, which are connected
by numerous concentric annular septa. The latter divide the float into numerous
concentric ring-chambers, and these open on the upper or proximal face by stigmata,
on the lower or distal face by tracheae.

The central disc of the pneumatocyst has in the Porpitidae the same structure as in
the Discalidae ; it is composed of a spherical or subglobular central chamber (with a
central stigma above) and of eight equal triangular radial chambers, each of which bears

REPORT ON THE SIPHONOPHOR^E. 53

a stigma above, and a trachea (or a bunch of trachese) below. This evident octo-
radial structure of the central part is often lost in the peripheral part of the pneuma-
tocyst.

The concentric ring-chambers which compose the latter are simple circular rings,
without radial septa. Their number is very variable, in the smaller species ten to
twelve, or even less, in the larger species forty to sixty, and in the largest more than a
hundred. They are usually of nearly equal breadth ; often, however, the chambers of
the middle part are wider than the more proximal (near the centre) and the more distal
chambers (near the margin). The first or innermost of the concentric ring-chambers is
different from all others ; it embraces the octoradial central disc not only from the outer
(abaxial) but also from the lower (basal) side (PI. XLVL figs. 3, 6).

Pneumothyrse. — It is a general opinion that the concentric circular ring-chambers
of the Porpitidse are perfectly separated one from another by solid annular septa. But
this is not the case. I found in all members of this family openings of communication
between them, which I shortly call pneumothyrse. The thin chitinous annular septa,
which separate the ring-chambers, are concave on the axial side, convex on the abaxial
side, they are usually thicker in the upper, thinner in the lower, part. Each annular
septum is pierced in its basal part by at least eight pneumothyrse, ovate or roundish
openings, which are about twice as broad as the stigmata of the upper surface. The
pneumothyrse or ring-gates (PI. XLVL figs. 3, 4, pg) be originally in the same radii as the
stigmata (pe). There are, therefore, eight interradial rows of pneumothyrse. But in the
larger species their number is increased, accessory pneumothyrse being interpolated
between the primary ones in the outer chambers.

The superior, proximal or apical side of the pneumatocyst is usually flat in the
central part, whilst the peripheral part is highly convex or campanulate in the
Porpalidse, slightly convex or even in the Porpitellidse. Its surface is sometimes smooth,
at other times rough and marked by radial stripes or ribs, aud by concentric circles.
It is sometimes, mainly in the central part, spiny, papillate, or armed with conical,
irregularly scattered tubercles. The chitinous substance in the central part is often
much thickened by apposition of secondary layers, and these may close the stigmata of
that part. Those of the peripheral part remain always open.

The stigmata, or the pneumatic foramina on the upper face of the pneumatocyst (pe),
are much more numerous in the Porpitidse than in the Discalidse and Velellidse. Constantly
there is a central stigma in the apex of the central chamber, and around this a regular
corona of eight equidistant stigmata in the eight radial chambers which surround the
former. The other stigmata are usually not regularly disposed, but scattered in great
numbers over the upper surface. When the latter is provided with radial ribs or
prominent ridges, the stigmata are placed in the height of the ridges, not in the valleys
between them. The stigmata are sometimes simple openings in the upper wall of the

54 THE VOYAGE OF H.M.S. CHALLENGER.

ring-chambers. But usually they are dilated in the middle, more or less urn-shaped,
and sometimes prolonged into short prominent tubules (PL XL VIII. fig. 8, pe).

The inferior, distal or basal side of the pneumatocyst, separated by the exodermal
epithelium of the pneumatosaccus from the neighbouring superior face of the centra-
denia, corresponds in its general form to the latter, and has therefore a more complicated
shape than its superior face. It is always more or less concave, hemispherical or
campanulate in the Porpalidae, slightly concave or cap-shaped in the Porpitelkdae.
Numerous radial ridges or folds are prominent from the inferior face of the float, and
often these arise in the form of vertical radial lamella?, separated by deep valleys. These
latter are filled up by corresponding high radial ridges of the upper face of the centra-
denia. The number of the radial ridges increases rapidly towards the periphery,
numerous secondary and tertiary centripetal lamellae (which do not reach the centre)
being interpolated between the centrifugal primary ones. The concave under surface of
the pneumatocyst, and the convex upper surface of the centradenia, catching one into
another, become very similar to a Fungia (PI. XLVIII. fig. 7). From the combs of
the prominent radial ridges arise the tracheae (fig. 6, pt).

Tracheae. — The pneumatic tubules or aeriferous filaments, which we call shortly
trachea?, are much more numerous in the Porpitida? than in the Discalida? and Velellidae.
Each radial ridge bears in the larger species on an average more than one hundred tracheae,
and as the number of the ridges there amounts to some hundreds, the number of the
tracheae reaches many thousands. The innermost tracheae, nearest the main axis, arise
from the eight radial chambers which surround the central chamber. The other tracheae
arise sometimes isolated, in irregular radial series, from the crest of the ridges, at other
times in bunches, crowded in small groups of three to six or nine, rarely more.

The aeriferous tubules are usually simple, very rarely branch, and never anastomose.
Their thin chitinous wall is cylindrical, of very different length. Their course is never
straight, always more or less curved, and often serpentine. The trachea? of all Porpitidae
are distinctly articulate, and seem to be composed of a series of short truncate conical
segments ; the distal or inferior end of each segment is wider (PI. XLVI. fig. 8).
Sometimes each segment seems to be separated from the other by a transverse septum ;
but the apparent septum is merely an annular constriction. The two ends of each ring-
segment (proximal and distal) remain always open.

The course of the tracheal is difficult to make out. Descending from the lower face of
the pneumatocyst, they enter immediately into the centradenia, and run in sinuous curves
between the canal-network of this organ. A great part finishes inside the central gland,
whilst another part descends deeper and passes into the wall of the central siphon and
the peripheral siphons. They end here in the exoderm of the proximal half of the
siphons, and do not enter into their distal half. Usually the great majority of the
trachea? are much shorter than the vertical diameter of the centradenia ; they must there-

REPORT ON THE SIPHONOPHOPwE. 55

fore finish in the solid glandular parenchyma of this latter, and cannot pass through it
and enter into the wall of the siphons. A small part only of the tracheae enters into this
latter. The distal ends of all tracheae are open, surrounded by exodermal epithelia,
as in the other Disconectae. No tracheae are found in the marginal tentacles, nor in the
peripheral part of the umbrella outside the centradenia.

The margin of the pneumatoeyst is circular and not lobate in the flat discoidal Porpi-
tellidae, whilst it is divided into numerous radial lobes in the campanulate Porpalidae ; the
lobes are here sometimes small, sometimes widely prominent. Their number is originally
eight or sixteen, and by furcation thirty-two or sixty-four (PI. XLVIII. figs. 4, 5).

Central Siphon. — The large central polypite of the Porpitidos is not different from
that of the Discalidae, a thick-walled and very contractile tube of very variable form.
Usually it is inversely conical, its diameter decreasing gradually from the broad proximal
base towards the distal mouth. Sometimes the upper half, or the stomach, is ovate and
much wider than the lower half, or the cylindrical proboscis. Its transverse section is
either circular or octagonal, in consequence of eight prominent radial folds. In some larger
species the outer wall exhibits sixteen longitudinal folds instead of eight, and sometimes
eight larger (perradial) and eight smaller (interradial) ribs alternate. To these correspond
the same number of internal furrows at the inside of the siphon. These furrows lead into
the basal openings of the stomach, in which the primary radial canals open (eight or
sixteen). The basal ostia form a regular corona ; in some larger species their number is
increased, numerous secondary and tertiary ostia being intercalated between the eight
primary ones. The base of the stomach is separated completely from the overlaying
centradenia by the structureless sobd gastrobasal plate.

Centradenia. — The large central gland, or the so-called " central organ" (formerly
"fiver"), exhibits the peculiar composition described above (p. 31). In the Porpitidae
it is much more voluminous than in the Discalidae and Velellidas, and occupies the whole
space between the inferior face of the pneumatophore and the superior face of the sub-
umbrella which bears the siphons. The central gland is largest in some lenticular or
subglobular Porpalidae, where its weight and volume are greater than those of all other
parts of the body together ; it is relatively smaller in the flat discoidal Porpitellidae.
The dense network of canals in the central gland is in its upper brown or blackish half
composed of hepatic vessels (with biliary epithelium), in its lower green or whitish half of
renal vessels (with epithelium secreting guanin crystals). The compact exodermal epithe-
lium filling up the intervals of the canal-network contains masses of cnidoblasts and
probably secretes the gas, which enters into the open distal ends of the tracheae.

Gonostyles. — The numerous polypites of the subumbrella, which produce by budding
the medusiform gonophores, in the Porpitidae are not mouthless palpons as in the Dis-
calidae, but mouth-bearing siphons as in the Velellidae. They are, therefore, usually called
" smaller polyps, sexual polypites, or peripheral siphons" (shortly " perisiphons"). They

56 THE VOYAGE OF H.M.S. CHALLENGER.

either form a simple ring of eight or sixteen gonostyles around the central siphon, or
they occupy a broader gonostylar zone, often the whole suburnbrella between the central
siphon and the submarginal corona of tentacles. At first there is a corona of eight
gonostyles only, regularly placed around the central siphon, and this state is permanent in
some species of Porpalia (PI. XLVIIL). In Porpitella (PL XLVI.) there is a girdle of
sixteen gonostyles. But usually their number is soon increased, and they form several
concentric circles, more or less regular. Finally, in the largest Porpitidse their number
amounts to several hundreds, and they are densely crowded. Their form and structure
have been described above (p. 36).

Tentacles. — The corona of submarginal tentacles in all Porpitidse is originally
regularly octoradial. In all young larvae of this family there occurs a stage in which the
umbrella-margin bears only eight tentacles regularly disposed at equal intervals (PI. L.
figs. 9, 10), as permanently in Discalia (PL XLIX. figs. 1-4). But their number is soon
increased either by interpolation of eight secondary interradial tentacles (in the middle
between the former), or by budding of several secondary tentacles at the base of each
primary one, so that eight regular bunches arise {Porpalia, PL XLVIIL). Sometimes
sixteen bunches are formed {Porpitella, PL XLVI.). Usually the number is so increased
that hundreds or thousands of tentacles, densely crowded, cover the whole zone beyond
the margin of the disc. Often three to nine or more concentric circles may be discerned,
and then the uppermost are the smallest, the lowermost the longest. Sometimes their
bases are so densely crowded in the tentacular area, that after removing the tentacles
there appears an elegant reticulated girdle beyond the margin ; each rhomboidal dimple
of the reticulum is the place of the basal insertion of a lost tentacle (PL XL VII.
fig. 3, tu; PL XLVIIL fig. 2, tu).

The, general structure of the tentacles is the same in the Porpitidse as in the other Dis-
conectse ; but they differ from those of the Velellidse in their peculiar constant form and
structure. The youngest larvae of the Porpitidse bear eight simple radial tentacles with a
terminal cnidosphere (PL L. fig. 9) like those of Discalia. The next larval stage exhibits
four pediculate cnidospheres at the distal end of each tentacle, one of which is the primary
terminal knob, the three others basal branches of it (fig. 10). The number of the latter
is soon multiplied, and the older and longer tentacles, which are club-shaped and
thiekened at the rounded distal end, bear always three longitudinal rows of pedunculated
cnidospheres ; one odd inferior series in the middle line of the lower or distal face, and two
paired (lateral) series on the two lateral faces ; the upper or proximal face is always smooth.1
Each cnidosphere is a thin lateral branch of the tentacle, having the same structure as
the latter, and bearing a terminal sphere composed of radially crowded cnidoblasts. The
peduncles of the latter are sometimes shorter, at other times longer. Their length often
increases towards the distal end of the tentacle. Their number is very variable in different

1 57, pis. ix., x.

REPORT ON THE SIPHON OPHOR^E.

57

species ; usually each of the three longitudinal rows bears six to nine branches, often
twelve to twenty or more (PI. L. figs. 1-6).

Ontogeny. — The individual development of the Porpitidae has hitherto been unknown.
I conclude, however, from the comparative morphology of the new Porpitidae and Disca-
lidee here described, that all members of these two families pass through a larval stage
very similar to Discalia, This is subject to a shorter or longer metamorphosis, and passes
through a stage similar to Disconalia. The transition from this to Porpalia, the simplest
form of Porpitidae, is easy to conceive. The gonostyles acquire a mouth, and so the
sexual palpons of the former are replaced by the sexual siphons of the latter.

The medusiform gonophores, which are produced from these gonostyles by budding,
have the same form and structure as the well-known Discomitra (afterwards CJirysomitra)
larvae of the Velellida?.1 They become sexually mature in the free medusoid state, after
having been detached from the gonophores. The larvae which arise from the fertilised
egg have not yet been observed.

Phytogeny. — The comparative morphology of the Porpitidae and Discalidae admits the
phylogenetic hypothesis that the former have arisen from the latter. When Disconalia
acquires a terminal mouth on the distal end of each blastostyle, it passes over into
Porpalia.

Synopsis of the Genera of Porpitidae.

I. Subfamily Porpalid.e.

Umbrella highly vaulted. Pneumato- -
cyst campanulate, with a radially
lobate margin.

Tentacles arranged in eight radial
bunches, the eight primary more promi-
nent, ......

3. Porpalia.

Tentacles very numerous, in a circular
corona, the eight primary not promi-
nent,

4. Porpema.

II. Subfamily Porpitellid^:.

Umbrella flat, slightly vaulted. Pneu-
matocyst discoidal, without pro-
minent radial marginal lobes.

Tentacles arranged in sixteen radial
bunches, the eight primary and the
eight secondary prominent, . . 5. Porpitella.

Tentacles very numerous, in a circular
corona, the eight primary not promi-
nent, ...... 6. Porpita.

Subfamily 1. Porpalid.e, Haeckel.
Genus 3. Porpalia,3 Haeckel, 1888.

Porpalia, Hid, System der Siphonophoren, p. 30.
Definition. — Porpitidae with a lenticular or subglobular strongly vaulted umbrella, in-
cluding a campanulate pneumatocyst with radial marginal lobes. Tentacles numerous,
arranged into eight or sixteen prominent radial bunches.

-"6^~ """' ^6'

1 57, pi. x. 2 Porpalia = Marine ring of a buckle, wo'jxu, &Km.

(ZOOL. CHALL. EXP. — PART LXXVlL — 1888.)

Hhhh 8

58 THE VOYAGE OF H.M.S. CHALLENGER.

The genus Porpalia and the following Porpema together make up the subfamily
Porpalidse, characterised by a strongly vaulted, lenticular or nearly spherical, umbrella,
which includes a mitriform or campanulate pneumatocyst ; the distal margin of the latter
being divided into radial lobes. The chitinous substance of this lobate pneumatocyst in
the Porpalidse is much thinner, more delicate, and softer than in the Porpitellidse (Por-
pitella and Porpita), sometimes it resembles crumpled tissue-paper. The numerous mar-
ginal tentacles in Porpalia are arranged in eight regularly disposed radial bunches,
whilst in Porpema they are equally distributed along the margin of the umbrella.

The genus Porpalia is founded upon a new species, Porpalia prunella (PI. XLVIIL),
well-preserved specimens of which were found in the Challenger collection, taken in
the tropical Pacific (Station 222). The incomplete description of another species of
this genus, founded upon a single specimen, was given in 1829 by Eschseholtz, under the
name Porpita globosa.1 He took this specimen in the tropical Atlantic, near the Cape
Verde Islands. The exumbrella is in this Atlantic Porpalia globosa much smaller, but
the tentacles larger than in our species from the Pacific.

The phylogenetic position of Porpalia is clearly indicated by its morphological relation
to Disconalia on one hand, and to the Porpula larvae of the other Porpitidte on the other.
It may be regarded as the common ancestral form of this family derived from Disconalia
by the formation of a mouth on the distal ends of the gonostyles.

Porpalia prunella, n. sp. (PI. XLVIIL).

Habitat. — Tropical Pacific, north of New Guinea, Station 222 ; March 6, 1875;
lat. 12° 15' N, long. 146° 16' E. Surface.

Umbrella (fig. 1, as seen from above ; fig. 2, in profile ; fig. 3, in meridional section).
— The umbrella is biconvex lenticular ; its diameter amounts to 4 or 5 mm. (without ten-
tacles and siphon). A deep submarginal ring-furrow separates the flat exumbrella from the
biconvex body, the superior face of which is more strongly vaulted than the inferior.
The equatorial diameter of the biconvex lens is twice as great as its vertical main axis.

Exumbrella (figs. 1-3, uc). — The superior or apical face of the umbrella is rather
flat, with a shallow ring-furrow separating the central disc from the elevated peripheral
margin. The central disc exhibits an elegant pigment-star with eight dark brown rays.
Numerous stigmata are disposed in irregular rows between them.

Limbus Umbrellte (figs. 1-3, um). — The free prominent border or limb of the umbrella
is as broad as the radius of the central disc of the umbrella, and therefore half as broad
as the equatorial radius of the lens. Its upper face is concave, the lower convex. The
thickened margin is reflected upwards, and contains a single series of the usual muci-
parous glands (compare above).

1 1, p. 178, Taf. 16, fig. 4.

REPORT ON THE SIPHONOPHORiE. 59

Subumbrella (figs. 1-3, iv). — The inferior or basal face of the umbrella exhibits
beyond the deep submarginal ring-furrow a broad naked girdle, in which the radial canals
ascend from the tentacular zone to the margin of the umbrella. The tentacular zone
begins in the equator of the biconvex lens, and occupies the peripheral half of its lower
convexity. Its breadth equals the radius of the central disc of the exumbrella.

Pneumatocyst (fig. 4, from above ; fig. 5, from below; fig. 3,p, in vertical meridional
section). — The float, filled with air, is campanulate, and envelops the subspherical centra-
denia, with exception of its basal centre, which is occupied by the central siphon. The
equatorial diameter of the pneumatophorous bell is twice as great as its vertical main
axis. The basal opening of the bell, closed by the base of the central siphon, is scarcely
greater than half its height. The concave inferior face (or the cavity of the bell) is in
close contact with the centradenia, and the thirty-two prominent radial crests of the
former fit into thirty-two deep radial furrows of the latter. The convex superior face
is flatly conical above the equator (itg) ; its peripheral girdle, beyond the equator, is
regularly divided into sixteen furcate radial lobes (or thirty-two smaller lobes).

The central chamber of the pneumatocyst is surrounded by a regular girdle of eight
radial chambers, each of which possesses a stigma on its upper, and a trachea on its
lower side. This octoradial girdle is surrounded by eight to ten complete, concentric,
circular ring-chambers, the outermost of which touches the equator of the lens. Outside
follows the peripheral girdle of thirty-two lobes, which is recurved inwards and down-
wards (horizontally expanded by pressure, see fig. 4). The superior or convex face of
the pneumatocyst bears in its superior central part (which is in contact with the exum-
brella) numerous radial rows of stigmata. From its inferior or concave face, which is in
contact with the centradenia, hang down thirty-two prominent radial crests, or rather
lamellar pouches (fig. 6) ; and from the lowermost part of the latter arise numerous long
tracheae which enter into the glandular tissue of the liver (fig. 3, uc) ; the majority of
them terminate here with open distal ends, whilst a small part of the tracheae enters into
the basal part of the wall of the siphons, and ends in its exodermal epithelium.

The chitinous substance of the thin wall of the campanulate pneumatocyst is very
delicate and richly folded, like crumpled tissue-paper.

Centradenia (fig. 3, uc). — The large central gland is nearly spherical, and entirely
fills up the subumbrellar cavity of the pneumatocyst. The circular polar area only of its
lower pole is in contact with the base of the central siphon. Besides this smooth inferior
area, the entire surface of the centradenia is traversed by numerous deep meridional
grooves, which are filled by the lamellar radial pouches of the basal face of the pneuma-
tocyst. The dense parenchyma of its exodermal cellular tissue is traversed by numerous
bent tracheae, and by a loose network of hepatic canals. The latter arise from a regular
octoradial star of superior liver-canals, which unite in the superior or apical pole of the
centradenia. These eight radial main canals embrace the greater part of its surface like

60 THE VOYAGE OF H.M.S. CHALLENGED.

eight meridional arches, and open on the periphery of its inferior polar area into the gastral
cavity of the central siphon. Their dichotomous branches run along the convex outer
surface of the centradenia, enclosed in the numerous radial folds which fit into the
corresponding meridional furrows of the subumbrellar face of the pneumatocyst.

Central Siphon (fig. 2, in profile ; fig. 3, in longitudinal section). — The large central
polypite is a thick-walled cylindrical tube, the length of which surpasses the vertical main
axis of the umbrella. Its distal end opens by a four-lobed mouth, whilst its proximal or
basal part is conically dilated and closed by the supporting plate separating it from the
centradenia (fig. 3). In the periphery of the latter open the eight radial main canals.

Sexual Siphons (figs. 2,3, sx). — A corona of eight sexual polypites surrounds the base
of the central siphon, and separates it from the tentacular zone. These are much smaller
than the central siphon (about half as long, and many times thinuer). Their thin cylin-
drical basal part is beset with numerous gonophores ; their spindle-shaped distal part
opens by a four-lobed mouth.

Tentacles (figs. 1-3, t). — The tentacles are very numerous, and occupy a broad convex
zone of the subumbrella, between its equator and the girdle of sexual siphons. After
removal of the tentacles, their insertion forms an elegant reticulate girdle, with rhom-
boidal meshes (fig. 2, to). The tentacles are arranged in four to five transverse rows,
and in eight prominent radial bunches ; the longest of each bunch surpassing the diameter
of the umbrella.

Genus 4. Porpema? Haeckel, 1888.
Porpema, Hkl, System der Siphonophoren, p. 30.

Definition. — Porpitidae with a lenticular or subglobular strongly vaulted umbrella,
including a campanulate pneumatocyst with radial marginal lobes. Tentacles very
numerous, equally disposed in several concentric circles, not forming radial bunches.

The genus Porpema has the same strongly vaulted umbrella and the same campanu-
late and radially lobate pneumatocyst as the preceding genus Porpalia, from which it
differs in the equal distribution of the tentacles along the whole margin of the umbrella.
The tentacles are very numerous and densely crowded in several parallel circles (as in
Porpita), and they are not grouped into radial bunches.

The new genus Porpema was established for an Indian species, Porpema lenticula,
which I observed in 1881 in the Indian Ocean, between Aden and Bombay. Another
species, described in the following pages as Porpema medusa (PI. XL VII.), was found in
the Challenger collection ; this was taken in the South Atlantic, Station 327 (between
Buenos Ayres and Tristan da Cunha). A third species [Porpema pileata) was sent me
from Chili ; it will be described in my Morphology of the Siphonophorse. •

1 Porpema = Mantle, cloth, wopx/ipx.

REPORT ON THE SIPHONOPHORjE. 61

Eegarding the phylogenetic origin of Porpema, we may simply assume that it has
been derived from the ancestral genus Porpalia, by multiplication and equalisation of
the submarginal tentacles, which form circular girdles, without octoradial arrangement.

Porpema medusa, n. sp. (PI. XLVIL).

Habitat.— South Atlantic, Station 327; March 4, 1876; lat, 36° 48' S., long.
42° 45' W. Surface.

Umbrella (fig. 1, from above; figs. 2 and 3, in profile, fig. 2 with tentacles, fig. 3
after removal of them ; fig. 4, meridional section). — The umbrella is nearly spherical, and
has a diameter of 4 to 6 mm. (without the tentacles and the siphon). In some specimens
the vertical main axis is somewhat shorter than the equatorial diameter, in other
specimens a little longer.

Exumbrella (figs. 1, 2, 3, ue). — The superior or apical face is slightly convex, cap-
shaped, with a flat annular furrow which separates the central disc from the elevated
margin, like a flat hat with a recurved brim. The central disc exhibits a dark pigment-
star with sixteen broad rays, and a greater number of finer rays between the dark
prominent main rays. A great number of stigmata is arranged in radial rows.

Limbus Umbrellas (figs. 1-4, uu). — The free prominent border or margin of the
umbrella is nearly horizontally expanded, and slightly reflected upwards, like the broad
brim of a flat hat ; it is concave above, convex below. The breadth of the margin equals
the diameter of the exumbrellar central disc, and half the ecmatorial diameter of the
subglobular umbrella. The thickened edge of the margin is beset with a series of the
usual muciparous glands (compare above).

Subumbrella (figs. 1-4, w). — The inferior or basal face of the umbrella exhibits
beyond the deep submarginal ring-furrow a narrow, smooth zone, which is radially
striped ; these stripes are the radial canals ascending from the corona of tentacles to the
margin of the umbrella. The broad tentacular zone of the subumbrella (fig. 3) is a
circular girdle, which embraces the equatorial zone of the whole umbrella ; its vertical
height equals the radius of the latter. After removal of the tentacles it appears elegantly
panelled (fig. 3, tu).

Pneumatocyst (fig. 7, from above ; fig. 8, from below ; fig. 4, p, in vertical section). —
The float, filled with air, is campanulate or nearly spherical, with a central opening at
the basal pole of its vertical main axis. The diameter of this inferior opening measures
1 mm., and is about one-third as great as that of the float (3 mm.). The spherical
outer surface of the pneumatocyst is in close contact above with the exumbrella, beyond
the equator with the tentacular zone of the subumbrella. The inner cavity of the

62 THE VOYAGE OF H.M.S. CHALLENGES.

campanulate double-walled float is filled up by the ceutradenia (uc), which passes through
its basal aperture (fig. 4).

An exquisite regular octoradial structure is visible in all parts of the pneumatocyst.
The central chamber (ph) is nearly cylindrical, with an apical stigma (po), and sur-
rounded by a regular corona of eight radial chambers (p>q), each with a stigma above
and a trachea below. The deep radial furrows between these eight lobes (fig. 7, pr) are
prolonged to the periphery of the pneumatocyst, which is divided into eight large main
lobes. Each of the latter is again divided by a median incision into two secondary lobes,
and these again into four tertiary lobules. Thus the entire peripheral part of the float,
beyond its equator, is radially lobate. The deep radial furrows of the superior face of
the pneumatocyst correspond to high prominent radial crests or lamellar pouches of
its concave lower face, and from the height of these lamellar crests arise numerous
tracheae entering into the centradenia. The double wall of the concentric ring-chambers
presents therefore a very large surface, by means of the strong development of these
radial folds.

Centradenia (figs. 6 and 9, transverse sections ; fig. 4, uc, meridional section). — The
large central gland exhibits in this Porpitid a strange cylindrical form, due to the
unusual development of the vertical or longitudinal axis ; the latter attains 3 to 4 mm.,
whilst the horizontal diameter of the cylindrical centradenia is only 1 to 1*5 mm. Its
middle part is constricted by the embracing inferior margin of the campanulate pneu-
matocyst. The radial lamellar crests of the latter fit into corresponding meridional
furrows on the surface of the upper head-like part of the centradenia. The lower
cylindrical part of this latter is surrounded by the corona of sexual siphons, and its
circular basal face is in contact with the basal plate of the sterile central siphon. From
the periphery of this plate arise eight radial canals, which are soon forked ; an outer
main branch runs outwards to the tentacular zone and the umbrella margin ; an inner
main branch ascends vertically between the convex outer surface of the centradenia and
the concave inner surface of the pneumatocyst. These eight centripetal liver-canals
unite in the apical pole of the central gland, and form here a regular "liver-star" (fig. 8,
cm) they give off numerous branches, which form a network in theexodermal parenchyma
of the liver ; between its branches numerous bent tracheae are visible.

Central Siphon (sh, figs. 2 and 3 in profile, fig. 4 in vertical section, fig. 5 from below,
fig. 10 in transverse section). — The large central polypite has an upper pear-shaped part
(stomach) and a lower cylindrical part (proboscis). Its length is, in the contracted state,
equal to the diameter of the spherical umbrella, and twice as great as its greatest hori-
zontal diameter (near the base). Its thick muscular wall exhibits eight longitudinal
exodermal furrows on the outside, and eight corresponding radial entodermal folds on the
inside (fig. 10). Between these folds open in the basal part the eight radial canals
(fig. 9, sf). The distal mouth has eight radial lappets (figs. 3, 4, so).

REPORT ON THE SIPHONOPHORvE. 63

Sexual Siphons (sx, figs. 2-5). — A great number of sexual polypites, densely-
crowded and arranged in four to five concentric rings, occupies the broad basal zone of
the subumbrella, between the central siphon and the corona of tentacles ; their number
may be between sixty and ninety in the smaller, two hundred to three hundred in the
larger specimens. The form of these contractile gonostyles is very variable, usually
spindle-shaped or pear-shaped. The large sterile central siphon is eight to nine times as
long and five to six times as broad as each of the small fertile peripheral siphons. Their
mouth is small and exhibits eight radial lappets. The basal part is densely beset with
medusiform gonophores.

Tentacles (figs. 2-4, t). — The corona of tentacles occupies a broad equatorial zone,
nearly half the height of the entire subumbrella. After removal of the tentacles
(fig. 3) this zone appears as a convex elegantly reticulated girdle, the concave inside of
which embraces the inferior half of the campanulate pneumatocyst (fig. 4, p). Each
rhomboidal mesh of the reticulum is the basal insertion of one tentacle. There are
eight to ten transverse rows of tentacles, one alternating with the other, and each row
represents a ring composed of fifty to sixty teDtacles, so that their whole number may be
four hundred to six hundred. The length of the longest (in the middle zone) surpasses
the greatest diameter of the umbrella, whilst the length of those placed in the superior
and inferior rows decreases towards the limits of the tentacular zone. The tentacles are
slender cylindrical filaments, club-shaped at the distal end, and beset with three rows of
cnidospheres (compare above, pp. 38, 39).

Subfamily 2. Porpitellid^e, Haeckel.
Genus 5. Porpitella,1 Haeckel, 1888.

Porpitetta, Hid., System der Siphonophoren, p. 30.

Definition. — Porpitida? with a flat discoidal umbrella, including a circular discoidal
pneumatocyst without marginal lobes. Tentacles numerous, arranged in eight or sixteen
prominent radial bunches.

The genus Porpitella and the following Porpita together make up the subfamily
Porpitellidae, characterised by a discoidal or slightly vaulted umbrella, which includes a
discoidal pneumatocyst, the distal margin of the latter being circular, not divided into
radial lobes. The numerous marginal tentacles in Porpitella are arranged in eight or
sixteen regularly disposed radial bunches, whflst in Porpita they are equally distributed
along the margin of the umbrella.

The new genus Porpitella is founded for those species, formerly placed among
Porpita, which are distinguished by the possession of sixteen radial bunches of marginal

1 Porpitella = Small ring of a buckle, dmiimitive of Porpita.

64 THE VOYAGE OF H.M.S. CHALLENGER.

tentacles. The first species observed was taken by Eschscholtz in the tropical Pacific,
and described in 1829 as Porpita ccerulea.1 It is probably the species of which Huxley
afterwards gave a very accurate anatomical description. Another species of this genus,
also taken in the tropical Pacific (near the Marianne Islands), is Porpita radiata of
Brandt.2 I have been able to compare the excellent (hitherto unpublished) figure and
description left by its discoverer, Mertens. Two specimens of a third species, described
in the following pages, were found by me in the Challenger collection, from Station 244.
It exhibits in several points a remarkable similarity to the interesting deep-sea Medusa,
Pectanthis asteroides.3 I call it therefore after this Trachynemid.

The phylogenetic origin of Porpitella is to be found in Porpalia. It may be
derived from this ancestral form by flattening of the highly vaulted umbrella and the
pneumatocyst, which thus become more or less discoidal.

Porpitella pectanthis, n. sp. (PL XLVL).

Habitat. — Station 244, Northern Pacific, between Japan and Honolulu ; June 28,
1875 ; lat. 35° 22' N., long. 169° 53' E. Surface.

Umbrella (fig. 1, from above; fig. 2, from below; fig. 3, meridional section). — The
disc is a biconvex lens, the horizontal diameter of which amounts to 12 or 15 mm.,
and is three times as great as its vertical axis (4 to 5 mm.). The meridional section
(fig. 3) demonstrates that the larger superior half of the umbrella is occupied by the
discoidal pneumatocyst (p), the smaller inferior half by the lenticular centradenia (uc).

Exumbrella (fig. 1). — The superior or apical face \ of the umbrella is slightly convex,
and exhibits an elegant radial striation, crossed by numerous concentric rings. Sixteen
more prominent ribs bear a number of conical papillse, and between these numerous
more delicate, also denticulate, ribs radiate from the centre. The stigmata open at the
apex of the conical papillse. An elegant pigment-star with sixteen brown rays indicates
the course of the main ribs.

Limbus Umhrellee (figs. 3, 7, um). — The free margin of the umbrella is prominent at
the periphery of the lenticular body, and about one-third or one-fourth as broad as the
length of its radius ; it is circular, divided by sixteen slight incisions into sixteen flat
marginal lobes (fig. 1). Its thickened edge includes a series of marginal glands (fig. 7, us).

Subumbrella (fig. 2). — The inferior or basal face of the umbrella is slightly convex,
and divided into four different parts of nearly equal breadth. The central part is
occupied by the large sterile central siphon ; this is surrounded by three circular
concentric zones ; the first zone is occupied by sixteen smaller sexual siphons (bearing

1 1, p. 179, Taf. 16, fig. 5. 2 25, p. 40.

3 Zool. Cliall. Exp., part xiL p. 20, pis. vii., viii.

EEPOET ON THE SIPHONOPHOE^. 65

clusters of gonophores) ; the second zone is marked by the corona of tentacles, divided
into sixteen bunches ; and the third, outermost, zone is formed by the inferior face of
the free peripheral limb.

Pneumatocyst (fig. 4, superior or apical view; fig. 5, inferior or basal view; figs. 3, 6,
7, p, meridional sections). — The float, filled with gas, is a circular disc, the horizontal
diameter of which (9 to 12 mm.) is ten to twelve times as great as its vertical diameter
(1 to 1"2 mm.). Its thickness is nearly equal throughout, or increases a little towards
the margin. The superior or exumbrellar face (fig. 4) is slightly convex, and exhibits
numerous denticulate radial ribs, sixteen of which are more prominent (fig. 1). Numerous
stigmata (pe) open by the conical papillae of the radial ribs. The inferior or subumbrellar
face (fig. 5) is slightly concave and radially folded, numerous radial furrows (sixteen of
which are deeper) corresponding to the ribs of the upper face. Numerous articulate
tracheae (figs. 5, 6, pt ; fig. 8) arise from conical protuberances of the inferior ribs, which
are prominent between every two radial sulci.

The central chamber of'the pneumatocyst (figs. 3, 6, p>h) opens above by a central apical
stigma (jpo), and is surrounded by a regular corona of eight triangular radial chambers ;
each of these bears a circular stigma (fig. 4, pe) on its upper face (placed in variable
points), whdst from its lower face arise one or two short tracheae. The corona of con-
centric ring-chambers, which surround the girdle of eight radial chambers, is composed of
nine to twelve rings. The height (or vertical diameter) of these rings increases from the
centre towards the periphery, whilst the breadth (or horizontal diameter) decreases (figs.
3, 7, pk). The inner or proximal wall of each ring is concave, the outer or distal wall
convex. The concentric rings communicate one with another by eight radial rows of
apertures (figs. 3, 4, pg), which are placed interradially between the perradial sulci. The
innermost or first ring embraces the octoradial chamber-girdle not only from the distal,
but also completely from the basal side (figs. 3, 6, pk) ; the other concentric rings
embrace one another only from the distal side.

Centradenia (figs. 3, 6, 7, tic). — The large central gland (or the so-called liver) is a
circular biconvex lens, the horizontal diameter of which (6 to 8 mm.) is three to four
times as great as the vertical axis (2 mm.). Its upper surface is in close contact with
the concave lower surface of the pneumatophore, its lower surface with the subumbrella.
Numerous radial ribs of the upper surface fill up the radial sulci of the lower surface of
the pneumatophore. The brown liver vessels are very densely crowded in the upper
half, loosely scattered in the lower half of the pneumatophore. ATI these hepatic canals
unite on the lower surface of the centradenia into descending canals, which pierce the
fulcrum of the subumbrella ; eight of these (forming an inner girdle of openings) open
into the peripheral part of the base of the central siphon ; sixteen others (forming an
outer girdle) open into the sexual siphons (sx). The majority of the canals of the central
gland contains in their epithelium that black pigment which is regarded as " hepatic

(ZOOL. CHAIX. EXP.— PAKT LXXVII. — 1888.) Hhkh 9

66 THE VOYAGE OF H.M.S. CHALLENGER.

granules " ; whilst another part is colourless or more or less filled up with guanin-
crystals ("renal granules"). The uppermost canals (between the pouches of the
pneumatocyst) are colourless.

Central Sijjhon (figs. 1, 2, 3, sa).— The large sterile central polypite has the usual
form of a thick-walled cylindrical or inversely conical tube. Its dilated base occupies
the centre of the subumbrella, and is separated from the centradenia by a thick fulcrum
or supporting lamella, the gastrobasal plate ; it exhibits a peripheral ring of eight openings,
leading into the eight radial main vessels (compare p. 31).

Sexual Siphons (fig. 2, fig. 3, sx).— The sixteen peripheral polypites form a regular
corona around the base of the large central polypite, and are separated by a circular furrow
from the corona of tentacles. They bear numerous gonophores on their thinner basal
part, whilst their spindle-shaped distal part opens by a four-lobed mouth (compare p. 37).

Tentacles (figs. 1-3, t). — The numerous tentacles form a submarginal corona, which
occupies about one-third of the subumbrella. They form six to eight concentric rows,
and exhibit a very different length. Seen from above or below the corona presents
sixteen elegant rays, each of which is composed of an adradial bunch of larger tentacles.
The longest tentacles (in the middle of each radial bunch) surpass the diameter of the
umbrella in the contracted spirit specimens, and may be much longer in the living
animal. The form and structure of the tentacles, with three rows of cnidospheres, is that
which is usual in all Porpitidae (compare pp. 38, 39).

Genus 6. Porpita,1 Lamarck, 1816.

Porpita, Lmk., Hist. nat. anim. s. vert., t. ii. p. 483.

Definition. — Porpitidae with a flat discoidal umbrella, including a circular discoidal
pneumatocyst without marginal lobes. Tentacles very numerous, equally disposed in
several concentric circles, not forming radial bunches.

The genus Porpita possesses the same flat discoidal umbrella, and the same circular,
not radially lobate, pneumatophore, as the preceding genus Porpitella ; but it differs from
the latter in the ecpial distribution of the tentacles along the whole margin of the
umbrella. The tentacles are very numerous, and densely crowded in several parallel
circles (as in Porpema), and they are not grouped into radial lobes.

The genus Porpita, hitherto regarded as the only representative of the famfly
Porpitidae, was founded in 1816 by Lamarck upon the first known species, which Forskal
had observed in the Mediterranean, and described very accurately as Holothuria denu-
data.2 Eschscholtz, the founder of the class Siphonophoras, in 1829 placed Porpita in
his family Velellidae, and gave the following definition :3 — " Corpus orbiculare, supra

1 Porpita = Ring' of a buckle, iripirn. * 11, p. 103, Taf. 26, fig. L 1. 3 1, p. 176, Taf. 16.

REPORT ON THE SIPHONOPHORiE. 67

inerme. Tentacula marginalia trifariam glaudulosa." He described five different species,
Two of these only appertain to the genus Porpita as above defined [Porpita mediter-
ranea and Porpita umbella).

The best and most accurate anatomical descriptions of the genus are those given in
1853 by Kolliker of Porpita mediterranea (4), and in 1881 by Alexander Agassiz of the
North Atlantic Porpita linnmana (57). Closely related to the latter is probably the
tropical Atlantic Porpita umbella of Eschscholtz (1). The collection of the Challenger
contains several specimens of a new species, taken in the Northern Pacific, and figured
in PI. XLV. as Porpita fungia. Three other distinct species seem to be Porpita liitkeana
(25), from the Indian Ocean ; Porpita pacifica of Lesson (22) ; and a new southern form,
Porpita australis.

The phylogenetic origin of Porpita is to be found in the preceding genus, Porpitella,
from which it is derived by multiplication and equalisation of the tentacles, not forming
separated radial bunches.

Porpita fungia, n. sp. (PI. XLV.).

Habitat. — Stations 253 to 255, Northern Pacific, between Japan and Honolulu;
14th to 19th July 1855; lat. 38° 9' N. to 32° 28' N, long. 15G° 25' W. to 154° 33'
W. Surface.

Umbrella (fig. 1, meridional vertical section). — The disc is flat, circular, of equal
thickness throughout nearly its whole extent, like a coin. Its diameter is usually 20 to
25 mm., but amounts in the largest specimens to 30 mm. ; its thickness (without the
siphon and tentacles) is 4 to 6 mm. A meridional section (fig. 1) demonstrates that
three-fourths of the thickness belong to the centradenia, one-fourth to the pneumatocyst.

Exumbrella (fig. 2). — -The superior or apical face of the umbrella is flat or slightly
convex, a little depressed in the centre. It is covered with numerous, irregularly scat-
tered, conical tubercles, arising from the upper face of the pneumatocyst. Their number
and size increase towards the centre. The peripheral half of the exumbrella is pierced
by numerous irregularly scattered stigmata (pe). The regular octoradial striation and
the numerous concentric rings, which shine through the silvery exumbrella, are due to the
structure of the subjacent pneumatocyst. An elegant network of anastomosing canals,
with narrow irregular polygonal meshes, is expanded everywhere in the exumbrella.

Limbus Umbrellss. — The free membranous border or limbus of the umbrella overlaps
the tentacular zone to the extent of 1 to 2 mm. It is flatly expanded or reflected
upwards, and includes a series of marginal glands of the usual form (compare above).
The numerous canal-branches of the exumbrella anastomose richly, form an irregular
network, and unite in a circular canal inside the glandular corona ; and from this arise
the vessels of the centradenia and the subumbrella.

68 THE VOYAGE OF H.M.S. CHALLENGER.

SubumbrcUa (fig. 1). — The inferior, distal or basal face of the umbrella is divided into
four different zones. The central zone, with a diameter of 3 to 4 mm., is occupied by
the gastrobasis or the fundus of the large central siphon. The broad middle or gonostylar
zone (4 to 6 mm. in breadth) is occupied by the numerous sexual siphons or gonostyles.
The third or tentacular zone (2 to 3 mm. broad) bears the numerous tentacles. The
fourth or outermost zone (1 to 2 mm. broad) is formed by the inferior face of the free
mantle-border.

Pneumatocyst (fig. 1, fig. 5, pf). — The float, filled with air, is a flat circular disc of 15
to 20 mm. diameter. Its thickness increases considerably from the centre towards the
margin, owing to the height of numerous radial folds. The form of the pneumatocyst
presents a great resemblance to a regular Fungia, the disc being folded radially in a very
regular manner. The vertical folds arise in the upper surface in eighty or ninety high
radial ridges, with deep valleys between them, whilst branched radial lamellae are pro-
minent on the lower face.

The octoradial structure of the pneumatocyst is very distinct on its upper face, since
the eight equidistant primary rays are more prominent than all the others. They arise
from the septa of the eight radial chambers which surround the central chamber. The
octant between every two primary folds is bisected by a secondary ray, somewhat less
prominent, but also stronger than all the others. Sixteen tertiary or adradial ridges
arise in the middle between the eight primary and the eight secondary rays. The other
rays are developed in the peripheral half of the disc only. The total number of radial
ribs is about eighty in a specimen of 1 5 mm. diameter, one hundred and twenty in a larger
specimen of 20 mm. The most elevated part of each radial rib bears a radial series of
stigmata. The number of concentric annular septa is about fifty in the former, eighty in
the latter. These are wider (about twice as broad) in the middle part of the disc than in
the central and the peripheral part.

The thickness of the chitinous wall of the air-chambers is much greater in the upper
than in the lower face, and it increases from the periphery of the disc towards the centre.
It equals in the central half of the disc the height of the air-chambers. Numerous strata
of chitinous substance are here deposited as secondary supports of the disc-wall, and have
closed the stigmata (fig. 1 , p2). The conical tubercles of the surface of the disc are pro-
duced by stronger deposits at separate places (p1). The stigmata of the air-chambers
remain open in the peripheral part of the disc only (_pe); they are urn-shaped, very
numerous, and irregularly scattered in radial rows (fig. 2, pe).

The lower face of the pneumatocyst, which is in close contact with the centradenia, is
more strongly folded than the upper face ; the folds are here ramified centrifugally, and
form high triangular lamellae, the height and number of which increase from the centre
towards the periphery (fig. 1, £>4). Eight primary radial lamellae, arising from the septa
of the eight pericentral radial chambers, are more prominent than the eight secondary

REPORT ON THE SIPHONOPHOR^. 69

alternating, and these more than all the other lamellae. The centrifugal dichotomous
ramification of the lamellae increases gradually towards the periphery, and new peripheral
folds are interposed between the centrifugal folds, so that their number at the margin
of the disc is much greater than that of the simple radial ridges of the upper surface.
The crest of the folds is elegantly denticulate, and from it arise two opposite radial rows
of tracheae. The tracheae or aeriferous tubules in this Porpita are exceedingly numerous,
amounting to many thousands. The majority of them are short and end half way up the
centradenia. A smaller number pierce the latter and the subjacent support, and project
into the exodermal wall of the central siphon and the surrounding gonostyles. They
terminate here in the basal half of the latter, inside the exodermal epithelium (fig. 8, £>£).

The circular concentric ring-chambers of the pneumatocyst communicate one with
another by radial apertures or " pneumothyras," oblique elliptical openings, which are
placed in the radial sulci between the folds of the lower face.

The central chamber possesses, as usual, a central stigma in its upper face, as does also
each of the surrounding eight radial chambers. From the basal part of each of the latter
arises a bunch of three or four short tracheae. In the basal sulci between these are eight
openings, which lead into the first ring-chamber.

Centradenia (fig. 1, uh, meridional section; fig. 3, inferior face; figs. 6-8, un, parts
of sections). — The large central gland (or the so-called "liver") is a biconvex lenticular
disc, the horizontal diameter of which is four times as great as its vertical axis ; the latter
measures in a specimen of .20 mm. diameter (umbrella) 3 mm., the former 12 mm. Its
superior face has a regular radiate appearance ; innumerable radial folds (thirty-two of
which are stronger) fitting into the radial grooves which lie between the lamellar pouches
of the inferior face of the pneumatocyst. The height of these folds increases from the
centre towards the periphery. The circular margin meets the line which marks the
boundary between the gonostylar and tentacular zones.

The inferior face of the centradenia is less convex than the superior, and is divided
into a white central disc (kidney) and a peripheral brown radiate zone (liver). The
former covers the roof of the central siphon (sa), and surrounds it like a broad, white
girdle (fig. 3, un) ; the peripheral part of the brown liver (fig. 3, sh) surrounds again the
former as a dark radiate ring. The gonostyles arise as well from the former as from the
latter.

The meridional or vertical section of the centradenia (fig. 1) demonstrates that its
solid exodermal parenchyma is traversed by a dense network of innumerable canals, the
greater part of which are darkly coloured by a brown (hepatic) pigment. This is want-
ing in a part of the superficial canals, and in the inferior white central disc (" kidney"),
which contains masses of guanin-crystals. Innumerable tracheae terminate between
the canal branches ; their distal openings being surrounded by (air-secreting ?) exoderm
cells (compare the explanation of figs. 6-8).

70 THE VOYAGE OF H.M.S. CHALLENGER.

Central Siphon (fig. 1, sm, fig. 4). — The large sterile central polypite is inversely
conical, in the contracted state about as long as the diameter of its broad base, which is
a quarter or a fifth of the diameter of the umbrella. Its thick muscular wall exhibits
sixteen longitudinal folds, and between these run sixteen deep grooves, which open at the
bottom of the stomach into the sixteen radial main canals. The distal mouth of the
central siphon is octolobate. Its opposite proximal roof is separated by a strong fulcrum
or supporting lamella, the gastrobasal plate (fig. 1, st), from the superjacent kidney.

The sixteen radial main canals, which arise from the periphery of the base of the
stomach, run along the subumbrella towards the peripheral edge of the limb, where they
are united in a circular marginal canal. They give off innummerable branches ; of these
the ascending ones enter into the centradenia, the descending partly into the gonostyles,
partly into the tentacles. Numerous superficial mantle- vessels arise from the marginal
canal and enter centripetally into the exumbrella, where they form an irregular dense
network above the pneumatocyst.

Sexual Si£)hons (figs. 1,8, sx). — The gonostyles cover the greatest part of the sub-
umbrella, and are densely crowded in the broad zone which lies between the central siphon
and the tentacular zone. Their number amounts to several hundreds. They are covered
with bunches of gonophores in the cylindrical proximal half, with patches of cnidocysts in
the spindle-shaped distal half. Their distal mouth is often divided into four or eight
small lobes.

Tentacles (fig. 1, t). — The tentacular zone of the subumbrella, inside the free pro-
minent limb, is about as broad as the base of the central siphon. It presents an elegant
reticulum, with rhomboidal meshes, when the tentacles are removed ; each mesh being
the base of a detached tentacle. These are arranged in six to eight concentric rows. In
the largest specimens their number exceeds one thousand. Their length may exceed the
diameter of the umbrella ; the majority, however, are mueh shorter. The structure of the
club-shaped tentacles is the usual one, with three rows of stalked cnidospheres (compare
p. 39).

Family III. Velellid,e, Eschscholtz, 1 829.

VeleUidx, Eschscholtz, System der Aealephen, p. 165 (sensu restricto).

Definition. — Disconectse with an elliptical or amphithect, often nearly quadrangular
umbrella, including a polythalamous pneumatocyst of the same form, which is composed
of numerous concentric rings, and usually bears in its diagonal a vertical crest. Always
a membranous vertical sail upon the umbrella. Marginal tentacles simple, without cnido-
spheres. Central siphon surrounded by numerous peripheral fertile siphons, which bear
the gonophores.

The family Velellidae, founded by Eschscholtz in 1829, comprised originally all Dis-

REPORT ON THE SIPHONOPHOR.E. 71

conectaa, or all the " Medusas chondrophorse " of Chamisso and Eyssenhardt. After-
wards (in 1835) Brandt separated the true Velellidaj (with elliptical disc and vertical
crest) from the Porpitidse (with circular disc, without crest). The Velellidae, thus
restricted, agree with the Porpitidse in the polygastric structure, not only the large
sterile central siphon possessing an open mouth at its distal end, but also each of the
surrounding gonostyles. These peripheral polypites, which bear the gonophores budding
from then proximal part, are therefore not mouthless palpons (as in the Discalidse), but
mouth-bearing, feeding, and digesting secondary siphons. On the other hand, the Velellidse
differ from the Porpitidse (as well as from the Discalidse) in the peculiar amphithect or
bilaterally-radial ground-form of the body, produced by the prolongation of the sagittal
axis, and shortening of the frontal axis ; and, further, in the development of a peculiar
vertical crest or sail, which arises from the exumbrella either in the sagittal or in a
diagonal axis.

Eschscholtz, in his fundamental work,1 divided his Velellidae into three genera : —
Rataria, Velella, and Porpita. The genus Rataria, however, was considered by the ma-
jority of subsequent observers to consist only of young forms of Velella. A new species of
Rataria, found in the Challenger collection, proved to be an autonomous genus, provided
with gonophores. Although the different Ratarize, described by some authors, may be
merely young Velellse, there nevertheless exist also Velellidae which become mature in
the permanent Rataria-fovm. The numerous species of the true Velella were disposed
in my System (p. 31) in two genera : — Velella (sensu restricto), with an ebiptical
umbrella and simple corona of tentacles ; and Velaria, with quadrangular umbrella and
double or multiple corona of tentacles. For this latter the old name Armenista (or
Armenistarium of Carburius, 1757) may be better retained.

Umbrella. — The common trunk of the cormus, which corresponds to the umbrella of
a hydromedusoid person, is in all Velellidse a flat, horizontally expanded, and floating
disc, distinguished from the circular disc of the Porpitidse and DiscaUdae, firstly, by
its bflateral form, and secondly, by tke vertical crest or sad. Tke latter is originally
notking more tkan a simple longitudinal fold of tke exumbrella, and may be regarded
as tke primary cause of tke peculiar fundamental form. Tke tkree genera wkick we
kave distinguisked represent tkree different degrees or historical steps in its peculiar
development : — Rataria, next to tke ancestral group Porpitidse, kas an elliptical disc, and
tke sail placed in its sagittal plane, in tke longer axis ; in Velella the sad turns a little
around the vertical main axis, and comes to be situated in a diagonal axis of the disc ;
finally, in Armenista the disc becomes quadrangular or parallelogram-shaped. Besides,
a vertical crest of the pneumatocyst, as a support of the soft sail, is developed in the two
latter genera, but is wanting in Rataria.

Amphithect Fundamental Form. — The peculiar fundamental form presented by the

1 1, 1829, p. 1G6.

72 THE VOYAGE OF H.M.S. CHALLENGER.

umbrella of the Velellidse may be called either amphithect or bilaterally-radial. It is
characterised by three unequal dimensive axes, each perpendicular to the other two ; one
being allopolar (with unequal poles), the other two isopolar (with equal poles). The allo-
polar axis is the vertical main axis, its upper or apical pole determined by the top of the
sail, its lower or basal pole by the mouth of the central siphon. The greater isopolar axis
is the sagittal axis of the disc (the major axis of the ellipse), which divides it into two equal
symmetrical halves, right and left. The smaller isopolar axis is the transverse or frontal,
which is perpendicular to the latter, and separates the disc also into two equal halves,
dorsal and ventral ; it corresponds to the minor axis of the ellipse.

The octoradial character of their amphithect ground-form is always indicated by the
origin and course of the eight primary gastro-canals, which arise from the base of the
central siphon ; secondly, it is marked by the centre of the pneumatophore, which
exhibits more or less distinctly eight radial chambers around the simple central chamber ;
thirdly, it is often indicated by the radial arrangement of eight primary marginal
tentacles and of other parts. The umbrella of the Velellidse is therefore composed originally
of eight equal parameres (or homotypical radial parts), like that of the Porpitidse and
Discalidse ; but it differs from that of the latter in the fact that the parameres are dis-
posed in pairs, so that the disc may be regarded also as composed of four paired quadrants ;
and sometimes the limits of these are sharply marked off by four marginal incisions of
the pneumatophorous disc.

The quadriradial appearance, the body seeming to be composed of four parameres (as
in the most Medusa?), is mainly obvious in the more highly developed Velellidse. But
regarding their phylogenetic origin from the Porpitidse, we must assume that this funda-
mental form has arisen from a true octoradial type composed of eight parameres. In no
case can we regard this fundamental form as uniradial, a point of view which is repre-
sented by Chun.1 I agree perfectly with the explanation of the origin of the sail which
Chun there gives (loc. cit., p. 15) ; but I cannot agree with his promorphological
deductions. I cannot concede at all that uniradial fundamental forms exist anywhere.

A trice asymmetry, mentioned by many authors in the umbrella of the Velellidse,
does not exist ; for in every case the two halves of the body, which are separated by any
possible meridional section (through the vertical main axis), are perfectly equal ; and the
dorsal and ventral halves cannot be distinguished by any character ; the right and left
halves being likewise equal one to another. The so-called "asymmetry" in the disc of
many Velellidse is only the beginning of a spiral twisting, caused by a slight dislocation
of the vertical sail, turning more or less around the vertical main axis. But in the
elliptical Rataria (and also in the similar Ratarula-larvse of Velella and Armenista) the
sail is placed in the sagittal plane, and its later dislocation from this plane is a secondary
alteration, comparable to the turning of the sail in a boat sailing before the wind.

1 Chun, Fauna and Flora des Golfes von Neapel, i., Ctenophoren, 1880, p. 14.

REPORT ON THE SIPHONOPHOR^E. 73

This sail, or the vertical crest of the Velellidse, is the most characteristic part of their
trunk, and its gradual development is the primary cause of their peculiar amphithect
form. The sail is originally nothing other than a small fold of the exumbrella, or the soft
upper lamella of the disc. We may assume that the elevation of such a fold in any
ancestral Porpitidse was very useful as an aid to the locomotion of the pelagic animal
floating on the level of the sea by its horizontal disc. Natural selection, therefore, will
have increased the height of that crest, driven by the wind, and the immediate effect
must have been the transformation of the circular disc into an elliptical one, the sail
occupying the major axis of the ellipse (Rataria). Afterwards the soft and contractile
sail becomes supported by the development of an inner chitinous crest, arising from the
pneumatophore ( Velella), and finally the whole outline of the disc, and the arrangement
of its marginal parts, assumes the form of a parallelogram, and the sail is placed in its
diagonal axis (Armenista). A continuous series of intermediate transitional forms
conducts us from the elliptical Rataria (with sagittal sail), through different forms of
Velella, to the most specialised parallelogram-shaped Armenista (with diagonal veil).
The special form of the sail in the two latter genera depends upon that of the supporting
firm crest of the pneumatophore ; in Rataria, however, where the skeleton-crest is
wanting, its form differs greatly according to its varying state of contraction.

Exumbrella. — That part of the trunk which includes the pneumatocyst, and cor-
responds to the invaginated exumbrella, is composed in the Velellidse, as in the other
Disconectge, of two parallel membranes connected by branched septa. The outer mem-
brane, or the permanent exumbrella (the uninvaginated part), is the pneumatocodon ; its
exodermal epithelium is armed with many cnidoblasts, and beyond it is placed a strong
muscular plate, composed of longitudinal or radial fibres. The inner membrane, or the
invaginated part of the exumbrella, is the pneumatosaccus ; its thinner exodermal
epithelium envelops like a complete sac the whole surface of the pneumatocyst, and
this is nothing more than the hardened chitinous cuticula secreted by the former. A
great number of septa connect both membranes, and between them occur the canals of
the exumbrella, more radially in the horizontal surface of the disc, more longitudinally
and parallel in the vertical surface of the sail (on both sides of it). These pallia! canals
open in the periphery of the horizontal disc into the marginal canal, and along the free
margin of the sail into a crescentic canal, running along the whole margin.

Pneumatocyst. — The chitinous polythalamous float filled with air, which we call pneu-
matocyst (usually called the " inner shell "), always assumes the form of its surrounding
matrix, the pneumatosaccus. It is, therefore, in the Velellidaa elliptical or cmadrangular,
and very different from that of the Porpitidae and Discalidse, where it is always circular
and regularly octoradial. Since, however, the former have arisen originally from the
latter, their pneumatocyst also must be regarded as an amphithect or bilateral modifica-
tion of that circular float of the latter. Indeed, in all Velellidae there are traces, more or

(ZOOL. CHALL. ESP. — PART LXXVIJ. — 1888.) Hhhll 10

74 THE VOYAGE OF H.M.S. CHALLENGER.

less distinct, of the same octoradial composition of the centre of the float, which is
immediately evident in all Porpitidse and Discalidse.

The pneumatocyst of Rataria consists only of a horizontal, slightly campanulate or
flatly conical disc of elliptical outline, whilst that of Velella and of Armenista bears a
solid vertical triangular crest, placed in a diagonal axis of the disc.

The pneumatocyst of Rataria is of the highest interest, since it offers all desirable
intermediate forms between the bilateral crested float of the other Velellidaj and the
circular crestless float of the Porpitidse. This is the more important, as the young
Ratarula-larvse of Velella and Armenista exhibit the same structure of the pneumatocyst
(during a longer or shorter time) which is permanent in the autonomous genus Rataria.
A central chamber, placed in the centre of the exumbrella, is here always surrounded by
eight radial chambers, just as in the Porpitidae and Discalidse. But whilst in these two
families each radial chamber (as well as the central chamber) possesses a stigma, or a free
opening on its upper surface, there are in the similar pneumatocyst of Rataria three
such openings only, one in the upper face of the central chamber and one on each side of
it, in the two chambers, which are directed towards the two sagittal poles, or the poles of
the major axis of the ellipse. The stigmata of the six other chambers seem to be lost by
phylogenetic reduction (PI. XLIV. fig. 8). Each of the eight radial chambers usually
possesses a trachea or a bunch of descending air-tubules on its lower face (fig. 9).

The octoradial structure of the pneumatocyst, which is obvious in Rataria, is also
recognisable in the similar Ratarula-larvse of Velella and Armenista. But it is not
ecmally distinct and well preserved in all species of these two genera. The peripheral
wall of the central chamber, which separates it from the eight surrounding radial
chambers, is pierced by eight openings, connecting the former with the latter. These
openings of communication afterwards often become so enlarged that the eight chambers
appear only as radial lobes of the central chamber, and sometimes the eight radial septa
between the former are so reduced that the eight lobes nearly disappear. This fact
explains the striking contradictions of the former observers, some of whom interpret the
Ratarula-larvse as young forms of Velellidse (Huxley, Bedot, &c), some as larvae of
Porpitidse (Agassiz, Burmeister, &C.).1 Indeed all these larvse belong to the Velellidse,
since the larvae of the Porpitidse never develop a vertical sail. But the octoradial struc-
ture of the central part of the pneumatocyst, which is always very distinct in the latter,
is of very variable distinctness in the former ; sometimes it is well preserved, at other
times not, and sometimes the cenogenetic modification is so strong that it becomes quite
lost.

The concentric ring-chambers of the pneumatocyst, which surround its octoradial
central part, are not circular in the Velellidse (as in the Porpitidse and Discalidse), but
more or less elliptical, with prolonged sagittal axis, and shortened transverse or frontal

1 Compare Pagensteclier, 55.

REPORT ON THE SIPHONOPHORiE. 75

axis. The ellipses are short and nearly circular in the young Rataria; they become
longer and sometimes slightly quadrangular in Velella, and completely parallelogram-
shaped in Armenista. The number of these concentric ring-chambers is very variable in
the different species, two to eight only in the smallest species (Rataria), twenty to
thirty or more in the larger (Velella), and fifty to eighty or more in the largest forms
(Armenista).

Pneumothyrse. — The concentric ring-chambers of the pneumatocyst are all in open
communication one with another. Each annular elliptical septum between two chambers
is pierced by two opposite openings or septal pores, one in the dorsal half, the other in
the ventral half of the disc. All these septal pores are placed in a straight line, cutting
the major axis of the disc at a very small angle, as was first shown by Kolliker.1 There
are, therefore, not eight radial rows of pneumothyrae as in the ancestral Porpitidae, but
only two opposite radial rows. In some species of Velellidse, however, there seem to
exist two other opposite rows, placed in a transverse line near the frontal groove.

Stigmata. — All Velellidae possess a relatively small number of superficial openings on
the ring-chambers, which lie at their apical or superior surface, and serve for the emission
of gas. The number of these stigmata is much smaller than in the Porpitidae. Usually
only every third or fourth ring possesses a pair of opposite stigmata ; sometimes rings
with and without stigmata alternate regularly ; rarely each ring possesses one pair. All
the gas-pores or stigmata discovered by Kolliker lie in a straight line, just as do the
septal pores, and the line of the former is placed between the line of the latter and the
base of the vertical crest. Half the stigmata, therefore, lie in the ventral half of the disc
on the right side of the crest, and the other half in the dorsal half on the left side, or
vice versa (compare PL XLIII. fig. 5, pe). The direction of the series of stigmata in all
Velellidae is already marked by the three first stigmata of their Ratarula-larvae. These,
as well as the mature Rataria (PI. XLIV. fig. 8), possess only three stigmata, which are
placed in a line, cutting the sagittal axis of the horizontal disc at an acute angle ; one of
the three pores lies near the centre (j)o) ; the second on the left (pe), and the third on
the right side. All the following stigmata develop in the direction of that line. In many
Velellidae the stigmata lie so near the crest-basis that they are difficult to find.

Tracheae. — The number of tracheae arising from the lower face of the pneumatocyst
in the Velellidae is also much smaller than in the Porpitidae, but they are longer than in
the latter and usually branched. In many species eight tracheae arise from the periphery
of the eight radial chambers which surround the central chamber ; these are usually
branched (PI. XLIII. fig. 6 ; PI. XLIV. fig. 9). A small and variable number of other
tracheae arise here and there, irregularly scattered, from other parts of the pneumatocyst.

The vertical crest of the pneumatocyst, or the sail-skeleton, wanting in Rataria,
exhibits different degrees of development in the various species of Velella and Armenista.

1 Kolliker, 4, Tat xi. fig. 11.

76 THE VOYAGE OF H.M.S. CHALLENGER.

At first it is a low thin crest in the base of the soft muscular sail, and afterwards arises
as a hioh vertical lamella, usually of more or less triangular form ; the top of the triangle
is the highest point of the body, and placed in the upper or apical pole of the vertical
main axis. The broad base of the triangle, placed in one diagonal Hue of the parallelo-
gram-shaped disc,' is usually about one and a half times as long as each of the two equal
lateral sides. The substance of the crest is a thin chitinous plate, secreted from that part
of the pneumatosaccus which arises from the diagonal of the disc as a vertical fold. It is
perfectly homogeneous, solid, and structureless, and contains no canals nor air-chambers.
A number of lines or thin ridges, parallel to the two ascending edges of the triangular
crest, and visible on both flat sides of it, indicate its successive growth.

Central Siphon. — The large central polypite of the Velellidae differs from that of the
Porpitidse and Discalidse in its bilateral compression ; the transverse section of its basal
part is circular in the two latter families, elliptical in the former ; the major axis of the
ellipse corresponds to that of the umbrella. Its general structure and shape are other-
wise the same as in the other Disconectse. The central siphon is comparatively large in
the small Rataria, where the number and size of the peripheral siphons is small, whereas
in the larger species of Velella and Armenista, where the peripheral siphons are very
numerous, the central polypite is less preponderant. The thick wall of the central
siphon is very contractile, and composed of two strong muscle-plates, an outer longi-
tudinal and an inner circular, both separated by a strong elastic fulcrum. The wall often
exhibits prominent radial or longitudinal folds, eight in the smaller, sixteen or more in
the larger forms. Correspondingly, the terminal mouth is often four-lobed or eight-lobed
(PI. XLIII. figs. 4, 8, so ; PI. XLIV. figs. 2-5, so).

Centradenia. — The large central gland, or the so-called " central organ " (formerly
" liver"), exhibits the peculiar composition described above (p. 31). Bedot has given
an accurate histological description of its structure (59, 60). In the Velellidse it is more
developed than in the Discalidse, but much less than in the Porpitidse. It does not
usually occupy the greater part of the superior face of the subumbrella as in the latter,
but only its central part, between the centre of the float above and the base of the large
central siphon below. The outline and the horizontal section of the centradenia are not
circular, as in the Porpitidse and Discalidse, but elliptical or lanceolate, the major axis
of the ellipse corresponding to that of the umbrella. Its superior or apical face is more
or less conical, and fills up the concave inferior face of the pneumatocyst. Its inferior or
basal face is even, separated by the gastrobasal plate from the base of the central siphon.
The difference between the hepatic vessels in the superior half of the central gland, and
the renal vessels in its inferior half, seems to be usually not so striking in the Velellidse
as in the Porpitidse. The canal-plexus, as well as the compact parenchyma of exoderm
cells, which fills up the interstices of the canal-network, and probably secretes the gas,
is in the former far less developed than in the latter. This weaker development of the

REPORT ON THE SIPHONOPHOR^E. 77

centradenia in the Velellidae is probably due to their pelagic habit of life, and the
development of the vertical sail as an excellent means of passive locomotion. The
Porpitidas, on the other hand, are probably inhabitants of different depths, and only
occasionally come to the surface ; their hydrostatic apparatus and the gas-secreting gland
are therefore more developed.

Gonostyles. — The numerous polypites of the . subumbrella, which produce by budding
the medusiform gonophores, are in the Velellida± mouth-bearing siphons, as in the
Porpitidae, not mouthless palpons as in the Discalidae. They are, therefore, usually
called "smaller polypes," " sexual polypites," or "peripheral siphons" (shortly "peri-
siphons "). They occupy usually, densely crowded in great numbers, a broad gono-
stylar zone, and often the whole space of the subumbrella between the central
siphon and the submarginal corona of tentacles. But at first their number seems to be
restricted to eight or sixteen ; at least this is the case in Rataria cristata (PI. XLIV.
fig. 2), and also in some similar young larvae (Ratarula) of Velella. Their form and
structure are the same as in the Porpitidse, already described above (p. 36).

Tentacles. — The corona of submarginal tentacles is in the Velellidas far less developed
than in the Porpitidae ; their structure, too, is simpler than in the latter. The corona is
simple, composed of a single series of filaments in Rataria and Velella ; it is double or
multiple, and composed of two or three (seldom more) series in Armenista. Their
number is probably originally eight, and this occurs in some Ratarula-larvaa ; but there
are other similar larvae in which the corona bears a variable number of tentacles irregu-
larly disposed. Some very small and young larvae of the Ratarula-form exhibit only
two tentacles, at opposite poles of the major axis of the ellipse, and corresponding to
the two primary stigmata of the pneumatocyst.1 The only Rataria which 1 have
observed in the adult state (with gonophores) possessed sixteen tentacles, rather regu-
larly disposed along the limb (PI. XLIV. figs. 1, 2). In Velella this number is soon
increased, and amounts in the simple series usually to fifty to eighty, often more than a
hundred. In A rmenista there are usually some huudreds, or sometimes thousands ; the
smaller tentacles of the outer (or distal) series alternating with larger filaments of the
inner (or proximal) series.

Form of the Tentacles. — The general structure of the tentacles in the Velellidae is the
same as in the Porpitidae, but their form is much simpler, and the three rows of stalked
cnidospheres, which are characteristic of the tentacles of the latter famdy, are wanting.
The submarginal filaments of all Velellidae are simple cylindrical tubes, sometimes
slightly compressed, usually gradually tapering towards the rounded distal end, seldom
somewhat club-shaped ; in very young larvae they are conical and pointed. Their arma-
ture with cnidoblasts is very different from that of the two other families. Usually each
tentacle bears only two lateral ribands of cnidoblasts, sometimes four (two stronger

1 Compare Bedot, 60, 1884.

78 THE VOYAGE OF H.M.S. CHALLENGER.

lateral and two weaker medial, an upper and a lower). The cnidoblasts are often more
crowded towards the distal end. Sometimes they are irregularly scattered.

Ontogeny. — The larvse of the Velellidse were described by Eschscholtz,1 who founded
upon them the new genus Rataria. We retain here this genus for those simplest
forms of the family, which, at this same stage, develop a corona of sexual siphons around
the central siphon, and gonophores from the gastral walls of these gonostyles. The
larval forms of Velella, described usually as Rataria, lack the gonostyles, and are better
designated as Ratarula. Pagenstecher (55) has given a careful historical and anatomical
description of these larval forms. But I suppose that the numerous larvae examined by
him, and all figured as Rataria, may be mixed larvae of Velella and Porpita. The
regular octoradial pneumatocyst, figured in his Taf. xli. fig. 1 , seems to belong to Porpita,
since the same organ in Velella is always more or less amphithect or bilateral. . But no
larva of Porpita has the vertical sail or crest shown in his figs. 3-5, &c. ; these belong
to Velella.

The medusiform gonophores, which bud in clusters from the gonostyles of the
Velellidse, and afterwards become detached (Discomitra, Chrysomitra), are described by
many authors (mainly by Kolliker, 4, Vogt, 5, Gegenbaur, 7, Leuckart, 8, Huxley, 9, Alex-
ander Agassiz, 57, and others (compare on the metagenesis of the Velellidse, p. 39 above).

Phylogeny. — The Velellidse have probably descended from the elder forms of
Porpitidse (or directly from the Discalidse) ; their peculiar amphithect or bilateral develop-
ment is due to the production of the vertical sail as a longitudinal fold of the
exumbrella.

Synopsis of the Genera of Velellidse.

1. Umbrella elliptical, with integral margin. Pneumatocyst without crest. Corona of

tentacles simple, ......... 7. Rataria.

2. Umbrella elliptical or quadrangular, with integral margin. Pneumatocyst with a crest.

Corona of tentacles simple, . . . . . .8. Velella.

3. Umbrella quadrangular, with a lobate margin. Pneumatocyst with a crest. Corona of

tentacles double or multiple, ....... 9. Armenista.

Genus 7. Rataria? Eschscholtz, 1829.
Rataria, Esch., System der Acalephen, p. 166.
Definition. — Velellidse with an elliptical umbrella and a vertical membranous sail
placed in the major axis of the ellipse. Margin of the umbrella not lobate. Pneumato-
cyst flatly campanulate or more discoidal, elliptical, without vertical chitinous crest.
Submarginal corona of tentacles simple.

The genus Rataria is the simplest and most primitive form of the Velellidse, and

1 1, p. 166. 2 i?atoria= A float.

EEPORT ON THE SIPHONOPHORJE. 79

comprises those small forms of the family, the vertical sail of which contains no chitinous
crest. The pneumatocyst, therefore, is the horizontal elliptical chitinous disc alone ; no
vertical skeleton crest is developed upon its surface, as in Velella and Armenista. The
soft vertical sail is placed in the major axis of the ellipse, not obliquely in a diagonal.
The species of Rataria upon which Eschscholtz founded the genus were probably young
larval Velellse, perhaps the same as those of which Bedot has during the last few years
given an anatomical description (58-62). Pagenstecher gave in 1863 a very accurate
description of Rataria, with historical remarks on the Velellidse in general, and discussed
the question whether these forms of Disconectse were only a larval stage of Velella (or
perhaps of Porpita) or an independent peculiar genus of this group. As a fact both
alternatives are true. Rataria cristata, from the Tropical Atlantic, described in the
following pages, and found in the Challenger collection (Station 348), is a VelelHd which
produces gonophores in the form of Rataria, and therefore is the representative of an
independent genus. The larvse of Velella and Armenista, on the other hand, all pass
through a larval stage similar to the former. But no Porpitidse have a similar larval
form, since the vertical sail is completely wanting in this family, and is only to be found
in the family Velellidse. Regarded from a phylogenetic point of view, Rataria is a
necessary intermediate link between the older Porpita and the more modern Velella.

Rataria cristata, n. sp. (PL XLIV.).

Habitat.— Station 348, Tropical Atlantic ; April 9, 1876 ; lat. 3° 10' N., long. 14° 51'
W. Surface.

Umbrella (fig. 1, from above ; fig. 2, from below ; fig. 3, half lateral, half apical view;
fig. 4, lateral view ; fig. 5, frontal section). — The horizontal disc of the umbrella is elliptical,
4 mm. long and 3 mm. broad in the expanded state. The vertical sail which arises in
its sagittal or longitudinal axis, is very contractile, and therefore exhibits very different
forms (figs. 3, 4). The vertical transverse section of the umbrella (fig. 5) demonstrates
that the greatest part of its volume is occupied by the pneumatocyst (.])/), and the
centradenia (uc) which lies between this and the central siphon (sa).

Exumbrella (figs. 1, 3, 4). — The superior or apical face of the umbrella is divided
into three parts — the vertical sail (velarium), the campanulate part, which includes the
pneumatocyst (pneumatophore), and the broad horizontal free border (limbus).

Limhus Umbrellm (uu). — The peripheral border of the horizontal disc, which surrounds
the campanulate pneumatosaccus, is an elliptical ring of 0'5 mm. in breadth ; its outer
edge is densely beset with a series of marginal muciparous glands (us), and on the inside
of this glandular corona runs the elliptical marginal canal (fig. 10, cc), into which open
the numerous radial canals of the umbrella (ce).

80 THE VOYAGE OF H.M.S. CHALLENGER.

Velarium (figs. 3-5, uf). — The vertical sail is a simple fold of the exumbrella, which
arises in the longitudinal or sagittal axis of the elliptical disc, along the median line of
the campanulate pneumatosaccus. Its form and size are very variable, since it is very
contractile ; if highly expanded, it appears nearly rectangular, with a median notch at
the central top (fig. 3), and its vertical diameter is greater than the major axis of the
horizontal disc ; if strongly contracted it appears much smaller, and has the form of a
shallow vertical elliptical disc (fig. 4). At other times it is more crescentic in form, or
cordate with a deep constriction in the middle of the top.

The velarium is composed of an elastic support, or a thin vertical plate of jelly in its
median plane (fig. 5), and a thin mantle-plate of the exumbrella, covering both sides of
this fulcrum. This mantle-plate exhibits beyond the exodermal epithelium a double
strong muscular layer, composed of two different strata, an outer thinner layer of trans-
verse or horizontal muscles, and an inner thicker layer of longitudinal or vertical
muscles ; the bundles of the latter are parallel, of equal breadth, about forty or fifty on
each side.

The parallel vertical bands of equal breadth ascending in the velarium to its top
(twenty to thirty in the sagittal diameter) are simple vessels, which arise from the ex-
umbrella of the campanulate pneumatosaccus. They are united at the free superior edge
of the sail by a marginal sail canal. This runs along the whole free edge of the sail and
opens at its base into the two sagittal canals of the exumbrella, which run to the two
opposite poles of its major axis.

Subumbrella (fig. 2). — The inferior or basal face of the umbrella, beyond the series of
marginal glands, consists from without, inwards, of the following parts : — (l) The inferior
or subumbral side of the broad mantle border (urn) ; (2) the elliptical corona of tentacles
(t) ; (3) the corona of gonostyles (gs) ; and (4) the large central siphon (so).

Pneumatocyst (fig. 8, from above; fig. 9, from below; fig. 3,pf, in profile; fig. 5,^/*, in
vertical section). — The chitinous thin-walled float, filled with gas, is flatly campanulate
with an elliptical quadrilobate outline. Its length (or principal axis) is 2 mm., its
breadth or transverse axis 1*5 mm., and its height (or sagittal axis) also 1"5 mm. It
is composed of an elliptical central chamber, an inner corona of eight radial chambers,
and an outer corona of four to eight concentric elliptical ring-chambers. These latter are
divided by two crossed centripetal furrows (a sagittal and a frontal notch) into four
rounded lobes (figs. 8, 9). These are systematically arranged in pairs. The left
anterior and right posterior lobes are smaller than the right anterior and left posterior.

Stigmata (fig. 8, pe). — The convex superior face of the pneumatocyst, which is
covered by the exumbrella, exhibits only three stigmata. These lie in a straight line
which crosses the major axis of the elliptical disc at a very small angle. The subcentral
stigma (_po) lies nearly in the top of the central chamber, and opens on the left side of
the base of the sail ; the second lies on the surface of the left anterior quadrant, and

REPORT ON THE SIPHONOPHOR^E. 81

the third on the right posterior quadrant of the pneumatocyst, each at the base of a
radial chamber (fig. 8, pe' anterior, pe" posterior stigma).

Tracheal (fig. 9, pt). — The concave inferior face of the pneumatocyst, which is in
close contact with the superior convex face of the centradenia, gives off eight small
bunches of tracheas, each composed of two to four. These are simple undivided tubules,
which arise from the periphery of the eight radial chambers of the pneumatocyst, and
enter into the centradenia, where they end in its exodermal parenchyma.

Centradenia (figs. 3, 4, uc, in profile ; fig. 5, uc, in vertical transverse section ; figs. 6
and 7 in horizontal section, fig. 6 through the inferior, fig. 7 through the superior part).
— The central gland, or the so-called " liver," has the form of a flat cone, strongly com-
pressed from the two lateral sides, or of a thick vertical triangular lamella, which is
somewhat sigmoidal, or slightly bent in an S-form. Its upper face is completely covered
by the campanulate pneumatocyst ; its lower face is in contact with the gastrobasal plate
of the central siphon (fig. 5, st), and the surrounding corona of sexual siphons.

The glandular parenchyma of the centradenia is composed in the superior half more
of entodermal canals, in the inferior half more of exodermal cells and cnidoblasts. The
vascular reticulum of the superior face exhibits a star of eight radial main vessels ; two of
these, opposite in the longitudinal axis of the disc, are longer and stronger than the six
others, which are disposed symmetrically on both sides of the former, three on the right,
three on the left ; the middle of these, or the frontal canal, is the shortest, whilst the two
diagonal canals of each side are longer than the latter, shorter than the sagittal canals.1
The numerous smaller vessels, which arise from these eight superior hepatic vessels, form
an irregular network, which is rather dense in the superior half of the centradenia, loose
in its inferior half ; the axial part of the latter is chiefly composed of exoderm-cells.

The descending superficial canals of the centradenia pass over at its basal periphery
into four different groups of canals : — (l) The numerous radial canals of the free mantle
border (or pallial canals, fig. 10, ce) ; (2) the canals of the tentacles (fig. 5, t) ; (3) the
canals of the gonostyles (gs) ; (4) the eight innermost canals which open into the base of
the central siphon.

The pallial canals (fig. 10, ce), which run nearly horizontally from the periphery of the
base of the liver to the edge of the mantle border, are very numerous, and so densely
attached one to another, that their intervals are smaller than their lumen. Their distal
ends, which open into the annular elliptical marginal canal (cc), are partly simple, partly
forked ; usually a simple and a forked vessel regularly alternating.

Central Siphon (fig. 2, so ; fig. 3, sa ; fig. 5, sa, in longitudinal section). — The large
central polypite is a slender inverted cone, strongly compressed from both sides. Its ellip-
tical basal plate is in contact with the basal face of the centradenia, and separated from
it by the strong fulcrum of the gastrobasal plate (fig. 5, st). The periphery of this is

1 Compare the figure of Bedot, 59, pL ix. fig. 1.

(ZOOL. CHALL. EXP. — PART LXXV1I. — 188-'.) Hbllh 11

82 THE VOYAGE OF H.M.S. CHALLENGER.

pierced by eight openings which conduct into the eight primary radial vessels, arising
from the original manubrium of the Medusa. The thick wall of the central siphon
exhibits eight strong radial longitudinal folds, and its slender proboscis has eight lips
around the terminal mouth (figs. 3, 5, so).

Gonostyles (figs. 2, 3, 5, gs). — The sexual siphons, sixteen in number, form an
elliptical corona around the central siphon and separate it from the tentacular zone and
the mantle-border. Their slender cylindrical basal part bears clusters of medusiform
gonophores, whilst their dilated spindle-shaped distal part opens by a four-lobed mouth.

Tentacles (figs. 1-5, t). — The sixteen tentacles form an outer corona around the inner
corona of gonostyles, and alternate regularly with the insertions of the latter. They are
simple, cylindrical, very contractile, and beset with two opposite rows of cnidoblasts.

Genus 8. Velella,1 Lamarck, 1816.
Velella, Lmk., Hist. nat. anim. sans vert., t. ii. p. 481.

Definition. — Velellidse with an elliptical or slightly quadrangular (parallelogram -
shaped) umbrella, and a vertical triangular sail, placed obliquely in a diagonal line of the
ellipse. Margin of the umbrella not lobate. Pneumatocyst discoidal, of the same form
as the surrounding umbrella, with a vertical chitinous crest supporting the sail. Sub-
marginal corona of tentacles simple.

The genus Velella is, next to Physalia, the oldest and best known form of all
Siphonophorse, since it is generally distributed in all warmer seas, often very common,
and in some countries used as food. Owina; to its striking form and sailing movement it
is well known to the fishermen. The Italian naturalists Ferrante Imperato (1599) and
Columna (1616) mention it under the names Vela or Velella, Carburius (1757) and
Dana (1776) under the names Armenista or Armenistarion. The first good description
and figure were given in 1776 by the excellent Swedish naturalist Forskal;2 he named the
Mediterranean species Holothuria spirans. Afterwards Lamarck erected the genus
Velella with three species (the Mediterranean Velella limhosa, the North Atlantic Velella
mutica, and the South Atlantic Velella scaphidia). Esckscholtz3 in his fundamental work
described ten different species, and Lesson4 as many as sixteen. But the greater part of
these descriptions are worthless and quite insufficient, since they are founded only upon
the different coloration and other characters of little value (for example, the different
direction of the sail).

Two species of Velella only are hitherto completely known ; the Mediterranean
Velella spirans, very accurately described by Kolliker5 and by Vogt,6 and the North
Atlantic Velella mutica by Alexander Agassiz.7

1 Velella = Diminutive of Vela, sailing-boat.

2 11, Taf. xxvi. fig. K. 3 ^ p 168j Taf. xv. 4 3, p. 563.

6 4, p. 46, Taf. xi. figs. 9-15. u 6, pis. i., ii. 7 57, pis. i.-vi.

REPORT ON THE SIPHONOPHOR^E. 83

The collection of the Challenger contains different species of Velella, collected in
widely distant parts of the Atlantic and Pacific Oceans. The comparison of these species
and of others which I have seen in many museums, has led me to the opinion that about
a dozen different " good species," at least " geographical species," may be distinguished,
and that these may be placed in two different genera, Velella (sensu stricto) and
Armenista.1 The genus Velella (sensu stricto), the type of which is the well-known
Velella spirans of the Mediterranean, has an elliptical umbrella with an integral, not
lobate margin, and a simple series of tentacles ; it stands nearer to the ancestral form
Rataria.

The second, more differentiated nd larger genus, Armenista, has a more quadrangular
or parallelogram-shaped umbrella, with a broad lobate margin, and a double or multiple
series of tentacles. Perhaps even four genera may be distinguished when the numerous
local varieties are better known.

The following species may be distinguished of the true Velella (sensu stricto) : —

(1) Velella spirans, Eschscholtz, 1 (Mediterranean).

(2) Velella caurina, Eschscholtz, 1 (North Atlantic, observed by me in 1866

in the Canary Islands).

(3) Velella scaphidia, Peron (12), collected by the Challenger in the Guinea

Current (Stations 346 to 352).

(4) Velella oblonga, Chamisso (21), collected by the Challenger off Volcano Islands,

south of Japan (Stations 229 to 237).

(5) Velella patella, Brandt (25), collected by the Challenger in the Tropical Pacific

(Stations 265 to 279).

Nearly related to the latter seem to be Velella pacifica of Eschscholtz and Velella
cyanea of Lesson (South Pacific).

The other species of Velella described seem to belong to the following genus,
Armenista.

Genus 9. Armenista? n. gen.
Velaria, Hkl., System der Siphonophoren, 1888, p. 31.

Definition. — Velellidse, with a quadrangular or parallelogram-shaped (sometimes
slightly elliptical) umbrella, and a vertical triangular sail, placed oblicjuely in a diagonal
line of the parallelogram. Margin of the umbrella lobate. Pneumatocyst discoidal, of
the same form as the surrounding umbrella, with a vertical chitinous crest supporting
the sail. Submarginal corona of tentacles double or multiple.

The genus Armenista (enumerated in my "System" as Velaria, a name already

1 The name Velaria adopted in my System der Siphonophoren, 1888, p. 31, had previously been employed for a
Sponge (Aplysinidae).

2 Armenista or Armenistarium (Carburius, 1757) is the Cephalonian term for sail= Velella.

84 THE VOYAGE OF H.M.S. CHALLENGER.

employed for a Sponge) comprises those Velellidse which differ from the true Velella by
the broad lobate margin of the umbrella and by the double or multiple corona of
tentacles ; usually also by the quadrangular form of the umbrella, which in the former is
more elliptical. Although a sharp boundary line between the true Velella (s. str.) and
Armenista cannot be drawn, the differences of the extremely divergent forms are very
striking ; and when the intermediate forms are neglected, they represent two widely
different genera. The elliptical umbrella with integral border of the mantle, and the
simple corona of tentacles, brings the true Velella nearer to the ancestral Rataria. On
the other hand, the larger Armenista, with the broad lobate border of the mantle of the
quadrangular umbrella, and the double or multiple corona of tentacles, is a more recent
and more differentiated form. To this genus belong probably the following species : —

(1) Armenista sigmoides, n. sp., from the Southern Tropical Atlantic, figured in

PI. XLIIL, and taken by the Challenger at Station 346.

(2) Armenista mutica, Lamarck, from the North-western Atlantic, very good

figures of which were published in 1883 by Alexander Agassiz (57).

(3) Armenista antarctica, Eschscholtz (1), and

(4) Armenista indica, Eschscholtz (1), from the Indian and Antarctic Oceans, and

the Cape of Good Hope.

(5) Armenista lata, Chamisso (21), from the Northern Pacific.

(6) Armenista lobata, n. sp., from the Southern Pacific.

Armenista sigmoides, n. sp. (PI. XLIIL).

Velella sigmoides, Hid., 1881, MS.

Habitat.— Station 346, Tropical Atlantic; April 6, 1876 ; lat. 2° 42' S:, long. 14° 47'
W. Surface.

Umbrella (fig. 1, from above; fig. 2, from below; fig. 3, half lateral, half superior
view). — The umbrella is nearly rectangular, with rounded edges, about once and a half
or twice as long as broad ; the longitudinal or sagittal diameter of the horizontal disc
is in the largest specimens 80 to 90 mm., the transverse or frontal diameter 30 to
40 mm. This latter about equals the height of the triangular vertical crest or sail.

Exumbrella (fig. 1). — The superior or apical face of the umbrella is divided into the
broad lobed mantle-border and the colourless pneumatic disc, both separated by a sharp
line which is not parallel to the margin of the border. The vertical diagonal crest
divides the exumbrella into two equal halves, an antero-dextral and a postero-sinistral.
When we regard the disc in profile from the broad side (its major axis perpendicular to
the axis of vision), the crest or sail runs from our proximal and left to our distal and
right side ; but seen from behind, from the smaller side (the major axis of the disc

REPORT ON THE SIPHONOPHOR^E. 85

parallel to the axis of vision), the vertical sail runs from our proximal and right to our
distal and left side (" Velella sinistra," Chamisso).

Limbus Umbrella} (fig. 1). — The broad soft border of the horizontal disc is widely
prominent over the edge of the pneumatophore, and has four deep marginal incisions.
Two opposite ones of these correspond to the diagonal axis of the sail (the macrodia-
gonal), and touch the two ends of its base ; the two others correspond to the diagonal
axis of the transverse or frontal groove (the brachydiagonal). The border of the mantle
is divided by these four marginal incisions into four large lobes, which are disposed in
pairs. The two lateral lobes (right and left) are nearly rectangular, and much smaller
than the two crescentic sagittal lobes (anterior and posterior). Besides these four deep
marginal incisious, which correspond to those of the edge of the pneumatophorous disc,
the margin of the mantle-border often exhibits four smaller incisions alternating with
the former ; but these are not constant.

Subumbrella (fig. 2). — The inferior or basal face of the umbrella exhibits the smooth
and lobed mantle-border to the same extent as the upper face. A deep elliptical
incision, the tentacular or submarginal furrow (ut), separates it from the elliptical central
area of the subumbrella. This area is bisected by the longitudinal axis of the spindle-
shaped, long and narrow centradenia and the base of the central siphon. Numerous sexual
siphons occupy the greatest part of that subumbrellar central area, whilst a double or
triple corona of tentacles surrounds it.

Margin of the Sail. — The triangular vertical sail is composed of an inner chitinous
crest arising from the pneumatocyst, and of a canaliferous plate of the exumbrella,
covering the two sides of the former. This plate is prolonged over the free margin of
the crest, and borders it as a soft contractile limb, which is the uppermost part of the
original longitudinal mantle-fold.

Pneumatocyst (fig. 5, from above; fig. 6, from below; fig. A,p, in vertical section). —
The pneumatocyst is composed, as in all species of Velella and Armenista, of two different
parts, the horizontal discoidal float filled with air, or the pneumatodisc, and the vertical
triangular crest, which is the inner skeleton-plate of the soft sail, perpendicular to the
disc, and placed in its greater diagonal.

The pneumatodisc, or the horizontal float, is sometimes elliptical or nearly rec-
tangular in outline, at other times distinctly S-shaped. It is two and a half times as
long as broad ; in the largest specimen 50 to 60 mm. long, 18 to 21 mm. broad.

The four characteristic marginal incisions, which are described above of the mantle-
border, are marked also in the periphery of the pneumatodisc (fig. 5) ; the two notches
of the macrodiagonal touch the two ends of the base of the crest, whilst the two notches
of the brachydiagonal approach the two ends of the frontal furrow. The four cmadrants
of the disc, which are separated by these four diagonal notches, are disposed in pairs
opposite ; the two lateral pairs form an oblique triangle with concave base, and their

86 THE VOYAGE OF H.M.S. CHALLENGER.

surface occupies less than half the area of the two opposite sagittal pairs (posterior and
anterior) ; these form a much broader oblique triangle with a prominent convex base.

The superior or apical face of the disc is slightly convex, the inferior concave ; the
convexity is much stronger in younger specimens (fig. 4) than in older (fig. 3).

The central chamber of the pneumatocyst (fig. G, ph) exhibits nearly the same
form as that figured in Rataria cristata (PI. XLIV. figs. 8, 9). It is elliptical and dis-
tinctly octolobate. The deep frontal furrow proceeds near to the central chamber, so that
the octoradial ring is bisected by it ; its ventral half is composed of two anterior and two
left chambers ; its dorsal half of two posterior and two right chambers. Each of the eight
radial chambers possesses a branched trachea, arising from the periphery of its basal side.
The apical side of the octolobate ring, however, exhibits three stigmata only, placed near
the macrodiagonal, one subcentral, an anterior upon the left ventro-lateral, and a posterior
upon the right dorsolateral chamber.

The concentric elliptical ring-chambers, which surround the octolobate central part of
the float, are sixty to eighty in number in the largest specimens ; those of the central and
those of the peripheral part are half as broad as the intermediate chambers placed between
them. Each elliptical ring-chamber is deeply bisected by the frontal furrow of the brachy-
diagonal. All elliptical ring-chambers communicate with one another by two opposite
openings or pneumothyrae, which are placed one on each pole of the sagittal axis (fig. 5,pg).

The stigmata, or the external openings of the exumbrellar face of the float, are placed
in one straight line, very near the base of the vertical crest, and this line bisects the latter
at a very small angle (fig. 5, pe). There are in the largest specimen (besides the central
stigmata) about thirty to forty stigmata opposite in pairs ; these are situated, the half
in the right ventral quadrant of the disc (to the right of the basis of the crest) ; the other
half in the left dorsal quadrant (to the left of the basis of the crest).

The tracheae, which arise from the inferior face of the disc, are not numerous.
Besides the eight above-mentioned tracheae, which usually arise from the octolobate ring
(fig. 6, pt), there is in some specimens another corona of sixteen tracheae, which arise from
the sixth or ninth ring, or between these. But in other species there is no regular arrange-
ment, a few scattered tracheae arising here and there from one of the middle chamber-
rings. In a few specimens I found an oblique double series of tracheae arising along the
frontal furrow, on both sides of it. The number, size, disposition, and branching of the
tracheae seem to be subject to many variations in this as well as in other species of the
Velellidae. Some tracheae are very long (about equal to the diameter of the centradenia),
and bear ten to twelve or more irregular and curved branches (fig. 10) ; others are much
smaller, and bear only a few short branches. The majority of tracheae run more horizontally
beyond the pneumatocyst, and finish in the glandular tissue of the centradenia ; but
a few larger tracheae pierce this latter, and enter partly into the exodermal wall of the
central siphon, partly in that of the gonostyles, where they end in their proximal half.

REPORT ON THE SIPHONOPHORiE. 87

The Centradenia (fig. 4, uc; fig. 7), or the so-called liver, is a lanceolate gland, the
upper convex surface of which is flatly conical, and fills up the inferior concave face of
the pneuniatocyst (fig. 4, #/). Its lower flat horizontal face forms the roof of the central
siphon, and is separated from its base by the gastrobasal plate, a thick structureless
fulcrum (fig. 4, st). The periphery of this plate is pierced by sixteen radial main canals,
which arise from the lanceolate base of the central siphon in two longitudinal rows,
and run along the subumbrella towards its margin ; they give off at their base sixteen
ascending liver-canals, which run in the convex upper surface of the centradenia towards
its conical apex, where they unite and form a central " liver-star." Very numerous
lateral branches, which arise everywhere from these main canals, penetrate into the sobd
exodermal parenchyma of the centradenia, and form a very dense network by innumer-
able anastomoses. The vessels in the upper and outer (hepatic) part of the central
gland are dark brown or black, thickly filled with pigment-granules (fig. 4, uh), except
the uppermost ; whilst the canals in the lower and inner (renal) part are white or
colourless, and contain numerous small greenish guanin-crystals (fig. 4, un).

Central Siplion (fig. 2 ; fig. 4, sa ; fig. 7, sa). — The large central polypite is inversely
conical, sharply compressed from both sides, very contractile, and variable in form and
size. Its lanceolate roof is nearly half as large as the adjacent basal face of the centra-
denia, and separated from it by the structureless fulcrum or the gastrobasal plate. Its
muscular wall is very thick, and exhibits in some specimens outside eight or sixteen thick
longitudinal ribs, which are prominent inside as deep grooves. The opening of the mouth
has often eight triangular lips (fig. 4, so).

The periphery of the lanceolate base of the central siphon exhibits sixteen openings,
which conduct into the sixteen radial main vessels of the subumbrella ; two opposite of
these gastral canals lie nearly in the sagittal axis of the subumbrella (one ventral and
one dorsal), and these are much wider and longer than the fourteen other vessels which
arise symmetrically from both sides (fig. 7).

Canal System (fig. 7). — The reticular system of anastomosing gastro-canals, which
arise from the branches of the sixteen above-mentioned radial main canals, is in this, as
in other large Velellidae, very complicated. The following principal branches may be
distinguished : — (l) The sixteen ascending superficial canals, which pass off from the
former immediately at their origin, and end centripetally in the upper face of the
centradenia ; (2) very numerous canals which form a dense reticulum in the sub-
umbrella ; (3) numerous vessels which arise from the peripheral part of the centradenia,
and enter into the gonostyles; (4) a smaller number of vessels, outside the latter, which
open into the tentacles ; (5) a corona of radial submarginal vessels which run in the
peripheral part of the subumbrella, between the tentacular zone and the margin ; these
open into (6) a marginal ring-canal, which runs inside the series of marginal glands ;
(7) a coronal canal, or inner submarginal ring-vessel, runs in the furrow between

88 THE VOYAGE OF H.M.S. CHALLENGER.

border and tentacular zone ; from this arise (8) the numerous mantle-vessels of the
exumbrella, which form a dense network in the latter, and from these arise (9) the
mantle-vessels of the vertical crest, which form a dense network of different form on its
two sides ; four of these crest-canals are much stronger than the others, two opposite
longer, which run along the free upper edge of the crest, and two opposite shorter, which
bisect the triangular sides of the crest, and arise near the centre of the frontal groove ;
(10) a double series of elegant pinnate sail-canals, which arise from the large superior
edge-canal of the crest, and run in the soft sail border towards its free margin ; they are
here united by a small outermost canal running in the free edge of the sail. The special
form and reticulation of these numerous canals is about the same as figured by Alexander
Agassiz ' in Velella (Armenista) mutica.

Gonostyles (fig. 2 ; fig. 4, gs ; fig. 8, gs). — The small sexual siphons, or "gonoblastidial
polypites," are very numerous (many hundreds in the larger specimens) and densely
crowded, occupying the entire broad gonostylar zone between the base of the central siphon
and the corona of tentacles. Their upper or proximal half is cylindrical, and covered
with bunches of medusiform gonophores (g) ; their lower or distal half is a contractile
muscular stomach, beset with sixteen longitudinal rows of cnidonodes ; its proboscis
opens below by a very extensile mouth, and this is sometimes distinctly lobed (fig. 8, so).
The special form and structure of the gonostyles is the same as figured by Alexander
Agassiz 2 in Velella (Armenista) mutica.

Tentacles (figs. 1-4, t). — The corona of tentacles, placed in the elliptical groove
between the outer edge of the gonostylar zone and the inner edge of the broad mantle-
border, is composed of two or three rows of tentacles ; those of the innermost row are
the largest, and in the expanded state about as long as the transverse diameter of the
umbrella. The tentacles of the outer row, alternating with the former, are only half as
long ; and when there is a third outermost row, these are very short. The form and
structure of these cylindrical tentacles are the same as in other Velellidge ; they are beset
on both sides with two lateral rows of sessile cnidocysts.3

Armenista sigmoides, as described above from the Tropical Atlantic (Station 346),
is perhaps identical with a Velella of which I have obtained several specimens from
Cape of Good Hope, collected by Dr. W. Bleeck. The short description and the figures
which Eschscholtz (1) has given of Velella indica (also occurring at the Cape) are not
sufficient to decide the question of the identity of these species. Further accurate
examinations and comparative studies are required to enable a better distinction of
the different species of Disconectse.

1 57, pis. iv., v. 2 57, pi. ii. 3 Compare Kolliker, 4 ; Vogt, 6 ; Huxley, 9 ; Agassiz, 57.

REPORT ON THE SIPHONOPHOR^E. 89

Subclass II. SIPHONANTH^.

Order II. CALYCONEOLE, Haeckel, 1888.
(Pis. XXVII.-XLII.)

Dijihyidx, Eschscholtz, 1829, 1, p. 122.
Calycophoridx, Leuckurt, 1854, 8, p. 256.

Definition. — Sipkonophorse with one or more nectophores, without pneumatophore,
and without palpons. Nectosome always without pneumatocyst, represented only by
the nectophores. Siphosorue either a single siphon (Monogastricaa) or a long tubular
stem, bearing a series of equidistant siphons, separated by free internodes (Polygastricse).
Each siphon with a single tentacle bearing a series of tentilla or lateral branches ; each
tentillum with a cnidosac and a simple terminal filament.

The order Calyconectse, hitherto usually called Calycophoridae, comprises all Siphono-
phorse without pneumatophore. No doubt this large group is very natural ; it differs
from all the other Siphonophorse, not only in the complete absence of the important
pneumatic apparatus, but also in a number of other peculiarities. The primary larva
develops first a nectophore (in the others a pneumatophore). The siphons have always
the same structure, and so also the single tentacle, which is attached to each siphon ; it
bears a naked cnidosac (without involucrum) of a constant structure. The long tubular
stem of the polygastric Calyconectse always bears a single row of ordinate cormidia,
separated by naked free intervals. Each cormidium constantly bears a single siphon
only, and a single tentacle. Palpons and palpacles never occur in the Calyconectse.

History. — Eschscholtz, in his fundamental work,1 divided the order Siphonophorse
into three natural families ; the first of these, Diphyidse, differs from the two other
(Physophoridse and Velellida?) in the complete absence of any float filled with air. He
distinguished six different genera ; three of these (Eudoxia, Erssea, Aglaisma) are
monogastric ("with a single suctorial tube") ; the three others (Abyla, Cymba, Diphyes)
are polygastric (" with a long digestive tube bearing numerous suctorial tubes ").

The oldest known of these six genera was Diphyes, founded by Cuvier in 18 17,2
upon an apparently double animal, or twin-zoophyte, of which Bory had given the first
figure in 1804 under the name Biphora bipartite (13) ( = Diphyes dispar, Chamisso).

Lesson adopted in 1843 (3, p. 424) the system of Eschscholtz, and divided the family
Diphyidae also into Monogastricse and Pol ygas tricse. But he distinguished a greater
number of genera and subgenera (partly constituted already in 1827 to 1833 by Quoy
and Gaimard, 2 and 20). Lesson collected all the scattered descriptions of Diphyidee

1 System der Acalephen, 1829, p. 122. - Regne animal, edit, i., tome iv. p. 61.

(ZOOL. CILALL. EXP. — PART LXXVII. — 1888.) Hhhli 12

90 THE VOYAGE OF H.M.S. CHALLENGER.

published up to his time ; but he could not distinguish the natural groups critically.
Marked progress in our anatomical knowledge of the Calyconectae was made by the
excellent descriptions of different Diphyidae which were published in the third period of
our knowledge of Siphonophorse (from 1853 to 1859, 4-10) by Kolliker, Leuckart, Vogt,
Gegenbaur, and Huxley. Two of these celebrated zoologists simultaneously and inde-
pendently discovered, in the spring of the year 1853, that the monogastric Diphyidae,
or the so-called Eudoxise, were the isolated individual groups (or cormidia) of the
polygastric Diphyidae, detached from the common stem, and that the former were
connected with the latter by a regular metagenesis. Gegenbaur observed in Messina the
detached Eudoxise of Abyla pentagona.1 The same observation was made at the same
time in Nice by Leuckart, who further demonstrated that the monogastric Eudoxia
campanula was the detached sexual zooid of his Diphyes acuminata (5, pp. 41, 69).

Leuckart in the next year (8, p. 256) replaced the name Diphyidae by the more con-
venient term Calycophoridae, and united in this family the true Diphyidae (with two
nectophores, loc. cit., p. 257) and the Hippopodidae (with a biserial nectosome, composed
of four or more nectophores, loc. cit., p. 298). The latter were formerly regarded as a
separate family of Physophoridae, though they possess no float filled by air.

Huxley in his great work (9, 1859) adopted the main group Calycophoridae, and
opposed it to all other Siphonophorae or Physophoridae. He gave the first exact descrip-
tion of many hitherto incompletely known forms, mainly Abylidae. He was also the first
to describe a very remarkable Calycophoridj which possesses only a single permanent
nectophore, under the name Sphieronectes kollikeri, and rightly regarded it as the type
of a new family, Sphaeronectidae.2 Fifteen years later a very similar species of the same
genus was described by Claus under the name Monoplxyes gracilis (70, pi. iv.). He
observed its metagenesis and connection with that Eudoxia which Gegenbaur had
described in 1854 as Diplophysa inermis.3 The peculiar family represented by these
Calycophoridae, the Sphaeronectidae of Huxley, was called by Claus Monophyidae, in opposi-
tion to Diphyidae. Following the systematic manuals of recent years, I adopt the term
Monophyidae for all those polygastric Calyconectae which possess only a single permanent
nectophore, while I restrict the term Diphyidae to those forms which have two permanent
nectophores. A third family is formed by the Hippopodidae,4 which possess numerous
(at least three or four) nectophores arranged in a biserial nectosome ; they were afterwards
named Polyphyidae by Chun (86, p. 12).

The Polyphyidae differ from the other Calycophoridae in the lack of bracts. A new
group, described in the secpael as Desmophyidae, is intermediate between the Diphyidae
and Polyphyidae, having in common with the former the possession of a bract on each
eudoxome, with the latter a biserial nectosome, composed of numerous nectophores.

1 7, p. 295 ; 4, p. 78 ; 31, p. lot!. " 9, pp. 29, 50, pi. iii. fig. 4.

3 7, Taf. xvi. fig. 3. * Kolliker, 4. p. 28.

REPORT ON THE SIPHONOPHORiE. 91

111 the numerous voyages which I have made during the past twenty-five] Jyears, in
order to complete my System der Medusen (compare the Preface to that Monograph), I
have found also many opportunities of examining a great number of Calyconectse belonging
to all the genera described in the following pages. The richest harvest was reaped during
my residence in the Canary Islands (December 1866 to February 1867), where I was
able to examine accurately a great number of new or imperfectly known Monophyidse,
Diphyidae, and Polyphyidae. I there traced the complete metagenesis of many typical
genera and the ontogenetic connection of monogastric and polygastric Calyconectse.
Supported by this rich personal experience, I have in the following pages attempted to
give a more correct definition of genera and a more natural arrangement than has hitherto
been possible.

Nectophores. — The Calyconectse differ from all other Siphonophorse in the complete
absence of any pneumatophore, so that the nectophores are the only organs of locomotion.
The polygastric Calyconectse bear on the top of the long tubular stem either one or two
large nectophores (Monophyidse and Diphyidae), rarely a biserial nectosome, which is
composed of two opposite rows of nectophores, four to six or more (Desmophyidas and
Polyphyidae). The locomotion of the monogastric Calyconectse is effected usually by the
subumbrella of the gonophores (Eudoxidaa) ; but in the Ersseidae the first-formed
gonophore loses its sexual functions, and acts as a " special nectophore."

The larva of the Calyconectse, which develops from the fertilised egg, and which we
call Calyconula (PI. XXVII. figs. 8-11), is a bilateral medusoid person, the manubrium
of which Hes outside the campanulate umbrella, apparently protruded through a ventral
fissure of the latter.1 The " primary nectophore " of this Calyconula often (perhaps
always) becomes detached, and replaced by a secondary nectophore, which is often
heteromorphous.

The number, arrangement, and form of the nectophores in the different Calyconectse
are very variable, and serve mainly for the distinction of genera. Eegarding the
general form of the nectophores, we may distinguish two different main groups, Sphsero-
nectarise and Cyrubonectarise ; the umbrella of the former consists of a very soft jelly,
and is subspherical, mitrifurm or reniform, always devoid of distinct edges, with rounded
surface. The umbrella of the latter, on the contrary, has always a definite geometrical
form, and is polyhedral, either pyramidal or prismatic, with polygonal faces and sharp,
often denticulate, edges ; its jelly-substance is rather hard and firm, often cartilaginous.

Nectosac and its Canals. — The original form of the muscular subumbrella in the
Calyconectse is hemispherical, but usually in correlation with the fundamental form of
the nectophores (primary as well as secondary umbrella) it is more or less bilateral,
and at the same time quadriradial ; the latter structure (inherited from the ancestral
Anthomedusse) is indicated by the constant four radial-canals of the subumbrella ;

1 7, Taf. xvi. fig?. 12-21 ; 85, Taf. vi., vii. ; 86, Taf. xviL figs. 6, 7.

92 THE VOYAGE OF H.M.S. CHALLENGER.

and these are always so differentiated, that two opposite lateral vessels (right and left)
are symmetrical, different from the two sagittal vessels (shorter ventral and longer
dorsal canal). The sagittal plane, which divides the bod)'' of the nectophore into right
and left halves, is therefore precisely marked by the two latter opposite canals.
Usually both halves are symmetrical, but sometimes more or less asymmetrical. The
velum which surrounds the ostium of the muscular nectosac is usually rather broad and
strong. The four radial canals are connected above the insertion of the velum by a
constant circular canal.

Pallial Canals. — Besides the four constant radial canals, there are in many Caly-
conectae one or two pallial canals or nutritive vessels of the jelly-substance of the
nectophore. An apical pallial canal runs in many Diphyopsidse from the top of the
nectosac to the apex of the umbrella. Praya and others have two pallial canals at the
ventral side, an ascending and a descending.

Number and Arrangement of the Nectophores. — The number of the swimniing-
bells, and their arrangement on the top of the stem, are employed by modern authors to
divide this order into three families : — Monophyidae, Diphyidae, and Polyphyidae. The
Monophyidae (or Sphaeronectidae) possess a single large nectophore on the top of the
stem ; this is smooth and without distinct edges in the true Sphaeronectidae, sharp-edged
or pyramidal in the Cyrnbonectidae.

The Diphyidae, comprising the great majority of genera and species (among the living
Calyconectae), have always two large nectophores on the top of the stem. These are
opposite, of nearly equal size and similar form, with rounded exumbrella, in the subfamily
Prayidae. They are also of nearly equal size and similar form in the subfamily
Diphyopsidse ; but in this group the exumbrella is sharp-edged, pyramidal, and the two
nectophores are not opposed, but one placed behind or below the other. The remarkable
subfamily Abylidse is distinguished by two nectophores of very unequal size and
dissimilar form ; the first or anterior being much smaller than the second or posterior.
The form of the two very different nectophores becomes in this group extraordinarily
strange and complicated.

The Polyphyidae (or Hippopodidae) and the closely allied Desmophyidae are dis-
tinguished from the other Calyconectae by the possession of a biserial nectosome, similar
to that of most Physonectae. There are here at least four to six nectophores (some-
times ten to twelve or more), arranged in two opposite series. They have here no definite
edges, and are mitriform or reniform in Desmophyes, Hippopodius, and Polypkyes ;
whereas they are angular (pentagonal), prismatic, or pyramidal in Vogtia.

It may be that all the Calyconectae with rounded nectophores represent a natural
suborder of this order (Sphaeronectariae), and all the others (with edged or pyramidal
nectophores) another suborder (Cymbonectariae). The first suborder (Sphaeronectariae)
comprises the Sphaeroncctidae, Prayidae, Desmophyidae, and Hippopodidae. The second

EEPOET ON THE SIPHONOPHOE^E. 93

suborder (Cymbonectaxise) would include the Cyinbonectidae, Diphyopsidae, Abylidae,
and Vogtidae.

Hydrcecium or Infundibulum (funnel cavity, house-room, Gehauskammer, Trickter-
hohle, Stammbehalter). — All polygastric Calyconectse possess a protective cavity, into
which the contracted siphosome may retire. This hydrcecium (or infundibular cavity)
is always an external space, filled with sea-water and invested by the exoderm. In
the Monophyidae it is originally an open groove or fossula on the ventral side of the
single nectophore {Monophyes, Cymbouectes, PL XXVII. ). This open groove, or the
" hydroecial sulcus," becomes a closed cylindrical or conical canal, by concrescence of the
two opposite margins, or by deeper invagination of the exodermal fossula, in another
part of the Monophyidae {Sphzeronectes, Muggizea, Cymba, PL XLL). The singular
genus Mitrophyes (PL XXVIII.) has no hydrcecium, but it is replaced here by a pouch-
like space between the permanent secondary nectophore and a mitre-shaped or scutiform
bract, which is the remnant of the reduced primary nectophore.

The hydrcecium of the Diphyidae exhibits various degrees of development. In the
Prayidae it is an incomplete canal, formed by two opposite ventral grooves of the two
nectophores, fitting one into another. Diphyes, Diphyopsis, and the Abylidae possess a
conical infundibular cavity at the ventral side of their first or apical nectophore, and this
continues into an incomplete hydrcecial canal, formed by a longitudinal groove at the
ventral side of the second or basal nectophore. The two margins of this groove are
often partly united by concrescence, so as to form a shorter or longer canal. In other
cases the two opposite margins of the hydrcecial groove are developed in the form of two
broad dentate plates (right and left) which overlap one another. The genus Galeolaria
has no hydrcecium, the siphosome hanging freely down between the distal end of the first
and the proximal end of the second nectophore.

The hydrcecium of the Desmophyidae and Polyphyidae is an infundibular cavity
between the two opposite rows of nectophores, almost as in the Prayidae.

Somatocyst or Acrocyst (top-cavity of the stem, coryphal cavity ; Saftsack, Saftbe-
halter, cs). — The single nectophore of the Monophyidae, and the first or proximal nectophore
of the Diphyidae, contains a remarkable cavity, the acrocyst or somatocyst, at the ventral
side of its nectosac and at the top of its hycLrcecium. This is the uppermost part of the
common trunk included in the jelly-substance of the first nectophore ; it may be com-
pared to the apical canal or peduncular canal of the ancestral Medusa, which was con-
nected by it with its hydropolyp-parent. The somatocyst is usually spindle-shaped or
ovate, at other times subspherical or cylindrical ; its upper or apical end is blind, whilst
its lower or basal end passes directly into the small apical central cavity, from which
arises the central canal of the stem and the pedicular canal of the nectosac.

The narrow cavity of the somatocyst, or the acrocyst-canal, is invested by very large
entoderm cells, usually vacuolated and polyhedral owing to mutual compression. Its

94 THE VOYAGE OF H.M.S. CHALLENGER.

uppermost part usually includes a smaller or larger oil globule, the oleocyst (co). The
physiological function of the somatocyst may be hydrostatic (as a float) and nutritive
(as an accumulation of nutritive, strongly refracting albuminous globules). Its morpho-
logical nature is explained by the medusome-theory which compares it with the apical
canal or original peduncular canal of a Medusa-person.

Trunk or Ccenosarc. — The common stem in all polygastric Calyconectse is a long
cylindrical and highly contractile tube, very long and thin in the expanded state, short
and thick in the contracted state, when it is retracted into the hydroecium. The cormidia
are always ordinate, arranged in a single series on the ventral side of the articulated stem ;
they are separated by free naked intern odes of equal length. Very rarely (in Polyphyes)
the cormidia begin to be scattered. The number of the cormidia is in the smaller cormi
ten to twenty (rarely less), usually forty to eighty or more, sometimes several hundreds.
In the largest species (mainly of Praya) the expanded stem attains a length of more than
a metre. The structure of the stem-wall is that usually found in the Siphonanthse ; the
tubular fulcrum (or structureless supporting plate) is invested on its inner side by a thin
layer of entodermal circular muscles, on the outside by a strong layer of exodermal longi-
tudinal muscles ; these are arranged, as usual, in parallel bundles along the lamellar
radial folds of the fulcrum.

Cormidia. — The aggregation of different medusoid persons, by which the cormus of
the Calyconectse is formed, follows certain simple and regular laws, but is different in
the two kinds of cormidia, which we distinguish as Eudoxomes and Ersseomes. The
cormidia of the great majority of Calyconectse are Eudoxomes, or in the free inde-
pendent state " Eudoxise " or " Diphyozooids " ; each Eudoxome is a twin-group, composed
of two medusoid persons, a fertile and a sterile medusome. The sterile medusome is
composed of a bract, a siphon, and a tentacle. The fertile medusome is represented
originally by a single medusiform gonophore, but afterwards this is often replaced by a
cluster of several gonophores.

The Ersseomes (or the monogastric generation of Lilyopsis and Diphyopsis) differ
from the Eudoxomes in the fact that the primary gonophore loses its sexual manubrium,
and is converted into a so-called " special nectophore " ; its sexual function is replaced
by a secondary gonophore. The Ersseome, therefore, is composed of three medusoidal
persons, a sterile medusome (bract, siphon, and tentacle), a sterile nectophore, and a
fertile gonophore. Afterwards the latter is often replaced by a cluster of several
accessory gonophores.

The sessile gonophores of the Eudoxomes and Ersseomes attain sexual maturity, whilst
attached to the trunk, in Mitrophyes and Cymbonectes among the Monophyidse, Praya
and Gaholaria among the Diphyidoe, probably in all Desmophyidse and Polyphyidse.
This is not the case in the majority of Monophyidse and Diphyidse. Here the cormidia
become detached from the common stem before reaching maturity, and swim freely

REPORT ON THE SIPHONOPHOR^E. 95

about under the individual form of self-subsistent monogastric Calyconectae (Eudoxia
and Erssea, Families IV. and V.).

Bractese or Hydrophyllia (Protective persons or shields, Protecta, Pkyllozooids —
" Deckstiicke, Decksckuppen " of German authors). — Three families of polygastric
Calyconectae, tke Monopkykke, Diphyidae, and Desmophyidae, possess constantly a single
bract on each cormidium ; it is wanting only in the fourth family, Polyphyidse, where it
kas been lost by reduction. Tke single bract of eack cormidium is tke reduced umbrella
of tke Medusa-person, tke manubrium of which is the single siphon of the former. This
is very obvious in Praya, Ccdpe, and some other genera, where the bract still possesses four
radial canals. Usually some of these canals are lost, or they have disappeared altogetker.

Eack bract kas a convex exumbrella and a concave subumbrella, both separated
by the basal margin of tke umbrella. Tke form of the bract is very various, and
characteristic of the single genera of monogastric Calyconectae ; usually it corresponds
more or less to tke form of tke first nectopkore. It is hemispherical, mitriform or
subspherical, with a smooth exumbrella, in the polygastric Spkaeronectidae, Prayidae,
and Desmophyidae. The bract is pyramidal, spathiform or conical, with sharply
edged exumbrella, a ventral fissure, and a pointed apex in tke Cynibonectidae and
Diphyopsidae ; it is prismatic with polygonal faces and sharp edges in the Abylidae.

The bracteal cavity corresponds with the subumbrellar cavity of the ancestral Medusa,
but has lost its important muscle-plate ; it embraees the siphon, the single tentacle, and
the gonophore ; the last is placed at the ventral side of the siphon, the tentacle at its
dorsal side. The nutritive canals of all the organs unite in the top or the centre of the
bracteal cavity, where it communicates also with the central canal of the common stem
by a short bracteal canal. From tke same point arises also tke pkyllocyst,

Pliyllocyst. — Tke apical cavity or corypkal cavity of tke bract, which we call shortly
" pkyllocyst," corresponds to tke acrocyst or somatocyst of tke nectopkore. Its form and
tke number and disposition of its apophyses are often very characteristic of the individual
genera of Calyconectae. Usually tke pkyllocyst is an ovate or spindle-skaped sacculus of
tke same structure as tke acrocyst, filled witk large polyhedral vacuolated cells, and
often containing also an oleophore or an apical oil-globule. It arises usually more
or less vertically from the top of the subumbrellar cavity, and projects into the thick
jelly- substance of tke bract. From its base arise sometimes four radial canals, wkick
correspond to tke four original subumbrellar radial canals of tke nectopkorcs, in Praya
(PI. XXXII. figs. 8, 9) and in Calpe (PI. XL. figs. 14-18). These are so arranged that
two paired canals lie on both sides of tke bilateral bract (rigkt and left), and two odd in
tke sagittal plane (dorsal and ventral). Tke majority of tke Calyconectae do not now
possess tke four original canals. Cyniba and Abyla have only two lateral canals;
Bassia a single basal canal, arising from tke base of the pliyllocyst ; often they are
entirely lost (Diphyes, Monophyes. &c).

96 THE VOYAGE OF H.M.S. CHALLENGER.

The genus Mitrophyes among the Monophyidse (PI. XXVIII.) differs from all other
Calyconectse in the remarkable peculiarity that the convex exumbrella of the single
nectophore is covered by a large concave scutiform bract, and that the contracted
siphosome is retracted into the space between the former and the latter. We may
assume that here the primary nectophore of the larva, instead of being lost, is converted
into a permanent bract.

Siphons or Polypites. — Each cormidium of the Calyconectse possesses constantly only
a single siphon, and this is the manubrium of the medusome, the modified umbrella of
which is the bract. A single long tentacle is always attached to the base of the siphon,
between its dorsal side and the concave bract- wall. When the cormidium is detached
from the common stem, and represents an independent free Eudoxia or Erssea, it is
therefore called a " Monogastric Calyconecta."

The siphons of all Calyconectae are of similar form, of moderate or small size, very
contractile. The four segments or parts of each siphon are usually very distinct, viz.,
(1) a short peduncle to which is attached the tentacle ; (2) a hemispherical or subspherical
basigaster with a thick wall ; (3) an ovate or ellipsoidal stomach ; and (4) a very mobile
proboscis with the terminal mouth. (Compare PI. XXVII. fig. 8, &c.)

The pedicle of the siphon (sp) is usually very short, sometimes rudimentary, and
connects as a narrow cylindrical canal the gastral cavity of the former with the common
alimentary cavity of the stem. The tentacle arises from it sometimes more proximally,
at other times more distally ; sometimes even more from the following part.

The basigaster (sb), or the bulbous basal portion of the siphon, is usually subspherical
or ellipsoidal, and distinguished by a much-thickened exodermal wall ; this is filled with
innumerable densely crowded nematocysts. Its outer and inner surfaces bear a vibratile
epithelium. Its small ovate cavity is separated from the stomach by a pyloric valve,
which can be closed completely.

The stomach (sin) is ovate or ellipsoidal, with a thin, non-ciliated exoderm ; its
entoderm, however, is very thick, glandular, and often exhibits eight or sixteen hepatic
stripes (often of a yellow, red, or orange colour), sometimes instead of these hepatic
villi ; some of the entoderm cells are usually vacuolate.

The proboscis (sr) or the distal portion of the siphon, is very contractile and extensile,
with a strong muscular plate ; its free distal end opens through the mouth. The very
mobile mouth may be expanded in the form of a suctorial disc, circular, or polygonal ;
it is often octolobate (more rarely with four, twelve, or sixteen lobes).

Tentacles. — The capturing filaments or tentacles of the Calyconectse exhibit in all
members of this order essentially the same structure, and are very uniform, compared with
the manifold and richly varied forms which we find in the similar tentacles of the
following order — Physonectse. In all Calyconectse, without exception, each siphon bears
at its base a single, tubular, very long and extensile tentacle, which is beset with a single

REPORT ON THE SIPHONOPHOR^E. 07

series of lateral branches or tentilla. Each tentillum is a thinner cylindrical tubule, and
is constantly composed of three different parts — (1) a thin pedicle or proximal portion
(tp), (2) an inflated cnidosac as a dilated middle part (tk), and (3) a thin distal portion, the
terminal filament ((/'). The closed distal end of the latter is sometimes vesicular; so
also the distal end of the pedicle is sometimes club-shaped. The structure of the thin
cylindrical pedicle and of the long terminal filament is simple and always the same,
whilst the cnidosac, placed between them, exhibits a complicated, and more or less varied
structure (compare PL XXVII. fig. 7 ; PI. XXVIII. fig. 8 ; PI. XXXII. figs. 12-14 ;
PI. XXXIV. fig. 18 ; PI. XXXVI. fig. 26 ; PI. XXXVIII. fig. 16 ; PI. XL. figs. 19, 20).

The cnidosac (or sacculus) of all Calyconectas is originally nothing more than an
inflated dilatation of the middle part of the simple cylindrical tubular tentillum. This
dilatation seems to be produced by the stronger development of larger cnidocysts on one
side of its middle part. This side, which contains the so-called " cnido-battery," is the
convex dorsal side of the cnidosac, whilst the opposite ventral side is usually more or less
coneave ; it contains two parallel elastic bands, which seem to form together a noose at
the distal end of the cnidosac, the so-called " cnido-band or angle-band." The whole
cnidosac, therefore, has a bilateral form, usually more or less ovate, pyriform, or kidney-
shaped. In most Calyconectse it is more or less compressed from both sides, so that the
sagittal axis is larger than the frontal, but smaller than the principal axis.

The differentiated cnidocysts, or thread-cells, which are crowded in great numbers in
the '" cnido-battery " at the convex dorsal side of the cnidosac, occur generally (probably
in all Calyconectte) in three different forms — (1) very numerous, small, and palisade-
shaped (paliformes) ; (2) few, large, and sabre-shaped (ensiformes) ; (3) small and pear-
shaped, in a distal group (pyriformes). These are so arranged that several parallel rows of
paliform or medial cnidocysts occupy the whole convex dorsal side of the cnidosac (Jem),
two bilateral groups of a few large ensiform cnidocysts are placed at each side of its
proximal basal part (kg), and an odd distal group of small pyriform cnidocysts (kp) lies
at its distal end, at the base of the terminal filament (tf).

The small palisade-shaped or medial thread-cells (Cnidocysts paliformis, Am) are
always very numerous, usually some hundreds in number, and comprise far the greatest
part of the crescentic cnido-battery, occupying the dorsal half of the sacculus. They
are arranged so regularly that they form together a certain number (usually four, six, or
eight) of parallel longitudinal columns, each composed of a single series of numerous (twenty
to fifty, or more) cnidocysts. All the latter are cylindrical or spindle-shaped bacilli, of
similar form and equal size, three to six times as long as broad, sometimes straight, at
other times slightly curved. Their axis is perpendicular to that of the sacculus. The
convex dorsal surface of the sacculus, therefore, appears elegantly panelled or facetted,
the outer or abaxial ends of the paliform cnidocysts forming regular transverse rows
(crossing the longitudinal rows).

(ZOOL. CHALL. EXP. PART LXXVII. — 1888.) Hhllll 13

98 THE VOYAGE OF H.M.S. CHALLENGER.

The large sabre-shaped or lateral thread-cells (Cnidocysts ensiformes, kg) form
constantly two small lateral groups in the basal or proximal part of the sacculus, covering
both the right and left sides of the base, of the cnido-battery. Their number and
form are often characteristic of the individual species of Calyconectae. Thus, for
example, Mitrophyes peltifera (PL XXVIII. fig. 8) has only two, Oymbonectes huxleyi
(PI. XXVII. fig. 7) three, Diphyopsis compressa (PI. XXXIV. fig. 18) six large lateral
thread-cells on each side of the base of the sac ; their number is larger in the Abylidae
(usually eight to twelve), and especially in the Prayidae (sixteen to twenty, or more, on
each side). Their form is usually slender, spindle-shaped or sabre-shaped, four to eight
times as long as broad, straight, sometimes slightly curved ; but sometimes they are
more rounded, ovate (as in the smallest Calyconectse). They are always placed in a
single longitudinal row, parallel to one another, and also (more or less) to the axis of the
sacculus. Usually the axis of the ensiform cnidocysts is so directed obliquely that the
dorsal end is more proximal and medial, the ventral end more distal and lateral.

The small pear-shaped or distal thread- cells (Cnidocystse pyriformes, hp) always
form an odd group at the distal end of the cnidosac and touch the base of the terminal
filament (tf). Their number is very variable, usually between twenty and sixty. The
group formed by these pyriform cnidocysts has usually the form of a rounded cap,
covering the distal end of the cnido-battery, and is evidently sensitive to a remarkable
degree, since long cnidocils arise from these thread-cells. Sometimes the group is tri-
lobate, with an odd middle and two lateral lobes ; and in some species it is even divided
into three separate parts, an odd medial group being separated from two paired lateral
groups, as in Praya (PI. XXXII. figs. 12-14) and in Bassia (PI. XXXVIII. fig. 16).

The elastic angle-band, composed of two very long linear and parallel ribbands, is
closely coiled up spirally in the thin-walled ventral pouch of the closed cnidosac. But
when this becomes opened (by rupture of the thin ventral wall), then the angle-band is
expanded to a great length, often folded in a zigzag. Its proximal end remains in
connection with the pedicle (tp), its distal end with the terminal filament (tf). The
cnido-battery becomes hung out, and is freely prominent, and its distal end only re-
maining in connection with the proximal part of the terminal filament and its junction
with the elastic angle-band (PI. XL. fig. 20).

Gonophores. — The sexual persons of the Calyconectse are always quadriradial Medusae,
with a well-developed umbrella and a manubrium, in the thickened wall of which the
sexual cells are produced from the exoderm. The cavity of the manubrium has,
however, no mouth opening, and the margin of the umbrella bears no tentacles.
Originally each cormidium possesses only one gonophore, and in many Calyconectse
never more than a single sexual medusome is attached to the siphon. But when this
gonophore is mature, it usually detaches itself from the cormidium (Eudoxia) and may
be replaced by a secondary or vicarious gonophore. In many species (mainly of Abylidae)

REPORT ON THE SIPHONOPHORiE. 99

two or three gonophores are developed simultaneously in a single cormidium, and in
some genera (IAlyopsis, Desmophyes) a bunch of numerous clustered gonophores ; then
usually their umbrella is more or less rudimentary, whilst still a " special nectophore "
is developed as a swimming organ.

Each single gonophore is always gonochoristic, either male or female. Those cor-
midia, which bear two or more gonophores, are usually also gonochoristic (diclinic) ; but
in some cases they are hermaphrodite, one of the gonophores being female, the other
male (monoclinic cormidia). The corms of the polygastric Calyconectse are usually
monoecious and bear cormidia of both sexes, sometimes regularly alternating (as in
Cymbonectes, PL XXVIL, and Desmophyes, PL XXX.). At other times the distal
(older) cormidia are males, and the proximal (younger) cormidia females. A few genera
of polygastric Calyconectse are dioecious, each cormus bearing only gonophores of one
sex, either male or female (Mitrophyes, Galeolaria). But the question of the relation
of these different forms of sexual differentiation requires a further examination.

Umbrella of the Gonophores. — The calyx or umbrella of the sexual persons has in
all Calyconectse the same structure as in a common simple quadriradial Hydromedusa.
Its form is very rarely quite regular, hemispherical (as in Diplophysa and some Poly-
phyidae) ; usually it is more or less bilaterally symmetrical, in adaptation to its place
inside the bracteal cavity, at the ventral side of the siphon ; sometimes it is strongly
asymmetrical, as in Amphiroa (PL XXXVI. figs. 12-25) ; here two gonophores are
developed simultaneously on each side of the siphon (right and left) ; each corre-
sponding to an antimere, so that the two together form a symmetrical pair.

The Exumbrella of the Gonophores corresponds in its general form to a certain degree
with that of the nectophores. It' is therefore evenly convex and smooth, without pro-
minent edges, in most Sphseronectarise (Sphseronectidse, Prayidse, Hippopodidse). On
the other side, it is quadrangular, pyramidal, or prismatic, in most Cymbonectarise
(Cymbonectidaa, Diphyopsidse, Abylidae). Usually in the latter the four edges of the
exumbrella are sharp and prominent, often elegantly denticulate, and wing-like dilated in
the distal part ; their distal ends are often prominent as four strong triangular teeth over
the basal ostium of the umbrella. Often two paired dorsal edges and their terminal
teeth are much more developed than the opposite two ventral edges. More rarely a
single wing is stronger than the three others, or even five wings may be developed
instead of four (compare Amphiroa, PL XXXVI.). The uppermost part of the exum-
brella is usually prolonged into an apical horn, or a hook-shaped apophysis, which
serves for its insertion into the bracteal cavity.

The Subumbrella of the Gonophores has always a well-developed layer of ring-muscles
(iv), and, on its distal prolongation, a circular velum (v) which closes the peripheral part
of the opening of the subumbrellar cavity. Four radial canals (cr) always run in the
subumbrella from its apex, diverging to its basal ostium, where they are united, above

100 THE VOYAGE OF H.M.S. CHALLENGER.

the insertion of the velum, by a ring-canal (cc). From their apical junction arises a
peduncular canal (cp) which runs through the pedicle of the gonophore (or the apical
horn) to its insertion into the bracteal cavity and opens here into the phyllocyst.

Gonads. — The gonad, or sexual gland of each gonophore, is represented by the
manubrium, which depends from the apex of the subumbrella into its cavity. In the
mature state it usually fills about the apical half of that cavity, but in many cases the
entire cavity, and sometimes by further growth it becomes much larger than the latter,
ami is widely prominent through its distal opening (for example, in Lilyopsis, Des-
mophyes, Vogtia, PI. XXX.). Each gonad is a simple, cylindrical, ovate, or spindle-
shaped sac, and contains a central cavity, which is closed at the distal end, whilst it
opens at the proximal end into the peduncular canal. The thick wall of the cavity
consists of three different layers, outside a covering exodermal epithelium, and inside
a vibratile entodermal epithelium, which includes the cavity (spadix) ; between these is a
layer of sexual cells, which are originally derived from the exoderm. They produce
a number of large ovules (usually between twenty and forty) in the female, and in-
numerable small zoosperms in the male gonophores. The ovaria or female gonads are
usually somewhat rounded, ovate or club-shaped, colourless (PI. XXVIII. fig. 4 ;
PI. XXXIV. figs. 13, 14, &c). The spermaria or male gonads are rather elongated,
cylindrical, or fusiform, often vividly coloured (yellow, orange, red) (PI. XXVIII. fig. 6 ;
PI. XXXIV. figs. 11, 12, &c).

Ontogeny. — The development of the Calyconectse from the fertilised egg has hitherto
been very little known. The first observations were made in the spring of 1853 by
Gegenbaur in Messina.1 He observed the segmentation of the egg of Diphyes sicboldii,
and the development from it of a larva, which is a peculiarly modified medusome,
composed of a simple nectophore and a cylindrical sac-shaped larval body, which is
attached externally to the ventral side of the nectophore. In my opinion the
mouthless larval body is the original siphon, protruded through a ventral fissure of the
nectophore. From its base the primary tentacle arises afterwards. I call this larva
Calyconula.

A similar Calyconula is developed from the egg of Galeolaria aurantiaca ( = Epibulia
aurantiaca), which Metschnikoff described in 1874.2 The Calyconula of Hippopodius
gleba, described by the same author,3 exhibits still more distinctly the dislocation of the
siphon, the axis of which is perpendicular to that of its nectophore, in the subumbrellar
cavity of which it was originally placed. The remnant of the ventral fissure of the
bilateral umbrella is yet partly visible.

The Calyconula of a Monophyid (Muggiwa kochii), and its development from the egg
as well as its metamorphosis, were described in 1882 by Chun.4 This larva developed

1 7, p. 332, Taf. xvi. figs. 12-21. 2 85, p. 39, Taf. vi., vii.

3 Loc. cil, p. 46, Taf. xi. figs. 5-S. 4 86, p. 9, Taf. xvii. figs. 6, T.

REPORT ON THE SIPHONOPHORvE. 101

directly into Cucubalus eschscholtzii ( = Eudoxia eschscholtzii), the monogastric generation
of Muggisea kochii.

Scarcely different from this is the ontogeny of another Monophyid (Cymbonectes
huxleyi (PI. XXVII. figs. 8-11), which I observed in December 1881 during my residence
at Belligemma, in Ceylon. The Calyconula here presents distinctly the character of a
bilateral Medusa, through the ventral fissure of which the siphon was protruded ; its
distal end opens through the mouth rather early. Its similarity to the young Eudoxia of
the same species is interesting.

Metamorphosis. — All Calyconeetse seem to undergo a metamorphosis, since the
gastrula, developed from the fertilised egg, develops into a larva differing more or less
considerably from the adult state. But the metamorphosis of the larva is very little
known, and has been observed in a few species only. Chun, who has observed accurately
the metamorphosis of some Monophyidse and Diphyidse (86-88), holds the opinion that
the primary umbrella of the medusiform larva is always lost and replaced by a hetero-
morphous secondary umbrella. More extended researches are required to prove whether
this supposition is generally true.

Metagenesis. — The majority of Calyconeetse are subject to a regular metagenesis, two
different generations alternating regularly, as in the majority of the Anthomedusaa. The
first generation is a monogastric and sexually developed cormidium — Eudoxia or Erssea.
From its fertilised egg arises a larva, which is transformed by metamorphosis into the
second generation — Monophyid or Diphyid. Its body is a polygastric corm, the tubular
stem of which produces numerous cormidia by budding asexually. Each cormidium,
provided with a single siphon, afterwards becomes detached from the stem, and maturing
as a Eudoxid or Ersasid returns to the first generation.

Hypogenesis. — The minority of Calyconeetse develop by hypogenesis (not by
metagenesis) ; the cormidia arrive at full sexual maturity whilst sessile on the common
stem, and are not detached from the latter. There is here, therefore, no free and
independent monogastric generation ; neither free Eudoxidse nor Ersaeidse arise. The
ontogeny of these polygastric corms is in a strict sense a strophogenesis.1

The Calyconectaa which are developed by hypogenesis are the following : — All the
Polyphyidae and Desmophyidaj, some Diphyidse (Galeolaria, Lilyopsis, and Praya ?) and
several Monophyidse (Monophyes partly ?, Mitrophyes, and Cymbonectes). All the
other Calyconectae develop by metagenesis. There seem to be, however, some inter-
mediate forms of ontogeny, in some species the male gonophores becoming detached,
whilst the females remain attached to the stem, or inversely. These relations, as well as
the whole ontogeny of the Calyconeetse, require further accurate examination.

1 On the difference between metagenesis and strophogenesis, see my Generelle Morphologie, 1866, Bd. ii. pp. 104-109,
and on Hypogenesis, op. cit., p. 99.

102

THE VOYAGE OF H.M.S. CHALLENGES.

Metagenesis Calyconectarum.

Synopsis of the alternation of generations in the genera of monogastric and polygastric
Calyconectse (compare the descriptions of the individual genera and species in this
Report).

I. Monogastric Generation.

Diplophysa inermis, Ggbr., Mediterranean.
Diplophysa kollikeri, HkL, Tropical Pacific, Indian
Ocean.

? Eudoxella didyma, Hkl., Atlantic.

? Eudoxella galea, Hkl., North Atlantic.

Cucubalus eschscholtzii, Huxley, Mediterranean.
Cucubalus pyramidalis, Will, North Atlantic.
? Cucubalus cordiformis, Quoy, Tropical Pacific.

Cuboides vitreus, Quoy, Mediterranean.
Cuboides erysfallus, Hkl., North Atlantic.
Cuboides nacella, Hkl., Indian Ocean.
Cuboides vogtii, Hkl., Tropical Pacific.

Cucullus campanula, Hkl., North Mediterranean.
Cucullus gegenbauri, Hkl. ( = Eudoxia messanensis,

Ggbr.), South Mediterranean.

Cucullus subtilis, Hkl., Mediterranean.

? Cucullus elongatus, Hkl., North Atlantic.

Cucullus lessoni, Lesson, Pacific.

Cucullus gracilis, Hkl., Indian Ocean.

Amphiroa trigona, Hkl, Mediterranean.

Amphiroa carina, Hkl., Tropical Atlantic.
? Amphiroa alata, Huxley, Indian and Pacific Ocean.
I Amphiroa angulata, Huxley, South Pacific.

Sphenoides tetragona, Hkl., Indian Ocean.
Sphenoides obeliscus, HkL, North Atlantic.
? Sphenoides perforata, Hkl., Tropical Atlantic.
Sphenoides australis, Huxley, South Pacific.

Aglaisma eschscholtzii, Huxley, Mediterranean.
Agldisma gegenbauri, Hid., Tropical and Subtropical
Atlantic.
? Aglaisma elongata, Huxley, Tropical Pacific.

1 Erssta gaimardi, Esch, Mediterranean.
Erssea compressa, Hkl., Tropical Atlantic.
Erssea dispar, Hkl., Tropical Pacific.

II. Polygastric Generation.

Spheerunectes gracilis, Hkl., Mediterranean.
Sphwonedes kollikeri, Huxley, Tropical Pacific,
Indian Ocean.

? Praya eymbiformis, Leuck., Atlantic.
? Praya galea, Hkl., North Atlantic.

MuggUea kochii, Chun, Mediterranean.
Muggixa pyramidalis, Busch, North Atlantic.
? Muggista chamissonis, Hkl., Tropical Pacific.

Cymba enneagonum, Esch., Mediterranean.
Cymba crystallus, Hkl., North Atlantic.
Cymba nacella, Lesson, Indian Ocean.
Cymba vogtii, Hkl.. Tropical Pacific.

. Diphyes acuminata, Leuck., North Mediterranean.

Diphyes sieboldii, Koll. ( = Diphyes gracilis, Ggbr.),
South Mediterranean.

Diphyes subtilis, Chun, Mediterranean.
? Diphyes elongata, Hyndman, North Atlantic.

Diphyes appendicidata, Esch., Pacific.

Diphyes gracilis, Hkl., Indian Ocean.

Abyla trigona, Quoy, Mediterranean.

Abyla carina, Hkl., Tropical Atlantic.
? Abyla alata, Hkl., Indian and Pacific Ocean.
f Abyla. leuckarti, Huxley, South Pacific.

Bassia tetragona, Hkl., Indian Ocean.
Bassia obeliscus, Hkl., North Atlantic.
? Bassia perforata, L. Ag., Tropical Atlantic.
Bassia quadrilatera, Quoy, South Pacific.

Calpe pentagona, Quoy, Mediterranean.
Calpe gegenbauri, Hkl., Tropical and Subtropical
Atlantic.
? Calpe huxleyi, Hkl., Tropical Pacific.

? Diphyopsis campcmuliferd, Hkl., Mediterranean.
Diphyopsis compressa, Hkl., Tropical Atlantic.
Diphyopsis dispar, Hkl., Tropical Pacific.

? Lilaa medusina, Hkl., Indian Ocean.

? Lilyopsis medusina, Hkl., Indian Ocean.

REPORT ON THE SIPHONOPHOR^E.

10J

Synopsis of the Families of Calyconectse.

I. Suborder

Calyconect-e monogastric^:.

Cormus represented by a siDgle corinidium, with a single
siphon and a single tentacle.

Cormidium composed of
two medusomes,a sterile
and a fertile, without
special nectophore,

Cormidium composed of
three medusomes, a
sterile, a fertile, and a
special nectophore,

II. Suborder

Calyconect^: polygastric/e.

Cormus represented by a long
tubular stem, which bears <
numerous ordinate cormidia,
separated by free internodia;
each cormidium with a siphon
and a tentacle.

One or two nectophores I A single nectophore,
on the top of the <
stem. ( Two nectophores, .

A biseiial nectosome on
the top of the stem,
composed of four to
ei"ht or more necto-

phores,
pairs.

opposite in

Each cormidium with a
bract, . .

Cormidia without bracts, .

4. Eudoxida?.

5. Ersseidse.

6. Monophyida?.

7. Diphyidse.

8. Desmophyida?.

9. Polyphyids.

Family IV. Eudoxida, Haeckel, U

Eudoxida;, Hkl., System der Siphonophoren, 95, p. 32.

Definition. — Calyconectse monogastricse, representing a single cormidium, which is
composed originally of two persons ; a sterile medusome (siphon with tentacle and bract)
and a fertile medusiform gonophore (male or female).

The family Eudoxida? comprises those monogastric Calyconectse which present in the
fully developed and sexually .mature state only a single cormidium, composed of two
different medusomes, a sterile and a fertile. The sterile medusome is a bilateral medusoid
person with three essential and constant organs, a bract (umbrella), a siphon (manubrium),
and a tentacle (capturing filament). The fertile medusome is a gonophore with umbrella
and manubrium, but without tentacles ; the sexual cells are produced in the wall of the
mouth less manubrium.

Eschscholtz (1, p. 124) in his System of the Diphyidaa, distinguished first two main
groups in this family — I. Monogastricse (" with a single suctorial tube "), Eudoxia,
Ers&a, Aglaisma ; and II. Polygastricee (" with a long digestive tube bearing numerous
suctorial tubes or lateral branches"), Abyla, Cymba, Dij)hyes.

Lesson (3, p. 437), adopting the division of Eschscholtz, and collecting the descriptions
of other observers (mainly Quoy and Gaimard, 2 and 20), described a greater number of
"Diphyidaj monogastricae," with not less than nine genera (Joe. cit., pp. 453-462).
Some other species were described by Will (65) and Busch (67).

The true nature of the monogastric Diphyidse (called usually Eudoxise. sensu ampliori)
was not recognised before 1853. In the spring of that year Gegenbaur discovered that

104 THE VOYAGE OF H.M.S. CHALLENGER.

the cormidia of Abyla penfagona, detached from the common stem, live independently
and develop into a sexual Eudoxia.1 Leuckart, who had made the same observation
simultaneously, demonstrated further that the monogastric Eudoxia campanula is
nothing more than the detached cormidium of the polygastric Diphyes acuminata
(5, pp. 41, 69 ; 8, pp. 268, 277).

Huxley, in his excellent description of Diphyidse, separated the monogastric forms or
Eudoxias under the title " Diphyozooids." 2 He pointed out, with full reason, that it is
necessary on practical grounds to retain generic and specific names for the single
Diphyozooids, though they may possibly be only detached and independent portions of
" Polygastric Diphyidse." He gave a full anatomical description of many new or imper-
fectly known Eudoxise, and comparing their structure with that of the sessile cormidia of
corresponding polygastric Diphyidse, he suspected an ontogenetic connection between
these two forms (op. cit., 1859).

During my residence in the Canary Island, Lanzerote (in the winter of 1866-67), I
had occasion to examine nearly all the interesting genera of Diphyozooids which Huxley
had accurately described. I was able to confirm most of his suppositions concerning
their connection with certain polygastric Diphyidse, observing directly the development
and detachment of the former from the latter (compare above, pp. 101, 102).

The metagenesis which connects the monogastric and polygastric Diphyidse is
usually combined with a peculiar metamorphosis, some interesting cases of which have
recently been described by Chun (86-88).

The detached and independent cormidia of Calyconectse — of the " Diphyozooids " —
arise in two different main-forms, Eudoxia and Erssea, which we regard here as repre-
senting two different families, Eudoxidse and Ersaeidas. Each Eudoxia is composed of
two medusoid persons, a sterile medusome (bract with siphon and tentacle) and a fertile
medusome (gonophore). Erssea differs from Eudoxia in the possession of a sterile " special
nectophore," and is therefore composed of three medusomes.

The sterile medusome has in all Eudoxidse the same characteristic composition of three
essential parts — a bract (covering scale or hydrophyllium), a siphon placed in the dorsal
part of the bracteal cavity, and a tentacle attached to the base of the siphon. The fertile
medusome, or the gonophore, occupies the ventral part of the bracteal cavity.

Bract or Hydrophyllium. — The protectum or bract of each Eudoxia ("Deckstiick or
Deckblatt " of German authors) is the modified umbrella of the sterile medusome. This
is very obvious in the genera Eudoxella (PL XXXII.) and Aglaisma (PI. XL.), where the
four radial canals of the subumbrella are preserved by heredity, whilst its muscle-plate is
lost by adaptation ; furthermore, the jelly cap is strongly developed, forming a thick and
firm protecting shield or cap (" covering scale ").

Regarding the characteristic form of the bract, I distinguish two subfamilies among

1 4, p. 78 ; 7, p. 205, Taf. xvi. figs. 1, 2. - 9, pp. 57-66, pis. iii.-v.

REPORT ON THE SIPHOTSTOPHOR^E. 105

the Eudoxidaa. The first group, Diplophysidse, possess a smooth umbrella with rounded
surface, never prismatic; hemispherical or mitriform in Diplophysa and Eudoxella, conical
or spathiform in Cucubcdus and Cucullus. The second subfamily, Aglaismidae, has a poly-
hedral or prismatic umbrella with angular surface ; it is more or less cuboidal in Cuboides
and Af/laisma, wedge-shaped or similar to a prompter's box in Sphenoides and Amphiroa.
The cuboidal form (Pis. XL., XLII.) is of special interest as a reminiscence of the quadri-
radial structure in the orisjmal umbrella of the ancestral Medusa.

Bracteal Cavity. — Whilst the superior or proximal face of the bract is convex, and
corresponds to the exumbrella of the Medusa, its inferior or distal face is concave and
comparable to the subumbrella. In the fundus of this cavity hangs the siphon, like the
manubrium or gastral tube of the Medusa. Its point of insertion is usually dislocated
towards the dorsal side. The single tentacle, which arises from the base of the siphon,
is placed between this and the dorsal wall of the subumbrellar cavity. The greater
ventral part of the cavity is occupied by the gonophore.

The form of the bracteal cavity has sometimes preserved the original hemispherical
form of the subumbrella ; but usually it is more campanulate or conical, and often at the
same time bilateral, more rarely asymmetrical. Its basal opening, or the bracteal mouth,
is usually oblique, more or less bevelled off, sometimes armed with prominent teeth.

Phyllocyst.- — The central part of the subumbrella, where the siphon is inserted, con-
tains in each Eudoxia a caecal diverticulum of the entoderm, which is in direct communi-
cation with the basal part of the siphon, and in the young sessile Eudoxia with the
central canal of the stem. This phyllocyst (bursa centralis bractese) is comparable to the
apical canal, which in certain Medusae (Codonidae, &c.) ascends vertically from the base
of the manubrium, and ends blindly in the jelly of the umbrella.

The cavity of the phyllocyst is usually small, lined by large clear vacuolated entoderm-
cells, which are polyhedral from mutual pressure. The apical part of the phyllocyst usually
contains an oleocyst (co), an oil-globule, which has a hydrostatic function. The phyllocyst
of the bract is, therefore, similar to and comparable with the somatocyst of the nectophore.

The phyllocyst is sometimes a simple cylindrical caecal canal or an ovate sac, placed
in the vertical axis of the bract, or somewhat excentric ; as in Diplophysa, Cucubalus,
and Cucullus. But usually some nutritive canals arise from its base, which enter into
the jelly mass of the bract. The number and disposition of these phyllocyst canals are
characteristic of the different genera, and of interest as remnants of the four radial canals,
which run in the subumbrella of Medusae towards its margin. Eudoxella (PL XXXII.)
and Aglaisma (PL XL.) still possess all four canals ; two of them are placed in the sagittal
plane (one dorsal and one ventral), two others symmetrically on both sides (one right
and one left). The latter are preserved too in Cuboides (PL XLII.) and in Amphiroa (PL
XXXVI.), whilst the two sagittal canak are lost. Sphenoides (PL XXXVIII.) possesses
only a single canal, descending on the dorsal side ; the three others have disappeared.

(ZOOL. OHALL. EXP. PART LXXVII. — 1888.) Hhhh 14

106 THE VOYAGE OF H.M.S. CHALLENGER.

Siphon. — The single polypite of Eudoxia, or the manubrium of the sterile medusome,
always exhibits the same structure as in other Calyconectse. It is composed of four con-
stant parts: — (1) A short pedicle (sp) ; (2) a thick-walled, usually hemispherical, basi-
gaster, with masses of cnidoblasts (sb) ; (3) a dilated stomach, separated from the latter
by a pyloric valve, and usually provided with liver-stripes (sm) ; and (4) a very extensile
and contractile proboscis ; the latter opens through the mouth, which often exhibits four
or eight lobes. (Compare PL XXXII. fig. 8; PL XXXIV. figs. 9-11 ; PL XXXVIII.
fig. 12 ; PL XL. figs. 13, 14, &c.)

Tentacles. — The single tentacle, which arises in each Eudoxia from the pedicle of the
siphon, has usually the structure which is characteristic of the alyconectse. The long
cylindrical and very contractile tubule is beset with numerous lateral branches or
tentilla, separated by equal intervals. Each tentillum is composed of three parts, a
slender pedicle, a reniform or ovate cnidosac, and a slender terminal filament. On the
structure of the cnidosac compare above, p. 97.

Gonophores. — Each Eudoxia produces originally only a single gonophore, and this
fertile medusome is placed in the ventral part of the bracteal cavity of the sterile
medusome, before its siphon. In many species there is constantly found only a single
gonophore, and when this becomes detached, it is usually soon replaced by a secondary
or vicarious gonophore ("Ersatz-Geschlechts-Glocke"). But in some species usually two,
or even three, gonophores are found at the same time developing in one bracteal cavity ;
they are usually of different sizes and ages, one placed at the right of the siphon, the
other at its left (Pis. XXXIV, XLIL).

EudoxiaB with a single gonophore are always gonochoristic, either male or female.
When, however, two or three gonophores are developed simultaneously, then they are
either of the same sex (Eudoxiie diclinicse, PL XLIL figs. 10, 14) or of different sexes
{Eudoxise monoclinicse, PL XL. fig. 14).

Each single mature gonophore of the Eudoxidse is a well-developed quadriradiate
Medusa, without mouth and tentacles, with sexual cells in the wall of the manubrium
(spadix). The umbrella is rarely rounded, and without sharp edges, as in the gonophores
of Dip>lophysa aaA Eudoxella; usually it is four-edged, prismatic or pyramidal ; commonly
two dorsal edges are more strongly developed, and more prominent over the basal ostium,
than the two ventral edges. The apex of the umbrella is always prolonged into a beak-
shaped apophysis or apical horn, the pedicle by which the gonophore is attached to the
bracteal cavity. The quadriradial form of the umbrella in the single gonophore is
usually symmetrical (with equal right and left halves) ; but when two gonophores are
placed symmetrically on the two sides of one siphon, they are often modified by mutual
pressure, and the single umbrella assumes an asymmetrical (sometimes pentagonal) form.
(Compare p. 115, and PL XXXVI. figs. 12-25.)

Compare on the development of the Eudoxidas above, pp. 100-102.

REPORT ON THE SIPHONOPHOR^E.

107

Synopsis of the Genera of Eudoxidse.

I. Subfamily

Diplophtsidj;.

Bracts not polyhedral, never
prismatic, without com-
plete sharp edges and poly-
gonal faces. (Exumbrella
rounded and smooth, not
facetted.)

Bract hemispherical or mitri-
forra, rounded, without
sharp edges, and without
pointed apex.

' Phyllocyst simple,
radial canals,

without

II. Subfamily

Aglaismid.e.

Bracts polyhedral, more or ,
less prismatic, with many '
sharp edges and polygonal
faces. (Exumbrella facet-
ted and angular.)

Bract conical, spathiform or
pyramidal, with a pointed ,
apex, and often with some '
incomplete edges.

Bract more or less cuboidal,
with an inferior opening
into its cavity at the basal
face.

Bract not cuboidal, with an
anterior opening into its
cavity at the obliquely
bevelled ventral face.

Phyllocyst with four radial
canals arising from its
base, ....

Phyllocyst simple. Bracteal
exumbrella smooth, with
no sharp edge, .

Phyllocyst simple. Bracteal
exumbrella with three or
five edges,

Phyllocyst with two lobate
lateral canals. Bract with-
out caudal apophysis,

Phyllocyst with four cruciate
radial canals. Bract with
a pyramidal caudal apo-
physis, .

Phyllocyst descending, with
two superior lateral canals.
Bract with five odd trape-
zoidal and two paired
pentagonal faces,

Phyllocyst ascending, with an
odd inferior canal. Bract
with four odd and four
paired faces,

10. Diplophysa.

11a. Ewloxella.

11b. Cucubalus.

12. Cucullus.

13. Cuboides.

16. Aglaisma.

14. Amphiroa.

15. Sphenoides.

Genus 10. Diphphysa,1 Gegenbaur, 1854.
Diplophysa, Ggbr., Zeitschr. f. wiss. Zool., Bd. v. p. 291.

Definition. — Eudoxidae with a hemispherical or subspherical bract, without sharp
edges, in the vertical axis of which is placed a simple ovate or cylindrical phyllocyst.
(Eudoxise of the genus Sphieronectes.)

The genus Diplophysa comprises those monogastric Eudoxidse which arise from the
polygastric Monophyid genus Sphieronectes (Genus 18). It was founded in 1854 by
Gegenbaur for a Mediterranean Eudoxia, distinguished by a subspherical bract with a
simple phyllocyst.2 It is very similar to another Mediterranean species, described in
1844 by Will under the name Erssea truncataJ Thirty years later Claus (70) demon-

1 Diplophysa = Double vesicle, Bi's-Xoa, Qiao.. - 7, p. 291, Taf. xvi. fig. :!.

3 65, p. 82, Taf. ii. fig. "28.

108 THE VOYAGE OF H.M.S. CHALLENGER.

strated that this monogastric Calyconecta is the detached free Eudoxia of a polygastric
Monophyid, which was first described in 1859 by Huxley as Sphaeronectes kolliheri
(9, p. 50). He called it Monophyes gracilis (compare below the descriptions of Genera 18
and 19). The peculiar metagenesis of these two forms of Calycophorida? was afterwards
accurately described by Chun (86, 87).

A few Eudoxia? of this genus were found by me in a bottle in the Challenger collec-
tion, taken in the Tropical Pacific, Station 274. Since the same bottle contained a
specimen of Sphseronectes kolliheri, it is probable that they were detached from the
latter. I call them Diplophysa kolliheri.

Diplophysa differs from all other Eudoxidse in the hemispherical, or nearly spherical,
form of its bract, and the simple ovate or cylindrical shape of its phyllocyst, which
ascends vertically in the axis of the bract. In the centre of the shallow subumbral
cavity of the bract is suspended a hemispherical gonophore, of about the same size, and
between these two, at the ventral face of the latter, is a simple siphon with its tentacle.

Genus 11a. Eudoxella,1 Haeckel, 1888.

Eudoxella, Hkl., System der Siphonophoren, p. 32.

Definition.— Eudoxidae with a mitriform, helmet-shaped, or hemispherical bract, the
exurnbrella of which is smooth and without sharp edges. Phyllocyst with four radial
canals arising from its base. (Eudoxia? of the genus Praya ?)

The genus Eudoxella, as defined in my System, comprises free Eudoxise, the bract of
which is essentially identical with that of the sessile cormidia of Praya (PL XXXIL).
1 suspect, therefore, that this genus is the monogastric generation of a true polygastric
Praya. But the well-known species of this latter (Praya galea, Praya maxima,
Praya cynibiformis) are generally assumed to possess eudoxomes, which become mature
whilst still attached to the common stem. The question, however, whether this holds
good as a general rule, requires further accurate examination.

A bottle in the Challenger collection, containing surface animals taken in the Tropical
Atlantic (Station 343, April 10, 1876), contained a few specimens of a Eudoxella, which
is very similar to the sessile eudoxome of Praya galea (PI. XXXIL). But the helmet-
shaped bract was more highly vaulted, and the four radial canals, arising from the base
of the phyllocyst, were shorter and more equally disposed. The main difference was
indicated by the remarkable fact, that each Eudoxia exhibited no trace of the stem of a
Praya, and contained a large, completely mature gonophore. It is therefore probable
that this Eudoxia, which I call Eudoxella didyma, may be the detached cormidium of
some unknown species of Praya (Praya cymbiformisf), the gonophores of which are not
brought to maturity whilst sessile on the stem.

1 Eudoxella^- Small Eudoxia.

REPORT ON THE SIPHONOPHOR^E. 109

Genus 11b. Cucubalus,1 Quoy et Gaimard, 1824 (MS.).
Cucubalus, Blainville, Manuel d'Actinologie, 1834, p. 130.

Definition. — Eudoxidse with a conical, spathiform or cordiform bract, obliquely
bevelled on the ventral side, evenly convex on the smooth dorsal side, pointed at the
apex. Phyllocyst simple, ovate. (Eudoxise of the genus Muggisea.)

The genus Cucubalus was founded by Quoy and Gaimard (2. pi. iv. figs. 24, 27) upon
a Eudoxia from the Tropical Pacific, which Blainville afterwards described as Cucubalus
cordiformis (24, p. 130). It may be, perhaps, the monogastric generation of Muggisea
chamissonis ( = Diplujes chamissonis, Huxley, 9, pi. i. fig. 3). The best known
representative of the genus is the Mediterranean Cucubalus eschscholtzii, which was
described by Busch as Eudoxia eschscholtzii.2 Its development from the polygastric
Muggisea kochii, and the regular metagenesis of these two forms, were afterwards
described very accurately by Chun (86, 87). A similar and nearly allied species
was observed by me in 1866 in the Canary Island, Lanzerote, and I found it again in
some bottles from the Challenger collection taken in the Tropical Atlantic (Stations
348, 352). This Atlantic species may retain the name of Cucubalus pyramidalis, and
its polygastric generation Muggi&a pyramidalis, with respect to the original names of
Busch and Will (compare Chun, 85).

The genus Cucubalus is closely allied to the following Cucullus, the monogastric
generation of Diphyes. It differs from the latter in the smooth and edgeless shape of
the bract, which is more rounded and not pyramidal.

Genus 12. Cucidlus,3 Quoy et Gaimard, 1824 (MS.).

Cucullus, Blainville, Manuel d'Actinologie, 1834, p. 131.

Definition. — Eudoxidse with a cowled or cucullate, sometimes three-sided pyramidal
bract, open at the bevelled ventral side, evenly convex, or sometimes with three incom-
plete edges on the dorsal side, pointed at the apex. Phyllocyst simple and conical.
(Eiidoxige of the genus Diphyes.)

The genus Cucullus contains those monogastric Eudoxidaa which arise from the
polygastric genus Diphyes, in the restricted sense in which recent authors have employed
it, and which we have accepted. The bract is irregularly conical, or pyramidal, with
a deep ventral fissure, which passes into the obliquely truncated cavity. Its dorsal face
is either evenly convex, or slightly three-sided, its apex pointed. The inferior half
of the spathiform bract embraces the included siphon and gonophore like a mantle, and

1 Ci«:w&aZMS= Name of a plant. ! 67, p. 33, Taf. iv. figs. 7-10 ; and Taf. v. figs. 1-9.

3 Cucullus = Cowl.

110 THE VOYAGE OF H.M.S. CHALLENGER.

often one of its free ventral margins overlaps the other ; the superior half is comparable
to the cowl of the mantle, and includes the simple ovate ascending phollocyst. The free
inferior part of the mantledobes often exhibits two small prominent teeth.

The genus Cucullus was founded by Quoy and Gaimard upon an Australian Eudoxia,
which they figured first under the name Diphyes cucullus (2, p. 92), synonymous with
Eudoxia lessonii of Eschscholtz (1, p. 126). Blainvdle called the former in 1834
Cucullus doreyanus (24, p. 131), and Lesson himself separated the latter as Cucullus
lessonii (3, p. 459). Indeed the genus Cucullus of the French authors (published
in 1834) is identical with Eudoxia of Eschscholtz (1829). But since Gegenbaur
and Leuckart, in 1853, demonstrated that the Eudoxise are the isolated cormidia of
Diphyidse, the term Eudoxia is generally used for all these " Diphyozooids " (Huxley,
1859, 9, p. 57). It seems, therefore, best, to avoid further confusion — to employ the
term Cucullus for the monogastric generation of those Diphyidas which constitute the
genus Diphyes in the strictest sense (compare below, Genus 27). The typical and
oldest species remains Cucullus lessoni, as the free Eudoxia of the Pacific Diphyes
appendiculata, Esch.

Scarcely different from Cucullus is the genus Cucubalus of Quoy and Gaimard.
This genus, however, maybe retained for the Eudoxise of theMonophyid Muggisea, which
are very similar to those of Diphyes. (Compare the preceding genus.)

Many bottles of surface animals in the Challenger collection contained specimens of
Eudoxise belonging to Cucullus, and in some cases it was possible to demonstrate their
connection with a species of Diphyes contained in the same bottle as the former.
Supported by the comparative study of these forms, and of similar forms compared in
other collections, and partly observed living by n^self, I have been led to state the
ontogenetic connection of the following species of monogastric Cucullus with corre-
sponding species of polygastric Diphyes : —

1. CucidJus lessoni, Lesson (3, p. 459), synonymous with Eudoxia lessonii,

Eschscholtz (1, p. 126), is the free Eudoxia of Diphyes appendiculata,
Esch. (1, p. 138), taken in the Pacific.

2. -Cucullus gracilis, Hkl., synonymous with Eudoxia bojani, Esch. (1, p. 125)

and Huxley (9, p. 59), is the free Eudoxia of Diphyes gracilis, Hkl.,
taken in the Southern Pacific and in the Indian Ocean.

3. Cucullus elongatus, Hkl., is the free Eudoxia of Diphyes elongata, Hyndman

(64, p. 166), occurring in different parts of the Northern Atlantic, Gulf
Stream, &c.

4. Cucullus gegenhauri, Hkl., synonymous with Eudoxia messanensis, Ggbr.

(7, Taf. xvi. fig. 4), is the free Eudoxia of Diphyes sieboldii, Koll.
(4, Taf. xi.), Mediterranean and Tropical Atlantic.

REPORT ON THE SIPHONOPHOR^E. Ill

5. Cucullus campanula, Hkl., synonymous with Eudoxia campanula, Leuckart

(5, p. 43), is the free Eudoxia of Diphyes acuminata, Leuck. (5, Taf. iii.),
inhabitant of the Mediterranean.

6. Cucullus subtilis, Hkl., synonymous with Ers&a elongata, Will (65, p, 82,

Taf. ii. fig. 30), is the free Eudoxia of Diphyes subtilis, Chun (88, p. 687),
also Mediterranean.

Genus 13. Cuboides,1 Quoy et Gaimard, 1827.
Cuboides, Quoy et Gaimard, Ann. d. Sci. Nat. (Zool.), t. x. p. 19.

Definition. — Eudoxidse with a cuboidal bract, bounded by six quadrangular faces,
twelve edges, and eight angles. Phyllocyst composed of a slender vertical canal, and
two broad horizontal lateral lobes at its base. (Eudoxise of the genus Cymba.)

The genus Cuboides (PI. XLII.) comprises those very remarkable monogastric
Eudoxidas, which arise from the polygastric Monophyid genus Cymba (Genus 23, PL
XLL). Its bract has the extraordinary form of a subregular cube, and is distinguished
by a very characteristic phyllocyst. This is composed of a slender, vertically ascending
canal, which usually includes an oleocyst ; and a wide basal diverticulum, which is
divided into two broad, horizontally diverging, and ventrally directed lobes. We may
compare these latter with the two symmetrical lateral canals of a bilateral Medusa,
wlrilst the ascending canal corresponds to the odd ventral vessel. The fourth, dorsal and
descending canal (preserved in Aglaisma) is lost in Cuboides. The basal diverticulum
of the latter is the proper phyllocyst.

The genus Cuboides was founded by Quoy and Gaimard (loc. cit.) upon an isolated
Eudoxia, found in the Straits of Gibraltar, and called Cuboides vitreus. This is probably
the detached monogastric form of the polygastric Cymba enneagonum found by the French
authors at the same locality. It seems different from the species occurring in the Eastern
Tropical Atlantic, and figured by me in PL XLII. as Cuboides crystallus. The figures
and descriptions of the French authors are too insufficient to identify the two forms. The
first accurate description of this peculiar Eudoxia, its cuboidal hydrophyllium and bilobed
phyllocyst, was given in 1859, by Huxley (9, p. 63, pi. iv. fig. 5). He took it twice,
once on the east coast of Australia, and once on the south coast of New Guinea, called
it Cuboides vitreus, and suspected, rightly, that it might be derived from his Abyla
vogtii [loc. cit., pi. ii. fig. 3). Different from this Australian species is an Indian
species (Cuboides nacella, Hkl.), and the Atlantic species, which I shall describe in the
sequel. It occurred in a bottle of the Challenger collection, from Station 352, near the
Cape Verde Islands. I myself examined this species living in the Canary Islands in
February 1867, and observed directly its origin and detachment from the polygastric
Monophyid Cymba crystallus (compare below, Genus 23).

1 Cuboides — Cuboidal, xvpou ant.

112 THE VOYAGE OF H.M.S. CHALLENGES.

Cuboides crystallus, n. sp. (PI. XLIL).

Habitat. — Tropical and Subtropical Atlantic, Station, 352; lat.' 10 °55' N., long.
17°46'W. Surface.

Canary Islands, Lanzerote, February 1867 (Haeckel).

Bract (fig. 9, u, lateral view from the right side; fig. 10, u, dorsal view; fig. 13, u, basal
view ; fig. 14, w, apical view ; figs. 11, 12, a younger specimen, seen from the left and
from the dorsal sides respectively). — The hydrophyllium or bract is very large (10 to
12 mm. diameter), nearly cuboidal, with six flattened, slightly concave, quadrangular faces,
twelve serrate, slightly concave edges, and eight prominent, three-sided pyramidal
angles. The six faces are of nearly equal size, the apical face (ua) somewhat smaller,
and the basal face a little larger than the four lateral faces (ud, dorsal ; uv, ventral ; ux,
right ; id, left). The basal, inferior or distal face is occupied by a wide, flatly conical,
subumbrellar cavity (ui), its apex reaches the centre of the cube.

Phyllocyst (cs). — The apical canal of the bract, or the phyllocyst, consists of two
very different parts, the axes of which are nearly perpendicular one to another. The
slender apical part is subvertical, spindle-shaped, includes a fusiform oleocyst (co)', and
touches with its apex the centre of the concave apical face of the bract (ua). The
dilated basal part of the phyllocyst, however, is divided into two broad ovate horizontal
lobes (cs", right ; cs', left) ; these are filled up with large clear entoderm cells, directed
towards the ventral face of the bract (uv), and embrace the uppermost part of the
peduncle of the siphon' (s).

Siphon (s). — The siphon or polypite is pyriform, very contractile, suspended in the
top of the subumbrellar cavity, and exhibits a pale yellowish colour. Its short pedicle
bears at its thickened base, on its dorsal side, the tentacle (t) ; on its ventral side are
placed one or two gonophores (g).

Tentacle (t). — The single tentacle of this cuboidal Eudoxia is usually coiled up and
hidden in the dorsal part of the infundibular cavity, behind the siphon. The tentilla or
secondary filaments (fig. 16) have a thin pedicle (ts) and a simple terminal filament (tf),
and between them a large reniform sacculus. This cnidosac has a leather-yellow or
reddish-yellow colour, and contains on the convex dorsal side numerous (six to nine)
rows of medial cnidocysts (km), and on each side of this battery, in the proximal part, a
series of six to nine very large, spindle-shaped, lateral cnidocysts (kg) ; at the distal end
a small group of small pyriform cnidocysts.

Gonophores. — The Eudoxise develop in the bracteal cavity, on the ventral side
of the siphon, either male or female gonophores. The young Eudoxise (figs. 11, 12)
exhibit only one gonophore, the older two or three (figs. 9, 10, 13, 14). The umbrella of
the gonophores (or the gonoealyx) is quadrangular, slightly bilateral, a little asymmetrical.

REPORT ON THE SIPHONOPHOK-ffi. 113

Its superior or proximal half has four smooth edges, is pyramidal, and forms a prominent
ventral crest. Its inferior or distal part is a quadrilateral prism with four strong serrate
edges, prominent below as four three-sided pyramidal apophyses, the two dorsal far
larger than the two ventral (fig. 1 1 ).

Canal of the Gonophores (fig. 17, cp). — This is long, peduncular, and divides at the
apex of the subumbrella («>) into four rather regular radial canals (or). These exhibit an
elegantly pinnulated appearance, produced by alternately prominent small diverticula.
They are connected at the base of the large velum (v) by a circular canal (cc).

The ovaria (fig. 17, o), as well as the spermaria (figs. 9-14, km), are spindle-shaped
manubria, which hang freely in the upper half of the umbrellar cavity of the gonophores.
They contain a large central cavity (spadix).

Genus 14. Amphiroa,1 Blainville, 1834.
Amphiroa, Blainville, Manuel d'Actinologie, p. 133.

Definition. — Eudoxidse with a bilateral, prismatic bract, bounded by five odd trape-
zoidal faces and two paired pentagonal faces. Phyllocyst composed of an ovate de-
scending dorsal sac, and two slender horizontally diverging lateral canals at its apex.
(Eudoxise of the genus Abyla.)

The genus Amphiroa (PL XXXY1.) comprises those monogastric Eudoxidse which
arise from the polygastric Diphyid genus Ahyla (Genus 29, PL XXXV.). Its bract has
a peculiar and very complicated form, which may best be compared with a prompter's box.
It is composed of two four-sided prisms, which are united at right angles. The vertical
prism covers the dorsal side of the Eudoxia, and is nearly filled up by a very large sac-
shaped phyllocyst. From the apex of the latter arise two divergent lateral canals which
run horizontally in the second prism, covering the apical face of the Eudoxia.

The genus Amphiroa was first observed and named by Lesueur (probably in 1803),
but first published from his drawings by Blainville, in 1834."' A very accurate description
of it was given in 1859 by two excellent observers, Huxley (9, p. 64) and Gegenbaur
(10, p. 17). These two authors, independently of each other, arrived at the same
opinion, that Amphiroa is the free Eudoxia of Abyla triyona. The latter, therefore,
called it Eudoxia trigones. We retain this name for the Mediterranean species, whilst
Amphiroa. alata of Huxley is the Eudoxia of Abyla alata, inhabiting the Tropical
Pacific and Indian Ocean. A third species, described by Huxley as Amphiroa angulata
(9, pi. v. fig. 2), is probably the Eudoxia of Abyla leucharti, Huxley. Different from
these three species is Amphiroa carina, which occurred in a bottle in the Challenger
collection, taken at Station 348. I myself observed this species living, and detaching
itself from Abyla carina, in February 1867, in the Canary Islands.

1 Amphiroa, ' ApQiQu, a daughter of Okeanos. - 24, p. 133, Atlas, pL iv. tig. 1.

(ZOOL. CHALL. EXP.--PART LXXV1I. — 1888.) Hhhll 15

114 THE VOYAGE OF H.M.S. CHALLENGER.

Amphiroa carina, n. sp. (PL XXXVL).

Habitat. — Tropical and Subtropical Atlantic, Station 348 ; April 9, 1876 ; lat. 3° 10'
N., lone. 14° 51' W. Surface.

Canary Islands, Lanzerote, February 1867 (Haeckel).

Bract (figs. 14, llJ, and 21, ventral view; fig. 15, dorsal view ; fig. 16, apical view;
figs. 17 and 20, basal view; figs. 13 and 18, lateral view from the left side; fig. 12,
lateral view from the right side. Figs. 12 and 13 taken from immature Eudoxomes,
sessile on the stem). —The bract or hydrophy Ilium has a diameter of 6 to 8 mm.,
and in general the form of a prompter's box ; it may be described as a bilateral poly-
hedron, which is composed of two four-sided prisms united perpendicularly ; the superior
or horizontal prism includes the two diverging horizontal phyllocyst canals ; the posterior
or vertical prism includes the large vertically depending phyllocyst. The obliquely
bevelled ventral face of the bract (the inferior face of the first, and the anterior face of
the second prism) is deeply excavated, and encloses the siphon and the gonophores.

The horizontal apical or superior face (fig. 16) is trapezoidal, the ventral edge three
times as long as the parallel dorsal edge ; the two equal lateral edges are concave, as
long as the former, and diverge ventrally.

The vertical dorsal or posterior face (fig. 15, ud), through which the phyllocyst (be)
shines, is also trapezoidal, the basal edge twice as long as the parallel apical edge and half
as long as the two lateral edges, which are slightly concave, and diverge towards the
base.

The two lateral faces of the bract (figs. 12, 18, between ventral and dorsal faces) are
concave, irregularly pentagonal, nearly vertical, and divergent from the dorsal to the
ventral side. The superior horizontal and the posterior vertical edge of the pentagon
are the longest, of nearly equal size, and meet at right angles (in the apical corner of the
dorsal face). The vertical anterior and the horizontal inferior edge are only half as long-
as the former. The ventral (or antero-basal) edge of the pentagon, between the anterior
and inferior edges, is deeply emarginate and serrate.

The horizontal basal or inferior face of the bract (fig. 17, ub) is nearly square, and the
smallest of all its six faces. Its ventral edge is bisected by the prominent median groove
of the bract-cavity.

The ventral or anterior face of the bract (figs. 14, 21) has the most complicated form
of all six faces, and is deeply excavated by the cavity which includes the siphon and the
gonophores. The ventral opening of this cavity has again a trapezoidal outline ; its upper
horizontal edge is three times as long as the parallel basal edge, and somewhat longer
than the two dentate lateral edges which diverge upwards. The superior part of the
ventral face, above the opening of the cavity, is formed by a broad frontal face through

REPORT ON THE SIPHONOPHOR^E. 115

which the two phyllocyst-cauals shine. This facet is nearly rectangular, its horizontal
inferior edge somewhat longer than the parallel superior, and three times as long as the
two short lateral edges which diverge downwards.

The bract of the young Eudoxomes, sessile on the stem (fig. 13), exhibits the
characteristic form of the adult to a much less degree, and has a more irregular cuboidal
form. The bract of the young, just detached Eudoxia (figured in fig. 12, b), forms the
transition from the latter to the former.

Bracteal Cavity (figs. 12, 18, bh). — The subumbrellar cavity of the hydrophyllium is
deeply campanulate or nearly conical, somewhat compressed from both lateral sides. Its
posterior or dorsal wall is nearly vertical and touches the siphon and the tentacle. Its
anterior half is filled up by one or more gonophores. The inferior and anterior trape-
zoidal opening of the cavity has been already described.

Phyllocyst (figs. 12-18, be). — The canal system of the bract is composed of a very large
dorsal sac-shaped phyllocyst, which stands vertically, and of two slender horizontal canals,
which arise from the apex of the former and diverge laterally. The large phyllocyst
occupies nearly the dorsal half of the bract, and is a vertical cylinder with rounded basal
faces, or nearly ellipsoidal, three times as long as broad. Its small internal cavity is
surrounded and almost filled with very large vacuolate entoderm-cells.

The two paired lateral canals of the bract (figs. 12-18, ex right, cl left), which arise
from the apex of the phyllocyst at right angles, are slender and run divergently towards
the two frontal corners of the bract, in their first half horizontally, in the second curved
upwards. Their blind distal ends (at the junction of the apical, ventral, and lateral
faces) are somewhat club-shaped.

Siphon (figs. 12, 13, 21, s). — The polypite is hidden in the dorsal part of the bracteal
cavity, and exhibits the usual structure of the Calyconectae — a short pedicle, a thick-
walled basigaster, a wide stomach with hepatic stripes, and a proboscis with a four- or
eight-lobed mouth.

Tentacle (figs. 12, 13, t, 26). — The single tentacle, which arises from the pedicle of
the siphon, exhibits the same structure as that of other Abylidse. Each tentillum
bears on its pedicle (fig. 26, ts) a slender reniform cnidosac, and in the proximal part of
this six to eight large spindle-shaped cnidocysts at each side of the cnido-battery (kg).
The terminal filament (tf) is slender and long.

Gonophores (figs. 22-25, isolated; figs. 12-19, included in the cavity of the bract). —
Each ripe Eudoxia usually bears a pair of gonophores in the ventral part of its cavity,
before the siphon. The two gonophores, right and left, are so transformed by mutual
pressure that their umbrella or gonocalyx (originally a tetragonal prism) assumes an
asymmetrical pentagonal form. The inner or medial faces (in which the two neigh-
bouring gonophores meet in the sagittal plane of the bract) arc flattened, whilst the outer
or lateral faces are prominent above, in form of a lateral horn. One of the five edges

116 THE VOYAGE OF H.M.S. CHALLENGER.

(n7) is dentate. The five teeth of the basal mouth are very unequal, two much larger
than the three others. The two paired gonophores together form a double body of
bilaterally symmetrical form. Sometimes they are of the same sex, at other times of
different sexes.

Genus 15. Sphenoides,1 Huxley, 1859.
Sphenoides, Huxley, Oceanic Hydrozoa, p. 61.

Definition. — Eudoxidse with a bilateral prismatic or sphenoidal bract, bounded by
eight faces, twelve edges, and twelve angles. Phyllocyst composed of a large apical sac
and a slender odd dorsal canal descending from the base of the sac. (Eudoxiae of the genus
Bassia. )

The genus Sphenoides (PI. XXXVIII.) comprises those monogastric Eudoxidas which
arise from the polygastric Diphyid genus Bassia (Genus 30, PI. XXXVII.). Its bract
has a very complicated sphenoidal form, and is distinguished by a large ovate sac of the
phyllocyst in the apical half of the umbrella, whilst a long slender odd dorsal canal
(similar to a basal spur) descends into the basal half. The original main axis of the
umbrella is strongly curved, so that its ventral part is shortened and its dorsal part
correspondingly expanded. The twelve edges of the wedge-shaped umbrella are produced
into twelve three-sided pyramidal teeth, five of which belong to the ventral (if-if),
seven to the dorsal half (uc'-uV2). The eight faces of the umbrella are four larger
paired lateral (a superior pair quadrangular, an inferior pair hexagonal) and four smaller
odd frontal faces, two superior triangular (one ventral and one dorsal) and two inferior
(a triangular dorsal and a hexagonal basal). The comparison of the young bract
(PI. XXXVIII. fig. 13) and the adult (fig. 14) exhibits the curious development of this
cuneiform hydrophyllium.

The genus Sphenoides was founded by Huxley (he. cit.) upon an Australian species,
which he rightly suspected to be the Diphyozooid of Abyla bassensis ( = Bassia quadri-
latera). This species is rather different from the Atlantic species described in the
following, the development of which from Bassia I observed in the Canary Islands ; and
from another species (Sphenoides tetragona) which I observed in the Indian Ocean. A
fourth species may be the Eudoxia of the South Atlantic, Bassia. perforata (10).

Sphenoides obeliscus, n. sp. (PI. XXXVIII.).

Habitat. — Northern Atlantic; Canary Islands, Lanzerote, February 1867 (Haeckel).

Bract (fig. 12, u, lateral view from the left side, with the included parts ; figs. 13 and
14, lateral view from the right side; fig. 13, of a younger attached Eudoxia; fig. 14, of

Spherwides= Wedge-shaped, stpvntllrii,

REPORT ON THE RIPHONOPHOR^. 117

an older free Eucloxia). — The hydrophyllium or bract lias a diameter of 10 to 12 mm., and
a sphenoidal or wedge-shaped, rather complicated form, which is best understood if we
imagine the true axis of the umbrella standing vertically, its upper or apical pole marked
by the top, the lower or basal pole by the centre of the aperture of the cavity. The
latter (or the original ostium subumbrellse) is surrounded by five prominent points, an
odd dorsal basal point (w8) and four paired lateral ; two* of these are dorsolateral basal
points (it8 right, u7 left), the two others ventro-lateral basal points (u4 right, ub left).

The opposite apical or superior part of the ripe bract (fig. 14) has the form of a house-
roof or of a triangular prism, inclined ventrally. The apical crest (nk) is strongly inclined
towards the ventral side, so that the dorsal apical point (u12) may be regarded as the
original apex of the bilateral umbrella. The opposite ventral apical point (w1), on the
contrary, marks the upper pole of the curved axis of the phyllocyst (be).

The ventral face of the bract is pentagonal and marked by five prominent points, one
odd and four paired. The odd is the above-mentioned ventral apical point (ul). The
upper pair of points are the ventro-lateral apical (ir right, u3 left) ; the lower pair of
points are the ventro-lateral basal points (u4 right, us left).

The dorsal face of the bract is quadrangular in the upper part, crest-shaped in the
lower part, and is marked by five points, three odd and two paired. The uppermost is
the odd dorsal apical point (vP), the lowermost the odd dorsal basal point (u8), the
hmdermost (between the former) the odd dorsal caudal point (a9). At the right side
(u10) and left side (u11) the two dorso-lateral points are prominent. The wedge-shaped
dorsal crest (ng) is in the ripe bract (fig. 1 4) opposite and parallel to the apical crest (nk).
All crests and edges of the bract are elegantly denticulated.

The mature bract of the free Eudoxia (fig. 14) differs from the young bract of the
sessile Eudoxoma (fig. 13) mainly in the development of a pair of arched prominent
transverse ridges or girdle-wings (u\ uw, right ; ii\ u11, left). These separate
more distinctly the thicker apical half of the hydrophyllium from its thinner ventral
half. An accurate comparison of fig. 13 (young) and fig. 14 (adult) will explain the other
differences of these two forms, which are produced by further growth.

Bracteal Cavity (figs. 13. 14, bh, seen from the right side).— The subumbrellar cavity
has the form of a, helmet or a Phrygian cap ; it is eampanulate, with strongly curved
axis, concave at the ventral, convex at the dorsal side. The cavity occupies in the young
bract (fig. 13) about two-thirds of the whole body; in the adult (fig. 14) only the basal
half. Its basal aperture, or the original mouth of the umbrella, is armed with five large
triangular, pyramidal points or teeth, one odd and four paired ; the posterior odd tooth
(it8) is the dorsal basal point ; the two ventro-lateral basal teeth (u4, us) are larger
and wider apart than the two dorso-lateral basal teeth (mb, v7). A deep ventral
groove, through which passes the stem of the cormus (fig. 13, a), is placed in the sagittal
plane of the bract, immediately to the ventral side of the subumbrellar cavity (/>//).

118 THE VOYAGE OF H.M.S. CHALLENGER.

Phyllocyst (fig. 13, be). — The canal system of the bract is composed of three parts
of a large ovate phyllocyst (be), a short peduncular canal, and a long dorsal csecum.
The small peduncular canal arises from the common stem (a), and runs immediately to
the ventral base of the large ovate phyllocyst (be). This latter is placed in the apical
half of the bract, and contains in its uppermost part a spherical oleocyst (eo). Its
rounded apex does not reach the apical crest (nk). The dorsal canal (cd) is a slender
caecum, which arises from the base of the phyllocyst. and runs along the dorsal median
line of its cavity, separated from it by a thin jelly-plate. The dorsal canal is therefore
spur-shaped and crooked, concave on the ventral, convex on the dorsal side. Its blind
lower end does not reach the basal edge (ng).

Siphon (fig. 12, s). — The polypite or siphon is suspended in the top of the subum-
brellar cavity of the bract, and may be completely hidden in it. From its short
pedicle arises the tentacle (t). A pyloric valve separates the thick basigaster (sb) from
the stomach, which exhibits eight yellow striae hepaticfe. The proboscis (sr) is very con-
tractile ; its mouth exhibits sixteen short indentations.

Tentacle (fig. 1 2, t). — The single tentacle of the siphon is distinctly segmented by
numerous constrictions, and from each constriction arises a tentillum. The pedicles (ts)
and the terminal filaments (tf) of the tentilla are long and slender. The reniform
cnidosac exhibits on its convex side six to eight longitudinal rows of medial cnidocysts
(fig. 16, km), on both sides of its base a group of large spindle-shaped lateral cnidocysts
(kg), and at the distal end a group of small pyriform cnidocysts (kp).

Gonophores (fig. 12, h; fig. 15). — The sexual Medusa which arises from the stem
at the ventral side of the siphon, has a four-winged umbrella, which is pyramidal in the
smaller apical half, prismatic in the larger basal half. Its four prominent and denticulate
wings are unequal in pairs in the younger gonophores, the two dorsal wings (fig. 12, hit)
being much larger than the two ventrals ; afterwards (fig. 15) they become nearly equal.
A long peduncular canal (fig. 1 5, cp) runs through the pedicle of the umbrella to the top
of the subumbrella («'), and divides here into four equidistant radial canals. The spindle-
shaped spermaria of the male gonophore (fig. 12, hs), and the ovate or subspherical ovaria
of the female (fig. 15, o), occupy the apical half of the subumbrellar cavity.

Genus 16. Aglaisma,1 Eschscholtz, 1829.
Aglaisma, Eschscholtz, System der Acalephen, p. 129.
Definition. — Eudoxidae with a bilateral prismatic bract, which is cuboidal in the larger
upper part, obliquely pyramidal in the smaller lower part. Phyllocyst with four cruciate
radial canals, two odd sagittal (an ascending and a descending) and two paired lateral
canals. (Eudoxiaj of the genus Calpc.)

1 Aglaisma, dyhaiafnt^Omaxaeat

REPORT ON THE S1PHONOPHOKJE. 119

The genus Aglaisma (PI. XL.) comprises those monogastric Eudoxidse which arise
from the polygastric Diphyid genus Calpe (Genus 31, PL XXXIX.). Its bract is nearly
cuboidal, similar to that of Cuboides (Genus 13), but differing from it in the possession of
a pyramidal, trigonal, or pentagonal apophysis, which descends vertically from the dorsal
and basal part of the cube. It is further distinguished by the possession of four radial
canals, arising from the small subcentral phyllocyst. Two of these four cruciate canals
are slender and vertical (an ascending and a descending), two others sacculate and hori-
zontal (a right and a left).

The genus Aglaisma was founded in 1829 by Eschscholtz for a Tropical Atlantic
species of monogastric Diphyidse, which he called Aglaisma baeri (1, p. 129) ; it is
possibly identical with our Aglaisma gegenbauri. Afterwards Huxley,1 in 1859, gave
an accurate description of two nearly related species, which he called Aglaismoides
t'sclischoltzii and Aglaismoides elongata. He suspected rightly that the former might
be the Eudoxia of the common Mediterranean Abyla pentagona. The other species,
Aglaismoides elongata, might be the Eudoxia of Calpe huxleyi. During my stay in
the Canary Islands (1867) I observed the development of the species described in the
following pages, from Calpe gegenbauri. It occurs also in a bottle of the Challenger
collection, taken at Station 346.

Aglaisma gegenbauri, n. sp. (PI. XL.).

Habitat.— Tropical and Subtropical Atlantic, Station 346 ; April 6, 1876 ; lat.
2° 42' S., long. 14° 41' W. Surface.

Canary Islands, Lanzerote, February 1867 (Haeckel).

Bract (fig. 13, b, lateral view from the right side ; fig. 14, b, from the left side; fig.
15, basal view ; fig. 16, apical view; fig. 17, dorsal view ; fig. 18, ventral view). — The
hydrophyllium or bract is subregularly cuboidal in its apical or superior half, in its basal
or inferior obliquely pyramidal, bevelled off at the ventral and basal face. The length
or height of the bract is 1*2 to l-5 mm., the breadth 0"6 to 0-8 mm.

The apical or superior face of the bract (figs. 13-16, ua) is nearly square, slightly
concave, with four equal concave edges. The phyllocyst and its two lateral casca shine
through it in the apical view. The ventral or anterior face (fig. 18, uv) has the same
square form, but is somewhat longer, and dilated towards the concave basal edge. The
dorsal or posterior face of the bract (fig. 17, ud) is more concave, and has the form of a
bilateral pentagon, which is twice as long as broad. Its odd superior edge is horizontal,
and half as long as the two divergent superior lateral edges. These are somewhat longer
than the two convergent inferior lateral edges, which meet in the basal apex of the

1 9, p. 60, pi. iv. tigs. 2, 3.

120 THE VOYAGE OF H.M.S. CHALLENGER.

pyramidal caudal apophysis. Whilst the superior half of the dorsal face is nearly
vertical, square, aud concave, its inferior peutagoual half is convex aud prominent, directed
more dorsally downwards, and bisected by a sagittal crest which becomes obsolete towards
the upper half. This crest bears about the middle of its length an odd prominent tooth
(figs. 13, 14).

The two-paired lateral faces of the bract (right, fig. 13 ; left, fig. 14) are hexagonal,
square and vertical in their upper half, irregularly hexagonal and more prominent in the
lower half. The superior horizontal edge of each lateral face is half as long as the
ventral, and one-third as long as the basal and the dorsal edge. The vertical ventral
edge is concave. The opposite dorsal edge bears a prominent tooth between its middle
and lower thirds, and so also does the obliquely descending basal edge.

The basal or inferior face of the bract is occupied by the square opening of the
bracteal cavity (fig. 15, middle portion), and behind this by the triangular ventral face
of the caudal apophysis (fig. 18).

The caudal apophysis, which distinguishes the cuboidal bract of Aglaisma from the
similar bract of Cuboides (PI. XLIL), is a bilateral oblique pyramid, which descends from
the prolonged dorsal and basal part of the hydrophy Ilium. The pyramid is five-sided,
directed downwards and dorsalwards up to the apex, which is slightly curved inwards.
The five angles of its base are marked by the five above-mentioned teeth, viz., the odd
dorsal tooth of the sagittal crest (in the inferior half of the dorsal face), the paired teeth
of the latero-dorsal edges, and the paired (somewhat inferior) teeth of the lateral basal
edges.

All the edges of the polyhedral transparent bract are elegantly denticulate, and
more or less curved.

The bracteal cavity (figs. 13-18, ui) opens in Aglaisma (as in Cuboides) more on the
basal or inferior face ; whereas in Amphiroa and Sphenoides the aperture is rather on
the ventral or anterior face. It occupies the greater part of the inferior half of the bract,
and is obliquely campanulate. The apex of the cavity is directed dorsally.

Phyllocyst (figs. 13-18, be). — The phyllocyst is a small subspherical cavity, placed
immediately above the basigaster (sb), and gives off four large canals, two odd and two
paired, which are comparable to the four radial canals of a bilateral Medusa. The
superior odd canal (cv), which corresponds to the original ventral canal of the Medusa,
ascends vertically near the median line of the dorsal face, and ends above in a spindle-
shaped diverticulum which includes an oleocyst (co). The inferior odd canal (cd)
is somewhat longer, also placed in the median plane, and descends obliquely downwards ;
it runs parallel to the neighbouring dorsal crest, and corresponds to the dorsal radial
canal of a Medusa. The two paired lateral canals (ex right, el left) are much shorter,
wider, and sac-shaped, as in Cuboides. They are geniculate and filled by large vacuolate
entoderm-cells ; their dorsal half is placed nearly horizontally, whilst their ventral half is

REPORT ON THE SIPHONOPHOR^E. 121

curved downwards. Their blind ends are directed towards the ventro-basal angles of the
lateral faces.

Siphon (figs. 13, 14, s). — The single polypite occupies originally the dorsal half of
the bracteal cavity (fig. 13), but, when two gonophores are developed, it becomes placed
between them more ventrally (fig. 14). Its thick-walled basigaster (sb) is nearly spherical.
The spindle-shaped stomach (sm) bears eight yellow hepatic stripes. The contractile
proboscis (sr) opens by an octolobate mouth (ss).

Tentacle (figs. 13, 14,/). — The single tentacle exhibits the same structure, which is
accurately described in the case of Calpe pentagona by Kolliker, Leuckart, and others.
It arises from the short pedicle of the siphon, between the basigaster and phyllocyst. It
bears numerous tentilla, each with a reniform cnidosac and a long terminal filament
coiled up spirally in fig. 19. Fig. 20 exhibits its elastic band expanded.

Gonophores (fig. 13,/; fig. 14, hf). — The bracteal cavity contains sometimes a single
gonophore (fig. 13), at other times two or even three gonophores associated, besides some
buds of vicarious function. Fig. 14 exhibits a well-developed monoclinic Eudoxia, with a
male (h) and a female (f) gonophore. The sexual manubria of both are club-shaped,
and fill about the half of the subumbrellar cavity. The umbrella is in both sexes of the
same form, distinctly bdateral, with four paired denticulate edges, prolonged at the basal
ostium into four strong triangular pyramidal teeth. The two dorsal teeth are much
larger than the two ventral. The apex of the umbrella is a curved horn, and contains
the pedicular canal ; this gives off at the apex of the subumbrella the four radial
canals, as usual.

Family V. Ees^id^, Haeckel, 1888.

Erseeidx, Hkl., System der Siphonophoren, 95, p. 33.

Definition. — Calyconectae monogastricae, representing a single cormidium, which is
composed originally of three persons ; a sterile medusome (siphon with tentacle and
bract), a sterile special nectophore (without manubrium), and a fertile medusiform
gonophore (male or female).

The family Ersaeidse comprises those monogastric Calyconectae which differ from
the preceding Eudoxidse in the possession of a so-called " special nectophore." Their
cormidium is therefore composed not of two, but of three, medusomes or persons of the
morphological value of a Medusa. The Ersseidse, as independent forms, occur much
more rarely than the Eudoxidse. I have observed two genera only, both rather rare,
Erssea and Lilsea.

The sterde medusome of the Ersseidse is composed (as in the Eudoxidse) of three
organs — viz.,bract(umbrella), siphon (manubrium), and tentacle (cnido-filament) ; all three

(zool. chall. exp. — part lxxvii. — 1888.) Hhhh 16

122 THE VOYAGE OF H.M.S. CHALLENGER.

organs possess essentially the same structure as in the preceding Eudoxidse. The bract
occurs only in two forms, one of which (Lilsea) is equal to that of Praya, or Lilyopsis ;
it is rounded and has a phyllocyst with four radial canals ; the other (Ersasa) is
similar to that of Muggisea or Diphyes; it is pointed, cucullate or spathiform, and has
a simple phyllocyst, without radial canals.

Gonophores. — The sexual medusomes of the ErsEeidse have the same form and structure
as those of the Eudoxidse ; and mainly of those species, where two or more gonophores
are produced in a single cormidium (compare above, pp. 100 and 121).

The special nectophore, which is characteristic of the Ersaeidse, and distinguishes
them from the Eudoxidse, has been originally the first gonophore. This has completely
lost its manubrium, and has, therefore, given up its sexual function ; it has been
developed merely as an organ of swimming.

Ontogeny. — On the development of the Ersseidae, compare above, pp. 100-102.

Synopsis of the Genera of Ersseidae.

Bract spathiform, with an apex. Phyllocyst simple, without radial canals, . . . 17a. Ersxa.

Bract rounded, without apex. Phyllocyst with four radial canals, . . . .17b. Lilsea.

Genus 17a. Erssea?- Eschscholtz, 1829.
Erssea, Eschscholtz, System der Acalephen, p. 127.

Definition. — Ersseidae with a campanulate or spathiform bract, divided by a collar
constriction into a proximal cowl, with an apical point, and a distal mantle, with a wide
ventral fissure. Phyllocyst large, simple, without radial canals. (Cormidia of the genus
Diphyopsis.)

The genus Erssea was founded by Eschscholtz, in 1829, to include two Atlantic
monogastric Diphyidae, differing from Eudoxia in the possession of a special nectophore,
which is prominent from the cavity of the bract (" Tubulus suctorius unicus ; pars
corporis nutritoria cavitate parva natatoria, tubuli instar prominenti instructa"). The
two species, however, which Eschscholtz there described [Erssea quoyi and Erssea
gaimardi),2 are too incompletely represented to determine with certainty their position
and their connection with any species of Diphyopsis. Possibly Erssea gaimardi may
be the free cormidium of Diphyopsis campanulifera, and Erssea bojani ( = Eudoxia
hojani, Eschscholtz), the cormidium of Diphyopsis disp>ar. I myself observed in 1866,
in the Canary Island Lanzerote, numerous free-swimming specimens of the species figured in
PI. XXXIV. as Erssea compressa, and afterwards recognised its ontogenetic connection
with Dij)hyopsis compressa (PI. XXXIII.).

1 Erssea = f{<7«?«, covered with dew. - 1, p. 128, Taf. xii. figs. 3, 4.

REPORT ON THE SIPHONOPHOR^E. 123

Ersssa, as the monogastric generation of Diphyopsis, differs essentially from Cucullus
as the free Eudoxia of Diphyes. The latter never possesses the individual " special
nectophore," which is characteristic of the former. This swimming organ must In-
regarded as the first sterile gonophore, which has lost the manubrium, the muscle-plate
of the subumbrella being the more strongly developed.

Erssea convpressa, n. sp. (PI. XXXIV.).

Habitat. — Tropical and Subtropical Atlantic; Stations, 348, 349, 352, 353, &c.
Canary Islands, Lanzerote, December 1866 and January 1867 (Haeckel).

Bract (figs. 9, 10, 11, b). — The hydrophyll or bract is in general irregularly conical
or campanulate, with a deep fissure along the truncate ventral side ; the broad basal or
inferior aperture is also obliquely truncate. An annular collar constriction, corresponding
to that part of the umbrella which was attached to the stem of Diphyopsis, divides the
bract into a smaller apical (proximal or superior) part (fig. 11, bs) and a larger basal
(distal or inferior) part. The latter encloses the siphon and its tentacle, and partly
the gonophores, like a mantle, while the former is comparable to the cowl of the mantle.
This cowl contains in its solid dorsal half the phyllocyst (cs), with a central cavity
and a globular oleocyst on the apex (co) ; its ventral half is excavated and originally
embraces the stem of siphosome (fig. 9, a) ; the two ventral wings of this cavity overlap one
another in the middle part. The length of the bract is 6 to 8 mm., its breadth 3 to 4 mm.

The campanulate mantle, or the larger distal half of the bract, exhibits around its
wide basal opening four acute triangular teeth, comparable to the four corners of the
original medusa-umbrella. The pair of dorsal teeth is larger and more prominent than
the pair of ventral teeth. The two opposite free ventral margins of the bract are
smooth.

Siphon (figs. 9,s, 10, s, 11, s). — The polypite or siphon occupies originally the axial
part of the bracteal cavity, between the dorsal tentacle (t) and the ventral nectophore
(tin). The basigaster (sb) is separated by a sharp pyloric constriction from the stomach,
the wall of which exhibits eight longitudinal hepatic ridges. The mouth of the muscular
proboscis is surrounded by sixteen short lobes (so).

Tentacle (figs. 9, t, 10, £,11, t). — The long cylindrical tentacle is distinctly articulated,
and from the constriction between every two segments arises a thin tentillum or secondary
filament (fig. 18). The terminal filament of the latter (tf) is about as long as its pedicle
(ts). The ovate cnidosac placed between them exhibits on its convex side six to eight
longitudinal rows of small medial cnidocysts (km), on its base two paired groups of
large lateral cnidocysts (six to eight spindle-shaped cnidocysts, kg, in each), and at the
distal part a trilobate group of pyriform cnidocysts (hp).

124 THE VOYAGE OF H.M.S. CHALLENGER.

Nectophore (figs. 9, 10, 11, nn). — The special nectophore, which contains no manu-
brium, occupies the ventral fissure of the bracteal cavity, in which only its basal part is
enclosed. The umbrella is a slender four-sided pyramid, distinctly bilateral, since the two
dorsal edges are stronger, and more prominent at the base, than the two ventral edges.
All these edges, and also the quadrangular basal edge, with the four prominent teeth, are
elegantly denticulate (fig. 17). The basal and ventral faces of the exumbrella are concave,
the dorsal and the two lateral faces convex.

Nectosac. — The peduncular canal, which arises from the base of the phyllocyst,
enters through the obliquely truncate top of the nectophore, and divides on the top of
the muscular subumbrella (w) into four subregular radial canals (or). These unite at the
ostium of the umbrella by a circular canal (cc) above the broad velum (v).

Gonophores (fig. 11, hm; figs. 12-14). — The young Erssea compressa possesses, besides
the sterile nectophore, only a single gonophore, the older form two or three gonophores.
These are usually of the same sex (the cormidia therefore diclinic) ; but sometimes
a male and a female gonophore are present in the same Eudoxia (the cormidium there-
fore monoclinic). The umbrella (u) of the male, as well as of the female gonophores, is
slender ovate, with four edges which are smooth in the proximal half, elegantly denticu-
late in the distal half. They are prolonged over the mouth of the umbrella, and form
four prominent triangular teeth, the two dorsal teeth being larger than the two ventral.
The subumbrella (w) exhibits in the gonophores the same four subregular radial canals,
connected by a circular canal, as in the nectophore (figs. 9-11, nn).

The male gonophores (fig. 11, hm; fig. 12) have in their umbrellar cavity a large
spindle-shaped or ovate spermarium (hm), with a wide central spadix (hx).

The female gonophores (figs. 13, 14) exhibit an ovarium of very variable size (frn).
Sometimes the entire umbrellar cavity is filled with eggs (fig. 13), whilst, at other times,
oidy a few ova (four in fig. 14) occupy its proximal half.

Genus 17b. Lil&a,1 n. gen.

Definition. — Ersseidse with a hemispherical or mitriform rounded bract, without sharp
edges and without pointed apex. Phyllocyst small, with four radial canals arising from
its base. (Cormidia of the genus Lilyopsis f)

The genus Lilsea comprises those Ersaeidse which possess a mitriform rounded bract,
without sharp edges or apical point. Its form agrees with that of the eudoxomes of
Praya and Lilyopsis. A further resemblance to the latter is given by the fact, that
each cormidium possesses a sterile nectophore, the mouth of which bears a circle of
rudimentary tentacles and four red pigment-spots (ocelli) at the distal end of the four
radial canals. They are very similar to the medusiform special nectophores of Desmo-

1 Lilxa (Ai'huici), name of a Naiad.

REPORT ON THE SIPHONOPHOR.E. 125

phyes annectens (PL XXX.). The latter agrees also in the formation of the gonophores.
Each connidiuiu possesses, besides the large vigorously swimming special necto-
phore, a cluster of small gonophores, all either male or female. The umbrella of
the male gonophores is more developed than in Dcsmophyes. Among six specimens
examined four were males and two females.

I observed half a dozen of these small interesting Ersaeidae, which will be more
accurately described on another occasion, hving in the Indian Ocean, during my voyage
from Aden to Bombay, in November 1881. I suspect that they are the detached cor-
midia of some species of Lilyopsis (Genus 25). They may bear provisionally the name
Lilsea medusina.

Family VI. Monoph yidje, Claus, 1874.

Morwphyidx, Claus, 1874, 70, p. 29.
Sphxronectidx, Huxley, 1859, 9, p. 50.

Definition. — Calyconectae polygastricae, with a single nectophore at the apex of the
long tubular truncus. Cormidia ordinate, eudoxiform, separated by equal free inter-
nodes ; each siphon with a bract.

The family Monophyidae comprises a small number of little known polygastric
Calyconectse, which are rather rare, of small size, but very interesting on account of their
simple structure. They all possess only a single permanent nectophore, and differ in
this character from the nearly allied Diphyidae, with which they were formerly united.

Eschscholtz, in his fundamental work (1829, 1, p. 134), described only a single form'
of Monophyidae, Cymba enneagonum, the free Eudoxia of which is his Cymba cuboides.
Both forms were discovered in the Straits of Gibraltar by Quoy and Gaimard, who called
the first (polygastric) form Enneagonum hyalinum,1 and the second (monogastric) form
Cuboides vitreus.

A second species of Monophyidae, inhabiting the Gulf of Trieste, was described in
1844 by Will,2 under the name Diphyes kochii, and in 1851 by Busch,3 as Muggisea pyra-
midalis. The same form was afterwards, by combination of both names, called Muggisea
kochii, by Chun (86, p. 3). He described its metagenesis and development from the
mouogastric Eudoxia eschscholtzii.

Huxley, in his excellent work on Oceanic Hydrozoa (1859, 9), described not less than
four different Monophyidae, viz. : —

(1) Sphseronectes kbllikeri, pi. iii. fig. 4.

(2) Diphyes mitra, pi. i. fig. 4 (now Cymbonectes mitra).

(3) Diphyes chamissonis, pi. i. fig. 3 (now Muggisea chamissonis) .

(4) Abyla vogtii, pi. ii. fig. 3 (now Cymba vogtii).

1 20, pi. ii.D, figs. 1-6. 2 65, p. 77, Taf. ii. fig. 22. 3 67, Taf. iv. figs. 3-6.

126 THE VOYAGE OF H.M.S. CHALLENGER.

Huxley gave an accurate description of the only nectophore observed of these four
" Diphyidae " ; he supposed (as did also his predecessors) that the second nectophore had
been accidentally lost ; it does not, however, exist at all. The genus Sphasronectes was
rightly regarded by Huxley as the type of a peculiar family — Sphaeronectidae.

During my residence in the Canary Island of Lanzerote (December 18G6 to February
1867), I observed four different species of Monophyidae, viz.: —

(1) Monophyes hydrorrhoa.

(2) Mitrophyes peltifera (PL XXVIIL).

(3) Muggisea pyramidalis.

(4) Cymba crystallus.

I was able to examine the complete metagenesis of the latter species, and the develop-
ment of its Eudoxia, Ouboides crystallus (Pis. XLL, XLII.).

A Mediterranean species of Sphieronectes, very similar to the Australian form dis-
covered by Huxley, was described in 1874 by Claus, and called Monophyes gracilis (70.
pi. iv.). He observed the development of its Eudoxia, which was formerly described by
Gegenbaur as Diplophysa inermis (7, Taf. xvi. fig. 3). Another Mediterranean Mono-
phyid described by him, Monophyes irregularis, may remain the type of this genus.
Claus replaced the term Sphaeronectidae of Huxley by the name Monophyidae, which was
accepted as more significant, in opposition to Diphyidse.

The metagenesis of the two Mediterranean Monophyidae was afterwards very accu-
rately examined by Chun (86-88). Compare his memoirs also for the history of this family.

During my voyage through the Indian Ocean (November 1881 and March 1882) and
in Ceylon, I had the opportunity of examining some very interesting new forms of Mono-
phyidae and their development, viz., Monophyes princeps and Cymbonectes huxleyi
(PI. XXVII. ). Supported by these observations, and by some specimens found in the
Challenger collection, I was able to give the following description of Monophyidae.

Nectophore. — The single nectocalyx of the Monophyidae exhibits differences in form
and structure similar to the first or proximal of the Diphyida?. Accordingly, I divide
the family Monophyidae into two subfamilies ; the first of these, Sphaeronectidae, has a
smooth hemispherical or mitriform nectophore, without sharp edges, and is allied to the
Prayidae among the Diphyidae. The second subfamily, Cymbonectidae, has a pyramidal
nectophore with five prominent edges, and is nearly allied to the Diphyopsidse and
Abylidae. The single nectophore of the Monophyidae is relatively large, of a bilateral and
quadriradial fundamental form, sometimes symmetrical, at other times asymmetrical.
The first nectophore of their larva is replaced by a permanent, often heteromorphous,
swimming-bell.

llydrcecium. — Since the single nectocalyx of the Monophyidae corresponds to the
first apical or proximal nectophore of the Diphyidae, it possesses a hydrcecium for the
reception of the retiring siphosome. This is an open hydrcecial groove, protected by

REPORT ON THE SIPHONOPHORjE. 127

two overlapping ventral wings, in Monophyes and Cymbonectes (PI. XXVII.) ; it is a
conical or campanulate hydrcecial cavity in Muggisea and Cymba (PI. XLL), a cylindrical
canal in Sphmronectes. These closed hydrcecia are secondary cavities, produced by concres-
cence of the two parallel ventral wings, which overlap the hydrcecial groove of the former.

The singular genus Mitrophyes (PI. XXVIII.) is distinguished by the lack of a
hydrcecium. It is replaced by an apical scutiform bract, which covers the nectophore
and protects the siphosome hidden between them both. The apical bract is probably
the remnant of the original primary nectophore.

Nectosac. — The subumbrella in most Monophyidse occupies the dorsal part of the
nectophore, whdst the hydrcecium is placed in its ventral part. The nectosac of
Sphmronectes and Mitrophyes is placed rather basally (as in the ancestral Medusa?), in
the other genera rather dorsally. The four radial canals are in the former genera rather
regularly disposed, but usually more bilaterally, the ventral canal being shorter, and the
dorsal longer than the two paired lateral canals. The ring-canal of the margin, which
unites them, is placed above the velum.

Somatocyst. — The acrocyst or somatocyst (" Saftbehalter ") in most Monophyidse is of
moderate size, placed in the apical prolongation of the stem ; its cavity is narrow, usually
filled by large vacuolate entoderm-cells, and its apex mostly contains an oleocyst. It is
directed sometimes vertically upwards, at other times more obliquely. Its structure is
the same as in the other Calyconectse (compare above, p. 93).

Siphosome. — The long tubular stem exhibits in the Monophyidse the same structure
as in the Diphyidas. The median ventral line of the common stem is beset at regular
intervals by the cormidia, whose number is very variable. The contracted siphosome
may be retracted into the hydrcecium more or less completely.

Cormidia. — Each cormidium (Diphyozooid or Eudoxia) is composed in the Mono-
phyidse (as in the most Diphyidse) of two medusomes ; the sterile medusome has a
bract, a siphon, and a tentacle ; the fertile medusome is a gonophore, the umbrella of
which has the usual medusoid structure, whilst the manubrium produces the sexual cells
(compare above, p. 94).

Sipjhon and Tentacle exhibit no important differences in the cormidia of the various
Monophyidse, whilst the bracts or hydrophyllia are of very different form and structure,
characteristic of the genera (compare above, pp. 95, 96).

Eudoxise. — The cormidia of some Monophyidse arrive at sexual maturity whilst
attached to the stem ; they remain sessile eudoxomes. This is the case in Mitrophyes
and Cymbonectes, and probably also in Monop>hyes. The cormidia of the three other
genera are detached from the stem, and become mature as free-swimming Eudoxise;
those of Sphieronectes are described as Dyplophysa; those of Muggisea as Cucubalus,
whilst the free Eudoxise of Cymba belong to Cuboides.

Ontogeny. — On the development of the Monophyidae, compare above, pp. 100-102.

1-2S

THE VOYAGE OF H.M.S. CHALLENGER.

I. Subfamily

Sph^ronectidj:.

Nectophore hemispheri-
cal or mitriform, with
rounded surface, with-
out sharp edges.

II. Subfamily

CYMBONECTID2E.

Nectophore pyramidal,
with five prominent
sharp edges.

Synopsis of the Genera of Monophyidae.

Hydroecium a ventral groove of the nectophore, incompletely
closed by two overlapping wings, .....

Hydrcecium a complete cylindrical canal in the ventral wall
of the nectophore, with a basal opening, ....

Hydroecium wanting. Nectophore protected by a cap-sbaped
dorsal bract ; between them is the siphosome,

Hydrcecium a ventral groove of the nectophore, incompletely
closed by two overlapping wings. Bracts spathiform,

Hydrcecium a complete coni-
cal or campanulate cavity
in the ventral wall of the
nectophore.

Bracts of the cormidia coni-
cal or spathiform, with a
deep ventral fissure, .

Bracts of the cormidia cu-
boidal, with six square
faces and a basal cavity, .

18. Monophyes.

19. Sphseronedes.

20. Mitrophyes.

21. Cymboneetes.

22. Muggixa.

23. Cym.ba.

Genus 18. Monophyes,1 Claus, 1874.

Monophyes, Claus, Die Gattung Monophyes, &c, 70, p. 29.

Definition. — Monophyidse with a rounded, edgeless, mitriform nectophore, and an
open hydroecial groove on its ventral side ; the latter includes the siphosome. which is
incompletely protected by two overlapping lateral wings. Bracts mitriform or hemi-
spherical, with rounded surface and a simple phyllocyst.

The genus Monophyes was founded in 1874 by Claus for two different Mediterranean
species of Calyconectse, which bear a single mitriform nectophore on the top of the stem.
One of these two species, Monophyes gracilis, belongs to the following genus Sphwronectes,
which possesses a closed tubular hydroecium, open only at the distal end. The other
species, Monophyes irregularis, may be retained as the type of the present genus ; it
differs from the former in the bilateral arrangement of the four radial canals of the sub-
umbrella, and mainly in the shape of the hydroecium, which is not a tubular canal, but
an open groove or infundibular cavity.2 This peculiar character is more developed in
two other species, which I have myself observed, Monophyes princeps, from the Indian
Ocean (PI. XXVII. figs. 13, 14), and Monophyes hydrorrhoa, from the Atlantic Ocean
(Canary Islands). The hydroecial groove extends here along the whole ventral side of
the bilateral nectophore, and its two edges are prominent as two free wings, one of which
overlaps the other more or less. The Atlantic species (Monophyes hydrorrhoa) is very
similar to a small Mediterranean form figured in 1885 by Chun, who supposed it to

1 Moiiophyes = Single animal (fiovo<pvvt;) ; Calyconecta with a single nectophore.

2 70, p. 32, Taf. iv. figs. 16-18.

REPORT ON THE SIPHONOPHORvE. 129

be the " primary nectophore " of Monophyes gracilis ( = Sphseronectes gracilis), afterwards
replaced by a heteromorphous secondary nectophore (87, Taf. ii. fig. 5). But this
supposition is not very probable, and I call this form provisionally Monophyes diptera,
provided that it does not belong to Cymbonectes (Genus 21). The eudoxomes of Mono-
phyes seem to ripen attached to the stem, and not to form free Eudoxise as in
Sphseronectes.

Monophyes princess, Haeckel (PI. XXVII. figs. 13, 14).

Sphseronectes princeps, Hkl., 1887, System der Siphonophoren, p. 34.
Habitat. — Indian Ocean; between the Maldive Islands and Socotra, March 1882
(Haeckel).

Nectophore (fig. 13, lateral view from the left side ; fig. 14, transverse section at the
middle of the height). — -The single nectocalyx is 6 mm. long and 3 mm. broad. Its form
is asymmetrical, nearly ovate, with a flat constriction near the base. The surface is
perfectly smooth, rounded, and without sharp edges. The transverse section (fig. 13) is
subcircular in the upper half, more ovate in the lower half.

The dorsal half of the nectophore, which includes the nectosac (w), is of a quite simple
ovoid form, bilaterally symmetrical. The ventral half, which includes the siphosome
in its hydrcecial groove, is asymmetrical. The thin frontal septum (nt), or the vertical
transverse jelly-plate, which separates the dorsal nectosac (iv) from the ventral hj'drcecial
canal (in), gives off two large parallel and vertical ventral wings, which enclose the latter.
The right wing (nx) is larger, and overlaps the smaller left wing («/), so that the ventral
opening of the hydrcecial groove becomes incompletely closed by the two overlapping
wings. The two wings are united at the apical or upper blind end of the groove, whilst
they are prolonged into two broad ovate terminal lobes at the basal or lower opening of
the groove.

Nectosac (figs. 13, 14, iv). — The subumbrella of the nectophore occupies its dorsal
half (with exception of the apical third) and is subcylindrical, slightly concave on the
dorsal, convex on the ventral side, with curved axis. The nectocalycine duct, which
arises from the top of the stem, is very short, enters into the ventral wall of the
nectosac somewhat below its rounded apex, and divides into four curved radial canals ;
the ventral of these (cv) is shorter, the dorsal (cd) longer, than the two paired lateral
canals (cl left, ex right). They are united by a circular canal above the broad
velum (v).

Hydrosdv/m (figs. 13, 14, ui). — The cavity at the ventral side of the nectophore,
which includes the retracted siphosome (as), is a flattened canal, the frontal diameter
of which is twice as great as the sagittal. It is separated from the neighbouring ventral
side of the nectosac (w) by the thin frontal septum. The hydrcecial canal is blind at

(ZOOL. CHALL. EXP. PART LXXVII. — 1888.) Hhhh 17

130 THE VOYAGE OF H.M.S. CHALLENGER.

its apex, where the top of the stem is inserted ; it is protected at its ventral side by the
two overlapping wings, and opens below by a dilated basal mouth, whence issues the
siphosome.

Somatocyst (cs). — The uppermost rounded apical part of the nectophore is occupied
by an ovate somatocyst, which arises, as the apical prolongation of the stem, between
the apical ends of the nectosac and the hydroecial canal. It is filled with large vacuolate
entoderm cells, and contains in its rounded apex a globular oleocyst (co).

The somatocyst of the Indian Monophyes princeps is wanting in the Atlantic
Monophyes hydrorrhoa, and the similar Mediterranean Monophyes diptera (Chun, 87,
Taf. ii. fig. 5). These two species represent an older phylogenetic state, since the two
parallel ventral wings of the nectophore are separated in its whole length, and not united
in the apical third ; this difference explains the absence of the somatocyst in them.

Siphosome (figs. 13, 14, as). — The common stem, retracted into the hydroecial canal
(ui), was in the specimen observed rather short (probably broken off), and bore (besides
numerous small buds) not more than five or six immature eudoxomes. Each eudoxome
had a hemispherical bract and, protected by it, a siphon with its tentacle, and a small
ovate gonophore ; the form and structure of these parts, which I could not sufficiently
examine, seems to agree with those of Monophyes irregularis.

Genus 19. Sphseronectes? Huxley, 1859.

Sphseronectes, Huxley, The Oceanic Hydrozoa, p. 50.

Definition. — Monophyidse with a rounded, edgeless, subspherical nectophore, and a
complete tubular hydroecium on its ventral side ; the latter includes the siphosome.
Bracts mitriform or subspherical, with rounded surface and a simple phyllocyst (Diplo-
physa, Genus 10).

The genus Sphseronectes was founded in 1859 by Huxley for an Australian
Monophyid, Sphseronectes kollikeri,2 which was remarkable for a single subspherical
nectophore with a tubular hydroecium. Another closely allied Mediterranean species
was described fifteen years later by Claus under the name Monophyes gracilis (70,
p. 29, fig. 8). The same author there gave the description of a similar third Monophyid
under the name Monophyes irregularis (ibid., p. 32, figs. 16, 17). We retain the
generic name Monophyes for this latter species, whilst the two former are better
placed in Huxley's original genus, Sphseronectes. The first-described Australian species,
Sphseronectes kollikeri, differs from the Mediterranean Sphseronectes gracilis in the
flatter, more depressed nectophore, and the subhorizontal, not geniculate somatocyst.
A specimen of Sphseronectes kollikeri was found by me iu the Challenger collection,
taken from the surface of the Tropical Pacific at Station 274. The same bottle con-
1 Sphxronedes = Swimming sphere (<j?>a<£«, utiktyh). 2 9, p. 50, pi. iii. fig. 4.

REPORT ON THE SIPHONOPHORJE. 131

tained a few detached Eudoxiae of this species, which fully developed represent the
monogastric Diplophysa kbllik&ri, Haeckel.

Sphasronectes may be derived from Monophyes by concrescence of the two parallel
crests or wings, which arise from the ventral side of the nectophore. The hydrcecial
groove of the latter becomes converted by this process into a closed tubular hydrcecium,
which includes the siphosome. The cormidia, which are attached to the common stem
at regular intervals, possess a subspherical bract with a simple vertical phyllocyst, and
detached from the stem represent the genus Diplophysa (compare p. 107).

Genus 20. Mitrophyes,1 Haeckel, 1888.
Mitrophyes, Hkl., System der Siphonophoren, p. 34.

Definition. — Monophyidse with a rounded, edgeless, hemispherical or mitriform
nectophore, without a true hydrcecium. Trunk free between the exumbrella of the
nectophore, and a scutiform or cap-shaped bract, depending from the junction of these
two pieces. Bracts spathiform or semi-ovate, without phyllocyst.

The genus Mitrophyes was founded by me for an Atlantic Monophyid, which I
observed living in the Canary Sea, in January 1867. I observed there two complete
specimens, a male and a female. A third specimen (female) was found in the Challenger
collection, among other pelagic animals from Station 352. The latter specimen was well
enough preserved to enable me to identify it with the former.

Mitrophyes differs from all other Monophyidse in the possession of a peculiar bract,
which covers the single nectophore like a shield or cap, and in the absence of a
hydrcecium, the trunk depending freely between those two pieces and arising from their
junction. It may be compared to a Praya or a similar Diphyid, the first nectophore of
which is rudimentary and transformed into a bract.

Mitrophyes peltij "era, n. sp. (PI. XXVIII.).

Habitat.— Tropical and Northern Atlantic, Station 352; April 13, 1876; lat.
10° 55' N., long. 17° 46' W. Surface.

Canary Islands, Lanzerote, January 1867 (Haeckel).

Nectophore. — The single large nectophore is nearly hemispherical, somewhat oblique,
its nectosac being higher in the ventral than in the dorsal half ; it is 6 to 8 mm. long,
4 to 5 mm. high. The voluminous jelly-mantle of the umbrella is twice as thick in the
dorsal part as in the ventral. The equatorial diameter of the smooth rounded exumbrella
is nearly twice as great as that of the subumbrella, and as the height of the nectophore.

1 Miirop%es = Mitrophorous, animal provided with a mitre, ph^cc, tpvhs.

132 THE VOYAGE OF H.M.S. CHALLENGER.

The obliquely egg-shaped subumbrella is much more vaulted in the ventral than in
the dorsal half; the diameter of its aperture is about equal to its height. The velum
(figs. 1, v, 2, v) is small. The four radial canals of the subumbrella are arranged
symmetrically ; the dorsal canal (figs. 1, 2, cd) is shorter, the ventral (cv) longer than
the two lateral canals {ex right, cl left). The apical canal (fig. 7, en), which arises from
their proximal junction, is short, and passes obliquely through the jelly substance of the
top in ventral direction to the somatocyst (cs).

Apical Bract (figs. 1, 6, 2, b, 7 b). — The peculiar organ, which we call the apical
bract, distinguishes at once Mitrophyes from all other Monophyida?, and from all Caly-
conectee in general. It covers the exumbrella of the nectophore in the same manner as
a cap covers the head of a man. The bract is a circular concave-convex shield, the
diameter of which nearly equals that of the subjacent nectophore.

Its morphological signification is difficult to make out ; it may be nothing other than
the reduced umbrella of a medusome, which has lost all its other parts ; but it may also
be the remnant of the primary nectophore, the place of which is taken by the permanent
nectophore afterwards developed. These two pieces are connected by a narrow short
pedicle (figs. 2, 7) which is probably the uppermost part of the original trunk. The jelly
substance of the bract is rather thin in the peripheral, thicker in its central part, and
includes here three short blind radial canals, a longer dorsal (fig. 1, cb) and two smaller
lateral canals ; from their junction arises a short bracteal canal (fig. 7, cb) which passes
through the pedicle to the somatocyst {cs).

Somatocyst (figs. 1, 2, 7, cs). — The somatocyst, or the coryphal cavity of the stem, is
a slender conical canal, placed nearly horizontally in the gelatinous umbrella of the
nectophore, in its sagittal plane, and directed towards the dorsal side. Its direct
continuation towards the ventral side is the axial canal of the trunk. Its proximal apex
is closed. From its distal base arise two lateral branches nearly opposite ; proximally the
peduncular canal of the bract (fig. 7, cb), and distally the peduncular canal of the
nectophore (fig. 7, en).

Hydrcecium. — Mitrophyes does not possess a distinct hydrcecium, but it has a very
small cavity, which may be considered as the rudimentary homologue of such a " funnel
cavity" (figs. 1, 7, ui). This rudiment of a hydrcecium is placed nearly in the apex of
the nectophore, and represents a very small funnel-shaped foveola of its exumbrella,
which surrounds the origin of the free trunk (a).

Siphosome (figs. 1, 2, 7, a). — The common trunk or stem of the siphosome in the
expanded state (fig. 1) is a very long thin cylindrical tube, attaining a length of 20 to
30 mm. The internodes between the ordinate cormidia are twice as long as these. In
the contracted state (fig. 2) the internodes disappear, and the convoluted stem becomes
hidden between the nectophore and bract. The number of the cormidia in the largest
specimen observed was between thirty and forty.

REPORT ON THE SIPHONOPHOR^E. 133

Cormidia (figs. 3, 5). — The cormidia, or the single "groups of persons," disposed
regularly in metameric order, are sessile eudoxomes, the sexual organs becoming ripe on
the stem. There are no free Eudoxise developed. In two of the three observed specimens
all the eudoxomes were female (figs. 3, 4), in the third specimen male (figs. 5, 6).
Mitrophyes, therefore, is one of the rare dioecious Siphonophorae. Each eudoxome is
composed of two medusomes, one sterile (siphon with tentacle and bract) and one fertile
(the gonophore).

Lateral Bracts (figs. 3, b, 5, b). — The bract of each cormidium is an oblongish scale,
nearly of the form of a bisected egg. Its proximal part is rounded and attached to the
stem (a), its distal part is obtusely pointed. The convex umbrella is smooth. Its sub-
umbrellar cavity covers the included siphon and gonophore only partly. There is no
phyllocyst or bracteal canal.

Siphon (figs. 3, s, 5, s). — The siphon of each cormidium is placed between bract
(dorsally) and gonophore (ventrally). Its pedicle is very short, the basigaster (sb) very
thickened, nearly spheroidal, with a dense accumulation of cnidocysts. The stomach (sm)
is ovate, thick-walled, and includes numerous scattered large cnidocysts (kc) in the
exoderm ; its entoderm possesses hepatic strise. The proboscis (sr) is very muscular,
cylindrical, with a simple circular mouth-opening (so).

Tentacle (figs. 1, 3, 5, t). — The single long tentacle which arises from the pedicle of each
siphon bears a great number of tentilla. The cnidosac of each tentillum (fig. 8) is kidney-
shaped, and bears at its proximal base only two pairs of large ovate cnidocysts (kg). The
terminal filament is about as long as the pedicle of the tentillum (figs. 5, 8).

Gonophores (figs. 3, /, 4, female ; figs. 5, h, 6, male). — Each cormidium bears only a
single gonophore without accessory sexual bells. They possess the usual shape of
medusoid gonophores in Calyconectse, and are about as large as the siphon. The sper-
maria (figs. 5, 6, hs) are more longish than the ovaria (figs. 3, o, 4). The umbrella
possesses in both sexes four regular radial canals, which are united by a ring-canal at
the basal ostium (uo).

Genus 21. Cymbonectes,1 Haeckel, 1888.

Cymbonectes, Hkl., System der Sipliortophoren, p. 34.

Definition. — Monophyidse with an angular, pyramidal nectophore, and an open
hydrcecial groove on its ventral side ; the latter includes the siphosome, which is
incompletely protected by two overlapping lateral wings. Bracts spathiform, with an
open ventral fissure, and a simple ovate phyllocyst.

The genus Cymbonectes has hitherto been known by a single species only, described
in 1859 by Huxley as Diphyes mitra, and taken only once in the Indian Ocean.2

1 Cyiribonectes = Swimming boat, Kv^onif-Tn;. "■ 9, p. 36, pi. i. fig. 4.

134 THE VOYAGE OF H.M.S. CHALLENGER.

That author observed only a single nectocalyx, and supposed that it might be a young
and imperfect Diphycs. But I find the same form in different bottles from the
Challenger, taken in the Pacific, and also in the collection of Captain Eabbe. One
nectophore only (the first or proximal) is always present, whilst there is no trace of a
second or distal nectophore. I am therefore convinced that this form is a true
Monophyid, not a Diphyid, and this the more as the peculiar character of this group is
yet more distinct in another Indian species, Cymbonectes huxleyi; I observed this
species, described in the following pages, during my stay in Ceylon. A third species,
Cymbonectes cymba, inhabits the Atlantic Ocean, and will be described afterwards.

Cymbonectes has no complete hydrcecium, but an open infundibular groove on the
ventral side of its nectosac ; it agrees in this respect with the genus Monophyes
(sensu stricto, compare p. 128), but it differs from this in the pyramidal form of its
angular nectophore.

AVhUst in Belligemma I succeeded in observing the development of the fertilized egg
of Cymbonectes huxleyi; it is very similar to that of Galeolaria aurantiaca, described
by Metschnikoff (84, Taf. vi., vii.). The four most important stages of it are figured in
PI. XXVII. figs. 9-12.

Cymbonectes huxleyi, n. sp. (PI. XXVII. figs. 1-12).

Habitat. — Indian Ocean; Belligemma, Ceylon, December 1881 (Haeckel).

Nectophore (fig. 1, lateral view from the right side ; fig. 2, dorsal view ; fig. 3, ventral
view ; fig. 4, transverse section through the middle part). — The single nectocalyx is
helmet-shaped or slenderly campanulate, 6 to 7 mm. long, 2 to 3 mm. broad ; it is some-
what broader in the upper than in the lower half. The exumbrella has five prominent,
elegantly denticulate edges which unite above in the pointed apex, and end below in the
median crests of five triangular teeth surrounding the basal mouth.

The five edges of the nectophore are arranged as in Dvphyes, one odd running along
the dorsal median line (near the nectosac), two lateral corresponding to the two lateral
canals of the latter, and two ventral forming the edges of the hydrcecial canal. From
the base of these latter arise in the lower half of the nectophore two broad triangular
wings, the larger left of which overlaps the other and thus incompletely closes the
hydrcecial groove (fig. 4) ; the free edges of these wings are strongly dentate (fig. 3).
The bases of the wings are continued above the basal ostium of the nectophore, and here
form on its ventral side two broad ovate basal lobes with elegantly denticulate edges.
These lobes support the siphosome proceeding from the basal mouth of the hydrcecial
canal.

Nectosac (fig. 2, w). — The subumbrellar cavity is ovate, twice as long as broad, and

REPORT ON THE SIPHONOPHORJE. 135

broader in the upper than in the lower half. It occupies the two distal thirds of the
nectophore, whilst its proximal third is taken by the soniatocyst (cs). Its ventral side is
separated by a thin frontal septum from the adjacent hydrcecium. The basal mouth of the
nectosac is obliquely truncate and surrounded by five strong triangular teeth, the distal
ends of the five exumbrellar crests. The two ventral teeth (as the terminal lobes of the
two hydrcecial plates) are about four times as large as the three other teeth, which
form an odd dorsal point and two paired lateral points.

Canals of the Nectosac. — The nectocalycine duct, which arises from the top of the
stem (aa), descends nearly to the middle of the dorsal median line of the subumbrella,
and divides here into four radial canals, two odd and two paired. The odd ventral canal
(cv) is the shortest, and descends immediately straight to the ostium of the nectosac.
The odd dorsal canal (cd) is the longest ; it ascends, in the dorsal median line, to the
apical top of the nectosac, and then descends downwards along its whole ventral median
line. The two paired lateral canals (right ex, and left cl) are intermediate in length
between the former and the latter, and have a strongly bent course. They run firstly
ascending towards the dorsal side, form in the upper half of the nectosac a nearly circular
loop, and then are turned ventrally and downwards. The four radial canals are united
at the ostium of the nectosac by a circular canal, which embraces the velum (v).

Hydrcecium (figs. 1-4, ui). — The funnel-cavity of the nectophore, into which the
contracted siphosome may be partly retracted, is a long, nearly cylindrical and slightly
bent canal, which occupies the two distal thirds of the ventral half of the umbrella. It
is separated from the dorsally adjacent nectosac by a thin frontal septum, and incom-
pletely closed on its ventral side by the two triangular ventral wings of the exumbrella
overlapping one another (figs. 3, 4, nx right, nl left). Its basal ostium is protected at
the dorsal side by the two terminal lobes of the ventral crest. The apex of the hydrcecial
canal touches the base of the somatocyst.

Soniatocyst (cs). — The axial canal of the tubular stem is prolonged above its apex
into a pyriform cavity, nearly filled up by large vacuolated entoderm-cells. This is the
pyriform somatocyst, which encloses in its dilated uppermost part a hydrostatic oil-
globule (co). It occupies the uppermost or apical third of the nectophore, and is far
prominent over the top of the nectosac. It is twice as long as broad, and nearly one-
third as long as the nectophore.

Siphosome. — The common tubular stem, which arises in the closed apex of the
hydrcecium, at the base of the somatocyst, proceeds through the basal ostium of the
former to a considerable length. It is beset by a series of numerous buds in the upper
part, and eight to twelve fully-developed cormidia in the lower part. These are
alternating male and female, separated by equal free internodes (fig. 1).

Cormidia (figs. 6, 7). — Each cormidium, or " group of individuals," is a eudoxome,
composed of two medusomes, a sterile and a fertde. The sterile Medusa exhibits a

136 THE VOYAGE OF H.M.S. CHALLENGER.

spathiform bract, and hidden in its cavity a siphon with its tentacle. The fertile
medusome, placed at the ventral side of the former, is a medusiform gonophore, either
male or female.

Bract (figs. 5, 6, b). — The protecting rudimentary umbrella or hydrophyllium is
similar to that of Diphyes, spathiform, or irregularly conical, with a deep ventral fissure,
and an obliquely truncate base. Its structureless jelly-plate is very thin in the lower
half, thick in the upper half, which encloses a large pyriform phyllocyst. This contains
large vacuolate entoderm cells, and an oil-globule in its apex. The truncate base of the
bract has four corners, two ventral smaller and two dorsal larger triangular lobes.

Siphon (figs. 5-7, s). — The single polypite which is attached on the top of the sub-
umbrellar cavity of the bract has the formation usual in the Calyconectse, a short pedicle,
an ovate basigaster with very thick exoderm, full of cnidocysts (sb), a utricular stomach
with thick entoderm (sm), and a very protractile proboscis (sr) ; the distal mouth-
opening of the latter may be expanded in form of a circular suctorial disc (fig. 5, ss).

Tentacle (figs. 5-7, t). — The single tentacle which arises from the pedicle of the
siphon is of medium size, and bears a row of ten to fifteen or more tentilla. Each of
these lateral branches bears upon its club-shaped pedicle a reniform cnidosac (fig. 8, km).
This includes on its convex side about four to six longitudinal rows of smaller paliform
cnidocysts, and at its base, on both sides, three very large ensiform cnidocysts ; the
terminal filament (tf) is usually coiled up, and armed at the distal end with a hemi-
spherical group of pyriform cnidocysts, provided with long cnidocils (kp).

Gonophores (figs. 5, 6). — The sexual medusoids alternate regularly in the cormidia, so
that each two neighbouring ones form together a diclinic pair. The male eudoxomes (fig. 6)
are nearly of the same shape as the female (fig. 5). Each gonophore is an ovate or club-
shaped sac, placed at the ventral side of the siphon. The rudimentary umbrella, which
possesses the usual four radial canals, and the uniting marginal canal, embraces closely
the manubrium. The spadix or central canal is large in the spermaria (fig. 6, hx), small
or rudimentary in the ovaria (fig. 5,f).

Genus 22. Muggisea,1 Busch, 1851.
Muggisea, Busch, "Wirbellose Seethiere, &c, 67, p. 48.
Definition. — Monophyidse with an angular pyramidal nectophore and a complete
infundibular hydrcecium on its ventral side. Bracts spathiform or conical, with a deep
ventral groove, a bevelled basal face, and a simple ovate phyllocyst.

The genus Muggiwa was founded in 1851 by Busch (67, p. 48) for a Mediterranean
Monophyid, which Will had figured seven years before uuder the name Diphyes kochii
(65, p. 77, Taf. ii. fig. 22). The identity of these two forms was demonstrated in 1882

1 Mtiggixa = Inhabitant of the port of Muggia, near Trieste.

REPORT ON THE SIPHONOPHORJE. 137

by Chun, who called it Muggisea kochii (86, p. 1157, Taf. xvii. fig. 2). Chun demon-
strated that this poly gastric Calyconecta is a true Monophyid, and that the cormidia,
arising from the common stem, become detached and sexually developed as the free
monogastric generation, which was described by Busch under the name Eudoxia
eschscholtzii.1 Chun also gave the full description of its ontogeny, and found that the
larva, arising from the fertilised egg of Eudoxia eschscholtzii, does not possess the
pentagonal pyramidal nectophore of Muggisea, but the edgeless campanulate nectophore
of Monophyes ; the latter afterwards buds from the base of the former, and remains
when the former is detached. Chun supposed, therefore,, that three different genera-
tions should be distinguished in this species — (l) Monophyes pyramidalis (85, fig. 1),
(2) Muggisea kochii (fig. 2), and (3) Eudoxia eschscholtzii (fig. 3). I cannot agree
with this opinion, but I regard the first form (fig. 1) only as the larva of the
second (fig.. 2). The primary edgeless nectophore of Monophyes is only a provisional
larval organ, and the fact that it is afterwards replaced by the secondary five-
edged pyramidal nectophore of Muggisea may be explained by the fundamental law
of biogeny — by the hypothesis that Monophyes is the original ancestral form of
Muggisea.

The mature Eudoxia of Muggisea is very similar to the monogastric genus Cucullus,
the Eudoxia of Diphyes. It differs in the rounded and edgeless surface of the conical
or spathiform bract, which has three or five edges in Cucullus. In respect of this
difference, the name Cucubalus (given in 1824 by Quoy and Gaimard, 24) may be
retained for it. The spathiform bract is obliquely conical, with a deep ventral groove,
rounded dorsal convexity, pointed apex, and simple phyllocyst (compare above, Genus
11b, p. 109). The free Eudoxia of the Mediterranean Muggisea kochii may, therefore,
bear the name Cucubalus eschscholtzii.

A second species, slightly differing from the Mediterranean one, was observed by me
in the Canary Island Lanzerote, and may retain the name Muggisea pyramidalis; it
differs from the former mainly in the size of the conical hydrcecium, the top of which
attains half the length of the nectosac. The free Eudoxia of this Atlantic species has
a conical bract, with a blunt apex and an ovate larger phyllocyst ; it rnay be called
Cucubalus pyramidalis.

A third species of Muggisea is probably the Tropical Pacific form, described by Huxley
in 1859 as Diphyes chamissonis.2 It agrees with Muggisea pyramidalis in the size of
the high hydrceciurn, but differs from this Atlantic and from the Mediterranean species
in the more campanulate form of the nectophore, the denticulate shape of its edges, and
the stronger teeth of its mouth. The free Eudoxia of this Pacific species may, perhaps,
be Cucubalus cordiformis of Quoy and Gaimard.3 Muggisea differs from the preceding

1 67, p. 33, Taf. iv. figs. 7-10 ; Taf. v. figs. 1-9.

2 9, p. 36, pi. i. fig. 3. 3 2, p. 94, pi. iv. figs. 24-27 ; 24, pi. vi. fig. 1.
(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 18

138 THE VOYAGE OF H.M.S. CHALLENGER.

Cymbonectes mainly in the complete infundibular cavity of the hydroecium, and, there-
fore, bears to it the same relation that Sphasronectes exhibits to Monophyes.

Genus 23. Cymba,1 Eschscholtz, 1829.
Cymba, Esch., System der Acaleplien, p. 133.

Definition. — Monophyidse with an angular, pyramidal nectophore, and a complete in-
fundibular hydroecium on its ventral side. Bracts cuboidal, with six quadrangular faces,
and two lateral lobes arising from the base of the phyllocyst.

The genus Cymba of Eschscholtz comprised in the system of its founder three
different species, the first of which [Cymba sagittata) belongs to a different genus of
Calyconectae (it is an Abylid). The second species, which I retain as the type of our
genus, is the Mediterranean Cymba enneagonum, Esch. ( = Enneagonum hyalinum, Quoy
et Gaimard, 2, pi. v. figs. 1-6). The monogastric generation, or the Eudoxia of this
polygastric Monophyid, is the third species of Eschscholtz, Cymba cuboides ( = Cuboides
vitreus, Quoy et Gaimard, not Huxley !).

Different from this typical and oldest known Mediterranean form is a second, Austra-
lian, species, which Huxley described very accurately in 1859, under the name Abyla
vogtii (9, fig. 46, pi. ii. fig. 3). He rightly suspected that his Cuboides vitreus (not
identical with that of Quoy et Gaimard) might be the detached Eudoxia of the former ;
he found both together at the same place on the south coast of New Guinea.

A third species, Cymba nacella, was found by me in 1881 in the Indian Ocean, and
will be described on another occasion. It is more similar to Cymba vogtii ( = Abyla
vogtii, Huxley) than to the two western species. Its Eudoxia is Cuboides nacella.

The fourth species, here described as Cymba crystallus, was observed living by me
in the Canary Islands in 1867, and from these living specimens are taken the figures on
Pis. XLI. and XLII. (compare above, p. 111). The same form occurred in the Challenger
collection, having been taken in the Guinea current at Station 348.

The remarkable cuboidal form of the bracts, and the bilobate horizontal diverticulum
of their phyllocyst, distinguishes Cymba at once from all other Calyconectae.

Cymba crystallus, n. sp. (Pis. XLI., XLII.).

Abyla crystallus, Haeckel, 18G7, MS. Canar.

Habitat. — Tropical and Subtropical Atlantic, Station 348; April 9, 1876: lat.
3° 10' N., long. 14° 51' W. Surface.

Canary Islands, Lanzerote, February 1867 (Haeckel).

1 Cymba = Boat, xv/*ISri.

REPORT ON THE SIPHON OPHORiE. 139

Nectophore (fig. 1, basal view; fig. 2, apical view; fig. 3, dorsal view; fig. 4,
ventral view ; fig. 5, lateral view from the left side). — The single nectophore (or the
apical nectocalyx) has a diameter of 10 to 15 mm., and a complicated polyhedral form.
In that position which is regarded as the normal in figs. 3, 4, and 5, the two parallel
axes of the nectosac and of the hydrcecium stand vertically. The umbrella of the
nectophore appears composed of a quadrilateral pyramid in the apical half, and of a poly-
gonal prism in the basal half.

The apical view of the nectophore (fig. 2) exhibits a rather regular quadrilateral
pyramid. Its four perradial edges (the dorsal nd, the opposite ventral or coryphal nk,
and the two lateral, right and left) meet in the central apex of the pyramid at right
angles. The four faces separated by them are irregularly rhombic, the two dorsal (left ud',
and right ud") and the two apici-ventral faces (left ua', and right ua"). Each of these
four faces is slightly concave, and in the middle between each two pyramid, edges is pro-
longed into a descending pyramidal apophysis ; these four basal apophyses alternate
regularly with the four pyramid edges, and are of course interradial.

The basal view of the nectophore (fig. 1) shows that these four interradial basal
apophyses are three-sided pyramidal, and that their inferior crests or basal edges are
directed radially towards the centre of the basal face. The centripetal end of the basal
edge of the two dorsal apophyses passes over directly into the two lateral teeth of the
mouth of the nectosac, whereas the centripetal end of the basal edge of the two ventral
apophyses finally passes over into the two smaller dorsal teeth of the mouth of the
hydrceciuni. The four basal faces of the nectophore, which are separated by those four
interradial basal crests, are also concave, and have a bilateral-rhombic, or, strictly speaking,
pentagonal form. The ventral basal face (uv) is somewhat smaller than the dorsal basal
face (ug), and the two pentagonal lateral basal faces are intermediate between them.

The ventral view of the nectophore (fig. 4) therefore exhibits the smaller ventral basal
face (uv) surrounded by four larger faces (fore-shortened) ; the two ventral basal faces
(ux right, ul left) and the two ventral apical faces (ua" right, ua' left). The somato-
cyst (cs), with its apical oleophore (co), and beyond it the hydrcecium (ui), with the
included siphosome, appear through the ventral wall of the nectophore in this view
(fig. 4). The basal opening of the hydrcecium (ui) is surrounded by four serrate trian-
gular teeth, two smaller ventral and two larger dorsal.

The dorsal view of the nectophore (fig. 3) exhibits the two large quadrilateral dorsal
apical faces (ud' left, and ud" right), and beyond them the pentagonal dorsal basal face of
the nectosac may be seen through the dorsal wall of the nectophore, and above it the
oleocyst (fig. 3, co).

Nectosac (fig. 6, w, lateral view, right side ; fig. 5, lateral view, left side ; fig. 3, w,
dorsal view ; fig. 2, w, apical view ; fig. 1, iv, and 7, basal view). — The nectosac, or the
muscular subumbrella of the nectophore, includes a slenderly ovate cavity, which in the

140 THE VOYAGE OF H.M.S. CHALLENGER.

contracted state is three to four times as high as broad. Its height equals half the
height of the complete nectophore. Its dorsal face is more convexly vaulted than the
ventral, which is nearly in contact with the dorsal wall of the hydrcecium. The canal
of the nectophore (fig. 6), which arises from the constriction between somatocyst (cs)
and hydrcecium (ui), descends nearly vertically to the centre of the ventral median line
of the nectosac, and here gives off the four radial canals, which have very different lengths.
The shortest is the ventral canal of the nectosac (fig. 6, cv) ; it extends only through the
basal half of the nectosac. The longest, on the contrary, is the opposite dorsal canal
(cd) ; it runs from the basal circular canal (cc) along the whole dorsal side (in the dorsal
median line of the nectosac), and then from its top downwards through the apical half of
the ventral line. The two symmetrical lateral canals (ex right, and cl left) are equal and
form an S-shaped loop ; they ascend from the basal circular canal (cc) in the dorsal half
of the nectosac vertically, send off into its apical third a slender caecal sac (cy), and then
descend in the ventral half, meeting each other and the two other canals near to the
centre of the ventral line.

The mouth of the nectosac (figs. 1, no, and 7, no, basal view; fig. 8, no, lateral view
from the right side) is surrounded by a broad velum (v) and armed with five serrate
teeth of nearly equal size, the odd dorsal tooth (fig. 8, nd) is perradial ; the two paired
dorso-lateral teeth (n1 left, n2 right) give off the two dorsal basal crests of the nectophore ;
finally, the two paired ventrolateral teeth (fig. 8, n3 left, n4 right) may be regarded
as separated branches of a forked (originally odd) ventral tooth.

Hydrcecium (figs. 1 and 7, ui, basal view; fig. 2, ui, apical view; fig. 4, ui, ventral view ;
fig. 5, ui, lateral view from the left side ; fig. 6, ui, from the right side). — The hydrcecium
or the funnel cavity of the umbrella completely includes the retracted siphosome ; it is
slenderly campanulate or nearly cylindrical, and about as large as the nectosac, which
is placed at its dorsal side. The vertical main axes of these two organs are nearly
parallel ; but the apical half only of the hydrcecium is in immediate contact with the
basal half of the nectophore, whilst the basal half of the former projects freely beyond
in the form of a short and wide campanulate tube (figs. 5, 7, 8, ui). The basal mouth
of the latter is the lowermost base of the entire nectophore. and is armed wTith two pairs
of serrate teeth, the two teeth of the dorsal pair being larger than those of the ventral
pair (figs. 7, 8).

Somatocyst (fig. 4, cs, ventral view ; figs. 5, 6, cs, lateral view). — The somatocyst or
the coryphal cavity is ovate or spindle-shaped, about half as long and broad as the
hydrcecium. It is placed at the apex of the latter, in the apical prolongation of its vertical
main axis, and is nearly filled with large polyhedral entoderm cells. Its dorsal wall is
in contact with the upper half of the ventral wall of the nectosac. Its apex bears a
vertical oleocyst, containing a large ovate oil-bubble, about one-third as long and broad
as the somatocyst.

REPORT ON THE SIPHONOPHOR^E. 141

Siphosome (figs. 4-6, i). — The common trunk bears In its upper part very numerous
buds of cormidia (i), in its lower part ten to twelve or more well-developed eudoxomes.
These are soon detached from the stem and swim about as free Eudoxise of the special
form represented in PI. XLII. as Cuboides crystallus (compare their description above,
p. 112, Genus 13). When fully contracted the entire siphosome, with all cormidia, is
hidden in the hydrcecium (figs. 4-6).

Family VII. Diphyid^e, Eschscholtz, 1829 (sensu restricto).

Diphyulse, Esch., System der Acaleplien, 1, p. 122.

Definition. — Calyconectae polygastricsB, with two nectophores at the apex of the long-
tubular truuk. Cormidia ordinate, eudoxiform, separated by equal free internodes, each
siphon with a bract.

The family Diphyidse, as defined in my system, comprises only those polygastric
Calyconectse which bear two permanent nectophores on the top of the stem. I exclude,
therefore, those forms, formerly united with them, which possess only a single nectophore
(Monophyidse). I exclude, further, on practical grounds, the monogastric independent
forms, which are connected with the Diphyidae by metagenesis, the so-called Diphyo-
zooids, the families (IV. and V.) Eudoxidse and Ersseidas. The Diphyidae are very
common in all the seas of the world, far more frequent than all other Siphonophorae, and
richer in different species than the other Calyconectae.

The first Diphyid was described in 1804 by Bory under the name Biphora bipartita
(13, vol. i. p. 134). Cuvier founded for it the genus Diphyes (in 1817, 91), and
Chamisso figured the same as Diphyes dispar (16, p. 365, Tab. xxxiii. fig. 4).

The naturalists of the "Astrolabe." Quoy and Gaimard, discovered in 1826, in the
Straits of Gibraltar, a greater number of Diphyidse, and distinguished in this family
six different genera: — 1. Diphyes (campanulifera) ; 2. Calpe (jpentagona) ; 3. Abyla
(trigona) ; 4. Cymba (sagittata) ; 5. Enneagonum (hyalinum) ; and 6. Cuboides
(vitreus) (20). These and some other Diphyidse were described and figured by the same
authors in 1833 in the Zoophytes de l'Astrolabe (2, pp. 81-106) as fifteen different
species of the genus Diphyes, nearly every species of which is now the type of a special
genus.

Eschscholtz (1, p. 122) gave the first accurate description and a better systematic
arrangement of the Diphyidse ; they form, in his System der Acalephen, the first of the
three large families of Siphonophorse. He distinguished six genera ; three of these
(Eudoxia, Ersasa, Aglaisma) are monogastric, and form now our family Eudoxidre (p. 103);
the three others (Abyla, Cymba, Diphyes) are polygastric ; one of these (Cymba) is
according to my observations a Monophyid, so that only Diphijes and Abyla remain
as types of true Diphyidae.

142 THE VOYAGE OF H.M.S. CHALLENGER.

Blainville, in his Actmologie (24, pp. 125-140), and Lesson, in his Acalephes (3,
pp. 425-465), collected the scattered descriptions and figures of the older observers, and
distinguished a greater number of genera, but without any clear anatomical under-
standing and without critical judgement.

The excellent naturalists, who, in the sixth decade of our century (1853 to 1859),
did so much for the anatomical knowledge of Siphonophorae, gave also the first accurate
description of the typical Diphyidse, mainly Diphyes and Abyla (4-10). Kolliker
(4, Tab. ix.-xi.) gave an excellent description of three Mediterranean types — Praya
diphyes, Diphyes sieboldii, and Abyla pentagona. Vogt (6, Tab. xvi.-xxL) gave
beautiful drawings of the same forms, and also of Galeolaria aurantiaca. But the
greatest progress in the knowledge of Diphyidse, mainly regarding their development
and connection with Eudoxidse, was made by Gegenbaur (7 and 10) and by Leuckart
(5 and 8). The former described, too, a greater number of new species (of Praya,
Diphyes, and Abyla, 10).

The most complete anatomical and systematic description of the polygastric
Diphyidse, and of their offspring, the monogastric Eudoxidse, as alsD the best and
fullest account of the whole family up to our days, was given in 1859 by Huxley
(9, pp. 30-66, pis. i.-v.). He restricted the family Diphyidae to the genera Diphyes and
Abyla in the sense of Eschscholtz, and separated them from Praya, as the type of
another family, Prayidse (Kolliker, 4, p. 33). He gave, further, the first accurate descrip-
tion of numerous Diphyozooids (or Eudoxidse), of seven different genera, and indicated
probable ontogenetic connection with different forms of Diphyes and Abyla.

During my residence in the Canary Islands, from December 1866 to February 1867,
I had the opportunity of examining typical representatives of all the eight genera of
true polygastric Diphyidae which are described in the sequel, and there I drew from
nature the figures, which will be seen in Pis. XXXI. to XLII. of this Report. The
greater number of the Diphyidse, there observed by me, were afterwards found again in
the collection of the Challenger, mainly in bottles containing surface animals, which were
taken in the Tropical and Subtropical Atlantic (Stations 334 to 354; March 14 to
May 7, 1876). In Lanzerote I observed directly the metagenesis of Diphyes (with
Cucullus), Diphyopsis (with Erssea), Abyla (with Amphiroa), Bassia (with Sphenoides),
and Calpe (with Aglaisma).

Nectophores. — The two nectocalyces, which, in all Diphyidse, are placed at the top of
the stem, appear in three different stages of phylogenetic development, and these deter-
mine the division of the family into three divergent subfamilies. The first subfamily,
Prayidse, has two nectophores of nearly equal size and similar form, opposed to one
another ; sometimes the first is somewhat smaller than the second ; their surface is
rounded, the jelly-substance very soft. Their shape is either mitriform or reniform
[Praya, PI. XXXI.), or more hemispherical (Lilyopsis).

REPORT ON THE SIPHONOPHORiE. 143

The two nectophores of the second subfamily, Diphyopsid.se (PL XXXIII.), are also of
nearly equal size and similar form ; but they are pyramidal, pentagonal, and placed one
behind the other. Their junction is very loose in Galeolaria, whilst in Diphyes and
Diphyopsis the apical part of the second is hidden in the hydrceciurn of the
first nectophore. The sharp edges are often elegantly denticulate, and the hyaline
jelly-substance of the umbrella is rather hard and firm, cartilaginous, as also is that
of Abylidse (Pis. XXXV. -XL.).

The differentiation of the two nectophores attains the highest degree in the third sub-
family, Abylidse. The first (proximal or apical nectophore, often also called superior or
anterior) is here always symmetrical and much smaller than the second (distal or basal
nectophore, often called inferior or posterior) ; this is more or less asymmetrical. Both
nectophores are here polyhedral, prismatic, or truncate-pyramidal, with numerous poly-
gonal faces and sharp prominent edges. The form of the second nectophore and its basal
ostium is especially characteristic ; it offers three prominent wings in Abyla (trigona),
four in Bassia (tetragona), and five in Calpe (pentagona).

Canals of the Nectophores. — Each of the two nectophores constantly possesses four
radial canals in the subumbrella, which are united above the velum by a circular canal.
The size, course, and form of the four vessels are very variable, according to the place of
their apical junction, where the nectocalycine duct, coming from the top of the stem,
enters into the subumbrella. This point of junction is usually placed not at the apex of
the nectosac but in its ventral median line, more or less dislocated downwards, so that
the ventral canal (cv) is shorter, and the dorsal (cd) longer than the two symmetrical
lateral canals (ex right, cl left) ; the latter are often more or less curved or loop-shaped.
The ventral canal is very short, rudimentary, or even lost, in the first nectocalyx of
Galeolaria, because here the point of junction has quite descended, and the nectocalycine
duct enters into the base of the subumbrella, instead of into the apex. The opposite
dorsal canal is so much the longer.

Hydrceciurn. — The differences which the hydrceciurn offers in the Diphyidse, have
been already mentioned above (p. 93). The Prayidse are distinguished by a cylindrical
hydrcecial canal open at both ends, composed of the ventral grooves of the two opposite
nectophores, fitting one into another. Galeolaria has no true hydrceciurn, since the
apex of the second nectophore is simply attached to the base of the first, and the
siphosome is suspended freely between them. All other Diphyidse have a conical or
campanulate hydrcecial cavity on the ventral side of the first nectophore, and as its
continuation, a hydrcecial canal on that of the second ; this is sometimes an open groove,
protected by two overlapping wings, at other times a closed canal, produced by
concrescence of the two wings.

Somatocyst (cs). — The acrocyst or somatocyst (" Saftbehalter ") is wanting in the
Prayidse and in Galeolaria ; it may be replaced in the former by the ascending pallial

144 THE VOYAGE OF H.M.S. CHALLENGER.

canal. All other Diphyidse possess a somatocyst in the first or apical nectophore ; it
must be regarded as the uppermost part of the original common stem, overgrown and
enclosed by jelly-substance of the first nectophore. The somatocyst is usually rather
large, spindle-shaped, or ovate, sometimes more cylindriaal, at other times more ovate.
Usually it ascends from the apex of the hydrcecium ; but in Abyla it descends along its
ventral side. The structure is the same as in the other Calyconectse (compare above,
p. 93).

Siphosome. — The tubular trunk or common stem of the Diphyidae is very contractile,
and beset at regular intervals with the cormidia, the number of which is very variable.
The stem is very long in the lower and older forms of the family, in the Prayidse and
Galeolaria, where it sometimes attains a length of more than one metre, and bears
more than one hundred cormidia. Their size arjd number are much smaller in the
specialised Abylidse, intermediate in the Diphyidae. The contracted stem may usually
be retracted more or less completely into the hydrcecium. The structure of the stem is
described above (p. 94).

Cormidia. — The cormidia of the Diphyidse, or the Diphyozooids of Huxley (9, pp.
57-66), occur in two different principal forms, eudoxomes and ersseomes. The majority
of the genera possess eudoxomes ; each cormidium is composed of a sterile medusome
(bract with siphon and tentacle) and a fertile medusome -(gonophore). The two genera
Lilyopsis and Diphyopsis possess ersseomes, a sterile special nectophore, as locomotive
person, being added to the euxodome.

Bracts. — The bracts or hydrophyllia are of very different form and structure,
characteristic of the single genera and even of the three subfamilies. The bracts are
mitriform and rounded in the Prayidse, spathiform or conical in the Diphyopsidse,
prismatic or polyhedral in the Abylidse. Besides, the form and place of the phyllocyst,
and the number, form, and course of the radial canals which arise from its base,
exhibit characteristic differences in the various genera.

Siphon and Tentacle. — The form and structure of the polypites exhibit no
important differences in the cormidia of the various Diphyidae. The structure, too,
of the tentacles is in general the same ; but the special form of the tentilla, and
especially the composition of the cnidosacs and the arrangement of their different cnido-
cysts, are subject to many specific variations.

Eudoxiee. — The minority of the Diphyidse produce sessile eudoxomes, which maturate
whilst attached to the stem. This is the case in some of the Prayidse and in Galeolaria.
In all the other Diphyidas they become early detached from the stem, and maturate as
free Eudoxise (compare above, p. 101).

Ontogeny. — On the development of the Diphyidse, compare above, pp. 100-102.

REPORT ON THE SIPHONOPHORiE.

145

Synopsis of the Genera of ' Diphyidse.

III. Subfamily
Abylim:.

Two nectophores of very
different size and form,
one placed behind the
other ; both prismatic,
with polygonal faces
and sharp edges.

I. Subfamily

PRAYID.E.

Two nectophores of nearly
equal size and similar
form, opposite to one an-
other, edgeless, rounded.

II. Subfamily

Diphyopsid.e.

Two nectophores of nearly
equal size and similar
form, one placed behind
the other, pyramidal,
five-edged.

Bracts of the cormidia
hemispherical, cup-
shaped or helmet-
shaped, edgeless, round-
ed. Phyllocyst with
four radial canals.

Bracts of the cormidia
pyramidal, conical, or
spathiform, with a
pointed apex, and an
obliquely bevelled basal
face and a deep ventral
fissure. Phyllocyst

ovate, simple or rudi-
mentary, without radial
canals.

Bracts of the cormidia six-
sided prismatic. Phyl-
locyst descending, with
two lateral canals at its
apex.

Bracts of the cormidia
four-sided prismatic,
below wedge-shaped. <j
Phyllocyst ascending,
with an odd basal canal.

Bracts of the cormidia f

cuboidal, with a caudal J

apophysis. Phyllocyst j
with four radial canals.

Cormidia (or Eudoxiae)
without special necto-
phores,

Each cormidium (or Eu-
doxia) with a special
nectophore, .

Cormidia without special
nectophores, sessile.
First nectophore with-
out hydrcecium, .

Cormidia without special
nectophores, free Eu-
doxise. First necto-
phore with a conical
hydrcecium,

Each cormidium (or each
Eudoxia) with a special
nectophore, free. First
nectophore with a coni-
cal hydroeeium, .

24. Praya.

25. Lilyopsin.

26. Galeolaria.

27. Diphyes.

28. Diphyopsis.

Basal nectophore three-
sided prismatic, with
three wing-shaped edges.
Mouth trigonal, . . 29. Aby/a.

Basal nectophore four-
sided, pyramidal, with
four wing-shaped edges.
Mouth tetragonal, . 30. Bosnia.

Basal nectophore five-
sided prismatic, with
five wing-shaped edges.
Mouth pentagonal, . 31. Calpe.

Subfamily Prayid^;.

Genus 24. Praya,1 Blainville, 1834.
Praya, Blainville, Manuel d'Actinologie, 24, p. 137.
Definition. — Diphyidse with two rounded, reniform or mitriform, edgeless nectophores
of similar form and subequal size, opposed to one another. A hydrcecial canal is formed
by the opposite hemicylindrical ventral grooves of the two nectophores. Bracts hemi-
spherical, helmet-shaped or reniform. Phyllocyst with (four) radial canals. Cormidia
without special nectophores.

1 Prai/o=Porto Praya, the name of a place in the Cape Verde Islands, where this Siphonophore was first observed.
(ZOOL. CHALL. EXP — PART LXXVIL — 1888.) Hhhh 19

146 THE VOYAGE OF H.M.S. CHALLENGER.

The genus Praya, and the following genus Lilyopsis, compose together the sub-
family Prayidae, differing from the other Diphyidae (Diphyopsidae and Abylidae) mainly
in the rounded, edgeless exumbrella of the nectophores, which consist of a particularly
soft jelly-substance, much softer than in the latter. The two nectophores are of similar
form and nearly equal size, one opposed to the other, and not the first before the second
(as in the Diphyopsidae and Abylidae). The rnitriform or reniform nectophores have a
longitudinal furrow on their ventral side, and the two hemicylindrical furrows are so
applied one to another as to form a hydrcecial tube, in which the upper part of the
siphosome can be retracted. The bracts are navicular or reniform, provided with four
irregular radial canals.

The best known type of the genus Praya is the large Mediterranean form described
by Gegenbaur as Praya maxima (7, Taf. xvii. figs. 1-4). Perhaps different from this
species is another Mediterranean form, which also inhabits the North Atlantic, Praya
cymbiformis, delle Chiaje (18), very accurately described byLeuckart (5 and 8). A third
species, differing from the two former in the form of the nectophores and bracts and their
canals, is the tropical Atlantic Praya galea, which I observed living in the Canary
Island Lanzerote, in February 1867. Scattered bracts of it are found in a bottle in the
Challenger collection from Station 352.

Praya galea, n. sp. (Pis. XXXL, XXXII.).

Praya galea, Haeokel, System der Siphonophoren, 1888, p. 35.

Habitat. — Tropical and Subtropical Atlantic, Station 352 ; April 13, 1876 ; lat.
10° 55' N., long. 17° 46' W. Surface.

Canary Islands, Lanzerote, February 1867 (Haeckel).

Nectophores (PI. XXXI. figs. 1-7, natural size ; fig. 1, lateral view ; fig. 2, dorsal
view ; fig. 3, apical view of the two united, fig. 4, of the two separated nectophores ;
fig. 5, first (smaller) nectophore from the left side ; fig. 6, second (larger) nectophore
from the right side ; fig. 7, the same from the ventral side). The two large nectophores
or nectocalyces, which are the powerful locomotive organs of the long chain-like body,
are both of similar kidney-shaped form, but of different sizes. The first, apical or
proximal nectophore is somewhat smaller than the second, basal or distal swimming bell ;
both possess a deep longitudinal groove on their ventral side, and are so opposite one to
another at the top of the stem, that the larger distal bell is placed more below and
embraces the smaller proximal bell by means of its two lateral ventral wings (figs. 3, 4).
The smaller nectophore was in the largest specimen, which I examined living in the
< 'anary Islands, 40 mm. long and 25 mm. broad ; the larger (second) nectophore 50 mm.
long and 35 mm. broad. Another specimen had only two-thirds of this size.

REPORT ON THE SIPHONOPHORiE. 147

Each of the two nectophores has in general the form of a kidney or bean, with a
deep longitudinal sulcus or groove at its ventral side, corresponding to the hilus of the
kidney. This furrow is the hydrcecial sulcus (fig. 4, ni) included between the two
lateral longitudinal wings of the bell (nx right wing, and nl left wing, in figs. 2-7). In
the middle of this groove, in the ventral median line of the nectophore, arises its pedicle,
a small triangular vertical plate (fig. 4, np). The proximal apex of the triangle
(fig. 7, np) connects the bell with the top of the siphosome (fig. 4b, a). The dorsal or
abaxial side of the nectophore, as well as its lateral sides, are equally rounded, without
crests, and the two ventral nearly parallel longitudinal wings are its only edges. The
jelly-substance of the umbrella is, as in the other species of the genus, extremely soft and
nearly diffluent, so that the bell, taken out of the water, loses its natural form.

Nectosac. — The nectosac, or the subumbrellar cavity of the nectophores (figs. 5-7, w),
is relatively larger than in the other species of the genus hitherto described. It occupies
nearly the aboral half of the umbrella, whereas in the latter it takes up only one-third or
one-fourth of it. The form of the nectosac is sometimes campanulate or ovate (figs. 1, 6),
at other times hemispherical or subglobular (figs. 2, 5). Its axis is not identical with the
longitudinal axis of the reniform bell, but inclined towards it at an acute angle. The
basal opening of the nectosac is circular and surrounded by a broad velum (figs. 2, 6, v).

Canals of the Nectophores. — A short peduncular canal (figs. 5, 6, cp) passes from the
top of the siphosome immediately to each nectophore, obliquely ascending in the apical
bell, descending in the basal bell. The peduncular canal runs through the lamellar
pedicle of the nectophore obliquely to the top of the nectosac, and gives off in this
course two vertical blind pallial canals or " mantle-vessels," an ascending and a descending.
The superior or ascending mantle-canal (figs. 2-7, cs) runs vertically upwards towards
the top of the bell, near to the apical edge of its triangular peduncle, and may be
regarded as the homologue of a somatocyst. The inferior or descending mantle-canal
(figs. 2-7, cs') runs in the opposite direction downwards, between the basal edge of the
peduncle and the ventral canal of the nectosac, parallel to the latter. The four canals of
the nectosac, which arise from the distal end of the peduncular canal, are arranged in two
pairs of very different length and form. The ventral (cv) and the dorsal canal (cd) are
nearly equal, and lie in the sagittal plane, foflowing the simple curvature of the nectosac,
whereas the two lateral canals (ex right, and el left) are twice as long as the former, and
form in their course a double sigmoidal loop ; they descend from the top of the nectosac
curved towards the dorsal face, then are bent twice downwards and twice upwards, and
finally reach the circular canal near the ventral face (figs. 2-7).

llydrcecium. — There is no true hydrcecium or funnel cavity in the genus Praya,
but the two deep ventral grooves of the two opposite nectophores, or the funnel-furrows,
(fig. 4a, 4b, ni), are so turned one to another, that there is formed a cylindrical hydrcecial
canal, open at both ends. Its smaller apical half, with the upper aperture, is empty ; its

148 THE VOYAGE OF H.M.S. CHALLENGER.

larger basal half encloses the siphosome, which proceeds through its lower aperture ; the
two halves are separated by the apex of the trunk, from which arise also the pedicles of
the two nectophores (fig. 4b, a ; fig. 7, np). The two ventral wings of the larger basal
nectophore (fig. 4b) embrace the two opposite ventral wings of the smaller apical necto-
phore (fig. 4a) so completely that the lateral sides of the hydrcecial canal are perfectly
closed (fig. 3, apical view).

Siphosome (fig. 1). — The common trunk of the cormus is a cylindrical tube of the
highest contractility, and in the contracted state is very short and partly hidden in the
hydrcecial canal ; in the fully expanded state it attains a length of more than two feet
and offers a splendid aspect, the numerous cormidia (forty to fifty or more) being
separated by equal intervals, each giving off a bright yellow contractile siphon, and a
long tentacle with numerous tentilla, the latter armed with yellow cnidosacs.

Cormidia (PI. XXXII. ). — Each cormidium is a eudoxome, composed of two medusoid
persons, a sterile medusome (siphon with bract and tentacle), and a fertile medusome (the
gonophore). Sometimes two gonophores occur in the same group. The gonophores in
the proximal part of the trunk are usually female, those in the distal part male ; but
sometimes both sexes alternate rather regularly. The cormus is therefore monoecious.
The gonads are very small ; often perhaps they do not become ripe until the Eudoxise
have become detached from the stem, but usually they seem to ripen sessile on the
trunk. Some free-swimming Eudoxise, belonging to the genus Eudoxella (Genus 11a)
are so similar to the sessile Eudoxome of this species of Praya, that I suppose they
have been detached from a species of this genus.

Bract (PI. XXXII. fig. 8, b ; fig. 9).— The bract or hydrophyllium (the umbrella of
the sterile medusome) somewhat repeats the kidney-form of the nectophores. It
attains a length of 10 to 12 mm., a height of 8 to 10 mm. Its jelly-wall is very thick
and soft, mainly in the rounded apical half. The basal half is deeply excavated, and its
thinner-walled cavity, corresponding to the subumbrella (w), encloses the siphon with its
tentacle, and the gonophore. The convex exumbrella is rounded and smooth all round,
and at its basal margin presents three deep sinuses or incisions, two paired lateral and one
odd dorsal (fig. 9). The trunk of the siphosome (fig. 8, a) passes through the two lateral
incisions, while the tentacle (fig. 8, t) steps out through the dorsal incision. Two lateral,
nearly quadrangular lobes, comparable to the two buccal valves of a helmet, are separated
by those sinuses.

Canals of the Bract (figs. 8, c, 9, c) — Each hydrophyllium must be regarded as the
reduced umbrella of a Hydromedusa, and still possesses the four radial canals, char-
acteristic of the latter. A short peduncular canal or apical vessel (figs. 8, 9 ca), goes from
the trunk (a) to the apical part of the subumbrellar cavity, gives off a short spindle-
shaped caecum (phyllocyst), and four divergent, irregularly bent canals, two odd sagittal
and two paired lateral. The odd ventral canals (cv) forms an S-shaped loop in the solid

REPORT ON THE SIPHONOPHOR^. 149

jelly mass of the apical and ventral half of the nectophore. The odd dorsal canal (cd)
runs along the convexity of its basal and dorsal half. The two paired lateral canals (ex
right, cl left) pass into the two lateral lobes or buccal valves of the helmet-shaped bract.
The blind ends of all four canals are somewhat swollen and club-shaped. Their course,
as well as the mode of their apical junction, are very variable, and subject to many
individual abnormalities. Usually the ventral canal is shorter than the dorsal, and the
right shorter than the left.

Siphons (PL XXXI. fig. 1 ; PI. XXXII. fig. 8, s; fig. 11).— The siphon or polypite,
which is attached to the stem at the lateral incision of each bract by a very short pedicle,
exhibits a hemispherical basigaster (sb), the thick wall of which is filled up by cnidoblasts.
The stomach (sh) is ovate and exhibits eight broad yellow hepatic strige (sh). The con-
tractile proboscis (sr) is very muscular and opens through a mouth of very variable form
(so). Sometimes the distal part of the siphon is so invaginated and retracted into the
proximal part, that it assumes the peculiar form shown in fig. 11.

Tentacles (fig. 8, t ; figs. 12-14). — The tentacle, which depends from the short pedicle
of each siphon, is very long and mobile, cylindrical and distinctly articulated, beset with
a series of very numerous tentilla or lateral branches. These arise from the constrictions
between each two segments of the tentacle. Each tentillum (figs. 12-14) contains a
canal, which is somewhat convoluted before entering into the dilated cnidosac (fig. 13).
The latter is reniform or crescentic and contains a strong battery of cnidocysts, six to
eight longitudinal rows of small medial paliform cnidoblasts (km), and on each side (right
and left) a longitudinal series of large sabre-shaped lateral cnidoblasts (kl), eighteen to
twenty-four in each series. Three groups of small pyriform thread-cells (an odd dorsal,
hpi, and two paired ventral, kpn), are found on the base and on both sides of the distal
end of the battery. The terminal filament of the tentillum (tf) forms in the contracted
state three coiled spiral turnings.

Gonophores (fig. 8,h; fig. 10). — -Each cormidium usually exhibits, half hidden under
the bract, a single gonophore, either male or female. It is placed at the ventral side of
the siphon, whilst the tentacle arises from its dorsal side. The umbrella of the gonophore
(fig. 10) is laterally compressed, bilateral, and exhibits two very broad wings in the
sagittal plane ; the dorsal wing (nd) is triangular and nearly as large as the nectosac,
whilst the ventral wing (nv) is much smaller. The nectosac (w) is hemispherical or
campanulate, with a broad velum (v). The peduncular canal enters between the
two wings into the jelly umbrella and gives off at the apex of the nectosac the four radial
canals (cd dorsal, cv ventral, ex right, cl left). The spindle-shaped spermarium (fig. 8, h)
and the ovate or subspherical ovarium (fig. 10,/) are rather small, and in the largest
Eudoxiae only fill the superior half of the subumbrellar cavity.

150 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 25. Lilyopsis,1 Chun, 1885.
Lilyopsis, Chun, Sitzungsb. d. k. Akad. d. "VViss. Berlin, Feb. 5, 1885, p. 18.

Definition. — Diphyidae with two rounded, hemispherical or mitriform, edgeless
uectophores, of similar form and subequal size, opposed to one another. A hydrcecial
canal is formed by the opposite hemicylindrical ventral grooves of the two nectophores.
Bracts hemispherical, mitriform, or reniform. Phyllocyst with (four) radial canals. Each
cormidium with a sterile special nectophore.

The genus Lilyopsis was founded by Chun in 1885 (86) for those Diphyidae, formerly
described as Prayse, which differ from the true Prayse in two important points. The
Eudoxiae of Praya are composed of two persons, a sterile medusome (bract with siphon
and tentacle), and a fertile gonophore. The Eudoxiae of Lilyopsis possess, besides, a third
medusome, a sterile special nectophore, and usually they have a cluster of gonophores
instead of a single fertile medusoid. Lilyopsis, therefore, bears the same relation to
Praya that Diphyopsis has to Diphyes. The special nectophore is in some species of this
genus more medusiform than in any other Siphonanthae. It possesses a circle of
numerous rudimentary tentacles at the margin of the umbrella, and, besides, often a
number of red pigment spots, which may be regarded as ocelli. Lilyopsis agrees in this
respect with the nearly allied Desmophyes (PI. XXX.).

It is probable that in some species of Lilyopsis the cormidia are detached from the
stem, and represent a self-subsistent free-swimming form of Lilsea (Genus 17b).

The first described species of Lilyopsis (1853) is the Mediterranean Praya diphyes
of Vogt (6, Tab. xvi., xvii.) and of Kolliker (4, Taf. ix.). Another Mediterranean species
was figured in 1870 by Metschnikoff under the name Praya medusa, and described
in the Russian language, therefore inaccessible. It is probably the same as that of which
Fewkes published a figure in 1880 (42). A third species, also Mediterranean, was
announced by Chun in 1885 under the name Lilyopsis rosea.2 A fourth species, Lily-
opsis catena, similar to the latter, was observed by me in 1866 in the Canary Island
Lanzerote, but not sufficiently examined.

Subfamily DiphyopsiD/E.

Genus 26. Galeolaria,3 Lesueur, 1807.

Galeolaria, Blainville, Manuel dActinologie, 1834, p. 139.

Definition. — Diphyidae with two angular slenderly pyramidal nectophores of similar

form and subequal size, one placed behind the other. First nectophore without

hydrcecium. Cormidia without special nectophores. Bracts conical or spathiform, with

a pointed apex. Phyllocyst small or rudimentary, without radial canals.

1 Lilyopsis = Similar to a lily. ! 86, p. 18, Taf. ii. figs. 12, 13.

3 Galeolaria = Provided with small helmets, galeola.

REPORT ON THE SIPHONOPHOR^E. 151

The genus Galeolaria (confounded by later authors with Epibulia) was founded in
1807 by Lesueur, in a manuscript not published, for two Australian Diphyes, which were
figured by Quoy and Gaimard under the names Galeolaria australis and Galeolaria
quadridentata (2, pi. v. figs. 30-33). The same were afterwards regarded by Blainville as
the types of this genus (24, p. 139). The first accurate description of two Atlantic
species belonging to it was published in 1846 by Sars (under the names Diphyes truncata
and Diphyes biloba (27, p. 41, Taf. vii.). A Mediterranean species was accurately
described by Gegenbaur as Diphyes turgida (68), and another by Vogt as Epibulia
aurantiaca (6). An Arctic Galeolaria, inhabiting the Greenland Sea, is Diphyes sarsii
of Gegenbaur (10, Tab. xxx. figs. 30, 31). The Iudian Galeolaria fil ij brmis described by
Huxley (9, pi. iii. fig. 5) is probably identical with the original Galeolaria australis of
Lesueur. Different from all these species is the Galeolaria stephanomia, inhabiting the
Tropical Pacific, described by Brandt as Diphyes stephanomia (25, p. 32). I was able to
compare the excellent figure and description of it (unfortunately not published !) which
Martens had taken from nature as early as 1827.

Galeolaria (synonymous with Sulculeolaria of Blainville) differs from Diphyes in the
complete absence of a hydrcecium. The basal part of the truncate ventral side of the
first nectophore is simply attached to the corresponding apical part of the second.
Between them the siphosome depends freely. The nectocalycine ducts are therefore very
different in the two nectophores, entering into the first at its base, into the second at its
apex. The ventral radial canal is very short in the first, very long in the second necto-
phore. The ventral plate of the umbrella is prolonged in both nectophores over their
basal ostium in the form of a bilobate lamellar apophysis (compare Leuckart, 8, p. 279,
and Huxley, 9, p. 38). The gonophores ripen on the stem, and are not detached as free-
swimming Eudoxise. The conns are dioecious (p. 99).

Genus 27. Diphyes,1 Cuvier, 1817 (sensu restricto).
Diphyes, Cuvier, Le Regne animal, t. iv. p. 61.

Definition. — Diphyidse with two angular, slenderly pyramidal nectophores, of similar
form and subequal size, one placed behind the other. First nectophore with a conical or
campanulate hydrcecium. Cormidia without special nectophores (free as Cucullus, Genus
12). Bracts pyramidal, conical, or spathiform, with a pointed apex. Phyllocyst simple,
usually large and ovate, without radial canals.

The genus Diphyes was founded by Cuvier in 1817 upon the first figure published of
any Calyconecta, the Diphyes dispar of Chamisso (16), which was figured first by Bory
in 1804 under the name Biphora bipartita (13, p. 134). Eschscholtz gave in 1829 a
more accurate description of Diphyes, and the following definition : — " Ductus nutritorius

1 Diphyes = Double animal (oifvvis) ; Calyconecta with a double nectophore.

152 THE VOYAGE OF H.M.S. CHALLENGER.

tubulis pluribus obsitus. Tubuli squarnis cartilagineis obtecti. Pars corporis nutritoria
cavitate natatoria interna, extrorsum se aperiente instructa," He distinguished four
different species, the fourth of which, Diphyes appendiculata, from the Pacific Ocean, is
here retained as the representative type of the genus (1, p. 138, Taf. xii. fig. 7). Nearly
allied to this are two Mediterranean species, Diphyes acuminata of Leuckart (5), and
Diphyes sieboldii of Kolliker (4). A third Mediterranean species is Diphyes subtilis of
Chun (87). Different from these is Diphyes elongata, Hyndman, from the northern
Atlantic (64), and an Indian species, Diphyes gracilis. Huxley united all these species
under the name Diphyes appendiculata; there seem to be, however, constant differ-
ences between these species, which may be considered as specific, the more so as they are
inhabitants of widely distant seas. A more accurate distinction is required.

Gegenbaur, in 1859, distinguished not less than ten different species of the genus
Diphyes (10, p. 50) ; the majority of these belong, however, to other genera of Dipkyidas,
Diphyopsis {Diphyes campanulifera, &c), and Galeolaria (Epibidia quadrivalvis, &c).

The cormidia of Diphyes (in the sense here restricted) possess a spathiform or three-
sided pyramidal bract, with a deep ventral fissure, and become mature as free Eudoxise
belonging to the genus Cucullus (compare above, Genus 12).

Genus 28. Diphyopsis,1 Haeckel, 1888.
Diphyopsis, Hkl., System der Siphonophoren, p. 35.

Definition. — Diphyidse with two angular, slenderly pyramidal nectophores of similar
form and subequal size, one placed behind the other. First nectophore with a conical
or campanulate hydroecium. Each cormidium with a special nectophore (free as Erssea,
Genus 17b). Bracts pyramidal, conical or spathiform, with a pointed apex. Phyllocyst
simple, ovate, without radial canals.

The genus Diphyopsis comprises those Diphyidse hitherto described as Diphyes,
which differ from the true Diphyes in the possession of numerous special nectophores,
each of which is the locomotive organ of a cormidium, swimming free as Erssea (compare
above, Genus 17). Diphyopsis bears the same relation to Diphyes that Lilyopsis has to
Praya. The special nectophore of each cormidium (wanting in Diphyes) is the originally
first gonophore, which has lost its sexual function, and produces no manubrium ; it is
subservient only to locomotion.

The first described species of Diphyopsis is Diphyes dispar of Chamisso and Eysen-
hardt, inhabiting the Tropical and Southern Pacific (16, p. 365, Tab. xxxiii. fig. 4). A
very accurate description of it was given by Huxley (9, p. 30, pi. i. fig. 1). Probably
identical with it is Diphyes angustata of Eschscholtz. The Challenger collection con-

1 Biphyopds = Similar to Diphyes.

REPORT ON THE SJPHONOPIIORvE. 153

tains specimens of this species, taken in different parts of the Pacific {e.g., Stations 175,
222, 265 to 279, &c).

A second species may be the Mediterranean Diphyopsis campanulifera, described as
Diphyes campanulifera by Eschscholtz, first observed by Quoy and Gaimard in the
Strait of Gibraltar.

A third species is described in the following lines as Diphyopsis compressa. It
inhabits the Tropical and Subtropical Atlantic. The Challenger collection contains many
specimens of it, taken between Stations 327 and 353.

Diphyopsis compressa, n. sp. (Pis. XXXIIL, XXXIV.).

Diphyes compressa, Hkl., 1866, MS. Canar.
Habitat.— Tropical and Subtropical Atlantic, Stations 327, 334, 348, 352a.
Canary Islands, Lanzerote, December 1866 (Haeckel).

Nectophores (fig. 1, the two nectocalyces in their natural connection, seen from the
left side ; fig. 2, from the ventral side ; fig. 3, from the dorsal side). — The two large
swimming bells are of nearly equal size and similar form ; their usual length is between
25 and 30 mm., the breadth between 10 and 15 mm., the thickness 5 to 7 mm. ; the
first or apical nectophore, however, is a little larger, longer as well as thicker, than
the distal one. The former encloses on its ventral side a campanulate hydrcecium
(and above its top a somatocyst) ; the latter an incomplete subcylindrical hydrcecial
canal.

Apical Nectophore. — The first, superior, anterior or proximal nectocalyx, appears in
the lateral view (fig. 1) as a broad triangle, the dorsal side of which (nd) is the longest
and slightly convex ; the opposite ventral side (nv) is more convex, one-fifth shorter, and
twice as long as the obliquely bevelled basal side. The ratio of the three sides therefore
is = 5:4:2. Seen from the ventral side (fig. 2), or from the dorsal side (fig. 3), the
nectophore appears as a very long and narrow isosceles triangle, the two equal lateral
sides of which are four times as long as the basal side. Seen from the basal face (fig. 8) it
appears nearly rectangular, three times as long as broad, with a small triangle imposed on
the dorsal side. The exumbrella therefore has the form of a bilateral pentagonal pyramid,
which is very strongly compressed from both sides. Its surface exhibits five prominent
ridges, one odd dorsal and two pairs of laterals, meeting in the slender pointed top of the
nectophore. The odd dorsal ridge (figs. 1, 3, nd) runs in the median dorsal line of the
exumbrella and ends below in the odd dorsal tooth of the mouth of the nectosac. The
two dorsodateral ridges run along the lateral faces of the nectosac and end below in the
smaller dorso-lateral teeth of its mouth (n1, n2). The two ventro-lateral ridges run along
the ventral face of the hydrcecium and end in two small ventral teeth (fig. 8, nB n6e)

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hllhll 20

154 THE VOYAGE OF H.M.S. CHALLENGER.

Between the former and the latter pair of ridges there arise in the basal third of the
exumbrella two convergent incomplete medio-lateral ridges, which end in the two large
ventro-lateral teeth of the nectosac mouth (n3, n4). The five teeth of the mouth and
the basal parts of the ridges are elegantly denticulate.

Nectosac (figs. 1-3, w). — The umbrellar cavity of the first nectophore is nearly
cylindrical, conical above, and in the contracted state four to six times as long as broad.
It occupies two-thirds of the length of the umbrella, and is placed in its dorsal half, close
to the ventral hydrcecium. From the top of the nectosac arises a long tubular csecum,
or a vertical apical canal (figs. 1, 2, cp) ; its blind end nearly reaches the outmost apex
of the umbrella. The nectocalycine duct (or the peduncular canal of the first nectophore)
descends from the top of the trunk obliquely towards the ventral side of the nectosac and
enters into it at a point between the first and second third of its height. It divides here
into the four radial canals of the nectosac. The shortest of these is the straight ventral,
the longest is the loop-shaped dorsal canal. The two lateral canals are shorter than the
latter, longer than the former, ascend like the dorsal, and then descend beyond the apex.

Mouth of the Nectosac (fig. 1, lateral view; figs. 3 and 7, dorsal view; figs. 6 and 8,
basal view). The basal opening of the subumbrella is rather narrow, with a broad velum
(v), and protected by five convergent teeth, the ends of tbe above-mentioned longitudinal
ridges. The odd dorsal tooth (nd) and the two dorso-lateral teeth (n1, n~) are of nearly
equal size, half as large as the two ventro-lateral teeth (n3, n4).

Hydrcecium (fig. 1, id, lateral view ; fig. 2, ui, ventral view). — The funnel-cavity of
the first nectophore, or the hydrcecium, occupies the basal half of its ventral side. It is
slenderly campanulate and two-thirds as long as the nectosac, which is placed closely at
its dorsal side. The ventral half of the hydrcecium includes the peduncle or the apical
apophysis of the second nectophore (np), the dorsal half the upper part of the siphosome.
The basal mouth of the hydrcecium (fig. 8) is rectangular, three times as long as broad,
and armed with four pointed teeth, two ventral (n5, n6), and two dorsal (ns, n*) ; the
latter are the ventro-lateral teeth of the nectosac-mouth.

Somatocyst (figs. 1, 2, cs). — The acrocyst or the coryphal cavity of the first necto-
phore is a spindle-shaped or subcylindrical csecal canal, half as long as the hydrcecium.
It arises vertically from the top of the latter and extends over the top of the nectosac,
about as far as the basal half of its apical caecum.

Basal Nectophore (figs. 1 and 4 seen from its right side, figs. 3 and 5 from the
ventral side). — The second, inferior, posterior or distal nectocalyx, is of the same length
as the apical nectophore, but not so broad. The form of its dorsal half (with the nectosac
and the quinque-dentate ostium) is very similar to that of the former ; but it has no
somatocyst, and the form of the ventral half and the apex are very different. The apical
part, above the nectosac, is nearly as long as the latter, isosceles triangular, and
elongated into a pointed apophysis, which is completely received within the hydrcecium

REPORT ON THE SIPHONOPHORJE. 155

of the first nectophore. Along its dorsal side runs the nectocalycine duct or pedicular
canal (cp), which opens at the apex into the top of the stem.

Hydrcecial Canal. — Whilst the dorsal half of the basal nectophore is occupied by the
slender, cylindrical, slightly curved nectosac, its ventral half is occupied by the hydrcecial
canal (nf). This is an open groove in the greater part of its length, limited by two
\ riitro-lateral wings of the umbrella ; but in the middle part (opposite to the superior
third of the nectosac) the two wings have grown together and form a complete canal
(figs. 4, 5 nb,), and in the inferior third the broader left wing (nl) overlaps the smaller
right wing (nx). The five denticulate edges of the second nectophore and the five basal
teeth around the mouth correspond to those of the first.

Siphosome (fig. 1, a).— The common stem of the body is a very long and slender
tubule in the expanded state, four to six times as long as the nectophores. It is enclosed
in the hydrcecial canal of the basal nectophore, is attached at the apex to the top of the
hydrcecium of the apical nectophore, and is here directly prolonged into the somatocyst
of the latter (cs). Whilst a great part of the siphosome can be retracted into the
hydrcecial canal when contracted perfectly, it can be widely prominent by its lower
aperture when expanded.

Cormidia. — The eudoxomes, which beset the whole stem at regular intervals (about
equal to their lengths) are very numerous, in large specimens sixty to ninety, or more
(fig. 1 ). They have a spathiform bract, which is prolonged above its insertion upwards
into a cowl (PI. XXXIV. figs. 9, 11). This cowl is open at the ventral side, and con-
tains a spindle-shaped phyllocyst (cs), which encloses in its apex an oleocyst (co). The
ventral side of the bract is opened by a deep fissure, and its base obliquely bevelled,
and armed with four short triangular teeth ; the two dorsal teeth are larger than the two
ventral.

The cavity of the bract encloses a cylindrical siphon with a long tentacle, and besides
a large special nectophore, and one or two, rarely three, gonophores. These are brought
to maturity after the eudoxome has been detached from the stem. It then swims
freely about as Erssea compressa (compare the description of this genus, pp. 122-124,
and PI. XXXIV.).

Subfamily Abylid.-e.

Genus 29. Abyla,1 Quoy et Gaimard, 1827.

Abyla, Quoy et Gaimard, Ann. d. Sci. Nat. (Zool.), t. x.

Definition. — Diphyidas with two angular, pyramidal or prismatic nectophores of
different size and form. The basal nectophore is three-sided-pyramidal, asymmetrical,
and much larger than the symmetrical apical nectophore. Bracts six-sided-prismatic, with

1 Abyla = Aflfax, the southern column of Hercules, opposite to Calpe, Strait of Gibraltar.

156 THE VOYAGE OF H.M.S. CHALLENGER.

a vertically descending phyllocyst, and two lateral, horizontally diverging canals, arising
from its apex {Amphiroa, Genus 14).

The genus Abyla was founded by Quoy and Gaimard (1827, 20) for the Mediterranean
Abyla trigona, observed by them in the Strait of Gibraltar. I retain this species as
the characteristic type of the genus, sensu strictiori. The majority of later authors have
united with this typical species the very different Diphyidae which belong to the two
following genera, Bassia and Calpe. But the characteristic form of the nectophores, as
well as of the bracts, justifies the separation of these three genera of Abylidse. The large
distal or inferior nectophore is trigonal in Abyla, tetragonal in Bassia, and pentagonal
in Calpe. The polyhedral form of the hydropbyllia or bracts, too, exhibits characteristic
differences in the three genera, and their phyllocysts give off two horizontal lateral
canals in Abyla, one odd descending canal in Bassia, and four canals (one ascending,
one descending, and two lateral) in Calpe. The free Eudoxia of the first genus is
Amphiroa, of the second Sphenoides, and of the third Aglaisma.

The new species of Abyla, here described as Abyla carina, differs as wTell from the
well-known Mediterranean Abyla trigona, very accurately described by Gegenbaur (10,
Taf. i., ii.), as from the species inhabiting the Tropical Pacific which Huxley has described
under the same name (9, pi. iii., fig. 1) ; I call this latter Abyla alata. Different from
these is Abyla leuckarti of Huxley (9, pi. iii fig. 2), inhabiting the Southern Pacific.
I observed myself Abyla carina in 1867 in the Canary Island Lanzerote, and made there
the drawings reproduced on Pis. XXXV. and XXXVI. from the living specimen. The
same species occurred in a bottle in the Challenger collection, taken at Station 34S.

Abyla carina, n. sp. (Pis. XXXV., XXXVL).

Habitat. — Tropical and Subtropical Atlantic; Station 348 ; April 9. 1876.
Coast of Sierra Leone, lat. 3° 10' N., long. 14° 51' W. Surface.
Canary Islands, Lanzerote, February 1867 (Haeckel).

Nectophores. — The two nectocalyces united are 35 to 40 mm. long ; they are very
different in form and size. The distal or posterior nectophore is 25 to 30 mm. long and
12 to 14 mm. broad, about twice as large as the proximal or anterior, the length of which
is 10 to 12 mm., the breadth 7 to 8 mm. The ground-form of the smaller is symme-
trical, of the larger asymmetrical.

Apical Nectophore (fig. 3, apical view, from above ; fig. 4, basal view, from below ;
fig. 1 and fig. 5, lateral view, from the left side ; fig. 6, ventral view ; fig. 7, dorsal
view). — The first nectophore (the proximal, anterior, superior or apical nectocalyx) is a
hexagonal prism of a completely symmetrical bilateral ground-form. When the axis of
the nectosac stands vertically (as in figs. 5-7), then the .six lateral faces of the prism

REPORT ON THE SIPHONOPHOR^E. 157

are also nearly vertical ; whilst the two terminal faces (superior and inferior) bear a
pyramidal apophysis.

The six lateral faces are two odd and four paired. The dorsal odd face (fig. 7) covers
the nectosac, and is nearly rectangular, twice as long as broad, its superior edge a
little longer than the inferior. The opposite ventral odd face, covering the somatocyst
(fig. 6, uv) is smaller, isosceles triangular, three times as long as broad ; the apex of the
triangle is directed downwards, the two lateral edges are convex. The two paired ventro-
lateral faces (fig. 5, cs) are Cjuadrangular, their dorsal edge longer than the parallel ventral,
and the straight superior edge smaller than the concave inferior. The two paired dorso-
lateral faces cover the lateral sides of the nectosac (fig. 5, w), and are hexagonal ; their
two parallel, nearly vertical, lateral edges are two to three times as long as each of the
two superior or the two inferior edges.

The apical or superior face (fig. 3) of the hexagonal prism is not a simple face, but
divided by a prominent transverse frontal crest (fig. 3, ut) into two unequal apical facets,
a dorsal and a ventral. The dorsal apical facet is far larger, and covers the apex of the
nectosac (fig. 3, iv1) ; it is hexagonal, with two odd and four paired edges ; the odd dorsal
and ventral edges (ut) are parallel and of equal length ; they are longer than the two
ventro-lateral, and smaller than the two dorso-lateral, deeply emarginated edges.

The ventral apical facet is quadrangular, much smaller, and covers the top of the
somatocyst (fig. 3, cs). Its two lateral edges are twice as long as the inferior and
superior edge (fig. 3, ut), and are so deeply emarginated that the facet appears to be
nearly bisected by a frontal constriction.

The basal face of the hexagonal prism (fig. 4) is also divided by a prominent transverse
frontal crest into two unequal basal facets, a dorsal and a ventral. The dorsal basal facet
is square, and contains the opening of the nectosac (fig. 4, iv1). The ventral basal facet
contains the opening of the hydrcecium (fig. 4, ui), and is isosceles triangular ; the apex
of the triangle is directed ventrally, and meets with the apex of the triangular ventral
face (fig. 6, cs).

The interior of the first nectophore contains the nectosac (to) in its dorsal third, the
somatocyst (cs) in its ventral third, and between both the hydrcecium (ui) in the middle
third. The longitudinal axes of these three organs are nearly parallel, a little con-
vergent towards the apex (fig. 5).

Nectosac (figs. 1 and 5, w, from the right side ; fig. 7, w, from the dorsal ; fig. 3,
from the apical ; fig. 4, from the basal side). — The subumbrella is subcylindrical, four times
as long as broad ; it occupies the dorsal third of the first nectophore, and is separated by
a very thin frontal septum from the adjacent hydrcecium. The nectocalycine duct is
very short, and enters into the bent apex of the nectosac, so that the four radial canals
of the latter are very regular, and of nearly equal length. The basal opening of the
nectosac is very small, and surrounded by a small velum (fig. 4, v).

158 THE VOYAGE OF H.M.S. CHALLENGER.

Hydrcecium (figs. 1, 5, ui, from the right side; fig. 4, from below). The infundi-
bulum of the first nectophore, or the hydrceciurn, occupies its middle third, and is larger
than both the nectosac (w) at its dorsal, and the somatocyst (cs) at its ventral side. It
is slenderly campanulate or conical, in the superior half rather cylindrical, in the inferior
much dilated. Its blind apex reaches nearly the frontal crest of the apical face. Its
basal opening is isosceles triangular (fig. 4, ui) ; the base of the triangle is formed
by the prominent frontal septum, whilst the apex meets with the inferior apex of the
triangular ventral face of the nectophore.

Somatocyst (figs. 1, 5, cs, lateral view; fig. 6, cs, ventral view). — The somatocyst is a
very large cylindrical sac, and occupies the ventral third of the first nectophore. Its
cavity is nearly filled with large vacuolated polyhedral entoderm -cells. It is separated
by a thin septum from the ventral wall of the hydroecium. A short bent canal connects
its apex with the top of the common stem.

Basal Nectophore (figs. 1, 9, lateral view from the left side ; fig. 10, distal part from
the right side ; fig. 8, ventral view ; fig. 11, basal view). — The second nectophore (the
distal, inferior, or basal nectocalyx) is about twice as long and broad as the first, and has
in general the form of an asymmetrical pentagonal pyramid ; but three of its five
edges are far more developed than the other two, so that the general appearance of
the irregular pyramid is more trigonal. Its apex is a curved conical condyle, its base
rounded.

The five edges of the basal nectophore, one odd dorsal and four paired, corresponding
to those of Dipliyes and Calpe, are developed in a different manner ; the largest and
most prominent wing is the right ventro-lateral edge (nx), and next to it the obliquely
opposed left dorso-lateral edge (n1). The odd dorsal edge (nd) is of intermediate size.
The left ventro-lateral edge (nl) is short and broad in the middle part ; the right dorso-
lateral edge is the smallest, and more rudimentary.

The hydrcecial canal of the second nectophore is an open groove on its ventral side,
protected by the two broad ventro-lateral wings, the right of which (nx) is much larger
and overlaps the left (nl). The shorter left wing is prominent as a vertical triangular
plate, the inferior part of which is broad and its margin strongly dentate (figs. 8, 9, nl).
The larger overlapping right wing (nx) is more crescentic, and has a convex dentate
margin, which is much thickened in the inferior third ; the free basal edge of this
thickened margin bears two parallel rows of teeth ; the right row (nx") is somewhat larger
than the left (nx', figs. 8 11).

The apical condyle of the triangular pyramid (figs. 8, 9, nq) on the articular apophysis
of the second nectophore, which fits into the hydrcecium of the first and connects them,
is curved and beak-shaped ; it contains on its concave ventral side a deep hydrcecial
groove, in its convex dorsal part the nectocalycine duct (en).

The base of the second nectophore, seen from below (fig. 11), offers a very peculiar

REPORT ON THE SIPHONOPHOR^E. 159

aspect, distinguishing the genus Abyla at once from the other Abyliche. Its outline is
irregularly triangular, and its sagittal axis (vertical in fig. 11) one and a half times as
long as the frontal (horizontal) axis. The three more prominent wings are so turned in
the inferior part that the basal edge of the right ventro-lateral wing (nx) occupies the
ventral half of the sagittal axis, and is just opposed to the dorsal wing (nd). The left
dorso-lateral wing (n1), on the other side, occupies the left half of the frontal axis.
The five strong denticulate teeth, which form the basal ends of the five lateral wings, are
so turned that the basal mouth of the second nectophore, beyond the ostium of the
nectosac, forms a broad transverse or frontal fissure (like the mouth of a Plagiostome),
and perpendicular to this is a larger ovate longitudinal fissure (in the dorsal half of the
sagittal axis).

Nectosac (figs. 8-10, ur). — The subumbrella of the second nectophore is very long,
subcylindrical, about six times as long as broad. Its apex touches the base of the
apical condyle (nq) and receives the nectocalycine duct (en), which passes through the
latter. The four radial canals of the subumbrella are regularly disposed, and united by
a small velum at its basal opening (fig. 11, uo). This opening is strongly protected and
partly hidden by the five basal teeth proceeding from the five wings of the exumbrella,
and described above (fig. 11).

Siphosome. — The common stem, when contracted, is completely hidden in the
hydrcecial canal described above. When the animal floats quietly on the surface of the
tranquil sea it offers the peculiar aspect figured in figs. 1 and 2, PI. XXXV., which I
drew from a living, intact specimen, 11th February 1867, in the Canary Island Lanzerote.
The longitudinal axis of the body (marked by the straight bne of the expanded stem, on
the dorsal median line of the hydrcecial canal) is so inclined that it cuts the horizontal
level of the sea at an angle of 20°. The level is touched by the most prominent dorsal
parts of the body, the frontal crest of the first nectophore, and the uppermost part of the
dorsal edge of the second. A bunch of fishing tentacles issues through the basal opening
of the hydrcecial canal.

Cormidia. — The Eudoxise attached to the siphosome, forty to sixty or more, are
regularly arranged in the usual ordinate manner, and do not reach sexual maturity before
being detached from the common stem. After being detached, they swim freely about
as Eudoxise, which assume the characteristic form of Amphiroa carina described above
(Genus 16). They are distinguished from other Eudoxidse by the six-sided prismatic
bract, with its large vertically descending dorsal phyllocyst, and the two horizontal
lateral canals arising perpendicularly from its uppermost apex (compare p. 114 and
PL XXXVI.).

100 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 30. Bassia,1 Quoy et Gaimard, 1827.
Bassia, Quoy et Gaimard, MS. (compare Lesson, Aealephes, p. 451).

Definition. — Diphyidse with two angular, pyramidal or prismatic nectophores of
different size and form. The basal nectophore is four-sided pyramidal, asymmetrical, and
much larger than the symmetrical apical nectophore. Bracts, four-sided prismatic and
wedge-shaped below, with an ovate, ascending phyllocyst, and an odd descending canal
arising from its base (Sphenoides, Genus 15).

The genus Bassia was founded by Quoy and Gaimard in 1827 for a Diphyid which
they found in Bass Strait, and called, from its four-sided nectophore, Bassia quadri-
latera. The majority of later authors have called it Abyla quadrilatera (following
Blainville, 24), or Abyla bassensis, following Huxley, who gave an excellent description
of it in 1859 (9, p. 45). Another species, from the Tropical Atlantic, taken oif the coast
of Guinea, was described at the same time very accurately by Gegenbaur under the name
Abyla perforata (10, p. 26, figs. 20, 21). I myself have observed a third species in the
Indian Ocean (Bassia tetragona), and a fourth species, different from the three others,
in the Canary Islands, Bassia obeliscus. Since the latter also occurs in a bottle in the
Challenger collection, taken in the Northern Atlantic, near the Azores (Station 354,
May 6, 1876), I give its special description here, and the figures which I drew in 1867
from living sjjecimens in Lanzerote. Bassia differs from Abyla (with trigonal necto-
phore) and Calpe (with pentagonal nectophore) in the tetragonal shape of its distal
nectophore, which retains better the original form of a quadrilateral Medusa-umbrella. It
differs further in the peculiar form of its wedge-shaped hydrophyllia and Eudoxire, which
are free Sphenoides (p. 116) with an odd basal canal descending from the phyllocyst.

Bassia obeliscus, n. sp. (Pis. XXXVII., XXXVIIL).

Abyla obeliscus, Hkl., 1867, MS. Canar.

Habitat. — Northern Atlantic ; Station 354, south of the Azores, west of the Canary
Islands, May 6, 1876 ; hit. 32° 41' N, long. 36° 6' W. Surface.
Canary Islands, Lanzerote, February 1867 (Haeckel).

Nectophores. — The two nectophores united are 12 to 16 mm. long, 5 to 7 mm.
broad ; they are very different in form and size. The distal or posterior nectophore is
10 to 12 mm. long, 5 to 7 mm. broad; twice as long and broad as the proximal or
anterior. The ground-form of the latter is symmetrical, that of the former asymmetrical.

Apical Nectophore (fig. 5 seen from the ventral face, fig. 6 from the dorsal face,
fig. 7 from the coryphal edge or the original top, fig. 8 from the basal face). — The apical

1 Bassia= Inhabitant of Bass Strait.

REPORT ON THE SIPHONOPHOR^E. 161

nectophore (first, superior or proximal nectocalyx) has the form of a pentagonal prism.
Its main axis is 5 mm. long, lies in the natural position of the vertical cormus (figs. 1-4)
nearly horizontally, and is therefore perpendicular to the vertical main axis of the large
basal nectophore. The latter is three times as long as the former. The length of the
main axis of the apical nectophore equals the sagittal diameter of the basal nectophore.

The dorsal face of the apical nectophore (fig. 6) is pentagonal, and in the natural
position of the vertically standing cormus directed upwards (fig. 1-3, ud). Seen from
above (fig. 6) the somatocyst (cs) and the nectosac (w) are visible through the trans-
parent dorsal face. The ventral face (fig. 5) is heptagonal, in the natural position
(figs. 1-4) directed downwards, and bisected by a horizontal transverse crest. The apical
half of the bisected face is pentagonal, slightly concave, and through it appears the
somatocyst (fig. 5, cs), whereas the basal half is excavated, and contains the campanulate
hydrcecium (fig. 5, ui), in the fundus of which the siphosome arises. The basal face of
the apical nectophore (fig. 8) is scpuare with four equal concave edges, and in its centre is
placed the aperture of the nectosac (uo). The remaining four faces are two basi-laterals
and two apici-laterals ; the former are pentagonal, the latter tetragonal ; and these two
are separated by the coryphal crest or sagittal edge (nh).

The Nectosac of the Apical Nectophore (fig. 6, w ; fig. 8, iv) is ovate and occupies its
basal half. Its circular basal aperture (fig. 8, uo) is small and surrounded by a broad
velum (v), and a circular canal (cc). The four radial canals of the subumbrella, which
discharge into the latter, are of unequal length ; the ventral canal (cv), near the
hydrcecium, being shorter, the dorsal canal (fig. 6, cd) longer than the two curved lateral
canals {ex right, cl left). The four radial canals unite in the apex of the nectosac, which
is united by a very short peduncular canal with the apex of the siphosome.

Somatocyst (figs. 1, 2, 5, 6, 7, cs). — The somatocyst is subglobular, or spheroidal,
with slightly shortened main axis. It occupies the apical half of the proximal nectophore
and is nearly filled with large polyhedral entoderm cells, so that its central cavity is very
small. It is everywhere surrounded by the thick jelly-mass of the umbrella, and only at
its base in contact with the apex of the nectosac (fig. 6, w) and with the meeting apex of
the hydrcecium (fig. 5, ui) and the siphosome.

Hydrcecium (fig. 1, ui; fig. 5, ui). — The hydrcecium or the funnel-cavity is campanu-
late or obliquely conical, and its wide quadrangular mouth occupies the basal half of the
ventral face of the apical nectophore. The main axis of the hydrcecium is obliquely
inclined, and in the normal position (figs. 1, 2) directed from above and behind downwards
and forwards. The apex of the hydrcecium is the common central point, in which
the somatocyst meets with the peduncular canal of the apical nectophore and the apex
of the siphosome.

The Based Nectophore (figs. 1-4), or the distal nectocalyx, has in general the form of
an obelisk, or of a truncated four-sided pyramid. Its main axis is vertical in the normal

(ZOOL. CHALL. EXP. — PART LXXY1I. — 1888.) Hhbh 21

1G2 THE VOYAGE OF H.M.S. CHALLENGER.

position, and therefore perpendicular to the horizonal main axis of the smaller apical
pneumatophore. The truncated apical or upper face, where it unites with the latter
(fig. 10), exhibits a short condyle or apical apophysis, is deeply notched, and presents a
sort of articular face, into which the solid angle of the apical nectophore, formed by the
junction of its two ventral faces, is received. The siphosome (fig. 10, a) enters through
the apical apophysis into the hydrcecial canal (m).

The opposite basal face of the basal nectophore (fig. 9), or the base of the obelisk, is
nearly rectangular ; its sagittal diameter is twice as great as its frontal axis. The centre
of the dorsal half of the basal face is occupied by the small aperture of the nectosac,
which is surrounded by a broad velum (y) and the circular canal, whereas the ventral
half of the basal face contains the wide opening of the funnel canal (id) through which
the trunk (a) proceeds. The four corners of the basal face are somewhat asymmetrical
and project downward as irregular three-sided pyramids ; the two dorsal corners are
smaller than the two ventral ; the right dorsal corner (w3) is the smallest, and the right
ventral corner (u1) the largest.

The four lateral faces of the basal nectophore (standing vertically in figs. 1-4) are
nearly rectangular, slightly concave, and separated by four prominent, finely serrated
edges. The nectosac is seen through the dorsal face (fig. 4, w), the hydrcecial canal with
the included siphosome through the ventral face (fig. 3, a). This latter is bisected in
the basal half by the hydrcecial fissure ; a broad dentate plate stretching from the right
ventral ridge (ul) over the smaller opposite plate, which arises from the left ventral
ridge (u2). These two ventrolateral crests are stronger and project more downwards
over the basal face than the two dorso-lateral crests ; the right of these (u3) is some-
what larger than the left (m4). The four interraclial crests are not rectilinear, but
slightly curved, S-shaped, and turned a little spirally around the vertical main axis.

The Nectosac of the Basal Necto])hore (figs. 1-4, iv) is slenderly ovate and occupies its
dorsal half. It is twice as broad and three times as long as the nectosac of the apical
nectophore. The dorsal face is more strongly vaulted than the ventral. The circular
basal aperture is small and surrounded by a broad velum (v). The four radial canals of
the subumbrella, which discharge into the circular canal, are of unequal length ; the ventral
(cv) is shorter, the dorsal (ccl) longer than the two curved lateral canals (ex right, el left).
The four canals do not meet in the apex of the nectosac, but a little beyond it on the
ventral face ; and from their meeting point arises a rather long peduncular canal, which
ascends nearly vertically, pierces the articular apophysis of the upper face of the nectosac,
and unites at its apex with the top of the siphosome (figs. 1, 10).

The Hydrcecial Canal occupies the half of the basal nectophore ; it is rather narrow,
subcylindrical, and is separated by a thin jelty-plate from the ventral side of the neigh-
bouring nectosac. Its apical opening (fig. 10) is obliquely truncate, ovate, and opens
into the apical dorsal part of the apical nectophore (fig. 1). Its basal opening (fig. 9, ui)

REPORT ON THE SIPHON OPHOR^E. 163

is far larger and subcircular. The ventral margin of the latter is cleft in its middle ; the
large dentate plate arising from the right ventral crest of the basal nectophore here
covers, like a valve, the free margin of the smaller plate which arises from the opposite
left crest (figs. 3, 9, uk).

The Siphosome, which arises in the apex of the hydrcecium of the apical nectosac,
enters into the hydroecial canal of the basal nectosac by its apical aperture, runs through
it along the ventral face of the nectosac, and proceeds freely through its basal aperture
(fig. 1). In its contracted state, however, the retracted siphosome is completely hidden
in the hydroecial canal (fig. 2).

Cormidia. — The numerous cormidia, which are attached to the stem of the siphosome,
are separated by regular free internodes, and become mature in the form of free Eudoxiae,
which belong to the monogastric genus Sphenoides (compare Genus 15 and PL XXXYIIL).
These are characterised by the peculiar wedge-form of their bracts, and mainly by
the odd spur-shaped dorsal canal, which descends from the base of the large ovate
phyllocyst downwards.

Genus 31. Calpe,1 Quoy et Gaimard, 1827.
Calpe, Quoy et Gaimard, Ann. d. Sci. Nat., 1827, t. x. p. 11.

Definition. — Diphyiclse with two angular, pyramidal or prismatic nectophores of
different size and unequal form. The basal nectophore is five-sided pyramidal, asym-
metrical, and much larger than the symmetrical apical nectophore. Bracts cuboidal,
with a five-sided pyramidal apophysis, and a vesicular phyllocyst, from the base of which
four canals arise, two slender odd sagittal and two broader paired lateral canals
(Aglaisma, Genus 16).

The genus Calpe was founded by Quoy and Gaimard in 1827 for the well-known
Mediterranean species Calpe pentagona. Eschscholtz (1, p. 132), and the majority of
later authors, have described this striking form under the name Abyla pentagon//
(Kolliker 4, Leuckart 5, Huxley 9, Gegenbaur 10, &c). But, besides the other char-
acters, the pentagonal form of the distal nectophore distinguishes the true Calpe at once
from the trigonal Abyla and the tetragonal Bassia, and stdl more the different form of
the bracts in these three genera of Abylidae. The phyllocyst of the true Calpe gives off
four radial canals, two of which are odd and slender (an ascending and a descending),
and two others paired and lateral. The free Eudoxia belongs to the monoirastric senus
Aglaisma (Genus 16). It was in this genus that Leuckart (5) and Gegenbaur (7), both
independently, at the same time, observed the detachment of free Eudoxiae from the
Diphyid corm (compare above, p. 90).

The new species of Calpe, described in the following as Calpe gegenbauri, inhabits

1 Calpe = ~\jTn, KaA^n; also the northern column of Hercules, opposite to Abyla, Strait of Gibraltar.

164 THE VOYAGE OF H.M.S. CHALLENGER.

the Tropical and Subtropical Atlantic, and was collected by the Challenger at Stations
338 and 346. In 1867 I had observed the same species living, during my stay in the
Canary Island, Lanzerote. A comparison of its form (PI. XXXIX.) with the figures of
the Mediterranean Calpe pentagona exhibits, at first sight, the important differences
between the two species. A third species, different from both, is the inhabitant of the
Tropical Pacific and Indian Ocean, figured by Huxley in his excellent work also as
Abyla pentagona (9, pi. ii. fig. 2). I name it in honour of this naturalist, so highly
respected for his additions to our knowledge of the Acalephs, Calpe huxleyi.

Calpe gegenbauri, n. sp. (Pis. XXXIX., XL.).

Habitat.— Tropical and Southern Atlantic ; Station 338, March 21, 1876; lat. 21° 15'
S., long. 14° 2' W.

Station 346, April 6, 1876 ; lat. 2° 42' S., long. 14° 41' W. Surface.
Canary Islands, Lanzerote, February 1867 (Haeckel).

Nectophores. — The two nectocalyces united are 24 to 28 mm. long ; they are very
different in form and size. The posterior or distal nectophore is 20 to 22 mm. long and
9 to 10 mm. broad; it is twice as broad and four times as long as the anterior or
proximal, whose length is 5 to 6 mm., and the breadth 4 to 5 mm. The ground-form
of the larger is very asymmetrical, that of the smaller quite symmetrical.

Apical Nectophore (figs. 1-4, cs ; fig. 5, apical view; fig. 6, dorsal view; fig. 7,
ventral view ; fig. 8, lateral view from the left side). — The first nectophore (also called
the proximal, anterior, superior or apical nectocalyx) is a pentagonal prism of a com-
pletely bilaterally symmetrical ground-form. When the axis of its nectosac stands
vertically, then the two pentagonal and parallel terminal faces of the prism are also
vertical, and one of their five angles (opposed to the basal side) is directed upwards ; the
two odd apical angles being connected by the horizontal coryphal crest (figs. 5-8, nk).

The pentagonal dorsal face of the first nectophore (fig. 6, ud) covers the nectosac (iv),
and is much smaller than the similar ventral face (fig. 7, iiv), through which the soma-
tocyst (cs) appears, and beyond it the hydrcecium (ui). The two superior lateral angles
of each pentagonal terminal face are much more distant than the two inferior ; and the
lines connecting the two angles at each side (the inferior lateral edges of each pentagon)
are turned inwards, and form an obtuse angle.

The five lateral faces of the pentagonal prism, which separate its two parallel terminal
faces (dorsal and ventral) are two pairs of lateral faces (superior and inferior), and an odd
inferior or basal face (with the openings of the dorsal nectosac and the ventral hydrcecium).

The two paired sujiero-lateral faces of the first nectophore are quadrangular, nearly
rectangular, and connected in the sagittal axis of the body by the coryphal crest (nk) ;

REPORT ON THE SIPHONOPHOR^E. 165

the latter separating them like the ridge of a house-roof. The middle of the coryphal
edge is nearly in contact with the oleocyst (co).

The two infero-lateral faces of the first nectophore are much larger, and of a more
complicated form, sexangular ; the ventral half of their larger quadrangular upper part
being prolonged into an obliquely quadrangular descending plate of half its size (fig. 8) ;
this plate forms the lateral wall of the hydroecium (ui). The inferior dorsal angle of
this plate (between the openings of the hydroecium and the nectosac) is the lowermost
point of the first nectophore ; it marks the basal pole of its principal axis, whilst the
apical pole of the latter is formed by the opposite oleocyst (co), and the centre of the
coryphal edge (nk).

The inferior or the proper basal face of the first nectophore (opposed to the coryphal
crest, nk, fig. 8) is divided by a prominent frontal septum (nt) into two divergent
obliquely ascending secondary faces ; the dorsal or posterior of these is quadrangular and
contains the opening of the nectosac (fig. G, uo) ; the ventral or anterior is pentagonal
and contains the mouth of the hydroecium (fig. 7, inferior third). The basal edge of
the frontal septum is emarginate.

First Nectosac (figs. 5-8, w). — The subumbrella of the apical or proximal nectocalyx
occupies its dorsal half, and is separated by the frontal septum from the ventral parts,
the somatocyst (cs) in the upper, and the hydroecium (ui) in the lower half. The
nectosac is subcylindrical, four times as long as broad ; its closed upper end is near the
dorsal end of the coryphal crest (nk) ; the ostium of its lower end (uo) is surrounded by
a small velum, and opens in the dorsal half of the basal face.

Canals of the Nectosac (figs. 5-8). — A nectocalycine duct (en) arises from the apex
trunci or the top of the hydroecium, and ascends obliquely to the dorsal face of the
nectosac (fig. 8, w). It divides here into four radial canals ; the shortest is the
descending ventral canal of the nectosac, the longest the opposite dorsal canal (fig. 6, cd),
both placed in the median place of the nectophore ; intermediate in size are the two
paired lateral canals (right ex, and left cl) ; these form a small arch in their upper part.
A far larger arch is formed by the dorsal canal, which ascends to the top of the nectosac
and descends alone its whole dorsal median line.

Hydroecium (fig. 7, ui, ventral view ; fig. 8, ui, lateral view from the left side). — The
hydrcecial or funnel cavity is campanulate and occupies the basal half of the ventral
part of the first nectophore. Its rounded apex is closed and from it arise the two
small canals running to the nectophore and the somatocyst. The larger dorsal wall of
the hydroecium is formed by the frontal septum (nt), which separates it from the neigh-
bouring nectosac. The smaller ventral wall is deeply emarginate (fig. 7). The inferior
opening of the hydroecium is quadrangular, obliquely truncated, with four prominent
points or teeth. The two dorsal teeth are the inferior corners of the frontal septum, and
much stronger than the two ventral teeth.

166 THE VOYAGE OF H.M.S. CHALLENGER.

Somatocyst (figs. 5-8, cs). — The somatocyst is spherical, very large, and occupies the
apical half of the ventral part of the first nectophore. It is filled with large vacuolate
entoderm cells and therefore appears reticulate. It is connected at its dorsal side by a
small inferior descending canal with the top of the stem (aa), and by a small superior
ascending canal with the oleocyst (co). The somatocyst is twice as broad and half as
long as the nectosac (w). The oleocyst (co) is a small csecal process filled by an oil-
globule, and is nearly in contact with the middle of the coryphal crest (nk).

Basal Nectophore (fig. 1, ventral view ; fig. 2, dorsal view; fig. 3, lateral view from
the right hand ; fig. 4, from the left hand side). — The second nectophore (also called the
distal, posterior, inferior or basal nectocalyx), is four times as long and twice as broad as
the first, and of a very different form. It is in general a slender, pentagonal, truncate
pyramid, the five edges of which are asymmetrically developed and somewhat spirally
twisted. The ground-form is internally (with respect to the four radial vessels of the
nectosac) quadriradial ; externally (with respect to the five edges of the exumbrella)
quinqueradial ; and at the same time bilateral, with respect to the sagittal plane, which
divides the body into right and left halves, and is determined by the ventral position
of the hydrcecial canal, and the dorsal position of the nectosac (w).

The five edges of the truncate pyramid are more or less wing-like, prominent, and
finish at the distal end in five triangular pyramidal teeth ; they are elegantly denticulate
in the lower third, and twisted in a deltoidal (or right-hand ascending) spiral. Their
development is unequal and asymmetrical. The odd dorsal edge (nd), which runs along
the dorsal median line of the nectosac, is less prominent than the four others, which are
paired. The broadest wing, and the strongest terminal tooth, are developed from the
left ventral edge (n3), and next to this from the right dorso-lateral edge (ft2) ; whilst
the right ventral edge (ft4), and the left dorso-lateral edge (ft1) are smaller.

The two dorso-lateral edges (ft1, ft2) correspond to the two symmetrical lateral
edges of a bilateral and quadriradial Medusa, whilst the two ventro-lateral edges are
produced by the development of the hydrcecial canal on the ventral side of the second
nectophore. This canal is not closed, but covered by the two broad wings which develop
from the two ventro-lateral edges ; the right of these (nx) is broader and overlaps the
left (nl) ; their inferior free margin is dentate.

The truncate apical or proximal face of the second nectophore is obliquely bevelled,
and bears a triangular apophysis, which enters into the hyclrcecium of the first necto-
phore, and encloses the nectocalycine duct. The five edges are more equally developed
at this superior end (fig. 10) ; a horizontal transverse section beyond it (fig. 11)
demonstrates how the two ventro-lateral wings develop more strongly, and form
the hydrcecial canal (ui). The differentiation of the five wings is strongest at the distal
or inferior end.

The basal or distal face of the second nectophore (seen from below in fig. 12) exhibits

REPORT ON THE SIPHONOPHORiE. 167

the opening of the nectosac (uo) surrounded by the velum (v), and at its ventral side
the opening of the hydrcecia! canal (ui). Near the velum arise two small lateral spines,
which lie in the radius of the two much larger triangular teeth, being the distal pro-
longations of the two dorso-lateral edges (nl left, iv right).

Nectosac (figs. 1-4, id1). — The subumbrella of the second nectophore is cylindrical
and occupies its dorsal half. The nectocalycine duct, which comes from the top of the
stem and enters into the subumbrella somewhat below its apex, divides into the four
radial canals (cd dorsal, cv ventral, ex right, cl left). These descend vertically and
nearly parallel to the ostium, where they are united by the circular canal.

Ili/drcccial Canal — The ventral groove of the second nectophore, which forms the
continuation of the hydrcecium of the first, has an irregular form (figs. 10-12, ui, in
transverse section). It is enclosed between the ventral wall of the second nectophore,
and the two broad ventro-lateral wings which arise from it, the right (ux) overlapping
somewhat the left (id).

Siphosome (as). — The long stem, which may be retracted completely into the
hydrcecial canal, bears a series of twenty to thirty or more cormidia. These are
detached from the stem before they reach sexual maturity and swim freely about as
Aglaisma gegenbauri (PI. XL.). They are characterised by a cuboidal bract, which has
a caudal prolongation at the inferior dorsal edge, and by four radial canals arising from
the phyllocyst (two slender odd sagittal and two paired broad lateral). Compare on then-
structure, above p. 119.

Family VIII. Desmoph yid m, Haeckel, 1888.
Desmoph tjidx, HkL, Sj^stem der Siphonophoren, 95, p. 36.

Definition. — Calyconectse polygastriese, with a biserial nectosome, composed of four
to six or more opposite nectophores. Cormidia ordinate, eudoxiform or ersgeiform,
separated by equal free internodes ; each siphon with a bract.

The family DesmophyidaB, represented by two new genera only, is of special interest
as a connecting link between the preceding (VII.) and the following family (IX.). It
agrees in general structure and composition with the Diphyidfe, but differs from them in
the oreater number of nectophores which are arranged in a biserial nectosome. This
latter character is also found in the Polyphyidae, which, however, differ in the absence
of bracts. The Desmoph yidaj may be derived immediately from the Diphyidse, by
multiplication of the nectophores. The Polyphyidee may have arisen from the former
by reduction and loss of the bracts.

Two genera only of Desniophyidee have been observed by me, each with a single
species. Both agree in the form of the rounded edgeless nectophores and bracts with the

168 THE VOYAGE OF H.M.S. CHALLENGED

Prayidae, and are probably derived from this subfamily of Diphyidse. The two genera of
the former correspond to those of the latter.

Desmalia, the first genus, is in general appearance very similar to Pray a (Pis.
XXXI. ,t XXXIL), and possesses, like it, eudoxiform cormidia. Each eudoxome is
composed of two medusomes, a sterile and a fertile. The sterile medusome exhibited in
the only species observed nearly the same shape as that of Praya galea, figured in
PI. XXXII. The cavity of the helmet-shaped bract contained a single siphon with a
tentacle, and on the ventral side of the former a single gonophore with a well-developed
umbrella. All gonophores of the single specimen observed were female. The corm of
Desmalia may be, therefore, dioecious.

Dcsmophyes, the second genus, is described in the sequel (PL XXX.). It is in
general composition and special structure very similar to Lilyopsis, and possesses, like
this Prayid, ersseiform cormidia. Each ersaeome is composed of two sterile and one or
several fertile medusomes. The first sterile medusome consists of a bract (an umbrella
with four radial canals), a manubrium (siphon), and a tentacle. The second sterile
medusome is represented by a well-developed " special nectophore," a medusiform
umbrella with four radial canals and a ring canal, muscular subumbrella and velum, but
without manubrium. The umbrellar margin of this Medusa was beset (in the only
species observed) with a corona of rudimentary tentacles and ocelli (almost as in some
species of Lilyopsis). The group of sexual medusomes was represented by several
clustered fertile gonophores ; one large, and a number of small vicarious buds. The
corm was monoecious and diclinic, the cormidia alternately males and females.

The development of the Desmophyidse is not known ; but it will probably be found
to be hypogenesis, the gonophores ripening whilst sessile on the stem ; as is also the case
in the closely allied Polyphyidaa.

Synopsis of the Genera of Desmophyidie.

Cormidia eudoxiform, composed of two medusomes (one sterile and one fertile), without

special nectophore, ......... 32a. Desmalia.

Cormidia ersseiform, composed of three or more medusomes, with a special nectophore, . 32b. Desmophyes.

Genus 32a. Desmalia,1 n. gen.

Definition. — Desmophyidaj with rounded edgeless nectophores, arranged in a biserial
nectosome. Cormidia without special nectophores.

The genus Desmalia is represented by a polygastric Calyconect, which is in general
very similar to the common forms of the well-known genus Praya, but differs from

1 / hsmalia — Marine chain, ota/xt?, cihuf.

REPORT ON THE SIPHONOPHORjE. 169

them in the possession of numerous (four to six or more) nectophores, arranged in a
biserial nectosome similar to that of Hippopodius and Polyphyes.

A single specimen only of this genus was captured by me during my voyage through
the Indian Ocean, between the Maldive Islands and Socotra, in March 1882. But
unfortunately it was injured during capture, and decomposed before I could make a
sketch of it. The general appearance and the form of nectophores and bracts were
similar to the figure which Fewkes published in 1880 as "the young of Pray a
cymbiformis." * But instead of two opposite nectophores there were four present, the
superior pair somewhat smaller than the inferior. The cormidia, fifteen to twenty or
more, succeeded on the stem of the siphosome nearly without intervals, so that the
helmet-shaped bracts covering one another formed a continuous series of scales, whence
I called this species provisionally Desmalia imbricata. A fragment of a similar
siphosome was found in a bottle from the Challenger collection, taken in the South
Pacific (Station 165). The structure of the cormidia, and mainly the form of the helmet-
shaped bract (with four radial canals), was similar to that of Praya galea (PI. XXXIL).
Each eudoxiform cormidium contained on the ventral side of the siphon a single
gonophore with well-developed umbrella and a small ovarium. All the cormidia were
female.

Genus 32b. Desmophyes,2 Haeckel, 1888.

Desmophyes, Hkl., System der Siphonopkoren, p. 36.

Definition. — Desmophyidse with rounded edgeless nectophores, arranged in a biserial
nectosome. Each cormidium provided with a small special neetophore.

The genus Desmophyes is closely related to the preceding Desmalia, but differs from
it in 'the possession of a special neetophore on each cormidium, and by the reduction of
the umbrella of the gonophores. It agrees in these characters with Lilyopsis, and has
the same relation to this Diphyid genus as Desmalia bears to Praya.

The only species of Desmophyes which I observed, and which is described in the
sequel, agrees with some species of Lilyopsis, not only in the general composition of
the cormidia, but also in the special form of their component parts. The special
neetophore of each cormidium bears on the margin of the medusiform umbrella a number
of ocelli and a corona of rudimentary tentacles (almost as in Lilyopsis medusa, &c.).
Whilst the subumbrella is strongly developed in these special nectophores, it is
reduced in the gonophores, which possess a long prominent manubrium. Each
cormidium has a number of buds besides the mature gonophore.

1 Bull. Mus. Comp. Zool., vol. vi. No. 7, p. 146, pi. iii. fig. 2.

2 Desmophyes = Chain-lLke animal, oioftos, (pins.

(zool. chall. exp.— part lxxvii. — 1888.) Hhhh 22

170 THE VOYAGE OF H.M.S. CHALLENGER.

Desmopliyes annectens, n. sp. (PI. XXX.).

Habitat. — Indian Ocean, south coast of Ceylon, December 1881 (Haeckel).

Nectosome (fig. 1). — The swimming column was composed, in the only specimen
observed, of six nectophores arranged in two opposite series. The two uppermost
nectophores were half as large as the two lowermost, and the two bells of the second pair
placed between them, intermediate in size. Each of the two largest inferior nectophores
had a length of 15 mm. and a breadth of 10 mm., and the entire biserial nectosome was
about 30 mm. long; and 18 mm. broad.

Nectophores. — The swimming-bells are on the whole very similar to those of Praya
galea, their jelly soft and delicate, the surface smooth and rounded, without edges. The
form is obliquely campanulate or mitriform, the apical part rounded, the basal part with
the ostium obliquely truncate.

The dorsal (outer or abaxial) face of each nectophore is convex and smoothly rounded,
as is also the lateral face. The ventral face, however (turned to the common axis of
the stem), is concave and forms two parallel, longitudinal, prominent wings, which
embrace a hemicylindrical groove. The ventral grooves of each two opposite nectophores
are so fitted one into another that they form together a cylindrical canal. This axial
tube, tapering towards the apex, is the hydrcecial canal, which encloses the superior part
of the common stem ; the contracted siphosome may be partly retracted into it.

Each nectophore is attached to the common stem by means of a short pedicle, a
vertical triangular lamella, which arises by a broad base from the upper third of the
ventral groove, and is fixed at its apex to the uppermost part of the stem. The pedicle
encloses the peduncular canal which connects the stem-cavity with the nectosac.

Nectosac. — The inferior basal or distal half of each nectophore is occupied by the
muscular subumbrella, which has an obliquely campanulate form. Its basal mouth is
wide, and surrounded by a broad velum. The four radial canals of the suburnbrclla are
of different lengths, the two lateral canals (right and left) being larger than the ventral
(or axial) canal, and smaller than the dorsal (or abaxial) canal. They unite at the base of
the velum by a circular marginal canal, and this is beset with eight red pigment spots
or ocelli, similar to those in the special nectophores of the cormidia. Four of them are
placed perradially (at the distal end of the four radial canals) and four others inter-
radially (between the former). There are no rudimentary teutacles on the margin of
the umbrella ; these are peculiar to the special nectophores.

The superior, apical or proximal, half of the nectophore contains two canals which are
placed in its sagittal plane. The peduncular canal, which arises from the canal of the
common stem in its uppermost part, enters by the triangular pedicle of the nectophore in
its jelly-substance, and descends obliquely in a curve towards the apex of the subumbrella,

REPORT ON THE SIPHONOPHOR^. 171

where it divides into the four radial canals. From the proximal base of this pedicular
canal arises a blind pallial canal, which ascends towards the dorsal median line of the
exumbrella, and ends near its apical part by a small csecal diverticulum (just as in
Lilyopsis). There is no inferior or descending pallial canal, as in Praya.

Siphosome. — The long tubular stem of the cormus, which proceeds from the basal
opening of the hyclrcecial canal (between the two lowermost nectophores), is beset in its
upper part with numerous buds of cormidia, and bears in its lower part a series of fully
developed sexual cormidia, separated by equal free internodes ; their number in the
specimen observed was about a dozen. Male and female alternate regularly.

Cormidia. — Each cormidium is essentially composed as in Erssea, of at least three
different medusomes ; firstly, a sterile medusome composed of a bract, a siphon, and a
tentacle ; secondly, a special nectophore ; and thirdly, a male or female gonophore ; the
latter bears a number of similar buds or reserve gonophores at its base. The entire
composition of the cormidia is very similar to those of Lilyopsis. The subumbrellar
cavity of the bract covers the greater part of the other organs ; these are placed as
usual, so that the siphon and its tentacle occupy the dorsal part of the cavity, the
special nectophore the ventral part, and the gonophores lie between them on both
sides.

Bracts (fig. 2b, from the right side ; fig. 36, from the left side). — -The covering scales
of the cormidia, bracts or hydrophyllia, are very similar to those of Praya. They have
the form of a flat cap or an overturned boat, and are about 10 mm. long by 5 mm. broad.
Their ground-form is bilateral, more or less asymmetrical, their surface smooth, with
rounded edges. The upper convex face is compressed from both lateral sides ; the lower
face contains a deep irregular subumbrellar cavity, in which the organs of the cormidium
are partly hidden. The jelly-substance of the umbrella is much thicker in the ventral
than in the dorsal part of the bract ; it is thinnest on both lateral sides, which are deeply
cleft in the middle.

Through the base of this deep lateral fissure passes the common stem of the siphosome
(a). The axial canal of this latter gives off a short branch to each bract, which forms
near the point of its attachment a small pyriform diverticulum (be). From the base of
this phyllocyst arise four radial canals, which enter into the jelly-mass of the bract, are
irregularly bent, and end in a vesicular diverticulum. Two of these four canals are
odd, and lie in the oblicme sagittal plane of the bract, a shorter ventral (cv ) and a longer
dorsal (cd) ; the two others are paired lateral canals, and enter into the dorsal lobes of
the bract (right ex, and left el).

Siphons (figs. 2, 3, s). — The single polypite, which occupies the dorsal part of each
bract-cavity, has the usual form of siphons in Calyconectae. A thick-walled ovate
basigaster (sb) is connected by a short pedicle with the common stem (a). The large
ovate or pyriform stomach exhibits in its wall eight distinct orange-coloured liver-stripes

172 THE VOYAGE OF H.M.S. CHALLENGER.

(sh). The contractile and very mobile proboscis (sr) terminates in a suctorial mouth,
the margin of which sometimes is regularly octolobate (fig. 3, ss).

Tentacles (figs. 1, 2, 3, t, 8). — The single tentacle which arises from the pedicle of each
siphon in the most dorsal part of the bract-cavity is of the form usual in Calyconectse.
It is very long and contractile, and beset with very numerous equidistant tentilla.
Each of the latter (fig. 8) bears on its pedicle an elongated reniform cnidosac (tk), and this
contains on each side of the cnidoband (km) a group of six to eight large ensiform
cnidocysts (kl). The pedicle (tt) as well as the terminal filament (tf) is inflated and
vesicular at the distal end.

Special Nectophores (figs. 2, nn, 6). — The special nectophore of each cormidium,
which is placed in the ventral part of the bract-cavity, offers in Desmophyes a most
interesting medusiform structure, similar to that of Lilyopsis. The umbrella is bilaterally
symmetrical, since its jelly-mass is more developed in the dorsal than in the ventral
part ; it arises by a conical pedicle, which fits into the apex of the bract-cavity. The
pedicular canal, which arises from the common stem, does not enter into the apex of
that pedicle, but into the middle of its dorsal edge (fig. 6, cp).

The subumbrella of the special nectophore (to) is hemispherical, occupies its basal
half and opens by a wide mouth, surrounded by a broad velum (v). The four radial
canals (cr), which arise from its apex, are united at its margin by a circular canal (cc).
The margin of the umbrella, beyond the latter, is beset with eight red pigment spots or
ocelli (uy), four of these lie perradially (at the distal end of the radial canals), four others
in the middle between them. They are relatively larger than in the main nectophores.
Besides, the margin of the umbrella is beset with a corona of sixteen short tentacles (t) ;
eight placed beyond the ocelli, and eight others alternating with these, between the former.

Gonophores (figs. 2, f, 4, 5). — Desmopjhyes is monoecious and diclinic, both sexes
alternating so regularly that each cormidium has gonophores of one sex only, and two
neighbouring gonophores always being of different sexes, forming together a pair.
Each cormidium bears only one fully-developed gonophore ; but at its base are placed
the buds of several reserve gonophores. They lie between the dorsal siphon and the
ventral special nectophore.

Androphores (fig. 4). — The male gonophores exhibit, fully developed, a very large,
spindle-shaped manubrium (Am), with a cylindrical central spadix (hx); it is widely pro-
minent from the cavity of the small retracted umbrella (u) ; the latter envelopes only the base
of the former, but exhibits four distinct radial canals (cr) and a uniting circular canal (cc).

Gynop>hores (figs. 2,f, 5). — The female gonophores have a campanulate umbrella (f)
larger than that of the males, also with four well-developed radial canals (cr) and a
connecting circular (cc). The cavity of the subumbrella in ripe females is filled by a
large pyriforrn or subglobular manubrium, which contains usually four large ovules of
equal size, disposed in form of a cross (o).

REPORT OX THE SIPHONOPIIORiE. 173

Family IX. Polyphyid m, Chun, 1882.

Pohjphyidx, Chun, 86, p. 12.
Hippopodidse, Kolliker, 4, p. 28.

Definition.— Calyconectee polygastricae, with a biserial nectosome, composed of four
to six or more opposite nectophores. Cormiclia ordinate, separated by equal free inter-
nodes, always without bracts.

The family Polyphyidae differs from the other polygastric Calyconectae in the
complete absence of bracts. The nectophores are numerous, and arranged in a biserial
nectosome, as in the preceding Desmophyidaj, from which they may be derived by the
reduction of the bracts. The general composition of the cormidia, as well as the special
structure of the single parts composing them, is very similar to that of the other Caly-
conectae (mainly Prayidae) ; but in some respects they approach more to the Physonectse.

The oldest and best known form of Polyphyidae is the common Mediterranean
Hippopodius gleba, described and figured so early as 1775, by Forskal, under the name
Gleba hippopus (11, pi. xliii. fig. e). It has been mentioned under very different names
by later authors (compare 33, p. 22). The first accurate anatomical description of it was
given in 1853 by Kolliker (4), others by Vogt (6) and Leuckart (8). Kolliker observed
a second Mediterranean form of this family, which he called Vogtia pentacantha (4,
p. 31, Tab. viii.) ; and he established for these two genera the family Hippopodidae,
differing from the Physophoridse in the absence of a pneumatophore, from the Diphyidae
in the possession of numerous nectophores arranged in a biserial nectosome similar to
that of the Agalmidae. Chun afterwards (1882) called the same family Polyphyidae (in
opposition to Diphyidae and Monopkyidae). Leuckart united the Hippopodidae and
Diphyidae in his group Calycophoridae (8).

Nectosome. — The nectophores of the Polyphyidae are always numerous, at least four
to six, often eight to twelve, sometimes more. They are constantly opposed in alternate
pairs and arranged in a biserial column, similar to that of the Agalmidae. But a remark-
able difference exists in the form and the structure of the trunk. The tubular trunk or
common stem of the nectosome, which bears the nectophores, is, in the Agalmidae,
Apoleniidse, and other Physonectae, the rectilinear prolongation of the trunk of the
siphosome, which bears the siphons and gonophores ; the former is the superior and the
latter the inferior part of a straight, cylindrical tube. Quite different is the relation of
the two parts of the trunk in the Hippopodidae, as was first pointed out by Leuckart.1
The superior part of the common stem, or the trunk of the nectosome, is connected with
the inferior part, or the trunk of the siphosome, at a small acute angle, which forms
the top of the corm. Both descend together from the top, and the deflexed trunk
of the nectosome, bent down upon itself, forms a spiral band which surrounds the

1 8, p. 303, Taf. xii. fig. 3 ; 35, p. 553, Taf. xlvii. fig. 27.

174 THE VOYAGE OF H.M.S. CHALLENGER.

trunk of the siphosome in wide spiral turnings. Hence, it appears as though the axis
of the cone formed by the nectophores was only a lateral branch of the upper end of the
ccenosarc ; but in reality the upper part of the latter is deflexed and turned ai'ound the
lower part. The youngest and smallest nectophores, therefore, are placed at the upper-
most part, the oldest and largest at the lowermost part of the nectosome. The point
of vegetation of the former is very near to that of the siphosome, but separated from it .
by a small interval (PI. XXIX. fig. 7, x. Compare 35, p. 553, Taf. xlvii. fig. 27, ah).

Nectophores. — The nectocalyces of the Polyphyidse appear in two different forms,
which are characteristic of the two subfamilies of this family. The Hippopodidae (sensu
stricto) have smooth nectophores, similar to a horse-shoe, with rounded surface (Hippo-
poclius and Polyphyes, PL XXIX. figs. 1-8); they may be derived from the Prayidse. The
Vogtidae, on the other hand, represented by the genus Vogtia (figs. 9-14), have pentagonal
nectophores with angular surfaces ; they may be derived from the Diphyopsidse. The
fundamental form is always bilaterally symmetrical, a deep ventral groove dividing the
nectophore into two equal halves. The jelly-substance is veiy voluminous and usually
hard, cartilaginous ; the nectosac is relatively very small and more or less rudimentary.

The special form and the arrangement of the nectophores in alternately opposite
pairs are very peculiar. That part of the nectophore which bears the circular opening of
the nectosac must be regarded, of course, as the basal part. Opposite to this is the apical
part, or the true pedicle of the nectophore, a small triangular lamella, by which it is
attached to the common stem. This pedicle arises in the sagittal plane of the nectophore,
midway between the two parallel ventral wings, which include the deep concave ventral
groove. Strictly speaking, only the vertical inferior half of this axial groove, beyond the
pedicle, represents the ventral side, whilst its superior half, above the pedicle, belongs to
the dorsal side. The outer or abaxial part of this latter forms the free convex dorsal
face of the nectophore, which ascends more or less vertically in the lateral profile view of
the nectosome. Each nectophore embraces with the two lateral wings of the ventral
groove the adjacent parts of two other (superior) nectophores ; with the descending-
ventral part of the wing the same part of the opposite nectophore, and with the
ascending dorsal part of the wing the basal part of the superjacent nectophore of the
same side. An important consequence of this peculiar arrangement is, that the openings
of the nectosacs become hidden and nearly closed by the uppermost covering part of the
subjacent nectophore ; only the openings of the two lowermost (oldest and largest)
nectophores lie quite open, and are not covered.

Nectosac. — The swimming cavity in the nectophores of the Polyphyidse is very small,
flat, and reduced, and the muscle-plate of its subumbrella very thin ; the power of
swimming therefore very weak. Indeed these Calyconectae swim more slowly than any
of the other groups of this order. The velum, too, which surrounds the wide opening of
the nectosac, is very small, usually crescentic or sickle-shaped, broader in the dorsal

REPORT ON THE SIPHONOPHOR^. 175

(superior or abaxial) half than in the rudimentary ventral (inferior or axial) half. The
wide opening or ostium of the flat nectosac is sometimes circular, at other times reniform
or even cordate, notched by a deep incision in the middle of the ventral margin. Usually
two strong ventral teeth (or the lowermost apophyses of the two lateral wings) are
prominent over both sides of that notch.

Canals -of the Nectosac. — The subumbrella of the nectophores possesses in the
Polyphyidse, as in all other Siphonophorse, four radial canals, united by a marginal ring-
canal above the velum. But they are here peculiarly differentiated. The pedicular
canal of each nectophore, which arises from the tubular stem and runs through the
lamellar pedicle, is short and divides in the middle of the ventral groove into two
branches, an ascending and a descending. The ascending branch is a simple blind
pallial vessel (corresponding to the superior mantle-canal of Pray a) ; it runs in a radial
direction, inside the jelly-mass of the nectophore, towards its outermost and uppermost
dorsal angle (between the median line of the ventral groove and the dorsal side of the
nectosac). The descending branch runs to the top of the subumbrellar cavity, and
divides here into four very unequal branches or radial canals. The median dorsal and the
two paired lateral canals are very short, and soon open into the marginal canal. The
median ventral canal, however, is very long and dilated towards the margin of the
umbrella ; it forms here a flat sinus or diverticulum, the form of which is very
characteristic of the individual species (sinus ventralis, cv", figs. 3. 4, 13, 14). It is
elliptical or ovate in Hippopodius gleba, hexagonal in Polyphyes ungulata, two-winged
in Vogtia kbllikeri, &c. The cells of the entoderm, which line the flat and broad cavity
of this ventral sinus, are very large, polygonal, and filled with peculiar fine granules.
The narrow intervals between the single cells have been described by Claus as " peculiar
ramifications of the vessel" (35, p. 553).

Siphosome (fig. 1). — In the Polyphyidae the trunk of the siphosome, or the common
stem which bears the cormidia, is usually contracted and retracted into the hydrcecial
cavity of the nectosome. But in the expanded state, and protruded through the basal
opening of that cavity, it is a rather long tubular stem, two, three, or more times as long
as the nectosome. The number of cormidia is sometimes small, four to eight, at other
times much larger, twenty to thirty or more ; besides the numerous buds of young
cormidia, which are found in a crowded ventral series along the uppermost part of the
siphosome (PL XXIX. fig. 7, is).

Cormidia. — The groups of polymorphous persons, which cover the trunk of the
siphosome, differ from those of all other polygastric Calyconectse in the complete absence
of bracts. This may be explained either by total reduction and loss of the hydrophyllia
(perhaps in correlation with the development of the large nectosome and its peculiar
hydrcecial cavity), or by a phylogenetic dislocation of organs which were originally
connected. It is possible, that in older ancestral forms of this family, the

176 THE VOYAGE OF H.M.S. CHALLENGER.

umbrellas of the sterile medusomes were separated from the appertaining siphons, and
both so dislocated, that the former migrated upwards and together composed the
nectosome ; whilst the manubria with the tentacles remained in the cormidia, composed
of clustered sexual medusomes or gonophores.

The cormidia of the Polyphyidse are ordinate and monogastric, as in all other
Calyconectse, separated by free internodes of the stem, of equal length. Each cormidium
contains a single siphon and one tentacle, besides a group of clustered gonophores.
These are sometimes of one sex in each cormidium, so that this is diclinic. The corm
itself is monoecious, male and female cormidia occurring on the same stem ; usually the
androphores occupy the lower or distal part, the gynophores the upper or proximal part
of the siphosome. At other times the cormidia are monoclinic (composed of gonophores
of both sexes) as described by some authors (Kolliker, 4, and Weismaim, 1883, p. 194).

The general rule, that the cormidia are ordinate in all polygastric CalyconectaB, has
perhaps a single exception in Polyphyes. The clustered gonophores are here separated
from the base of the siphon by a small interval, and this seems to become larger in some
species, so that the cormidia may be described as alternate (or even irregular), the sterile
medusomes (siphon and tentacle) alternating with the fertile (gonophores), just as in
man}' Physonectse (Agalma, Agalmopsis, &c). This is perhaps the case in the
Mediterranean form described by Kolliker as Hippopodius neapolitanus (4, Tab. vi.), and
in a similar South Atlantic form, an incomplete specimen of which I observed in a bottle
from the Challenger collection (from Station 325), and which I have called provisionally
Polyphyes dissolutus (95, p. 36). The preservation of this fragment, however, was not
sufficiently good to furnish confirmation of that statement, and since the description of
Kolliker has not been confirmed by later authors, it may be that an accidental error
occurred, and that the cormidia are always ordinate as in the common Hippopodius.

Siphons (fig. 1, s). — The polypites of the Polyphyidse are in general of the same shape
as in the other Calyconectse. The pedicle arising from the siphosome is sometimes longer,
at other times shorter or even rudimentary. The basigaster is subspherical or ellipsoidal,
its thickened exoderm full of cnidocysts. It is separated by a pyloric valve from the
ellipsoidal or spindle-shaped glandular stomach, which passes over without a sharp
boundary line into the long and very contractile proboscis. Sometimes these parts are
very prolonged and vermiform. The distal mouth is small and simple, but may be
expanded in the form of a circular suctorial disc.

Tentacles (fig. 1, t). — The single tentacle, which is attached to the base of each siphon,
is very long and thin, beset with a series of very numerous tentilla. Each tentillum
(fig. 8) is composed of a long pedicle, a roundish cnidosac, and a cylindrical terminal
filament ; the latter is often coiled up spirally. The cnidosac is relatively small, ovate,
ellipsoidal or subspherical, often coloured by yellow or orange pigment. Its cnido-battery
is placed in form of a curved band along the convex dorsal side of the cnidosac, and

EEPOET ON THE SIPHONOPHOR^E.

177

composed of innumerable small paliform cnidocysts ; on each side of it lies a bunch of a
few large ensiform cnidocysts (usually four to eight, rarely more).

Gonophores. — The sexual medusomes of all Polyphyidae come to maturity whilst
sessile on the stem. There is, therefore, in this family no true metagenesis, as in the
Diphyidse and Monophyidte. The cormidia are sometimes diclinic {Hippop>odius), at
other times monoclinic (Polyphyes and Vogtia). Usually the gonodendra are small, and
only one or two large mature gonophores exist between a small number of immature
and young buds. Usually in the diclinic corms the female gonophores occupy the
superior, the male gonophores the inferior part of the siphosome. The gonophores of
both sexes have a well-developed, hemispherical or campanulate umbrella, with four
radial canals and a connecting ring-canal above the small velum. The manubrium, from
the exoderm of which the sexual cells are developed, is ovate, spindle-shaped or cylin-
drical ; it becomes very large and widely protruded through the ostium of the
subumbrella, often two to four times as long as the latter, or even more. Thus the
form of the gonophores in the Polyphyidae is more like that in the Physoneetae than
in the other Calyconectse.

Synopsis of the Genera of Polypliyidie.

I. Subfamily Hippopodioe. ] Ostium without teeth, cormidia diclinic, .
Nectophores rounded, not >

prismatic. ) Ostium with six teeth, cormidia monoclinic,

II. Subfamily Vogtid.e.

Nectophores five-sided, pris- J- Ostium with five teeth, cormidia monoclinic,
niatic.

33. Hippopodius.

34. Polyphyes.

35. Vogtia.

Subfamily Hippopodid^e.

Genus 33. Hippopodius,1 Quoy and Gaimard, 1827.
Hippopodius, Quoy and Gaimard, Ann. d. Sci. Nat. (ZooL), t. x.

Definition. — Polyphyidae with rounded horseshoe-shaped nectophores, the ostium of
which is smooth or sbghtly lobate. (Cormidia diclinic. Gonophores attached to the
base of the siphons. )

The genus Hippopodius is the most common of the three genera of Polyphyidae, and
is represented by the well-known Mediterranean type Hippopodius gleba, and by several
similar species, which are widely distributed over all warmer seas. I found single
detached nectophores of it in different bottles in the Challenger collection, taken in the
Tropical Pacific and Atlantic ; and also in the collection of Captain Rabbe, from the Indian

1 Hippoj)odius = Horse-shoe, iVxof, woS/o

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.)

Hhhh 23

178 THE VOYAGE OF H.M.S. CHALLENGER.

Ocean. They differ in size and form, and especially in the shape of the basal face and the
ventral sinus, more or less from the Mediterranean species, but were not sufficient for
the definition of distinct species. To enable this, a further accurate examination and
comparison of the entire corm, from different localities, is required.

The most accurate description of the Mediterranean Hippopodius gleba ^Hippo-
podius luteus, Vogt, 6, very common on the Riviera) is given by Leuckart.1 It differs
somewhat from similar forms taken in other parts of the Mediterranean. That form
which Kolliker has described as Hippopodius neapolitanus from Messina ( = Elephantopus
neapolitanus, Lesson, 3) seems to belong to the following genus, Polyphyes. The mouth
of the nectosac is surrounded in the latter by six prominent teeth (four dorsal and two
ventral), whilst it is smooth and toothless in Hippopodius. Another important difference
between these two genera seems to be found in the composition of the cormidia. The
clustered gonophores are diclinic, and attached to the base of the siphon in Hippopodius,
whilst they are monoclinic and separated from it by a small interval in Polyphyes.
Both genera together make up the subfamily Hippopodidae.

The striking contradictions between various authors, respecting the sexual organs of
Hippopodius, can be explained only by the assumption that these two similar genera
have been confounded. The description which Leuckart has given of the diclinic
cormidia of Hippopodius gleba (8) is as correct as that which Kolliker has given of the
monoclinic cormidia of Hippopodius neapolitanus (4). The accuracy of these latter
observations has been confirmed recently also by Weismann, in his work on Die
Entstehung der Sexual-Zellen bei den Hydromedusen (1883, p. 194). He found in
each cormidium associated a single female and two male gonophores. Perhaps these
differences in the composition of the cormidia of the two genera are more important
than those in the form of their nectophores.

Germs 34. Polyphyes,2 Haeckel, 1888.
Polyphyes, Hkl., System der Siphonophoren, p. 36.

Definition. — Polyphyidas with rounded horseshoe-shaped nectophores, the ostium of
which is surrounded by six prominent apophyses. (Cormidia monoclinic. Gonophores
separated from the base of the siphons.)

The genus Polyphyes differs from the preceding closely allied Hippopodius as well
in the form of the nectophores as in the composition of the cormidia. The nectophores
have in general the same horseshoe-shape as in Hippopodius ; but in this latter their
dorsal face is equally convex and smooth, and passes over into the lateral faces without
a sharp edge. In Polyphyes their dorsal face is nearly quadrangular, and separated by
two lateral parallel smooth edges from the lateral faces ; further, the basal edge of their

1 8, pp. 299-309, Taf. xii. figs. 1-4. 2 Polyphyes = Animal with numerous buds, ■no^vipvris.

REPORT ON THE SIPHONOFHOR^. 179

dorsal face, or the dorsal circumference of the ostium, is provided with four descending
lobes or triangular teeth, which are wanting or but slightly indicated in Hippopodius.
The two basal apophyses of the lateral ventral wings are also more prominent than in
the latter, and the mouth of the nectosae therefore surrounded by six teeth. The
general form of nectophores in Pohjplnjes, therefore, is intermediate between that of
Hippopodius and of Vogtia. Another difference seems to be indicated by the monoclinic
cormidia and the position of the gonophores, which are attached to the base of the
siphons in the two latter genera, separated from it by an interval in Polyphyes.
(Compare the preceding description of Hippopodius.)

The typical species of this genus, described in the sequel, was observed by me in
1866 in the Canary Islands, and detached nectophores of it found again in the Challenger
collection (Station 352, Tropical Atlantic). The characteristic form, however, of the
nectophores, with the six strongly prominent teeth, figured in PL XXIX., is more
developed in the specimens from Station 352 than in those which I observed
myself in Lanzerote. These latter approach more to the southern Mediterranean form
described by Kolliker as Hippopodius neapolitanus (4).

Polyphyes ungulata, n. sp. (PI. XXIX. figs. 1-8).

Habitat. — Tropical and Subtropical Atlantic; Station 352, April 13, 1876;
lat. 10° 55' N., long, 17° 45' W. Surface.

Canary Islands, Lanzerote; December 1866 and January 1867 (Haeckel).

Nectosome (fig. 1). — The swimming column is composed of five or six pairs of
obliquely opposed nectophores, the size of which increases from the rounded top towards
the bevelled base. The general outline of the compressed nectosome is ovate seen from
the broad side, more lanceolate seen from the narrower side. The connection of the
united nectophores is very firm, each embracing the base of the superjacent nectophore
by the two lateral wings of its ventral groove ; and also the opposite basal apophyses of
the opposite superior nectophore.

Nectophores (figs. 1, 2, lateral view; fig. 3, apical view; fig. 4, basal view; fig. 5,
ventral view; fig. 6, dorsal view). — The largest neetocalyces have a diameter of 15 to
20 mm., and possess the form of an inverted horse's hoof, the lower face of which is turned
upwards. Five faces may be distinguished in the wedge-shaped horse-shoe, which
represents an obliquely bevelled segment of a cone ; an inferior basal face, an exterior
dorsal face, an interior ventral face, and two paired lateral faces. The basal face, directed
obliquely downwards and outwards, contains the reniform or subcircular mouth of the
nectosae (figs. 3, w, 4) and the creseentic velum (v) ; it is surrounded by six prominent
paired teeth, four dorsal and two ventral triangular apophyses ; the two lateral dorsal

180 THE VOYAGE OF H.M.S. CHALLENGER.

teeth are larger than the two median, and smaller than the two descending ventral teeth
(fig. 4, nx, right; nl, left).

Exactly opposite to the basal face of the nectophores is the large axial or ventral
groove directed obliquely upwards and inwards ; it is limited by two prominent wings,
the axial edges of the two paired lateral faces ; these wings diverge towards the inferior
(ventral) and more strongly towards the superior (dorsal) end of the axial groove, while
they approach one another in the middle and at the dorsal corner of the groove (fig. 3).
A small and thin triangular lamella, the pedicle of the nectophore, arises in its sagittal
plane, in the middle of the axial groove, and is attached to the trunk of the nectosome
by its axial apex. Strictly speaking, that part of the axial groove which lies below the
pedicle is the ventral, and the opposite part, above the pedicle, the dorsal portion.

The dorsal or abaxial face of the nectophore (superior half of fig. 4) is a convex,
vertical, nearly quadrangular plate, limited by four edges, and divided by three nearly
parallel ridges into four oblong facettes. Each of these ends below in a triangular
descending tooth ; the two median teeth being smaller than the two lateral. The
opposite superior edge of the dorsal face exhibits an odd median prominence and two
smaller paired lateral (fig. 4, above).

The two paired lateral faces of the nectophore (right and left) are oblongish, convex,
smooth (figs. 1, 2), and prolonged below into the two ventral teeth, which embrace the
common stem of the nectosome. They are separated from the concave axial groove by
the prominent edge of the lateral wing, from the convex dorsal face by the vertical
lateral edge of the latter.

Nectosac (figs. 2-5, iv). — The subumbrellar cavity, which occupies the bevelled basal
face of the nectophore, is very shallow (fig. 2, w, in profile). Its wide ostium is sub-
circular, slightly reniform owing to a small median notch on its ventral side. The
muscle-plate of the subumbrella is very thin and weak. The small velum (v) is sickle-
shaped, rudimentary in the ventral half, broader in the dorsal half.

Canals of the Nectophores (figs. 2-4, c). — The nectocalycine duct passes from the
trunk through the small pedicle of the nectophore directly towards the top of the
subumbrella. Before reaching this, it gives off an odd long pallia! vessel, which ascends
obliquely in the jelly of the umbrella (immediately below the sagittal median line of the
axial groove) and ends blindly near the dorsal aj>ex of the nectophore (figs. 2-4, ce).
The four radial canals, which arise from the top of the subumbrella and are united by
the circular marginal vessel, are of very unequal length. The two paired lateral canals
(right and left) are little longer than the short dorsal canal and ascend- obliquely upwards,
close to the latter. Much longer is the ventral canal (cv), which descends obliquely and
before reaching the marginal canal expands in the form of a hexagonal or square ventral
sinus (cv"). Its form is very characteristic of the species ; it has six prominent corners,
two median in the sagittal axis, two smaller ventral and two larger dorsal on both

REPORT ON THE SIPHONOPHOR^. 181

sides ; it occupies nearly the ventral half of the subumbrella. It is relatively three
or four times as large as the small ovate or lanceolate ventral sinus of the common
Hippopodius gleba. (Compare Leuckart, 8, Taf. xii. figs. 1, 2.)

Siphosome (figs. 1, 7). — The siphosome of Polyphyes ungulata, and its numerous
appendages, are very similar to those of the well-known Mediterranean Hippopodius
yleba, accurately described by Leuckart (8) and others. An important difference,
however, seems to lie in the origin of the clustered gonophores, which are not attached
immediately to the base of the siphons (as in the latter), but separated from them by
a small interval. The cormidia, therefore, strictly speaking, are not perfectly ordinate,
but more or less loose, since the loosely aggregated gonophores alternate with the
single siphons. The number of the cormidia is very great in the largest specimens, up
to twenty or twenty -five ; besides the numerous small buds of developing cormidia,
which are crowded at the top of the siphosome (fig. 7, as). The latter is separated
from the top of the deflexed nectosome (an) by a small interval. The trunk of the
nectosome is coiled spirally around the proximal portion of the trunk of the siphosome.

Siphons (fig. 1, s). — -The polypites are in the expanded state about as long as a
nectophore, and bear on a small pedicle a subspherical basigaster, followed by a long
spindle-shaped stomach ; this passes over into a long and narrow, very contractile
proboscis, which opens by the terminal mouth. The mouth is often expanded in the
form of a circular suctorial disc (fig. 1 , ss).

Tentacles (fig. 1, t). — The capturing filament, attached to the pedicle of each siphon,
is very long and bears a single series of equidistant tentilla. Each tentillum bears on
a long pedicle, which is covered with papillae (fig. 8, tp), a subspherical or ellipsoidal
cnidosac, and attached to its base a long simple terminal filament (spirally coiled up in
fig. 8, tf). The cnidosac contains a long, nearly annular cnido-battery, following its dorsal
convexity, and composed of very numerous, small paliform cnidocysts (fig. 8, km) ; and on
each side of it a paired lateral patch, composed of four very large ensiform cnidocysts
(fig. 8, M).

Gonophores. — Attached to the trunk, near the pedicle of the siphon, but separated
from it by a small interval, are the monoclinic gonophores. Each cormidium bears in
the superior part usually a single large female, in the inferior one or two male, gonophores,
besides a small number of buds or younger forms. The male as well as the female
gonophores have a well-developed umbrella with four radial canals and a ring-canal, and
a large, widely prominent manubrium. That of the androphores (h), or the spermarium,
is more oblong, spindle-shaped, and about twice as long as the ellipsoidal ovarium, or the
manubrium of the gynophores (f). Usually one larger gonophore of each sex, with a very
prolonged manubrium, is prominent from a group of smaller gonophores and of buds.
The special structure of the gonophores is the same as in Hippopodius gleba. (Compare
above, p. 178.)

1 S-J THE VOYAGE OF H.M.S. CHALLENGER.

Subfamily Vogtid^e.

Genus 35. Vogtia,1 Kolliker, 1854.
Vogtia, Kolliker, Schwimmpolypen von Messina, p. 37.

Definition. — Polypkyidae with pentagonal prismatic nectophores, the ostium of which
is provided with five prominent apophyses. (Cormidia monoclinic. Gonophores attached
to the base of the siphons.)

The genus Vogtia, established by Kolliker for the Mediterranean Vogtia pentacantha,
differs from the two preceding genera mainly in the prismatic form of the pentagonal
nectophores. Since this difference is similar to that between Diphyes and Praya, it
perhaps justifies the distinction of two subfamilies : Vogtidas (derived from Diphyidas)
with pentagonal exumbrella of the prismatic nectophores, and Hippopodidse (derived
from Prayidae) with an edgeless exumbrella of the rounded nectophores. Probably the
general composition of the nectosome as well as of the siphosome in Vogtia is similar to that
in Hippopodius. But neither the first description of Kolliker (4), nor the supplementary
remarks of Claus (35), and Keferstein and Ehlers (33), are sufficient to give a full idea of
its anatomy. The last named authors have described a second species, Vogtia spinosa,
from the coast of Brazil (33, p. 24). Similar to this are some scattered nectophores,
which I found in the Challenger collection, taken in the South Atlantic (Station 326) ;
they are here described as Vogtia kblliheri.

Vogtia kollikeri, n. sp. (PI. XXIX. figs. 9-14).

Habitat.— Station 326, South Atlantic; March 3, 1876; lat. 37° 3' S., long.
44° 17' W. Surface.

Nectophores (fig. 9, lateral view, right side ; fig. 10, oblique lateral view, half dorsal,
half right side ; fig. 11, basal view of a younger, fig 12, of an older nectophore; fig. 13,
ventral view; fig. 14, dorsal view). — The nectocalyces have a cartilaginous consistence,
vitreous aspect, and the general form of a flat pentagonal prism. The largest nectophore
has a length of 6 mm., a height of 10 mm., and a breadth of 16 mm. The two large
terminal faces of the prism are nearly parallel and pentagonal, an inferior (and abaxial)
basal face, and a superior (or axial) apical face ; this latter contains the broad ventral or
axial groove, bounded by the two lateral wings. The five lateral faces of the prism are two
paired dorsal, two paired ventro-lateral and an odd medio-ventral face ; this latter is the
smallest face and deeply bisected.

The basal face of the nectophore (fig. 11, of a younger, fig. 12, of an older specimen)
contains in its middle part, nearer the axial side, the ostium of the uectosac (w) ; it is

1 Vogtia, named in honour of Carl Vogt.

REPORT ON THE SIPHONOPHOR^. 183

slightly concave, smooth, and probably directed (as in Hippopodius) obliquely down-
wards and outwards, in the vertical position of the axis of the nectosome. The opposite,
almost parallel, apical face is also smooth, more concave, directed obliquely upwards and
inwards ; it contains the axial groove, which is limited by the two prominent lateral
wings; it passes over downwards into the odd ventral face (fig. 13), which appears
bisected by the lowermost part of the axial groove, limited by the two descending ventral
teeth (the lowermost parts of the two axial wings).

The dorsal face of the nectophore (fig. 14) is convex, broad and depressed, and
bisected by the prominent sagittal crest, which divides it into two paired lateral facettes,
densely covered with conical spines (figs. 11, 12). Two strong paired frontal teeth, with
a triangular spiny outside (fig. 9), separate the two dorso-lateral facettes from the two
ventro-lateral ; these are smaller, rather smooth, and separated one from another below
by the smaller odd ventral face.

The five edges of the prismatic nectophore, which separate its five lateral faces,
correspond to the four edges of the exumbrella of a bUateral Medusa. The odd dorsal
edge, prominent in the sagittal median line of the dorsal face, is strongly dentate. The
opposite ventral edge is divided by the lower part of the axial groove into the two
ventral teeth, which embrace the stem. On both sides, to the right and left, are widely
prominent the two triangular, strongly dentate, lateral apophyses which are placed
at the opposite poles of the frontal axis ; they separate the two dorso-lateral facettes
from the two ventro-lateral faces, and correspond to the two lateral dorsal teeth of
Polyphyes.

The numerous spines which cover the free outside of the nectophores (dorsal and
lateral faces) are mammillate or flatly conical, with a small apical point. Their number
amounts in each nectophore to more than a hundred.

Nectosac. — The subumbrellar cavity is very small, scarcely half as long and broad as
the basal face of the nectophore, of which it occupies the axial or inner half (figs. 11, 12).
Its wide ostium is reniform, with a deep median notch at the ventral side. The muscular
plate of its shallow cavity is weak, the crescentic or sickle-shaped velum is rudimentary
at the ventral side, more developed on the two lateral sides. The nectocalycine duct,
which enters through the axial pedicle into the nectophore, gives off a blind pallia! canal
in its dorsal part (fig. 12, ce), and divides at the top of the nectosac into the four radial
canals ; three of these (the dorsal and the two lateral) are very short ; the fourth (ventral)
canal (cv) is long, and expands near the circular canal in form of a broad two-winged
ventral sinus (figs. 11, 12, cv"). The concave dorsal edge of this sinus is smooth,
whilst the convex ventral edge is much longer, and irregularly denticulate.

184 THE VOYAGE OF H.M.S. CHALLENGER.

Order III. PHYSONECM, Haeckel, 1888.
(Pis. VIII.-XXI.)

Physophoridae, Eschscholtz, 1829, 1, p. 139.
Physophorx, Goldfuss, Auctt.

Definition. — Siphonophorae with a pneumatophore and several nectophores (or instead
of these bracts), without aurophore. Nectosome composed of a simple, apical, mono-
thalamous pneumatocyst, and beyond it a biserial or multiserial group of nectophores,
sometimes instead of these a corona of bracts. Siphosome always with numerous
palpons, usually covered with numerous bracts. The trunk of the siphosome is either a
single siphon (Monogastricaa) or a tubular or vesicular stem, bearing numerous cormidia
(Polygastricse). Each cormidium with a single siphon and a single tentacle, a group of
palpons and gonophores. The cormidia are sometimes ordinate, at other times irregular.

The order Physonectae, hitherto usually called Physophoridae, comprises those very
numerous and variously organised Siphonophorae, which possess a nectosome composed of
an apical pneumatophore and a group of nectophores. They agree in this combination
with the following order Auronectas, but differ from these as well in the absence of the
aurophore as in the simple structure of the tubular trunk. Sometimes the nectophores
are replaced by bracts ; but these are also originally nectophores, with a redueed or lost
nectosac. A further character common to all Physonectae is the general presence of
palpons or cystous ; these are lacking in most other Siphonophorae, with the exception of
the Cystoneetse. The corm of the Physonectae is rarely simple, and represents a single
cormidium (in the monogastric Circalidae and Athoridae) ; usually it is composed of
numerous cormidia, which are sometimes ordinate (with free internodia), at other times
irregular (with scattered organs). The primary larva is always bilateral, and develops a
pneumatophore very early (Physonula).

History. — The oldest descriptions and figures of Physonectae are those of Forskal
(1775), and relate to three Mediterranean forms, which he united in the genus Physo-
phora — Physop>hora hydrostatica, Physophora rosacea, and Physophora filifarmis (11).
The first has been retained as the permanent type of the genus Physop)hora ; the second
was afterwards called by Eschscholtz (1) Atlwrybia, and the third Epibulia; this latter,
however, is a Rhizophysa, and belongs to the Cystoneetse.

In the beginning of the present century the first observations on Physonectae were
made by Peron and Lesueur. In 1807 they published figures of Physophora myzonema
and Stephanomia amphitrites (14, pi. xxix.). An excellent plate by Lesueur, with a
splendid figure of Stephanomia uviformis ( = Apolemopsis uviformis), was unfortunately
never published. Afterwards a number of detached portions of Physonectae, and fragments

REPORT ON THE SIPHONOPHORjE. 185

of corms were described by Quo)' and Gaimard (2, 19, 20) and by Lesson (3, 22) ; but
their figures are so unnatural and incomplete, and their descriptions so superficial and
devoid of scientific understanding of the subject, that they have only produced extra-
ordinary confusion and numerous mistakes.

Eschscholtz, the founder of the System der Acalephen (182(J), first established the
family Physophoiidae, and distinguished it from the other two families of his Siphono-
phorte (Diphyidae and Velellidiu) by this definition : — "The soft body bears at its upper
end a swimming-bladder filled with air." He distinguished (1, p. 141) ten different
genera ; three of these, however, belong to the Cystonectse, and one to the Calyconectse,
so that six remain; of these, Apohmia and Aihorybia are types of two separate famdies ;
Agahna and Stepkomomia belong to the Agalmidse ; Physophora and Discolahe to the
Discolabidie. The system founded by Eschscholtz was much extended, but not advanced,
by Lesson, who in his Acalephes (1843) gave a most confused compilation of all
descriptions published up to his time. Brandt (in 1835) founded the two famdies
Agalmidaj and Anthophysidse (25). The first good anatomical description of a Physonect
was published in 1841 by Milne-Edwards, who illustrated the Mediterranean Stephanomia
( = Forshdia) contorta (71). Another excellent paper on Agalmopsis elegans was
written in 1846 by Sars (27, L).

A more accurate knowledge of the peculiar organisation of the Physonectaa, and a
more natural explanation of their complicated structure, was not acquired before the
sixth decade of this century. At this time Kolliker (4), Vogt (6), Leuckart (5 and 8),
Gegenbaur (7 and 10), and Huxley (9) so greatly advanced our knowledge by a series
of excellent illustrations and accurate descriptions, that most succeeding observers have
only been able to add single particulars. Claus, in his monographs of Physophora
hydrostatica (34), Halistemma tergestinum (74), and Agalmopsis utricularia (75),
advanced mainly our histological knowledge of the Physonectge ; as did afterwards,
more especially, Korotneff (1884), but, unfortunately, without sufficient knowledge of
their morphological and systematic relations (50).

My own observations on the Physonectse were commenced in 1859 in Messina, and
advanced much in 1866 during my residence at Lanzerote in the Canary Islands. I
found here, and stdl more in 1881 in Ceylon, and during my voyage in the Indian
Ocean, the opportunity of examining a number of interesting new forms and even new
types of Physonects (Circalia, Atlwria, Dicymba, Cnjstallodes, Anthemodes, Lychna-
galma, NectaUa, Discolahe, &c, Pis. XI.«-XXL). The Challenger collection, however,
contained only very few specimens of Physonectse which were preserved well enough
for description ; only scattered fragments and detached parts (nectophores, bracts,
siphons, gonophores) were found in many of the bottles.

Kelying on these extended observations, and comparing the numerous scattered
descriptions and figures of former observers, I was enabled to establish the new system

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhlih 24

186 THE VOYAGE OF H.M.S. CHALLENGER.

of Physonects, which I coruinunicated to the Medicin. Naturwiss. Gesellschaft in Jena
on July 8 and November 25, 1887 (95, pp. 38-42). I then gave the definition of
twenty-five different genera (ten of which were new), and disposed them in eight
families, four of which were new. Four families had already been distinguished by
Huxley (9, p. 70), viz.: — (1) Apolemidse; (2) Stephanoinidae ( = Agalnnda3, Brandt); (3)
Physophoridae (sensu restricto) ; and (4) Athorybidse ( = Anthophysidae, Brandt). The
four new families of my system are — (l) Circalidaa ; (2) Athoridaa ; (3) Forskalidae ; and
(4) Nectalidae.

All authors up to this time have employed for this order the name Pkysophoridse,
given by Eschscholtz (1, p. 139). But this name has become unserviceable, since it is
used with no less than four different meanings (95, pp. 38, 41). Huxley applies it to
all Siphonophoraa, with the single exception of the Calycophoridae (9, p. 67). The
majority of authors employ the name in the sense of Eschscholtz, comprising not only
our Physonectae, but also the Cystonectae (fifth order). Chun first separated the latter
from the former, and proposed the term Physophoridae for the first, and Pneumato-
phoridae for the second (86, p. 1168). But, besides, the special family which I call
Discolabicke (XVI.) is generally named Physophoridae. To avoid this general confusion,
I propose for this order the name Physonectae.

Nectosome. — The swimming apparatus is composed in all Physonectae of an apical
float or pneumatophore placed at the top of the trunk, and of a variable number of
nectophores or swimming-bells, arranged in a variable manner around the trunk ; rarely
these nectophores are replaced by paddling bracts (Athoridae, Anthophysidae). The
Physonectae have therefore combined in their locomotive apparatus the active swimming-
bells of the Calyconectae and the passive hydrostatic float of the Cystonectae and
Disconectae. They agree in this combination with the Auronectae, but differ from these
in the absence of the aurophore as well as in the simple tubular trunk and the structure
of the siphosome. The physiological function of the two portions of the nectosome is very
different ; the hydrostatic float is comparable to the swimming-bladder of the fishes, and
enables the Physonectae to rise or descend ; whereas the active movements of the necto-
phores, or the paddling bracts which these replace, effect the voluntary locomotion in
every direction.

Pneumatophore. — The float filled with air, rising from the top of the axial trunk,
is in all Physonectae relatively small ; much smaller than that of the Auronectae and
Cystonectae ; it rarely attains the size of a nectophore (Circalidoj) ; usually it is scarcely
half as large, or less. Whilst the physiological importance of the float rests in its
hydrostatic function (as " swimming-bladder "), its morphological nature is explained by
its development; the pneumatophore is the modified umbrella of the original Medusa,
the manubrium of which is the axial trunk (or the first siphon). (Compare above, p. 11-)
Its form is usually ovate, spindle-shaped or pyriform, sometimes subspherical, at other

REPORT ON THE SIPHONOPHOR^E. 187

times cylindrical ; it is more or less variable, and may be changed by the contraction of
its muscular walls. The apex of the float is usually coloured by pigment (red or brown) ;
sometimes this forms a regular octoradial star, with a colourless centre.

Pi(c>nnatosaccus. — Since the float is developed by an invagination of the original
exumbrella, — comparable to a simple air-secreting gland of the exoderm (p. 12), — the
central air-flask or pneumatocyst, filled with gas, is always surrounded by a double
wall ; the inner or invaginated wall (comparable to the entoderm of a gastrula) is the
pneumatosaccus (or " Luftsack "), which secretes the structureless thin chitin-plate of the
pneumatocyst ; the outer or non-invaginated wall (comparable to the exoderm of a
gastrula) is the pneumatocodon (or " Luftschirm "). The cavity between the two walls
(cavum pneumatophoraB) is everywhere closed and filled with the nutritive fluid of the
axial trunk, with which it communicates at its distal or basal end. This cavity is usually
divided by a number of equidistant vertical septa into radial pouches, which correspond
to those in the umbrella of a Medusa (e.g., JEgina, Cunina). I find constantly eight
radial pouches, regularly disposed around the pneumatosac, in the great majority of the
Physonectse ; the number, however, is not cruite constant ; single individuals have seven
or nine, instead of eight ; some species (Halistemma, Nectalia) possess only four, other
species twelve or sixteen. Sometimes the radial septa divide the whole cavity of the
pneumatophore into chambers, at other times only its basal or inferior part ; this
remains simple in the Athoridse and Apoleniidas, where no septa are developed.

Pneumatocyst. — The delicate chitinous air-flask, which is produced (as a cuticle) and
immediately surrounded by the exodermal invaginated pneumatosac, seems to be closed
in all Physonecta3 at the apex (or the upper pole of its vertical axis) ; it is open at its
thickened annular base (or the lower pole). This opening is the circular pneumatopyle
or funnel aperture (" Trichterpforte," Chun, 48, p. 512). It corresponds to an annular
constriction of the surrounding pneumatosac, by which this is divided into two portions ;
the larger superior (or apical) portion alone secretes the chitinous plate of the flask ; the
smaller inferior (or basal) portion secretes no chitinous cuticle, and has a stratified
exodermal epithebum of a peculiar shape and a yellowish or greenish colour ; this is the
important pneumadenia or the " air- funnel," which secretes the gas (" Lufttrichter,"
Chun, 48, p. 512). The glandular epithelium of the pneumadenia often passes, owing to
a secondary growth and further expansion, through the pneumatopyle into the cavity of
the pneumatocyst and lines its basal portion — usually only one-fourth or one-third of its
inner face (" secondary exoderm," Chun, 48). The pneumadenia is then divided by the
thickened chitinous ring of the pneumatopyle into a superior (endocystal) and an inferior
(hypocystal) portion. At other times the pneumadenia gives off peripheral branches or
lateral solid cord-shaped apophyses which enter into the septa and were formerly described
as peculiar csecal canals by Glaus (74, p. 22) and Korotneff (50, p. 272). This is the ease
in the Discolabidse (Family XVI.) : in these, and perhaps also in other Physonectfe, the

188 THE VOYAGE OF H.M.S. CHALLENGER.

funnel-cavity opens outside by a pore (or stigma) in the median line of the dorsal side,
on the base of the pneumatosac ; the animal can expel the air through this basal
stigma voluntarily (compare 33, p. 3, and 84, p. 35).

Nectophores. — The swimming-bells of the numerous Physonectas exhibit a great
variety in number, form, and arrangement. They appear to be wanting in two families,
the monogastric Athorida? (PI. XXI. fig. 5) and the polygastric Anthophysiche (PL XL);
but in reabty they are here replaced by paddling bracts, which are nothing else than
modified nectophores. One genus only, Dicymba (PL XVIII. fig. 1), has two opposite
nectophores, similar to Diphyes and Praya among the Calyconectse ; and the same con-
dition occurs in the young larvae of Discolabidae (PL XIX. fig. 8), and probably of many
other Physonectaa. Usually the number of nectophores is six to twelve or more, in the
largest forms thirty to fifty or more. They are arranged in two longitudinal opposite
rows in most Apolemidse, all Agalmidae (Pis. XIII. -XVII.), some Nectalidse (Nectalia)
and Discolabidse [Physophora). Some other genera of the two latter families have four
cruciate longitudinal rows (Sphyrophysa and Discolabe, PL XIX.). All Forskalidse
(PL VIII.), and Stephanos-pirn among the Discolabidaa, possess a strobiliform nectosome,
with several spiral rows of nectophores, arranged like the scales of a fir-cone. The
Circalidse (PL XXI. fig. 1), finally, are distinguished by the possession of a horizontal
corona of nectophores radially arranged, similar to that of the Stephalidae (PL VII.
fig. 39). The same arrangement, either in a single horizontal corona, or in several flat,
densely apposed spiral rings, is seen in the numerous bracts of the Athoridae (PL XXI.
fig. 5) and the Anthophysidse (PL XL fig. 1). Sometimes the distal end of these
paddling bracts still possesses a rudimentary nectosac (Athoria, Rhodophysa), and thus
proves its nature as a modified nectophore.

Umbrella of the Nectophores. — The fundamental form of the umbrella in all
Physonectae is bilateral and composed of two symmetrically equal halves (antimeres) ;
but it is at the same time quadriradial, marked by the four radial canals. Usually its
principal axis is more or less obliquely inclined towards the axial trunk, sometimes
almost horizontally ; so that the position of the proximal apex is higher than that of the
distal ostium. The nectophores of most Physonecta? are depressed and shortened in the
dorso-ventral direction, so that the sagittal axis is shorter than the frontal. Usually
there arise from the truncate apex two lateral horns or wings, which embrace the trunk.
The ventral (or inferior) face of the umbrella has a concave groove, and from its middle
line, near the apex, arises the short pedicle which attaches it to the stem. More rarely
(in the strobiliform nectosome of the Forskalida?) the pedicle is longer than the
nectophore and arises from the very apex. The jelly-substance of the umbrella is usually
rather consistent and firm, sometimes almost cartilaginous.

Nectosac. — The muscular subumbrella of the swimming-bells is of very variable size
and form, sometimes little smaller than the umbrella, at other times scarcely half as

REPORT ON THE SIPHONOPHORyF 189

large. Usually its form is also bilaterally symmetrical, and often divided into three
portions ; an odd narrow basal part, and two paired apical wings. The pedicular canal,
coming from the cavity of the trunk, divides at the top of the subumbrella into four
radial canals. Usually the two sagittal canals (shorter ventral and longer dorsal) have a
simply curved course in the median plane of the subumbrella, whilst the two paired
lateral canals right and left) are much longer and form several loops. The circular ring-
canal, which connects the four radial canals on the ostium of the nectosac above the
velum, is usually small. Many Physonectse bear a red or brown pigment-spot
(ocellus, ' the point where the radial canals open into the ring-canal. But usually
only the two lateral canals, or the dorsal also, exhibit this ocellus, whilst the ventral
canal has lost it (PL XVIII. fig. 9).

Sijyhosome. — The Physonectse exhibit very great differences in the form of the
siphosome and in its composition from various parts. Accordingly three principal groups
(or suborders) may be distinguished in that great order, the Siphostelia, Macrostelia, and
Brachystelia. The first group, Siphostelia, are the monogastric Physonectse (Circalidse
and Athoridse, PI. XXI.) ; the axial trunk is represented by a single central siphon ;
from the superior or basal part of this (as from the manubrium of a budding Medusa)
arise the buds of the various medusomes, which compose the single cormidium. The two
other suborders are polygastric, therefore their corm is composed of numerous cormidia.
The second group, Macrostelia, has a long tubular trunk of the siphosome, much longer
than that of the nectosome, and the siphons of the cormidia are separated by long
internodes (Apolemidse, Agalmidse, and Forskalidse, Pis. VIII., XIV., XVIII. ). The
third group, Brachystelia, on the other hand, possesses a short vesicular trunk of the
siphosome, either a flat sac or a spirally convoluted bladder, and the cormidia are densely
apposed one to another, with very short internodes (Nectalidse, Discolabidse, and
Anthophysidse, Pis. XL, XIII. , XIX., XX.).

The long tubular siphosome of the Macrostelia is very extensible and contractile,
and exhibits in the most contracted state (PL IX. fig. 6) the same appearance which the
Brachystelia offer permanently. The long internodes of the former (similar to those of
the Calyconectaa) are extremely shortened in the latter. The insertion of the cormidia,
however, and of the single parts composing them, is the same in both groups. All
parts arise originally by budding from the ventral median line of the trunk, in the same
way as the nectophores from the ventral line of the trunk of the nectosome. But when
the trunk becomes spirally twisted, then the direction of the spiral turning is usually or
always opposite in the two portions of the corm ; the spiral of the nectosome is mostly
left-handed or lambdoidal (like that of the spiral cnidobands in the tentilla) ; the spiral
of the siphosome, however, is usually right-handed or deltoidal. The cavity of the axial
trunk is continuous in both portions. The original situation of the ordinate cormidia,
succeeding at equal distances in the straight median ventral lino of the trunk, is

190 THE VOYAGE OF H.M.S. CHALLENGED.

permanent in two remarkable genera of the Agalmidse, Crystallodes (PI. XVII.) and
Stephanomia (Amphitrites, Peron). The horizontally swimming trunk is here so densely
covered with thick prismatic bracts, that it becomes rigid and almost every contraction
is excluded, no spiral turning possible.

Cormidia. — The arrangement of the polymorphous medusomes in the Physonectse,
their composition and metameric succession along the stem, offer numerous important
modifications, hitherto much neglected. The general opinion has been up to this time,
that in most Physonectse the polymorphous persons and their organs are intermingled
without definite order, and that only in a few cases, as in Apolemia and PhysopJiora,
they may be disposed according to certain laws, as in the Calyconectse (8, p. 311, &c).
But in reality the reverse is the case. The great majority of Physonectse possess ordinate
cormidia, and in the minority only irregular cormidia with more or less scattered parts
occur. The cormidia are ordinate and separated by free internodes of equal length in the
Apolemidfe, and Stephanomidse (the first subfamily of Agalmidse) ; they are also ordinate,
but separated by narrow internodes or constrictions of the trunk, in the Nectalidse,
Discolabidse, and Anthophysidse. On the other, hand the cormidia are irregularly
placed, and the polymorphous parts scattered along the stem, in the Forskalidse (except
Strobalia) and the Halistemmidse (the second subfamily of Agalmidse).

The cormidia of nearly all Physonectee are monogastric, with a single siphon and a
single tentacle attached to each node of the trunk. A single exception is formed by
Apolemia and the closely allied Ajiolemopsis ; these possess two to four or more siphons
in each ordinate cormidium, and the same number of tentacles.

Bracts. — Nearly all Physonectse possess a great number of hydrophyllia, bracts or
covering scales ; they are wanting in two families only, the Cirealidse and the Discola-
bidse ; in the latter they are probably lost by phylogenetic reduction. Usually the
bracts cover the entire stem in hundreds or thousands, and arise not only from the
nodes of the siphosome, but also from the internodes between them ; or even from the
pedicles of the siphons (Forskalidse) ; but sometimes they arise only from the nodes.
Their general function is that of protective organs, or shields, which cover the other parts
of the corm ; in two families, however, the Athoridse and Anthophysidse, where necto-
phores are wanting, the bracts take on besides a locomotor function and become paddling
organs (PI. XXI. fig. 5 ; PI. XI. fig. 1). Sometimes the distal end of the bract in this
case encloses a small rudimentary subumbrella, and is thus proved to be developed from
a reduced nectophore (PI. XXI. fig. 6). At other times it is possible that each bract
may not be homologous with a complete umbrella, but a separate portion of a cleft (e.g.,
quadripartite) umbrella. Their jelly-substance is always colourless, hyaline, and trans-
parent, usually rather firm, often cartilaginous. Their form is extremely variable. The
bracts in the majority of Physonectee are rather thin scales, lanceolate or triangular
plates, more or less foliaceous or squamiform, with a convex upper (or dorsal) and a

REPORT ON THE SIPHONOPHOR.E. 191

concave lower (or ventral) .side ; the proximal end being attached to the trunk by a short
pedicle, which can be raised and lowered by a muscle. The peripheral margin is usually
thin, often with a few teeth. Sometimes the dorsal face is provided with a prominent
median crest, or a number of parallel or divergent ribs (three to five or more) which are
armed with cnidocysts and prominent at the distal end as free teeth. More rarely the
bracts are very thick and compact, either roundish clubs (in the Apolemidse) or prismatic
bodies (in the Crystallodinse). In these latter they are so thick and densely apposed one
to another, that the movable stem loses its contractility and the siphosome becomes rigid.
Each bract contains a simple canal, which arises from the trunk, runs along the ventral
side of the bracts (usually in the median line), and ends blindly near to its distal end.

Siphons. — The Physonectaj have usually large and well-developed siphons, in which
the four usual portions or segments may be distinguished ; these exhibit, however,
a rather various development in the different groups. The pedicle, or the first portion,
is usually a short cylindrical tubule ; but it is longer in some Agalniidse, and very
prolonged (similar to a very long lateral branch of the trunk) in the Forskalidaa. The
basigaster, the second segment, is usually small, hemispherical or ovate, with a narrow
cavity and a thickened exodermal wall, full of cuidocysts ; it is often elongated and
pyriform, in the Brachystelia (mainly in the Discolabidaa). The true stomach, or third
portion of the siphon, is usually the largest part, with a wide and very extensible
cavity, the exoderm of which is very muscular, the entoderm glandular. The hepatic
glands are usually developed in the form of long parallel hepatic ridges, more rarely in
the form of numerous scattered hepatic villi, as in the Athoridse and Brachystelia
(Nectalida?, Discolabidaa, Anthophysidse), also in the gigantic Bathtjphysa among the
Forskalidaa. There is, however, no sharp boundary between these two forms of
liver ; sometimes the hepatic villi are arranged in regular longitudinal series and thus
pass over into true liver-ridges (" Leberstreifen "). The number of the latter is usually
eight, more rarely four, six, twelve, or sixteen ; sometimes four larger perradial ridges
alternate regularly with four .smaller interradial, and between these are interpolated
eight shorter adradial ridges (PI. IX. fig. 7). The proboscis, or fourth and last portion of
the siphon, is usually a cylindrical, very mobile and contractile tube ; its distal mouth
opening may be expanded in the form of a very large and thin suctorial disc, sometimes
circular, at other times polygonal, often octagonal or square. The edge of the mouth
is usually armed with peculiar cnidoblasts and palpoblasts. The outside of the siphon
is often covered with vibratile epithelium, especially the proboscis.

Tentacles. — Each siphon bears a single tentacle attached to its basal portion, either to
the distal part of the pedicle, or to the basigaster itself, often in a constriction between
them. The tentacles in all Pkysonectas are very kmg and contractile, cylindrical,
tubular filaments, of the same structure as the trunk, with an outer strong layer of
exodermal longitudinal muscles, and an inner thin layer of entodermal circular muscles.

192 THE VOYAGE OF H.M.S. CHALLENGER.

They are simple in one family only, the Apolemidse. In all the other families they bear
a series of equidistant lateral branches or tentilla. These are rarely quite simple secondary
filaments (Circalia). Usually each tentillum is divided into three portions, a basal
pedicle, an intermediate cnidoband, and a terminal filament ; this latter is either simple
or multiple. The greatest variety of structure and form is exhibited by the middle part,
the cnidoband (sacculus, " Nesselknopf "), and this presents the chief characters for the
distinction of genera. The basal pedicle is always a simple cylindrical tubule, often
dilated or vesicular at the distal end.

The cnidoband or cnidonode (cnidosac, sacculus, "Nesselknopf"), the middle and most
important portion of the tentillum, is originally nothing more than a dilatation of the
middle part of the simple filiform and tubular tentillum, produced by the undateral
development of larger cnidocysts in its wall. Then follows the dislocation of the
central canal, which becomes excentrically placed ; next a bilateral form, and soon a
spiral twisting of the dilated portion. That side, in which the excentric canal runs, is
the ventral side of the cnidoband, the opposite, in which the cnidobattery (or the accumu-
lation of larger cnidocysts) is placed, is the dorsal side. Between them is developed the
elastic " angleband," a group of two or four parallel elastic ribands. The excentric canal,
also more or less coiled, runs in the axis around which the cnidoband is twisted. The
spiral is always a left-handed, or lambdoidal. The cnidocysts which compose the cnido-
battery are usually of two kinds, very numerous small and paliform, and a smaller number
of large ovate or ensiform thread-cells ; the latter are arranged usually in two lateral rows
on the proximal part of the cnidobattery.

The spiral cnidoband is usually coiled up in three or four left-handed turnings ; but
sometimes it makes six to eight turnings or even more. It remains naked, without
involucrum, in Athoria (PL XXI. fig. 8), Halistemma, the Forskalidai (PI. X. fig. 23) and
in part of the Anthophysidse (Rhodophysa). In the majority of the Pkysonectse there
is developed around its proximal end a peculiar involucrum, covering it like a cap or
hood ; it is a solid annular fold of the exoderm, which arises from the distal end of the
pedicle and grows distally. Claus maintains that this envelope " evidently corresponds
in morphological relation to the umbrella of a Medusa " (74, p. 2) ; but their likeness
is merely external. The involucrum is nothing more than a simple protecting mantle for
the naked cnidoband. At first it envelops the proximal base only (Stephanomia,
Ci^ulita, Anthemodes, PI. XV. fig. 11, &c), but afterwards it grows around the entire
cnidoband and envelops it distally as an external capsule. The most complicated structure
is exhibited by the involucrum in the Discolabidaa ; where it often bears a pair of red
lateral ocelli (PI. XX. fig. 14) ; the convex dorsal side is here so strongly developed,
prolonged and much twisted, that the cnidoband is recurved and its distal end placed
near the proximal base on the contracted ventral side ; the terminal filament becomes
reduced in this case and finally disappears.

REPOKT ON THE SIPHONOPHORJE. 193

The simple terminal filament is permanent in the majority of the Physonectae (in all
Forskalidse, a great part of the Agalmidse, Stephanomia, Anthemodes, PI. XV. fig. 11,
Cupulita, &c.), some Anthophysidae, &c. But in another great part of the genera it
becomes trifid and developed in the form of three terminal appendages, an odd median
vesicle (or terminal ampulla) and two paired lateral filaments or horns (Crystallodes,
PI. XVII. figs. 4, 5, Agalma, PI. XVIII. fig. 14, Agalmopsis, &c). To these three
appendages is added in Athorybia a peculiar conical solid appendage, a dorsal spur
(PI. XII. figs. 12, 13, tf), and in the closely allied Antlwphysa a pair of two lateral
palmate appendages on the dorsal side. The remarkable Agalmid Lyclmagalma is
distinguished by a large hydrostatic terminal ampulla, and a corona of eight radial
filaments surrounding it (PL XVI. figs. 1, 9).

Palpons. — Hydrocysts or tasters are generally present in all Physonectse, and usually
in far greater number than the siphons, so that each cormidium possesses a group of
several palpons (PI. XII. figs. 7-9, q ; PI. XVIII. fig. 2, q, &c). The true palpons or
tasters are, however, often confounded with other organs, especially with the cystons
and even with the tentacles (Glaus, 34, 35, Sec). The true palpons are mouthless, cylin-
drical, pyriform or spindle-shaped tubes, which morphologically correspond to the
manubrium of a Medusa, but not to the tentacle. They differ from the siphons as well
as from the cystons, in the absence of a distal opening ; also from the former in the
simpler structure of their thin very contractile wall, and especially in the absence of
hepatic glands, and of a basigaster. Sometimes, however, two annular constrictions are
more or less distinct, so that a short pedicle, a middle main part and a distal appendage
or terminal ampulla may be distinguished. The latter often exhibits various structures,
an accumulation of terminal cnidocysts, of pigment, of palpoblasts, &c. The main function
of this distal part seems to be sensory, mainly feeling; sometimes an ocellus is developed
on its dorsal side, provided in some species with a small lens (PI. XI. fig. 4, qo) ; at
other times the spherical distal end is separated by a constriction from the main part
and contains a group of crystals or concretions, rotated by vibratile epithelium, thus
resembling an otocyst. The largest palpons are developed in the Discolabidaa (PI. XIX.
fig. 1), where they replace the missing bracts ; they form at the proximal end of the
siphosome a corona of very large and thick- walled protecting tubes, which are at the
same time vigorous capturing arms ; each ordinate cormidium possesses either two
palpons (Physophora) or a single large one (Discolabe). Another part of the palpons
has a direct relation to the gonophores, and the gonostyles may be originally always
sexual palpons. These latter have often a peculiar structure and may be distinguished
as gonopalpons. Those corrns of the Physonectaa which have ordinate cormidia usually
possess a constant number of palpons attached above the base of the siphon ; in those
corms, however, in which the cormidia are dissolved, usually very numerous palpons are
scattered along the whole trunk of the siphosome.

[ZOOL. CHALL. EXP. PART LXXVII. — 1888.) Hhhh 25

194 THE VOYAGE OF H.M.S. CHALLENGER.

Cystous. — Numerous Physonectse, mainly the Macrostelia (Apolernidse, Agalmidse,
and Forskalidae), possess cystons or anal vesicles, excretory polypites which occur in no
other order of Siphonophorse. They have hitherto been confounded with the similar
palpons, although some authors have observed the distal opening, by which fluid and
crystalline excretions are ejected. The cystons differ from the similar but smaller
palpons essentially in the possession of the distal opening, which may be closed by a
muscular sphincter, and with respect to its function called an anus (PI. XV. figs. 8, 9, yo).
They seem to differ further in the peculiar structure of the wall, which is often intensely
coloured (PI. XVIII. fig. 2, y) and glandular, at least in the distal part. The characteristic
hepatic glands of the siphons, however, are wanting. The cystons are therefore excretory
polypites, which in morphological relations are intermediate between the digesting
siphons and the feeling palpons. I have never observed more than a single cyston in
each monogastric cormidium. In the polygastric cormidia of the Apolemidse the number
of cystons seems to correspond to that of the siphons.

Palpacles. — Usually in the Physonectse each single palpon, as well as cyston, is
provided at its base with a long palpacle, or a simple "accessory tentacle." It is a very
slender, never branched, cylindrical tubule, the thin wall of which contains small
cnidoblasts and palpoblasts. It is in perpetual motion, and its function is mainly
sensory. Perhaps these feeling filaments (" Tastfaden" ) are generally distributed among
the Physonectse; they are not observed in various genera, but it may be possible that
here they have been either overlooked or lost accidentally.

Gonodendra. — Nearly all the Physonectse have monoecious corms, male and female
gonodendra being developed from the same trunk. There are two exceptions only where
the corms are dioecious : — Athoralia among the monogastric, and AjJolernia among the
polygastric Physonects ; in these two genera each corm bears either male or female
gonodendra.

The ordinate cormidia are usually monoclinic, each provided with two gonodendra, a
male and a female, which arise separately from the node of the trunk (PI. XVIII. fig. 2 ;
PL XX. figs. 9-16). Usually here the female is placed more proximally (near the palpon)
and the male more distally (near the siphon). These gonodendra may be called distylic,
since their stems or gonostyles are two independent branched palpons. There occur,
however, sometimes monostylic gonodendra, where the basal part of the single branched
gonostyle bears female, and the distal part male gonophores. This is the case in
Forskalia (PL X. fig. 21 ; compare Kolliker, 4, Tab. ii. fig. 1).

The irregular cormidia are sometimes monoclinic, at other times diclinic ; in the
former male and female gonodendra occur scattered over the same internode ; in the
latter arising separately from different internodes. In many Physonectse with irregular
cormidia (mainly Halistemmidse) very numerous gonodendra of both sexes are scattered
irregularly along the whole trunk.

REPORT ON THE SIPHONOPHORiE. 195

Gonostyles. — The stems of the gonodendra, which bear the clustered gonophores, and
which we call gonostyles, are sometimes themselves simple palpons, at other times
branches of sexual palpons, or in a peculiar manner combined with sterile palpons. The
ramification is in most Physonectae not very rich (mainly in the males), and not to be
compared with that of the Cystonectse. There are, however, exceptions, as in the female
gonodendra of some Discolabidse (PI. XX. figs. 11-16). The male gonostyles of the latter
exhibit a peculiar appearance, since their distal part, after the detachment of the ripe
androphores, is covered with tubercles (as the remaining pedicles of the latter), whilst the
proximal part produces vicarious gonophores.

Gonophores. — The medusiform gonophores of the Physonectae are in general of small
size, especially the females. Their umbrella is sometimes well developed, with four
equidistant radial canals and a marginal ring-canal, whilst at other times it is more or
less reduced, and sometimes rudimentary. The manubrium is larger in the androphores,
where it is usually club-shaped or cylindrical, with a central spadix ; often coloured
white, yellow, or red ; it is often very prominent from the narrow mouth of the reduced
umbrella (PI. XII. fig. 17 ; PI. XVIII. fig. 17, &c). The manubrium of the gynophores
is much smaller, ovate or subspherical, and develops constantly a single large ovum only.
This is often surrounded by an irregular network of peculiar anastomosing canals
(PI. XV. fig. 15; PI. XVIII. fig. 16). These " spadicine canals" arise by a peculiar
process : the original central spadix in the axis of the young ovarium becomes excentric
by the undateral development of a single large ovum ; it grows around the latter in the
form of a hemispherical cup, and envelops it finally like a capsule ; by the partial
irregular concrescence of its two walls arises the reticulum of canals, which is called
" netzformiges Canal-System" by German authors.1

Ontogeny. — The development of the fertilised egg is hitherto known in the case of
only very few Physonectae. The first observations on it were made by myself in the
Canary Island Lanzerote, in December 1866, and January and February 1867. I was
able to observe there the embryonic development and the metamorphosis of Pliysophora
magnified,, Crystattodes rigida, and Athorybia ocellata (84, Tafs. i.^xiv.). Further
observations were published in 1874 by Metschnikoff, who illustrated the ontogeny of
TIalistemma rubrum, Cupidita picta, and Agalmopsis sarsii (85, Tafs. viii.-xii.).
The embryology of Agalma elegans was afterwards described by Fewkes (89, pis. i.-iv.).
Judging from these few observations, it seems that the Physonectae are subject to a
rather complicated metamorphosis and produce medusiform larvae, the morphological
value of which is probably very great for their phylogeny. Usually these monogastric
larvse (Physonida) develop the pneumatophore from their exumbrella very early, and
around it a corona of provisional bracts. (Compare Famdy XL, Athoridae, p. 200, and PI.
XXI. figs. 5-13.)

1 Compare TVeismami, Die Entstehung der Sexual-Zellen bei den Hydromedusen, 1883, p. 206.

190

THE VOYAGE OF H.M.S. CHALLENGER.

Synop>sis of the Eight Families of Physonectse.

ravsoNECTj; monogastricje, with a single
siphon and a single tentacle (Sipho-
stelia).

Siphosome with a
long tubular stem,
longer than the
axis of the neeto-

Physonects poly- s.Te, (Macr°-

GASTRIC*), With

numerous siphons, ,

each of which is '

provided with a

tentacle.

Siphosome with a

short vesicular

stem, shorter than <

the axis of the '

nectosome (Bra-

chystelia).

Nectosome with a corona of nectophores,
without bracts, .....

Nectosome with a corona of bracts, without
nectophores, .....

Nectosome biserial,
with two opposite
rows of necto
phores.

Pneumatophore with-
out radial pouches.
Tentacles simple,

Pneumatophore with
radial pouches.
Tentaclesbranched,

Nectosome multiserial, strobiliform, with
several spiral rows of nectophores,

Nectosome with two,
four, or more rows
of nectophores.

Siphosome with a
corona of bracts, .

Siphosome without
bracts,

Nectosome without nectophores, instead of
these a corona of bracts,

10. Circalidae.

11. Athoridae.

12. Apolemidw.

13. AgalniidaB.

14. Forskalid*.

15. Nectalidae.

16. Discolabidae.

17. Anthophysidw.

Family X. Circalidae, Haeckel, 1888.

Circalida:, Hkl., System der Siphonophoren, p. 38.

Definition. — Physonectse monogastricas without bracts, with a corona of nectophores
which surrounds the pneumatophore, and a corona of palpons which surrounds the base of
the single siphon and the single tentacle. Pneurnatophore with radial pouches.

The family Circalidae is founded by me for the new genus Circalia, and comprises
those monogastric Physonectse which possess an upper corona of nectophores around the
apical pneumatophore, and a lower corona of palpons around the basal siphon. They are
similar to the polygastric Discolabidae, and may be compared to a Stephanospira which
has developed a single siphon only and a single spiral row of nectophores.

The single specimen of Circalia which I have been able to examine living was
observed by me in September 1869 on the west coast of Norway, off the mouth of Sogne
Fjord ; it is figured in PI. XXI. figs. 1-4. But perhaps there belongs to the same genus
(or forms a new closely allied genus) another, larger, monogastric Physonect, which was
captured in August 1826 by Captain Dumont d'Urville in the Atlantic Ocean (lat.
30° S., long. 15° E.). It is described and figured by Quoy and Gaimard under the name
PhysopJiora alba.1 L. Agassiz afterwards established for it the genus Haplorhiza (a
name previously employed for a Rhizostomid) (36, p. 368). According to the description
1 Voyage de "l'Astrolabe " (Zoophytes), p. 53, pi. i. figs. 1-9.

REPORT ON THE SIPHONOPHORiE. 107

of the French observers, the apical pneumatophore was surrounded by a corona of five
nectophores, and the single large basal siphon by a corona of numerous palpons ; two
tentacles are figured, but probably these were only parts of a loop of a single one. The
tentilla, however, arranged in a single long series along the tentacle, were not simple-
lateral branches as in our Circalia stephanoma, but provided with an ovate cnidosac at
the distal end. It is possible, therefore, that this Circalia haplorhiza represents another
genus of Circalidse ; it may be called provisionally Circonalia.

Another monogastric Physonect, which is very similar to Circalia, and inhabits the
western part of the Gulf Stream (near the Tortugas Reefs, Florida), has recently been
described by Fewkes under the name Agalma papillosum. Its nectophores are
papillate, and the tentilla, which form a long series on the single tentacle, are tricornuate
with a median terminal ampulla and two lateral horns at the distal end of the spiral
cnidoband (as in Agalma, Agahnopsis, &c). But since no gonophores were observed on
this remarkable form, it is perhaps only the larva of another Physonect.

The single cormidium, which represents the mature corm of Circalia, is of great
interest on account of its typical simplicity and its morphological relations to other
Siphonanths, especially to the Discolabidae (Physophora, Stephanospira) on one hand, and
to the Rhodalidas (Stephalia, Rhodalia) on the other hand. The entire cormidium may
be compared with a Medusa, which has preserved the original simple manubrium (the
central siphon), but whose umbrella has been transformed into a pneumatophore, and
produced by budding (from the base of the manubrium) a corona of radial medusomes
(eight in Circalia stephanoma), each medusome being composed of a proximal nectophore
and a distal palpon (or a pair of palpons), and beyond this a gonodendron.

It is perhaps a fact of great morphological value, that the octoradial type of
Medusa in Circalia is expressed not only in the structure of the pneumatophore (with
eight radial pouches of the cavity, and eight pigment-rays at the apex), and of the
single central siphon (with eight liver-ridges and eight mouth-lobes), but also in the
composition of the nectosome (with eight radial nectophores) and of the siphosome
(with sixteen palpons and eight gonodendra) ; these latter numbers, however, may be
accidental.

Comparing the entire corm of Circalia with a single Medusa, which has produced
a cormidium by budding from the base of the manubrium, we get a further support for
our medusome theory (p. 3). The transformed umbrella of the original Medusa person
is the apical pneumatophore ; its manubrium is the prolonged central siphon. The
distal and lower part of the siphon only has preserved the function of a feeding and
digesting stomach, whilst the proximal and upper part represents the axial trunk of the
corm, from which the buds arise. These buds may have been originally simple Medusae,
but afterwards transformed into loose medusomes ; the umbrella of the secondary
Medusa has been developed into a nectophore, the dislocated manubrium into a palporj,

198 THE VOYAGE OF H.M.S. CHALLENGER.

and its single tentacle into a palpacle. Beyond these sterile medusomes have been
developed the fertile ones, in the form of gonostyles, which have produced by budding
the gonodendra composed of numerous Medusoid gonophores.

Genus 36. Circalia,1 Haeckel, 1888.
Circalia, Hkl., System der Siphonophoren, p. 38.

Definition. — Circalidae with a single corona of nectophores radially arranged around
the pneumatophore, and with a series of simple filiform tentilla on the single tentacle.

The genus Circalia (PI. XXI. figs. 1-4), as the single known genus of Circalidffi,
possesses the characters of the family described above. As a peculiar character of the
genus may be pointed out the remarkable composition of the corona of (eight) radial
nectophores, similar to that of Stephalia (PL VII. figs. 39, 48). Another character of
generic value may be the simple tubular shape of the tentilla, or the filiform lateral
branches of the single tentacle (similar to Nectophysa wyvillei, PL XXIII. fig. 5). It
differs in this from the similar Circonalia haplorhiza ( = Physophora alba, Qnoy and
Gaimard, 2). Compare above, p. 197.

Circalia stephanoma, n. sp. (PL XXI. figs. 1-4).

Habitat. — North Atlantic, west coast of Norway, near the Sogne Fjord ; September
1869 (Haeckel).

Nectosome. — The swimming apparatus has a diameter of about 5 mm., and is composed
of a large apical pneumatophore and a corona of eight nectophores radially arranged
around it. These are attached by short ventral pedicles to a central axial trunk, the
uppermost dilated part of which is the pneumatophore, whilst the lower part of the
trunk passes over directly into the base of the siphon. From the dorsal side of the latter
arises the single tentacle, whilst in the median line of the opposite ventral side (between
the two ventral nectophores) a small group of young buds is visible.

Pneumatophore. — The float at the apex of the trunk is pyriform or subspherical,
of about the same size as the nectophores (2 or 3 mm. in diameter). Its apex bears
a ventral depression or umbilicus (perhaps the closed opening ?) and around this a red-
brown pigment-star, composed of eight equidistant triangular rays. The basal half exhibits
eight longitudinal grooves, the insertions of the radial septa which divide the cavity of
the pneumatophore into eight radial pouches (fig. 4, pq, in horizontal transverse section).

Nectophores (figs. 1, 2, n). — The eight swimming-bells which compose the octoradial
corona around the central pneumatophore are of rather regular campanulate form.

1 Circalia = Marine corona, Ki'fixo;, aTuoj.

REPOKT ON THE SIPHONOPHOR^E. 199

Their principal axis is longer than the transverse axis, and is directed obliquely from
above downwards and outwards. The dorsal or superior face is convex in the proximal,
concave in the distal part. The opposed ventral or inferior face is more concave, with
a ridge in the middle line ; from the upper or apical part of this ridge arises the short
pedicle which attaches the nectophore to the axial trunk. Their jelly-umbrella is rather
thin, but firm. The nectosac is large ; its four equidistant radial canals are of nearly
equal length and run in a simple curve (without loops) from the top of the subumbrella
(where the pedicular canal enters) towards the basal ostium ; they are here united by a
circular ring-canal, above the small velum.

Siphosome. — The basal part of the monogastric corm, below the nectosome, is composed
of a single, very large central siphon, and a corona of numerous palpons which surround
its proximal base ; each palpon bears a simple palpacle, whilst the siphon bears at its
dorsal side a single very long tentacle, beset with a row of numerous tentilla. The basal
part of the siphon, immediately below the palpons, is surrounded by a corona of gono-
phores. The diameter of the siphosome in the expanded state is about 10 mm.

Siphon (s). — The large central polypite, which represents the axial trunk of the
monogastric corm, is divided into four segments. The first and uppermost segment,
comparable to the pedicle of the siphons of the polygastric Siphonanthse, is a cylindrical
vertical tube, to which are attached three coronas ; the upper corona composed of necto-
phores, the middle of palpons, and the lower of gonophores. Below this follows the
second segment, corresponding to the basigaster, a small ovate dilatation with a thickened
wall full of cnidocysts. The third segment is the large spindle-shaped stomach, the
wall of which exhibits eight equidistant red-brown villous hepatic ridges (sh). The fourth
and last segment is the distal proboscis (sr), a very contractile cylindrical tube with
eight strong longitudinal muscle-bands. Its terminal mouth opening exhibits eight
rounded radial lobes (ss).

Tentacle (t). — The single large tentacle, which arises from the base of the siphon on
its dorsal side, is a very long cylindrical tube, furnished with a single series of very
numerous tentilla (ts) ; these are simple thin lateral branches of the tentacle, densely
covered with small ovate cnidocysts. The structure of the tentacle is similar to that of
Nectophysa wyvillei (PI. XXIII. figs. 5, 6).

Patyons (q) and Palpacles (r). — The corona of palpons which is expanded around the
base of the siphosome, immediately below the nectosome, is very similar to that of the
Discolabidse. It is composed (in the single specimen observed) of sixteen to twenty —
or perhaps more — cylindrical tubular palpons, tapering towards the two ends ; the
proximal end is rounded and attached by a short and thin pedicle to the axial trunk ;
the distal end is closed, pointed, and armed with a group of cnidocysts. From the dorsal
side of the basal pedicle arises a long and very movable palpacle, a thin cylindrical
tubule, the wall of which contains small cnidocysts.

200 THE VOYAGE OF H.M.S. CHALLENGER.

Gonodendra. — The corm is monoecious and monoclinic, and bears numerous gono-
phores of both sexes, densely crowded beyond the corona of palpons, and forming an
inner corona around the base of the siphon. At the first glance I supposed that this
corona was composed of two large gonodendra only, a male and a female. A closer
examination, however, of the well-preserved spirit specimen, informed me that it was
composed of eight small gonodendra, four males (fig. 3, h) and four females (fig. 3, /)
alternating. The umbrella is well developed in both sexes, with four radial canals and a
ring-canal. Each gynophore contains a single large ovum, each androphore a club-
shaped spermarium with a central spadix.

Family XL Athoeid^, Haeckel, 1888.

Athoridx, Hkl., System der Siphonophoren, p. 38.

Definition. — Physonectse monogastricae without nectophores, with a corona of
bracts which surrounds the pneumatophore, and a corona of palpons which surrounds
the base of the single siphon and the single tentacle. Pneumatophore without radial
pouches.

The family Athorida? comprises some small, hitherto undescribed Physonectae, which
are in general similar to Athorybia or Anthophysa, but differ essentially from them in
the possession of only a single siphon. They agree with these Anthophysidaa (Family
XVII.) in the absence of nectophores, which are replaced by a corona of bracts. On the
other hand, they are similar to those well known Athorula-larvse, or " Athorybia-like
larvse," which are develojied from the fertilised egg of certain Physonectae, especially
Agalmkke. Compare Vogt (6, pi. x. figs. 32-37), Gegenbaur (7, Taf. xvii. fig. 11),
Claus (35, p. 557, Taf. xlviii.), Haeckel (84, Tafs. vii., viii., ix., fig. 60), Metschnikoff
(85, Tafs. ix., xi.), Fewkes (89, pi. iv.).

The resemblance of the monogastric Athoridaa to these larvae of polygastric Agalmidae,
and the morphological likeness of their structure, make it probable that the former are
either remnants of the ancestral forms of the latter, or that they are larval forms which
under certain conditions sometimes attain sexual maturity (Psedogenesis). A further
accurate examination of these interesting small Physonects, and a complete knowledge of
their anatomy as well as ontogeny are required to recognise their relations to the other
families of this order.

Two different forms of Athoridae were observed by me in 1881 during my residence
in Ceylon. The first and larger, Athoralia coronula, was very similar to a small young
Athorybia (Pis. XL, XII.); it will be described on another occasion. The second and
smaller form is described in the sequel as Athoria larvalis (PL XXI. figs. 5-8); it
differs from the former in the possession of a small rudimentary nectosac at the distal

REPORT OST THE SIPHONOPHOR^E. 201

end of the bracts, similar to that which is found in some Athorula larvae of Aealmidae
(PI. XXI. figs. 7, 10, 12). Another similar form, but with more numerous and slender
bracts, was found in a preparation in the Challenger collection (Athoria bractealis).
It was insufficiently preserved. Possibly these small and delicate Physonects have already
been seen by former observers, but regarded as mere larvae.

The entire corm of these monogastric Athoridse represents a single cormidium, and
may be regarded as a medusome, the umbrella of which is the pneumatophore, and the
manubrium the central siphon. From the proximal base of the latter is produced by
budding a corona of secondary medusomes ; each of these is again composed of a
modified umbrella (the bract) and a manubrium (the palpon) ; the palpacle, which is
attached to the base of each palpon, is the persistent tentacle. The gonophores, which
are developed beyond the palpons, represent a second corona of medusomes, which
become sexually mature. The small nectosac which occupies the distal end of the bracts
in Athoria is of special interest, since it demonstrates that the bracts are modified
umbrellas.

Synopsis of the Genera of Athoridse.

Bracts with a rudimentary nectosac on the distal end. Corms monoecious. Tentilla without

involucrum, .......... 37. Athoria.

Bracts without rudimentary nectosac. Corms dioecious. Tentilla with an involucrate

cnidoband, .......... 38. Athoralia.

Genus 37. Athoria,1 Haeckel, 1888.
Athoria, Hkl., System der Siphonophoren, p. 39.

Definition. — Athoriche with a rudimentary nectosac at the distal end of the bracts.
Tentilla with a naked spiral cnidoband, without involucrum. Corms monoecious.

The genus Athoria is remarkable for the possession of a rudimentary subumbrella, a
small campanulate nectosac at the distal end of the bracts ; its mouth is armed with four
groups of cnidocysts which may be regarded as small rudiments of tentacles. They
agree in this character with the genus Rhodojihysa among the Anthophysidae (Genus 58)
and with the Athorula larva? mentioned above (p. 200). The tentilla are similar to those
of Halistemma and Forskalia, with a naked spiral cnidoband. Athoria larvalis
(PI. XXI. figs. 5-8) was observed living by me in Ceylon. A similar species, but
larger, with more numerous and slender bracts, was found in a mounting of the Challenger
collection (from Station 288, South Pacific). It was not well enough preserved to lie
described and figured.

1 Athoria, name of an Oceanid, 'Mu^ia.
(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 26

•202 THE VOYAGE OF H.M.S. CHALLENGER.

Athoria larvalis, n. sp. (PI. XXI. figs. 5-8).

Habitat. — Indian Ocean; Belligemma, Ceylon, December 1881 (Haeckel).

Nectosome. — The swimming apparatus is composed of an apical pneumatopbore and
a corona of fifteen to twenty large bracts ; these are attached by the pointed end of a
pyramidal pedicle to the axial trunk, immediately below the base of the float. They are
raised and lowered by special muscles in the same manner as in the similar Antho-
physidae. The thick bracts are therefore not only protective but also paddling organs,
as in Athorybia. The diameter of the entire nectosome is 5 to 6 mm.

Pneuviatophorc (figs. 5, 6, p). — The apical float is of medium size, pyriform. with
rounded top and dilated basal part. The latter is divided by a horizontal annular
constriction (or pneumatic pylorus) into an upper and a lower cavity ; the greenish
epithelium of the latter is the pneumadenia. A chitinous pneumatocyst (fig. 6, pf) was
recognisable in the upper part. The pericystal cavity of the pneumatopbore (pc) is
simple, without radial septa ; similar to that of the Apolemidae.

Bracts (figs. 5, 6, b). — The large hydrophyllia are five-sided, prismatic, with five
prominent convex edges, about three times as long as thick. An odd superior or dorsal
edge, and the two parallel dorso-lateral edges are elegantly denticulate, whilst the two
inferior or ventro-lateral edges are smooth. The ventral or axial face between the last
is concave. The proximal fourth of the bract is a five-sided irregular pyramid and its
apex prolonged into the short pedicle, which attaches the hydrophyllium to the trunk.
The distal third is obliquely truncated and contains a small hemispherical or campanulate
cavity (fig. 6, bs). This is the rudimentary subumbrella, the muscular nectosac of which
is preserved. The simple bracteal canal (be) which enters by the pedicle, runs along the
middle line of the concave ventral face and touches the top of the subumbrella ; four very
small radial canals (cr) seem to arise from it, run along the nectosac towards its small
distal ostium, and are there connected by a small ring-canal. The four equidistant points,
where they open into the ring, are armed with a small cnidonode (k), which is composed
of four cnidocysts (rudiments of lost tentacles ?).

Siphosome. — The inferior part of the corm, beyond the superior corona of bracts, is
composed of a large central siphon and a corona of palpons which surrounds its proximal
base. From this arises a long tentacle, beset with a series of tentilla. Each palpon bears
at its base a simple palpacle. A pair of gonostyles is attached on each side of the trunk
of the siphonal pedicle, between the palpons and the basigaster. The male gonophore
lies on the left and the female on the right side of the siphon, whilst the insertion of the
tentacle occupies the middle of the dorsal side of its base, and a small group of buds
fcbe middle line of its ventral side. The frontal section in fig. 6, which exhibits these
topographic relations, is semi-diagrammatic.

REPORT ON THE SIPHONOPHOR^E. 203

Siphon (figs. 5, 6, s). — The large central polypite which represents the axial trunk of
the monogastric corm is composed of four distinct segments. The first and uppermost
segment, which corresponds to the pedicle of the siphons in the polygastric Siphonanthse,
is a vertical spindle-shaped tube which passes over above into the pneumatophore, below
into the basigaster. From this basal segment (at) arise three coronas of lateral appendages,
the upper corona of bracts (b), the middle corona of palpons (q), and the lower corona of
gonophores '(/, h). The second portion of the siphon is a pyriform basigaster (sb), the thick
exoderm wall of which is filled with cnidocysts. The third and largest segment (sm) is
the wide cylindrical or spindle-shaped stomach ; its thickened entoderm bears numerous
conical glandular villi, which usually contain one or two glossy, strongly refracting
globules (vacuoles ?). The fourth and last segment is the distal proboscis (sr), a very
contractile and muscular cylindrical tube which opens through the distal mouth ; this
may be expanded in the form of a broad tabulate suctorial disc (ss).

Tentacle (figs. 5, 6, t). — The single capturing filament, which arises from the base of the
siphon on its dorsal side, is a long cylindrical tube and bears a series of very numerous
tentilla. These are, composed of three parts, a slender proximal pedicle (fig. 8, ts), a broader
cnidoband in the middle (tk), and a simple thin terminal filament (tf). The cnidoband is
naked, without involucrum (as in Rhodophysa, ForsJcalia, and Halistemma) ; it is a
simple spiral, like a cork-screw, with four or five turns.

Palpons (fig. 6, q) and Palpacles (r). — The palpons are attached to the axial trunk
immediately below the bracts and seem to correspond in number to the latter (fifteen to
twenty). They may perhaps be regarded as the dislocated manubria of the medusomes,
the transformed umbrellas of which are the bracts. Each palpon is a very retractile
cylindrical tube, tapering towards the two ends. The open proximal end is attached by
a short pedicle to the trunk and communicates with its cavity ; the closed distal end is
pointed and armed with a bunch of cnidocysts, and coloured with bright-red pigment-
spots. From the pedicle arises on its upper or dorsal side the palpacle, a long, thin,
simple filament, beset with small cnidocysts (fig. 6, r).

Gonodendra. — Below the corona of palpons, between it and the basigaster (sb), is
attached to the trunk an annular group of small buds. These seem to develop into
gonophores ; but only two small gonodendra were developed in the specimen figured,
a male and a female. These were so disposed symmetrically, that the female gonophore
(fig. 6,/) occupied the right side, and the male gonophore (h) the left side of the basi-
gaster. The clustered gonophores were small and very numerous, with a well-developed
umbrella, four radial canals, and a ring-canal. The female manubrium is subspherical
and contains a single large ovum ; the male manubrium is club-shaped and the central
spadix surrounded by ripe sperm.

204 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 38. Athoralia,1 Haeckel, 1888.

Athoralia, Hkl., System der Siphonophoren, p. 39.

Definition. — Athoridae without a nectosac at the distal end of the bracts. Tentilla
with an involucre around the spiral cnidoband. Corms dioecious.

The genus Athoralia differs from the preceding similar Athoria in three characters.
The rudimentary nectosac, which occupies the distal end of the bracts in the latter, is
wanting in the former ; the corms are dioecious ; and the cnidoband of the tentilla is not
naked, but enveloped by an involucrum. Athoralia, therefore, has a relation to Athoria
similar to that which Athorybia exhibits to Rhodoj)hysa. A single species only,
Athoralia coronula, was observed by me, in December 1881, during my residence in
Ceylon. It was very similar to a small young Athorybia, but possessed a single siphon
only, with a single tentacle. Three specimens of it were captured, one male and two
females. The former possessed a single small gonodendron, composed of about a dozen
club-shaped spermaria, besides a number of young buds. Each of the two females had
also only a single gonodendron, composed of numerous clustered, very small gynophores,
each containing a single ovum. Athoralia coronula is therefore one of the rare dioecious
Physonectee, like Apolemia.

■
Family XII. ApoLEMiDii, Huxley, 1859.

Apulemidm, Huxley, Oeeanic Hydrozoa, pp. 70, 127.

Definition. — Physonectse polygastricae, with a long tubular stem of the siphosome,
bearing numerous siphons, palpons, and bracts, each siphon provided with a simple
unbranched tentacle. Nectosome biserial, with two opposite nectophores or two alternate
series of opposite nectophores. Pneumatophore without radial pouches.

The family Apolernidse, founded by Huxley upon the single genus Apolemia, com-
prises those Physonecta? which possess a biserial nectosome and a long tubular stem of
the siphosome, similar to the Agalmidse. They differ, however, from these latter in two
important points. The pneumatophore is a simple glandular invagination of the top of
the trunk, whilst in the Agalmidse the pericystic cavity is divided by vertical septa into
radial pouches. Further, the tentacles in the former are simple, not branched filaments,
whilst in the latter they bear a series of lateral branches or tentilla, each provided with
a cnidobattery.

The first Siphonophore belonging to this family was observed in the North Atlantic
by Lesueur, who in 1813 executed a large and excellent picture of it, drawn and
engraved by himself from life. He called it Stcphanomia uvifiormis (not uvaria).
Eschscholtz observed the same animal in the North Atlantic, and recognising it in the

' Athoralia, derived from Athoria.

REPORT ON THE SIPHONOPHORvE. 205

unpublished plate of Lesueur, founded upon it a new genus, Apolemia uvaria (1829, 1,
p. 143). Blainville copied in 1834 a part of Lesueur's splendid figures in his Actinologie
(24, pi. iii. fig. 1), and Lesson copied the description of it and named it "Apolemia
Lesueuria" (3, p. 518). I myself obtained in 1878 at Paris, owing to the kindness of
Professor Perrier, a copy of Lesueur's beautiful plate, and on comparing it with the
Mediterranean Apolemia uvaria, was convinced that these two forms are not identical,
as preceding observers had supposed, but belong to different species or even genera.

The Mediterranean Apolemia uvaria, the largest Physonect of this sea, was described
in the years 1853 to 1863 by Kblliker (4), Vogt (6), Gegenbaur (7), Leuckart (8), and
Claus (35). The descriptions of these authors together give a satisfactory idea of this
interesting type of the family. It differs from the Apolemia lesueuria in the dioecious
conn and the naked internodes of the siphosome, which in the latter are densely covered
with innumerable bracts. Since the corms, too, in this latter are monoecious, I separate
it as Apolemopsis lesueuria.

Closely related to this latter seems to be an Apolemid from the Tropical Pacific, which
Mertens observed near the Caroline Islands, and Brandt described in 1835 under the
name Apolemopsis dubia (25, p. 36). Comparing the accurate figure of it, which
Mertens had drawn from life, with the plate of Lesueur, I think these two forms belong
to the same genus, but are distinct species.

During my voyage through the Indian Ocean, from Aden to Bombay, in 1881, I
captured a single but complete specimen of the interesting new Physonect, which is
figured in PI. XVIII. figs. 1-7, of this Report, under the name Dicymba diphyopsis.
The composition of the corm and the form of the single organs are almost as in the well-
known Mediterranean Apolemia uvaria ; but there are two important differences ; the
nectosome is composed of two opposite nectophores only (as in Pray a and Diphyes), and
the cormidia are monogastric, with a single siphon and tentacle (as in the Diphyidae and
Agalmidse). This Indian Physonect may therefore be regarded as the type of a new
subfamily, or even famdy — Dicynibidse.

Nectosome. — The swimming apparatus of the Apolemid* is similar to that of the
Agalmidse, but differs from it in two characteristic peculiarities. The pneumatophore is a
simple invagination of the exoderm, without radial pouches ; and the nectophores
beyond it are provided with tentacles wanting in the Agalniidse. The number of
nectophores is different in the two subfamilies ; Dicymba, the single knowrn type of the
subfamily Dicymbidse, possesses only two large opposite nectophores, similar to Praya
and Diphyes, and approaches in this as well as in other respects to the Diphyidae. The
subfamdy Apolemopsidae, represented by Apolemia and Apolemopsis, on the other hand,
has two obliquely opposite series of alternating nectophores (four to six pairs or
more), similar to the Polyphyidse and Agalmidae. The long and thin contractile filaments
which arise from the trunk of the nectosome between the single nectophores are

206 THE VOYAGE OF H.M.S. CHALLENGER.

generally described as " tasters." It may, however, be possible, that they are originally
not palpons, but palpacles. In this case their morphological value would be different, as
is now assumed. They would be the dislocated tentacles, and not the manubrium of the
metamorphosed medusome, the umbrella of which is the nectophore. A proof of this
explanation seems to be given by the fact, that in Apolemopsis (according to the
accurate figure of Lesueur) a bunch of four tasting filaments arises from the base of each
nectophore. Kolliker (4, p. 19) and Leuckart (8, p. 317) state, that in Apolemia also
a bunch of three or four tasters belongs to each single nectophore.

Pneumatophore. — The float filled with air is relatively small in the Apolemidge,
compared with the large nectophores. It has a very simple structure, as in the oldest
and lowest forms of Physonectse. The ovate pneumatosaccus (which sometimes
contains no pneumatocyst V) is a simple invagination of the apex of the tubular trunk.
The inflated pyriform uppermost part of the latter, or the pneumatocodon, which
loosely surrounds the pneumatosac, is not connected with it by vertical radial septa (as
is constantly the case in the Agalmida? and Forskalidae). There is wanting, therefore, in
the Apolemidse the corona of radial pouches which is characteristic of the pneumatophore
in the two latter families. The spheroidal basal or lowermost part of the pneumatosac
— the pneumatic infundibulum, or the gas-secreting gland, pneumadenia — is separated
from its ovate larger upper part by an incomplete annular constriction, the pneumato-
pyle (pylorus infundibuli). (Compare 50, p. 272, Taf. xix. fig. 93.)

Nectophores. — The large and vigorous nectocalyces of the Apolemidse have a some-
what different shape in the two subfamilies. The two opposite nectophores of Dicymbu
(PI. XVIII. fig. 1) resemble those of Praya (PI. XXXI. figs. 1-7). They are ovate,
with a rounded and edgeless exumbrella, and bear at the ventral or axial side a large
longitudinal furrow, bounded by two parallel wings ; between these wings there arises
in the upper part the lamellar triangular pedicle, which attaches the nectophores to the
top of the stem, beyond the pneumatophore. The two ventral grooves of the two
opposite nectophores, the larger of which embraces the smaller, form together a
hydrcecial canal, in which the siphosome may be partly retracted. Apolemia bears to
Hippopodms much the same relation as Dicymba exhibits to Praya. The large ventral
groove of each nectophore here embraces a corresponding part of two obliquely opposite
nectophores, a superior and an inferior (compare 8, p. 314). The form of the umbrella
is similar to that of Hippopodius, and so also is the arrangement in the biserial
nectosome. The mouth of the nectosome is relatively small, and directed downwards
and outwards. The four radial vessels of the powerful subumbrella, connected by a
small ring-vessel above the insertion of the velum, are strongly differentiated. The two
sagittal canals (shorter ventral and longer dorsal) make a simple curve in the median
plane of the nectophore, whereas the two lateral canals (right and left) are much
prolonged and have a complicated course, with two to four undulate turnings ; from the

REPORT ON THE SLPHONOPHOR^E. 207

uppermost turning often arises a series of short diverticula or villiform lateral branches
(compare 4, p. 18, Taf. vi. figs. 6-9, and 8, p. 315, Taf. xii. fig. 7).

Siphosome. — The tubular trunk beyond the nectosome in all Apolemidaa is very
long, and attains in the extended state a length of two or three feet or more. It bears
a great number of ordinate cormidia, separated by long internodes of equal length.
These are naked in Dicymba and Apolemia (similar to those in the polygastric Caly-
conectse), whilst they are densely covered with innumerable bracts in Apolemopsis
(as in Agalmopsis). The trunk is much shortened in the highly contracted state ;
the internodes then nearly disappear and the entire corm is covered by a carapace of
scales, the densely crowded bracts.

Cormidia. — The two subfamilies of Apoleruidse are similar in the general conforma-
tion of the cormidia, and the structure of their single parts ; they exhibit, however,
an important difference in their composition. Each cormidium of the Dicymbidaa has
only a single siphon and a single cyston, surrounded by numerous bracts and palpons ;
whereas in the Apolemopsidse each cormidium possesses several (two to four or more)
siphons, and the same number of cystons. The Dicyinbidse, therefore, have monogastric
cormidia (like the Rhizophysidse, Pis. XXIII., XXIV.), whilst the Apolemopsidse
possess polygastric cormidia (like the Salacidse, PI. XXV.). The number of bracts
(usually twenty to forty in each cormidium) seems to be in all Apolemidse about the
same as the number of palpons and palpacles, so that perhaps each bract, together with
an appertaining palpon and a single palpacle, represents originally a medusome, the
organs of which are modified and dislocated ; the bract corresponding to the umbrella,
the palpon to the manubrium, and the palpacle to the single tentacle.

Bracts. — The hydrophyllia, as the metamorphosed umbrella? of the medusomes,
exhibit in all Apolemidse hitherto observed the same peculiar form. They are ovate,
club-shaped or pyriform, with rounded distal end and pointed proximal end ; the latter
is attached to the stem by a short pedicle, which is raised or lowered by a muscle. The
convex outside (exumbrella) is armed with numerous whitish patches composed of cnido-
cysts, whilst the concave inside (subumbrella) is smooth. Near the latter there runs in
the median line of the bract a simple bracteal canal, which arises from the axial canal
of the trunk and ends blindly towards the distal end ; sometimes it is provided, near
the latter, with a small cEecal diverticulum directed towards the lower face (compare
7, p. 320, Taf. xviii. figs. 1-3, and 8, p. 316, Taf. xii. fig. 8).

Sipthons. — -The feeding polypites have in all Apolemidae the same structure ; the single
siphon in the monogastric cormidia of Dicymba (PI. XVIII. figs. 1, 2, s), however, is
relatively larger, whilst the several siphons (two to four or more) in the polygastric cormidia
of Apolemia are smaller, and are more like the palpons. The four segments of the
siphon (PI. XVIII. fig. 2, s) are usually distinct, and already very well represented in
the oldest figure, given by Lesueur. The short pedicle, to which is attached the single

•

208 THE VOYAGE OF H.M.S. CHALLENGEE.

long tentacle (t), bears a hemispherical basigaster with a thick exodermal wall full
of cnidocysts (*/>). The large ovate or fusiform stomach (s) possesses four or six
strong hepatic ridges (sh), composed of small villi and coloured red or brown (four in
Dicymba and Apolemopsis, six in Apolemia). The long tubular proboscis (sr) bears a
corresponding number (four or six) of longitudinal muscle-bands, and at the distal mouth
a similar number of small rounded lobes.

Tentacles and Palpacles. — All Apolemidse bear very numerous long and thin fila-
ments, which are usually described as tentacles. According, however, to the general
definition, which holds good for other Siphonophorse, we may call only those larger
filaments which are attached (singly) to the base of the siphons tentacles, whilst we
call the similar smaller filaments which arise from the base of the cystous and palpons
palpacles (thus a single one from each polypite). The structure is otherwise the same
in both. They are simple, thin and long cylindrical tubules, closed at the distal end,
opening into the pedicle of the polypite at the proximal end ; they never bear lateral
branches. The structure of the cylindrical wall is the usual one, a vibratile entodermal
epithelium inside, a cnidal exodermal epithelium outside, and between them an elastic
fulcrum, which bears inside a thin plate of ring-muscles, and outside numerous radial
ribs covered with longitudinal muscles. The cnidocysts are larger and more numerous
in the abaxial part of the exoderm and towards the distal end, often arranged in two or
four longitudinal series.

Cystous. — Each siphon or feeding polypite of the Apolemidse is associated with a cyston
or excreting polypite (fig. 2, y). The Dicymbidse, therefore, have in each monogastric
cormidium a single cyston, the Apolemopsidee in each polygastric cormidium several
cystons, two to four or more. The cystous or " anal vesicles " are intermediate in size
between the larger siphons and the smaller palpons, and at once distinguished from both
by the dark (red or brown) colour of their nontransparent body. Their four segments
are usually not so distinct as in the similar but more fully developed siphons ; the
hepatic ridges of the latter are replaced by series of glandular villi, secreting a granular
red or brown pigment-mass. This is accumulated in a vesicular terminal diverticulum
of the proboscis, and may be ejected through a small opening of the latter (anus).

Palpons. — The Apolemidae possess exceedingly numerous tasters or palpons, usually
twenty to forty or more in each single cormidium, therefore several thousands, when
the number of cormidia exceeds a hundred, as is often the case in corms of two or
three metres in length. The palpons are slender, very mobile, cylindrical or spindle-shaped
tubes, closed at the pointed distal end, which is richly armed with cnidocysts and long
cnidocils. The middle part of the utricle exhibits sometimes four or six longitudinal
ridges, corresponding to the hepatic stripes of the siphons and the excretory pigment-
stripes of the cystons. The pedicle of each palpon bears a long, very thin palpacle,
similar to that of the cyston (compare 7, pi. xviii. fig. 4, and 8, Taf. xii. p. 10).

REPORT ON THE SIPHONOPHORiE.

209

Gonophores. — The rnedusiform gonophores arise in clusters from branched gono-
styles, and possess in both sexes of the Apolemiche a well-developed umbrella with four
radial canals and a connecting ring-canal ; Dicymba (PI. XVIII. figs. 4, 6) is besides
distinguished by the possession of four rudimentary tentacles which are placed at the
distal end of the radial canals and bear a red ocellus (as in Desmopliyes and Lilyopsis).
The ovarium (or the manubrium of the female Medusa) includes a single large ovule
surrounded by an irregular network of spadicine canals (figs. 3, 4). The spermarium (or
the manubrium of the male Medusa) is a large club-shaped sac with a central spadix
(figs. 5, 6). The corms of Apolemia are dioecious and bear in each cormidium a single
gonodendron, all of the same sex in one corm. The corms of Apolemopsis and Dicymba
are monoecious and bear in each cormidium two gonodendra, a male and a female ; they
arise separately from the common trunk on the base of the cormidium.

Synopsis of the Genera of Apolemidse.

I. Subfamily Dictmbidje.

Nectosome with two opposite neoto-
phores only. Cormidia monogastric,
each with a single siphon and cyston.

II. Subfamily Apolemopsim;.

Nectosome with two opposite rows of
nectophores. Cormidia polygastric,
each with several siphons and eystons.

Internodes of the siphosome naked. Corms
moncecious. Cormidia monoclinic, with
two gonochoristic gonodendra (a male and
a female), ...... 39. Dicymba.

' Internodes of the siphosome naked. Corms
dioecious. Cormidia diclinic, with a
single gonodendron (either male or female), 40a. Apolemia.

Internodes of the siphosome covered with
bracts. Corms monoecious. Cormidiamono-
clinic, with two gonochoristic gonodendra, 40?;. Apolemopsis.

Genus 39. Dicymba,1 Haeckel, 1888.

Dicymba, Hkl., System der Siphonophoren, p. 39.

Definition. — Apoleroidse with two large opposite nectophores only. Internodes of the
siphosome naked. Cormidia monogastric and monoclinic, each with a single siphon and
cyston, and with two separate gonodendra, a male and a female. Corms moncecious.

The genus Dicymba is represented by a new interesting Apolemid, which I
observed living during my voyage through the Indian Ocean, from Aden to Bombay, in
November 1881. The special organisation of the single parts which compose the
polygastric corm, is similar to that of the common Apolemia ; but their disposition and
number are different. The nectosome of Dicymba is composed of two large opposite
nectophores only (as in Praya and Dipliyes). The cormidia, which are separated by long
free internodes, are monogastric, each provided with a single siphon and a single cyston
only, besides numerous palpons. The rnedusiform structure of the gonophores is also
peculiar. These differences seem to be so important, that Dicymba might be separated
from the true Apolemidae as the representative type of a new family Dicymbidse.

(ZOOL, CIIALL. EXP."

1 T)icymhri = Double boat, nixvpfia.
-PART I.XXVTI. — 1888.)

Ilhbli 27

210 THE VOYAGE OF H.M.S. CHALLENGER.

Dicymba diphyopsis, n. sp. (PL XVIII. figs. 1-7).

Habitat. — Indian Ocean, between Aden and Bombay, November 1881 (Haeckel).

Nectosome (fig. 1). — The swimming apparatus is composed of a small pneumatopbore
placed at the top of the stem, and of two large opposite nectophores beyond it. These
are slightly different in size, and rather similar to the nectocalyces of Praya (PI. XXXI.)
in form, structure, and arrangement, so fitting one into another, that the two longitudinal
ventral wings of the larger embrace the opposite wings of the smaller swimming-bell.
The subcylindrical hydrcecial canal, formed by the two longitudinal ventral grooves, is
traversed by the apical part of the trunk, and embraces a great part of the retracted
siphosome. This attains in the fully expanded state a length of about half a metre.

Pneamatophore. — The float is a pyriform vesicle of 10 mm. in length and 6 mm. in
breadth. Its apical part is covered with red pigment (fig. l,p). The pneumatosac is a
simple invagination of the exoderm of the stem-top, and not connected with the sur-
rounding pneumatocodon by radial septa (compare above, p. 206).

Nectophores. — The two opposite nectophores are of equal form, but a little different
in size, 40 mm. to 50 mm. long, 25 mm. to 30 mm. broad. Their form is ovate, with
rounded apex and truncate base. The dorsal or abaxial side is evenly convex, without
edges, but with a number of flat roundish tubercles, which bear white patches composed
of cnidocysts. The ventral or axial side is concave, with a broad longitudinal groove
bounded by two prominent lateral wings. In the upper third of the groove, midway
between the two wings, arises a short, obliquely triangular lamella, the pedicle of the
nectophore. The apex of this triangular pedicle is inserted near the apex of the trunk,
somewhat below the base of the pneumatophore. The larger nectophore embraces by its
ventral groove the opposite groove of the smaller in the same way as is described above
in the case of Praya galea (PI. XXXI. figs. 1-7 .

Nectosac. — The umbrellar cavity occupies about two-thirds of the nectophore, and is
subspherical in the larger proximal half, subcylindrical in the smaller distal half. The
opening of the latter is surrounded by a broad velum (fig. 1, v). The muscle-plate of the
subumbrella is strong. The nectocalycinc duct arising near the top of the stem, passes
downwards through the pedicle of the nectophore and ends in the upper third of the
dorsal median line of the subumbrella. It divides here into four radial canals of very
different lengths ; the ventral is about half as long as the dorsal, and both are shorter
than the two paired lateral canals (right and left) ; these are four times curved in different
directions and form the four loops figured in fig. 1, n. All four canals inosculate in the
circular canal of the umbrella margin at equal distances.

Siphosome. — The long and thin tubular trunk of the siphosome had in the single
specimen observed, in the fully expanded state, a length of 40 to 60 cm. It bore (besides

REPORT ON THE SIPHONOPHORiE. 211

a number of buds in the uppermost part, beyond the nectophores) a series of a dozen
fully-developed cormidia. The internodes of the trunk between these were naked, and
had a length of 4 to 5 cm. In the contracted state the trunk was so shortened that the
naked internodes disappeared, and the cormidia formed a continuous clustered mass ;
the upper part of this was hidden in the space between the ventral grooves of the two
nectophores, comparable to a hydrcecium.

Cormidia (fig. 2). — Bach cormidium is composed of a single siphon with its
tentacle ; a single cyston with a palpacle ; a bunch of palpons, each with a palpacle
(ten to twenty); a clustered mass of club-shaped bracts (fifteen to twenty -five); and a
pair of clustered gonodendra, a male and a female. We may suppose that each bract
is the reduced umbrella of a medusome, the manubrium of which is either a siphon, or
a cyston, or a palpon : each one is provided with a tentacle or a palpacle. In this case
the number of sterile medusomes in each cormidium would be fifteen to twenty-five.
The number of sexual medusomes is much larger since the male as well as the female
gonodendron is composed of twenty to thirty or more clustered gonophores.

Bracts (fig. 2, h). — The hydrophyllia, fifteen to twenty-five in each cormidium
(besides numerous small buds of young bracts), form together a clustered mass which
covers and protects the dorsal or superior side of each cormidium. The form and
structure of the bracts are nearly the same as in the common Apolemia. They are
club-shaped or pyriform bodies 15 to 25 mm. in length and 10 to 15 mm. in breadth,
rounded at the thickened distal end, pointed at the basal end, where they are attached
to the trunk by a short mobile pedicle. Their convex outer face is covered with white
patches composed of cnidocysts. Near the concave inner face there runs along the
median line a simple bracteal canal, which ends blindly near the distal end.

Siphons (figs. 1, 2, s). — The single siphon, which represents the only feeding person
of each cormidium, is rather large, in the expanded state 20 to 30 mm. long and 4 to
8 mm. thick. It has a yellowish colour, and exhibits the usual four segments distinctly ;
a slender pedicle, to which the tentacle is attached ; a pyriform thick -walled basigaster
(sb), the exoderm of which contains masses of thread-cells ; an ovate or spindle-shaped
stomach, distinguished by four strong undulate liver-ridges of a red-brown colour (sh),
and a muscular proboscis, in the expanded, very contractde wall of which four longi-
tudinal muscle-bands can be distinguished (sr). The distal mouth opening may be
expanded in form of a broad suctorial disc, which is sometimes circular, at other times
provided with four or eight slight mouth lobes.

Tentacles (figs. 1, 2, t) and Palpacles (figs. 1, 2, >•). — The single tentacle which is
attached to the base of each siphon, is a long, simple, cylindrical filament, beset with
two longitudinal rows of cnidocysts. It has nearly the same structure as the similar
palpacles attached to the cystons and palpons ; these, however, are smaller, much
thinner, and less developed (compare above, p. 208).

212 THE VOYAGE OF H.M.S. CHALLENGED

Cystous (figs. 1, 2, (/). — Each cormidium possesses a single cyston or anal vesicle,
attached to the trunk near the base of the siphon. It is smaller than the siphon, but
larger than the palpons, and at once distinguished from both by its deep red colour.
The cyston is a slender spindle-shaped tube with two slight constrictions and a middle
dilatation. This corresponds to the stomach of the siphon, and is densely covered
internally with red glandular villi. The granular pigment secreted by these is accumu-
lated in a head-like terminal expansion of the distal proboscis, and thrown out by a small
terminal opening, the anus. The slender basal pedicle of the cyston bears a simple
palpacle, of the same shape as that of the palpon.

Patyons (figs. 1, 2, ). — The tasters occur in each cormidium nearly in the same
number as the bracts, ten to twenty or more, besides numerous small buds of young
ones. They are slender cylindrical or spindle-shaped tubules, very extensile and con-
tractile, and as in Apolemia have a restless dashing motion. The closed distal end of
each palpon is pointed and richly armed with cnidocysts and palpocils. The thinner
and pediculate basal end opens into the axial canal of the trunk, and bears a long and
thin palpacle (r), sinrdar to that of the cyston.

Gonodendra. — Each cormidium is hermaphrodite (monocliuic) and bears two
clustered gonodendra, a male and a female ; they arise separately from the trunk, both
near the base of the cyston. The female gonodendron (fig. 3) is composed of twenty to
thirty gynophores, besides numerous small buds. The male gonodendron (fig. 5) is
smaller and bears only fifteen to twenty androphores. The umbrella of the gonophores
is in both sexes well developed, with four radial canals, and a circular ring-canal on the
margin ; the latter bears, at the distal end of the four radial canals, four small tubercles
with a red pigment-spot, which are rudiments of reduced tentacles, with a basal ocellus.
The gynophores (fig. 4) have a campanulate umbrella and a colourless subspherical
manubrium, which contains a single large ovulum, surrounded by spadicine canals. The
androphores (fig. 6) have a more oblong umbrella and a club-shaped manubrium of a
bright red colour ; its central spadix is surrounded by a thick layer of sperm.

Genus 40a. Apolemia,1 Eschscholtz, 1829.
Apolemia, Esch., System der Acalephen, p. 143.

Definition. — Apoleinidse with a biserial nectosome, composed of two opposite series
of nectophores. Internodes of the siphosome naked. Cormidia polygastric and diclinic,
each with several siphons and cystons, and with a single gonodendron, either male or
female. Corms dioecious.

The genus Apolemia was established by Eschscholtz for that North Atlantic form
which Lcsueur had figured in 1813 under the name Stephanomia uviformis (not

1 Apolemiii = Pacific, as-oAs^oj.

REPORT ON THE SIPHONOPHOR^E. 213

uvaria .'). Kolliker (4) aud the following observers, who described in the years 1853
to 1863 the Mediterranean Apolemia uvaria (called Agalma punctata by Vogt, 6),
supposed that these two species were identical. But a comparison of both has convinced
me that they belong to different genera. The internodes of the long tubular siphosome
are naked in the Mediterranean Apolemia uvaria, whilst they are densely covered with
bracts in the North Atlantic Apolemopsis uviformis (or Apolemia lesueuria) ; the corms are
dioecious in the former, monoecious in the latter. I retain, therefore, the name Apolemia
uvaria, now generally accepted for the Mediterranean form, for this type of the genus,
the gigantic corm of which attains a length of two or three metres and more. Compare
the descriptions of the corm by Vogt (6), Gegenbaur (7), and Leuckart (8), of the necto-
phores by Kolliker (4), and of the gonophores by Claus (35).

Genus 406. Apolemopsis,1 Brandt, 1835.

Apolemupsit, Brandt, Prodromus, 25, p. 36.

Definition. — Apolemidse with a biserial nectosome, composed of two opposite series
of nectophores. Internodes of the siphosome densely covered with bracts. Cormidia
polygastric and monoclinic, each with several siphons and cystous, and with two separate
gonodendra, a male and a female. Corms monoecious.

The genus Apolemopsis was established by Brandt (25) for an Apolemid, which
Mertens had observed in the Tropical Pacific, near the Caroline Islands. Comparing his
accurately drawn figures with the splendid pictures which Lesueur had given in 1813 of
his North Atlantic Stephanomia uviformis, I suppose that these two similar forms may
be distinguished as two species of one genus. This genus, for which I retain Brandt's
name Apolemopsis, seems to differ from the true Apolemia (uvaria) in two essential
characters. The entire siphosome of Apolemopsis is densely covered with innumerable
bracts, as in Agalmopsis, whilst in Apolemia the long internodes between the cormidia
are naked, as in the Diphyidaj. The corms of the former are monoecious, those
of the latter dioecious. Each siphon possesses in Apolemopsis four liver-ridges (as in
Dicymba), in Apolemia six. A further careful comparison, however, of the two
genera, as well as of the different species belonging to them, is necessary by future
observers.

Family XIII. Acalmidj, Brandt, 1835.

Agalmidx, Brandt, Prodromus, &c, 1835, 25, p. 34.
Steplianomidx, Huxley, Oceanic Hydrozoa, 1859, pp. 70, 72.

Definition. — Physonectae polygastricae, with a long tubular stem of the siphosome,
bearing numerous siphons, palpons, and bracts, each siphon provided with a branched

1 Apolemopsis = Similar to Apolemia.

•J 1 4 THE VOYAGE OF H.M.S. CHALLENGER.

tentacle. Ncctosome biserial, with two opposite rows of nectophores. Pneumatophore
with radial pouches (compare Pis. XIV.-XVIL).

The family Agalmidse, the largest of all Physonectse, comprises those polygastric
" Physophoridse " which possess a biserial nectosome, and at its apex a pneumatophore
with radial pouches; the long tubular stem of the siphosome bears numerous siphons,
bracts, and palpons ; the tentacles are always branched, with a single series of tentilla.

The genera and species of Agalmidse are rather numerous, and widely distributed over
all seas ; they occur in the Arctic as well as in the temperate zones, but mostly in the
Tropics. The majority, however, occur only at certain seasons and not in great numbers;
nearly all are extremely delicate and sensitive, and the component parts easily detached
from the stem. Most of the older observers, therefore, have only described fragments
or single isolated pieces. A further great obstacle to accurate examination is the
extraordinary mobility and contractility of most Agalmidse.

The first figures and descriptions of Agalmidse were given by Peron and Lesueur (14,
Stephanomia, 1807), and by Eschscholtz (21, Agalma, 1825). Lesson (3, 22) and Quoy
and Gaimard (2, 19, 20) published figures and descriptions of numerous scattered pieces,
but without great value. Brandt in 1835 described Agalma mertensii from an excellent
(though alas unpublished) figure by Mertens (made in 1827), and founded upon it the
family Agalmidse (25). Sars in 1846 published accurate figures of the northern Agalmopsis
elegans. The excellent observers in the sixth decade of our century (1853-1859),
Kolliker (4), Vogt (6), Leuckart (5, 8), Gegenbaur (7, 10), and Huxley (9), greatly advanced
our knowledge of the Agalmidse, which were also called Stepbanomidse (including
Forskalia). Some new interesting species have been described recently by Claus (74,
75), Fewkes (42-45), &c. In general, however, there yet remains much to be done towards
a more accurate knowledge of this important and interesting family.

My own observations on numerous different Agalmidse were commenced in 1859 in
Messina, and continued in the winter of 1866-67 in the Canary Islands ; but the richest
harvest was found during my residence in Ceylon, where I had the opportunity of observing
several new and interesting forms. The Challenger collection contained many isolated and
scattered portions of detached parts of Agalmida3, but no complete specimens of any value.

Nectosome. — The swimming apparatus of the Agalmidse is composed of a small apical
pneumatophore and of two opposite rows of large alternating nectophores. These are so
arranged around the axial trunk, that the apical part of each nectophore fits into the
interval between two neighbouring nectophores of the opposite row, a superior and an
inferior. The trunk itself, therefore, is spirally twisted, since the insertions of all the
nectophores originally form a single straight series in the ventral median line of the trunk.
The spiral line usually is lseotropic (or a lambdoid spiral), therefore opposed to the spiral
of the siphosome, which is (perhaps always) dexiotropic (or a deltoid spiral). The number
of nectophores is in most species ten to twenty, but in some smaller forms only four

REPORT ON THE SIPHONOPHORJE. 215

or six, in the largest forty to fifty or more. The pedicles of the nectophores are usually
small, and easily detached from the axial trunk.

Pneumatophore. — The aeriferous float in all Agalmidas is small, often very small in
comparison to the nectophores. It is placed at the top of the trunk, the uppermost part
of which is sometimes prolonged, so as to form a contractile pedicle to the float ; in this
case it is able either to pass forward over the uppermost nectophores, or at other times to
be retracted between them. Usually the float is ovate, spindle-shaped or pyriform. Its
top seems to be closed, without a constant opening; it is often coloured by a small red
or brown pigment-spot, and sometimes this forms a regular octoradial star, the centre of
which is colourless, like an ocellus. The lower half of the pneumatophore often exhibits
a number of equidistant longitudinal ribs, the insertions of the radial vertical septa which
connect the outer with the inner wall, and divide the cavity of the pueumatophore into radial
pouches ; the number is usually eight, sometimes variable (seven or nine), at other times
four, six or twelve ; the upper portion of the septa passes over into the circular muscular
ring, which surrounds the pylorus infundibuli like a sphincter or diaphragm.

Nectophores. — Although the form of the nectocalyces in the numerous Agalmidse is
very manifold, it is always developed from the same original type, and represents only
variations of a single type, which is defined by their alternately pinnate arrangement
on the axial trunk of the biserial nectosome. The quadriradial umbrella of the necto-
phores is always bilateral, with a complete symmetry of both its halves. It is more or
less depressed in the sagittal direction, from the convex dorsal to the concave ventral
side, so that the frontal or transverse axis is longer than the sagittal. The principal
axis is sometimes longer, at other times shorter than the frontal; it is directed towards
the axial trunk more or less obliquely, and intersects it at a variable angle ; but the
apical pole (with the pedicle) is always situated more highly than the basal pole (with
the ostium) ; the narrower ostium is directed outwards and downwards. The pedicle of
the nectophore, which arises in the median line of its lower or ventral side, is a short
triangular lamella ; its proximal apex is inserted on the ventral median line of the axial
trunk. This latter is constantly embraced by a pair of large auricles, apical wings or
frontal horns, which arise from the dilated lateral parts of the nectophore. The sharp
proximal edges of the wedge-shaped horns fit so one over another between the two
opposite nectophores, that the axial part of the nectosome in the lateral view exhibits a
very characteristic zigzag shape.

Nectosac. — The subumbrella occupies sometimes scarcely the distal half of the
nectophore, at other times its greater part. It exhibits constantly the same bilateral
form, with a complete symmetry of both lateral halves, and is depressed in sagittal,
dilated in frontal direction. Usually it is divided into three parts, an odd median part
with the basal ostium, and two paired lateral parts which correspond to the two frontal
horns. The distal ostium is usually small. The four radial canals of the nectosac are

216 THE VOYAGE OF H.M.S. CHALLENGE?,.

always in two very different pairs ; the two opposite sagittal canals (shorter ventral and
longer dorsal) are simply curved in the median plane of the nectosac ; the two paired and
equal lateral canals (right and left) are much longer, and more or less curved in different
directions, usually with three or four roundish loops, the course of which is often
characteristic of the single species. The top of the subumbrella, where the four radial
canals arise from the peduncular canal, is dislocated more or less towards the ventral side.
The points where the four radial canals open into the circular ring-canal, above the
insertion of the small velum, are sometimes marked by four red pigment-spots ; at other
times only two or three ocelli are preserved (an odd dorsal and two paired lateral) ; the
fourth (ventral) has disappeared (PL XVIII. figs. 8, 9).

Siphosome. — The external form and internal structure of the siphosome, as well as
the character of the motions and habits, are so different in the various Agalrnidse,
that we may divide this large family for that reason into two subfamilies : Crystallodinaj
and Anthemodinse (25, pp. 39, 40). The siphosome of the Crystallodinas (Agalma,
Crystallodes, &c.) is relatively short, about as long as or little longer than the nectosome ;
it is very little expansive and contractile, and distinguished by a peculiar rigidity,
caused by the peculiar shape and junction of the bracts ; these are very thick and
firm, prismatic or wedge-shaped, cartilaginous portions, so densely packed one over the
other that the intervals nearly disappear ; they form a complete carapace of scales
around the trunk even in its most expanded state. The motions of the siphosome in
the Crystallodinse, therefore, are very weak and inconsiderable (compare PI. XVII.).

The second form of the siphosome, very different from the first, is represented by
the Anthemodinse. It is very long and movable, usually much longer than the
nectosome, and in the expanded state often many times longer. The tubular trunk of
this siphosome is very extensible and contractile, and in the expanded state only
loosely covered by the bracts ; these are usually thin scales, often foliaceous, and
separated by dilatable intervals. The motions of the siphosome in these Anthemodinse
(Halistemma, Agalmopsis, &c.) are usually very active and quick ; the expanded stem
may be suddenly contracted and then occupy a much smaller space (one-tenth or less
of the expanded corm) (compare Pis. XIV.— XVI.).

Cormidia. — The polymorphous persons and their organs are arranged and grouped
in the siphosome of the Agalrnidse in a very variable order ; generally we may
distinguish ordinate and irregular cormidia ; there are, however, intermediate stages
between these two types. Perhaps the whole famdy may be divided according to this
difference into two subfamilies — Stephanomidse (with ordinate cormidia) and Halistem-
midse (with irregular cormidia) ; in both subfamilies occur Crystallodinse (with rigid
siphosome) and Anthemodinse (with movable siphosome). The ordinate cormidia of
the Stephanomidse are equidistant and separated by internodes of equal length, which
are only covered with bracts. They exhibit a most primitive and simple arrangement

REPORT ON THE SIPHONOPHOR^E. 217

iii Stephanomia and Crystattodes, where they form a single rectilinear series in the
ventral median line of the rigid trunk ; all parts of the cormidia here hang down from
its ventral or inferior side, whilst the dorsal or superior side is only covered with bracts
(PI. XVII. fig. 1). Antliemodes and Cuneolaria differ from the former in the spiral
twisting of the prolonged and very movable stem ; the cormidia, therefore, are turned
in all directions; but they are also separated by long internodes which are only covered
with bracts (PI. XIV.). Each cormidium is composed in these four genera of a single
siphon with its tentacle ; one or more palpons (or cystons), usually each with a palpacle ;
a group of bracts, and a monoclinic pair of distylic gonodendra (a male and a female)
(PI. XV. fig. 5,/, h ; PL XVII. fig. 4,/, h).

The Halisternmidse — or the Agalmidaa with dissolved cormidia — comprise the
majority of this family, viz., all the genera except the four above mentioned. The poly-
morphous persons and their organs are here more or less dislocated and scattered ; the
palpons and gonostyles arise (singly or united in groups) directly from the trunk of the
siphosome, not from the base of the siphons as in the Stephanomidse. Usually also
here the internodes between the siphons are of equal length ; they are, however, not
free, but covered with palpons, cystons, and gonodendra variously arranged : some-
times rather regularly (as in Phyllophysa, Cupulita, &c.) ; at other times very
irregularly (as in Halistemrna, Agalmopsis, &c). A peculiar structure already described
by Eschscholtz (1, p. 150) is developed in Agalma, where the bracts compose a scale, a
carapace with a central cavity, or an axial hydrcecium into which the distal part of the
siphosome may be retracted (PI. XVIII. fig. 8).

Bracts. — The hydrophyllia or " covering scales " in all Agalmidse are very
numerous, often several hundreds, in the largest forms more than a thousand. They
arise usually not only from the nodes of the trunk, where the siphons are attached, but
also from the internodes between them. The carapace of scales, which is composed of
the jointed bracts apposed one to another, is always complete in the contracted state of
the siphosome, and often also in the expanded state. Their special form and arrange-
ment are very different in the various Agalmidse. Generally the bracts are thick,
prismatic or wedge-shaped in the Crystallodinse, where they cover the rigid trunk
so densely that their intervals nearly disappear and the siphosome loses its contrac-
tility. In the Anthemodinae, on the other hand, where the stem is very extensile
and contractile, the bracts are usually thin, foliaceous or squamous, and the intervals
between them of very variable size. The general form of the bracts is sometimes
ovate, lanceolate, or rhombic, at other times trigonal, tetragonal, or pentagonal, often
with three to five (rarely more) prominent teeth at the distal margin. Usually the
superior or outer face is more or less convex (often with prominent ribs, armed with
cnidocysts), the inferior or inner face concave ; near this runs in the median line of the
bract the simple blind bracteal canal. The clear and hyaline jelly-substance of the

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 28

•J IS THE VOYAGE OF H.M.S. CHALLENGER.

colourless bracts is usually more or less cartilaginous, sometimes soft ; it is thickened
in the middle part and often towards the distal edge. The proximal base tapers
towards the small movable pedicle, which attaches the bract to the trunk.

Siphons. — Each cormidium of the Agalmidse possesses a single siphon only, and
this is placed originally always (and in the ordinate cormidia permanently) at its distal
or lower end. The four segments of the siphon exhibit a varying degree of develop-
ment. The pedicle (sp) is usually short, but sometimes prolonged (e.g., in Lychnagalma).
The basigaster (sb) is usually small, sometimes rudimentary. The stomach (sm) in most
Agalmidse is large and provided with longitudinal equidistant liver-ridges, usually of
a red or brown colour. Their number in most Agalniida? is eight, sometimes four
(Anthemodes, PI. XV. fig. 7), twelve (Cuneolaria), or sixteen (Halistemma, 6, pi. viii.
fig. 1). Usually the hepatic ridges are continuous glandular bands, but sometimes
composed of single villi arranged in longitudinal series. The proboscis (sr) is always
a very muscular cyHndrical tube, highly expansible. Its distal mouth is extremety
variable inform and size; it may be expanded in the form of a very large and thin-
walled suctorial disc, sometimes circular, at other times polygonal (often octagonal).
Its edge is usually armed with cnidocysts.

Tentacles. — The single long tentacle, which is attached to the base of each siphon,
exhibits the same essential structure in all Agalmidae, but shows great variety in the
form of its equidistant lateral branches. The various forms of these tentilla have been
already employed by Eschscholtz (1829) and afterwards by Huxley (1859) for the
distinction of genera. The simplest and most primitive form is found in Halistemma ;
the cnidoband is a simple, thickened, spirally convoluted dilatation of the middle
part of the tentillum, with a double elastic band (or angle-band) on its ventral side, and
a strong cnidobattery on the dorsal side ; the terminal filament is a simple thin tubule,
similar to the pedicle. Four other genera (Stephanomia, Phyllop>hysa, Anthemodes,
and Cupulita) have the same form of the tentillum, but with this difference, that a
campanulate involucrum arises from the distal end of the pedicle and encloses the
proximal part of the cnidoband (PL XV. fig. 11). This involucrum is complete in four
other genera (Crystallodes, Agalma, Cuneolaria, and Agalmopsis) ; the simple terminal
filament in these is replaced by a tricornuate appendage, an odd median terminal
ampulla, and two paired, often spirally coiled lateral horns (PI. XVII.). The highest
degree of development, finally, is attained by Lychnagalma; the long cnidoband, enclosed
in a complete involucrum (or cnidosac), bears at its distal end a very large, hydrostatic,
terminal ampulla surrounded by a corona of eight radial horns (PI. XVI.).

Palpons. — All the Agalmidse possess a number of hydrocysts on the siphosome, either
true (mouthless) palpons, or excreting cystons (with a mouth). The distinction between
i hem is often difficult and requires further accurate observations. Usually each cormidium
(with ;t single siphon) possesses several (four to six or more) palpons ; but sometimes

REPORT ON THE STPHONOPHOR^E. 219

only a single one or a group of two. The palpons are united in a bunch, attached
to the basal insertion of the siphon, in the ordinate corrnidia of the Stephanomidse ; they
are isolated, attached immediately to the trunk, and scattered between the siphons, in
the dissolved corrnidia of the Halistemniidse ; sometimes their succession is regular, at
other times irregular. Usually one palpon (or cyston) is in direct connexion with the
gonodendra, whilst others are independent of them. The palpons are thin-walled,
cylindrical, very contractile and movable tubes, closed at the distal end, which is armed
with thread-cells. Sometimes the distal part of the palpon is separated by an annular
constriction and forms a subspherical cavity, in which a group of crystals or concretions
(like an otolith) is turned round by the ciliated entoderm, as in an otocyst.

Cystous. — Hydrocysts with a terminal mouth opening, or cystons, occur very
frequently (perhaps even constantly ?) in the Agalmidaa ; they were formerly confounded
with the similar mouthless palpons. They are larger than the latter, with a thicker
entoderm, which is partly glandular, and often coloured (red or brown). The fluid
secretion, or the pigmented, granular or crystalline masses secreted by it, are ejected
by the distal mouth, or rather the anal opening, which is closed by a muscular sphincter.
Sometimes the distal part is separated from the dilated middle part by an annular
constriction (PI. XV. figs. 8, 9). I have never found more than a single cyston in each
cormidium, whilst the number of palpons is usually large and variable.

Palpacles. — Many Agalmidae, but not all, possess a number of long and thin palpacles,
feeling or tasting filaments. Usually a single palpacle (or " accessory tentacle ") is
attached to the base of each palpon and probably also of each cyston. But in some
species they have not been described ; possibly they were either overlooked or lost
accidentally. Each palpacle is a very slender cylindrical tubule, the muscular wall of
which is very expansible and contractile, the cells of the exoderm covered with palpocds
and partly containing small cnidocysts.

Gonostyles. — All the Agalrnidae have monoecious corms and monoclinic corrnidia; each
cormidium possesses a male and a female gonodendron. These arise sometimes from a
common pedicle, at other times separated from two neighbouring gonostyles. The
ordinate corrnidia of the Stephanomidse always bear a small pair of gonostyles, a male
and a female, attached to their common trunk near the siphon. The loose corrnidia
of the Halistemmidas, however, exhibit a variable arrangement. Sometimes a monoclinic
pair of gonodendra, united with a palpon or cyston, arises from each internode, midway
between two neighbouring siphons ; at other times each internode bears two to four or
more pairs of gonodendra ; and sometimes their disposition is quite irregular, numerous
male and female gonodendra being scattered irregularly along the whole trunk of the
siphosome. Usually the gonodendra are small clusters, and their gonostyles simple or
little branched. The female gonophores are smaller and more numerous than the male.
Their umbrella is usually well developed, pedunculate, but sometimes rudimentary.

220

THE VOYAGE OF H.M.S. CHALLENGER.

The ovaria are ovate or subspherical, each with a single large ovum only, which is
often surrounded by an irregular net of spadicine canals (PL XV. fig. 15 ; PI. XVIII.
fig. 16). The spermaria are more oblong, spindle-shaped, cylindrical or club-shaped, with
a simple central spadix (PI. XV. fig. 14; PI. XVIII. fig. 17).

Ontogeny. — The development of the fertilised egg and the peculiar metamorphosis of
the larva (Physonula) arising from it, is known only in a few Agalmidse. It was first
described by myself in 1869, in Crystallodes rigidum (84, Tab. vi.-xiii.) ; afterwards by
Metschnikoff, in 1874, in Halistemma rubrum, Cupulita picta, and Agalmo2)sis sarsii
(85, Taf. viii.-xii.), and finally by Fewkes in Agalmopsis elegans (89).

I. Subfamily

CRYSTALLODIN.E.

Siphosome short and
rigid, about as
long as the nrscto-
some. Trunk of <
the siphosome
stiff, scarcely con-
tractile, densely
covered with thick
prismatic or sphe-
roidal bracts.

II. Subfamily

AnTHEMODINjE.

Siphosome very long
and movable,

much longer than
the nectosome.
Trunk of the
siphosome very
extensible and
contractile, loosely
covered with thin
scales or folia-
ceous bracts(rarely
with prismatic
bracts).

Synopsis of the Genera of Agalmidse.

Tentilla with a simple terminal filament, . 41. Stephanomia.

42. Crystallodes.

Cormidia ordinate.
Internodes free,
covered only with
bracts. Palpons «
and gonostyles at
the base of the
siphons.

Tentilla tricornuate, with a triple terminal
filament, ......

Cormidia loose
Palpons and go

Tentilla with a simple terminal filament,

to the inter 1 Tentilla tricornuate, with a triple termiual
nodes, between mament' • • • • •

the siphons. [

Cormidia ordinate.
Internodes free,
covered only with
bracts. Palpons <
and gonostyles at
the base of the
sijjhons.

Tentilla with a simple terminal filament, .

Tentilla tricornuate, with a triple terminal
filament, ......

43. Phyllophysa.

44. Agalma.

45. Anthemodes.

46. Cuneolaria.

Cnidoband naked,

without involu-

Tentilla with a

cre,

47a

Halistemma.

simple terminal •

filament.

Cnidoband envelop-

Cormidia loose.

ed by a campanu-

Palpons and go-

late involucre,

476

Cupulita.

nostyles attach-

ed to the inter- *

r Terminal ampulla of

nodes, between

the tentilla, with

the siphons.

Tentilla tricornuate
or multicornuate,
with a triple or
multiple terminal
filament.

two lateral horns,

Terminal ampulla of
the tentilla, with
a corona of eight

48.

Agalmopsis.

.

radial horns,

49.

Lychnagalma.

REPORT ON THE SIPHONOPHORJE. 221

Genus 41. Stephanomia? Peron et Lesueur, 1807.

Stephanomia, Peron et Lesueur, Voyage aux terres australes.

Definition. — Agalmidse with a short and rigid siphosome, the trunk of which is
scarcely contractile. Bracts with small intervals. Cormidia ordinate, with free inter-
nodes, in a single, straight, ventral series. Tentilla with a simple terminal filament.

The genus Stephanomia is the oldest known form of Agalmidse, and was founded in
1807 by Peron for an Australian Physonect, of which his collaborator Lesueur has left
an excellent picture (14, pi. xxix. fig. 5). The figure represents the siphosome only,
without the nectosome ; but fortunately I had the opportunity during my residence in
Ceylon (in December 1881) of examining a complete living specimen of a closely allied
species. The cylindrical siphosome of this Indian Stephanomia nereidum had exactly
the same form as that of the Australian Stephanomia amphitrites in Lesueur's figure,
except the special form of the bracts ; these are all tridentate in the latter, and
arranged very regularly in four longitudinal series ; whilst in the former they were
provided partly with three, partly with five teeth, and arranged in six less regular
series. The long internodes between the cormidia were free, and the yellowish
gonostyles attached near the base of the red-coloured siphons. The biserial nectosome
composed of twelve complete nectophores, had nearly the same form as that of Crystal-
lodes vitrea (PI. XVII. figs. 1-3). The position of the quietly swimming animal was
the same as in Lesueur's figure, the trunk lying horizontally and the cormidia forming
a rectdinear series on its ventral side ; the siphons and tentacles, therefore, depending
vertically. The same position is exhibited also by the similar Agalmid, which Huxley
afterwards described as Stephanomia amphitrites (9, pi. vi.); but this has loose cormidia,
and belongs probably to Phyllophysa (Genus 43).

Genus 42. Crystallodes,2 Haeckel, 1869.
Crysfallodes, Hkl., Entwickelungsgeschichte der Siphouophoren, p. 43.

Definition. — Agalmidaa with a short and rigid siphosome, the trunk of which is
scarcely contractile. Bracts with small intervals. Cormidia ordinate, with free inter-
npdes, in a single, straight, ventral series. Tentilla tricornuate, with a terminal ampulla
and two paired horns.

The genus Crystallodes was established by me in 1869 for an Atlantic Agalmid,
the complete anatomy and ontogeny of which I observed in January and February 1867,
during my residence in the Canary Island Lanzerote (84, p. 43, Taf. vi.-xiii.). Another
closely allied species, differing from the Atlantic Crystallodes rigida mainly in the
special form and arrangement of the bracts, was examined by me fifteen years after-

1 Stepha?wmia== Corona, arf^ai/afcu. i On/staWocfes=Crystal-shaped, k^wtxI^uZv;.

222 THE VOYAGE OF H.M.S. CHALLENGER.

wards in Ceylon, in January 1882 ; it is figured in PL XVII. of this Report. A third
species may be an Agalmid, from the Tropical Pacific, the siphosome of which was
floured by Lesson under the name Plethosoma crystalloides (22, pi. iv. fig. 2) ; the
nectosome was detached in the only specimen observed. A fourth species is the North
Pacific form, which Mertens observed in 1827 (lat. 42° N., long. 210° E.), and of
which Brandt has given a short description under the name Agalma mertensii (25,
p. 34). I had recently the opportunity of comparing the excellent pictures (unfortunately
not published) which Mertens had executed most carefully from the living animal.
They have convinced me that this Crystallodes mertensii is a peculiar species, differing
in the special form of the nectophores and the arrangement of the bracts.

Crystallodes vitrea, n. sp. (PL XVII. ).

Habitat. — Indian Ocean, Ceylon (Belligemma), January 1882 (Haeckel).

Nectosome (upper half of figs. 2, 3 ; fig. 1, lateral view, from the left side; fig. 2,
dorsal view ; fig. 3, ventral view). — The swimming apparatus in the single specimen
observed was 14 mm. long, 8 mm. broad, and composed of an apical pneumatophore and
of five pairs of opposite nectophores, besides some undeveloped buds on the base of the
former. The axial trunk of the nectosome is a slender colourless tube, slightly undulating;
its uppermost part is the thin pedicle of the pneumatophore, and was often stretched by
the swimming animal in the usual position, with horizontally lying trunk (fig. 1) ; the
pedicle of the pneumatophore was often bent upwards, and formed a right angle with the
trunk, so that the float stood vertically. The column composed of the nectophores is a
six-sided amphithect prism, corresponding to the regular union of the opposite pairs (fig. 6).

Pneumatophore (figs. 1-3, p). — The float is small, ovate or pyriform, with a red
pigment-spot at the apex. Outside are visible four equidistant longitudinal lines, the
insertions of the four vertical septa, which divide the pericystic cavity of the pneumato-
phore into four radial chambers.

Nectophores (figs. 1, 12, lateral view; figs. 2, 10, dorsal view; figs. 3, 9, ventral
view ; fig. 8, basal, fig. 7, apical view). — The cartilaginous umbrella of the nectophores is
strongly compressed from both faces, so that the proportion of the frontal diameter to the
principal and the sagittal axis = 3 : 2 : 1. The principal axis is nearly horizontal.
The two large faces, upper dorsal and lower ventral, are nearly parallel and hexagonal
in outline, the former slightly convex, the latter concave, with a prominent crest in the
ventral median line ; from this arises the short pedicle which attaches the nectosac to
the trunk. The proximal half of the umbrella is wedge-shaped, thickened towards its
equator, with a deep apical incision by which the two paired auricles or apical horns
embracing the trunk are separated. The narrow lateral faces of the nectophores (right

REPORT ON THE SIPHONOPHOR^E. 223

and left) are triangular in the proximal half, quadrangular in the distal half, which is
separated from the former by an equatorial crest. The distal (or basal) face, which
encloses the small ostium of the nectosac (fig. 8, v), is small, and nearly square.

Nectosac. — The subumbrella, placed in the distal half of the nectophore, is cordiform
or hammer-shaped, with an odd distal part bearing the mouth, and two paired lateral
parts, which expand right and left ; the three parts are subequal in size and similar in
the quadrangular outline, seen from the face. The frontal axis of the nectophore passes
through the broad proximal face of its subumbrella. The lateral view of the latter is
oblong. The course of the four radial canals is as usual, straight in the two sagittal
vessels (shorter ventral and longer dorsal), complicated and bent with three loops in the
two paired lateral vessels (compare pp. 189, 216, and figs. 6-13).

Siphosome (lower half of figs. 2, 3; fig. 1, lateral view, from the left side; fig. 2,
dorsal view ; fig. 3, ventral view). — The siphosome of the single specimen observed
possessed five fully-developed eormidia, and was in size (length as well as breadth) one
and a half times as large as the nectosome ; it equalled the latter in rigidity, and pre-
sented a glassy cylinder of 20 mm. in length and 12 mm. in diameter. Its axial trunk
was nearly straight, and bore on its ventral median line the five equidistant ordinate
eormidia. These occupied in the swimming animal (with horizontal trunk) only the
ventral half of the siphosome, whilst its dorsal half was exclusively composed of bracts.
All the siphons depended from the ventral side, and the long tentacles were prominent only
on this side ; in the same form which I have figured in the case of Crystallodes rigida
(84, pi. x. figs. 65, 66). The same characteristic form is clearly represented in an
excellent (unfortunately not published) figure of Crystallodes mertensii, drawn from life
by Mertens in 1827.

Cormidia (fig. 4). — Besides numerous buds of undeveloped eormidia, placed at the
top of the trunk of the siphosome (immediately beyond the nectosome), there were
attached to the ventral median fine of the trunk in the specimen figured five equal,
well-developed and equidistant ordinate eormidia. Each of these is composed of the
following parts arising from a common base : — (1) a siphon with its tentacle ; (2) a group
of four (sometimes three or five) palpons ; (3) a group of bracts (of the same number ?) ;
(4) a male gonodendron ; and (5) a female gonodendron. The equal intervals between
the cormidia, or the free internodes of the stem, were only covered by thick prismatic
bracts, densely attached one to the other.

Bracts (figs. 1-3, b ; figs. 14-16). — The hydrophyllia are thick glassy polyhedral bodies
of cartilaginous consistence, completely transparent, similar to colourless crystals. They
are easily detached from the stem, and offer very different forms, partly subregular,
partly irregular. The majority are wedge-shaped or obliquely pyramidal, with a
tapering proximal end attached to the trunk, and a truncate facetted distal face. The
upper face of the bracts is usually somewhat convex, the lower concave, and the outer

224 THE VOYAGE OF H.M.S. CHALLENGER.

(or distal) face divided by several crests into trapezoidal facettes (mostly three, four, or
five). Since the fundamental form of the cylindrical siphosome is bilateral, with
symmetrical right and left halves, the paired bracts corresponding in both halves are
so symmetrically disposed on both sides of the median plane (or the sagittal plane of
the siphosome) that the panelled surface of the carapace offers an elegant and very
regular pavement. Their special arrangement on the different sides of the siphosome is
intelligible by comparison of figs. 1-3. Since the free terminal facettes on the surface
of the scale-carapace are slightly concave, and their edges touch one another, the
prominent crests between them form an elegant network over the whole surface. This
pavement is in the Pacific Crystallodes mertensii, according to the beautiful figures of
Mertens, still more regular and elegant (with subregular rhomboidal meshes, apparently
arranged in eight longitudinal columns) than in our Indian Crystallodes vitrea. But
also in this latter eight subregular alternating longitudinal columns may be dis-
tinguished. The entire cylindrical carapace is very firm and scarcely variable in form,
since the protective scales may recede one from another only in a very slight degree.
On the ventral side there remain small, free clefts between them, through which the
tentacles proceed. Each bract encloses a simple blind canal, which runs in its median
line, near to the lower concave surface.

Siphons (fig. 4, s). — The pedicle of the siphon is rather long and thin, the basigaster
rudimentary. The wide cylindrical stomach exhibits eight longitudinal liver-ridges,
each of which is composed of a series of conical villi (about ten or twelve large villi in
each series). Each villus contains three to five roundish glossy and strongly refracting
bodies (probably glandular vacuoles). The proboscis is long and very extensile,
cylindrical, with eight strong longitudinal muscle-bands and eight alternating furrows
inside. Its distal mouth is armed with cnidocysts and may be expanded as a suctorial disc.

Tentacles (figs. 1, 5). — The tentacle which arises from the pedicle of each siphon is
very long, and bears a series of very numerous tentilla. The pedicle of the latter is
also long, and often spirally coiled. It bears a purple cnidoband, which is included
in a campanulate involucre and coiled up spirally in three to four turnings (fig. 5).
The terminal ampulla (ta) is large, spindle-shaped, and covered with long vibratile cilia.
On both sides of its base arise the two paired lateral horns, which are usually curved
or spirally coded (fig. 5, tc).

Palpons. — Each cormidium usually seems to possess four palpons attached to the
trunk immediately at the base of the siphon. They are much smaller than the latter,
simple, cylindrical, or spindle-shaped tubes, with a thin pellucid wall, very expansive
and contractile. Their pointed distal end is closed and armed with a number of cnido-
cysts (fig. 4,5). The inner and the outer surfaces are covered with long vibratile cilia. I
did not notice and so did not figure the presence of palpacles at the base of the palpons ;
but it may be that they were accidentally lost, or that I have overlooked them.

REPORT ON THE SIPHONOFHOP^E. 225

Gonodendra. — Each cormidium is monoclinic and bears two small grape-like, shortly
pediculate gonodendra, a male (fig. 4, h) and a female (fig. 4, f). Their clustered
gonophores are small and not very numerous. The ovaria, however, are more numerous
and much smaller than the spermaria. The umbrella is well developed in both sexes,
with four radial canals and a ring-canal. The manubrium of the gynophores is colourless,
ovate, or subspherical, and contains only a single large ovum, surrounded by a network
of irregular spadicine canals (similar to those of Agalma, PI. XVIII. fig. 16). The
manubrium of the androphores is much larger, cylindrical or spindle-shaped, milk-white,
and includes an axial spadix ; it is prominent more or less from the ostium of the
umbrella in the ripe androphores (as in Agalma, PL XVIII. fig. 17).

Genus 43. Phyllophysa,1 L. Agassiz, 1862.
Phyllophysa, L. Agassiz, Contrib. Nat. Hist. U. S., vol. iv. p. 369.

Definition. — Agalmidge with a short and rigid siphosome, the trunk of which is
scarcely contractile. Bracts with small intervals. Cormidia loose ; palpons and
gonostyles on the internodes, scattered between the siphons. Tentilla with a simple
terminal filament.

The genus Phyllophysa was established in 1862 by L. Agassiz for an Agalmid, of
which Quoy and Gaimard had figured a fragment only, under the name Stephanomia
foliacea (2, p. 74, pi. iii. figs. 8-12). The description and the figures, however, which
Quoy and Gaimard have left, are (as usual) far too incomplete and fragmentary to
determine with certainty the true nature of the form captured near New Guinea. I
retain the name of the genus, given by L. Agassiz, to designate that similar Agalmid,
the siphosome of which Huxley described and figured under the name Stephanomia
amphitrites (9, pi. vi.). It has loose cormidia, the palpons and gonophores being
attached separately to the trunk, between the siphons. It differs, therefore, essentially
from the similar Agalmid described under the same name by Peron and Lesueur ; this
has ordinate cormidia, with free internodes ; and the gonophores are attached to the
nodes at the base of the siphons (compare above, p. 221). Phyllophysa exhibits therefore
the same relation to the true Stephanomia which Agalma has to Crystallodes. To
avoid further confusion it seems advisable to call Huxley's form (9, pi. vi.) Phyllophysa
squamacea.

Genus 44. Agalma,2 Eschscholtz, 1825.
Agalma, Eschscholtz, Oken's Isis, 1825, p. 743; System der Acalephen, p. 150.
Definition. — Agalrnidse with a short and rigid siphosome, the trunk of which is
scarcely contractile. Bracts with small intervals. Cormidia loose ; palpons and

1 Phyllophysa = Leaf-bladder, tpiWov, (pioa. 2 Agalma = Ornament, oiyxKpx.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 29

2'26 THE VOYAGE OF H.M.S. CHALLENGER.

gonostyles on the internodes, scattered between the siphons. Tentilla tricornuate,
with a terminal ampulla and two paired horns.

The genus Agalma was established by Eschscholtz in 1825 for a new Physophorid
which he had observed living in the Northern Pacific (21, p. 743, Taf. v. fig. 17, and 1,
p. 150, Taf. xiii. fig. l). The figure and description are very accurate, and this Agalma
okenii must therefore be retained as the permanent type of the genus. It is closely
allied to Crystallodes, but distinguished from this by the loose cormidia and the
formation of a peculiar hydrcecium in the axis of the siphosome ; the thick bracts are
here so arranged that they enclose together a central cavity into which the contracted
stem with the cormidia may be retracted. Eschscholtz had already pointed out this
peculiar character as an essential difference from the similar Stcphanomia. The same
characteristic structure is very obvious in the new Indian species, which is described in
the sequel as Agalma eschscholtzii (PL XVIII. figs. 8-17). A comparison of its loose
cormidia with the ordinate cormidia of Crystallodes (PI. XVII.) Ulustrates their
distinction ; the siphons and tentacles in this latter issue separately between the bracts, in
a ventral series ; whilst they issue in the former, crowded in a bunch, from the basal
ostium of the hydrcecium. The same seems to be the case in three other species of this
genus, which are described by Dana as Crystcdlomia polygonata (North Pacific, 73, p. 459),
by Huxley as Agalma breve (9, pi. vii.), and by Leuckart as Agalma clavatum (8, Taf.
xiii. figs. 1-6). Later authors have described as Agalma a number of Agalmidse which
belong to other genera of this family.

Agalma eschscholtzii, n. sp. (PI. XVIII. figs. 8-17).

Habitat. — Indian Ocean, Ceylon (Belligemma), December 1881 (Haeckel).

Nectosome (fig. 8, upper half). — The swimming apparatus, in the single specimen
observed, was composed of an apical pneumatophore, and two opposite rows of necto-
phores, four in each row, besides some buds of undeveloped nectophores at the apex of
the tubular trunk, at the base of the pneumatophore. The trunk was undulating,
nearly zigzag, of a yellowish colour. The length of the nectosome is 40 mm., the
sagittal axis 30 and the frontal axis 20 mm.

Pneumatophore (fig. 8). — The float is ovate or pyriform, about half as long as a
nectophore, and covered with purple pigment-cells in the upper or apical half. The
lower or distal half is yellowish, and exhibits eight equidistant longitudinal lines, the
insertions of the eight vertical septa which divide the pericystic cavity of the pneuma-
tophore into eight radial pouches.

Nectop>hores (fig. 8, lateral view ; fig. 9, dorsal view). — The nectophores have
the form of a broad and flat wedge, with a deep median incision on the two-horned

REPORT ON THE SIPHONOPHOR.E. 227

apical or proximal side. The two lateral sides (right and left) are irregularly triangular,
with a prolonged proximal apex. The convex dorsal and the concave ventral faces are
bilaterally symmetrical and nearly hexagonal ; the two lateral edges of each hexagon are
slightly convex ; the two basal (or distal) edges are separated by the small ostium of
the nectosac, and the two apical (or proximal) edges by the deep axial incision which
embraces the stem. The two lateral horns or auricles, separated by the latter, are
nearly rhombic. The thickness of the wedge-shaped nectophore increases gradually from
the proximal apex towards the distal base, which is bilaterally truncated. In the
median line of the concave ventral side of the nectophore arises the short triangular
pedicle which attaches it to the stem.

Nectosac (figs. 8, 9, iv). — The subumbrellar cavity of the nectophore is small and
occupies only the middle part of its distal or basal half. It is oblongish in the profile
view (fig. 8), bicornuate in the dorsal view (fig. 9). The two symmetrical apical horns
are rounded. The basal mouth of the nectosac is narrow, and provided with three
scarlet ocelli or pigment-spots at the base of the velum, just on the three points where
three radial canals (the dorsal and the two lateral) inosculate into the marginal ring-
canal. The fourth (ventral) canal possesses no ocellus. The course of the four radial
canals is as usual (compare above, p. 216).

Siphosome (fig. 8, lower half). — The trunk of the siphosome is of about the same
length as that of the nectosome, and densely covered with very thick and large bracts,
which can recede only very little one from another, and permit, therefore, no consider-
able extension and shortening of the siphosome. This is almost globular, of 50 mm.
diameter. The bracts are so arranged that the subspherical outside of the siphosome
is completely loricated by the convex urticating abaxial face of the cartilaginous covering
scales ; these compose a continuous spiral, which is dexiotropic and ascends around the
undulating axial trunk in four to six complete turnings. The trunk forms the axis of
a subcylindrical or slenderly conical hydrcecium, i.e., a cavity which serves for the
reception of the contracted and retiring cormidia ; this protective cavity is closed around
by the carapace of the covering scales, and open only at the dilated distal end, whence
the siphons and tentacles can proceed (fig. 8, s).

Cormidia. — The polymorphous persons which compose the siphosome, siphons,
palpons, and gonostyles arise scattered and separately from the common trunk ; I was
however, not able, in the single specimen observed, to determine with full certainty
their peculiar arrangement, and the true composition of the loose cormidia. It
seemed to me that about half a dozen (or perhaps eight) siphons and tentacles arose
from the lower or distal half of the trunk of the siphosome, intermingled with a number
of palpons ; whilst distylic gonodendra, male and female separately, were attached to its
upper or proximal half, together with numerous palpons and palpacles, which were
protruded between the scales. Unfortunately most of the appendages were detached

228 THE VOYAGE OF H.M.S. CHALLENGES.

and the peculiar structure of the siphosome destroyed before I could begin its closer
anatomical examination.

Bracts (fig. 8, b ; figs. 10 and 11, dorsal view; figs. 12 and 13, profile view). — The
covering scales which compose the firm carapace of the globular siphosome are very thick
and hard wedges of cartilaginous consistence. Their thickness increases from the proximal
pedicle towards the middle part and decreases again towards the distal part, which is
usually trilobed or five-lobed. The form of the larger bracts is rather regular and sym-
metrical ; there are, however, intermingled, mainly in the proximal part of the siphosome,
numerous smaller bracts which have a more irregular form, and partly fill up the void
intervals between the former. The majority of bracts were detached from the stem
before I could examine their peculiar arrangement. Their lower or inner face is concave ;
and near to it runs in the median line the blind bracteal canal (figs. 10— 13, be); the
upper or outer face is convex and usually provided with three or five prominent ribs ;
each rib is three-sided, prismatic, and bears on its prominent abaxial edge a series of
large cnidocysts.

Siphons (fig. 8, s). — The feeding polypites, which proceed through the basal ostium of
the hydrcecial cavity just described, are of medium size, and of the form usual in Agal-
midfe. Their pedicle is long and slender, the basigaster small and ovate, the stomach
fusiform and provided with four double rows of red-brown liver glands ; the proboscis is
slender, very protractile, and ends in a mouth, which may be expanded in the form of a
circular or polygonal suctorial disc.

Tentacles (figs. 8, 14). — The long tentacle which is attached to the base of each
siphon bears a series of very numerous tentilla. Each tentillum (fig. 14) is composed
of a slender pedicle (tp) and a campanulate involucre (th) which encloses a purple
spiral cnidoband (tk) ; this exhibits seven or eight spiral turnings, and bears at its distal
end three appendages, a large spindle-shaped terminal ampulla (ta), and a pair of slender
lateral horns (tc).

Palpons and Palpacles (fig. 8, q, r). — The tasters are very numerous and seem to be
irregularly scattered over the entire stem of the siphosome, partly between the siphons
and bracts, partly connected with the gonostyles. They are very slender pellucid tubes,
cylindrical or spindle-shaped, closed at the apex, which includes a number of cnidocysts.
From their tapering base arises usually (or always ?) a long palpacle, a very thin and
mobile tasting filament, of the usual shape. The palpons as well as their palpacles are
stretched and protruded through the intervals of the bracts as well as through the basal
opening of the hydrcecial cavity.

Gonodendra.- — A small number of sexual clusters is attached to the trunk of the
siphosome, mainly (or exclusively) to its upper or proximal half(?). The corm is
monoecious, but the cormidia distylic, since each cluster contains gonophores of one sex
only. The umbrella is well developed in the gonophores of both sexes, campanulate in

REPORT ON THE SIPHONOPHOR^E. 229

the female (figs. 15, 16), subcylindrical in the male (fig. 17) ; the four radial canals are
connected at the ostium by a ring-canal. The ovate manubrium of the gynophores
(fig. 15) includes a single large ovum only, surrounded by an irregular network of anasto-
mosing spadicine canals (fig. 16, cy, compare p. 195). The cylindrical manubrium of the
androphores (fig. 17, hm) is very large, purple, prominent from the narrow ostium of
the umbrella, and contains a simple axial canal or central spadix.

Genus 45. Anthemodes,1 Haeckel, 1869.
Anthemodes, Hkl., Ueber Arbeitstheilung, &c, 38, p. 140.

Definition. — Agalmidaa with a long and movable siphosome, the trunk of which is
very contractile ; bracts with large intervals. Cormidia ordinate, with free internodes ;
palpons and gonostyles on the nodes. Tentilla with a simple terminal filament.

The genus Anthemodes was founded by me in 1869 for two different Atlantic
Agalmids which I had observed in the winter of 1866-67 during my residence in the
Canary Islands. One of these, figured as Anthemodes canariensis (38, Taf. i.) has
loose cormidia and belongs to Cupidita (Genus 47b). The second species, described
here as Anthemodes ordinate/,, and figured in Pis. XIV. and XV., has ordinate cormidia,
with free internodes, and may be retained as the true type of this genus. Fragments of
a similar species, Anthemodes articulata, have been found in a bottle in the Challenger
collection from the South Atlantic (Station 325) ; it seems to differ from the former
mainly in the thin fobaceous shape of the triangular bracts and the broader form of the
nectophores. The cormidia in Anthemodes are as regularly ordinate as in Stephanomia,
from which it differs mainly in the prolonged and very movable stem of the contractfle
(not rigid) siphosome.

Anthemodes ordinata, n. sp. (Pis. XIV., XV.).

Habitat. — North Atlantic, Canary Islands (Lanzerote), January 25, 1867 (Haeckel).

Nectosome (PL XIV. figs. 1-4). — The swimming apparatus was composed in the
only specimen observed of a small pyriform pneumatophore at the top of the tubular
trunk, and of eight nectophores disposed alternately in two opposite rows. Between
the uppermost nectophore and the base of the pneumatophore were visible a few buds
of young and undeveloped nectophores. Fig. 1 exhibits the nectosome from the lateral
and fig. 2 from the dorsal side. The swimming movements of this most elegant
Agalmid are very rapid.

Pneumatophore. — The float filled with air at the apex of the trunk is very small,
pyriform ; its pointed apex bears an octoradiate pigment-spot, composed of red-brown

1 Anthemodes = Flower-shaped, xudtpuly;.

230 THE VOYAGE OF H.M.S. CHALLENGEE.

polygonal cells. The dilated basal part presents eight longitudinal stripes, the external
insertions of the eight radial septa which divide the pericystic cavity of the pneumato-
phore into eight radial pouches.

Nectophores (figs. 1, 4, lateral view; figs. 2, 3, dorsal view). — The nectocalyces are
broad and short, truncate, conical in the tapering distal or basal part, provided with a
pair of large auricles in the dilated apical or proximal part. The frontal axis of the
latter is three times as long as that of the former, and twice as great as the principal
and the sagittal axis. The principal axis is directed obliquely from above and within
downwards and outwards. The upper or dorsal face is emarginate convex ; the lower
or ventral face concave, with a median groove, from which arises the short triangular
pedicle attaching the nectophore to the trunk. The two lateral auricles or apical wings
are nearly square, slightly bilobate on the lateral edge, and embrace the trunk in the
middle interval between two nectophores of the opposite series (an upper and a lowrer).
Each of the two paired wings is nearly as large as the odd basal part of the nectophore.

Nectosac (figs. 1-4). — The subumbrella of the nectophores has nearly the same form
as the surrounding exumbrella, from which it is separated by a rather thin but firm
jelly-plate. The two lateral auricles, however, are more deeply emarginate in the
former, nearly bilobate. The four radial canals are, as usual, of very different size
and form ; the two sagittal simply curved in the sagittal plane (the dorsal about twice
as long as the ventral) ; whilst the two lateral vessels (right and left) are much longer,
and exhibit a complicated undulating course (with four loops), which is intelligible by
comparison of figs. 3 and 4 (compare above, p. 216).

Siphosome (fig. 1). — The axial trunk of the siphosome is a slender and exceedingly
contractile cylindrical tube, many times longer than the trunk of the nectosome. It has
in the fully expanded state a length of 200 mm. or more, and is therefore ten times
as long as in the strongly contracted state, when it is only 20 mm. long. The corm
contracts very suddenly, and passes over rapidly from the former into the latter state.
The entire trunk is densely covered with innumerable prismatic bracts, and at regular
large intervals with a great number of ordinate cormidia. All the parts of the corm are so
hyaline and transparent, and for the most part so glassy and colourless, that the animal is
difficult to perceive, even in the fully expanded state and in motion. The swimming
power of the nectosome is great and the usual locomotion very quick.

Cormidia (PI. XIV. fig. 1; PI. XV. fig. 5). — Each cormidium is composed of a
large siphon (s), with a tentacle (t), a peculiar cyston (y), a male gonostyle (h), and a
female (f), and a number of bracts, which compose a protecting cavity for the former
parts. Besides, numerous other bracts cover the long intemodes between the cormidia,
which bear no other organs.

Bracts (PI. XIV. fig. 1; PL XV. figs. 5, b, 6, b, 10).— The hydrophyllia are extremely
numerous and of a peculiar form, difficult to perceive because of their glassy transparency,

REPORT ON THE SIPHONOPHOR^. 231

and subject to many variations. The majority of the bracts have the form of a flat obelisk,
or an irregular truncated four-sided pyramid, sometimes more approaching to a regular
four-sided prism, at other times to an irregular spheroid. There are intermingled, too,
three-sided and five-sided (or even six-sided) truncate pyramids between the prevailing
four-sided ones. The four trapezoidal lateral faces are usually of nearly equal size ; the
lower or basal terminal face is more or less concave, and about twice as large as the upper
or apical face. The edges are slightly convex and armed with a series of cnidocysts, a
larger one being prominent from each angle (fig. 10). A single blind bracteal canal (figs.
5 and 6, cb) arises from that corner of the basal face which is attached by a short
mobile pedicle to the trunk. The canal runs along the middle line of the concave basal
face to about its centre, and ends there in a club-shaped blind dilatation.

Siphons (figs. 5, s, 6, s, 7). — The single polypite of each cormidium is relatively large,
very contractile, transparent and colourless, and attached to the trunk by a short pedicle
(sp). The entire surface of the siphon is covered with very long vibratile cilia, arising
from the exoderm cells (fig. 7). The basigasteris rudimentary. The large stomach (sm)
is spindle-shaped, and contains inside four longitudinal rows of prominent hepatic villi,
each row composed of half a dozen conical villi (sv). Each villus seems to be a single
very much enlarged, glandular entoderm cell, which contains besides the nucleus a large
roundish hyaline vesicle, probably a digestive vacuole. Many stomachs were filled with
the eaten tentilla of the animal itself. The proboscis (sr) is a long cylindrical tube with
a very thick and mobile muscle-wall. It opens at the distal end by a very expansde
mouth, the edge of which is armed with thread-cells (fig. 7, so). The mouth may be
expanded and attached in the form of a circular or polygonal suctorial disc (fig. 5, ss);
this becomes sometimes as large as the entire cormidium.

Tentacles (PI. XV. figs. 5, t, 6, t, 7, t, 11-13). — The single tentacle, which is attached
to the base of each siphon, is very long and bears a series of very numerous tentilla.
Each tentillum is composed of a long pedicle (fig. 11, ts), an ovate cnidosac (k), and a
thin simple terminal filament (tf). The pedicle is beset with numerous papillate villi
(fig. 11, tv). The proximal half of the cnidosac is enclosed by a campanulate and ciliate
involucre, whilst its distal half is free and beset with numerous, very large, radially
distant cnidocils. The proximal base of the cnidosac contains a vesicular diverticulum of
the canal, the middle part a horizontal turning of the spiral cnidoband, beset on both
sides with a series of very large ensiform cnidocysts (kg) and above it a red pigment-
spot ; the distal end of the cnidosac is filled by globular cnidocysts. Whilst fig. 1 1
in PI. XV. exhibits the fully-developed tentillum, two immature stages of its develop-
ment are represented in figs. 12 and 13.

Cystous (figs. 5, y, 8, 9). — The single cyston, which is attached in each cormidium
near to the base of the siphon, is about half as large as the latter. It consists of three
parts : a short and small pedicle (yp), a large spherical thin-walled bladder, covered with

232 THE VOYAGE OF H.M.S. CHALLENGER.

an elegant epithelium of large hexagonal cells (fig. 8, y), and a distal proboscis. This hitter
is spindle-shaped, covered outside and inside with long cilia, and has in the middle a
spherical glandular dilatation, which contains a group of six to eight spherical (crystal-
line ?) concretions ; they are black in transmitted light, white in reflected light. The
pointed distal end of the cyston (figs. 5,8, yo) can be widely opened (fig. 9, yo) and the
excreta ejected through this anal opening.

Gonodendra. — Each cormidium is monoclinic, and bears at its base two small
clustered gonodendra, a male (fig. 5, h) and a female (fig. 5,f). The gonostyles are in
both sexes little branched, and the gonophores attached by simple pedicles ; their
umbrella is little developed or rudimentary. Each gynophore (figs. 5,f, 15) encloses
only a single, large, subspherical ovum, surrounded by a network of spadicine canals (fig.
15, xm). The manubrium of the androphores (figs. 5, h, 14) is large, club-shaped, and
contains a simple axial canal or central spadix (fig. 14, he).

Genus 46. Cuneolaria, Eysenhardt,1 1821.
Cuneolaria. Eysenhardt, 16, Nova Acta Acad. Nat.-Curios., t. x. pars 2, p. 369.

Definition. — Agalmidse with a long and movable siphosome, the trunk of which is
very contractile ; bracts with large intervals. Cormidia ordinate, with free internodes ;
palpons and gonostyles on the nodes. Tentilla tricornuate, with a terminal ampulla and
two paired horns.

The genus Cuneolaria was established in 1821 by Eysenhardt (16, p. 369) for an
Agalmid from the Northern Pacific, near the Sandwich Islands, of which he had observed
(in September 1817) only the detached nectophores (fig. 5, a), bracts (fig. 5, be), and
tentacles (fig. 5, d, e, f). These seem to be identical with some fragments of an
Agalmid which was captured by the Challenger in the same region in September 1875
(Station 269). The form of the nectophores, bracts, and tentacles agrees perfectly with
the figures of Eysenhardt. A fragment of the siphosome exhibited four ordinate cormidia,
separated by free internodes, of the same composition as in Anthemodes (PI. XV.).
Cuneolaria differs, however, from this latter in the form of the tentilla, which are
tricornuate, as in Crystallodes (PI. XVII.). Stephanomia heptacantha, captured by
Quoy and Gaimard near the Molucca Islands (2, pi. iii. figs. 16-18), is perhaps identical
with that species. Stephanomia imbricata of the same authors, from New Zealand (2, pi.
iii. figs. 13-15), may be another species of the same genus. The figures and descriptions
of the French authors are, however, too incomplete to determine with any certainty the
true anatomical composition and systematic position of these Agalmids. Cuneolaria
exhibits the same relation to Anthemodes that Crystallodes bears to Stephanomia.

1 Cuneolaria = Animal with wedge-shaped pieces, cuneolus.

REPORT ON THE SIPHONOPHORJE. 233-

Genus 47o. Halistemma,1 Huxley, 1859.
Halidemma, Huxley, Oceanic Hydrozoa, pp. 70, 129.

Definition. — Agalmidse with a long and movable siphosome, the trunk of which
is very contractile; bracts with large intervals. Corrnidia loose; palpons and gono-
styles on the internodes scattered between the siphons. Tentilla with a naked cnido-
band and a simple terminal filament.

The genus Halistemma was established by Huxley in 1859 for that Mediterranean
Agalmid, the first description of which Vogt had published under the name Agalma
rubrum (6, Tab. vii.-xi.). Perhaps identical with this species (from Nice) is another
Mediterranean form, which Kolliker has figured under the name Agalmopsis punctata
(4, Tab. iv.). Succeeding observers have described many different Agalmidse as
Halistemma, and mainly those forms which belong to the following genus Cupulita.
But the true Halistemma, according to the definition given by Huxley, differs from all
allied Agalmidse in the simple structure of the tentilla, which have the same form as in
Forshalia (PL IX. fig. 7,t; PI. X. fig. 23). The naked cnidoband is a simple spirally
convoluted riband without involucre, and bears a simple terminal filament. In all
other respects Halistemma. seems to agree with Cupulita ; but perhaps both genera
differ also in the structure of the palpons, which in the former seem to be mouthless, in
the latter provided with a terminal mouth (cyston).

Genus 476. Cupulita? Quoy and Gaimard, 1824.
Cupulita, Quoy et Gaimard, Voyage de l'Uranie, &c, p. 580.

Definition. — Agalmidse with a long and movable siphosome, the trunk of which is
very contractile ; bracts with large intervals. Corrnidia loose ; palpons and gono-
styles on the internodes scattered between the siphons. Tentilla with an involucrate
cnidoband and a simple terminal filament.

The genus Cupulita was founded in 1824 by Quoy and Gaimard for an Agalmid,
which Gaudichaud had captured at Port Jackson. The description of their Cupulita
howdichii (19, pi. lxxxvii. figs. 14-16) is very incomplete; but the figure which they
give of the nectosome is so similar to that of Halistemma tergestinum and some closely
allied species, that we employ the older name for these latter, instead of giving a new
name. Cupulita is in all respects very similar to the true Halistemma (rubrum or
punctatum), but differs in the form of the tentilla ; the spiral cnidoband is not naked
(as in the latter), but enveloped by a campanulate involucre. Another difference is
perhaps marked by the structure of the palpons, which in Cupulita are true excretory

1 Halistemma = Marine corona, x^io;, arcfi/^a. - Cupulita = Beset with cupules.

(ZOOL. CIIALL. EXP. — PART LXXYIL — 1888.) Ilbhh 30

234 THE VOYAGE OF H.M.S. CHALLENGER.

cystous (with a terminal mouth), whilst they seem to be mouthless in Halistemma.
Besides the oldest known form, the Australian Cupulita bowdichii, the following species
probably belong to this genus: — (1) Nanomia cara, A. Ag. (North-west Atlantic,
37, p. 200) ; (2) Anthemodes canariensis, Haeckel (North-east Atlantic, 38, p. 140,
Taf. i.) ; (3) Agalmopsis fragilis, Fewkes (Tropical Atlantic, 44, pi. v. fig. 2) ; (4) Agal-
mopsis elegans, Sars, partim! (North Atlantic, 27, Heft i. Taf. v.); (5) Halistemma
pictum, Metschnikoff, described in 1871 in the Russian language, Mediterranean); (6)
Halistemma tergestinum, Claus (Adria, 74, Taf. i.-v.).

Genus 48. Agalmopsis,1 Sars, 1846.
Agalmopsis, Sars, Fauna littoralis Norvegise, Heft i. p. 31, taf. v., vi.

Definition. — Agalmidse with a long and movable siphosome, the trunk of which is
very contractile ; bracts with large intervals. Cormidia loose ; palpons and gono-
styles on the internodes scattered between the siphons. Tentilla tricornuate, with a
terminal ampulla and two paired horns.

The genus Agalmopsis was described very accurately by Sars in 1846, and illustrated
by excellent figures. The North Atlantic Agalmidse, however, which are repre-
sented in his pis. v. and vi., belong to two (or even three?) different genera. The
first form, figured in pi. v., has simple terminal filaments of the tentilla, and belongs
therefore to the preceding genus Cupulita. The second form, represented in pi. vi.,
has tricornuate tentilla, with an odd terminal vesicle and two paired lateral horns. This
form may retain the original name Agalmopsis elegans, and represent the type of this
genus. Closely allied to it is the North American Agalmopsis catena, described by
Fewkes as Agalma elegans (43, viii. pis. ix., x.). A different species, Agalmopsis
dissoluta, Hid., inhabits the Tropical Atlantic. A fourth species is the Mediterranean
Agalmopsis sarsii, accurately described by Kolliker (4, p. 10, Tab. hi.).

Genus 49. Lychnagalma,- Haeckel, 1881.

Lychnagalma, Hkl., MS. Ind., and System der Siphonophoren, p. 40.

Definition. — Agalmidse with a long and movable siphosome, the trunk of which is
very contractile ; bracts with large intervals. Cormidia loose ; palpons and gono-
styles on the internodes scattered between the siphons. Tentilla multicornuate, with
a terminal ampulla and a corona of eight radial horns.

The genus Lychnagalma was established by me for a most elegant small Agalmid,
a complete specimen of which I had captured in December 1881, during my residence in

1 Ayalmopsis = Similar to an Agalma ; cLyahfiu, tyt;. 2 Lychnayalma = Candelabra ornament, Tivx"0?, dyct*pa.

REPORT ON THE SIPHONOPHORiE. 235

Ceylon. It is represented in PI. XVI. A similar species was described in 1879 by
Claus from the Mediterranean, as Agahnopsis utricularia (75, p. 199, Taf. xviii.).
Fewkes proposed for it in 1883 the generic name Calliagalma (42, xviii. p. 844); but
this name has been previously employed for an Insect. The peculiar and very remark-
able form of the tentilla distinguishes this interesting genus not only from the closely
allied Agahnopsis, but also from all other Agahnidse. Each tentillum bears a large
terminal ampulla, which is surrounded by an elegant corona of eight radial filaments.
The ampulla is a hydrostatic apparatus, lighter than the sea water, and directed upwards,
whilst the surrounding filaments are either horizontally expanded or move in different
directions. They form an extended net around the corm, well fitted for capturing prey.

Lychnagalma vesicularia, n. sp. (PI. XVI.).

Habitat. — Indian Ocean, Ceylon (Belligemma), December 1881 (Haeckel).

Nectosome. — The swimming apparatus is similar to that of Cupidita and Agahnopsis,
composed of a small apical pneumatophore (figs. 1, 2, p, 4) and two opposite series of
about sixteen alternating nectophores (figs. 1, n, 5, 6).

Pneumatophore. — The float is ovate, with an octoradial red-brown pigment-star on
the apex, and eight equidistant longitudinal ribs in the basal half. These are the
insertions of the eight vertical septa which divide the cavity of the pneumatophore into
eight radial pouches (fig. 4, pq). A horizontal annular septum, similar to a diaphragm,
divides the pneumatosac. somewhat beyond its equator, into two unequal halves ; the
superior larger half contains the chitinous pneumatocyst ; the inferior smaller half is lined
by a greenish, air-secreting epithelium, the pneumadenia ; both halves communicate by
a circular opening in the diaphragm, the pneumatopyle.

Nectophores (figs. 5, 6). — The swimming-bells are very similar to those of Cupulita
canariensis, rather square in the frontal view (fig. 6), irregularly pentagonal in the lateral
view (fig. 5). The convex dorsal face has a median rounded ridge, which fits into a
correspouding groove on the concave ventral face of the superjacent nectophore. From
the apical part of the latter arises a short triangular pedicle which attaches the bell to
the axial trunk. The two paired lateral facettes (on both sides of the median groove)
are produced into two apical horns, or nearly triangular-pyramidal auricles. The distal
base of the nectophore is obliquely truncate. The large nectosac is correspondingly
tripartite hammer-shaped, with an odd median basal or distal part, and two paired ovate
lateral pouches. Its four radial canals exhibit the usual shape, the two sagittal vessels
run simply curved in the median plane of the subumbrella, whilst the two lateral
vessels (figs. 5, 6, cl) are much longer and form several loops.

Siphosome (fig. 1). — The axial trunk of the siphosome is in the expanded state four

236 THE VOYAGE OF H.M.S. CHALLENGER.

to six times as long as in the contracted state, and as the trunk of the nectosome. It
bears twelve to sixteen siphons, and between them very numerous palpons and gonophores
scattered along the trunk. The cormidia are, therefore, loose. The entire siphosome
is densely covered by innumerable bracts, similar to Cv/pulita and Agalmopsis.

Bracts (figs. 7, 8). — The hydrophyllia are rather flat and broad scales, ovate or
triangular in outline, with a convex dorsal and a concave ventral side. Near the latter
a blind bracteal canal (be) runs in the middle line. The proximal end is tapering, and
attached by a short pedicle to the trunk. The broadened distal end is provided with
three to five short triangular teeth (figs. 1, 3, b).

Siphons (fig. 3, s). — The polypites are large, and very movable, provided with a
long pedicle. The ovate basigaster is narrow. The spindle-shaped stomach exhibits
eight hepatic ridges. The cylindrical proboscis opens by a mouth which may be expanded
in the form of a large and thin polygonal suctorial disc (fig. 3, ss).

Tentacles. — The long tentacle which is attached to the base of each siphon, in the
constriction between pedicle and basigaster, bears a series of numerous tentilla. The thin
pedicles of the tentilla are directed vertically upwards (fig. 1). The cnidosac contains a
long purple cnidoband coiled up spirally (fig. 9, tk), and enclosed by an ovate involucre
(th) ; the spiral turnings (six to eight) are in the proximal part horizontal, in the middle
part oblique, and in the distal part nearly vertical. The terminal ampulla (fig. 9, ta) is
ovate, larger than the cnidosac, and encloses in its distal apex an oil-globule, acting like a
hydrostatic float. The base of the ampulla is surrounded by a corona of eight slender
and very movable radially divergent filaments (fig. 9, tc).

Palpons. — The entire trunk of the siphosome is covered with scattered palpons, about
six to eight between every two siphons. They are slender, spindle-shaped, and very
movable tubes, the distal apex of which is armed with cnidocysts. Each palpon (fig. 3, q)
bears on its base a long and very thin palpacle, or a simple tasting filament (r).

Gonodendra. — The corm is monoecious, and the cormidia monoclinic. Numerous male
and female gonodendra are scattered along the trunk, about half a dozen between every
two siphons, two males and four females. The gonophores are larger and less numerous
in the male gonodendra (fig. 3, h) than in the females (/). Their structure, which I could
not sufficiently examine, seems not to differ from that of other Agalmidae.

Family XIV. Forskalid^e, Haeckel, 1 !
Forskalidx, Hkl., System der Siphonoplioren, p. 42.
Definition. — Physonectse polygastricae, with a long tubular stem of the siphosome,
bearing numerous siphons, palpons, and bracts, each siphon provided with a branched
tentacle. Nectosome multiserial, strobiliform, with several spiral rows of nectophores.
Pneumatophore with radial pouches.

REPORT ON THE SIPHONOPHORjE. 237

The family Forskalidse comprises those Physonectse polygastricse which have a long
tubular stem of the siphosome densely covered with bracts, and a strobiliform nectosome
composed of numerous spiral rows of nectophores. The siphons are very large, and
distinguished by a very long pedicle. They differ in these characters from most other
Physonectse, the nectosome of which is either biserial or quadriserial. The corona of
bracts of the Anthophysidse, however, may be compared with the spiral nectosome.

Although the Forskalidse are the largest and the most splendid of all Physonectse, and
some species occur in the Mediterranean and the Atlantic in large numbers, nevertheless
they remained perfectly unknown up to the year 1841. In that year Milne-Edwards
published the first description of two Mediterranean species, under the names Stepha-
nomia contorta and Stephanomia prolifera (71, p. 217, pis. vii.-ix.). It was completed
twelve years afterwards by Kolliker, who established for them the genus Forskalia (4,
p. 2, Tafs. i., ii.). Additions were afterwards made by Leuckart (8), Vogt (5), Keferstein
and Ehlers (33), and Claus (35). Recently (1881) an Atlantic species of Forskalia has
been described by Fewkes, under the name Stephanomia atlantica (44, p. 264, pis.
v., vi.). Another Atlantic species, Forskalia tholoides, was observed by me in 1866 off
the Canary Islands, and is described in the following pages (Pis. VIII. -X.).

A very remarkable and gigantic deep-sea Physonect, which probably belongs to this
family, was described in 1878 by Studer (40) under the name Bathypliysa abyssorum,
and in 1884 by Fewkes (45) as Pterophysa grandis. A similar form, of which I was able
to examine some fragments, makes it probable that these giants of the deep sea do not
belong to the Rhizophysidse (as the last-named author supposes) but to the Forskalidas.
Another new and interesting genus of this family, described in the following pages as
Strobalia, was observed by me in 1881 in the Indian Ocean, and illustrates the affinities
of this peculiar family.

Nectosome. — The swimming apparatus in the Forskalidse is larger, stronger, and more
highly developed than in any other Physonectse. The pneumatophore at the apex of the
trunk is small, but the nectophores are very numerous (usually more than one hundred)
and arranged in a continuous spiral. The whole nectosome is sometimes cylindrical or
conical, at other times more campanulate or hemispherical ; its different forms are
comparable to those of the different cones of firs. Its rounded surface is elegantly
panelled or facetted by the basal ostia of the nectophores, which are regularly disposed
in a cjuincuncial manner. The spiral line which connects the basal insertions of the
nectophores has four to eight or more turnings, and is usually lasotropic, therefore
opposite to the dexiotropic spiral of the siphosome. The genus Forskaliopsis is dis-
tinguished by the possession of palpons which are scattered between the nectophores.
The physiological activity of the nectosome is more highly developed thau in all the other
Physonectse, since the great number of nectophores and their pointing in all directions
enables the animal to perform a greater variety of swimming motions.

•j;;s THE VOYAGE OF H.M.S. CHALLENGER.

Pneumatophore. — The float at the top of the trunk is relatively small, usually ovate
or pyrilbrm, and pigmented in the apical part. Its outer wall (pneumatocodon) is
connected with the inner wall (pneumatosaccus) by a variable number of vertical radial
septa : four in Strobalia, six to eight or twelve in Forshalia and Forshaliopsis, sixteen
in Bathyphysa. The radial pouches or chambers of the pericystic cavity, which are
separated by these septa, are closed above, but open below in the common trunk,
beyond the funnel-cavity of the pneumatosac.

Nectophores. — The numerous nectocalyces, owing to their multiserial and spiral
arrangement on the nectosome, differ in form considerably from those of the other
Physonectse. Usually they are attached to the common trunk by a long pedicle of
conical or pyramidal form. Their umbrella is prismatic, with polygonal faces, produced
by the mutual pressure of the densely associated nectophores. The subumbrella is more
or less compressed in the sagittal direction, dilated laterally, often provided with two
lateral horns. Sometimes the exumbrella of the apical part, corresponding to the latter,
bears two prominent apophyses. The four radial canals of the nectosac, according to
that dorso-ventral compression, are usually of different sizes, the two lateral longer than
the two sagittal vessels. The ring-canal which connects them at the constricted ostium
of the nectosac is sometimes circular, at other times elliptical. Often some ocelli, red or
brown pigment-spots, are visible above the small velum, at the inosculation of the radial
canals. From the proximal union of the latter in the top of the nectosac arises a long
peduncular canal which runs through the pedicle of the nectophore and opens into the
axial canal of the trunk (PI. VIII. figs. 2, 3).

Siphosome. — Corresponding to the high development of the nectosome in the
Forskalidas, this interesting family surpasses all the other Physonectse also in the
complicated composition and extraordinary size of the svphosorae ; it attains in the
largest species a diameter of more than one metre in the fully expanded state ; in
Bathyphysa probably four to six metres or more ; in the strongly contracted state it
is much smaller. The numerous siphons are attached to the long trunk of the
siphosome by verj?' long peduncles, and these, as well as the trunk itself, are densely
covered with innumerable bracts. These envelop, densely crowded, the outer surface
of the contracted siphosome like a protecting carapace of scales. The entire form of
the siphosome is sometimes more cylindrical or inversely conical, at other times more
ovate or hemispherical ; fully expanded, with widely prominent and brilliantly coloured
appendages, it presents a most splendid spectacle.

Cormidia. — The number of the cormidia which compose the siphosome is usually
very large, thirty to fifty or more, in the larger species several hundreds (sometimes
more than five hundred). They are arranged around the axial trunk in a continuous
spiral, the turning of which is usually right-handed (or dexiotropic), in contrast to the
left-handed (or Inotropic) spiral of the nectosome. The trunk itself is correspondingly

REPORT ON THE SIPHONOPITOR^. 230

more or less spirally convoluted ; it is sometimes regularly articulate, with equidistant
segmental constrictions (in Strobalia and ForshaUa, PI. IX. fig. 7, a) ; at other
times the annular constrictions disappear and the cylindrical or slightly com-
pressed stem is not articulate (in Forshaliojisis and Bathyphysa). Respecting the
composition of the cormidia and their attachment at the trunk, we distinguish in the
Forskalidas ordinate and loose cormidia ; the former occur in Strobalia, the latter in
the three other genera.

The ordinate cormidia of Strobalia are similar to those of Stephanomia, Crystallodes,
Anthemodes, &c. Each cormidium is attached to a node of the trunk, or a constriction
of the stem, and composed of five different medusomes, three sterile (a siphonal, a
cystonal, and a palponal) and two fertile (a male and a female). The siphonal medusome
is composed of a pedunculate siphon, a tentacle, and a corona of bracts on the base of
the pedicle. The cystonal medusome consists of a cyston and a palpacle, surrounded
by a group of bracts. The palponal medusome is composed of a palpon with its
palpacle and a basal corona of bracts. The two sexual medusomes are represented by a
pair of gonodendra, which bear clustered gonophores, a male and a female. The
long internodes of the stem, between these ordinate distylic cormidia, are free and
covered only by small bracts.

The loose cormidia of the other three genera of Forskalidse may be derived
from the ordinate cormidia of Strobalia by dislocation of the associated medusomes.
The axial trunk of the siphosome preserves in ForshaUa the distinct articulation, whilst
this is lost in Forskaliopsis and Bathyphysa. The polymorphous medusomes which
compose the cormidia are here more or less separated, and the different persons and
their organs more or less scattered. In ForshaUa sometimes each cormidium is
composed rather regularly of four separate and different medusomes, attached at
intervals to the succeeding internodes of the stem. The first medusome is a siphonal
one (with siphon and tentacle), the second a cystonal (with cyston and palpacle), the
third a palponal (with palpon and palpacle), and the fourth a sexual (with a sexual
palpon and a monostylic gonodendron). But in the larger corms of Forskaliopsis and
of Bathyphysa the number and succession of medusomes in each cormidium seems to
be variable and often perfectly irregular.

Bracts. — The hydrophyllia or covering scales are always very numerous, and cover,
densely crowded, not only the stem of the siphosome, but also the long pedicles of the
single siphons, cystons, and palpons. Their number is even in the smaller species
several hundreds, and in the larger many thousands. The splendid Mediterranean
Forskaliopsis ophiura has more than five hundred siphons and on the pedicle of each
siphon more than a hundred bracts; the number of cystons and palpons, however,
amounts to two thousand to four thousand or more ; and since the pedicles of these
are also covered with bracts, the total number of the latter may amount to more than

240 THE VOYAGE OF H.M.S. CHALLENGER.

a hundred thousand. The form and size of the bracts are extremely variable and usually
more or less irregular ; their arrangement is very difficult to recognise, since they are
hyaline and easily detached. Usually they have the form of oblongish scales, with
concave lower and convex upper face ; the latter bears often three to five dentate ribs
or crests. The bracteal canal is always simple and runs along the lower face. The
great variety in size and form of bracts, in one and the same specimen, is exhibited
by figs. 10 to 18 of PL X.

Siphons. — The polypites of the Forskalidse are very large and highly developed,
and sometimes of an extraordinary size. The spindle-shaped siphons of Bathyphysa are
larger than those of any other Siphonophora? hitherto known ; they attain (in a strongly
contracted state) the length of 50 to 60 mm. and the thickness of 30 mm., and are
attached by pedicles of 200 mm. in length. But even in the smaller species of this
family the siphons and their pedicles attain a considerable size. The thin tubular
pedicles are usually covered with numerous bracts, in manner similar to the trunk of
the siphosome. The three parts of the siphon proper are usually well developed
(PL IX. figs. 7-9). The thick-walled basigaster, with masses of cnidocysts, is sometimes
divided by four longitudinal furrows into four equal quadrants. The wide stomach
bears usually eight, twelve, or sixteen longitudinal liver-ridges, coloured brown or red ;
these are wanting in Bathyphysa, being replaced by innumerable small hepatic villi
(similar to those of Athorybia). The muscular proboscis is very strong and extensible,
and provided with a widely expansible mouth. The opening of the mouth is often
surrounded by a corona of eight or sixteen short lobes.

Tentacles. — The form and structure of the single large tentacle which is attached
to the base of each siphon seems to be the same in all Forskalidae. The point of
insertion is in the constriction between the basigaster and the distal end of the long
pedicle (PL IX. figs. 7, 8). The number of equidistant tentilla or lateral branches,
which are inserted in the nodes of the regularly segmented tentacle, is very large.
Each tentillum (PL X. fig. 23) has a long pedicle (ts), a large spiral cnidoband (tk), and
a long terminal filament (tf). The number of the spiral turnings of the naked cnido-
band, which is not enclosed by an involucre, is variable in the single species, usually
two, three, or four. Its colour corresponds to that of the siphon (usually red). The
broad spiral riband is composed of many series of innumerable small paliform cnidocysts,
and of two simple lateral series of large ensiform cnidocysts (fig. 23, tk).

Cystons. — All Forskalidae possess a great number of hydrocysts or spindle-shaped
vesicles, which are attached to the base of the siphons in Strobalia, whilst they are
inserted into the trunk of the siphosome, between the siphons, in the three other genera.
They are usually described as " tasters." An accurate examination of them, however,
shows that three different forms of them must be distinguished, viz., cystons, palpons,
and gonopalpons. The two former bear a palpacle, wanting in the latter. The cystons,

REPORT ON THE SIPHONOPHOl^E. 241

anal or excretory vesicles (PL X. fig. 19), differ from the two other forms in the
possession of a terminal opening. They are much smaller than the siphons, and without
hepatic ridges, but exhibit a similar composition of four different segments ; a basal
pedicle (fig. 19, qp), a thick-walled hemispherical basigaster, at the base of which is
inserted the single long palpacle (r), a large thin -walled stomach (q), and finally a
conical or pyriform chromadenia, with a distal opening. This latter segment, which is
comparable to the proboscis of the siphons, is most characteristic of the cystous ; it is a
colour -gland, which produces a great mass of pigment -granules, and extrudes it through
the terminal anus. The dark glandular entoderm of the chromadenia is much thicker
than the colourless entoderm of the thin-walled stomach ; the pigment-granules secreted
by it are usually red or brown, sometimes intermingled with small crystals. When a
quietly floating Forskalia is touched, it suddenly discharges the contents of the
chromadenia, and makes the surrounding water dark and intransparent. Kolliker
(4, p. 8) and Leuckart (5, p. 17, and 8, p. 348) have already described this interesting
excretion ; but they suppose that there is no true opening at the distal end of the
cystons, and that the pigment is discharged by rupture of their wall. Repeated
observations on the living Forskalia tholoides have convinced me that the pyriform
red chromadenia, or the opaque distal portion of the cyston, possesses a constant
terminal opening. This anus or excretory opening, however, is difficult to observe in
the closed state (as is also the case in the mouth and the anus of many lower animals).
The opening has been observed too by Studer in the cystons of Baihyphysa abyssoimm,
which he has described as bracts (40, p. 20). The excretion of the pigment-masses and
the darkening of the water by it have probably the same physiological function as in the
Cephalopoda ; — to protect the attacked animal from its persecutors, and facilitate the
capture of food-animals.

Palpons. — Whilst one cyston only belongs to each cormidium of probably all
Forskalida?, the number of true palpons (formerly confounded with the cystons) is
usually much larger. In Forskalia there belong usually two palpons (arising from a
common pedicle) to each cormidium, in Forskaliopsis three, four, or more ; in some of
the largest forms a pediculate bunch of four to six or more palpons arises from the
trunk between each siphon and the appertaining cyston. The true palpons differ from
the latter mainly in the absence of a distal opening ; they are closed at the pointed
distal end, and communicate only by the pedicle with the tube of the trunk. Their
size is usually about half that of the siphons and cystons, but very variable according
to the different state of contraction. Sometimes the palpons are simple pyriform or
spindle-shaped vesicles, at other times divided by an annular constriction into a
smaller proximal and a larger distal part. The pointed apex of the latter is usually
provided richly with larger cnidocysts and long sensitive cnidocils, sometimes also
coloured by pigment. Their function is sensory. The long palpacle which arises from

(ZOOL. CHALL. EXP. — PART LXXVII. 1888.) Hhllll 31

242

THE VOYAGE OF H.M.S. CHALLENGER.

the base of each palpon is always a simple thin tasting filament, richly provided with
small cnidocysts and cynidocils.

Gonodendra. — The corms of all Forskalidse seem to be monoecious ; the cormidia are
usually monoclinic ; but in Bathyphysa perhaps diclinic. The gonodendra are distylic,
either male or female, in Bathyphysa and Strobalia, whilst they are monostylic in
Forskalia and Forskaliopsis. Each cormidium usually possesses in these two typical
genera a single pediculate gonodendron, which arises separately from the siphon and
cyston, and bears upon a common pedicle a spindle-shaped sexual palpon (PI. X. fig. 21)
and numerous roundish gynophores in the proximal part, oblongish androphores in the
distal part. Each female gonophore (/) develops only a single large ovum, each male
a large club-shaped spermarium (h). In some species two sexual palpons ("twin-
tasters"), more rarely three or four, are attached to the base of the hermaphroditic
gonodendron. There seems to be some variety in this arrangement. Strobalia differs
in the possession of two separate clustered gonodendra, a male and a female, both
arising separately from the common base of the ordinate cormidium.

Si/nopsis of the Genera of Forskalidm.

Nectosome without palpons.

Trunk of the siphosome articulate, with <

regular equidistant annular constric

tions.

Nectosome with palpons between the
nectophores.

Trunk of the siphosome not articulate,
without regular annular constric-
tions.

Cormidia ordinate. Gonodendra distylic, arising
from the base of the siphonal pedicles,

Cormidia loose. Gonodendra monostylic, alter-
nating with the siphonal pedicles,

Cormidia loose. Gonodendra monostylic, be-
tween the siphons, which have hepatic ridges
(no villi), .....

Cormidia loose. Gonodendra distylic, between
the siphons, which have hepatic villi (no
ridges),

50. Strobalia.

51. Forskalia.

52. Forskaliopsis.

53. Bathyphysa.

Genus 50. Strobalia,1 Haeckel, 1888.
Strobalia, Hkl., System del Siphonophoren, p. 42.
Definition. — Forskalidse with ordinate cormidia, and segmented trunk of the sipho-
some. Gonodendra distylic, arising from the base of the siphonal pedicles. Siphons
with hepatic ridges. Nectosome without palpons.

The genus Strobalia comprises some new species of Forskalidse, which are very
similar in general appearance to some smaller forms of the true Forskalia, but differ
from it in two important points. The cormidia are perfectly ordinate, not loose ;
and the gonodendra arc gonochoristic or distylic. Each cormidium of the siphosome is
composed of five different medusomes, three of which are sterile (a siphonal, a cystonal,
and a palponal) and two fertile (a male and a female). Each of the three sterile

1 StrobaUa= Marine spiral, <n^6fio;, «?uo;.

REPORT ON THE SIPHONOPHOR^E. 243

medusomes is again composed of three corresponding organs, viz.. a manubrium (a siphon,
a cyston, or a palpon), an appertaining filament (tentacle or palpacle), and a corona of
bracts (corresponding to the umbrella of the original medusa). The two sexual medu-
somes, or rather clusters of medusomes, are represented by two gonochoristic bunches of
gonodendra, a male and a female ; they arise separately from the common base of the
cormidium, from the basal insertion of the long pedicle of the polypites ; the male bunch
is smaller than the female. The form and structure of the single parts are essentially the
same as in the closely allied Forskalia ; but the internodes of the trunk, between the
equidistant cormidia, are covered only with bracts. Strohalia therefore exhibits a
similar relation to Forskalia as Anthemodes does to Halistemma, or Crystallodes to
Agalma. A beautiful species of this genus, Strohalia cupola, was observed living by
me in the Indian Ocean, and will be described in my Morphology of the Siphonophorse ;
a fragment of a similar species, Strohalia conifera, was collected by the Challenger in
the South Pacific (Station 288).

Genus 51. Forskalia,1 Kolliker, 1853.
Forskalia, Kolliker, Die Schwimrnpolypen von Messina, p. 2.

Definition. — Forskalidse with loose cormidia and segmented trunk of the sipho-
some. Gonodendra monostylic, arising from the trunk, separate from the siphonal
pedicles. Siphons with hepatic ridges. Nectosome without palpons.

The genus Forskalia, hitherto the only representative of this family, comprises in the
definition here stated those forms, the well-known type of which is the Mediterranean
Forskalia contorta, Leuckart (8), probably identical with Forskalia edwardsii of
Kolliker (4). The trunk of the siphosome is in this species, as web1 as in Forskalia
tholoides described in the sequel, distinctly segmented or articulate, with equidistant
annular constrictions, from which the single medusomes of the loose cormidia take
origin. Usually three different medusomes arise separately from the stem between
every two siphons, viz., (l) a sterile cyston with a palpacle; (2) a sterile palpon with a
palpacle; and (3) a sexual palpon, to the base of which is attached a clustered monostylic
gonodendron (with female gonophores on the proximal part and male gonophores on the
distal part). But sometimes the number of palpons is multiplied (often two or three
arising from a common pedicle), and their arrangement is more irregular. Another
difference between Forskalia and Forskaliopsis is seen in the presence of palpons in the
nectosome of the latter, wanting in the former. The general appearance of Forskalia is
more delicate and similar to Strohalia and to Agalmopsis. Probably to this genus
belong a number of different species inhabiting the warmer seas, e.g., Stephanomia
atlantica of Fewkes (44) ; but their distinction requires a further accurate comparison.

1 Forskalia, named in the honour of the celebrated naturalist, Petrus Forsknl (1775).

244 THE VOYAGE OF H.M.S. CHALLENGER.

Forskalia tholoides, n. sp. (Pis. VIII.— X.).

Forskalioma tholoides, Hkl., 1866, MS. Canar.
Habitat. — Lauzerote, Canary Islands, December 1866 (Haeckel).

Nectosome (PI. VIII.; PI. IX. fig. 6). — The swimming apparatus is very large,
campanulate or cupola-shaped, and has a diameter of 35 to 40 mm. The axial trunk
is a slender tubule, slightly curved and twisted spirally, of a reddish colour. Its apex
bears a small pyriform pneumatophore. The nectophores are very numerous, and so
densely aggregated that no intervals remain between them. They are arranged as
regularly in a continuous spiral as the bracts in a fir-cone. In the lateral view
of the nectosome of a middle-sized specimen (fig. 1) about sixteen to twenty longitudinal
rows of nectophores may be distinguished, and nearly the same number of alternating
transverse rows, so that their total number may amount to three hundred or four
hundred, and in the larger specimens more.

Pneumatophore (figs. 1, 6, p). — The float is an ovate, relatively small vesicle,
slightly prominent over the surrounding corona of nectophores at the top of the stem,
and coloured pink in the upper or apical half. Its outer membrane, or the pneumatoco-
don, is connected with the inner membrane, or the pneumatosaccus, by eight vertical
radial septa. These divide the cavity of the pneumatophore into eight radial pouches.
Its structure is the same as figured by Claus in Forskalia edwardsii, which, however,
has only six radial pouches (35, Taf. xlvii. fig. 16). The apex of the pneumatophore
(PI. X. fig. 24) has the form of an ocellus, a dark circular apical spot (simdar to a
closed opening), being surrounded by a clear colourless ring, and this again by a regular
pink pigment-cross. The four rays of this cross are forked, and the eight fork-branches,
composed of elegant pigment-cells, are divergent and equidistant towards the ecmator
of the pneumatophore, corresponding to the abaxial insertion of the eight internal
radial septa.

Nectophores (PL VIII. figs. 1-5). — The nectocalyces are irregularly prismatic, with
polygonal lateral faces produced by mutual compression. They are attached to the
axial trunk of the nectosome by long pyramidal pedicles (np). These are shorter in
the superior, longer in the inferior nectophores, where they attain double the length of
the umbrella. A long nectocalycine duct (ns) enters into the axial apex of the pyramidal
pedicle and runs in its axis towards the top of the campanulate subumbrella. It divides
here into four radial canals (nr), which are united above the small velum (v) by a ring-
canal (nc). Figs. 2-5 exhibit four different stages in size in the development of the
nectophores (fig. 5 a very young one).

Siphosome (PI. VIII. fig. 1, inferior half, seen in profile; PI. IX. fig. 6, apical
view). — The siphonophorous part of the entire corm, or the siphosome, has a very

REPORT ON THE SIPHONOPHOR^E. 245

different appearance according to the state of contraction of the different persons
composing it. In the strongly contracted state (fig. 6) it is nearly spherical, scarcely
larger than the dome-shaped nectosome above it ; in the highly expanded state it is
three or four times as large, and presents a most elegant aspect. The numerous
cormidia (forty to fifty in the figured specimen) are arranged around the central
spirally-turned trunk in a large dexiotropic spiral (or Delta-spiral), whilst the spiral
arrangement of the nectophores is an opposite one (lseotropic or Lambda-spiral), similar
to that of the cnidoband in the tentilla (PL X. fig. 23). The spiral axial trunk (fig. 7)
is articulate, and its pink central canal (etc) runs near the concave dorsal side.

Cormidia (figs. 1, 6, 7). — The cormidia, which compose the siphosome, are arranged
in this species in an irregular manner, and disposed in a different way from
those of other nearly allied species. It may represent, therefore, a separate genus,
Forshdioma. The trunk of the siphosome (PI. IX. fig. 7, a), which is distinctly
articulate, bears the series of cormidia on its convex ventral side, where they arise
from equidistant nodes, or annular constrictions of the stem. Usually each loose
cormidium is composed of four different medusomes, viz., (l) a long-stalked siphon,
with its tentacle and numerous bracts ; (2) a stalked cyston, with a palpacle and a group
of bracts ; (3) a stalked palpon, with a palpacle and a bunch of bracts ; (4) a gonostyle
with a sexual palpon and a monoclinic gonodendron. This kind of regular composi-
tion is probably the original one, and is characteristic of this species. It is, however,
not quite constant, but subject to some individual variations, which may be partly
accidental. A further accurate examination and comparison of the composition of
the loose cormidia is particularly required in this as well as in all other Forskalidse
hitherto described.

Bracts (figs. 1, 7,6, 10-18). — The innumerable hydrophyllia which cover the ir
siphosome are attached as well immediately to the trunk of it as to the pedicles of the
siphons, and to the bases of the pediculate cystous and palpons. Their number amounts
to more than a thousand in the largest specimens. The greatest number of these
bracts are small or of medium size, and of simple form (figs. 10-13); some of them
become larger and are developed in the form of large protective scales (figs. 7, b, 17,
18) covering the convex outside of the siphosome (fig. 1). These larger bracts are
three-sided prismatic, more or less asymmetrical, with a concave smooth lower or distal
face, and a convex dentate upper or proximal face. This latter bears usually a strong
dentate longitudinal crest, and the two lateral edges are also armed with a few teeth.
The smaller bracts have no crest and dentation ; they seem to fill up the intervals
between the larger, and are of very irregular form and different sizes (compare figs.
10-14). A blind longitudinal bracteal canal arises from the trunk and runs near the
concave inferior face of the bract.

Siphons (figs. 1, 6, s, 7, s, 8, 9). — The polypitesare large, 10 mm. to 15 mm. long, and

246 THE VOYAGE OF H.M.S. CHALLENGER.

attached to the distal end of pedicles of about the same length. These pedicles (fig. 7, sp)
are slender cylindrical tubes, very contractile, arid covered with a series of small bracts.
(The insertions of the detached bracts are visible in fig. 6, sp.) Usually four larger
bracts (comparable to a quadripartite umbrella) arise from the base of the pedicle'
and cover its whole length (fig. 7, b). The siphon itself has a subspherical thick-
walled basigaster, the cnidocysts of which are sometimes arranged on four square radial
plates (figs. 7, 8, sb). The ovate stomach (sm) possesses sixteen red longitudinal liver-
ridges, which are disposed regularly in a very remarkable manner (fig. 7, sh). Four
larger perradial ridges extend throughout the whole length of the stomach, while four
interradial, alternating with them, are shorter ; and between the former and the latter
are interpolated in the basal part of the stomach eight smaller adradial ridges. The
contractile proboscis (sr) has four stronger longitudinal muscular bands. Its distal
mouth exhibits sometimes eight, at other times sixteen, distinct lobes (fig. 8, so), which
are separated in pairs by constrictions and armed with cnidocysts (fig. 9).

Tentacles (figs. 1, 7, t, 8, t, 23). — The single tentacle, which arises from the basigaster
of each siphon (at the distal end of the long pedicle, fig. 8, sp), is very long and strong,
distinctly articulate, and beset with a series of very numerous tentilla which arise from
the equidistant nodes (fig. 7, t). Each tentillum (fig. 23) is composed of three parts, a
thin pedicle (ts), a large spiral cnidoband (tie), and a long slender terminal filament (tf).
The spiral cnidoband (or " cnidobattery ") is naked, without involucre, has usually four
open spiral turnings (like a corkscrew), and is composed of innumerable small paliform
cnidocysts, with a lateral series of larger ensiform cnidocysts on each side. The peculiar
arrangement, exhibited by the small fusiform cnidocysts in the terminal filament, is
represented in fig. 23a from its proximal part, figs 23b and 23c from the middle parts,
and fig. 23d from the distal part.

Cystous (PI. X. fig. 19). — The cystous or anal vesicles, one of which arises from the
trunk of the siphosome between every two siphons, are smaller than the latter, but larger
than the neighbouring palpons. Each cyston is composed of four segments, which are
comparable to those of the simdar siphon. The first segment is a slender and thin
pedicle (qp), not covered with bracts, and annulate towards the club-shaped distal end.
The second segment is a thick-walled hemispherical basigaster, with thickened exoderm,
full of cnidocysts ; it bears the long palpacle (r). The third segment (fig. 19, q) is a long
thin-walled cylindrical tube, comparable to the stomach of the siphon, but without the
characteristic liver-ridges of the latter ; it is separated by an annular constriction from
the basigaster at the proximal, and from the colour-gland at the distal end. The fourth
and last segment of the cyston is the colour-gland (chromadenia), a pyriform or conical
vesicle of a dark red colour, with a terminal mouth-opening, or rather an anus. Its
thick glandular entoderm secretes a mass of red pigment-granules, which often fill up and
expand the terminal vesicle. When the animal is attacked or irritated, it opens the anus

REPORT ON THE SIPHONOPHORiE. 247

spontaneously and ejects the masses of red pigment-granules which darken the sea-
water.

Palpons (PL X. fig. 20). — The tasters seem to occur between the siphons in variable
number and arrangement, sometimes a single one in each cormidium, at other times two
or even three associated. They are similar to the cystons, but smaller and without
a terminal opening. Each palpon is a spindle-shaped or pyriform vesicle, separated from
its thin pedicle by a ring composed of cnidocysts, which corresponds to the larger
basigaster of the cystons and siphons. The closed distal end is more or less pointed, and
armed with patches of small cnidocysts (fig. 20). From the cnidal ring of each palpon
arises, just as from the basigaster of each cyston, a very long and thin palpacle
(fig. 19, )•) or a tasting filament, which is beset with numerous small cnidocysts. The
variable arrangement of the latter is represented by fig. 19b in the proximal part, fig. 19a
in the middle, and fig. 1 9c in the distal part of the palpacle.

Gonophores (PI. IX. fig. 7, f, h ; PI. X. figs. 21, 22). — Each cormidium bears a
pediculate monostylic gonodendron, which is composed of a sexual palpon and numerous
clustered gonophores, females in the proximal part and males in the distal part. The
sexual palpon or gonopalpon (figs. 7, q. 21) is a spindle-shaped vesicle, which bears at
its base a pair of crescentic patches, composed of larger spherical cnidocysts ; its apex is
densely covered with smaller cnidocysts. The female gonophores (fig. 21,/) are pyriform
or subspherical ; each contains a single large ovum only, surrounded by a loose network of
irregular spadicine canals. The male gonophores (figs. 21, h, 22) are ovate or club-shaped,
with a simple central spadix (hx). The umbrella in both sexes closely embraces the
manubrium, and exhibits the usual four radial canals, connected by a very small
ring-canal above the velum.

Genus 52. Forskaliopsis,1 n. gen.

Definition. — Forskalidse with loose cormidia and unsegmented trunk of the sipko-
some. Gonodendra monostylic, arising from the trunk, separate from the siphonal
pedicles. Siphons with hepatic ridges. Nectosome with palpons.

The genus Forskaliopsis comprises those forms of Forskalidse, the typical represen-
tative of which is the Mediterranean Forskalia ophiura, Leuckart ; it differs from the
true Forskalia (hitherto confounded with it) in several important characters. The
trunk is not articulated, without annular constrictions, and everywhere densely covered
with innumerable bracts in the same manner as the long pedicles of the siphons. The
nectosome is distinguished by the presence of numerous tasting palpons scattered
between the nectophores (8, p. 352); these are wanting in Forskalia, and remind one
of the nectosome of Apolemia. The numerous cormidia in the large siphosome of

1 Forskaliopsis = Similar to Forskalia.

248 THE VOYAGE OF H.M.S. CHALLENGER.

Forskaliopsis seem to be looser, and their organs more irregularly scattered than in the
preceding Forskalia. The palpons of the former are much more numerous, often three,
four, or more arising from a common pedicle. Perhaps other constant differences may-
be found between these two genera, which are also rather different in external appear-
ance. Forskaliopsis is one of the largest and most splendid Physonectse ; its size
in the fully expanded state attains more than a metre, and the number of nectophores as
well as of siphons amounts in the larger specimens to five hundred or more, the number
of bracts to several thousands. I observed a gigantic representative of this splendid
genus, Forskaliopsis magnified, distinguished by the blackish-brown colour of the
siphons and cnidocysts, in 1881, in the Indian Ocean ; but unfortunately it was destroyed
before I could examine it sufficiently.

Genus 53. Bathyphysa,1 Studer, 1878.

Bathyphysa, Studer, Zeitschr. f. wiss. Zool., Bd. xxxi. pp. 21, 24.

Definition. — Forskalidse with loose cormidia and unsegmented trunk of the sipho-
some. Gonodendra distylic (?), arising from the trunk, separate from the siphonal
pedicles. Siphons with hepatic villi and a pair of lateral wings. Nectosome probably
with palpons between the nectophores (?).

The genus Bathyphysa (perhaps the representative of a separate family. Bathy-

physidse) was established in 1878 by Studer for a gigantic deep-sea Siphonophore,

which surpasses all other animals of this class in the extraordinary size of the siphons

and of the gonodendra. It was taken by the S.S. " Faraday" in 1875, on the occasion

of the third Atlantic Cable Expedition, and brought up by a grapnel from depths of

1000 and 1780 fathoms, in the North Atlantic (lat. 43° 45' N., long. 43° 36' W.). The

fragments of this most interesting genus, preserved in the Zoological Museum of Berlin,

are unfortunately very incomplete, partly without connection, and do not allow us to

compose a satisfactory idea of the complete structure and the natural affinities of the

genus. The strong tubular trunk of Bathyphysa abyssorum, which even in the highly

contracted state has a length of more than a metre, is divided into two halves of very

unequal thickness. The proximal or superior half is only 3 to 5 mm. in diameter and is

the trunk of the nectosome ; it bears at its apex an ovate pneumatophore of 20 mm. in

length, and beyond it numerous lateral apophyses (not mentioned by Studer, but figured

by him in fig. 28, loc. cit.), which are probably the bases of the pedicles of the detached

and lost nectophores. The distal or inferior half of the trunk is much thicker (10 to

15 mm. in diameter), laterally compressed, and beset in the ventral median line with two

series of numerous appendages, siphons and gonodendra alternating. The thin tubular

pedicles of the siphons attain a length of 20 centimetres, and bear numerous pisi-

1 Bathyphysa = Deep-sea-float, (ia.8vs, <?£w«.

REPORT ON THE SIPHONOPHORiE. 249

form prominences (" erbsengrosse Anschwellungen "), probably the basal parts of the
detached and lost bracts. The siphons themselves (in a strongly contracted state)
attain a length of 50 to 60 mm. and a thickness of 30 mm., and are therefore
much larger than in any other known Siphonophoras ; in the fully expanded state they
may have a length of half a metre or more. The basal half of the spindle-shaped
siphons is distinguished outside by the possession of two opposite lateral wings or crests.
Their whole inside is covered with innumerable small villi, which replace the wanting
hepatic ridges. The gonodendra, which seem to alternate with the siphons, are elegant
oblongish bunches 70 mm. to 80 mm. in length and 10 mm. to 15 mm. in breadth,
attached directly to the trunk by thin tubular pedicles of nearly the same length.
Each gonodendron is richly branched, and bears many hundreds of pediculate ovate
gonophores, about 1 to 1*5 mm. in diameter. The bad state of preservation did not allow
the recognition of their structure ; but all the gonophores in each gonodendron seemed to
be of the same sex.

Unfortunately the bracts as well as the nectophores were all detached and lost in
the fragments of the corm described by Studer ; but the great facility with which these
parts are detached in all Forskalidae explains their complete absence sufficiently ; and the
more so, as the mode of capturing this gigantic deep-sea form, brought up on a grapnel
from depths of 1000 to 1800 fathoms, must have injured the delicate corm in the most
violent manner. The tentacles which were originally attached to the base of the siphons
were also found separate from them ; they bore a series of tentilla, with ovate cnidosacs
12 to 15 mm. in length and 4 to 5 mm. in thickness; their spiral cnidoband had
numerous turnings. Similar to the siphons, but of half their size, and provided with
two larger longitudinal wings, were detached bodies, which Studer has described as
"bracts" (loc. cit., p. 20, Taf. iii. fig. 25) ; they are probably cystons.

Probably to the same genus belongs a gigantic deep-sea form, the detached siphons
of which Fewkes has described in 1886 as Pterophysa grandis, taken from a depth of
2109 fathoms in the Gulf Stream (45, Nr. xxxvi. p. 960, pi. x. figs. 1-3). Scattered
fragments and detached parts of another large Forskalid, probably closely allied, were
found in a bottle in the Challenger collection taken in the South Atlantic (Station
323, depth 1900 fathoms). It may be called provisionally Bathyphysa gigantea.

Family XV. Nectalid^e, Haeckel, 1888.

Nedalidx, Hkl., System der Siphonophoren, p. 41.
Definition. — Physonectse polygastricse, with a short vesicular stem of the siphosome,
bearing numerous siphons, palpons, and bracts, each siphon provided with a branched
tentacle. Nectosome with two or four rows of nectophores. Pneumatophore with radial
pouches.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 32

250 THE VOYAGE OF H.M.S. CHALLENGER.

The family Nectalidse is founded by me for the interesting new genus Nectalia
(PL XIIL), to which probably Sp>hyrophysa of L. Agassiz (36) is closely allied. They
have in general a similar organisation to the well-known Discolabidse (Physophora), but
differ from them essentially in the possession of a large protecting corona of cartilaginous
bracts at the apex of the siphosome.

Nectosome and Siphosome. — The corm of the Nectalidse is composed of a long columnar
nectosome and a flat coroniform siphosome. The trunk of the nectosome is a slender
vertical tubule, and bears either two opposite or four cruciate rows of nectophores ; and
at the apex a pneumatophore with four radial chambers. The trunk of the siphosome
is shortened, vesicular, and horizontally expanded in form of a spiral bladder, to which
are attached the following parts : — Uppermost a corona of bracts, beyond it a corona of
palpons or cystous, below a bunch of siphons and tentacles, and at the distal base a
group of clustered gonophores. Probably these polymorphous persons and organs are
arranged regularly in ordinate cormidia, as in Physophora ; but in the single specimen
observed by me it was impossible to make out this metameric arrangement with full
certainty. I suppose, however, that each nectophore belonged originally to a cormidium,
which was composed of the following parts: One bract, one palpon, one siphon with a
tentacle, and two gonodendra, a male and a female.

Pneumatophore (PI. XIIL figs. 1-3, p, 4). — The float, placed at the apex of the
siphosome, is in Nectalia pyriform, and exhibits four vertical radial septa, which connect
the outer with the inner wall ; the cavity of the pneumatosac is divided by them into
four large radial pouches. An opening at the apex of the pneumatocyst was not visible,
but there seems to be one at its base (just as in Physophora).

Nectophores (figs. 1, n, 5-8). — The column of nectocalyces in Nectalia is composed of
two opposite longitudinal rows, in Sphyrophysa of four cruciate rows ; the former bears
therefore the same relation to the latter as in the following family Physophora does to
Discolabe. The nectophores are similar in form and structure to those of many other
Physonectaa, and they embrace the trunk of the siphosome so fully by two apical horns
or wings, fitting in the space between two oblicpiely opposite nectophores, that the struc-
ture of the nectosome becomes very solid. The subumbrella of the nectophores has a
strong muscle-plate, and renders possible a very rapid movement of the swimming corm.
The velocity of the swimming Nectalia is much greater than that of most other
Physonectse, and comparable to that of Diphyes, Sagitta, and Loligo.

Bracts (figs. 1, 9-12). — The prominent character of the family Nectalidse is found
in the corona of bracts, which is attached to the apex of the siphosome immediately
beyond the base of the nectosome ; it is similar to that of the Anthophysidse, and is
wanting in the Discolabidse, which are otherwise nearly related. The bracts of Nectalia
are strong cartilaginous covering scales of a peculiar form and differentiation, especially
described below. They are raised and subhorizontally expanded in the quietly-floating

REPORT ON THE SIPHONOPHOR^E. 251

corm, whilst they form a closed bilaterally compressed calyx in the rapidly swimming
animal.

Palpons (q). — The corona of palpons, which is placed immediately beyond the corona
of bracts in the Nectalidse, is comparable to that of the Anthophysidse as well as of the
Discolabidae. The number of palpons, however, is much smaller than in the last two
families, and seems not to exceed that of the superjacent bracts. It may be that each
palpon and the appertaining bract originally composed a medusome, the former
representing its manubrium, the latter its reduced umbrella. The distal end of the
tubular, very mobile palpons, seems to possess a mouth-opening (fig. 2, qo), and in this
case they should be called cystous. Palpacles or tasting filaments were not observed.

Siphons (s). — The large polypites of Nectalia exhibit distinctly the four usual
segments, a short pedicle, a basigaster with very thick wall filled by cnidocysts
(figs. 2, 13, sb), a stomach sm). the inside of which bears longitudinal rows of glandular
villi (sv), and a very extensile and contractile proboscis with a thick muscular wall (sr).
The distal mouth of the latter is four-lobed (so).

Tentacles (t). — The long tubular tentacle which is attached to the base of each
siphon bears a series of numerous tentdla. The cnidosac of the latter includes in
Nectalia a strong, spirally-twisted cnidoband, and bears at its distal end a simple terminal
filament ; the latter is replaced in Sphyrophysa by an odd terminal vesicle and two
lateral horns. The difference between the two genera is therefore sinular to that
between Stephanomia and Agalma, or between Halistemma and Agalmopsis.

Gonophores. — The corms of Nectalia are monoecious and the corrnidia monoclinic,
since two clustered gonodendra, a male and a female, are attached near the base of each
siphon. The medusoid gonophores are very small and numerous, and have a reduced
umbrella. As usual, the spermaria are oblong or spindle-shaped, the ovaria roundish
or subspherical.

Genus 54a, Nectalia,1 Haeckel, 1888.
Nectalia, Hkl., System der Siphonophoren, p. 41.

Definition. — Nectalidas with a biserial nectosome, composed of two opposite rows of
nectophores. Cnidosacs of the tentUla with a simple terminal filament.

The genus Nectalia, as the type of this family, is represented by the North Atlantic
species figured in PI. XIII. It is similar to Physophora, but differs from it essentially
in the corona of large bracts which separates the biserial nectosome and the flower-shaped
siphosome. The cnidosacs of the tentilla bear a simple terminal filament.

The single specimen of this genus which I have examined, and which is described in
the secmel, I captured by scooping it up with a glass vessel without touching it, on

1 Nectalia = Swimming in the sea ; nixr^, ahiog.

252 THE VOYAGE OF H.M.S. CHALLENGER.

January 15, 1867, in the Canary Island Lanzerote. Quietly expanded on the surface of
the water, it had the form drawn in fig. 1 , but this lasted only a few minutes. Most of
the time the animal was in continuous very rapid motion, quite unusual among the
Physonectse. It swam through all parts of the vessel very quickly, without touching
its sides, with rapidly succeeding contractions of the nectophores. The siphosome was in
the swimming animal strongly contracted, the corona of bracts closed, and the strong
bilateral compression of the corm, with two sharp opposite keels in the sagittal plane,
seemed to be excellently adapted for the rapid swimming motion.

Nectalia loligo, n. sp. (PL XIII.).

Habitat. — North Atlantic, Canary Islands, Lanzerote, January 15, 1867 (Haeckel). ■

Nectosome (figs. 1-8). — The swimming apparatus is composed of a rather long tubular
trunk, which bears at the apex a pyriform pneumatophore, and beyond it a double series
of opposite nectophores in four pairs obliquely. The length of the nectosome is 20 mm.
to 25 mm., and about equals that of the largest bracts of the siphosome. There was a
group of buds of nectophores at the base of the pneumatophore, marking the blastocrene
of the nectosome, or its point of vegetation.

Pneumatophore (figs. 1, 2, 2>,p>, 4). — The float at the apex of the nectosome was in the
living animal pyriform, with a red apex and an oblongish pneumatocyst filling up its
upper half (fig. l,pf). Preserved in alcohol (fig. 4) it appeared under an altered form,
subcylindrical, with two annular constrictions of the included pneumatocyst (f>f)- The
pneumatosaccus surrounding the latter is rather wide, and connected with the pneu-
matocodon by four cruciate radial septa or vertical mesenteria {pi'). The pericystic
cavity of the pneumatophore, therefore, is divided into four radial pouches, (ps).

Nectophores (figs. 1, n, 3, in, buds, fig. 5, a young nectophore, figs. 6-8, adult necto-
phores, 6, dorsal view, 7, basal view, 8, lateral view from the left side). — The umbrella of
the nectophores is strongly compressed in the direction of the sagittal axis, which is
3 mm. or 4 mm. long, half as great as the frontal and the principal axes (both 6 to
8 mm. in length). The truncate basis, with the ostium of the nectosac, is directed
obliquely outwards, whilst the opposite apex has a deep square excision. The two lateral
horns or wings, which are separated by the latter, are square in frontal view (fig. 6),
triangular in lateral view (figs. 1, 8), of a three-sided prismatic form, and embrace the
trunk of the nectosome, so fitting in the interval between the two opposite nectophores
(superior and inferior) that they fill up the interval between them. The superior or
dorsal face of the umbrella is slightly convex, with a median sagittal groove, and fitting
exactly into the concave lower or ventral face of the next superior nectophore. In the
median line of the ventral groove arises a sagittal ridge, which bears a short pedicle

REPORT ON THE SIPHONOPHOR^E. 253

(fig. 8, cp), serving for the attachment to the trunk. The two lateral faces of the
umbrella, right and left, are strongly convex (figs. 6, 7).

Nectosac (w). — The subumbrella occupies about two-thirds of the nectophore, and is
also strongly compressed in the sagittal direction. Its upper or dorsal face is concave,
the lower or ventral convex. Its axial or proximal half is dilated, twice as broad as the
abaxial or distal half. The latter opens by a narrow triangular mouth (no), which is
surrounded by a small velum (v). The nectocalycine duct (fig. 8, cp), which enters
through the pedicle of the nectophore, divides on the top of the nectosac into four radial
canals of very different length and form. The shorter concave dorsal canal and the
longer convex ventral canal run straight in the sagittal plane ; whilst the two lateral
canals (right ex, and left cl) are about three times as long, and form not less than four
curved loops, the complicated course of which may best be seen by comparison of figs.
6-8. The small ring-canal, which connects the four radial canals at the mouth of the
nectosac, makes a simple bend in the dorsal half, a pair of loops in the ventral half
(fig. 7, cc).

Siphosome (fig. 1 drawn from the living specimen ; fig. 2 from the same dead, in
contracted state, after detachment of the bracts and nectophores). — The inferior half of
the corm, below the nectosome, has the aspect of a flower, which is compressed from two
sides, in the same direction as the bilateral nectosome. The trunk of the siphosome
(fig. 3, as) is an ovate vesicle, which bears a series of buds (is) in the median line of its
ventral side, as an inferior continuation of the superior series of buds of nectophores (in).
The polymorphous appendages, which arise from the bud series, are so disposed that
immediately beyond the nectosome a corona of bracts is expanded. Below this
follows a corona of cystous or mouth-bearing palpons, and inside of these a group of
siphons (s) with the tentacles (t) ; finally, at the distal base the bunches of gonophores.
When we compare the composition of the siphosome with that of a dichlamydeous flower,
then the bracts correspond to the calyx, the cystous to the petals, the siphons to the
stamens, and the gonophores to the pistils. If the animal floats quietly at the surface of
the sea, then the calyx is opened and the petals and stamens expanded (fig. l); but
when it swims quickly by the action of the nectophores, then the calyx is closed and
the appendages included in it form a dense, bilaterally compressed bunch.

Bracts (figs. 1, 9-12). — The corona of large and firm cartilaginous bracts or covering
scales, which expands beyond the nectosome and covers the other parts of the siphosome,
exhibits a very remarkable composition, not observed hitherto in any other Siphon ophorae.
The corona has an amphithect fundamental form, compressed from the two lateral sides
of the corm, and is composed of eight foliaceous, symmetrically arranged bracts (fig. 1).
A pair of larger and slender lateral bracts (figs. 11, 12) is placed on the two poles of the
frontal axis of the trunk (right and left) ; they are 25 mm. long, 5 to 6 mm. broad.
A second pair of bracts, which have the same breadth, but only one-third of the length

254 THE VOYAGE OF H.M.S. CHALLENGEE.

(fio\ 9), covers the two poles of the sagittal axis (dorsal and ventral pole), and lies there-
fore immediately beyond the two lowermost nectophores. Between the former and the
latter (in two crossed diagonal axes) lie two pairs of opposite bracts of medium size (fig.
10). Each bract has a concave ventral or axial face, and a convex dorsal or abaxial face,
in the median line of which arises a prominent crest or keel (bd). A simple bracteal canal
(eb) runs near the ventral side, in the median line, and ends blindly near the distal apex.
The two lateral margins form a pair of thin lamellar wings, each with a prominent tooth
towards the distal end. The base of the bract (bb) bears a curved hook, for insertion
into the trunk ; and the opposite distal apex is provided with a bunch of cnidocysts.
These are wanting, however, in the two large lateral bracts, which appear straight in
profile (fig. 12), whilst the other six have a sigmoidal curve (fig. 10). The two large and
very vigorous lateral bracts may act in the rapidly swimming animal like the so-called
"swords" in a sailing boat. Nectalia loligo has a more rapid swimming motion than
any other known Physonect, and agrees in this with Diphyes, Sagitta, and Loligo.

Palpons (q). — Immediately beyond the corona of bracts is placed a corona of palpons
or tasters, comparable to that of Physophora, but much less developed. The number of
palpons which are attached to the trunk close inside the base of the bracts seems to
correspond to that of the latter. Their body is a long and slender cylindrical tubule,
very mobile and flexible. The palpons may be perhaps better called cystous, since they
seem to possess a mouth-opening at the distal end (fig. 2, qo ?). I could, however, not
be absolutely certain on this point.

Siphons (figs. 1, 2, s, 13). — The number of fully-developed siphons was in the single
specimen observed four, and they were attached to the base of the vesicular trunk of
the siphosome, inside the corona of palpons. When fully expanded and prominent
between the bracts (fig. l) the siphons were longer than the latter (up to 30 mm.).
The short pedicle of the siphon bears a pyriform basigaster (sb), and upon this an
ovate, very dilatable stomach (sm) ; its inside exhibits eight to twelve or sixteen longi-
tudinal rows of prominent, glandular, red-coloured villi (sv). The following proboscis
(sr) is a cylindrical, very mobile tube with a thick muscular wall ; its entoderm is in some
siphons red. The mouth at its distal end is often dUated, and its opening, also reddish,
square or provided with four short lobes (so).

Tentacles (figs. 1, t, 2, 14). — Each siphon bears at its base a long tentacle,
beset with a series of numerous tentilla. The latter (fig. 14) have a long pedicle
(ts), a large cnidosac (tk), and a simple small terminal filament (tf). The cnidosac
has a peculiar form, being composed of two large subspherical ampullae (one proximal,
tku and one distal, tkin), and between both a cylindrical middle part (tkn), which
contains a large cnidobattery (tkir). This latter is a long spiral riband of four to
five coils, composed of innumerable small paliform cnidocysts (fig. 15) and two lateral
rows of large ellipsoidal cnidocysts (fig. 1G).

REPORT ON THE SIPHONOPHOR^E. 255

Gonophores. — The sexual medusomes are placed at the distal base of the siphosome,
below and inside the siphons. There seems to be a couple of clustered gonodendra (a
male and a female) attached to the base of each siphon, composing with it (and with
the appertaining palpon and bract) an ordinate monoclinic cormidium. The gonostyle
of the male as well as of the female gonodendron is richly branched, the number of
gonophores large, their size small. The spermaria are oblongish, the ovaria roundish,
as usual. The umbrella is reduced. The special structure of the gonophores, which
I could not sufficiently examine, seems to be similar to that of Physophora.

Genus 546. Sphyrophysa? L. Agassiz, 1862.

Spliyrophysa, L. Agassiz, Contrib. Nat. Hist. U. S., vol. iv. p. 368.

Definition. — Nectalidae with a quadriserial nectosome, composed of four cruciate
rows of nectophores. Cnidosacs of the tentilla with three terminal appendages, an
odd median ampulla, and two lateral horns.

The genus Spliyrophysa was established by L. Agassiz for the Physonect which Quoy
and Gaimard had found in the Tropical Atlantic (lat. 7° N.) in February 1829, and
figured under the name Physophora intermedia (2, p. 56, pi. i. figs. 10-18). As far as
it is possible to recognise it from their incomplete representation, it seems to be closely
allied to the preceding Nectalia, but differs from it in two essential characters of
generic value. The nectosome seems to be composed not of two opposite, but of four
cruciate rows of nectophores (as in Discolabe among the Physophoridse). The cnidosacs
of the tentilla are tricornuate, and bear at the distal end an odd median vesicle and two
paired lateral horns (as in Agalma, &c).

L. Agassiz also has placed in the same genus, Spliyrophysa, the similar Physonect
which Huxley had described as Agalma breve (9, p. 75, pi. vii.). But this species is
probably a true Agalma, and more allied to the form which Leuckart has described as
Agalma clavatum (compare above, p. 226).

Family XVI. Discolabid^e, Haeckel, 1888.

Discolabids, Hkl., System der Siphonophoren, p. 41.
Physophoridx, Huxley, et multor. autor.

Definition. — Physonectag polygastricse, with a short vesicular stem of the siphosome,
bearing numerous siphons and a corona of large palpons (instead of the wanting bracts),
each siphon provided with a branched tentacle. Nectosome with two, four, or more rows
of nectophores. Pneumatophore with radial pouches.

1 Spliyrophysa = Hammer-bladder, a(pSj«, <pw«.

256 THE VOYAGE OF H.M.S. CHALLENGER.

The family Discolabidse comprises those polygastric Physonectao, the nectosome of
which is well developed, with a long trunk and two or more series of nectophores, whilst
the trunk of the siphosome, without bracts, is shortened and subhorizontally expanded
in the form of a wide spiral bladder, the ventral periphery of which bears a series of
ordinate cormidia, protected by a corona of large palpons.

The well-known type of this family is the Mediterranean Physophora hydrostatica,
figured and described in 1775 by Petrus Forskal. Its accurate anatomical description
was given in the years 1853 to 1860 by Kolliker (4), Vogt (6), Gegenbaur (10), and
Claus (34). Huxley (9) established for this genus the family Physophoriadse and gave to
it the following definition : — " Physophoridse with nectocalyces, but without hydrophyllia.
The distal end of the filiform ccenosarc dilated. Tentacular branches with involucrate
sacculi. Pneumatocyst small." The name Physophoridse for this family has also
been retained by later authors ; but unfortunately it is employed with no less than
four different meanings, and therefore has lost all value (compare above, p. 186). It
may be, therefore, best to call this family Discolabidge, from another genus belonging
to it, Discolabe (Eschscholtz, 1, p. 155). A third genus is Stephanospira of Gegenbaur
(10, p. 67).

Nectosome. — The swimming apparatus of the Discolabidse is composed of numerous
large nectophores, arranged in various ways around the vertical tubular trunk, and of
an apical pneumatophore at the top of the common trunk. Usually (in the typical
Physophora) the nectosome is biserial (disticha), as in the Agalmidse, composed of two
opposite longitudinal rows of nectophores (usually four to six pairs). Discolabe differs
in having a quadriserial nectosome (tetrasticha), similar to Sphyrophysa ; it is composed
of four cruciate longitudinal series of nectophores (or of four to six quadriradiate coronas).
Stephanospira, finally, has a conical or multiserial nectosome (polysticha), similar to that
of the Forskalidae ; the nectophores are here very numerous and arranged in a long
continuous spiral, with four to six or more turns. The trunk of the nectosome, after
the detachment of the nectophores, is a cylindrical, or in the contracted state, spindle-
shaped bladder, which bears on its ventral side a lamellar longitudinal fold, like a
mesentery, and at the free edge of this a series of spirally convoluted folds, the
insertions of the detached nectophores. The tapering proximal end of the vertical
spindle-bladder is separated by a constriction from the pneumatophore, and the broader
distal end by a similar constriction from the inflated trunk of the siphosome (PI. XX.
figs. 9-12).

Pneumatophore (figs. l,p, 9-13, p). — The float filled with air has in the Discolabidse
the same structure as in the Agalmidae. It is ovate or subcylindrical, with a red
pigment-spot at the apex, and with a variable number (usually eight) of longitudinal ribs
in the outer wall. These arise in the lower half as eight (more rarely seven or nine)
vertical radial septa, which connect the inner with the outer wall and divide the

REPORT ON THE SIPHONOPHOR^E. 257

pericystic cavity into the same number of radial pouches. Claus(74, p. 22) and Korotneff
(50, 2>. 272) have described peculiar caecal canals in the wall of the radial septa ; but
these hypothetical canals are in fact solid fibres composed of exoderm cells, and arising
from the pneuraadenia (or the air-secreting exoderm of the infundibulum), as has been
shown by Chun (48, p. 514). The apex of the pneumatophore has no opening ; but there
is a stigma, or a constant opening through which the air is emitted, at the base of the
pneumatophore, in the median line of its dorsal side, opposite to the ventral buds of
the youngest nectophores ; its place corresponds to that point where, in the Auronectse,
the aurophore is situated. Keferstein and Ehlers (33, p. 3) have already described the
spontaneous emission of air by this stigma, and I have repeated the same observation in
the Canarian Physophora magnified (84, p. 35, pi. iii. fig. 26).

Xcctophores (PI. XIX. figs. 1-4). — The nectocalyces are in general very similar in
form to those of the Agalmidse. The bilaterally symmetrical umbrella is attached to the
trunk by a lamellar triangular pedicle, which arises in the middle line of its concave
ventral side. The opposite dorsal side is more or less convex. The principal axis is
directed obliquely from above and within, downwards and outwards, so that the apical pole
is situated more highly than the basal pole with the ostium. This latter is obliquely
truncate, often with a pah- of lobiform apophyses on the ventral side. The axial or
apical half of the nectophore is always much broader than the basal half, and provided
with a pair of auricles or apical horns which embrace the stem. Correspondingly, the
large nectosac, which is not much smaller than the surrounding umbrella, is cordate and
composed of three parts, a smaller odd basal part and a pair of large lateral lobes ; the
former is subcylindrical or subconical, the latter are subovate or trapezoidal. The four
radial vessels are of very different shape, since the two paired lateral canals enter into
the two dilated auricles ; they form here several loops, and are therefore much longer
than the two sagittal canals (shorter ventral and longer dorsal) which run simply
curved in the median plane of the nectosac. The circular canal which connects the
four radial canals above the insertion of the velum is small and ovate, corresponding
to the small ostium of the nectosac. (Compare 10, Taf. xxx. figs. 33-35 ; 34, Taf.
xxv. figs. 6-8 ; 27, Heft iii. Tab. vi. figs. 1-4, &c.)

Siphosome (PL XX. figs. 9-13). — The trunk of the siphosome in the Discolabidse
was regarded by all former observers as a simple sac-shaped and inflated dilatation of the
blind basal part of the trunk of the nectosome, and the general opinion was, that the
different appendages, beyond the corona of tasters, were more or less irregularly crowded
at its basal face (with loose cormidia). This error was not corrected until the year 1877,
when the excellent figures of Physophora borealis by M. Sars were published in the
third part of the Fauna littoralis Norvegias (27, Heft iii. Taf. v. figs. 1-6). This celebrated
observer had discovered, many years before, that the siphosome of Physophora is expanded
subhorizontally, beyond the nectosome, in form of a large, reniform, spirally-twisted sac,

(zool. CHALL. EXP. — part lxxvii. — 1888.) Hhkh 33

258 THE VOYAGE OF H.M.S. CHALLENGER.

with an asymmetrical incision, and that the different polymorphous appendages are
attached in regular order to the peripheral convex margin of their discoidal sac. This
margin is divided by a series of equidistant radial constrictions into a number of roundish
polygonal or quadrangular facettes (ten to twenty or more). Each articular facette is
surrounded by a prominent muscular wall or frame, and bears a single large palpon with
its palpacle, and beyond it is attached a single siphon with its tentacle ; in the interval
between them is a pair of gonodendra, a proximal female and a distal male. The cormidia
are, therefore, perfectly ordinate, and succeed one to another regularly in the subhori-
zontal ventral median line of the depressed trunk of the siphosome (compare figs. 9 to 13).
The observations of Sars (already made in 1857) were twenty years afterwards confirmed
and more fully carried out by Claus (in 1878, 74, Taf. iii. figs. 1-4). Moreover,
Gegenbaur had already (in 1859) described in Stephanospira the spiral twisting of the
discoidal inflated trunk, and the regular order in which the siphons and the paired
gonodendra (a male and a female) were attached to the peripheral margin of the spiral
disc ; hence he derived its name. The spiral twisting in the siphosome of all Discola-
bidse seems to be dexiotropic, opposite to the lseotropic spiral of the nectosome ; Claus,
who calls the former also lseotropic, seems to have confounded the proximal and the distal
part of the spiral (74, p. 13).

Cormidia.- — The numerous ordinate cormidia which compose the siphosome of the
Discolabidse, are disposed along the ventral median line of its trunk not less regularly
than in the Apolemidse and the polygastric Calyconectse. The only difference is, that
the naked internodes are in the latter very long, in the former very short ; but they are
sharply marked by the limits of the facettes, or the basal insertions of the single groups
of medusomes. The effective cause of that difference is the divergent development of the
trunk of the siphosome ; this is tubular and much prolonged in a vertical direction in the
Apolemidse, as in the Agalrnidse ; it is vesicular, much shortened and inflated, and coiled
up spirally in a subhorizontal direction in the Discolabidse, as in the Nectalidse. The
trunk of the latter possesses, therefore, permanently about the same shape which the
trunk of the former exhibits only in the state of the strongest contraction.

The composition of the ordinate cormidia is in all the three genera of Discolabidoe
essentially the same. Descending from the proximal or apical (superior and external) face
of the trunk, towards the distal or basal (inferior and internal) face, we find successively
the following parts : — (1) a large palpon with its palpacle; (2) a female gonodendron ;
(3) a male gonodendron ; (4) a large siphon with its tentacle. Sometimes the number of
palpons is doubled, so that a pair of them (a larger superior and a smaller inferior) belong
to each cormidium ; but it seems that this duplication is often accidental, and variable in
one and the same species.

Siphons (PL XX. figs. 13, 16, s). — A single large polypite is attached to the distal side
of each cormidium, and occupies therefore the innermost place on the subhorizontal basal

REPORT ON THE SIPHONOPHOR^E. 259

face of the spirally coiled up trunk. When we regard the latter from below, after the
detachment of the siphons, the remaining pedicles of these form an innermost spiral line
(fig. 12, sp) inside the spiral corona of gonodendra. In Stephanospira these pedicles
were regarded by Gegenbaur as the siphons themselves (10, Taf. xxxii. fig. 53, e). In
spirit specimens of Discolabida; the siphons are usually all detached from their pedicles,
which remain as short conical prominences connected with the trunk (compare 6, pi. iv.
fig. 5). The body proper of the siphon consists of the usual three segments. The
proximal basigaster is very large and occupies in the contracted siphon about its basal
half; its thickened wall is full of small cnidocysts and surrounds a narrow cylindrical
cavity (6, pi. iv. fig. 5). The stomach proper is very dilatable, usually ovate or spindle-
shaped, and exhibits either hepatic ridges, or instead of these numerous glandular villi
developed from its thickened entoderm. The distal proboscis is cylindrical, very con-
tractile, and exhibits usually eight, twelve, or sixteen jtarallel longitudinal muscle-bands ;
it opens distally by a mouth which is very dilatable and may be expanded in the form of
a circular or slightly lobate suctorial disc. Often this distal part is turned over like the
inverted finger of a glove (6, pi. iv. figs. 4-6).

Tentacles (PI. XIX. fig. 1 ; PI. XX. figs. 13, 16, t, 14).— The single tentacle, which
is attached to the pedicle of each siphon, near to the insertion of the basigaster, is in all
Discolabidae very long and beset with a series of very numerous and large tentilla. The
cnidosac of the latter has a peculiar structure, differing from that of all other Siphono-
phorse. The fully-developed tentillum is composed of two segments only, a very large
pedicle and a large involucrate cnidosac ; the third and distal segment, the terminal
filament, has disappeared. The pedicle again is often divided into two portions, a thin
cylindrical proximal tube, and an inflated vesicular distal sac, usually club-shaped or
pyriform. The cnidosac (sacculus or urticating knob) is ovate, spindle-shaped, or
pyriform, bilaterally ysmmetrical, with a more convex dorsal and a less convex or even
concave ventral side ; it contains, included in a double involucre, a very long cnido-
band or urticating chord, coiled up in several spirals. The latter is composed of
innumerable small, paliform cnidocysts, and of two lateral series of large ensiform or
spindle-shaped cnidocysts. These latter are placed at the distal end of the vesicular
cnidosac, whilst they are situated in the other Siphonanthpe usually at its proximal end.

This apparent anomaly, and the divergence in structure from the normal form, is fully
explained by the development of the cnidosac ; it passes during its ontogeny through
different stages, which are represented by the permanent cnidosacs of the genera Circalia,
Stephanomia, Halistemma, and Ayalmopsis. The simple cylindrical tubule of the
youngest tentillum becomes divided into the three usual portions, the pedicle, the
cnidoband, and the terminal filament. The middle one of these is spirally coiled up as a
simple and naked spiral cnidoband. The distal portion of the pedicle becomes inflated,
forms a campanulate fold around the top of this band, and grows around it entirely,

260 THE VOYAGE OF H.M.S. CHALLENGER.

forming a complete external involucre. The canal of the pedicle runs along the
extended and convex dorsal side of the involucre, which overgrows the ventral side.
The axis of the spiral cnidoband, originally vertical, becomes more and more inclined,
is afterwards horizontal and perpendicular to the axis of the pedicle, and finally inverted
completely, so that the original distal end of the cnidoband is situated at the proximal
base of the cnidosac, on its ventral side. The terminal filament, originally the simple
prolongation of that distal end, is early divided into three apophyses, an odd median (the
terminal ampulla) and two paired lateral horns (as in Agalma, &c). But these are not
fully developed (being rudimentary organs) and disappear finally. Tbe basal point of their
original insertion remains visible at the distal end of the reflected cnidoband, near the
proximal base of the cnidosac, in its ventral median line. Compare the full description of
this interesting metamorphosis by Gegenbaur (10, p. 63, Taf. xxx.), Claus (34, pp. 295 et seq.,
Taf. xxvi.), Keferstein and Ehlers (33, p. 10, Taf. iv.), Sars (27, Heft, iii. Taf. v.), &c.

Pa/pons (PI. XIX. fig. 1, q; PI. XX. fig. 16, q). — The large corona of palpons,
which expands at the base of the nectosome and covers the entire siphosome as a
protective roof, is very characteristic of the Discolabidse. The tasters or palpons are in
this family far larger and relatively far more developed than in all the other Siphono-
phorse. They are not only organs of feeling and tasting, but also of capturing and
protecting; they were, therefore, formerly confounded with other organs; Vogt described
them erroneously as bracts (6), and Claus as tentacles (34). Each cormidium possesses
either a single or two palpons, a larger proximal and a smaller distal; and the corona,
therefore, is either simple or double. This difference may perhaps serve also for the
definition of genera, as I have employed it in my System (95, p. 41). Discolabe and
Stephanospira possess a simple corona of tasters, while it is double in Physophora.
But in this latter also usually one corona only (the upper and larger) is fully developed,
and the accessory (lower and smaller) corona is incomplete or rudimentar}*. The
development of the latter is variable in one and the same species (74, p. 15). Each
palpon is a spindle-shaped, cylindrical, or slenderly pyriform tube, with a simple wide
cavity and a very thick muscular wall; the structure of the wall is similar to that of the
trunk ; both the entoderm and exoderm are glandular ; the fulcrum bears inside a plate
of ring-muscles, outside numerous high radial folds which are covered with longitudinal
muscles. The consistence of the fulcral plate is nearly cartilaginous (compare 74, p. 43.
Taf. v. fig. 7). The pointed and closed distal end of the palpon is provided with a
corona of large cnidocysts and tasting cells. The dilated and obliquely truncated
proximal end is apposed by a broad elliptical articular face to the facette of the
siphosome described above, but connected with the latter by a very small pedicle only.
The palpons, therefore, are very easily detached from the siphosome, and a small pore
only in the middle of each articular facette indicates the place of the narrow canal which
connected the wide cavities of the trunk and of the palpon (PL XX. figs. 9-13, cq).

REPORT ON THE SIPHONOPHOR^E. 201

Palpacles (PL XIX, fig. 1, r ; PL XX. fig. 1G, r). — From the upper face of the
proximal base of each palpon arises a very thin tasting filament, usually two or three
times as long as the palpon, but very extensible. It is usually described as an " accessory
tentacle," and represents a narrow cylindrical tubule with a very thin muscular wall,
distinctly articulated, like the antenna of a longicorn insect. The palpacles of the
living Discolabidse, quietly floating at the surface of the sea, are usually in a perpetual
feeling motion, undulating, tasting, and protruding in all directions.

Gonostyles (PL XX. figs. 11—16, q). — The corms of all Discolabidse are monoecious,
and their cormidia monoclinic, each possessing two gonostyles, a male and a female.
These are placed on the peripheral margin of the vesicular spiral trunk, between the
siphon and the palpon of each cormidium, the male (yh) below the female (yf). The
female gonostyle is placed beyond the palpon, richly branched, and forms in the
developed state an ovate bunch composed of many hundred subspherical clustered
gynophores. The male gonostyle (yh) is placed above the siphon, and is very different
in form. It is a single, very large, undivided palpon, with very contractile muscular
wall ; cylindrical in the expanded, slenderly pyriform in the contracted state. It
is often elongated, hangs down like a tentacle, and is densely beset with numerous
oblongish or spindle-shaped androphores arising from short pedicles, either arranged
spirally or scattered irregularly. When the ripe androphores in the distal part of the
gonostyle are detached, their pedicles remain as short knobs or papillae (fig. 16, hp).
(Compare 27, Heft iii. Taf. v. figs. 9-15.) The umbrella of the gonophores is small or
rudimentary. The subspherical manubrium of the gynophores contains a single ovum
only, and is much smaller than the oblongish manubrium of the androphores.

Ontogeny (PL XIX. figs. 5—8). — The larva which arises from the fertilised egg of
the Discolabidse is a Siphonula, the helmet-shaped umbrella of which (b) includes a
pneumatophore (jo) and has a deep ventral cleft. A large spindle-shaped siphon is
suspended in the bilateral cavity of the umbrella or bract, beyond the pneumatophore,
and at its dorsal side a tentacle, the tentilla of which bear each a simple subspherical
cnidal knob, very different from that of the adult Discolabidae. The development of this
medusiform larva from the fertilised eggs of Physophora magnified and its metamor-
phosis were observed by me in February 1867, in the Canary Island Lanzerote, and
described in my Entwickelungsgeschichte der Siphonophoren (84, p. 17, Taf. L— iv.).

The Challenger collection contained some larvae of Discolabidse ver3T similar to these
latter. The most remarkable are figured in PL XIX. figs. 5-8. Fig. 5 represents a very
young Siphonula, the umbrella of which is nearly cap-shaped ; the siphon possesses no
tentacle, but some small buds of tentilla at its base. The larva, fig. 6, somewhat
older, has a large bract with a canal, some buds of palpons, and a long tentacle, beset
with a series of sessile cnidal knobs. These are replaced in the older larva, fig. 7, by
pediculate spherical cnidonodes, or larval tentilla ; the ventral cleft of the bract is much

262 THE VOYAGE OF H.M.S. CHALLENGER.

deeper, the palpons larger ; a pedicular canal (cp) passes from the bracteal canal to the
exumbrella (compare 84, p. 100, Taf. ii. figs. 17—22, y).

The most remarkable larva, however, is the Physonula figured in PL XIX. fig. 8 ;
it was very well preserved in a preparation in the Challenger collection, taken at Station
325, in the South Atlantic (March 2, 1876 ; lat. 36° 44' S., long. 46° 16' W.), in the
tow-net which had been down to a depth of 2650 fathoms. The nectosome was com-
posed of an apical pyriform pneumatophore (p>) and two opposite nectophores (similar
to Dicymba, PL XVIII. fig. 1). The siphosome consisted of a large spindle-shaped
siphon (s), with a simple cylindrical tentacle (t), and a basal corona of about a dozen
slender palpons (q), each provided with a thin and long palpacle (?•). The trunk of
the nectosome in this monogastric larva was apparently the thin pedicle of the siphon
itself (am) ; its apex bore the pneumatophore, as the modified original umbrella of
the primary medusome.

Synopisis of the Genera of Discolabidai.

Nectosome biserial, with two opposite rows of nectophores, . . . .55. Physophora.

Nectosome quadriserial, with four cruciate rows of nectophores, . . . .56. Discolalie.

Nectosome multiserial, with several continuous spiral rows of nectophores, . . 57. Stephanospira.

Genus 55. Physophora,1 Forskal, 1775.

Physopilwra, Forskal, 11, Descript., &c, p. 119.

Definition. — Discolabidse with a biserial nectosome, composed of two opposite rows
of nectophores. (Siphosome with a double corona of palpons.)

The genus Physophora, as one of the oldest known Siphonophorse, was founded in
1775 by Forskal, who distinguished three species of it (11, p. 119). The first of these,
Physophora hydrostatica, has been retained by later authors as the true type of the
genus, whilst the two others belong to different genera, Athorybia (rosacea) and Rhizo-
physa (filiformis). Peron and Lesueur figured, in 1807, an Atlantic species under the
name Physophora myzonema (14, pi. xxix. fig. 4). Quoy and Gaimard published, in 1833,
an incomplete description of four species of Physophora ; they seem to belong to four
different genera (Physophora australis, Discolabe discoidea, Circalia alba, Sphyrophysa
intermedia). Lesson distinguished no less than eight species (3, p. 503). The first
accurate anatomical description of the typical Mediterranean Physophora hydrostatica
w.i.s given in 1853 by Kolliker (4), and Vogt (6), afterwards completed by Leuckart (8),
Huxley (9), Gegenbaur (10), and Claus (34, 74). The ontogeny of Physophora, and its
peculiar metamorphosis, were described by myself in 1869, as observed in a new splendid
Atlantic form, which I called Physophora magnified (84, Taf. i.-v.). A very careful

1 Physophora = Bearing a vesicle, tfvio^o^a..

REPORT ON THE SIPHONOPHOR^E. 2(33

description of a North Atlantic species, Pkysophora borealis, was published in 1877 by
Sara (27, Heft hi. Taf. v., vi.). At present it is not possible to distinguish exactly the
different species of Physophora described by numerous authors ; a far more accurate
anatomical description of the various parts and their arrangement, and a comparison of
good figures drawn from nature, is indispensable to render specific distinction possible.
Since the genus is not rare, and widely distributed over all seas, it is probably repre-
sented by numerous " geographical species."

Genus 56. Discolabe,1 Eschscholtz, 1829 (s. str.).
Discolabe, Esch., System der Acalephen, p. 155.

Definition. — Discolabidae with a quadriserial nectosome, composed of four cruciate
rows of nectophores. (Siphosome with a single corona of palpons.)

The genus Discolabe was established in 1829 by Eschscholtz for a Mediterranean
Physonect, which was described and figured very incompletely by Quoy and Gaimard
under the name Rhizophijsa discoidea (20, Isis, Bd. xxi. Taf. iv. fig. 7). The same
authors called it afterwards Physophora discoidea (2, p. 59, pi. i. figs. 21-24). No doubt
this Mediterranean form represents some Physophorid or Discolabid, the nectophores of
which were detached from the stem ; probably either Physophora hydrostatica (Forskal,
11, p. 119) or Physophora tetrasticha (Philippi, 72). This latter possesses four cruciate
rows of nectophores and differs generically from the former (with two opposite rows of
nectophores). Physophora tetrasticha may, therefore, retain the name Discolabe medi-
terranea, given by Eschscholtz. Another closely allied species, taken in the North
Atlantic (in the Gulf Stream), may be called Discolabe tetrasticha. A third species,
Discolabe quadrigata, inhabits the Indian Ocean, and was observed living by me during
my residence in Belhgemma, in December 1881. It is described in the following pages,
and figured in Pis. XIX. and XX. Some incomplete but well-preserved corms, taken in
the Indian Ocean, which I received from Captain Rabbe (of Bremen), seem to belong to
the same species.

Discolabe quadrigata, n. sp. (Pis. XIX., XX.).

Habitat. — Indian Ocean, Ceylon (Belligemma), December 1881 (Haeckel).

Nectosome (figs. 1-4). — The swimming apparatus has the form of a slender tetragonal
pyramid, which is twice as high as broad; its height is 40 mm., the basal breadth
20 mm. It is composed of an ovate apical pneumatophore, and of four longitudinal rows
of nectophores, which are arranged around the axial trunk in a lseotropic spiral. Each

1 Discolabe = Discoidal noose or spiral, iiaxos, X«/3ij.

264 THE VOYAGE OF H.M.S. CHALLENGER.

row has five or six developed nectopliores, besides some young buds at the apical
blastocrene, below the pneumatophore. Their total number, therefore, is twenty to
twenty-four. Their size increases gradually from the top towards the base of the necto-
some ; the lowermost are the largest. The transverse section of the nectosome, or the
apical view (fig. 15), exhibits a cross composed of four nectopliores, lying in different
horizontal planes according to the spiral twisting of their line of insertion. This lseotropic
spiral line is the ventral median line of the trunk. When the nectophores are detached
from the trunk (figs. 9-13), this latter (an) appears as a spindle-shaped bladder about
four times as long as thick, and tapering towards the two constricted ends ; in its ventral
median line arises a thin membranous vertical lamella, the mesentery of the nectosome,
which bears the contracted pedicles of the detached nectophores (np).

Pneuniatophore (figs. 1, 9-13, p). — The apical float is ovate, 10 mm. long and 5 mm.
broad, with a pink octoradial pigment-star at the top. Eight equidistant meridian lines
connect the two poles of its vertical axis, and are visible outside, as very delicate threads
in the upper, and broad bands in the lower half. These lines are the insertions of eight
meridian ribs on the inside of the pneumatocodon, which connect it in the lower half
with the pneumatosaccus, and so form eight radial pouches. The breadth of the vertical
radial septa separating the latter is effected by eight apophyses of the exodermal
pneumadenia, extending in the fulcrum of the septa, which are covered by entoderm.

Nectophores (figs. 1 and 4, basal view ; fig. 2, lateral view, from the right side ;
fig. 3, dorsal view). — The bilaterally symmetrical umbrella of the largest nectophores is
twice as long and broad as thick ; its principal axis (directed obliquely from above and
inside downwards and outwards) is 12 mm. in length, and the frontal axis the same,
whilst the sagittal axis is only 6 mm. In the median line of the concave ventral side
arises the lamellar pedicle (fig. 2, np), the superior apex of which attaches the nectophore
to the ventral mesentery of the trunk. The ventral edge of this pedicle fits into a
corresponding median groove in the dorsal side of the subjacent nectophore. Seen from
the base (figs. 1, 4), the outline of the nectophore is nearly rectangular, with a deep
furrow in each side. The proximal half of the nectophore is much broader than the
distal half, and ddated in the form of two ovate lateral lobes or auricles (fig. 3). To
these correspond two shorter triangular basal lobes, which arise from the ventral side of
the ostium of the umbrella.

Nectosac (figs. 1-4, w). — The muscular subumbrella of the nectophores is relatively
large, since their jelly umbrella is rather thin- walled ; the form of the latter is determined
originally by the development of the former. The nectosac is composed of three different
parts, which have an irregular ovate form ; an odd median part and two paired lateral
lobes in the proximal half. The nectocalycine duct, which passes through the pedicle
of the umbrella, enters into the ventral side of the nectosac below its top. It divides
into four radial canals of very different shape, two odd sagittal and two paired lateral.

REPORT ON THE SIPHONOPHOR-ffi. 265

The two former run simply curved in the median plane of the nectosac ; the ventral is
shorter than the dorsal. The two symmetrical lateral canals are much longer, each
about three or four times as long as each of the sagittal canals ; they pass into the two
large lateral lobes of the nectophores, where they form half a dozen loops ; their compli-
cated course will be intelligible by comparison of figs. 2, 3, and 4. The small ring-
canal which unites the equidistant distal ends of the four radial canals is elliptical and
lies above the insertion of the velum (fig. 4, cc).

Siphosome (PI. XX. fig. 9, apical view, from above ; fig. 12, basal view, from below ;
figs. 10, 11, 13, ventral and half-lateral view, in different states; all the figures twice
natural size. In PI. XIX. fig. 1, the trunk of the siphosome is completely covered and
hidden by the cormidia). — The trunk of the siphosome is a large reniform bladder, or an
inflated disc of rose colour, subhorizontally expanded and depressed in a vertical direction ;
its breadth (30 mm.) is about twice as great as its height (15 mm.). The wide cavity of
the thin-walled bladder is closed, filled with chyle, or the fluid of the gastrocanal-system,
and communicates only at its apex with the base of the trunk of the nectosome, and by a
peripheral corona of numerous small pores with the cavities of the cormidia. A com-
parison of figs. 9-13 in PI. XX. demonstrates that the kidney-shaped and spirally
twisted disc, from which the name Discolabe is derived, is nothing other than the inflated
trunk of the siphosome twisted up in a low and broad spiral ; the turning of the spiral
is dexiotropic (delta-spiral), opposite to that of the trunk of the nectosome, the necto-
phores of which are arranged laeotropically (lambda-spiral). The trunk of the siphosome
in Physophora is described erroneously as a lambda-spiral by Claus (74, p. 13, Taf. iii.
figs. 1-4). The spiral of the latter is also dexiotropic, but flatter and less developed than
in Discolabe; in the largest specimens of the latter two complete turns may be dis-
tinguished (fig. 12). The superior or proximal face of the discoidal bladder is covered
in the living animal by the base of the nectosome, the inferior or distal face by the axial
parts of the cormidia, whilst the abaxial parts of the latter form a splendid corona around
its peripheral margin.

Cormidia. — The number of ordinate cormidia covering the trunk of the siphosome
is in the smaller specimens of Discolabe ten to twenty, in the larger thirty to fifty or more,
besides the numerous small buds of undeveloped cormidia which arise from the blastocrene
or the point of vegetation situated at the top of the siphosome. Beginning from this point,
the age of the succeeding cormidia increases gradually, so that the lowermost (at the
distal end of the trunk) are the oldest. These, however, are not the largest ; the size of the
cormidia is the greatest in the middle of the spiral series, and decreases towards the two
ends of it. The peripheral margin of the spiral bladder, to which the articulated series
of the ordinate cormidia is attached, is the ventral median line of the trunk of the siphosome.
It appears elegantly facetted and regularly segmented after the detachment of the covering-
corona of palpons ; the size of these polygonal articular facettes, the largest of which are

(ZOOL. CHALL. EXP. PART LXXVII. — 1888.) Hhhh 34

266 THE VOYAGE OF H.M.S. CHALLENGER.

4 to 5 mm. in diameter, decreases also towards the two ends of the spiral, according to that
of the inserted cormidia. Each single cormidium (PI. XX. fig. 16) is composed of the
following parts, which succeed one another in the distal direction, beginning from the
uppermost part of the facette : — (1) a simple palpacle (r) ; (2) a large palpon (2^) ; (3) a
female gonodendron (gf) ; (4) a male gonostyle (gh) ; (5) a tentacle (t) ; and (6) a
siphon (s). Since the tentacle is only an organ of the siphon, and the palpacle an
organ of the palpon, each cormidium may be explained as originally an association of
four medusomes, two fertile and two sterile ; the umbrellas belonging to the latter may have
been originally the nectophores, widely dislocated and separated. The common base of the
trunk from which these parts of each cormidium arise, corresponds to a node or a lateral
branch of those Siphonanthse which have prolonged stems with large internodes and
widely distant ordinate cormidia. The muscular frame which surrounds each polygonal
facette corresponds to the muscle-group of the internode. The facette itself, which
becomes visible after the detachment of the palpons, above the gonodendra, is the base of
their insertion, with the palponal canal in the centre (figs. 9-13, cq).

Siphons (PL XIX. fig. 1 ; PI. XX. figs. 13, 16, s). — The single siphon of each cormidium
is inserted into its distal side or the inferior part of the node of the trunk; this is the inner-
most part in the subhorizon tally coiled-up trunk, on the concave inside of the spiral bladder.
When the siphons are detached from their pedicles, and the trunk seen from below (PI. XX.
fig. 12), the conical papilliform pedicles remaining connected with the trunk form a
regular dexiotropic spiral line on its basal face (fig. 12, sp). The siphon proper, besides
the pedicle, is spindle-shaped or ovate, and has in the dilated state a length of 20 or
30 mm. or more, in the contracted state scarcely 4 to 8 mm. Its basigaster is ovate,
large, the thick-walled exoderm full of small cnidocysts. The dilated stomach is rather
thin-walled, inside covered with vacuolated villi, without coloured hepatic stripes. The
contractile proboscis is very dilatable, with eight strong longitudinal muscle-bands. The
distal mouth may be expanded in the form of a large suctorial disc, and is sometimes
circular, at other times slightly octolobate (figs. 13, 16, so).

Tentacles (PI. XIX. fig. 1; PL XX. figs. 13-16, t).— The long capturing filament,
which arises from the pedicle of each siphon, near the attachment of its basigaster, bears
a series of very numerous large tentilla. Each fully-developed tentillum exhibits the
peculiar well-known structure of Physophora^ and is composed of two parts, a long pedicle,
the distal portion of which is inflated, and a large pyriform cnidosac (fig. 14). This latter
contains, included in a double involucre, a very large, spirally coiled up and reflected pink
cnidoband. The two lateral groups of large ensiform cnidocysts, which were originally
placed on the proximal end of the cnidoband, lie in the fully-developed tentillum
on its distal end ; this remarkable inversion is effected by the peculiar development of
the involucre described above (p. 260). The proximal base of the involucre is con-
nected in the median line of its concave ventral side with the distal end of the reflected

REPORT ON THE SIPHONOPHORJE. 267

cnidoband, and here arc visible in younger tentilla the rudiments of the tripartite terminal
filament. This has disappeared in the adult tentillum (fig. 14). The cnidosac of this latter
is convex on the dorsal, concave on the ventral side, and bearsnear its middle zone a pair
of lateral purple pigment-rings, like ocelli, similar to those which I have described in
Physophora magnified (84, pi. iv. fig. 28). These ocelli (fig. 14, ty), like the similar
ocellar spots of many other animals, are probably protective ornaments discouraging and
frightening the attacking enemies.

Palpons (PI. XIX. fig. 1, q ; PL XX. fig. 16, q). — Immediately beyond the nectosome
is expanded the large corona of palpons, which arises from the top of the siphosome. This
corona is simple in Discolabc (as also in Stephanospira), whilst it is double in Physophora.
Each cormidium bears only a single taster, attached to its uppermost or proximal part.
It is rose coloured, violet towards the apex. The fully-expanded palpon is a thick-walled,
very firm, cylindrical or spindle-shaped tube 30 to 40 mm. in length and 6 to 8 mm.
in breadth ; in the contracted state it is scarcely half as long, and pyriform. The thick
muscular wall is supported by a strong cartilaginous fulcrum and surrounds a wide
cavity, which is closed at the pointed distal end ; this is provided with a corona of twenty
to thirty very large cnidocysts, the protruded cnidofilament of which is more than 1 mm.
in length. The proximal base of the palpon is obliquely truncated and apposed to
the articular facette of the trunk by a very small pedicle. The narrow canal of the
pedicle, which connects the wide cavities of the trunk and the palpon, is visible after the
detachment of the latter as a small pore in the centre of the facette (figs. 9-13, cq).

Palpacles (PI. XIX. fig. 1, r). — Each palpon bears attached to its proximal base, in the
middle of its upper face, a very long and thin tasting filament. It may be extended
to a length which surpasses that of the palpons three or four times or more. The thin
wall of the cylindrical tubule is distinctly segmented, with very numerous equidistant
annular constrictions (PI. XX. fig. 16, r).

Gonostyles (PL XX. figs. 9-16, g). — Each cormidium possesses two gonostyles, arising
from the periphery of the vesicular trunk, one very near to the other, between siphon and
palpon. The female gonostyle is an ovate, richly branched bunch (gf), composed of many
hundred small gynophores. These are subspherical, pediculate, and contain a single ovum
only. The male gonostyle is very different in form, not branched, but a long cylindrical
tube with wide cavity and thin muscular wall, which can be widely extended or strongly
contracted. The surface of this gonopalpon (gq) is covered with numerous oblongish,
spindle-shaped, or subcylindrical androphores, the size and age of which increases from
the proximal towards the tapering distal end. When the ripe androphores in the latter
are detached, their short pedicles remain as small hemispherical papillse. Older gono-
styles bear only a few androphores at their proximal base, while the greater part of the
naked tube hangs down like a papillate tentacle (fig. 16, lip). The ripe androphore is
about four times as long as broad, and much larger than the ripe gynophore.

2G8 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 57. Stephanospira,1 Gegenbaur, 1859.

Stephanospira, Gegenbaur, Neue Beitrage, &c, 10, p. 67, figs. 53-58.

Definition, — Discolabidse with a multiserial nectosome, composed of several rows of
nectophores spirally arranged. (Siphosome with a single corona of palpons.)

The genus Stephanospira was established in 1859 by Gegenbaur for a Physophorid
of unknown origin, of which he could only examine a single incomplete specimen,
preserved in alcohol ; the nectophores as well as the siphons and palpons were detached
and lost ; the trunk only was preserved, with the pneumatophore at the apex and the
corona of gonodendra in the periphery of the siphosome. It is, therefore, easy to explain
that the description of Gegenbaur contained some errors, and that he supposed it to be
a widely aberrant type of Pkysophoridse. Sars has since corrected those errors, and
made it probable that Stephanospira may be only a mutilated specimen of Physo-
phora (27, Heft iii. p. 42). The same opinion is supported by Claus (74, p. 16, &c).
Indeed, it may be that this opinion is right, and in any case Stephanospira belongs to
our family Discolabidse. But the incomplete state of the single specimen examined,
which it is impossible to identify, and mainly the entire absence of nectophores, leaves
open the cpiestion, whether these were arranged originally in two opposite, four cruciate,
or numerous spiral rows. Having recently seen an excellent picture by Mr. Wild, taken
from life, representing an Atlantic Physophora, the conical nectosome of which is
similar to that of Forskalia and composed of numerous nectophores spirally arranged, I
retain for this form the name Stephanospira. I shall publish the description and figures
of this Stephanospira corona in my Morphology of the Siphonophorse. In form the
vesicular spiral trunk and the distinctly ordinate monoclinic pairs of gonodendra are
similar to those of Step>hanospira insignia, Gegenbaur.

Family XVII. Anthophysid^e, Brandt, 1835.

Anthophymlx, Brandt, 1835, Prodromus, &c, 25, p. 35.
Athorybidx, Huxley, 1859, 9, pp. 71, 85.

Definition. — Physonectse polygastricse, with a short vesicular stem of the siphosome,
bearing numerous siphons and palpons, each siphon provided with a branched tentacle.
Nectosome without nectophores, but with a corona of bracts. Pneumatophore with
radial pouches.

The family Anthophysidse of Brandt (1835), identical with the Athorybidse of
Huxley (1859), differs from all the other Physonectse polygastricse in the absence
of nectophores, which are replaced by a corona of bracts. It agrees in this striking

1 Stephanospira — Spiral corona, mttauo;, ont^x.

REPORT ON THE SIPHONOPHORJE. 269

character with the monogastric Athoridae, but differs from this closely allied family in
the possession of numerous siphons.

The first described and the best known type of Anthophysidae is the Mediterranean
Athorybia rosacea. It was discovered by Forskal, who figured it under the name
Physophora rosacea as early as 1775 (11, Tab. xliii. fig. B). Two other olosely
related species, taken in the Strait of Gibraltar, were described by Quoy and Gaimard
as Rhizophysa heliantha and Rhizophysa melo (20), and afterwards jjlaced by the same
authors in the genus Stephanomia (2). These three species together were united in
the genus Athorybia by Eschscholtz (l, p. 153) in 1829. A similar fourth form,
taken in the Northern Pacific, was described by Mertens as Anthoplxysa rosea (25,
p. 36), and Brandt in 1835 established for all these together the family Anthophysidae.

The first accurate anatomical description of Athorybia was published in 1853 by
Kolliker (4, Taf. vii.), and supplemented by Huxley in 1859 (9, pi. ix.). He called
the family represented by it Atkorybidae. The genus Anthophysa differs from the
former in the possession of two kinds of tentacular knobs. An American species of
this genus was afterwards accurately described by Fewkes, under the name Athorybia
formosa (44, p. 271, pis. v., vi.). The development of the fertilised egg was examined
in 1866 by myself (84, p. 88, Taf. xiv.).

The Anthophysidae, or Athorybidae, are among the most beautiful and most delicate
Siphonophorae. But they are in general rare, and owing to their small size and
fragility their anatomical investigation is difficult. Some interesting new forms of this
family, which I was able to examine living in the Mediterranean, the Atlantic, and the
Indian Ocean, have enabled me to complete their anatomical knowledge (Pis. XL, XII.).

Truncus. — The coenosome or common stem is in all Anthophysidae a small ovate,
pyriform, or flatly conical vesicle. Its apical (proximal or superior) half is the necto-
style, includes the pneumatocyst, and bears the corona of bracts ; its basal (distal or
inferior) half is the siphostyle, and bears in the periphery a corona of very numerous
palpons, in the central part a smaller number of siphons, tentacles, and gonostyles.

Although the general appearance of the eorm in all Anthophj^sidae is radial,
nevertheless the fundamental form of the trunk is always bilateral, as in all the other
Siphonanthae. The series of buds, which is visible as well in the nectosome (PI. XII.
fig. 9, ib) as in the siphosome (fig. 9, is), marks the ventral median line of the trunk.

Cormidia. — The numerous polymorphous persons or medusomes, which compose
the corm of the Anthophysidae, are arranged around the common central trunk in a
certain regular manner. This has hitherto escaped all observers, owing to the small
size and the great delicacy of the object. The specimen of Anthophysa darwinii,
which I found in the Challenger collection, and which is figured in PI. XII. figs. 7-9,
exhibited this regular arrangement of the cormidia more distinctly than the smaller
species of Athorybia hitherto described. In general this ordinate structure seems to be

270 THE VOYAGE OF H.M.S. CHALLENGER.

similar to that of Physophora and the other Discolabidse, the cormidia being ordinate
and arranged symmetrically in a flat spiral line, which is twisted around the flat and
broad base of the shortened vesicular stem. (Compare PI. XII. figs. 7-9 ; fig. 7, dorsal
view ; fig. 8, lateral view, from the left side ; fig. 9, ventral view.)

The ventral view (fig. 9) exhibits at once the bilateral form of the corm, which is
bisected in the ventral median line by the series of buds ; these develop from two
separate blastocrenes (springs of buds, or " puncta vegetationis "). The superior
blastocrene (ib) is the point of development of the nectosome (bracts), and from it
radiate bilaterally the ridges which bear the pedicles of the bracts. Each convex ridge
is composed of four finer parallel ribs ; these are straight and horizontal in the uppermost
and oldest ridges, undulating and vertical in the youngest and lowermost ridges. There
are five or six quadripartite ridges on each side of the trunk of the nectosome, divergent
from the ventral towards the dorsal side, where the large ovate pneumatophore arises.
The inferior blastocrene (fig. 9, is) is the punctum vegetationis of the siphosome ;
its numerous buds, densely crowded in the lower half of the ventral median line,
become so developed and dislocated that the superior compose a corona of palpons (q),
the inferior a basal corona of gonostyles (g) and alternating siphons (s) and tentacles (t).
The arrangement of these parts in the lateral view of the corm, after removal of the
majority of the palpons (fig. 8), seems to demonstrate that the cormidia, although densely
crowded without interval, are nevertheless ordinate. Each cormidium seems to be
composed of a large siphon, and the appertaining tentacle, of two gonodendra (a male
and a female group of gonophores), and of a certain number of palpons. Further, each
cormidium of the siphosome seems to belong to a corresponding quadripartite ridge of
the nectosome, with four parallel ribs bearing a number of bracts (figs. 8, 9, bp).

Respecting the phylogenetic origin and development of this peculiar arrangement,
we may assume that originally each ridge of the nectosome (with a group of bracts), and
each cormidium of the siphosome, have arisen from a single medusome, the former from
its umbrella, the latter from its manubrium ; both being widely dislocated afterwards.
But in these ordinate cormidia of the Anthophysidse, as well as in the similar ones of
the Discolabidae and Nectalidse, a further comparative morphological study is required
to solve the difficult question of their original composition.

Pneumatophore. — The float filled with air occupies the upper half of the ccenosome,
and is usually ovate or ellipsoidal. Its uppermost part is sometimes prominent over the
corona of bracts, at other times retracted and hidden between them. Its apex usually
bears a pink or purple pigment-star with eight rays, composed of elegant polygonal
exoderm cells (figs. 5-9). The centre of this star is usually colourless. The pneumato-
saccus includes the thin-walled chitinous pneumatocyst. Its lower part is connected
by a variable number of radial septa (usually eight or sixteen) with the pneumatocodon or
the outer wall of the float (fig. 7, p).

REPORT ON THE SIPHONOPHOR^E. 271

Bracts (PL XL figs. 1, 2; PL XII. figs. 14-16).— The liydrophyllia, or bracts, which
make up the main part of the nectosome, form an elegant corona around the pneumato-
phore, similar to a double rose, or other flower with numerous petals. Their number is
usually between twenty and forty, sometimes more than sixty. They are always thick
sickle-shaped scales of a more or less elliptical or lanceolate outline, strongly curved, and
attached to the stem by a short pedicle. Sometimes these pedicles are rather broad
lamella?, similar to the pedicles of the nectophores in the Rhodalidas (PI. XII. figs. 7-9, bp).
The inner or axial face of the bract is concave and smooth, the outer or abaxial face
convex and armed with a variable number of longitudinal ribs or crests, which bear a
series of cnidocysts. The thick and firm jelly-substance of the cartilaginous bract
encloses a simple canal or phyllocyst, which runs near the inner surface in the median
line, and ends blindly at the distal end (fig. 14, be).

No doubt the bracts of the Anthophysidaa are either parts of divided nectophores, or
entire reduced nectophores which have lost the nectosac with the subumbrella and the
four radial canals, but developed more strongly the jelly-substance of the umbrella,
forming a firm protecting scale, or a " cartilaginous shield." The bracts of Rhodophysa
still possess a small rudimentary nectosac at the distal end, similar to that of Athoria,
and of the Athorula larvae of many Physonectse (PL XXI. figs. 5-12). The arrange-
ment of the bracts in a simple corona, or in several concentric closely apposed circles
(one over the other), is very similar to that exhibited by the simple or multiple corona
of nectophores in the Rhodalidse (Auronectae). As in these latter, the apparent radial
arrangement is at the same time bilateral, since the series of buds in the median
ventral line (PL XII. figs. 7-9, ib) bisects the corona into two symmetrical halves. The
corona of bracts in Anthophysa (PL XII. fig. 7, from the dorsal; fig. 8, from the left;
fig. 9, from the ventral side) is distinguished by the peculiar bilateral arrangement of
the arched ribs of the nectosome, which bear the pedicles of bracts (bp). Each ridge is
composed of four parallel finer ribs ; therefore four bracts are associated in a smaller group.
This quadripartite structure may be perhajDS explained by the supposition, that each bract
is originally the quadrant of a quadripartite umbrella ; the more so as the number of bracts
is about four times as great as the number of siphons (the dislocated manubria ?).

The bracts are organs of protection as well as of locomotion. They cannot change
their form ; but they can be elevated and depressed by means of a pedicular muscle,
which is attached to their basal pedicle. When freely swimming at the surface of the
tranquil sea, the corona of bracts is alternately closed and opened by slowly elevating and
depressing the single bracts ; the water protruded from the cavity surrounded by the
bracteal corona (and comparable physiologically to the swimming cavity of Medusas) pro-
pels the body in the apical direction, the pneumatophore forwards. But when the animal
is alarmed the bracts are contracted closely together and surround a subspherical, nearly
closed cavity, in which the retracted palpons, siphons, tentacles, and gonodendra are hidden.

272 THE VOYAGE OE H.M.S. CHALLENGER.

Palpons (PI. XI. figs. l,q, 2, 4; PI. XII. figs. 7-9, q).— The tasters of the Antho-
physidfe form a simple or multiple corona beyond that of the bracts ; their number is
very large but variable, and seems to correspond usually to that of the latter ; it is pos-
sible that originally one taster belonged to each single bract, both together composing a
medusome (?). The palpon in this case would be the manubrium, and the bract the
appertaining umbrella of the medusome. The arrangement of the tasters, too, in the
larger Anthophysidse, is very similar to that of the bracts, and the corona of both is
bisected by the series of buds (fig. 9, is) placed in the median line of the ventral side.

The tasters are very long and thin, cylindrical or spindle-shaped tubules, widely
jjrotruding through the spaces left between the adjacent bracts when the latter are
expanded (PI. XL fig. 1). They are very mobile and flexible, tasting like feelers on all
sides. The proximal end of their simple cavity opens into the common stem-cavity,
whilst the distal end is closed, and usually armed with a corona of large radial cnidocysts
(fig. 4, qc). Sometimes a pigment-spot is visible at the lower side of the distal end, and
in Atliorybia ocellata this eye-spot seems to surround a small lens or refracting body ; it
may be perhaps an ocellus (fig. 4, qo). When contracted, the palpons appear as spindle-
shaped or ovate vesicles, hidden in the cavity surrounded by the corona of bracts. There
are no palpacles or tasting filaments at the base of the palpons.

Siphons (PI. XL figs. 1, s, 3 ; PI. XII. figs. 7-9, s, fig. 10, longitudinal section). —
The number of polypites or siphons in the Anthophysidse is always much smaller than
that of the palpons and bracts ; usually the number of the latter may be four to six
times as great as that of the former. The smaller species of Anthophysidse have usually
only three to six, the larger eight to twelve siphons. These occupy the basal part of the
trunk, beyond and inside the corona of palpons, which are much smaller in size. The
usual four segments in the body of the siphon are very distinct (figs. 3, 10, longitudinal
section). The short pedicle (sp) opens by a narrow canal into the cavity of the trunk.
The basigaster (sb) is very large and thick-walled, usually of a yellowish or reddish
colour ; the exoderm is much thickened and filled with innumerable cnidocysts. The true
stomach (sm) is ellipsoidal, ovate or subspherical, and has a thin exoderm; but the ento-
derm-wall is very thick and protrudes inside in the form of numerous conical villi, which
contain a variable number of vacuoles or glandular spaces (fig. 10, sv). The proboscis
(sr) is very large and extensile; in the contracted state (fig. 10, sr), its muscular wall
is very thick, and the entoderm composed of high cylindrical epithelial cells ; sometimes
six or eight longitudinal ribs are visible (fig. 3, sr). The terminal mouth may be ex-
panded in form of a large, delicate, polygonal suctorial disc, usually with six or eight
triangular lobes (fig. 1 , ss).

Tentacles (PI. XL fig. 1; PI. XII. figs. 11-13).— Each siphon is provided at its base
with a long tubular tentacle, which bears a series of tentilla or lateral branches. The
form and composition of these tentilla exhibits in the different genera of Anthophysidse

REPORT ON THE SIPHONOPHOR^E.

273

differences similar to those in the Agalmidse. The cnidonode of the tentillum includes
a spiral band with a few turnings ; the cnidobattery of this band is composed of very
numerous small median cnidocysts and two opposite lateral rows of large spindle -shaped
cnidocysts. It bears a simple terminal filament in the two genera Rhodophysa and Melo-
physa, whilst it is trifid in the two genera Athorybia and Anthophysa, divided into a
median terminal vesicle and two paired lateral horns ; usually these are coiled up spirally
(PI. XII. figs. 11-13). The distal part of the cnidonode is prolonged commonly on the
dorsal side into a conical apophysis or a solid pointed spur, composed of large hyaline
entoderm cells. Besides, the genus Anthophysa is distinguished by the possession of
a second, larger and rarer, kind of cnidonode, differing from the former in the develop-
ment of two paired, dendritic or palmate apophyses on the dorsal side of the cnidosac.

Gonostyles. — Each cormidium of the siphosome (probably in all Anthophysidse) is
monoclinic and bears two gonodendra, a male and a female, attached to the base of the trunk,
near to the insertion of the appertaiuing siphon. Sometimes the two branched gonostyles
arise separately, each with a proper pedicle (PL XII. fig. 17, gp, male ; fig. 18, gp, female) ;
at other times both arise from a common pedicle, which also bears some small palpons
or sexual hydrocysts (9, pi. ix. fig. 12). The gonophores arise clustered in variable
number from the branches of the dendritic gonostyles ; the males are usually coloured
(reddish or white), the females colourless.

The androphores, or the male medusiform gonophores (fig. 17, h), have an oblong,
club-shaped or even cylindrical umbrella, the narrow distal mouth of which is surrounded
by a small velum ; above this lies a small circular canal, which unites the four radial
canals. The spermarium (lis) is a long spindle-shaped or cylindrical manubrium, with a
central spadix (hx) ; it fills up the subumbrellar cavity and is often protruded from it.

The gynophores, or the female medusoid gonophores (fig. 18,/), develop only a single
large ovule in the wall of the manubrium, and the central canal of the latter, growing
around the surface of the ovule, and partly obliterating, forms a network of irregular,
spadicine canals, not to be confounded with the four radial canals of the embracing
umbrella.

Synopsis of the Genera of Anihophysidse.

Tentilla with a simple (naked or involucrate)
cnidoband and a single terminal filament.

Tentilla with an involucrate cnidoband and
three to five terminal appendages. Bracts
without nectosac.

Bracts with a rudimentary nectosac at the

distal end. Cnidoband naked, . 58. Rhodophysa.

Bracts without nectosac.
volucrate,

Cnidoband in-

All tentilla of the same form, tricornuate.
Cnidosac without dendritic apophyses, .

Tentilla tricornuate, of two different forms ;
the larger with two dendritic apophyses

of the cnidosac,

(ZOOL. CHALL. EXP. — PART LXXVII. 1888.)

59. Melojihysa.

60. Athoryhia.

61. Anthophysa.
lllihh 35

274 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 58. Rhodophysa,1 Blainville, 1834.
Rhodophysa, Blainville, Actinologie, p. 123 (sensu mutato).

Definition. — Anthophysidse with a rudimentary nectosac at the distal end of the
bracts. Cnidonodes of the tentacles simple, without involucre, with a naked cnidoband
and a single terminal filament.

The genus Rhodophysa was constituted by Blainville (24) for the reception of the
same three forms of Physonectse which Eschscholtz had united five years before in his
genus Athorybia. This latter name therefore has the right of priority. Retaining here
the name Rhodophysa, I employ it for those interesting, hitherto undescribed, forms of
Athorybidse, which differ from the others in the possession of a small rudimentary nectosac
at the distal end of the bracts. This structure is the same as is found in Athoria amon^
the monogastric Athoridse (p. 201, PL XXI. figs. 5-10), and in the similar Athorula-
larvse of some Physonectse (p. 200). It is of great morphological interest, as a proof
that the bracts in this case are reduced nectophores.

A single specimen of Rhodophysa was observed by me in the Indian Ocean during
my voyage from Ceylon to Aden (between the Maldive Islands and Socotra) in March
1882. It was in general very similar to the well-known Mediterranean Athorybia rosacea,
being also of the same light rose-colour, but differed in two essential points. Each bract
exhibited at the distal end a small rudiment of a nectosac, similar to that of Athoria
larvalis (PL XXI. figs. 5-10). Further, the tentilla possessed a naked spiral cnidotsenia,
with a single terminal filament, similar to the tentilla of Athoria and Forskalia
(PL X. fig. 23). Unfortunately the single specimen of this remarkable Rhodophysa
corona was destroyed before I could make a representation of it. It requires further
examination.

Genus 59. Melophysa,2 Haeckel, 1888.
Melophysa, Hkl., System der Siphonophoren, p. 42.

Definition. — Anthophysidse with simple bracts, without nectosac. Cnidonodes of the
tentacles simple, with an involucre and a single terminal filament.

The genus Melophysa comprises those Anthophysidse which have the general structure
of the typical Athorybia, but differ from it in the singular form of the tentilla, or the
cnidal knobs of the tentacles. Each tentillum bears a simple spiral cnidotsenia, the basal
half of which is enveloped by an involucre, and at its distal end a simple terminal
filament ; it is therefore similar to the tentilla of Stephanomia (9, pi. vi. fig. 8).
Respecting this difference, Melophysa exhibits a relation to Athorybia similar to
that which Stephanomia bears to Crystallodes, or Halistemma to Agalmopsis.

1 Rhodophysa = Rose-bladder, polo*, q>vou. 2 Md )physa = Melon -vesicle, fifaov, quax.

KEPORT ON THE SIPHONOPHORiE. 275

During my residence in the Straits of Gibraltar, in March 1867, 1 once encountered a
small elegant Anthophysid, which at first glance I supposed to be a species of Athorybia.
A closer examination, however, demonstrated that the form of the tentilla was quite
different, each spiral cnidotaenia being half enveloped by a campanulate involucre and
ending with a single terminal filament (as in Anthemodes, PI. XV.). The form of
the bracts was very similar to that figured in Athorybia melo, which Quoy and Gaimard
had observed in the Strait of Gibraltar forty years before (2, pi. ii. figs. 7-12). It is
possible that these two forms are identical. The single specimen of Melophysa melo
captured was lost before I could make a drawing of it.

Genus 60. Athorybia,1 Eschscholtz, 1829.
Athorybia, Esch., System der Acalephen, p. 153.

Definition. — Authophysidse with simple bracts, without nectosac. Cnidonodes of
the tentacles involucrate, trifid, with a median terminal vesicle and two lateral horns.

The genus Athorybia, the oldest and best known form of Anthophysidse, was founded
by Eschscholtz for the reception of three closely allied species ; the typical Mediter-
ranean form described in 1775 by Forskal (11) as Physophora rosacea, and two species
observed in the Strait of Gibraltar by Quoy and Gaimard, and named Rhizophysa
heliantha and Rhizophysa melo (20). An accurate anatomical description of the
Mediterranean Athorybia rosacea was first given in 1853 by Kolliker (4, p. 24, Taf. vii.).
Athorybia heliantha from the Northern Atlantic seems to be closely allied to it; it
differs, however, in the special form of the tentilla described by Gegenbaur (10, p. 82,
Taf. xxxi. figs. 43, 44). ■ Another form of tentilla is exhibited in the Canarian
Athorybia ocellata described in the sequel, differing also from the former species
the form of the bracts and the possession of ocelli on the palpons. Another species,
distinguished by the form of the bracts as well as that of the cnidosacs, is Athorybia
indica, discovered by Huxley in the Indian Ocean and described under the name
Athorybia rosacea (9, p. 86, pi. ix.). The gonodendra of this species are monostylic,
while usually they are distylic. A number of different species of this genus seem to
inhabit all warmer seas ; they are, however, in general rare, and an accurate description
illustrated by figures taken from the living animals is required to render their com-
parison and specific distinction possible. Special attention must be paid to the bilateral
structure of the vesicular trunk, its ventral series of buds (PI. XII. fig. 9, ib, is), and the
relation of the nectostyle to the siphostyle. In some species of Athorybia the retracted
pneumatophore is covered on its ventral side by the prominent cucullate nectostyle,
as in Anthophysa (PI. XII. figs. 7-9).

1 Athorybia = Pacific, aSotfific;.

•27(3 THE VOYAGE OF H.M.S. CHALLENGER.

Athorybia ocellata, n. sp. (PI. XL ; PI. XII. figs. 10^-18).

Habitat. — North Atlantic, Canary Islands (Lanzerote); January and February
1867 (Haeckel).

Corm (PI. XL fig. 1, lateral view; fig. 2, apical view). — The complete body of
the elegant corm is in the contracted state, with retracted organs, nearly spherical,
10 to 12 mm. in diameter. In the expanded state, with distant bracts and elongated
organs, it has the appearance of a rose or other double flower. The numerous palpons
are then protruded between the distant bracts, and the siphons and tentacles more or
less prominent. The colour of the entire corm is slightly roseate, the bracts somewhat
bluish, the float purple, the centre yellow.

Truncus.— The common central stem is an ovate or slightly conical vesicle, 6 to 9
mm. in diameter. Its upper pointed part is the nectostyle, includes the pneumatocyst,
and is surrounded by the corona of bracts. Its broader lower part is the siphostyle,
and bears a corona of numerous slender palpons, and beyond these, in the central part
of the base, four to eight large siphons, each provided with a tentacle and surrounded
by two gonodendra, a male and a female. The conical top of the nectostyle (PI. XL
fig. 1, ib) embraces sometimes the ventral side of the retracted pneumatophore (p) like a
cowl, and the apex of the former is prominent over that of the latter.

Pneumatophore (figs. l,p, and 5, lateral view; figs. 2 and 6, apical view). — The
pneuniatosaccus, which is formed by the invaginated upper half of the conical necto-
style, includes an ovate or urn-shaped pneumatocyst (figs. 5, 6). Its apex is colourless,
surrounded by a pigment-star with eight pink lanceolate rays. Its basal part exhibits
eight radial pouches, separated by eight vertical septa of the pneumatophore. The
retracted float may be hidden completely between the bracts.

Bracts (PL XL figs. 1,2; PI. XII. figs. 14-16).— The bracts or covering scales, thirty
to fifty in number, form an elegant corona around the pneumatophore. They are arranged
in three or four circles, closely placed one over the other ; these circles may be regarded
as parts of a symmetrical corona, bisected by the ventral series of buds. The bracts are
elliptical or lanceolate, 6 to 9 mm. long, 2 to 3 mm. broad, inside concave and smooth,
outside convex and armed with a variable number of cnidal crests, usually eight. The
exodermal epithelium of the outside is composed of large polygonal cells, and includes
near the lateral margin a number of scattered large cnidocysts (fig. 15, h), and at the
margin itself, as well as in the prominent ribs (fig. 16, br), patches of cnidocysts and dark
pigment-granules. The simple canal of the bract runs along the median line of the inner
concave face (fig. 14, be), and ends blindly near to its apex. The jelly-substance of the
bract is rather thick and firm.

REPORT ON THE SIPHONOPHOR^E. 277

Palpons (figs. 1, q, 2, 4). — The tasters are long and thin cylindrical, rose-coloured
tubules ; they seem to correspond in number and arrangement to the bracts, and are
attached in a corona beyond the latter. When the corona of bracts is expanded (figs. 1,
2), the feelers are widely protruded through the clefts between them, tasting on all sides.
The simple cavity of the thin-walled muscular palpons opens into the common stem cavity
at the proximal end, whilst their distal end is closed and surrounded by a ring composed
of larger thread-cells (fig. 4, qe). Somewhat above this ring is a pink pigment-spot placed
at the lower side of the palpon ; it may be regarded as an ocellus, since it is provided with
a roundish refracting body, similar to a lens (fig. 4, qo).

Siphons (PI. XI. figs. 1,5, 3; PI. XII. fig. 10, longitudinal section). — The number
of polypites is small, and did not exceed eight in the largest specimens observed ; the
smaller had only four or five. Their size is large ; their colour rose. Their base is
attached to the common stem beyond the corona of palpons. The short pedicle of each
siphon (sp) bears a thick-walled basigaster (sb), the exoderm of which has a golden
yellow colour and contains crowded masses of cnidocysts. The stomach (sm) exhibits
inside numerous conical villi containing glandular bodies and vacuoles. The entoderm of
the extensile proboscis is composed of high and slender cylindrical cells (fig. 10, sr). The
distal mouth may be expanded in the form of a broad and delicate suctorial disc, which
is sometimes distinctly polygonal, with six or eight short lobes (PI. XL fig. 1, ss).

Tentacles (PL XI. fig. 1). — To the pedicle of each siphon, close to its base, is
attached a long tubular tentacle which bears a series of very numerous tentilla or lateral
branches. Each tenrillum (PI. XII. fig. 11, from the ventral; fig. 12, from the dorsal;
fig. 13, from the lateral, left side) bears upon a long pedicle (ts) an ovate cnidosac. The
large cnidobattery contained in it has one and a half or two spiral turnings and is
composed of innumerable small paliform cnidocysts, with a lateral row of large ensiform
cnidocysts (tk) on each side. From the distal end of the cnidosac arise four terminal
appendages, two odd sagittal and two paired lateral. The latter are two cylindrical
filaments, usually coiled up spirally, like two frontal horns (tc). Between these arises
from the ventral side an ovate thin-walled vesicle or terminal ampulla {to), and opposite
to this from the dorsal side a conical solid spur, composed of large clear entoderm-
cells (tz).

Gonophores. — Each cormidium is monoclinic, and bears on separate stalks, attached to
the trunk of the siphosome close to the base of the siphon, two gonodendra composed of
clustered gonophores, a male (fig. 17) and a female (fig. 18). The male gonophores (h)
are rose-coloured and more oblong, with a club-shaped spermarium (hs). The female
gonophores (/) develop only a single egg in the manubrium. The umbrella has in both
sexes four radial canals and a marginal ring-canal.

278 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 61. Anthophysa? Mertens, 1829.
Anthophysa, Mertens, MS. (Russian Acad.) ; Brandt, Prodromus, &c, 1835, 25, p. 35.

Definition. — Anthophysidse with simple bracts, without nectosac. Cnidonodes of
the tentacles involucrate, trifid, with a median terminal vesicle and two lateral horns ;
besides a part of the cnidonodes larger, with two dorsal dendritic apophyses.

The genus Anthophysa was established by Mertens in 1829 for a large and very
interesting Anthophysid, which he observed living (May 12, 1828) in the Northern
Pacific, north of the Bonin Islands (lat. 36° 30' N., long. 214° 0' W.). Brandt afterwards
(in 1835) gave a short description of it (25, p. 35), and founded upon this genus and the
closely allied Athorybia of Eschscholtz the family Anthophysidae. The excellent figures
of it executed by Mertens were never published, but I have examined them and compared
them with his manuscript. According to this, the vesicular truncus is pyriform and
rather large, similar to a small Alophota or a young Physalia, about two inches in
diameter (30 mm. long and 20 mm. high). The purple pneumatophore is surrounded by
a corona of numerous sickle-shaped bracts ; and beyond these twelve siphons are visible,
each provided with a long articulate tentacle.

The structure of the tentacles in this Anthophysa rosea (Mertens) seems to be similar
to that of a North Atlantic species which Fewkes described in 1882 under the name
Athorybia formosa.2 This beautiful species differs from the true Athorybia in the
possession of two kinds of cnidosacs on the tentacles, one of which is similar to that of
the latter, the other distinguished by the addition of two dorsal dendritic apophyses.3

A third species of Anthophysa, which seems to be closely allied to the two preceding,
was found by me in a bottle in the Challenger collection (from Station 334, South
Atlantic), and although the only specimen was incomplete and not very well preserved,
I will give its description in the following paragraphs.

Anthophysa darioinii, n. sp. (PI. XII. figs. 7-9).

Habitat— Southern Atlantic; Station 334, March 14, 1876; lat. 35° 45' S., long.
18° 31'W.; surface.

Corm (PI. XII. fig. 7, dorsal view ; fig. 8, lateral view from left side ; fig. 9, ventral
view). — The complete body of the corm in the spirit specimen which I examined and
figured was well preserved, although strongly contracted by the influence of the alcohol.
All the parts of the single organs were present, with the exception of the bracts, the
majority of which were detached, a few only remaining (fig. 9, b). The entire corm had

1 Anthophysa = Flower-shaped bladder, avOo;, tpvua.

"- Bull. Mus. Comp. Zool, vol. ix. No. 7, p. 271, pi. v. figs. 3, 4 ; pi. vi. figs. 7-1-1.

3 Loc. cit., pi. vi. figs. 7, 8.

REPORT ON THE SIPHONOPHORJE. 279

on the whole a flat conical form and a diameter of 10 mm. to 15 mm. The upper smaller
half (in the lateral view, fig. 8) is the nectosome, composed of the pneumatophore and
the corona of bracts. The lower larger half is the siphosome, with the palpons, siphons,
tentacles, and gonostyles.

Nectosome. — The superior half of the flatly conical corm is the nectosome, composed
of a large pneumatophore (p) and of a corona of numerous bracts. These latter were
nearly all detached and lost, except a few (fig. 9, b) ; but the lamellar pedicles of
the bracts and the basal ribs of their attachment to the nectosome (bp) were well
preserved, and exhibited the peculiar arrangement described above (p. 271). The
bilateral conical nectosome is bisected by the series of buds in the ventral median line.
The uppermost part of the nectostyle is prominent over the ventral side of the
pneumatophore and bears a cluster of very young buds (ib). From this blastocrene
(or the punctum vegetationis of the nectophores) diverge five or six pairs of radial
ridges, each of which is composed of four fine parallel ribs, bearing the pedicles of the
bracts. The youngest ribs are undulating, and placed on both sides of the ventral
median line vertically (fig. 9) ; the oldest ribs are straight, and run nearly horizontally
and perpendicular to the former, embracing the upper half of the pneumatophore like a
cowl.

Pneumatophore (figs. 7-9, p). — The float is an ovate vesicle, which occupies the upper
half of the conical trunk. Its dorsal side (fig. 7,p) is free and exhibits above the pigment-
star of the apex, below a corona of sixteen radial stripes (probably radial septa between
the pouches of the pneumatosac). The ventral side (fig. 9,p) and the greater part of the
lateral sides (fig. 8) are covered by the embracing cucullate nectostyle and by the corona
of bracts attached to it. (Compare above.)

Bracts (fig. 9, b). — The bracts of this species are probably very numerous and attached
to the trunk of the nectosome in the peculiar order described above (p. 271). But
nearly all the bracts were detached and lost in the only observed spirit specimen. A
few only were preserved (fig. 9, b), and these were oblong or lanceolate leaves, with a basal
pair of lateral teeth beyond their lamellar pedicle. The concave inner or axial side of
the bract is smooth, the convex outer or abaxial side armed with a number of parallel
cnidal ribs (six to eight ?).

Siphosome. — The inferior half of the conical corm is the siphosome, composed of a
superior corona of very numerous palpons (q) and an inferior corona of cormidia, each of
which bears a siphon (s), a tentacle (t), a male and a female gonodendron (g). The
peculiar arrangement of these ordinate cormidia and their relation to the quadripartite
groups of bracts has been described above (p. 271). The full number of cormidia in the
specimen observed was probably ten or twelve, the youngest and smallest placed in the
ventral median line, the oldest and largest in the dorsal median line (fig. 8, lateral view,
from the left side). The blastocrene of the bilateral siphosome, or the series of buds in

280 THE VOYAGE OF H.M.S. CHALLENGER.

its ventral median line (fig. 9, is), bisected it so regularly that the cormidia were ordinate
symmetrically right and left.

Siphons (figs. 7-9, s). — The size of the polypites, according to the ordinate bilateral
arrangement just mentioned, increases from the ventral towards the dorsal side (fig. 8, s)-
They were ovate thick- walled sacs, strongly contracted in the only spirit specimen observed.
The structure of the siphons is probably the same as in Athorybia (PI. XII. fig. 10).

Tentacles. — The greatest part of the tentacles were detached and lost in the spirit
specimen observed; a few fragments only remained. The tentilla were of two kinds, and
apparently both of the same form as described and figured by Fewkes in his Athorybia
formosa (loc. cit., p. 274, pi. vi. figs. 7-10). The smaller and more frequent form of
cnidosacs is similar to that figured in Athorybia ocellata (PI. XII. figs. 11-13). The
larger and rarer form exhibits besides two large dorsal dendritic appendages, which
were dichotomously branched, of the same shape as in Anthophysa formosa (Fewkes, loc.
cit., fig. 7, lateral view, from the right side, fig. 8, basal view).

Palpons (figs. 7-9, g). — The tasters were very large and numerous in the specimen
observed, and composed a multiple corona beyond the corona of bracts. Their form is
slender, spindle-shaped, tapering towards the attached basal and the closed distal ends.

Gonophores (g). — Close to the base of each siphon are attached to the siphosome two
small branched gonodendra, a male and a female. Their structure is similar to that of
Athorybia (PL XII.), the spermaria (fig. 17) as well as the ovaria (fig. 18).

LATER ADDITION TO THE ANTHOPHYSHLE.

Plceophysa agassizii, Fewkes.

Plixophysa agassizii, Fewkes, Ann. and Mag. Nat. Hist., ser. 6, vol. i. pp. 317-322, pi. xvii.,

1888.

While correcting the proof of this sheet, I have received a paper by Mr. J. Walter
Fewkes, published in May 1888 (loc. cit.), and entitled : On a New Physophore, Plceophysa,
and its Relationships to other Siphonophores. A comparison of the two figures repre-
senting it (drawn from two small spirit specimens from the Gulf Stream, found in a bottle
from the "Albatross" Expedition, 1886), and of my figures of Anthophysa darwinii
(PI. XII. figs. 8, 9, printed in 1887), informs us that these two Anthophysidse are very
closely allied, or perhaps identical. Plceophysa of Fewkes is an Anthophysid (either
Athorybia or Anthophysa) which has lost its bracts, and the pneumatophore of which,
highly retracted, is embraced on the ventral side by the prominent cucullate nectostyle.
Fewkes calls this lamellar cowl-shaped nectostyle the hood, " and supposes it to be a new
organ, elsewhere unknown among Physophores in this form " (p. 318). He even regards
Plaophysa as the type of a new family — Ploeophysidaj (p. 320).

REPORT ON THE SIPHONOPHOR^E. 281

Order IV. AURONEOLE, Haeckel, 1888.
(Pis. I.-VII.)

Auronectx, Hkl., System der Siphonophoren, p. 43.
Aurophorid.se, Hkl., ibid., p. 6.

Definition. — Siphonophorse with a large pneumatophore, a corona of nectophores, a
peculiar aurophore, and a network of canals in the thickened trunk. Nectosome com-
posed of a horizontal corona of nectophores beyond the voluminous spheroidal pneumato-
phore, and a singular pneumadenia (the large subspherical aurophore), placed in the
dorsal median line of the corona. Siphosome spheroidal, ovate or turnip-shaped, with a
thick, bulbous, cartilaginous trunk, traversed by a dense network of anastomosing
gastro-canals ; its surface densely covered by numerous cormidia, each of which bears a
single siphon with a tentacle, and one or more gonodendra.

The order Auronectse is represented by a few Siphonophorse of the deep sea, which
were discovered by the Challenger, and which differ so widely in their entire organisation
from all other animals of their class, that it is impossible to place them in any of the
four other orders. The large apical pneumatophore, of an enormous size, is similar to
that of the Physalidse among the Cystonectse ; the corona of numerous nectophores
(wanting in these latter) resembles that of some Physonectse (Circalidse, Forskalidse) ; but
the remarkable organ of the nectosome which we call aurophore is found in no other
group of Siphonophorse, and is exclusively peculiar to the AuronectEe. The same
holds good of the thickened bulbous trunk of the siphosome, which is traversed by a
network of anastomosing canals, similar to the fleshy or cartilaginous ccenosome of the
Alcyonidse.

The few species of Auronectse which I have examined were preserved in spirit in
rather good condition, and seem to represent two different faradies of this order,
Stephalidse and Rhodalidse. The smaller Stephalidae (with the genera Stephalia,
PL VII., and Stephonalia, PL VI.) seem to be allied to the Circalidae among the
Physonectae (Circalia, PL XXI. figs. 1-4). Their bulbous trunk exhibits an axial central
canal, with a mouth at the distal end (PL VII. figs. 40, 48). The tentacles are simple,
without tentilla. The second family contains the larger and more highly developed
Rhodalidse (Rhodalia and Auralia, Pis. I.-V). The axial central canal of the bulbous
trunk has here disappeared, or is replaced by a central cavity ; its distal mouth-opening is
lost (PL IV. fig. 15). The tentacles are compound, with a series of lateral branches
or tentilla, similar to those of the Forskalida?. The young larval forms of the Rhodalidae
seem to be little different from the adult Stepkalidse.

Nectosome and Siphosome. — The two main portions of the corrn, swimming and
feeding body, are both distinguished in the Auronectse by a peculiar development. The

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 36

282 THE VOYAGE OF H.M.S. CHALLENGER.

nectosome, in the superior or apical half of the corm, is composed of three different
portions: (l) a gigantic spheroidal or lenticular pneumatophore ; (2) a horizontal corona
of numerous radially arranged nectophores beyond the float ; and (3) a pyriform or
subspherical aurophore placed in the dorsal median line of the corona, probably an
enlarged pneumadenia. The siphosome, which occupies the inferior or basal half of
the corm, is composed of a large bulbous axial trunk and of numerous peripheral
cormidia, which cover its whole surface. Each cormidium bears upon a short common
pedicle a single siphon with a tentacle and one or two monoclinic gonodendra, provided
with one or more sexual palpons.

Pneumatophore (p, PL I. fig. 1 ; PI. III. figs. 13, 14 ; PI. IV. fig. 15 ; PI. VI. figs.
32, 33 ; PL VII. figs. 39, 40, 48, 50). — The apical float filled with air is very volumin-
ous, comparatively larger than in any other known Siphonophorse, with the sole excep-
tion of the Physalidse. It is about half as large as the bulbous siphosome and has the
form of an inflated lens or a flattened spheroid, its vertical diameter (or central axis)
being usually only half as long as the horizontal diameter (or the transverse axis) ; the
former in the largest specimens of Rhodalia measures 10 to 11 mm., the latter 20 to
22 mm. The horizontal section of the pneumatophore (figs. 1, 16, p) is circular, the
vertical section (figs. 15, 40, 50, p) elliptical. The greatest part of its surface is free and
smooth. Only the lower surface is attached to the truncated proximal face of the stem
and separated from it by the flat horizontal hypocystic cavity (figs. 15, act, 40, ah).
The dorsal side of the pneumatophore bears at its base the large aurophore (I), whilst on
the opposed ventral side the set of buds is placed (PL IV. fig. 15, i).

Although the development of the pneumatophore in the Auronectse is unknown,
there can be no doubt that it originates in the same way as in the Physonectse and
Cystonectse ; it represents, as in these latter, the modified umbrella of a Medusa, the
manubrium of which is the trunk of the siphosome (PL VII. figs. 40, 50). Since the large
air-sac is produced by an invagination of the apical part of the tubular trunk or
ccenosome, its wall is hollow, and the cavity of the wall filled by nutritive fluid ; the
pericystic cavity (PL V. fig. 24, ps) communicates below with the flat hypocystic cavity
(PL IV. fig. 15, aa). This latter is a simple circular or lenticular cavity without septa.
But the pericystic cavity is traversed by a variable number of irregular trabecule or
radial septa, which connect the thicker outer wall (pneumatocodon) with the thinner
inner wall (pneumatosaccus).

Pneumatocodon. — The outer wall of the float (PL V. figs. 24, 30, z) is rather thick,
very firm and elastic, and is composed of five strata, viz. — (1) the outer exodermal
epithelium (e); (2) a subjacent layer of longitudinal or radial muscles ; (3) a thick fulcral
plate (2) ; (4) a thin stratum of circular muscles ; and (5) an inner exodermal epithelium
(d). The exodermal cell-layer, or the epidermis, is a thin and flat pavement epithelium.
The strong subjacent muscle-plate is composed of longitudinal fibres which diverge-

REPORT ON THE SIPHONOPHORiE. 283

radially from the apical centre of the float and surround it like meridional arches (fig.
40). Sometimes eight stronger equidistant radial muscles are developed (fig. 33). The
fulcrum, or the supporting gelatinous plate, is a hyaliue and structureless cartilaginous
lamella 0"2 to 0'5 mm. thick; it is twice as thick in the peripheral as in the apical
part of the float. The fulcrum is pierced (mainly in the basal periphery) by a variable
number of simple or branched radial cords, which connect its inner and outer epithelium.
They are partly solid apophyses of the entoderm (fig. 30, dj, partly nutritive canals ;
sometimes these canals seem to open on the outer surface of the pueumatocodon.
The stratum of ring-muscles which lies inside the fulcrum is thinner than the outer ,
layer of radial or longitudinal muscles ; but sometimes the circular muscles are also
well developed, and effect a horizontal annulation of the float. Stephonalia (PL VI. figs.
32, 33), which exhibits outside eight strong radial muscle-bands, is distinguished also
by a peculiar development of parallel muscle-rings on the inside of the pneumatocodon.
The entodermal epithelium which lines the inside is always composed of large cylinder-
cells (fig. 30, d).

Pneumatosaccus. — The air-sac, or the inner (originally invaginated) wall of the pneu-
matophore, is of the same form as the somewhat larger surrounding pneumatocodon (or
the outer wall), separated from it by the pericystic cavity (fig. 2-4, ps), and connected with
it by the above-mentioned numerous trabeculse. The inner wall is much thinner than the
outer, and composed of three plates only, viz.- — (l) the entodermal epithelium composed of
high cylinder-cells (PI. V. fig. 24, dt) ; (2) a rather thin, but firm and elastic fulcrum (the
structureless supporting plate, fig. 24, zx) ; and (3) the exodermal epithelium composed of
much smaller cells (fig. 24, e^) ; this inner surrounds and produces the pneumatocyst.

Pneumatocyst. — The air-flask of the Auronectse is a thin but firm and elastic cuticle,
secreted and surrounded by the pneumatosac, therefore of the same form and size. It
has no apical stigma, as in the Cystonectse, but is everywhere closed, except at the single
basal opening, which we call auropyle (PL IV. fig. 16, li, seen from above ; PL V. fig. 24,
li, seen in the sagittal section). This auropyle lies excentrically in a small circular
dimple on the dorsal base of the pneumatocyst, in its sagittal axis. The periphery of
this dimple (foveola auropylaj) marks the internal boundary between the pneumatophoie
and the attached aurophore. The chitinous plate of the pneumatocyst seems to be
continued directly into the vagina pistilli (If). Compare below.

Aurophore (PL IV. figs. 15, 10,/; PL V. figs. 24-28 ; PL VII. figs. 39, 40, 48, I).—
The aurophore or air-bell of the Auronectae is a peculiar and most remarkable organ,
wanting in all other known Siphonophorse ; it seems to be the modified umbrella of a
medusome, or a peculiar medusoid person, which was originally a modified nectophore,
and adapted to the production and emission of the gas contained in the large pneumato-
phore. The form of the aurophore (/, PL I. fig. 1 ; PL III. figs. 13, 14 ; PL IV. figs. 15,
16) is roundish, nearly globular or somewhat pear-shaped ; it is attached by a broad

284 THE VOYAGE OF H.M.S. CHALLENGER.

base to the inferior part of the dorsal side of the pneumatophore and placed in the sagittal
plane. In Stephalia (PI. VII.) it is of the same size as a nectophore ; in Rhodalia
(PL III.) much smaller. The comparison of the vertical sagittal section (PI. V.
fig. 24 ; PI. VII. fig. 40) and of the vertical frontal section (PI. V. figs. 25, 26)
proves that the aurophore possesses a singular medusoid structure ; it is pierced by
a cylindrical central canal, the auroductus (la) running in a nearly horizontal direction and
opening inside into the cavity of the pneumatophore by the auropyle (figs. 16, 24, li),
outside by an external mouth, the aurostigma (figs. 15, 24, 40, lo). The auroduct or
central canal is lined inside by a thick-walled peculiar tube, the pistillum ; while it is
surrounded outside by a number of radial chambers, which are separated by septa and
communicate with the pericystic cavity of the pneumatosaccus.

The remarkable structure of the single parts of the aurophore, compared with the
corresponding parts of the nectophores and the pneumatophore, makes it probable that
the aurophore is a modified nectophore, transformed into a pneumadenia ; in this case it
has the morphological value of a medusoid person. On the other hand, it is possible
that it was originally only a secondary organ of the pneumatophore, a basal apophysis of
the air-funnel (PI. VII. fig. 50). Perhaps its outer opening corresponds to that which
the Discolabidse exhibit at the base of the pneumatophore.

The transverse section of the aurophore (PI. V. fig. 25, in the proximal part; fig. 26,
in the middle part) exhibits in its outer wall from outside to inside the following five
strata: — (1) A simple exodermal epithelium (e) composed of rather flat small cells;
(2) a muscular plate composed of longitudinal muscle-fibrillae, which are probably direct
prolongations of the epithelial cells ; (3) a thin cartilaginous fulcra! plate (z), much
thinner than the same fulcrum of the pneumatophore, but very firm and elastic, consisting
of structureless jelly, strongly stained by carmine ; (4) a thin layer of ring-muscles ;
(5) a thick entodermal epithelium, composed of very large cylindrical cells.

The same five strata recur also in the inner wall of the aurophore, following,
however, in the inverse order ; the entoderm lying outside, the exoderm inside. The
latter surrounds the central cavity of the aurophore, which is filled by the pistillum;
between them is visible the vagina pistilli, a structureless tube (If) intensely stained by
carmine; it seems to be a chitinous cuticular membrane, formed by a direct prolongation
of the pneumatocyst (pf).

The outer wall of the aurophore (exumbrella) and the inner wall (subumbrella) are
connected by a variable number of radial septa ; and by these are separated wide radial
chambers (figs. 24—26, Ir). These correspond probably to the radial pouches of the
pneumatophore in the Physonectse, and to the radial canals of the medusoid nectophores ;
they are, however, much wider than the latter. Their number is variable ; usually
between eight and twelve. In the middle part of the aurophore (in transverse sections
which cut the pistillum at right angles in its middle part) eight to twelve radial

REPORT ON THE SIPHONOPHOR^. 285

chambers appear sometimes rather regular (fig. 26, Ir) ; but in other transverse sections
(more proximal and oblique, placed nearer to the auropyle, fig. 25) the number, size,
and form of the radial chambers is rather different, owing to the ramification and
arrangement of the separating radial septa. Near the auropyle this arrangement is so
symmetrical that the form of the transverse section is quite bilateral (fig. 25).

The fulcrum of the outer as well as of the inner wall of the aurophore arises between
the radial septa in the form of numerous smaller and larger crests which project into
the cavities of the radial chambers, and these crests are covered by high folds of the
entoderm. The form of the canal-system of the aurophore becomes very complicated
by further development of these entodermal folds, and in the largest specimens examined
assumes the shape of a spongy system of irregular lacunae. The great internal surface
of the entodermal epithelium, thus produced, together with the extraordinary size and
glandular appearance of its high cylindrical cells (fig. 27, d), make it probable that the
great mass of air contained in the pneumatophore is secreted by the lacunar system of
the aurophore and conducted into the cavity of the pneumatocyst by pores, which
pierce the inner wall of the aurophore.

Pistillum (PI. V. figs. 24-26, Ip). — The peculiar body, which fills up the
cylindrical central cavity of the aurophore, and which we call provisionally pistillum, is
a very remarkable organ, the true morphological signification of which cannot be fully
recognised without knowledge of its development. It seems not to be comparable with
any structure known hitherto in other Siphonophorse (except perhaps the tapetum
endocystale of the Physonectse ?), and is a singular production of the Auronectse.
The comparison of the sagittal section of the aurophore (PI. V. fig. 24) with the
transverse sections (figs. 25, 26) informs us that the pistillum is a cylindrical tube, with
a very thick wall and a narrow axial canal (la). Its wall is composed of three different
strata, the inner of which is epithelial (le), the middle muscular (fy>), and the outer
cuticular (vagina pistilli, If). The narrow axial canal of the aurophore (figs. 24-26, la)
runs in its middle part nearly horizontally ; its proximal or inner part is turned
obliquely upwards and opens into the cavity of the pneumatophore by the auropyle
(li) ; its distal or outer part is turned obliquely downwards and opens externally by
the aurostigma (lo). The simple epithelium (fig. 28, le) which lines the axial canal (la)
is composed of small cubical cells, and seems to be a direct continuation of the exodermal
epithelium ; both are in continuity at the thickened lips of the aurostigma (fig. 24, lo).
The main mass of the pistillum is composed of prolonged fusiform cells which have the
greatest resemblance to spindle-shaped muscle-cells (fig. 28, lm). All these spindle-
cells run parallel one to another and to the axis of the auroduct, and their oblong
nuclei (fig. 28, In) have also the same direction. The protoplasm of the spindle-cells is
finely granulated, opaque, yellowish, and sometimes it seems to be transversely striated.
Therefore the entire mass of the pistillum (besides the axial epithelium) seems to

•28(5 THE VOYAGE OF H.M.S. CHALLENGER.

be a bundle of parallel spindle-shaped muscle-cells, and is probably an inner prolongation
of the exodermal muscle-stratum of the outer wall. The inner insertion of the
pistillum forms a broad circular ring in the " foveola auropylse" of the pneumatophore.
This foveola (fig. 16, pi) contains the auropyle or the inner opening which leads
from the axial canal of the aurophore into the large cavity of the pneumatophore.
The longitudinal muscle-fibres of the pistillum diverge here in a radial direction hori-
zontally, and are inserted at the circular margin of the foveola, ending abruptly with
a sharp boundary line on the pneumatocyst (fig. 24, Ip1).

Judging from these peculiar structures of the pistillum, we suppose that it acts as a
strong muscle, by the contraction of which the aurophore is opened and the air contained
in the pneumatophore expelled. Its morphological explanation is very difficult ; one
might suppose it to be a part of a modified stomach (manubrium) of the medusoid
person ; more probably, however, it is a secondary apophysis of the exoderm only
(similar to the endocystic tapetum of the Physonectae), grown inside from the spira-
culum into the central cavity of the aurophore, which corresponds to the umbrella-
cavity of the Medusa. In this case the margin of the aurostigma (lo) may be compared
perhaps with the umbrella margin of the Medusa, and the pistillum with its velum
turned inside into the umbrella cavity (?).

Nectophore^ («). — The nectocalyces or swimming-bells form an elegant corona round
the base of the pneumatophore. This corona is simple in Stephalia (PI. VII. figs. 39,
40, 48) and in Auralia ; it is multiple in Stephonalia and Rhodalia (PI. I. fig. 1 ; PI. II.
fig. 6 ; PI. III. figs. 13, 14). The circular corona is bisected in the sagittal plane of the
body, on the dorsal side by the aurophore (I), on the ventral side by the set of buds (?'). The
nectophoivs are pyriform medusoid persons of equal size ; their number is eight to six-
teen in Stephalia, twenty to thirty in Stephonalia, fifty to eighty or more in Rhodalia.

Pedicles of the Nectophores. — The swimming-bells are attached on the periphery of the
cylindrical nectosome (or the upper half of the bulbous trunk) by means of large lamellar
pedicles, similar to mesenterial plates (PL III. figs. 13, 14). Each pedicle is a thin trans-
parent lamella of quadrangular or nearly square form, and consists of a cartilaginous
vertical jelly-plate placed in a meridional plane of the trunk. The thinner upper and the
thicker lower margins of the pedicle are free ; the inner or axial margin is thickened and
arises by a broad base from the ccenosome ; the outer or abaxial margin passes over
into the conical apical part of the nectophore (PI. IV. fig. 16, np). A wide canal, the
peduncular canal of the nectophore (PI. V. fig. 31, ns), arising from the network of canals
in the ccenosome, and placed radially to its vertical main axis, runs horizontally along
the thickened lower margin of each pedicle, and gives off at right angles a series of
twenty to thirty small, lateral, vertically ascending branches. These branches, or the
"secondary peduncular canals" (nl), are therefore directed parallel to one another and to
the vertical main axis of the trunk ; they are single, blind, slightly curved or undulating,

REPORT ON THE SJPHONOPHORjE. 287

and decrease gradually in size from the axial to the abaxial margin of the pedicle. The
distal or abaxial end of the horizontal main canal (ns) of the pedicle passes over into the
canal-cross which is formed by the four radial canals of each nectophore. The jelly-
lamella of the pedicle is covered on both sides by a strong muscular plate composed of
horizontal parallel bundles of radial muscle-fibres, which run parallel to the upper and
lower margins of the pedicle (fig. 31, nm). The surface of the muscular plate is covered
by a flat pavement epithelium of the exoderm.

The arrangement of the nectophores arouud the trunk is different in the various
genera of Auronectae. All the swimming-bells lie in a single horizontal plane, radially
arranged, in Stephalia and Auralia (PI. VII. figs. 39, 40, 48). But in Stephonalia and
in the larger Rhodalia, where they are much more numerous, they compose probably
three alternating horizontal rings, as is supposed in the semi-diagrammatic figures
(PL III. figs. 13, 14). In the specimens preserved in spirit examined, the majority of the
nectophores were detached from the ccenosome and their form much altered by contraction.
The remaining axial parts of their pedicles, however, densely placed parallel in regular
narrow intervals, allowed their arrangement around the trunk to be recognised with great
probability (PI. I. fig. 1 ; PI. III. figs. 13, 14). Therefore, this may be very similar to
that of Forskalia among the Physonectae (PL VIII. ), with this difference, however,
that in Forshalia the common stem is much longer and more slender than in Rhodalia.
Therefore, the spiral column of the nectophores in the nectosome is here much broader
and not so high as in the former. The nectophores of the living adult Rhodalia
compose probably three transverse series, disposed quincuncially, and so alternating,
that those of the first and third transverse series are placed in the same meridional plane
of the stem, whilst those of the second transverse series are interpolated between the first
and third. But this quincuncial arrangement is only produced by mutual pressure and
dislocation of the nectophores, the basal pedicles of which form a single corona (fig. 14).
Probably the form of the pear-shaped nectophores is polyhedral by mutual compression
in the living animal, whilst it is more roundish in the contracted spirit specimens.

Each nectophore is a medusiform bell, the pear-shaped umbrella of which is
composed of a rather thick and firm jelly-plate. Its inside is covered by a strong
muscular subumbrella, composed of circular fibres. The entrance (figs. 6, 1G, w) into the
wide cavity of the nectosac is closed in the periphery by a broad circular velum, which
projects from the margin of the umbrella (figs. 13, 16, v). The entire surface of the
nectophores, as well the outside (exumbrella) as the inside (subumbrella), is covered by
a flat pavement epithelium. The main axis of the nectophores is radial to the vertical
main axis of the trunk, and therefore horizontal in the middle transverse row of
nectophores ; it is somewhat ascending in a centrifugal direction in the upper row, and
somewhat descending in the lower row (figs. 13. 14).

The nutritive canal-system of each nectophore (PL IV. fig. 17, n) is, as usual,

258 THE VOFAGE OF H.M.S. CHALLENGER.

composed of four equidistant simple radial canals (nr), which arise from the distal or
abaxial end of the primary peduncular canal, run in the subumbrella to the margin of
the jelly-bell, and are there united by a circular canal (nc), placed above the insertion of
the velum (v). Compare PI. VII. figs. 39, 48.

Tmncus. — The common stem of the corm, or the coenosarc, exhibits in the Auronectee
a most remarkable form and structure, very different from that of all other Siphono-
phorge. It is a large solid bulb of a cartilaginous consistence, sometimes subspherical
(PI. IV. fig. 15, a), at other times more spindle-shaped or truncately conical (PL VII.
fig. 40, a). Its size is usually about equal to or double that of the pneumatophore.
The solid mass of the cartilaginous trunk is structureless and colourless, hyaline,
very similar to the hyaline fundamental substance of common cartilage. It is
traversed everywhere by a dense network of innumerable small canals, anastomosing
one with another, and with the large hypocystic cavity (PI. V. fig. 24, etc). The
network is very similar to that in the fleshy coenosarc of the common Alcyonium ; but
the numerous asteroidal connective cells, which are scattered in the fundamental
substance of this latter between the vessels, are wanting in the Auronectee ; excep-
tionally here a few mesenchymatous entoderm-cells step out from the vessels and remain
isolated in the fundamental substance. The network of these nutritive vessels or
gastro-canals forms on the surface of the trunk a superficial net, from which the canals
of the cormidia arise. The entodermal epithelium which lines the canals is composed
of high cylindrical cells, forming a single layer (PI. V. fig. 29).

The Stephalidse (Stephalia, PI. VII. fig. 40) differ from the larger Rhodalida?
(Rhodalia, PI. IV. fig. 15) in the possession of a wide, cylindrical, central canal (ca),
which descends vertically in the main axis of the turnip-shaped trunk and opens at its
distal pole by a mouth. This terminal mouth is sometimes much larger than the mouth-
openings of all the other siphons (PI. VI. figs. 32, 33, ap). There can be no doubt in my
opinion that this important axial canal is the gastral cavity of the protosiphon, or
the primary siphon of the larva, which is the manubrium of the original medusome.
Its distal opening is the original Medusa-mouth. This explanation becomes evident by
the comparison with the youngest larva observed (Auronula, PI. VII. fig. 50). The
entire siphosome is here represented by the single primary siphon. By thickening of
its wall and development of nutritive canals in it arises the vascular bulbous trunk of
the Auronectse. It corresponds to the basal protosiphon at the distal end of the
Physalidae, and to the sterile central siphon of the Disconectse.

Cormidia. — The entire surface of the bulbous trunk beyond the corona of
nectophores is in all Auronectae densely covered with numerous cormidia. Their
number is in the smaller Stephalidse twenty to fifty or more, in the larger Rhodalidaj
sixty to eighty, often more than one hundred, or even several hundreds. The cormidia
are always monogastric and originally ordinate, arranged in regular circles or spiral coils

REPORT ON THE SIPHONOPHOR^. 289

(PI. IV. figs. 16, 17); but the intervals between the neighbouring cormidia, or the
internodes of the stem, are so small, that the arrangement often appears to be more
irregular, and the whole surface of the siphosome is like a bunch of cauliflower (PL II.
fig. 6 ; PI. III. figs. 13, 14). Each cormidium arises from the surface of the common
trunk by a thickened base, which is sometimes a short conical protuberance, at other
times a longer cylindrical pedicle, or a lateral branch of the trunk (PI. IV. figs. 15, 16).
Sometimes the cormidia seem to arise united in small groups from a common pedicle,
and if we regard one of these groups as a single cormidium of higher order (or a main-
branch of the trunk), we may say that the cormidia are polygastric (PI. VI. figs. 34, 35).
In some specimens (or perhaps in certain species ?) the arrangement seems to be more
irregular, and the cormidia more or less loose. The common pedicle of each cormidium
is traversed by a network of anastomosing canals, often with a wider axial main canal.

Each cormidium is originally composed of the following four organs (PI. VI. fig. 37) :
(1) a single siphon (s) ; (2) a long tentacle arising from its base (t) ; (3) a clustered
monostylic gonodendron (</); and (4) a slender palpon arising from its distal portion (q).
This regular composition of the monogastric and ordinate cormidia is obvious in the
majority of the specimens examined. But in some specimens of larger size the two main
branches of the very large gonodendron are so deeply divided, that two gonodendra
arise separately from the common base of the cormidium (PI. I. fig. 2). More rarely
there are single cormidia, in which the two gonodendra (or only one of them) are again
forked, so that three or even four gonodendra arise from separate pedicles.

Siphons (PL IV. figs. 19, 20, s ; PL VI. figs. 32-38, *; PL VII. figs. 39-42, *).— The
feeding polypites of the Auronectse exhibit in general the same form and structure as in
the Physonectse. They are in the spirit specimens observed all more or less contracted,
thick-walled, spindle-shaped or cylindrical tubes, tapering towards the basal as well as
the distal end. Their length in the small Stephalidse is 2 to 4 mm., in the large Rhodalidse
8 to 1 0 mm. ; their breadth in the former 0-6 to 0"8, in the latter 2 to 3 mm. In the expanded
state they may reach double the size or more. The four usual segments of the siphons
are often very distinct. The cylindrical pedicle (sp) which arises from the cormidium is
a thick-walled cylindrical tube of variable length, opening inside in the main canal of the
cormidium, outside in the basigaster. The transverse section of the pedicle is very similar
to that of a gonostyle (PL I. figs. 4, 5) ; it exhibits a thick, structureless, cartilaginous
fulcrum, from the convex outside of which arise numerous branched radial folds (z1).
These bear the parallel fibres of the longitudinal muscles (ml), while the concave inside
of the fulcrum is lined by a thin muscle-plate composed of circular fibres (mc). The
entodermal epithelium, inside the latter, forms a single layer of high cylindrical cells (d),
whereas the exodermal epithelium covering the outside is stratified, composed of three to
six or more layers of polyhedral cells (e).

The second segment of the siphons is the basigaster (figs. 37, 38, sb), usually a herui-

(ZOOL. CHALL. EXP. PART LXXVU. — 1888.) Ilhhh 37

290 THE VOYAGE OF H.M.S. CHALLENGER.

spherical or pyriform portion, the thickened exoderm of which is full of cniclocysts.
From its base arises the single tentacle (figs. 35, 37, 42, t). The basigaster is separated
from the pedicle as well as from the stomach by an annular constriction (sphincter). The
basal sphincter is a very strong ring-muscle, and it is very probable that by its sudden
contraction the three distal segments are frequently detached from the proximal pedicle.
In my preliminary examinations of the large and well-preserved specimens of Rhodalia
miranda collected by the Challenger, I could find in them neither siphons nor tentacles.
I saw only the pedicles of the siphons attached to the corrnidia, and judged them
to be the highly contracted siphons, and their opening (the pylorus basalis) to be the
true mouth. I was thus led into the same error as Gegenbaur thirty years before in
Stephanospira. Some time afterwards I examined accurately the masses of horse-hair
covering the bottom of the vessel in which the Rhodalia had been packed by the
naturalists of the Challenger. There were entangled between the horse-hairs some
irregular whitish lumps composed of interwoven long filaments and nodes. Further
careful examination convinced me that the long coiled up filaments were the tentacles
of Rhodalia, and the nodes were the detached siphons connected with the former
(PI. IV. fig. 20). Along time afterwards I received from Dr. John Murray the complete
specimens of Stephalia corona taken in the " Triton" Expedition (1882), and in these the
majority of the siphons and tentacles were still connected with the corrnidia (PI. VII.).
Supported by this confirmation of my suggestions, I was able to restore the anatomy of
Rhodalia, and to draw the entire corm with that completeness which is figured in PI. III.
At the same time this experience teaches afresh the lesson that much care and critical
judgment must be employed in the anatomical examination of preserved specimens of
Siphonophorse, and of such specimens as come up in the tow-net or trawl from the deep-
sea. Many parts of the corms, especially the nectophores and tentacles, but also often
the siphons and palpons, are so easily detached, that they seem to be entirely wanting.
I have no doubt that the " deep-sea Siphonophorse, without tentacles," which have been
described by Studer (40), Fewkes (45), and by former authors, are corms which have lost
the tentacles during capture.

The stomach (sm), as the third and largest portion of the siphons, is a long cylindrical
or spindle-shaped tube, often ovate in the inflated state, and separated by an annular
constriction from the two neighbouring segments, the proximal basigaster (sb) and the
distal proboscis (sr). It is easily distinguished from both by the dark longitudinal liver-
stripes, which extend parallel and equidistant in its whole length (PI. IV. fig. 20, sh ; PI.
VI. figs. 35, 38, sh ; PL VII. fig. 42, sh). The number of these hepatic ridges seems to be
variable, sometimes eight, at other times twelve or sixteen. After removal of the glandular
entoderm, the remaining exoderm of the stomach exhibits a large number of longitudinal
parallel muscle-bands (PI. IV. fig. 19, ml). No doubt the siphons are very expansible and
contractile, as usual.

REPORT ON THE SIPHONOPHOR^. 291

The proboscis, the fourth and last segment of the siphon, is in the spirit specimens
examined usually short, highly contracted, and conical (PI. IV. figs. 19, 20, sr ; PI. VII.
fig. 42, sr). Often its proximal part is invaginated and turned over by the reflexed distal
part (PL VI. figs. 35, 37, 38, sr). Sometimes four or eight strong longitudinal muscle-
bands may be distinguished in the outer wall of the proboscis. The inner wall seems to
be beset with peculiar glandular cells. The distal mouth is usually highly contracted,
circular, with a thickened labial margin ; often it shows a circle of radial folds or lobes,
the number of which is sometimes four or eight, at other times twelve or sixteen (PI. VI.
figs. 35, 37, sr1).

Tentacles. — Each siphon bears in the Auronectse, as in all other Siphonanthae, a single
long tentacle, and this arises from the basigaster, near its basal part. As mentioned
above (p. 290) the tentacle remains attached to the basigaster, when the siphon becomes
separated from the cormidium by self-amputation (sudden contraction of the basal
sphincter), whereas the pedicle of the siphon remains attached to the corm.

The tentacles of the Auronectse appear in two different forms, characteristic of the
two families of this order. The small Stephalidae (Stephalia, PI. VII., and Stephonalia,
PI. VI.) have simple, not branched tentacles, similar to those of the Apolemidaj and
Linop>hysa. The large Rhodalidae, however (Rhodalia, PI. III.; PI. IV. figs. 20-23), possess
branched tentacles, like the majority of Physonectae ; each tentacle bears a series of very
numerous tentilla or lateral branches ; in form and structure (fig. 23) they are very similar
to those of the Forskalidae.

The simple tentacles of the Stephalidae are long and thin cylindrical tubules, and arise
from the dorsal side of the basigaster near its pedicle (PI. VII. figs. 39, 40). They are
usually very much contracted in the spirit specimens examined, and not much longer
than the siphons ; but in the expanded state and in the living animal they are probably
very long, several times longer than the whole corm. The tentacles of Stephalia (PI. VII.
figs. 39, 40) are all of the same size and similar form, not annulated, with equally disposed
cnidocysts. But Stephonalia (PI. VI.) possesses two different kinds of tentacles, larger
superior and smaller inferior. The thinner tentacles, much more numerous, agree with
those of Stephalia. The thicker tentacles, only developed in the proximal part of the
trunk, are far larger cylindrical tubules, and appear elegantly annulated when examined
by a weak lens ; each prominent annulus is composed of densely crowded cnidocysts,
wanting in the small constricted interval between each two rings (PI. VI. figs.
35, 37, 38, t). The distal part of these thicker tentacles has a peculiar structure; it
represents a cylindrical, articulated terminal filament, composed of about a dozen
segments, and bearing no annuli of cnidocysts (figs. 35, 37, tf).

The branched tentacles of the Rhodalidae have a similar but more complicated
structure, and each bears a series of very numerous tentilla or lateral branches. The
cylindrical tube, which is 1 to 1*5 mm. in diameter, may reach in the fully expanded state

292 THE VOYAGE OF II.M.S. CHALLENGER.

a length of 1 metre or more. It is annulated in the same manner as the simple
tentacle of the Stephalidae ; but from the interval between each two annnli arises a
tentillum or accessory filament (PI. IV. figs. 20-22). The line in which these numerous
tentilla are inserted is the dorsal median line of the cylindrical tentacle. From the
opposite ventral median line arises a very thin and broad ligament, the suspensorium ten-
taculi (PL VII. fig. 42, tg); it is similar to the well-known suspensorium or tentacle-band
of the Physalidse; and as in these latter, the tentacle when contracted is coiled up spirally
around this axial ligament. The transverse section of the tentacle, when magnified, shows
us that the elastic ligament is composed of a solid lamellar apophysis of the cartilaginous
fulcrum (PL IV. fig. 21, tl), and is covered by a single layer of exoderm-cells (e).

The structure of the tentacle visible in the transverse section (PL IV. fig. 21) is
similar to that of other Siphonanthse. The cylindrical central canal (c) is lined by a
simple layer of large entoderm-cells (d), and this is surrounded by a thin muscular tube
composed of circular fibres (mc). This entodermal plate is separated from the thicker
exodermal wall by a strong gelatinous fulcrum of nearly cartilaginous consistence
(2). The structureless fulcrum or supporting plate is surrounded in the transverse
section by a corona of numerous (seventy to ninety) radii ; they are the transverse
sections of large longitudinal radial jelly-lamellse which support the strong longitudinal
muscle-fibres (ml). The latter appear in the transverse section regularly arranged on
both sides of the lamellae, like a pinnate leaf. The outer envelope of the exoderm (e)
is very thick and composed of a stratified epithelium including may thread-cells. The
circular annuli of the exoderm, composed of the radial supporting lamella? and the parallel
bundles of longitudinal muscles, are not quite complete, but interrupted on the ventral
side by the broad elastic ligament of the tentacle or the suspensorium (tl).

Tentilla (PL IV. fig. 23). — The accessory filaments or tentilla of the Ehodalidag are
simple lateral branches of the main tentacle, arranged in a single series in its dorsal
median line. This series is opposed to the large, mesentery-like elastic ligament.
The length of the lateral branches, which commence as very small bud-like elevations in
the proximal part of the tentacle, increases gradually towards its distal end ; the longest
tentilla have a length of 5 to 10 mm. or more. The fully developed tentillum (PL
IV. fig. 23) is very similar to that of Forskalia (PL X. fig. 23). It consists of three
cylindrical parts, viz., a short pedicle (tb), a spiral cnidoband (tk), and a slender terminal
filament ({/). The short pedicle (tb) is inserted with narrow base in the interval
between two thickened annuli of the main tentacle (fig. 22) ; its epithelium bears only
very small cnidocysts. The cnidoband (tk) is armed with a strong cnidobattery, and is
a thick-walled cylindrical tube coiled up in several lseotropie spirals. On its ventral
or axial side are attached two strong parallel elastic ligaments (the so-called " angle-
bands," fig. 23, tl), and on both edges of these a series of very large bean-shaped or
ensiform lateral cnidocysts (tk\), whilst the convex dorsal side of the cnidobattery bears

REPORT ON THE SIPHONOPHORJE. 293

a regular pavement composed of innumerable small paliform cnidocysts (tkn). The strong
cnidofilament protruded from the large bean-shaped cnidocysts is a rather thick and
spirally convoluted thread (PI. VII. fig. 43, a, b). The slender terminal filament of the
tentilla (fig. 23, tf) is a simple cylindrical blind tube, scarcely half as broad as the
battery, and armed with roundish cnidocysts of medium size.

Gastro-canal System. — The system of nutritive vessels of the Auronectse is more
complicated than that of the other Siphonophorse (with the exception of the Disconectse).
It is composed of the following parts: — (l) The central hypocystic cavity of the trunk
(PI. IV. fig. 15, aa ; PL VII. fig. 40, ah) ; a large circular horizontal cavity of
discoidal form, the apical wall of which is formed by the lower part of the pneumato-
phore, the basal wall by the uppermost part of the siphosome. (2) The pericystic cavity
of the pneumatosaccus (PI. V. fig. 24, ps), enclosed between the thicker outer and the
thinner inner wall of the pneumatophore ; it gives off small irregular lateral branches
which pierce the thick wall of the pneumatocodon (fig. 30). (3) The cavity of the
aurophore (PI. V. figs. 24-26, Ir), divided by numerous irregular, partly radial, partly
branched septa into a spongy system of lacunar vessels and radial chambers ; the
basal part of the aurophore-cavity communicates on its upper side with the cavity of
the pneumatophore (fig. 24, ps), on its lower side with the central main cavity. (4)
The reticulum of truncal canals (PI. IV. fig. 15, ac; PI. VII. fig. 40, ac), composed of
a dense network of numerous irregularly branched and anastomosing vessels, which
pierce the thick cartilaginous bulbs of the trunk in every direction ; the centre of this
truncal reticulum is in Stephalia the axial central canal (fig. 40, ca) descending
vertically from the centre of the main cavity towards the basal central siphon and
opening through its mouth. (5) The ventral buckling canal (PI. IV. fig. 16, ic),
running from the ventral median line of the central hypocystic cavity to the
ventral series of buds (i), and giving off a lateral branch to each bud. (6) TJte
nectocalycine ducts, or the peduncular canals of the nectophores (PI. V. fig. 31, ns),
arising from the stem-cavity, running horizontally along the basal edge of the peduncle,
and giving off a unilateral series of lateral branches which ascend vertically (fig. 31, nl).
(7) The four radial canals of each nectophore (PI. IV. fig. 17, nr; PL VII. fig. 39);
they arise crossed from the distal end of the peduncular canal, run along the sub-
umbrella towards the margin of the nectophore, and are there united by a circular canal
(fig. 39, cc). (8) The centred canal of each cormidium, and the network composed of its
anastomosing branches, often united by subregular elegant arches with the network of the
neighbouring cormidia. (9) The simple siphon cavity (PL I. fig. 4, c) composed of four
segments (pedicle, basigaster, stomach, and proboscis); it arises from the superficial canal-
network of the cormidium and gives off from the basigaster a lateral branch for the tentacle
(tentacular canal, PL IV. fig. 21, c). (10) The simple gonostyle caned (PL I. figs. 2, 3, c ;
PL II. figs. 7, 8 ; PL VII. fig. 49), arising from the superficial canal network of the

294 THE VOYAGE OF H.M.S. CHALLENGER.

corruidia, and branching irregularly, giving off a special canal to each branch of the
gonodendron and to each gonophore budding from it. (11) The palpon canal (PI. IV. fig.
18, q), the simple blind cylindrical cavity of the gonopalpon, which arises from the distal
end of each gonodendron. (12) The gonophore canal, running through the pedicle of each
gonophore to the centre of its subumbrella, and dividing there into four radial canals which
are united at the margin by a ring-canal. (13) The spermarial canal (PI. VII. fig. 46),
or the simple central cavity in the axis of each androphore (spadix), arising from the
centre of its subumbrella and being the direct prolongation of the gonophore-canal. (14)
The ovarial canal, arising from the centre of the subumbrella of each gynophore (as the
prolongation of its pedicular canal), and running either in the axis of the ovarium as a simple
spadix (PI. II. figs. 9, 10, c), or forming an irregular network of spadicine canals around
the egg.

Gonodendra. — The corms of the Auronectae are monoecious, the cormidia monoclinic,
and the gonodendra monostylic. Each cormidium bears in the small Stephalidae a simple
gonostyle with a single gonopalpon (g), a single androphore (h), and several gynophores
(/), usually between ten and twenty (PI. VI. figs. 32-38 ; PI. VII. figs. 48, 49). The
large Rhodalidae, however, bear on each cormidium one or two clustered gonodendra,
each branch of which corresponds to the small monostylic gonodendra of the Stephalidae,
and is composed of a few androphores and a greater number of gynophores ; usually a
single large gonopalpon is attached to each gonodendron (PI. I. figs. 2, 3 ; PI. II. figs.
6-12; PI. IV. figs. 15, 18).

Gonostyles (PI. I. figs. 2-5 ; PI. II. figs. 7, 8 ; PL VII. fig. 49, ab).— The stems of
the gonodendra, or the branched gonostyles, are in the Auronectae very thick-walled
cylindrical tubes, which arise from each cormidium near to the base of the siphon, on its
axial side (fig. 48). The wide axial canal of the gonostyle (figs. 2-4, c) is convoluted
spirally in the highly contracted spirit specimens examined, and surrounded by a strong
muscular wall of remarkable thickness. The transverse section of this wall (PI. I. figs.
4, 5) exhibits the same structure as the pedicle of the siphons. An inner thin layer of
ring-muscles (mc) and an outer thick layer of longitudinal muscles (ml) are separated by
a thick elastic fulcrum (z). This fulcral plate arises outside in the form of numerous
branched radial lamellae. The stem must be very expansible and contractile in the
living animal. The branching of the gonostyles is unilateral in the small Stephalidae
(fig. 49), dichotomous or irregular in the large Rhodalidae (figs. 3, 7, 8, 15).

Gonopalpons (PI. I. fig. 2, r ; PI. IV. figs. 15, r, 18, q ; PI. VI. figs. 37, 38, q).— The
single form of palpons or tasters, which occur in the Auronectae, are the sexual palpons
or " gonopalpons." Usually (or always V) a single tubular gonopalpon is attached to
each cormidium, as a distal branch of its gonostyle ; it is a simple cylindrical tube closed
at the pointed distal end (fig. 18, q). The gonopalpons seem to be very contractile, but
were for the most part detached and lost in the specimens examined.

REPORT ON THE SIPHONOPHOR^E. 295

Androphores (PI. I. fig. 3, h; PI. II. fig. 7; PL VII. figs. 46, 49, h).— The male
gonophores are slender medusoid persons. Their form is more or less cylindrical, some-
times more spindle-shaped, at other times more club-shaped. The basal pedicle, or the
male gonocope, is much shorter than the female. The outer envelope, or the umbrella, is
very thin walled, often armed at the distal end with four small groups of nematocysts
(fig. 46, uo). The four radial canals (fig. 46, hr), which arise from the peduncular canal and
run divergently in the subunibrella, are very narrow and difficult to observe, especially in
adult persons ; they are connected at the distal end of the umbrella by a small ring-canal
(fig. 46, he). The spermarium is formed by the thick-walled cylindrical manubrium.
The sperm (fig. 46, lis) lies, as usual, between the thin exoderm of the manubrium and
its thick entoderm, the axial spadix (hx), but separated from the latter by the fulcrum;
it has been derived from the exoderm.

Gynophores (_/*). — The female gonophores are much more varied in shape and
composition than the androphores. They are easily distinguished from these by their
more rounded (usually pear-shaped) form and their longer stalks. There occur the
following remarkable modifications : — A. Monovone gynophores. — Each female medusomc
develops only a single large ovum, (l) The gynophore develops a single very large
ovum, surrounded by a double envelope ; the inner envelope is the thin manubrial wall
containing a smaller or larger blind spadicine cavity, sometimes a network of irregular
spadicine canals ; the outer envelope is the umbrella of the medusoid person, with four
narrow radial canals and a small distal ring-canal connecting the latter ; this is probably
the normal and most frequent form of the ripe gynophore. (2) The same form, but
with four blind radial canals (reduced in the distal half). (3) The same form (as 1
and 2), but with eight equidistant regular radial canals (fig. 12). (4) The same
form (as 1 to 3), but with a variable number (five to ten) of irregular, branched
and anastomosing, spadicine canals. (5) The same form (as 1 to 4), but without
radial canals in the reduced umbrella. B. Polyovone gynophores. — Each female medusome
develops an ovarium, composed of a variable number of ovules, placed in the wall of the
modified manubrium. The umbrella seems to be usually reduced, very thin walled,
without radial canals ; often it has disappeared. (1) The gynophore is a medusome with
rudimentary umbrella ; the spadicine canal (or the original gastral cavity of the Medusa)
is central, straight, and runs in the axis of the manubrium (PI. II. figs. 9, 10); the
ovules are regularly disposed around it. (2) The gynophore is a medusome with rudi-
mentary umbrella ; the spadicine canal is excentric, curved, and runs on one side of the
manubrium ; it embraces the ovarium as a crescent-shaped or semicircular blind canal.
(3) The gynophore is a simple sporosac, the manubrium without umbrella ; the ovules
are arranged equally around the central spadicine canal. (4) The gynophore is a
compound sporosac. without umbrella, two or three (rarely more, sometimes only one)
buds developing from off the outside of the primary manubrium (PI. II. fig. 11).

296 THE VOYAGE OF H.M.S. CHALLENGER.

The buds or the secondary sporosacs contain either a single large ovum or a group
of several small ovules ; they have usually a long pedicle, and its canal arises from the
base of the primary spadix.

The different remarkable modifications of gonophores here enumerated, exhibited in
the adult spirit specimens examined, showed no regular distribution, but occurred in very
variable number and association. A further accurate research on living and well-
preserved specimens is required to make out their mutual relations and signification.

Ontogeny. — The development of the Auronectse is quite unknown, but will probably
offer interesting and valuable facts which explain the natural affinities of this interesting
order. Among the few spirit specimens of Stephalia corona which I discovered in the
collection of the "Triton" Expedition (1882), kindly forwarded by Dr. John Murray,
two specimens exhibited gonodendra (PI. VII. figs. 48, 49), whilst a third specimen
possessed no trace of them (PI. VII. figs. 39, 40). A very small medusome, found in the
same bottle (PI. VII. fig. 50), is probably a young larva of this Stephalia. This medusome
is composed of a pneumatophore (pa), an aurophore (I), a siphon (s), and a simple tentacle
(td). Unfortunately this larva (Anronula) was not well preserved, which prevented
further accurate examination.

Synopsis of the Families of Auronectse.

Trunk of the siphosome with a permanent central canal and a distinct primary mouth.

Tentacles simple, without tentilla, . . . . . . .18. Stephalidae.

Trunk of the siphosome without permanent central canal and distinct primary mouth.

Tentacles branched, with a series of tentilla, . . . . . .19. Rhodalidse.

Family XVIII. Stephalidae, Haeckel, 1888.

Stephalidx, Hkl, System der Siphonophoren, p. 43.

Definition. — Auronectse with a permanent central canal in the axis of the bulbous
trunk, opening at the basal pole by the permanent primary mouth. Tentacles simple,
filiform, without lateral branches.

The family Stephalidae comprises the smaller and inferior forms of Auronectse, with
simple tentacles and a central permanent protosiphon, opening on the basal pole of the
vertical axis by a permanent primary mouth. I was able to examine accurately only
two genera and species of this interesting family, Stephalia corona (PI. VII.) and
Stephonalia bathyphysa (PI. VI.).

The general composition of the corm, the structure of the nectosome and the
siphosome, and the form of the single organs composing them, have been described above
(p. 281). It is only necessary to add here the remark, that the Stephalidse, regarded from

REPORT ON THE SIPHONOPHORJE. 297

a phylogenetic point of view, represent the older and simpler forms of Auronectse. They
resemble the Cirealidse in many respects (PL XXI. figs. 1-4) ; and especially the mono-
gastric Auronula (PI. VII. fig. 50) may be compared to Circalia. This latter, however,
possesses no trace of the aurophore. The central axial canal of the Stephalidse (PL VII.
fig. 40, ca) and its distal mouth (ao) are of special interest, as comparable on one hand
with the terminal protosiphon in the basal cormidium of the Physalidaa, and on the other
hand with the central sterile siphon of the Disconectse. By the thickening of its wall, and
the development of anastomosing nutritive canals in this, arises the characteristic trunk
of the Auronectae. Its terminal mouth remains permanently open in the Stephalidse.

Synopsis of the Genera of Stephalidse.

Corona of neetophores simple. All tentacles simple, of the same size and form, . . 62rr. Stephalia.

Corona of neetophores double or multiple. A corona of proximal tentacles, annulated, much

larger than the simple distal tentacles, ...... 626. Stephonalia.

Genus 62a. Stephalia,1 Haeckel, 1888.
Stephalia, Hkl., System der Siphonophoren, p. 43.

Definition. — Stephalidae with a simple corona of neetophores, arranged in a single
circle. Tentacles simple, all of the same form and equal size.

The genus Stephalia (PL VII.) is the simplest and oldest (phylogenetically) among
the four different genera of Auronectae which I have examined. Its corona of neeto-
phores is simple, as in Auralia and Circalia (PL XXI. figs. 1-4), all the neetophores
being placed in one horizontal plane. The tentacles are simple, cylindrical, not annulated
filaments, all of equal size and similar form. The gonodendra (PL VII. fig. 49), which,
however, in the specimens examined were not fully developed, are smaller than in
Stephonalia, and seem to want the large gonopalpon characteristic of that genus.

Stephalia corona, n. sp. (PL VII.).

Habitat. — North Atlantic, in the depth of the eastern Gulf Stream.
Fferoe Channel and Shetland Islands, August 22 and 24, 1882 ; depth, 640 and 516
fathoms (" Triton " Expedition, Dr. John Murray).

Corm. — Four different specimens of this interesting species were examined by me,
all preserved in rather good condition. One of the corms (fig. 39, in profile; fig. 40, in

1 Stephalia = Sea-ring, oriQo;, Aluof.
(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Ilhhh 38

•298 THE VOYAGE OF H.M.S. CHALLENGER.

sagittal section) was young and immature, the cormidia being without gonophores; but the
nectophores (ten in number) attached to the trunk, and the long tentacles (about thirty)
attached to the base of the siphons, were rather well preserved. This corm had a length
of 10 mm. and a breadth of 6 mm., two other corms (one of which is represented in fig.
48) were somewhat larger and bore a small clustered gonodendron (g) on each cormidium ;
but the nectophores (except one or two) were lost, and the siphons with the tentacles
detached ; the basal pedicle of the siphons only (s) had remained on the trunk. The
number of cormidia was forty to fifty. The length of these two corms was 16 to 20 mm.,
the breadth 10 to 15 mm. The trunk of one corm was simdar to that shown in figs. 39
and 40, that of the other relatively smaller (fig. 48). The fourth specimen was the
interesting monogastric larva shown in fig. 50 (Auronula).

Auronula (fig. 50). — The remarkable larva — only a single specimen of which I could find,
after carefully examining the " Triton" collection — had a length of 4 mm. and a breadth
of 3 mm.; it represents a single medusome, the modified umbrella of which is the large,
flatly spheroidal pneumatophore (pci); the manubrium a single large central siphon (sc).
This protosiphon has a terminal mouth (ao), and bears attached to the dorsal side one single
tentacle (td), and above it a rather large aurophore (I). The relatively large size of this,
and the full development of its radial structure (Im), makes it perhaps probable that the
aurophore is not an independent medusoid person (a modified nectophore), but only a
separate basal organ of the pneumatophore. Besides some small buds on the ventral side,
no other organs were visible in this monogastric Auronula. Unfortunately it was not
well enough preserved to allow of a microtomic examination.

Nectosome (figs. 39 and 48, lateral view, from the right side; fig. 40, vertical
sagittal section). — The superior or apical half of the corm is occupied by the large spheroidal
pneumatophore (p) and the corona of nectophores (n). This is bisected in the sagittal
plane by the aurophore (I) in the dorsal median line, and by a series of buds (i) in
the ventral median line. The aurophore is in this species just the same size as each of
the nectophores ; the number of these is ten to twelve. The structure of the aurophore
(I) and its axial pistillum (lm) is the same as in Rhodalia (PI. V.).

Siphosome. — The inferior or basal half of the corm is occupied by the bulbous trunk of
the siphosome and the numerous cormidia attached to its outer surface. The cartilaginous
trunk (fig. 40, a), pierced by a dense network of anastomosing canals (ac), is sometimes
subspherical, at other times more like a spindle or a truncated cone. The axial canal (ca)
is twice as broad as its anastomosing irregular lateral branches, and opens below by the
primary mouth. Each cormidium bears a simple tentacle on the dorsal side of the
proximal base of the siphon (s), and in the mature corms a small gonodendron (fig. 49).
This is composed of a single androphore (h) and eight to twelve gynophores (f). The
gonopalpon seems to be rudimentary in this species.

REPORT ON THE SIPHONOPHORiE. 299

Genus 62b. Stephonalia,1 n. gen.

Definition. — Stephalidse with a double or multiple corona of nectophores, arranged in
two or several circles. Tentacles of two different forms and unequal sizes, larger
proximal and smaller distal.

The genus Stephonalia, represented by the remarkable deep-sea species figured in
PL VI., is closely allied to the preceding genus, Stephalia (PI. VII.), and was formerly con-
founded by me with it. But a closer examination and comparison of the two forms showed
some peculiar differences between them, which now seem to me to possess a generic value.
Firstly, the corona of nectophores, although very incompletely preserved, seems to be
composed of two (or even three) circles ; and if this be true then Stephonalia agrees
in this point with Rhodalia, and bears to it the same relation as Stephalia does to Auralia,
(both with a single circle of nectophores). A second difference between Stephalia. and
Stephonalia seems to be in the shape of the tentacles. Whilst these are all quite
simple and uniform in the former, they are of two different kinds in the latter. A third
difference is found in the development of a large gonopalpon in each cormidium of
Stephonalia, whilst this seems to be rudimentary in Stephalia. Finally, the muscles
of the pneumatophore in the latter genus are equally disposed, whdst in Stephonalia
eight strong radial muscles and corresponding meridional constrictions are marked
regularly disposed at equal distances (PI. VI. fig. 33).

Stephonalia bathyphysa, n. sp. (PL VI.).

Habitat. — South Pacific, west of Cook's Strait, New Zealand. Station 166, June 23,
1874 ; lat. 38° 50' S., long. 169° 20' E.; depth, 275 fathoms.

Corm. — Two specimens of this interesting Auronect were found by me in the
Challenger collection, both rather well preserved, although very much contracted and
altered by the action of the alcohol. The first specimen (fig. 32, seen from the left side
in profile ; fig. 33, from the dorsal side) was pretty complete, and had a length of
20 mm., a breadth of 16 mm. The second specimen, somewhat larger, but incom-
plete, had lost the greater part of the nectosome as well as of the siphosome ; but
the upper third of the latter, with the corona of large-tentacled siphons, was better
preserved than in the first specimen ; its length was 24 mm., breadth 20 mm. (figs.
34-38).

Nectosome. — The large, flatly spheroidal pneumatophore (figs. 32, 33, p>) is
distinguished by an unusual development of the muscles in its thickened wall. Eight

1 Stephonalia = Small marine corona, imGuviov, «a<o;.

300 THE VOYAGE OF H.M.S. CHALLENGER.

equidistant radial muscles run divergently from the apical centre to the basal periphery,
and these are crossed by about a dozen strong circular muscle-rings of equal breadth.
The subspherical aurophore (I) is about the same size as a nectophore. The number of
nectophores in this species, judging from the insertions of their pedicles, may be twenty
or thirty, and they seem to be arranged in a double corona, a superior and an inferior.
But the majority of the nectophores were detached in the two specimens examined,
and a more accurate examination of their arrangement is required.

Siphosome. — The complete siphosome, including the retracted appendages, is nearly
spherical, and may be about the same size as the nectosome. The sagittal section is
very similar to that of Stephalia (PI. VII. fig. 40); but the central axial canal (ac) is
wider, and the terminal protosiphon larger (figs. 32, 33, ap). The number of cormidia
may be sixty to eighty, and they seem to be arranged in a condensed low spiral. The
apical part of the trunk is surrounded by a corona of eight larger cormidia, distinguished
by very large annulated tentacles, with a slender terminal filament (figs. 34-38). The
other cormidia have slender simple tentacles, similar to those of Stephalia. Each
gonodendron (g) bears a large palpon (q).

Family XIX. Rhodalid^e, Haeckel, 1888.

Rhodalidx, Hkl., System der Siphcmophoren, p. 43.

Definition. — Auronectse without a permanent central canal in the axis of the bulbous
trunk, and without a permanent primary mouth at its basal pole. Tentacles with a series
of tentilla or lateral branches.

The family Rhodalidse comprises the larger and superior forms of Auronectae, with
branched tentacles, without permanent protosiphon and primary mouth. I was able to
examine accurately only a single genus and species of this interesting family, Rhodalia
miranda (Pis. I.-V.). A second closely allied genus seems to be Auralia, differing from
Rhodalia in the simple corona of nectophores, and in the possession of a large central
cavity in the centre of the subglobular trunk of the siphosome. The general composition
of the corm, the structure of the nectosome and of the siphosome, and the form of
the single organs composing them, have been described above (p. 281). It need
only be added here, that the Rhodalidae, regarded from a phylogenetic point of
view, represent the younger and more highly developed forms of Auronectaa. The size
of the whole corm, as well as of all its single parts, is far larger, and the number of the
cormidia and their component persons and organs far more considerable, than in their
ancestral forms, the preceding Stephalidse. The central axial canal of the latter,
and its terminal mouth, have either disappeared, or they cannot be distinguished
from the other siphonal cavities and mouth-openings. The tentacles produce a series

REPORT ON THE SIPHONOPHORjE. 301

of numerous lateral branches or tentilla. The form of the latter, and some other

characters of organisation, exhibit some similarity with the Forskalidse (Forskaliai,
Pis. VIII.-X.).

Synopsis of the Genera of Rhodalidse.

Corona of nectophores simple. Trunk of the siphosome with a large central cavity, . . 63. Auralia.

Corona of nectophores double or multiple. Trunk of the siphosome without large central

cavity, ....... .... 64. Rlwdalia.

Genus 63. Auralia,1 Haeckel, \i

Auralia, Hkl., System der Siphonophoren, p. 43.

Definition. — Rkodalidae with a simple corona of nectophores, arranged in a single
circle. Trunk of the siphosome with a wide central cavity, surrounded by a peripheral
reticulum of trunk-canals.

The genus Auralia may be regarded as the older and inferior form of Rhodalidas,
more closely allied to the preceding Stephalidse than the succeeding Rlwdalia. The
corona of nectophores is simple, as in Stephalia, and the characteristic central canal of
the trunk of the latter has left a remainder in the form of a wide central cavity, from
which the peripheral network of anastomosing trunk-canals arises. But the basal prostoma
(or the primary mouth) has disappeared, and the tentacles bear a series of tentilla, as in
Rhodalia.

Auralia profunda, the single species of this genus which I have examined,
was taken in the depths of the Tropical Atlantic, and will be described after-
wards in my Morphology of the Siphonophorae. Its external appearance is similar to
that of Stephalia corona (PI. VII. fig. 39) ; but the nectophores of the simple corona
are more numerous and the tentacles are of the same shape as in Rhodalia (PL IV.
figs. 20-23).

Perhaps belonging to this genus is another Siphonophore, from the depths of the Gulf
Stream (1395 fathoms), which Fewkes has described under the name Angelopsis globosa
(45, pt. xii. p. 972, pi. x. figs. 4, 5), and which he supposes to be a transition form
between the Pectyllidse and the Pneumatophorid (Physalia). The nectosome as well as
siphosome of this form are subglobular and of nearly equal size. The vertical section
(fig. 5) exhibits the flat hypocystic cavity (cav.), between the float-cavity (cav. p) and
the central cavity of the trunk (cav. b). The " spherical bag-like structures," which
Fewkes supposes to be " budding new individuals " (grm), are probably the necto-

1 Auralia = Air-bubble of the sea, avpa, ctXia.

302 THE VOYAGE OF H.M.S. CHALLENGER.

phores. Fewkes' description, however, is so inaccurate, and the examination so super-
ficial, that it is impossible to identify with any certainty his Angelo'psis and my
Auralia.

Genus 64. Rhodalia? Haeckel, 1888.
Rhodalia, Hkl., System der Siphonophoren, p. 43.

Definition. — Rhodalidae with a double or multiple corona of nectophores, arranged in
two or several circles. Trunk of the siphosome without proper central cavity, traversed
by an equal reticulum of trunk-canals.

The genus Rhodalia, represented by the wonderful South Atlantic Rhodalia miranda
(Pis. I.-V.), differs from the preceding Auralia in two important characters. The necto-
some is similar to that of Forslcalia, composed of very numerous nectophores, which are
not arranged in a simple corona, but in several circles or spiral rows. The trunk of the
siphosome is a solid cartilaginous bulb, without central cavity, pierced everywhere by an
equally developed network of trunk-canals. Rhodalia, therefore, represents the most
highly developed genus of Auronectse.

Rhodalia miranda, n. sp. (Pis. I.-V.).

Habitat. — Western part of the South Atlantic, south-east of Buenos Ayres. Station
320, February 14, 1876 ; lat. 37° 17' S., long. 53° 52' W.; depth, 600 fathoms.

Rhodalia miranda was preserved in rather good condition in the Challenger collec-
tion, enclosed in a spirit bottle, the clear spaces of which were filled by horse-hair.
Entangled in the latter were found the detached siphons and tentacles of the corms
(compare p. 290), whilst the detached nectophores were found in great numbers on the
bottom of the vessel. The corms themselves, as well as all their component parts,
were very much contracted by the action of the strong alcohol. In the living and
fully expanded state they are probably twice the size (or more) shown by the following
list of dimensions (p. 303). But the state of preservation, even of the most delicate
tissues, was very good, as is seen by comparing figs. 4, 5 (PI. I.), figs. 7-12 (PI. II.), and
Pis. IV. and V.

Size. — The diameter of the entire corm was in three of the preserved specimens,
on an average, between 40 and 50 mm., in the fourth smaller specimen 30 mm. The
largest specimen preserved, which is figured in Pis. I. III., twice natural size, gave the
following maximum dimensions in millimetres : —

1 Rhodalia = Sea-rose, poSo>, ahtav.

REPORT ON THE SIPHONOPHORjE.

503

Height of the corra (vertical axis), without neetophores and tentacles,

Breadth of the conn (greatest horizontal diameter),

Height of the pneumatophore (vertical),

Breadth of the pneumatophore (horizontal),

Length of the aurophore, ....

Breadth of the aurophore, ....

Length of the neetophores (with pedicles),

Breadth of the neetophores (diameter of the umhrella), .

Diameter of the trunk (vertical and horizontal axes of the siphosome),

Length of the siphons (much contracted),

Breadth of the siphons (diameter of the stomach),

Length of the tentacles (on an average),

Breadth of the tentacles, ....

Diameter of the gonodendra, ....

Diameter of the gonophores, ....

mm.
40
60
11
22

7

6
20
10
30
10

3
200

1
10

1

Figures. — Figures 1, 6, 13, and 14, which represent the complete corm (1 from
above, 6 from below, 13 from the left side, and 14 from the dorsal side), are semi-diagram-
matic, inasmuch as the detached neetophores are placed in their probable position and
form, and in fig. 13 the detached tentacles are added. Of course the form and position
of the detached neetophores could not be recognised in the spirit specimens with full
certainty, the soft jelly-substance being much contracted by the action of the alcohol. All
the other figures are drawn exactly from the preparations.

Nectosome (PL I. fig. 1, apical view from above; PL III. fig. 13, superior half,
lateral view from the left side ; fig. 14, dorsal view from behind; PL IV. fig. 15, sagittal
section). — The large pneumatophore (p) is a flattened spheroid, separated from the
subjacent trunk of the siphosome by the flat circular hypocystic cavity (fig. 15, act).
The surrounding corona is composed of fifty to eighty (or more) neetophores (n),
arranged in three alternating annular series (fig. 13) ; their high lamellar pedicles,
however, form a single corona (figs. 14, 16). The corona of the nectosome is
perfectly symmetrical, bisected by the vertical sagittal plane ; in the ventral centre
of this lies the series of buds (PL IV. fig. 16, i), in the dorsal centre the auro-
phore (/). For the peculiar structure of this latter, compare p. 283, and PL V., with
explanation.

Siphosome (PL II. fig- 6, basal view; PL III. fig. 13, inferior half, lateral view
from the left side; fig. 14, dorsal view ; PL IV. fig. 15, sagittal section). — The solid
cartilaginous trunk of the siphosome, traversed by a dense network of innumerable
canals (fig. 15), is sometimes subspherical, at other times more like a truncated cone.
Its entire surface is covered with very numerous, densely aggregated cormidia (fifty to
eighty or more). Each cormidium is a conical cartilaginous bulb, and bears a single
siphon (s) with a very long tentacle (t), and a clustered gonodendron ; the gonostyle of
the latter is originally simple (fig. 3), but often so deeply forked that two separated

304 THE VOYAGE OF H.M.S. CHALLENGER.

gonodendra arise besides the siphon (fig. 2) ; more rarely three or even four gonodendra
arise separately from one cormidium. The long tubular gonopalpon (PI. I. fig. 2, r;
PI. IV. fig. 15, r, fig. 18, q), as the distal prolongation of the original stem of the
gonostyle, seems to be always single in each cormidium.

All the corms examined had lost the nectophores, the siphons, the tentacles, and the
gonopalpons, with a few exceptions. All these detached parts were found beside the
corms in the bottle. But fortunately in some specimens one or two of these organs
had remained in their natural attachment, so that it was possible to determine their
probable natural position ; so, e.g., a single nectophore (n) in PL IV. fig. 16, and a single
gonopalpon in figs. 2 and 18. All the tentacles were attached to the basigaster of the
siphons, which were separated by self-amputation from their pedicles remaining on the
trunk (compare above, p. 290). On the structure of all separate parts compare the
general description of Auronectse (pp. 281-296).

Additional Note on the Deep-Sea Life of the Auronectse.

The new and most interesting group of Auronectse, which is one of the most splendid
discoveries of the Challenger, and described in the preceding pages (pp. 281-304, Pis.
I.-VIL), represents a new order which is adapted in a most remarkable manner to deep-sea
life. The Auronectse differ from all other Siphonophorse in the peculiar structure of the
bulbous cartilaginous trunk traversed by a peculiar network of canals, in the singular
shortening of the vertical main-axis, and prolongation of the horizontal transverse axis.
Upon this vertical depression of the trunk depends the peculiar development of the
densely crowded cormidia. But the most striking peculiarity is the extraordinary
development of the swimming apparatus, the voluminous pneumatophore, the powerful
horizontal corona of radially expanded nectophores, and particularly the singular
aurophore, wanting in all other Siphonophorse, and acting probably as an important
gas-secreting gland or a pneumadenia. All these striking characters together make it
very probable that the Auronectse are permanent deep-sea Siphonophorse, which may
move up and down within certain limits of depth, but never come to the surface.

REPORT ON THE SIPHONOPHOR^. 305

Order V. CYSTONEOLE, Haeckel, 1888.
(Pis. XXII.-XXVI.)

Pneurnatophoridx, Chun, 1882, 86, p. 1168.
Cystonectse, Haeckel, 1888, 95, p. 44.

Definition. — Siphonophorae with a large apical pneumatophore, without nectophores
and without bracts. Nectosome represented only by the pneumatophore, which always
bears an apical stigma. Siphosome either a single cormidium with one siphon
(Monogastricae), or a tubular or vesicular trunk which bears numerous cormidia
(Polygastricse) Gonodendra always monostylic, provided with gonopalpons.

The order Cystonectae comprises all Siphonanthae which possess neither nectophores
nor bracts, the only organ of swimming being the large apical pneumatophore. They
differ in this respect from the three preceding orders, and agree with the Disconanthse or
Disconectse ; but the structure of the float, as well as the entire organisation, is in
these latter perfectly different (compare above, pp. 25, 26). We unite in the order
Cystonectae five different families, three of which are new, viz., the monogastric Cystalidae
and the polygastric Epibulidse and Salacidse ; the two other families, formerly known, and
both polygastric, are the Rhizophysidae (usually united with the Physonectae) and the
Physalidse ; these two families have been united by Chun, in 1882, under the name
Pneumatophoridse (86, p. 1168). All known Cystonectae agree in the complete
absence of nectophores and bracts, and in the possession of a large pneumatophore of
peculiar structure, provided constantly with an apical stigma for the emission of air.
All the genera of this order agree further in the peculiar composition of the monostylic
gonodendra, the gynophores of which are detached from the trunk before ripening. In
most other respects the Cystonectae agree generally with the Physonectaj ; they may be
derived from this order by the loss of the nectophores.

History. — Eschscholtz in his fundamental work (1) described, in 1829, three genera
and six species of Siphonophoras which belong to our order Cystonectae, viz., (l) the
Mediterranean Rhizophysa filiformis, Lamk. (described already in 1775 by Forskal, 11,
as Physophora filiformis), and the closely allied Rhizophysa planostoma, Peron (14, pi.
xxix. fig. 3) ; (2) the Australian Epibulia chamissonis (figured in 1821 by Eysenhardt,
77, as Rhizophysa chamissonis); and (3) the well-known interesting genus Physalia with
three species (the Atlantic Physalia caravella, the Indian Physalia pelagica, and
the Pacific Physalia utriculus). Eschscholtz, as well as most following authors, united
these three genera of Cystonectae with the Physophoridae (our Physonectae).

Brandt, in 1835, relying on the excellent (unfortunately hitherto unpublished) figures
and descriptions of several new Cystonectae by Mertens, established for them two different

(ZOOL. CHALL. EXP. PART LSXVU. — 1888.) Hhhh 39

306 THE VOYAGE OF H.M.S. CHALLENGER.

subfamilies with four genera : (l) the Rhizophysidse (with Epibulia and Rhizophysa),
and (2) the Physalidse (with Alophota and Physalia, 25, pp. 33, 36). The same two
groups were accepted by Huxley, in his Oceanic Hydrozoa, 1859, as two separate
families of Physophoridse (9, p. 71).

Physalia, as the largest and most splendid of all Siphonophorse, well known to all
travellers and sailors in the Tropics, celebrated by its peculiar form and swimming
locomotion, its brilliant colours and dangerous poison, has provoked a voluminous
literature (compare Eschscholtz, 1, p. 159; Olfers, 79, p. 26; and Huxley, 9, p. 93).
But the greatest part of it is without scientific value, full of errors, and not supported
by accurate researches. Huxley rightly says, that " this department of zoological
literature makes one long for the advent of a Caliph Omar, and produces a sort of
unpleasant vertigo" (9, p. 99). Indeed, the knowledge of Physalia, although
examined and described by numerous observers, has remained very insufficient up to
our time.

I myself had an excellent opportunity of observing living Physalidse, as well as
Rhizophysidse, during my residence in the Canary Island Lanzerote, in December
1866, and in January and February 1867. Among thousands of large Physalia}, which
appeared at Christmas 1866 in the harbour of Arrecife, there were some interesting,
crestless, small, new forms, which are figured in PL XXVI. of this Report as Alophota
(jiltschiana and Arethusa challengeri. Pis. XXIII. and XXIV. reproduce the figures
of two new genera of Rhizophysidse (Cannophysa with ordinate cormidia, and Necto-
physa with loose cormidia, both sexually mature), which I had drawn from life in
Arrecife in January 1867. But more interesting, as types of new families, may be the
two remarkable forms of Cystonects which I observed in December 1881 and January
1882 in Ceylon, and which are figured in PI. XXII. as Cystalia monogastrica and
Epibulia ritteriana.

The collection of the Challenger contains a number of Physalias collected in different
parts of the Tropical Atlantic and Pacific, and besides some other Cystonects or frag-
ments of them. Among these is a very interesting deep-sea form, from the Tropical
Atlantic (Station 338), Salacia pjolygastrica (PL XXV.) ; it is the type of a new family,
intermediate between the Rhizophysidse and Physalidse.

Some other interesting new forms of Rhizophysidse, also inhabitants of the deep
sea, were described in 1878 by Studer as different species of Rhizophysa (40, Taf. i.);
they represent, in my opinion, two different genera, Aurophysa inermis and Linophysa
conifera. The large form described by Studer as Bathyphysa abyssorum belongs
probably to the Forskalida? (compare p. 248).

Some similar deep-sea forms, described recently by Fewkes (45), are too incomplete
and too insufficiently known to allow us to recognise their true position in the system.
Recently Chun has given some valuable contributions to our knowledge of the

REPORT ON THE SIPHONOPHOR^E. 307

Cystonectae. He united in 1882 the Rhizophysidae and Physalidae under the name
Pneumatophoridae, and separated them from the Physophoridae (our Physonectae) (86,
p. 1168). He pointed out as a common character the absence of nectophores and bracts,
and the peculiar structure of the gonodendra. Chun further published the first
accurate description of the peculiar structure of the pneumatophore in the Rhizophysidae
and Physalidae, and of the metamorphoses of the young Physalia (48, 83, pp. 529, 557,
574).

The five different families of Cystonectse which are described in the sequel, exhibit
interesting relations to simflar families among the Physonectae. The monogastric
Cystalidae correspond to the simple Athoridas. Two polygastric families with a very
prolonged tubular trunk have analogous representatives in both orders ; the Rhizophysidae
(with monogastric cormidia) are comparable to the Agalmidse, the Salacidae (with
polygastric cormidia) to the Apolemidae. Two other polygastric families possess a
shortened and inflated vesicular trunk of the siphosome ; of these the Epibulidae are
similar to the Discolabidae, and the Physalidae in some respects to the Anthophysidae ;
the peculiar secondary development of the gigantic pneumatophore, however, and its
consequences for their further divergent organisation, remove still more widely the
Physalidae from all other Siphonanthae.

Nectosome and Siphosome. — The two different main portions of the corm, swimming
and feeding portion, exhibit a very different relation in the various Cystonectae. The
nectosome, or the swimming body, is represented only by the large pneumatophore and
corresponds to the modified umbrella of the original medusome. The siphosome, on the
other hand, exhibits a different shape in the monogastric Cystalidae, and the polygastric
Cystonectae of the four other famdies ; it is composed in the Cystalidae (PI. XXII. figs.
1-5) of a single large siphon (the manubrium of the original medusome), and of various
organs budding from its base (a tentacle, a corona of palpons, and a gonodendron). The
single siphon of the Cystalidae corresponds to the axial trunk of the four other families ;
from its ventral side arise numerous cormidia by budding. These secondary cormidia,
composed of siphons, palpons, tentacles, and gonodendra, are sometimes ordinate, at other
times loose ; they are densely aggregated in the Brachysteliniae (Epibulidae, PI. XXII.
fig. 6; and Physalidae, PI. XXVI.), with a shortened and inflated vesicular stem ; they are
loosely scattered and separated by long internodes in the Macrosteliniae (Rhizophysidae,
Pis. XXIII., XXIV.; and Salacidae, PL XXV.), which possess a long tubular stem.
The nectosome and siphosome are usually separated by a constriction corresponding to
that portion of the original medusome on which the manubrium is inserted into the centre
of the subumbrella. Another structure, differing from that of all other Siphonophorae,
is exhibited by the peculiar Physalidae. The hypertrophic pneumatophore extends here
into the trunk of the siphosome, along its dorsal side, so that this side becomes the
superior, and the opposite ventral the inferior side.

:)0S THE VOYAGE OF H.M.S. CHALLENGER.

Cormidia. — The entire body represents in the monogastric Cystalidse (PI. XXII. figs.
1-5) a single cormidiuni, composed of a large central siphon with a single tentacle, and
at its proximal base (beyond the pneumatophore) a corona of palpons, and a single
gonodendron. This solitary cormidiuni is similar to that of the Circalidae and
Atliorida? (PI. XXL), but differs in the absence of nectophores and bracts. The four
other families are polygastric, and therefore composed of a variable number of cormidia.
These are sometimes ordinate, at other times loose. They exhibit a different shape
in the two subfamilies of Rhizophysidse, where the trunk is very long, tubular, and
articulate ; the cormidia are ordinate and separated by equal free internodes in the
Cannophysidse (PI. XXIV.), where each cormidiuni is composed of a single siphon with
its tentacle, and a single gonodendron at its base ; whereas the cormidia are loose in
the Linophysidse (PI. XXIII. ), where the gonodendra are detached from the siphons,
usually alternating with them regularly. The family Salaeicla? (PI. XXV.) is distinguished
by polygastric ordinate cormidia ; the long tubular stem bearing in regular free intervals
numerous equal cormidia, each of which is composed of several siphons (with tentacles)
and gonodendra. The shortened vesicular stem of the Physalida3 (PI. XXVI.) bears
clusters of loose cormidia, without regular arrangement ; the cormidia of the Epibulidse,
however (PL XXII. fig. 6), seem to be ordinate, similar to those of the Discolabidse.

Pneumatophore. — The hydrostatic apparatus or the swimming-bladder is in all
Cystonectse large, sometimes gigantic and larger than all the other parts of the body
together ; it is the more important, as it is the only organ of floating, the nectophores
being entirely wanting. In Physalia it attains unusual dimensions (one or two decimetres
and even more), and occupies a far larger volume than in any of the other Siphonophoree.
The general form of the pneumatophore is usually more or less ellipsoidal, ovate or
pyriform, sometimes more irregular, oblongish round. Its longitudinal axis is usually
not vertical (as in the majority of Physonectse), but more or less obliquely inclined,
and in Physalia nearly horizontal. The cavity of the pneumatocyst opens in all
Cystonectse by an apical stigma, or a permanent pore, by which the animal expels
the included gas at will, when it will sink down. I have observed this emission of
gas repeatedly in the Rhizophysidse, Epibulidse, and Physalidse.

Pneumatocodon. — The outer wall of the pneumatophore, which we call pneumatocodon
("Luftschirm"), is in all Cystonectse very thick and muscular, and capable of strong
contraction. The strongest muscles are the longitudinal or meridional fibres, which lie
immediately under the exoderm and diverge from the open apical pole to the equator,
and then converge from the latter to the basal pole. They form around the apical stigma
a strong musculus ddatator (like that of the pupil of the eye). But further the stratum
of circular muscles of the entoderm, which is antagonistic, and separated from the
former by the thick fulcrum, is well developed. It forms around the apical stigma
a strong sphincter, or a circular musculus orbicularis, which closes its opening completely.

REPORT ON THE SIPHONOPHOR^E. 309

Pneumatosaccas. — The invaginated portion of the apex of the trunk, which forms
the air-sac, hangs in all CystonectaB freely in the pericystic cavity, or the wide interval
between the inner and outer wall of the pneumatophore. These two walls are not connected
by radial septa, as in most Physonectse, and are united only on the margin of the apical
stigma. The uppermost portion of the air-sac, which surrounds this stigma, is usually
intensely coloured (mostly red or brown), or covered by a hemispherical pigment-cap
(mitra ocellaris). A ring-like constriction (the pylorus infundibuli, " Trichterpforte ")
separates incompletely the larger apical and the smaller basal portion of the air-sac.
The former is the pericystic sac, which secretes the chitinous pneumatocyst (or the
cuticular air-flask) ; the latter is the hypocystic infundibulum or the pneumatochone
(air-funnel, " Lufttrichter"), which together with the tapetum endocystale forms the
air-secreting gland, or the pneumadenia. The basal or inferior opening of the
pneumatocyst (opposite to the superior or apical stigma) is often surrounded by an
annular thickening of the cuticle, the annulus pylori (PI. XXII. figs. 7,8).

Pneumadenia. — The exodermal epithelium of the pneumatosac (or strictly speaking
of its basal portion), which secretes the gas filling the float, in all Cystonectae is a
gas-gland or pneumadenia of considerable size. It exhibits the simplest shape in the
monogastric Cystalidas (PI. XXII. fig. 5) ; it is here a spheroidal vesicle of thickened
glandular exoderm, which communicates by a proximal opening (the pylorus) with the
cavity of the pneumatocyst ; this simple " air-funnel " is very similar to that of the
Apolemidse among the Physonectse (50, Taf. xix. fig. 93). The pneumadenia of the
Physalidte, the largest of all, is originally of the same simple shape as in the
Cystalidse, but expands afterwards unilaterally, on the ventral side of the pneumato-
phore, and forms there a large circular or oblongish air-secreting plate (" Luftplatte,"
Chun, 83, p. 569) ; in Caravella maxima it reaches the extraordinary size of 100 to
150 mm. This peculiar growth along the ventral side of the float is effected by the
extraordinary expansion, which the air-sac reaches in the Physalidse, growing down-
wards into the cavity of the trunk, along its dorsal side ; and by the consequent
asymmetrical development.

The three other families (Rhizophysidae, Pis. XXIII. , XXIV.; Salacidse, PI. XXV.;
and Epibulidas, PI. XXII. figs. 6-8) agree in a peculiar structure of the pneumatophore
and differ essentially from the two preceding (Cystalidaa and Physalidse). The beginning
of the structure is the same as in the latter ; but afterwards the pneumadenia exhibits
a further very remarkable development, firstly in the endocystic tapetum, and secondly
in the hypocystic villi. The glandular exodermal epithelium of the primary spheroidal
pneumadenia (or the air-funnel) grows in apical direction, passes through the pylorus
into the cavity of the pneumatocyst, and expands into its basal portion, lining its inside
(in younger floats only one-third, in older more than two-thirds). The extraordinary
development of the gas-gland in these CystonectaB corresponds to its important physio-

010 THE VOYAGE OF H.M.S. CHALLENGER.

logical function, since these Siphonophorse, which have no nectocalyces, descend into the
depths of the ocean by expelling the gas, and ascend again by secreting gas and filling the
float. We call this important new portion of the pneumatosac, which lines the inside
of the air-flask (excepting its apical portion), tapetum endocystale ("Secundaeres
exoderm," Chun, 48, pp. 514, 530).

Hypocystic Villi. — The second peculiarity which distinguishes the air-sac of the
Rhizophysidse, Salacidse, and Epibulidae, is the production of peculiar hypocystic villi
(PL XXII. figs. 6-8, pv; PI. XXIV. figs. 1-6, pv; PI. XXV. figs. 1-3, pv). These
remarkable apophyses of the air-funnel were first described in the Mediterranean
Rhizophysa filiformis by Gegenbaur (7, p. 44, Taf. xviii. fig. 6, e) and by Huxley (9,
p. 6, pi. viii. figs. 14, 15); they occur not only in all Rhizophysidse, but also in
Salacia and Epibulia. From the hypocystic air-funnel, beyond the pylorus, arise eight
radial bunches of clustered villi, which fill up the basal portion of the pericystic cavity,
often more than half of it. The single villi, or the finger-shaped branches of the clustered
bunches, are composed of a single or a few gigantic exoderm-cells (1 to 2 mm. in
diameter) and of a ciliated epithelium of small entoderm-cells. Their function is probably
mechanical, as an elastic cushion to protect the delicate pneumadenia and prevents
its sudden compression. (Compare below the description of the float in the Rhizo-
physidse, and also Chun, 47, p. 404 ; 48, p. 529.)

Siphons. — The feeding polypi tes or siphons in all Cystonectse are relatively large, often
of an extraordinary size. The four different segments of the siphon, which we could
distinguish in most Physonectse and Calyconectse (peduneulus, basigaster, stomachus,
proboscis), are also recognisable in many Cystonectse, as in Cystalia (PL XXII. fig. 5) and
Salacia (PL XXV. fig. 5). They are not distinguished, or at least not sharply separated,
in most Rhizophysidse, where usually each siphon is a simple cylindrical or fusiform
tube, distally contractile and protractile, with strong muscular wall (PL XXIII. figs. 1, 2,
5; PL XXIV. figs. 1-3, s). Probably in all Cystonectse the stomach, or the digestive
middle part of the siphon, bears inside numerous hepatic villi, sometimes arranged in
longitudinal series; but rarely there occur continuous hepatic striae, as in Linophysa. The
glandular villi are often coloured brown or black by pigment-granules, especially in the
Physalidae (PL XXVI. fig. 6, sv). The stomach in these and in other Cystonectse is rather
distinctly separated from the proboscis, or the distal part of the siphon, without villi, with
thickened muscular wall. Its distal mouth-opening may be expanded in the form of a
large suctorial disc, usually of circular, more rarely of polygonal or quadrangular form.
The basigaster or the basal cavity (PL XXVI. fig. 6, sb) is usually not separated from the
stomach by a pyloric valve, and its exoderm is not strongly thickened ; it passes over into
the peduncle without a sharp boundary, and often this latter part is scarcely distinguishable.
But sometimes the peduncle of the siphon is rather long and thin (bp). The monogastric
Cystalidse (PL XXII. figs. 1-5) possess only a single large siphon. All other Cystonectaa

REPORT ON THE SJPHONOPHORjE. 311

are polygastric. The macrostelial Rhizopliysidae (Pis. XXIIL, XXIV.) bear a single
siphon in each cormidium, as also do the brachystelial Epibulidae (PI. XXII. fig. 6).
The Salacidae exhibit a bunch of several siphons in each cormidium (PI. XXV. figs. 1-4).
The Physalidae, finally, bear on the ventral side of the shortened vesicular stem a
crowded group of numerous loose and polygastric cormidia, with a large number of
clustered siphons ; often larger and smaller polypites intermingled and arising from a
common pedicle, but the smaller Physalidae (Alophota, PI. XXVI. figs. 2, 3), and the
young forms of the larger species, bear on the ventral side of the trunk a simple series of
ordinate monogastric cormidia.

Protosiphon. — In many Cystonectae (or perhaps in all ?) the primary manubrium of
the larval medusome remains functional as the " primary feeding polypite," or the
protosiphon. It is the single siphon in the Cystalidae. In all young Physalidae the
protosiphon, placed at the basal pole of the inflated trunk and opposed to the apical
stigma, forms an independent cormidium (PI. XXVI. figs. 2, 3, su) ; originally it is
separated by a wide interval from the ventral group of the secondary cormidia, which
arise on the ventral side of the trunk, and bear the metasiphons (or the secondary
polypites). The latter alone afterwards produce gonodendra, not the former. So also
in the Epibulidae the protosiphon seems to remain as the basal siphon at the distal end
of the trunk. Its comparison with the manubrium of the primary medusome, or the
larva of the Cystonectae (Cystonula, PI. XXII. figs. 1-4 ; PI. XXVI. fig. l), shows us
that the axial trunk of the polygastric corms is only the basal part of the modified proto-
siphon, widely inflated in the Brachysteliniae, extremely prolonged in the Macrosteliniae.

Palpons. — All Cystonectse possess a great number of palpons (tasters, hydrocysts, or
mouthless polypites). These are usually cylindrical or spindle-shaped tubes with a
very contractile muscular wall, and a pointed and closed distal apex, often coloured.
They occur in three different forms, as sexual palpons, coronal palpons, and tentacular
palpons.

Gonopalpons or Sexual Palpons are generally distributed, occurring in the gonodendra
scattered between the gonophores. Sometimes each branch of the clustered gonodendron
bears a single gonopalpon (PL XXIIL fig. S,gq); at other times several palpons (PL XXV.
%• 7> gq); those of the Physalidae (PL XXVI. fig. 8, q) are distinguished by the
possession of hepatic villi, which prove evidently that they are merely mouthless siphons.

Coronal Palpons occur only in two families of Cystonectae, in the monogastric
Cystalidse and the polygastric Epibulidae (PL XXII. figs. 5, 6). They form a corona
around the base of the siphosome, beyond the pneumatophore, similar to that of the
Discolabidae and Anthophysidae (Pis. XL, XIX.). As in these latter, the coronal palpons
are not only organs of feeling and capturing, but also of protecting, and replace the
absent bracts. Their pointed distal end is armed with cnidocysts.

Tentacular Patyons are peculiar to one family only, the Physalidae (PL XXVI. figs.

312 THE VOYAGE OF H.M.S. CHALLENGER.

3-6, to), where each tentacle does not arise from the base of a siphon (as is usually the
case in the Siphonanthse) but from the base of a large palpon, which is connected by
a common pedicle only with the base of the siphon. Huxley, therefore, calls these
palpons not hydrocysts, but basal sacs of the tentacles (similar to the ampullae of
the ambulacral feet in Echinoderms). It may be that these basal ampullae are only
secondary diverticula of the base of the tentacle, and have the morphological value of a
subordinate organ. On the other hand, it is possible that each cormidium of the
Physalidse originally bore two polypites each with a tentacle ; one of these (the siphon)
has preserved the mouth and the hepatic villi, but lost the tentacle ; the other, conversely,
has lost the former organs and preserved the latter (the palpon).

Tentacles. — The capturing filaments are arranged in the majority of Cystonectse in
the same manner as in all other Siphonanthse, a single tentacle arising from the basal
pedicle of each siphon. A single exception is formed by the Physalidse, in which the
tentacles arise from the base of peculiar palpons, as has just been mentioned (PL XXVI.
figs. 2-6). The tentacles are generally long and vigorous, very muscular tubules,
sometimes simple, at other times branched. They are simple, not branched filaments in
the genera Linophysa (Rhizophysidse) and Salacia (Salacidse), and in all Physalidse.
In all the other genera the tentacles are branched, and bear, usually, a single series of
equidistant tentilla or lateral filaments. These latter are simple thin tubules, beset with
scattered cnidoblasts in the genera Cystalia, Epibulia (PL XXII.), Aurophysa, and
Nectophysa (PL XXIII. ). The distal end of the tentillum is trifid (with a terminal
ampulla and a pair of lateral horns) in the genera Cannophysa (PL XXIV.) and
Pneumophysa. The genus Rhizophysa is distinguished by the possession of two or three
different kinds of tentilla ; between the trifid forms being intermingled peculiar large
hand-shaped or palmate tentacles which bear an ocellus.

The cnidocysts of the tentacles are spherical in most Cystalidse (PL XXI II. fig. 7), and
do not exhibit that variation in form seen in the Physonectse. Their arrangement is
variable in the various groups. Usually each tentillum bears a multiple series of cnido-
cysts on its dorsal side whilst the opposite ventral side is covered with palpoblasts
(PL XXIII. fig. 6, tw). The simple tentacles of the Physalidse (PL XXVI. fig. 6, t) and
of the Salacidse (PL XXV. fig. 5, t) bear a long series of large reniform cnidonodes on
their dorsal side (compare Huxley, 9, pi. x. figs. 11, 12, &c). Each cnidonode embraces
the tentacle with the concave ventral side, and bears on the convex dorsal side a cushion
of cnidocysts. They develop in the same manner as the tentilla of branched tentacles
and contain a cavity, as a diverticulum of the tentacular canal. Each kidney-shaped
cnidonode, therefore, may be regarded as a very short and broad tentillum.

Gonophores. — All Cystonectse possess monoecious corms, monoclinic cormidia, and
monostylic gonodendra, male and female gonophores arising from the same branched
gqnostyle. The peculiar form and composition of the clustered gonodendra seems to be

REPORT ON THE SIPHONOPHOR^E. 313

the same in all members of this order. The stem of the gonostyle is always richly
ramified, and bears on each branch one or several sexual palpons (gq), a single gynophore
or female medusome (f); and a great number of androphores or male medusomes (h).
These latter become mature whilst attached to the gonodendra ; they have ovate or
club-shaped spermaria, with a more or less rudimentary umbrella (PI. XXIII. fig. 8, h;
PI. XXV. fig. 7, h; PI. XXVI. fig. 8,h).

The larger female gonophores, however, are probably always detached in the im-
mature state from the stem, and become mature as free Anthomedusse. Their
umbrella (f in the figures quoted) is well developed, campanulate or pyriform, with four
radial canals and a ring-canal, and a broad velum around the ostium. The manubrium,
in the wall of which the eggs ripen, seems to be developed usually after the detachment.
It is not visible in the sessde gynophore, or forms only a small tubercle in the centre of
the subumbrella (PI. XXIII. fig. 8,fm). The apex of the gynophore is attached to the
branch of the stem by a large conical pedicle (PI. XXIII. fig. 8, f). These pedicles
remain attached to the stem of the gonodendron, when the ripe gynophores are detached.
Some very large specimens of Caravella maxima, which I observed in the Bay of Alge-
siras (Straits of Gibraltar), in March 1867, bore voluminous gonodendra, the androphores
of which were filled with ripe sperm. Some of their numerous branches possessed each
a single medusiform gynophore (PI. XXVI. fig. 8,f), whdst in other branches only its
conical pedicle was visible, the campanulate umbrella having been detached (compare
Chun, 86, p. 1168).

The Cystalidae, Epibulidas, and Rhizophysidse seem to possess on each branch of the
gonostyle a single sexual palpon only, corresponding to the single gynophore (PI. XXIII.
fig. 8) ; whilst the Salacidse and Physalidse bear several gonopalpons on each branch.
The gonopalpons of the Physalidse are covered inside by the same black hepatic villi as the
siphons, and thus prove to be modified mouthless siphons (PL XXVI. fig. 8, q). The
sexual tasters of the Rhizophysidse are often covered outside with peculiar cnidonodes
(PI. XXIII. fig. 8, gq).

Ontogeny. — The development of the Cystonectse from the fertilised egg is up to
this time quite unknown. The ripe eggs themselves have never been observed. The
medusiform gynophores are detached early from the trunk, and the special forms of
Anthoniedusas, in which they produce ova, are not yet known. Very little is known
also of the monogastric larvae of the Cystonectse (Cystonula), and of their peculiar
metamorphosis. Those of Physalia were first described by Huxley (9, p. 102, pi. x.
figs. 1,2) and afterwards by Chun (83, p. 558). The Cystonula of the other families is
hitherto unknown. Some light, however, may be thrown upon this complete darkness by a
number of larval forms which I captured by means of the tow-net in December 1881, in
Ceylon, and which are figured in PI. XXII. figs. 1-4. Compare their description below,
under that of the family Cystalidae (p. 315).

(ZOOL. CHALL. EXP. — PART LXXVU. 1888.) Hhhll 40

314

THE VOYAGE OF H.M.S. CHALLENGER.

Synopsis of the Families of Cystonectse.

I. Suborder Cystonectje monogastric^: (Monostelinije).

Corm with a single large siphon, representing one cormidium only. A single tentacle
on the base of the siphon. A corona of palpons around the base of the large pneu-

matophore. Pneumatosac without hypocystic villi,

A. Maceostelinle.

II. Suborder

Cystonecm:
polygastrioe.

Corm composed of numer-
ous cormidia, each with
one or more siphons and
tentacles. Cormidiasome-
times ordinate, at other
times irregular. (Primary
larva monogastric, Cysto-
nula.)

Trunk of the siphosome ,
very long and thin,
tubular, with prolonged
internodes.

B. Brachystelini^:.

Trunk of the siphosome
short and wide, vesicular
or bag-shaped, with short
ened internodes.

Cormidia monogastric, each
with a single siphon and
tentacle. (Pneumatosac
with hypocystic villi),

Cormidia polygastric, each
with several siphons and
tentacles. (Pneumatosac
with hypocystic villi),

Cormidia in a spiral corona
around the vesicular trunk,
beyond the base of the
subvertical pneumatophore
(with hypocystic villi),

Cormidia in a multiple series
along the ventral side of
the trunk, the dorsal side
of which is occupied by the
subhorizontal pneumato-
phore (without hypocystic
villi), .

20. Cystalid*.

21. Rhizophysids.

22. Salacidw.

23. Epibulidfe.

24. Physalida?.

Family XX. Cystalid.e, Haeckel, 1

Cystalidx, Hkl., System der Siphonophoren, p. 44.

Definition. — Cystonectse nionogastricse, with a single large siphon and a single
tentacle on the base of the large apical pneumatophore. Base of the siphon surrounded by
a corona of palpons. Pneumatosac simple, without radial septa and hypocystic villi.

The family Cystalidse comprises a single new genus of small, but very remarkable
Cystonectse, which differs from all other genera of this order in the monogastric structure
of its corm. This interesting genus, Cystalia (PL XXII. fig. 5), exhibits therefore a
relation to all the other potygastric Cystonectse similar to that which the monogastric
Circalia or Athoria (PI. XXI.) bears to the polygastric Physonectse.

During my residence in Ceylon I captured by the tow-net several times the elegant
form, which I called in my System (95, p. 44) Cystalia larvalis. A very similar, and
perhaps identical, form was found in a bottle of the Challenger collection, from Station
288 (centre of the Southern Pacific); I named it there Cystalia challengeri. A closer
comparison of them makes it very probable that these two species are identical ; the
more significant name Cystalia monogastrica may, therefore, be retained for both.

At the first glance I had supposed that Cystalia larvalis might be only a young form

REPORT ON THE SIPHONOPHORiE. 315

or a monogastric larva of the polygastric Epibidia ritteriana (PI. XXII. figs. 6-8).
Indeed it is possible that this latter has been developed immediately from the
former, or that Cystalia is a larva of Epibulia, which has reached sexual maturity only
exceptionally (Pedogenesis). But comparing the structure of the pneumatophore in both
similar forms, we find that the polygastric Epibulia possesses the eight radial clusters of
hypocystic villi characteristic of the Rhizophysidae, whilst these are wanting in the
monogastric Cystalia. In any case the fully developed state of the gonodendron in
the latter justifies its position as an independent genus.

In the same month (December 1881) in which I captured Cystalia larvalis off the
coast of Ceylon, I took by the tow-net a number of young larvse of Siphonanthas,
which I supposed at the first glance to be the larvae of some Physonect, perhaps
an Agalmid. The most important stages of them are figured in PI. XXII. figs. 1-4.
Comparing them with the larvse of the Agalmid Cupulita, which Metschnikoff has
described as Stephanomia pictum (85, Taf. xii.), we find a great likeness between these
larvse. The youngest larva observed (fig. 1) exhibits a spindle-shaped gastrula,
composed of a large-celled entoderm (cl) and a small-celled ciliated exoderm (e), with
the invagination of the pneumatophore on the apical pole. In the second stage (fig. 2)
the medusiform body is divided by a transverse annular constriction into a proximal and
a distal portion ; the superior portion is the rudimentary umbrella with the pneumato-
phore (already containing a gas-bubble) ; the inferior portion is the primary siphon, from
the base of which arises a single tentacle. In the third stage (fig. 3) the distal mouth of
the siphon is open, and from its base, opposite to the dorsal tentacle, arises in the
ventral side the first bud (i), probably of a palpon. The fourth and last stage observed
(fig. 4) exhibits the number of buds augmented (as the beginning of a corona of
palpons ?), and the single tentacle beset with a series of simple filiform tentilla (ts).

Since I was not able to recognise the origin of these pelagic larvse, nor to follow
their further development, the question remains open, whether they were produced by a
Physonect or a Cystonect. In the latter case they may possibly have been derived
either from Cystalia or from the closely allied Epibulia.

Cormidium. — The central or axial portion of the single cormidium, which represents
the entire adult corm of Cystalia, must be regarded as an individual medusome, the
modified umbrella of which is the pneumatophore (p) and the manubrium the siphon (s).
The base of this latter bears a single tentacle on its dorsal side, a single large gonoden-
dron (gd) on its ventral side. The short tubular pedicle of the siphon which connects it
with the base of the float represents the axial trunk of the corm, and has produced by
budding the corona of palpons, which are expanded between them. The gonodendron
itself is the sexual portion of the single cormidium, composed of numerous male and
female gonophores, each of which is a modified medusome.

Comparing the single parts of the corm with the similar parts of related Siphono-

316 THE VOYAGE OF H.M.S. CHALLENGER.

phorse, we find resemblances to different families. The pneumatophore resembles by its
simple structure that of the Athoridse and Apolemidse, and that of the young Physalidse
(Alophota, PI. XXVI. figs. 1,2); the pericystic cavity is simple and has not the radial
pouches of most Physonects, nor the hypocystic villi of the Rhizophysida? and Epibulidse.
The corona of palpons between float and siphon is similar to that of Epibulia (PI. XXII.
fig. 6), and also to that of the Discolabidre and Anthophysidse. The single tentacle, with its
series of simple filiform tentilla, resembles that of Epibulia and Nectophysa (PI. XXII.
figs. 5,6). The structure of the single siphon, with its hepatic villi, and of the monoclinic
gonodendron, is the same as in the Rhizophysidre and Physalidae.

Genus 65. Cystalia,1 Haeckel, 1888.
Cystalia, Hkl., System der Siphonophoren, p. 44.

Definition. — Oystalidge with a tentacle, which bears a series of simple filiform tentilla.
A single large monostylic gonodendron is attached to the base of the single siphon.

The genus Cystalia, as the only known form of monogastric Cystalidse, exhibits
the peculiar structure described above of this family. Supposing that other genera,
belonging to it, may sometimes be observed, we assume as a generic character of Cystalia
the structure of the single tentacle, which is similar to that of Aurophysa, Nectophysa,
and Epibulia. It bears a series of simple lateral branches, which remain cylindrical
filaments, without terminal appendages. On the medusiform larva? (Cystonula, PI.
XXII. figs. 1-4), which may perhaps belong to this genus, compare p. 315.

Cystalia monogastrica, n. sp. (PI. XXII. figs. 1-5).

Cystalia larvalis et Cystalia challengeri, Hkl., 95, p. 44.

Habitat— South Pacific; Station 288, October 21, 1875; lat. 40° 3' S., long.
132° 58' W.; surface.

Indian Ocean, Ceylon, Belligemma, December 1881 (Haeckel).

Corm (fig. 5). — The monogastric corm, represented in fig. 5 in the expanded state,
has a length of 10 to 12 mm. It is to be regarded as a single cormidium, composed of
a sterile axial medusome and two groups of peripheral medusomes, sterile palpons and
fertile gonophores. The large axial medusome consists of a pyriform pneumatophore
and a large spindle-shaped siphon, with a single tentacle ; the siphon corresponds to the
manubrium, and the float to the modified umbrella of the original Medusa. The short
pedicle of the siphon, which connects it with the base of the float, may be regarded as
the axial trunk of the corm, from which the corona of palpons as well as the large ventral

: Cystalia = Sea-bladder, xvarn, s"a<«.

REPORT ON THE STPHONOPHOR^. 317

gonodendron are produced by budding. Each branch of the gonostyle is a secondary
cormidium, composed of a sterile distal palpon, a large female medusome, and a group of
clustered small male medusomes.

Pn&muxtophore (fig. 5, £>). — The float is pyriform, 3 mm. long and 2 mm. broad,
with a red pigment-cap in the apical third. The enclosed pneumatocyst is subspherical,
1*2 to 1*5 mm. in diameter; it fills the upper or apical portion of the air-sac, which is
separated by an annular diaphragm (pylorus infundibuli) from the spheroidal lower or
basal portion, the air-funnel. This is lined by the greenish hypocystic tapetum, which
also enters by the pylorus into the cavity of the air-flask and lines its basal third as
endocystic tapetum. No radial septa or villi arise from the air-funnel.

Siphon (fig. 5, s). — The single siphon of the monogastric cormidium is spindle-shaped,
6 to 9 mm. long and 2 to 3 mm. broad. Its ampullaceous basal portion (basigaster) is
attached by a short pedicle to the base of the pneumatophore. The dilated middle
portion, or the stomach, is covered inside with numerous yellowish-brown hepatic villi
(sh). The thin tubular proboscis (sr) is very muscular and opens by a mouth, which
may be expanded in the form of a circular suctorial disc (ss).

Tentacle (fig. 5). — The single tentacle (t) which arises from the base of the siphon,
on its dorsal side, is a slender cylindrical tube, beset with a series of tentilla. These
are simple cylindrical filaments, and bear on their dorsal side a multiple series of cnido-
cysts ; the structure is similar to that of Nectophysa (PI. XXIII. figs. 5, G).

Palpons (fig. 5). — The corona of rose-coloured tasters which protects the siphosome
is attached to its base, immediately beyond the nectosome. It is composed of about
thirty spindle-shaped palpons, besides the small buds of young ones. Their pointed
distal end is closed, whilst the proximal end of their cavity communicates with the
pedicular canal of the siphon.

Gonodendron (fig. 5, gd). — The single large clustered gonodendron, which is attached
to the base of the siphon, on its ventral side, is similar to that of the Rhizophysidse.
The gonostyle is richly branched, and each ultimate branch bears a single gonopalpon on
its distal end (PI. XXIII. fig. 8, gq), and above it a single medusiform gynophore (/)
and a cluster of several (four to eight) ovate androphores (h).

Family XXI. Rhizoph ysice, Brandt, 1835.

Rhizophysidx, Brandt, Prodromus descriptionis, &c, 25, p. 33.

Definition. — Cystonectse polygastricse, with a long tubular trunk of the siphosome,
bearing in its ventral median line numerous monogastric cormidia, separated by free
internodes. Each cormidium with a single siphon and a single tentacle. Pneumato-
saccus large, without radial septa and pericystic radial pouches, but with eight or
more radial groups of hypocystic villi.

318 THE VOYAGE OF H.M.S. CHALLENGER.

The family Rhizophysidae comprises all Cystonectae polygastricse with a long tubular
stem, bearing numerous monogastric cormidia. The trunk of the conn is a prolonged and
very contractile tube, as in the succeeding Salacidse ; but the cormidia of these latter
are polygastric. Many different species, and mainly deep-sea forms of gigantic size,
seem to belong to this interesting family ; but only a few species have been described
hitherto with sufficient accuracy. All species have been united up to this time in a
single genus, Rhizophysa.

The oldest known form of Ehizophysidae is the Mediterranean Rhizophysa filiformis,
described as early as 1775 by the first author on Siphonophorse, Forskal, under the name
Physophora Jiliformis (11, p. 120, Tab. xxxiii. fig. F). A similar species from the
Atlantic was figured in 1807 by Peron and Lesueur under the name Rhizophysa
planostoma (14, pi. xxix. fig. 3). A third species of the same genus was observed in
1827 by Mertens in the Northern Pacific, and described by Brandt in 1835 as Epibulia
mertensii (25, p. 33). Unfortunately Mertens' excellent figure, drawn from life and
exhibiting distinctly the characters of the genus Rhizophysa, has never been published.
Brandt established for these forms the family Ekizophysidaj (loc. cit., p. 33).

The first accurate anatomical description was that given in 1854 by Gegenbaur of
the Mediterranean Rhizophysa Jiliformis (7, p. 324 ; 10, p. 78). It was afterwards
supplemented by Huxley (9, p. 90), Fewkes (41, p. 292), and especially by Chun (47,
p. 404; 48, p. 529; 86, p. 1169). Two new genera of this family, Cannophysa and
Nectop>hysa (Pis. XXIIL, XXIV.), were observed by me in 18(56 off the Canary Islands.
Two other genera, Aurophysa and Linophysa, both inhabiting the deep sea, were
described in 1878 by Studer as species of Rhizophysa (40, p. 4, Taf. L).

Truncus. — The common stem of the corm is in all Rhizophysidae a very long and
slender cylindrical tube ; its contractility is so great that, in the expanded state, it
may be ten to twenty times as long as in the contracted state (compare PI. XXIIL
figs. 1-3 and PL XXIV. figs. 1-3). At the same time it is so sensitive that a slight
touching of the stem is sufficient to effect suddenly its strongest contraction. The
wall of the tubular trunk is rather thick, with a thin layer of circular muscles arising
from the entoderm, and a thick layer of longitudinal muscles arising from the exoderm ;
the latter are arranged, as usual, in parallel bundles along the radial folds of the
fulcrum, which separates the two layers. The exoderm is often coloured yellowish, rose,
or brown.

Cormidia. — The numerous cormidia, which arise from the long tubular stem of the
corm, exhibit in the Rhizophysidae (as in the Agalmidae) a double shape and arrange-
ment, according to which two subfamilies may be separated, the Cannophysidae and
Nectophysidae. The Cannophysidae (PI. XXIV.) possess ordinate cormidia, which are
separated by long, free, and naked internodes of equal length (similar to those of the
Stephanomidse) ; each cormidium is composed of a siphon, a tentacle, and a gonostyle ;

REPORT ON THE SIPHONOPHOR^E. 319

this latter is branched and bears numerous clustered gonodendra, each of which is again
composed of a gonopalpon, a large female gonophore, and a variable number of smaller
male gonophores. The Nectophysidse, on the other hand (PI. XXIIL), have loose cormidia
(simdar to those of the Halistemniidse) ; the gonostyles are not attached to the trunk
at the basal insertion of the siphons, but separated from them on the internodes ; some-
times a single gonodendron in the middle between each two siphons {Nectophysa, &c),
at other times two to four or more gonodendra.

Pneumatophore (PL XXIII. figs. 1-4, p ; PL XXIV. figs. 1-7, p).— The float filled
with air is in all Rhizophysidse relatively large, much larger than in the Physonectae ;
its form is variable, usually ovate, ellipsoidal or pyriform. Its central axis is sometimes
vertical, usually more or less incbned, at other times almost horizontal. The pneumato-
codon, or the outer wall of the float (p), is separated from the pneumatosaccus, or the
inner wall, by a wide cavity, which often occupies nearly the half of the pneumato-
phore, or even more. This pericystic cavity is closed above (where the two walls of the
float are connected on its top), and opens below into the axial canal of the trunk ; its
greater part is filled up by clusters of large branched villi, the radial apophyses of the
pneumadenia.

Pneumatosaccus. — The invaginated part of the exoderm, which we call pneuma-
tosac, hangs freely in the pericystic cavity, and is not connected with it by
radial septa (as in most Physonectse). It is connected with the pneumatocodon
only at its top, where it opens by the apical stigma (po). The simple wall of the
young pneumatosac (comparable to the invaginated entoderm of a gastrula) is divided
in the adult Rhizophysidse into five different parts, viz.: — (1) A mitra ocellaris or an
apical pigment-cap ; (2) the pericystic sac, enclosing the air-flask ; (3) the hypocystic
funnel ; (4) the hypocystic radial bunches of villi arising from the funnel ; and (5) the
endocystic tapetum ("secondary exoderm"). This latter lines the greater part of the
inside of the chitinous pneumatocyst.

Pneumatocyst. — The chitinous air-flask or pneumatocyst is originally the cuticle
of the young pneumatosac. It is ovate, spindle-shaped or cylindrical, and opens at
both poles of its longitudinal axis ; the inferior opening is the pylorus infundibuli,
which leads into the funnel-cavity of the pneumadenia ; the superior opening is the
apical stigma, through which the air may be emitted at wfll from the cavity of the
pneumatocyst (PL XXIII. fig. 3, x). This stigma, or the apical opening of the float
(PL XXIV. figs. 4, 5,po), may be opened by a corona of radial muscles (pn) and closed
by a sphincter composed of ring-muscles (pm).

Mitra ocellaris. — The pigment-cap of the float, or the mitra ocellaris (PL XXIII.
fig. 3,pp; PL XXIV. figs. 4, 5,2^p), occupies sometimes nearly the upper half, at other
times only the uppermost third or fourth of the pneumatosac, and is composed of elegant
polygonal pigment-cells, separated by colourless intervals. The colour is usually red or

320 THE VOYAGE OF H.M.S. CHALLENGER.

brown, sometimes more orange, at other times more violet or even black. The inferior
margin of the hemispherical or campanulate pigment-cap is usually separated by a
sharp circular boundary-line from the colourless or yellowish middle portion of the
air-sac (PI. XXIV. fig. 5, pp).

Sacculus pericystalis. — The greater middle part of the pneumatosac is a simple
layer of exodermal epithelium, and produces the pneumatocyst as a true cuticle ; it
ends, together with this latter, on the pylorus infundibuli, or the opening by which the
air-flask communicates with the funnel-cavity; the terminal edge of the cuticle which
surrounds this circular pylorus is usually a thickened chitinous ring (annulus infun-
dibuli).

Pneumatochone (infundibulum pneumatophori, " Lufttrichter," Chun, 48, p. 512). —
The distal or basal part of the original pneumatosac situated below the pylorus is the
important pneumatochone or the " hypocystic funnel." The thickened glandular
epithelium which lines its cavity is very different from that of the pericystic sac. It
produces no cuticle, but is composed of several layers of polyhedral exoderm-cells,
which have a rather dark granular protoplasm and a peculiar yellowish or more greenish
appearance (PI. XXIV. fig. 7). From this ovate, hemispherical, or nearly spheroidal
" air-funnel " arises inside, the endocystic tapetum, and outside, the clustered groups of
hypocystic villi (PL XXII. fig. 7).

Tapetum endocystale ("secondary exoderm," Chun, 48, pp. 514, 530). — The exo-
dermal tapetum which lines inside the basal half of the pneumatocyst (in young
Bliizophysidge the basal third, in adult more than two-thirds) is the direct continuation
of the hypocystic funnel, and its function is, like that of the latter, the secretion of gas ;
both together represent the " pneumadenia," or the gas-secreting gland. The stratified
exoderm of the air-funnel grows upwards, passes through the chitinous ring of the
funnel-pylorus into the cavity of the pneumatocyst and lines the greater part of its
inside, with the exception of the apical part which is covered by the mitra ocellaris. The
endocystic tapetum is composed of several strata of the same peculiar granular and
yellowish or greenish exoderm-cells, as those which line the funnel-cavity and are
polyhedral by mutual compression (PI. XXII. fig. 7,pd; PI. XXIV. fig. 7,pd).

Villi hypocystales (PI. XXIV. figs. 4, 5, pv, 6). — The basal portion of the
pericystic cavity, and often its greater part (with the exception of the apical portion), is
filled with bunches of clustered villi, which arise from the outside of the hypocystic
funnel. They were first described by Gegenbaur (in 1854) as " csecal diverticula " of the
pneumatocyst (" blinddarmiihnliche Fortsiitze," 7, p. 326, Taf. xviii. fig. 6, e). Huxley
(in 1859) described them as "elongated and more or less branched processes, which
project from the distal surface of the pneumatocyst freely into the cavity of the
pneumatophore ; each process consists of a cellular axis, invested by the ciliated
entoderm. The cells of the axis are clear and very large, and have an opaque oval

REPORT ON THE SIPHONOPHOR^E. 321

nucleus" (9, p. 6, pi. viii. figs. 14, 15). This good description of Huxley was not
improved by later authors, who regarded the hypocystic villi as tubes or utriculi.
Fewkes (in 1882) describes them as " finger-like pouches, which are sometimes bifurcated
at their extremities and open at their distal ends, so that their cavities seem to
freely communicate with that of the float" (44, p. 269, pi. vi. fig. 2). The most
accurate description was afterwards given by Chun, who regards their physiological
function as mechanical ; they may serve as elastic cushions or bolsters, which protect
the delicate pneumadenia covered by them, and prevent its sudden compression, when
the stem is rapidly contracted (47, p. 404 ; 48, p. 529). My own observations on
the structure and development of these interesting villi, made in Lanzerote (1867),
and continued in Ceylon (1881), are in complete accordance with those of Chun. The
hypocystic villi are always arranged in eight radial bunches which arise from the outside of
the air-funnel ; each villus, or each finger-like branch of the dichotomously-branched villi,
consists of a single giant-cell, or a few (two to four, rarely more) giant-cells, which reach
a diameter of one to two millimetres, and belong, therefore, to the largest cells of animal
tissues ; the nucleus of these vesicular and vacuolated exoderm-cells is ovate or cup-
shaped, and has a diameter of O'l to 0"2 mm. The surface of the villi is covered with a
vibratile epithelium, comjjosed of small entoderm-cells with long cilia (PI. XXIV. fig. 6).
In the youngest Rhizophysidge there are only eight single club-shaped giant-cells, which
arise from the pylorus infundibuli ; they correspond to the base of the eight radial
apophyses of the air-funnel, which pass into the radial septa dividing the cavity of the
pneumatophore into eight radial pouches in many Pkysonectse (e.g., Discolabidse, compare
above, p. 187). Afterwards arises a second corona of eight radial giant-cells from the
distal base of the hypocystic funnel, and a third corona between the former and the
latter (48, p. 530). By dichotomous ramification of these twenty-four giant-cells and
further development of lateral branches arises the large elastic cushion, composed of
numerous finger-like villi, which envelops in the adult Rhizophysidge the greater part of
the pericystic cavity and hangs down into the apical part of the stem-canal (PI. XXIII.
figs. 3, 4 ; PL XXIV. figs. 4, 5).

Sijyhons. — The feeding polypites are in the Rhizophysidse usually of considerable size,
sometimes very large, 4 to 8 centimetres long, or more, in the expanded state. The four
segments of the siphon which are usually distinct in the majority of Siphonophorse are
rarely evident in this family ; in the majority they are not distinct or not recognisable at
all, so that the whole siphon is a simple cylindrical or spindle-shaped tube (PI. XXIII.
fig. 5; PI. XXIV. figs. 1-4). Sometimes, however, especially in the peculiar Liuophysa,
the four segments are distinctly marked: — (1) A small pedicle to which the tentacle
is attached ; (2) a large ovate basigaster, the exoderm of which is full of cnidocysts ;
(3) a wide stomach with coloured hepatic glands ; and (4) a very contractUe tubular
proboscis, with the tubular mouth-opening (40, p. 9, Taf. i. fig. 4). The thick wall of

(ZOOL. CHALL. EXP. — rART LXXVII. — 1888.) Hhhh 41

322 THE VOYAGE OF H.M.S. CHALLENGER.

the tubular siphon is always very extensible and contractile, provided with strong longi-
tudinal and circular muscles. The entoderm of the stomach usually bears very numerous
and small hepatic villi, containing pigment-granules and clear glandular vacuoles ; rarely
the hepatic glands are arranged into eight or sixteen longitudinal series, and form
coloured " liver-ridges," as in Linophysa. The distal mouth is always very dilatable, and
may be expanded in the form of a large circular suctorial disc (PI. XXIII. fig. 5 ;
PL XXIV. fig. 1).

Tentacles.— The long tubular tentacle which arises from the base of each siphon, on
its superior or dorsal side, is rarely a simple, unbranched filament, similar to that of
Apolemia, as in Linophysa (40, Taf. i. fig. 1). In all other known genera it is beset with
a series of numerous equidistant tentilla or unilateral branches. These tentilla exhibit
in the various genera of Rhizophysidse similar differences in form and structure to those
seen in the Agalmidse among the Physonectas, although a true cnidosac (as in the latter) is
not developed. The tentilla are simple tubular filaments, with a unilateral series of cnido-
cysts, in Aurophysa and Nectophysa (PL XXIII. figs. 1-6); usually the axial or ventral side
of the tentillum is beset with several rows of sensitive palpoblasts (fig. 6, tw), the abaxial
or dorsal side with some series of spherical cnidoblasts (fig. 6, kc). The genera Canno-
physa and Pneumophysa are distinguished by trifid tentilla (PL XXIV. figs. 8, 9) ;
their distal end bears an odd terminal vesicle (fig. 9, ta) and two paired lateral
horns (fig. 9, tc) ; these are armed in different ways with cnidonodes or roundish
groups of spherical cnidocysts. Rhizophysa, finally, is distinguished by the compound
structure of the tentacles which bear two, three, or more different kinds of tentilla ;
these are partly simple, partly trifid or branched ; and usually there are scattered between
them a small number of very large and remarkable appendages, first described in
the Mediterranean Rhizophysa filiformis by Gegenbaur (7, Taf. xviii. figs. 7-9). They
are fiat, palmate, or hand-shaped leaves, dichotomously branched at the free distal
margin, each branch provided with a spherical cnidocyst. In the similar Atlantic Rhizo-
physa planostoma (Peron), I observed in December 1866 similar but larger appendages,
which bore in the middle of their upper or outer side a large purple ocellus ; a pigment-
ring with a strongly refracting globule in the centre. I suppose that this globule is a
lens, and the ocellus a true eye.

Gonostyles. — Each cormidium of the Rhizophysidse bears usually a single, clustered
and monoclinic gonodendron only; this is attached to the node of the stem, immediately
beyond the basal insertion of the siphon, in the ordinate cormidia of the Cannophysidse
(PL XXIV.) ; whilst it is attached to the internodes of the stem, between the siphons, in
the loose cormidia of the Linophysidse, where usually the siphons and gonodendra
alternate regularly, in equal numbers (PL XXIII. figs. 1-3); but sometimes the number
of gonodendra is augmented (in Rhizophysa), so that a variable number of gonostyles (two
to four or more) arises from the internode between every two siphons; in some species

REPORT ON THE SIPHONOPHORvE.

323

they are irregularly scattered. The gonostyle, or the axial stern of each gonodenclron, is
more or less branched, in the larger species with very numerous branches; each branch is
monostylic and exhibits the same structure (PL XXIII. fig. 8), as is common to all
Cystonectas (compare above, p. 313). The distal end of the branch bears a spindle-shaped
palpon with numerous cnidocysts (fig. 8, gq), and at its base a single large medusiform
gynophore (f) surrounded by a corona of club-shaped androphores (h).

Synopsis of the Genera of Rhizophysidte.

I. Subfamily Cannophysid;e.

Cormidia ordinate, separated by free internodes. Gono- -
styles attached to the stem immediately on the base of
the siphons.

Tentilla simple, not bran-
ched,

Tentilla trifid, with three
terminal branches.

II. Subfamily Linophysidjj.

Cormidia loose. Gonostyles
attached to the inter-
nodes of the stem, scattered
between the siphons.

f Tentilla wanting, tentacles
Tentacles simple, without I simple, .
tentilla ; or with simple, -!

unbranched tentilla. | Tentilla simple, unbran-

ched,

Tentacles always with a
series of tentilla, all or
some of which are bran-
ched.

' Tentilla all trifid, with three
terminal branches,

Tentilla polymorphous,
partly simple, partly
branched or palmate,

66. Aurophysa.

67. Oannophysa.

68. Linophysa.

69. Nedophysa.

70. Pneumophysa.

71. Rhizophysa.

Genus 66. Aurophysa,1 Haeckel, 1888.
Aurophysa, Hkl., System der Siphonophoren, p. 44.

Definition. — Rhizophysidae with ordinate cormidia and free internodes of the stem,
the gonostyles being attached on the base of the siphons. Tentilla simple, unbranched.

The genus Aurophysa comprises those Rhizophysidae which may be regarded as the
oldest and simplest forms of that family. The long tubular stem is divided into
numerous equidistant nodes ; attached to each node is an ordinate cormidium, composed
of a siphon with its tentacle and a monostylic gonodendron. The long internodes
between the cormidia are naked, as in Apolemia and the polygastric Calyconectae.
Aurophysa agrees in this important character with the following Cannophysa
(PI. XXIV.) ; both genera together represent the subfamily Cannophysidae. Aurophysa
differs, however, from Cannophysa in the form of the tentilla, which in the former are
simple cylindrical filaments (as in Nectophysa, PI. XXIII.), in the latter trifid, with
three terminal branches. I observed an interesting species of this genus, Aurophysa
ordinata, in December 1881, in the Indian Ocean, on the coast of Ceylon (off Colombo);

1 Aurophysa = Air-bladder, oivpa, (fvatt.

324 THE VOYAGE OF H.M.S. CHALLENGER.

the apical stigma of the pyriform pneumatophore was surrounded by a brown pigment-
star with eight rays ; the siphons were orange coloured, and the clustered gonophores,
attached near to their base, yellowish, the long tentacles similar to those of Nectop>liysa
(PL XXIII. figs. 5, 6). Very similar is Rhizophysa inermis, Studer (40, p. 13, Taf. i.
figs. 3, 8, 9, 10), taken in the eastern part of the Indian Ocean, south of Sumatra
(lat. 11° 18' S., long. 120° 8'E.). Studer tells us that this deep-sea form has no tentacles,
but he describes and figures tentacles with a series of simple tentilla (fig. 10), apparently
attached one to the base of each gonophore. I have no doubt that this was the usual
tentacle, arising from the base of the siphon, strongly contracted and twisted around the
base of the neighbouring gonophore.

Genus 67. Cannophysa,1 Haeckel, 1888.

Cannophysa, Hkl., System der Siphonoplioren, p. 44.

Definition. — Rhizophysidse with ordinate cormidia and free internodes of the stem,
the gonostyles being attached at the base of the siphons. Tentilla trifid, with three
terminal branches.

The genus Cannophysa has the same ordinate cormidia as the preceding closely
allied Aurophysa. It differs in the structure of the tentacles and the form of the
tentilla, which are not simple lateral branches of the former, but each provided with three
terminal appendages at the distal end. Cannophysa, therefore, bears the same relation
to Aurophysa as in the following subfamily (Linophysidie) Pmumophysa has to
Nectophysa. A beautiful species of this genus was observed by me in January 1867
in the Canary Island Lanzerote; it is described in the following pages (PL XXIV.)
as Cannophysa murrayana, and dedicated to my honoured friend Dr. John Murray.
A similar species, differing in the special form of the pneumatophore and the tentilla, was
found in the Tortugas, near Florida, and described in 1882 by Fewkes as Rhizophysa
gracilis (44, p. 269, pi. vi. figs. 1-6).

Cannophysa murrayana, n. sp. (PL XXIV.).

Habitat. — North Atlantic, Canary Islands, Lanzerote, January 7, 1867 (Haeckel).

Corm. — Two living specimens, both very movable and integral, were captured by
me in a current off Puerto Arrecife ; the smaller was a young specimen without gono-
phores, and is figured in the expanded state, swimming with snake-like motion, in fig. 3
(twice natural size) ; the larger was a fully developed specimen with ripe gonophores, and
is figured in the contracted state with spirally coiled up stem in fig. 1 (in profile), and
fig. 2 (from above), slightly enlarged. The fully expanded corm attained a length of

1 Ca?inoj>/ii/sa = Tube-bladiler, xivna, <fvaa..

REPORT ON THE SIPHONOPHORiE. 325

300 to 400 mm. or more, but when contracted measured only 20 to 30 mm. The long and
slender stem is a cylindrical tube scarcely 1 mm. in diameter when contracted, 2 or 3 mm.
when expanded. It bears a series of ten to twelve fully developed cormidia in the
larger specimen, besides numerous buds of young ones on the top of the stem, below the
float. The ordinate cormidia are separated by naked internodes of equal length, the
colour of the stem and the gonodendra is bright yellow, of the siphons and tentacles rose.

Pneumatophore (figs. 1-3, p, fig. 4, in profile ; fig. 5 from above). — The large ovate
or pyriform float has when contracted a length of 6 mm. and a breadth of 3 mm.; in the
expanded state more than double this. Its thick-walled pneumatocodon (or outer wall)
is separated by a wide cavity from the pneumatosac (or inner wall) ; this cavity (the
pericystic chamber) is closed above and opens below into the axial canal of the trunk;
its greater part is filled up by clustered groups of finger-shaped villi, which arise from
the hypocystic funnel (fig. 4, pv). The large exodermal giant-cells which compose
these villi reach the enormous size of 1*5 to 2 mm.; the surface of the villi is covered
with a simple layer of ciliated entoderm cells (fig. 6). The thin chitinous wall of the
cuticular pueumatocyst is covered outside by the simple exoderm-layer of the pericystic
pneumatosac, inside by the thick yellowish-green endocystic tapetum (fig. 4, pf) ; this is
composed of several strata of polyhedral exoderm-cells, filled with greenish granules
(fig. 7). The endocystic tapetum is wanting only in the uppermost third or fourth of
the pneumatocyst, which is covered outside by a hemispherical or cap-shaped mitra ocellaris
(figs. 4, 5, p>p)- Above this mitra, which is composed of red polygonal pigment-cells, are
visible the radial muscles (pm) and the circular muscles of the sphincter (jot), which
closes the stigma, or the apical opening of the pneumatocyst (fig. 5, p>0)- (F°r the
special structure of the pneumatophore, compare above, p. 308.)

Siphons (figs. 1-4, s). — The feeding polypites are large cylindrical tubes of rose-colour,
which open outside by the distal mouth, inside by the small proximal pedicle into the
trunk. The thick muscular wall is very extensible and contractile, as is also the mouth,
which may be expanded in the form of a circular suctorial disc. Distinct segments are not
visible on the siphon ; the greater part of its inside is covered with small and very
numerous hepatic villi.

Tentacles (fig. 8). — The large cylindrical and rose-coloured tentacle, which is attached
to the base of each siphon on its dorsal side, bears a series of very numerous tentilla ;
their size increases gradually towards the distal third of the tentacle ; this third is a
simple, thick, cylindrical tube, spirally coiled up, more deeply coloured, and covered with
small papillae, but without tentilla. The lateral branches are small and simple in the
proximal part of the tentacle, trifid in the middle part. Each fully developed tentillum
bears at the distal end an odd thick median club (fig. 9, to) with a short terminal filament
(if) ; and on both sides of it a pair of slender cylindrical lateral horns (tc). Each of
these three terminal appendages contains two rose-coloured cnidonodes, composed of

320 THE VOYAGE OF H.M.S. CHALLENGER.

spherical cnidocysts, a proximal and a distal. The cnidocysts, which are contained in the
middle ampullaceous dilatation of the odd median club (ta), are twice as large as those in
the five other cnidonodes. The three terminal branches of the tentillum are solid, rather
rigid cylinders, composed of a single column of large hyaline entoderm-cells, with a thin
exodermal envelope similar to those of many hydropolyps and of the Narcomedusse.
The canal of the tentillum ends at the base, from which the three branches arise ; its
surface is covered with papillas (fig. 9, ts).

Gonodendra (figs. 1 , 2,g). — The single large gonodendron, which is attached to each node
of the stem, immediately beyond the insertion of each siphon, has a bright golden-yellow
colour. It is like a group of clusters and is composed of numerous smaller gonodendra
(of the second and third order), the gonostyle being richly ramified. Each smallest group
(or secondary gonodendron) is composed, as usual, of a single medusiform gynophore
and a corona of club-shaped androphores, with a distal (rose-coloured) palpon. (Compare
PI. XXIII. fig. 8, and pp. 313, 328.)

Genus 68. Linophysa,1 Haeckel, 1888.
Linophysa, HkL, System der Siphonoplioren, p. 45.

Definition. — Rhizophysidse with loose cormidia, the gonostyles being attached to
the internodes of the stem, between the siphons. Tentacles simple, without tentilla or
lateral branches.

The genus Linophysa is represented by a single species only, inhabiting the depths of
the Atlantic between 800 and 1600 fathoms, and captured several times by Studer, who
described it under the name Rhizophysa conifera (40, p. 4, Taf. i. figs. 1, 2, 4, 7, 13-18).
It differs from all other Rhizophysidse in the simple form of the long tubular tentacles,
which bear no tentilla or lateral branches. The siphons possess sixteen black liver-ridges
(while the other Rhizophysidse possess hepatic villi). The strobiliform gonostyles seem to
alternate with the siphons, the cormidia being loose. Each gonostyle bears, like
a fir-cone, a spiral row of imbricated gonodendra, each covered by a scale (gonopalpon ?).
These and other structures described by Studer are so peculiar that Linophysa conifera
may be perhaps the type of a separate family — Linophysidse.

Genus 69. Nectophysa,2 Haeckel, 1888.

Nectophysa, Hkl., System der Siphonophoren, p. 45.

Definition. — Rhizophysidse with loose cormidia, the gonostyles being attached to
the internodes of the stem, between the siphons. Tentacles branched ; tentilla simple,
not branched.

1 Linophysa = Filament-bladder, fc<W, <pw«. 2 Nectophysa = Swimming-bladder, ufam;, (piacc.

REPORT ON THE SIPHONOPHOR^E. 327

The genus Nectophysa resembles Av.rophysa in the structure of the tentacles, and
has the same simple tentilla in the form of slender cylindrical filaments. Tt differs, however,
in the composition of the cormidia, which are not ordinate, but loose ; the gonostyles
are not attached to the base of the siphons, but alternate with them and are scattered
along the stem. A beautiful species of this genus was observed by me, in December
1866, in the Canary Island Lanzerote, and is described in the following lines (PI. XXIII.)
as Nectophysa wyvillei, dedicated to the memory of Sir Wyville Thomson. Another
closely allied species seems to be Rhizophysa eysenhardtii, described by Gegenbaur (10.
p. 78, Taf. xxxi. figs. 46-49).

Nectophysa wyvillei, n. sp. (PL XXIII.).

Habitat. — North Atlantic; Canary Islands, Lanzerote, December 26, 1866 (Haeckel).

Corm. — The long cylindrical stem has a rose-coloured exoderm, a yellowish entoderm,
and in the fully expanded state (figs. 1, 2) a length of 300 mm. or more and a thickness
of about half a millimetre ; in the contracted state, and spirally coiled upon itself (with a
dexiotropic spiral, fig. 3). it is much thicker (2 or 3 mm.) ; but its length is only 10 to
20 mm. The circular as well as the longitudinal muscles are strongly developed. The
specimen figured iu fig. 2 bore about a dozen fully developed siphons, besides some
younger ones on the apex ; and regularly alternating with them, midway between
each two siphons, a large gonodendron. The general colour of both is rose.

Pneumatophore (figs. 1-4, p). — The float exhibits the same structure as is described
above of Cannophysa murrayana (compare pp. 308 and 325, and PI. XXIV. figs. 1-7).
In the fully expanded state it was pyriform or ellipsoidal, in the contracted state
subspherical. As the corm was irritated, and the stem much contracted (fig. 3), the
pneumatocyst was constricted in its equator, and a large air-bubble (fig. 3, x) escaped from
the opened apical stigma (po) ; the animal sank down to the bottom of the glass vessel,
and some time afterwards was again expanded, the siphons being partly attached by a suc-
torial mouth -disc to the bottom (fig. 2). The apical half of the pneumatosac is covered by
a violet mitra ocellaris (fig. 3, pp), whilst the distal half of the large pericystic cavity
was filled with numerous hypocystic villi (pv) arising from the air-funnel. In the highest
state of contraction of the stem, after the total expulsion of air from the pneumatocyst,
the clustered villi were all pressed downwards into the dilated apical portion of the stem
(fig. 4,pv). (Compare p. 310.)

Siphons (figs. 1-4, s, 5). — The feeding polypites are in the contracted state short
rose-coloured spindles, in the expanded state cylindrical tubes 15 to 20 mm. in
length, 1 to 2 mm. in breadth. Their thick muscular wall is very expansible and
contractile, the inside covered with numerous small hepatic villi. No different segments

328 THE VOYAGE OF H.M.S. CHALLENGER.

can be distinguished. The distal mouth is often expanded in the form of a large circular
suctorial disc.

Tentacles (figs. 1, 2, 5, t). — The long and very expansible tentacle which arises from
the base of each siphon (on its upper or dorsal side) is a cylindrical tube of rose-colour.
purple at the distal end, beset with a series of very numerous simple lateral branches ;
their length increases gradually from the proximal to the distal end. These tentilla are
thin cylindrical filaments with a simple rounded distal apex. Their canal is excentric,
since the thickened dorsal wall is filled with spherical cnidocysts (figs, 6, kc, 7), whilst from
the thinner ventral wall arise numerous conical papillae, each of which bears a palpocil or
a feeling bristle (fig. G, tw).

Gonodendra. — The single gonodendron, which hangs down like a pediculate cluster
of grapes from each intern ode, midway between each two siphons, is rose-coloured and
composed of numerous secondary and tertiary gonodendra. Each of the latter (fig. 8) is
composed of a single large medusiform gynophore (f) and a corona of five to ten (usually
seven or eight) ovate androphores (h) around its base ; the distal end is occupied by a
large, very movable, spindle-shaped palpon (gq). Each branch of the gonostyle bears
two or three pairs of opposite secondary branches.

Genus 70. Pneumophysa,1 Haeckel, 1888.
Pneumoph ysa, Hkl., System der Siphonophoren, p. 45.

Definition. — Rkizophysidae with loose cormidia, the gonostyles being attached
to the internodes of the stem, between the siphons. Tentacles branched; tentilla trifid,
with three terminal branches.

The genus Pneumophysa differs from the preceding Nectophysa in the form of the
tentilla, which are not simple tubular filaments, but provided with three terminal
appendages similar to those of Cannophysa (PI. XXIV. figs. 8, 9). The odd median
appendage is larger and ampullaceous, whilst the two paired lateral horns are smaller and
slender. The cormidia are not ordinate, as in Cannophysa, but loose, so that a single
gonodendron is attached to each internode of the stem midway between two siphons
(almost as in Nectophysa, PI. XXIII. figs. 1-3). The single known species of this
genus, Pneumophysa gegenhauri, was observed by me in December 1881 in the Indian
Ocean, and will be described on another occasion. A second species, similar to this,
was noticed in my System der Siphonophoren (95. p. 45) as Pneumophysa mertensii
( = Epibulia mertensii, Brandt, 25, p. 33). But a closer examination of the excellent
figures which its discoverer, Mertens, has left of this species, taken in the Tropical
Pacific, has convinced me that it belongs to the following genus, Rhizophysa.

1 Pueumojphijsa = Air-bladder, Tniiipa., (pvect.

REPORT ON THE SIPHONOPHOR^E. 329

Genus 71. Rhizojrfiysa,1 Peron et Lesueur, 1807.
Rhizophysa, Peron et Lesueur, 14, Voyage aux terres australes.

Definition. — Rhizophysidae with loose cormidia, the gonostyles being attached to the
internodes of the stem, between the siphons. Tentacles branched; tentilla polymor-
phous, partly simple, partly branched.

The genus Rhizophysa is the oldest known form of Rhizophysidae, its Mediterranean
type having been described as early as 1775, by Forskal, under the name Physophorafili-
formis (11, p. 120, Tab. xxxiii. fig. F). Peron afterwards, in 1807, figured a similar form,
observed in the Atlantic, under the name Rhizophysa planostoma (14, pi. xxix. fig. 3).
Although this latter figure is very incomplete, it may be that it is identical with a
similar Rhizophysa, a single specimen of which I captured in December 1866, in the
Canary Island Lanzerote. The structure of this Atlantic species, for which I retain
Peron's name, was very similar to that of the well-known Mediterranean form, the best
description of which was published in 1854 by Gegenbaur (7, p. 324, Taf. xviii. figs.
5-11). The Atlantic Rhizophysa p>lanostoma differed, however, in the peculiar coloration
(the pneurnatophore, the stem, and the tentacles being rose-coloured, the siphons violet),
and in the special form of the tentilla; the majority of these were trifid, with an odd
median club and two paired lateral horns (similar to those of Cannophysa murrayana),
but scattered between them was a number of very large palmate tentilla, differing
from those figured by Gegenbaur (loc. cit., fig. 8) mainly by a large purple ocellus on the
convex outside ; the peculiar calcarate tentilla, which Gegenbaur compared with a bird's
head in the Mediterranean Rhizophysa filiformis (loc. cit., fig. 9), were absent. Compare
also Fewkes (41, pi. ii.). A third species of the true Rhizophysa, different from the two
former, is described by Brandt as Epibulia mertmsvi (25, p. 33). The excellent figure of it,
drawn from nature by Mertens (but unfortunately not published), exhibits distinctly two
different kinds of branched tentilla; the colour of the corm is yellowish-brown, the
siphons rose. It was observed in the Northern Pacific in 1827.

Family XXII. S a l a c i d m, Haeckel, 1888.

Salacklw, Hkl., System der Siphonophoren, p. 45.

Definition. — Cystonectae polygastricae with a long tubular trunk of the siphosome,
bearing in its ventral median line numerous polygastric cormidia, separated by free
internodes. Each clustered cormidium composed of several siphons and several
tentacles. Pneumatosaccus large, without radial septa and pericystic radial pouches,
but with eight or more radial groups of hypocystic villi.

1 .R/i»zop%sa = Root-bladder, pl^u, tpiasc.
(zoou CHALL. EXP. PABT LXXVII. — 1888.) Hhhh 42

330 THE VOYAGE OF H.M.S. CHALLENGER.

The family Salacidae is an interesting group intermediate between two very
dissimilar families of Cystonectse, the macrostelious Rkizophysidse (XXI.) and the brachy-
stelious Pkysalidse (XXIV.). It agrees with the former in the long tubular stem and the
long naked internodes between the ordinate cormidia, and further in the peculiar
structure of the pneumatophore, possessing hypocystic villi ; on the other hand, it agrees
with the Physalidae (PI. XXVI.) in the polygastric structure of the cormidia and the
large size of the float, and with Physalia especially in the structure of the siphons and
the simple tentacles, bearing a series of reniform cnidonodes.

The remarkable species which represents this connecting family is figured in PI.
XXV. as Salacia polygastrica ; it was taken by the Challenger in the Tropical Atlantic
(Station 338), from a dej^th of 1990 fathoms. The single specimen examined was so well
preserved that it was possible by staining and dissecting it to recognise the essential
structure of all the different organs. The morphological relation which the polygastric
cormidia of Salacidse bear to the closely allied monogastric cormidia of Rhizophysidse
is very similar to that which, among the Physonectse, the Apolemidse bear to the
Agalrnidse. An Apolemia which has lost its nectophores and bracts would be very
similar to a Salacia. The peculiar structure of the gonodendra, however, in this latter,
and the structure of the large float, with eight radial bunches of hypocystic villi, leaves
no doubt that they are most closely allied to the Rhizophysidse.

Genus 72. Salacia,1 Haeckel, 1888.
Salacia, HkL, System der Siphonophoren, p. 45.

Definition. — Salacidse with ordinate cormidia, each of which is composed of several
siphons and monostylic gonodendra. The single tentacle, which arises from the base of
each siphon, is a long simple tube, beset with a series of reniform cnidocysts.

The genus Salacia was established by Linnd in 1746 for that very large Cystonect
which was called Physalia by Lamarck in 1816 (compare 1, p. 158 ; 79, p. 24).
Since the latter name is generally accepted, and the former (although seventy years
older) entirely forgotten, I employ it for this new genus, instead of giving a new
name. The characters of the genus Salacia, as the only known type of Salacidae, are the
same as described above for that family. As a peculiar character of the genus may be
pointed out the shape of the tentacles, which agree with those of Physalia. The species
described in the sequel (PI. XXV.) was discovered by the Challenger in the depths of
the Tropical Atlantic (Station 338). Another species of the same genus seems to be
the (incompletely known) North Atlantic form, which Fewkes described in 1886 as
Rhizophysa uvaria (45, part xii. p. 967, pi. x. fig. 6).

1 Salacia, name of a sea-goddess, wife of Okeanos.

REPORT ON THE SIPHONOPHOR^. 331

Salacia polygastrica, n. sp. (PI. XXV.).

Habitat— Tropical Atlantic; Station 338, March 21, 1876; lat. 21° 15' S., long.
14° 2' W.; depth, 1990 fathoms.

Corm. — The trunk of the single specimen observed had in the expanded state a
length of 120 to 150 mm., and bore about eight developed cormidia, besides the same
number of young and undeveloped ones in the proximal portion, beyond the apical float.
The ordinate cormidia were separated by long naked internodes. The cylindrical trunk
was filiform and had a diameter of only half a millimetre, but exhibited a high degree of
firmness and elasticity. Although it was much contracted in the spirit bottle, it was
possible, by softening it gradually with water, to make it so elastic that it could be
extended to that degree which is figured in PL XXV. fig. 1.

Pneumatophore (fig. 1 , lateral view ; fig. 2, horizontal section, near the pylorus
infundibuli ; fig. 3, apical view, fore-shortened). — The large float is ellipsoidal, 10 mm.
long, 6 mm. broad. Its apex is truncate, with a central dimple, which contains the
stigma or the apical opening for the emission of gas (fig. 3,po). In the apical view
(fig. 3) strong radial muscles (pm) are visible, which open the stigma; beyond them lie
the circular muscles which compose the sphincter closing it. This eye-like sphincter is
surrounded by a corona of eight roundish radial lobes, covered by dark pigment-granules.
I could not make out the true nature of these lobes (fig 3, seen from above, and fig. 1,
in profile). The uppermost part of the pericystic cavity appeared to be divided by
eight radial septa into eight radial pouches opening below ; but the dark pigment
covering them (much richer than is represented in fig. 3) prevented their distinct
recognition. The apparent septa may be only radial folds.

Pneumatocyst. — The chitinous air-flask is spindle-shaped and occupies the upper
two-thirds of the float-cavity ; it exhibits two openings on the two poles of its axis, the
apical stigma for the emission of gas (fig. 3,po), and the basal pylorus infundibuli (fig. 2,
py), through which the gas, secreted by the exodermal epithelium of the infundibulum,
enters into the cavity of the air-flask. The outside of the cuticular pneumatocyst is
covered by its matrix, the exodermal pneumatosac ; this has an annular constriction round
the pylorus (fig. 2, py), and forms beyond it a hemispherical cavity, the infundibulum or
pneumatochone. From this arise eight radial bunches of hypocystic villi (figs. 1-3, pv),
which fill up the greater part of the hypocystic cavity. Each villus is composed of a
few colossal exodermal giant-cells (1 to 2 mm. in diameter) and of a ciliated epithelium
of small entoderm cells covering them (as in PI. XXIV. fig. 6).

Cormidia. — Each ordinate polygastric cormidium (fig. 4) is a botryoidal cluster
composed of about ten to twenty siphons and gonodendra, each siphon provided with a
long simple tentacle. Four to six siphons only seem to be fully developed in each

332 THE VOYAGE OF H.M.S. CHALLENGER.

cormidium and possess a distinct mouth- opening and a tentacle ; these are not
recognisable in a greater number of smaller and thinner spindle-shaped tubes, which arise
between the former; they may be either young and undeveloped siphons, or perhaps
palpons which remain permanently mouthless. The difference between siphons and
palpons in Salacia does not seem to be sharp, as in Physalia. All the components of each
cormidium arise from the node of the trunk so densely crowded that it is impossible
to determine whether there is any close relation between the clustered gonodendra and
the siphons.

Siphons (figs. 4, 5, s). — The fully developed polypites are slenderly spindle-shaped,
attain in the expanded state a length of 8 to 12 mm., a breadth of about 1 mm., and are
very similar to those of Physalia and Alophota (PI. XXVI. ). The four usual segments
are sometimes recognisable in the strongly contracted siphon (fig. 5). The short pedicle
bears a subspherical basigaster with thickened exoderm (sb) ; from its base arises the
tentacle (t). The wide stomach (sm) is covered inside with numerous pigmented
hepatic villi (sv). The contractile proboscis (sr) opens at the distal end by a mouth
which is often expanded in the form of a roundish or circular suctorial disc ; its margin is
armed with a ring of cnidocysts (fig. 4, so).

Tentacles (t). — The single long tentacle which arises from the base of each fully
developed siphon is very similar to those of Physalia, a simple cylindrical tube with an
excentric canal. The dorsal side of the tube bears a series of very numerous reniform
cnidonodes, whilst the ventral side is naked (compare PL XXV. figs. 4, 5, t, and
PL XXVI. figs. 1-6, t).

Gonodendra (figs. 4, g, 7). — The clustered gonodendra, which arise from each node
between the siphons, have a richly branched gonostyle. Each ultimate branch (PL XXV.
fig. 7) exhibits essentially the same structure as in Physalia, and is composed
(PL XXVI. fig. 8) of a single large gynophore (f, a medusiform umbrella with four radial
canals, the manubrium of which develops after the detachment), a clustered group of
smaller club-shaped androphores (h), and a number of gonopalpons (gq).

Family XXIII. Epibulid^e, Haeckel, 1

Definition. — Cystonectse polygastricse with a short inflated trunk of the vesicular
siphosome, which is spirally convoluted beyond the basal side of the large subvertical
pneumatophore. Cormidia ordinate in a spiral ring, protected by a corona of palpons.
Pneumatosaccus without radial septa and pericystic radial pouches, but with eight or
more radial groups of hypocystic villi.

The family Epibulidse represents a new interesting group of Cystonectse, which was
very imperfectly known up to this time. Two species only of Epibulia, both captured

REPORT ON THE SIPHONOPHORvE. 333

in the North Pacific, have been incompletely described — Epibulia chamissonis lay
Eysenhardt (77, Tab. xxxv. fig. 3), and Epibulia erythrophysa by Brandt (25, p. 34).
Unfortunately the excellent figure of the latter species, which Mertens in 1817 had drawn
from life, has never been published. It is much to be lamented that this, as well as
all the other wonderful drawings of Siphonophorse, which Mertens had executed with the
most admirable accuracy, have never found their way into literature. Comparing Mertens'
figure of Epibulia erythrophysa with a similar splendid Cystonect which I myself
observed in Ceylon (1882), I have no doubt that both species belong to one and the
same genus. The accurate examination of this Indian Epibulia ritteriana (PI. XXII.
figs. 6-8), and their comparison with the closely allied Physalidse, has led me to
the opinion that this genus represents a new family, intermediate between the latter and
the Rhizophysidse. Another genus of this family may be perhaps Angela cytherea of
Lesson, which, however, is too imperfectly examined (3, p. 496, pi. ix. fig. 1).

The Epibulidse agree with the next allied Physalidse in the bag-shaped form of the
short and wide trunk of the siphosome. But the large pneumatophore does not extend
along the dorsal side into the cavity of the vesicular trunk ; it occupies rather the apical
half of the corm, whilst the siphosome occupies its basal half. The Epibulidse agree in
this respect with the other Cystonectse, and differ essentially from the true Physalidse,
with which I had united them (in 1887) in my System (95, p. 46, Genus 73). A further
consequence of this important difference is that the main axis of the large pneumatophore
stands subvertically or obliquely inclined in the Epibulidse (as in the other Cystonectse),
whilst it is subhorizontal in the Physalidse ; the stigma, therefore (or the apical air-pore),
occupies in the former the superior pole, in the latter the anterior pole of the floating
corm. A further difference is, that the ventral line of the shortened trunk, from which
the budding cormidia arise, is circular or rather spiral in the Epibulidaa, straight in the
Physalidse, and that a complete corona of palpons surrounds the base of the float in the
former, but is wanting in the latter.

The whole form of the corm, as well as the structure of its single parts, is in the
Epibulidse very like that in the Cystalidse (PI. XXII. figs. 1-5) ; but the important
difference between them is that the former are polygastric, the latter monogastric. It
is very probable, however, that the Epibulidse have arisen directly from the Cystalidse
(by secondary multiplication of the siphons and tentacles), as well from a phylogenetical
as from an ontogenetical point of view (compare above, p. 315).

Nectosome (PI. XXII. fig. 6, p; fig. 7, longitudinal section ; fig. 8, transverse section). —
The pneumatophore has in the Epibulidse the same structure as in the Salacidse and
Rhizophysidse ; it includes eight radial bunches of hypocystic villi. Its apex bears the
stigma typical of all Cystonectse. The living Epibulia, when it wishes to sink down,
expels at will the gas through this apical pore ; as I have observed in Ceylon. -The
apical part of the pneumatosac is intensely coloured by a pigment-cap (mitra ocellaris, pp).

334 THE VOYAGE OF H.M.S. CHALLENGER.

Siphosome. — The composition of the siphosome, and especially the arrangement of the
crowded cormidia along the median ventral line of the vesicular and spirally convoluted
trunk, is in the Epibulidse very similar to that in the Discolabidse. If the nectophores
of Physophora or of Discolabe were detached and the stem contracted, and if the apical
float were inflated, the external appearance would be nearly the same as in Epibulia.
The corona of large projecting palpons which surrounds the base of the nectosome and
covers the siphosome is also very similar. It may even be that the composition of the
ordinate cormidia, and their arrangement around the segmented shortened trunk, is
very similar in both groups. But a closer examination informs us that this simil-
arity is a mere analogy, not a true homology; the typical structure of the single
persons and organs (mainly of the pneumatosac and the gonodendra) is in the
Epibulidse very different from that in the Discolabidse, and agrees with that in the
other Cystonectse.

Synopsis of the Genera of Epibulidse.

Tentilla simple, filiform, undivided, ........ 73a. Epibulia.

Tentilla trifid at the distal end, with an odd median terminal ampulla and two paired

lateral horns, .......... 736. Angela.

Genus 73a. Epibulia,1 Eschscholtz, 1829.
Epibulia, Eseh., System der Acalephen, p. 148.

Definition. — Epibulidse with simple filiform tentilla, each representing an undivided
lateral branch of the tentacle.

The genus Epibulia was founded by Eschscholtz (1, p. 148) for the reception of two
very different Cystonectse, viz., (l) the Mediterranean Rhizophysa jiliformis, Lamarck
(described by Forskal in 1775 as Physophora), and (2) Rhizophysa chamissonis,
Eysenhardt, from the North Pacific (77, p. 40, Tab. xxxv. fig. 3). Since the name
Rhizop>hysa is now generally accepted for the former, we retain the name Epibulia for
the latter. Another species, closely allied to this, was afterwards described by Brandt
as Epibulia erythropjhysa (25, p. 34). The excellent figure of this Pacific species,
which Mertens had painted from fife, but which, alas, was never published, leaves no
doubt that it belongs to this genus, and that it is closely allied to the new Indian species
which I myself observed living in Ceylon, and which is described in the sequel as
Epibulia ritteriana, dedicated to the highly esteemed protector of phylogenetic science,
Dr. Paul von Bitter of Basel (PL XXII. figs. 6-8).

Considerable confusion in the nomenclature of this genus (as also of other genera

1 Epibulia = Artful, im/SouKix.

REPORT ON THE SIPHONOPHORjE. 335

of Siphonophorse) was introduced by Carl Vogt (6), who in 1854 gave the name
Epibulia aurantiaca to a Calyconect, which had been named Galeolana by Blain-
ville seventeen years before (24, p. 139). Compare our Genus 26. Since also many
succeeding authors had retained the name Epibulia in the sense of Vogt, I followed
their example in my System, and had called the above mentioned species of Brandt, &c,
Arethusa (95, p. 35). But considering now more accurately the rules of priority, I
find it much more justifiable to employ the name Epibulia in the sense of the older
authors, Eschscholtz and Brandt.

Epibulia ritteriana, n. sp. (PI. XXII. figs. 6-8).

Arethusa brachysoma, Hkl., System der Siphcmophoren, p. 46.
Habitat. — Indian Ocean, Ceylon, off Belligemma, January 1882 (Haeckel).

Corm. — The comj^lete corm of this beautiful Cystonect, which I captured in the living
state, off Belligemma, Ceylon, and which is figured in PL XXII. fig. 6, four times enlarged,
had in this fully expanded state a diameter of 30 mm. to 40 mm., in the contracted state
scarcely one-fourth of that size. All parts of the body were splendidly coloured, the large
ovate pneumatophore light red, with a purple pigment-cap in the apical third ; the
corona of palpons rose, the siphons and the tentacles yellow, and the gonodendra purple.
The vivid motions of this delicate Siphonophore, the variable play of the tasting palpons,
the feeding siphons, and the capturing filaments, offered a most splendid aspect. The
number of cormidia composing the corm was eight ; four siphons and tentacles, and four
large gonodendra were fully developed, two others (smaller) half developed, and two very
small and young. The number of palpons, however, which composed the corona beyond
the apical pneumatophore, was very large, forty to sixty or more, beside many young
buds, so that six to ten palpons may belong to each cormidium. All these parts of the
siphosome were so arranged around its vesicular axial trunk, that the palpons occupied
the proximal, the siphons the distal part of the cormidium, and the gonodendra were
attached between them (as in the A nthophysidse and Discolabidae) ; but usually the
siphons were more or less protruded, so that the gonodendra appeared to occupy the
central base of the corm. Unfortunately, I was not able to examine closely the form of
the central trunk of the siphosome, and the mode of attachment to the cormidia ;
probably it is similar to that of the Anthophysidae, Discolabidse, and Nectalidge ; all that
I could observe of the trunk was that it represented a shortly conical or ovate bladder,
coiled up in a spiral, with a single dexiotropic turning.

Pneumatophore (PL XXII. fig. 6, p, in profile ; fig. 7, in vertical section through the
axis ; fig. 8, transverse section). — The great float filled with air is ovate, and has a
diameter of 10 to 12 mm. in the expanded state; in the contracted state, however,

336 THE VOYAGE OF H.M.S. CHALLENGER.

after the emission of gas through the apical pore, it represented a depressed spheroid
of 3 to 4 mm. only. The pneuniatocodon, or the outer wall of the pneumatophore
(fig. 7, pu), is separated from the inner wall, or the pneumatosaccus (fig. 7, ps), by a wide
cavity (pc). This pericystic cavity opens below into the stem-cavity of the siphosome
(at), whdst it is closed above, surrounding like a ring the apical pore (po) where both
walls are connected. The distal or inferior half of the pericystic cavity is filled by the
numerous finger-shaped hypocystic villi (pv), arising in eight radial bunches from the air-
funnel (pi).

Pneumatocyst (figs. 6-8, pf). — The chitinous air-flask is an ovate bladder, suspended
from the apex of the surrounding pneumatophore, and hanging down freely into its
cavity. Its cuticular wall has two opposite openings on the poles of its axis. The
superior or proximal opening is the apical stigma (po) serving for the emission of gas when
the animal wishes to sink down ; it may be closed by the sphincter stigmatis, a strong
ring-muscle, the antagonist of which is a corona of radial muscles, opening the stigma.
The inferior or distal opening of the air-flask is the pylorus infundibuli (p)y), by which
its cavity communicates with the subjacent air-funnel (pi). The convex outside of the
pneumatocyst is covered by the simple exodermal epithelium of the pneumatosac (ps),
and in the upper third by the mitra ocellaris, a purple hemispherical cap composed of
elegant polygonal pigment-cells (pp). The concave inside of the air-flask is naked in the
upper third (covered by the ocellar mitra, pp) ; it is lined in the two lower thirds by
the endocystic tapetum (pd), a stratified glandular epithelium composed of the same
yellowish-green exoderm cells as line the cavity of the subjacent spheroidal air-funnel
(infundibulum, pi). The greenish glandular epithelium is the important pneumadenia
and secretes the gas.

Hypocystic Villi. — The air-funnel (infundibulum or pneumatochone, pi), which
forms the blind distal portion of the air-sac, is surrounded by a regular corona of eight
radial clusters, composed of numerous branched hypocystic villi. Each villus is com-
posed of a few colossal giant-cells of the exoderm (arising from the outside of the
pneumadenia) and covered by a vibratile epithelium of small ciliated entoderm-cells
(PI. XXIV. fig. 6). The diameter of the vesicular giant-cells is 1 to 2 mm., and their
nuclei, when stained by carmine, are visible to the naked eye. The further structure
and the physiological function of these parts are the same as in the Khizophysidaa,
(described above, pp. 310, 320).

Sip>hons (fig. 6, s). — The large feeding polypites are 10 to 15 mm. long, very
movable spindle-shaped tubes with a thick muscular wall. The short basal pedicle
bears the tentacle on its dorsal side. The largest part is the dilated stomach, covered
inside with numerous yellow hepatic villi. The distal proboscis is very muscular ; its
mouth-opening may be expanded in the form of a circular suctorial disc, the margin of
which is divided into sixteen lobes.

REPORT ON THE SIPHONOPHOR7E. 337

Tentacles. — The single tentacle which arises from the base of each siphon is a long
cylindrical tube, in the fully expanded state 80 to 120 mm. long or more. It is beset
with a series of very numerous tentilla or lateral branches. These are simple, cylindrical
filaments, of the same shape as in Nectophysa wyvillei (PL XXIII. figs. 5, 6). The
concave ventral side of the tentilla bears sensible papillae, the convex dorsal side is
armed with spherical cnidocysts.

Palpons. — The corona of tasters, which occupies the uppermost part of the sipho-
some, immediately beyond the float of the nectosome, is very similar to that of the
Discolabidse (Physophora). The palpons (q) are slender, very movable, cylindrical tubes
with a thick muscular wall. Their cavity opens at the proximal end into the vesicular
trunk, whilst the closed distal end is armed with cnidocysts and a purple ocellus. Their
function is not only sensory, but also protective and capturing, as in the Discolabidse.

Gonodendra. — Each cormidium is monoclinic and bears a very large gonodendron,
attached by a short pedicle to the periphery of the vesicular trunk, between the superior
palpons and the inferior siphon. The gonostyle is richly branched, and each ultimate
branch, similar to that of the Salacidse (PI. XXV. figs. 6, 7), bears a large, distal,
medusiform gynophore and a bunch of club-shaped androphores with small gonopalpons
scattered between them.

Epibulia ritteriana, observed in the living state, with its vivacious movements,
belongs to the most beautiful and elegant forms of Siphonophorae ; at the same
time it is of a peculiar morphological and phylogenetic interest. I dedicate, therefore,
this splendid Indian form to my honoured friend, Dr. Paul von Ritter of Basel, the
magnanimous founder of the " Paul von Ritter'sche Stiftung fur phylogenetische
Zoologie an der Universitat Jena."

Genus 736. Angela,1 Lesson, 1843.

Angela, Lesson, Acal&phes, p. 496.

Definition. — Epibulidae with trifid tentilla, each lateral branch of the tentacles being
divided at the distal end into a terminal ampulla and two lateral horns.

The genus Angela was established by Lesson (loc. cit., p. 496, pi. ix. fig. 1) for
a Siphonophore, a figure of which, drawn from life, had been given to him by
Rang, without description. Comparing this figure with our Epibulia (PI. XXII. fig. 6),
I suppose that Angela cytherea (from the Tropical Atlantic?) may have been a true
Epibulid. The base of the large, depressed, spheroidal pneumatophore is surrounded by
a corona of numerous palpons, and inside of it depend eight very long tentacles,
provided with a series of numerous tentilla. Each tentillum is divided into three

1 Angela, a female angel.
(ZOOL. CHALL. EXP — PART LXXVII. — 1888.) Hhhh 43

338 THE VOYAGE OF H.M.S. CHALLENGER.

terminal branches, an odd median ampulla and a pair of lateral horns (fig. 1, a). If
this explanation be right, Angela would bear the same relation to Epibulia as Canno-
physa does to Aurophysa.

Family XXIV. Physalid^e, Brandt, 1835.
Physalidm, Brandt, Prodromus descriptionis, &c, SJ5, p. 36.

Definition. — Cystonecta3 polygastricae with a short inflated trunk of the vesicular
siphosome, which is horizontally expanded along the ventral side of the subhorizontal
gigantic pneumatophore. Cormidia in a multiple series along the ventral side of the
trunk, usually loose. Pneumatosaccus very large, sometimes with a chambered dorsal
crest, without radial septa and hypocystic villi.

The family Physalidse comprises the largest and most interesting Cystonectse, which
surpass all the other Siphonophorae in the enormous size of the inflated pneumatophore
and the vigorous tentacles, the splendid colours of the peculiar siphosome, and the
dangerous poisons of the urticating organs. Since some forms of this interesting
family, and especially the largest of all, the Atlantic Caravella maxima, occur in great
swarms floating on the surface of the ocean, they have been well known to travellers and
sailors for a long time. In maDy voyages they are mentioned under the popular names
" Caravella, Galera, Fregatta, Ship of Guinea, Portuguese Man-of-War," &c. Never-
theless the natural history of the Physalidse has hitherto been very imperfectly studied,
and there remains much to be done towards a complete knowledge of them.

The genus Physalia, generally accepted as the only one of this family, was established

in 1816 by Lamarck (90) for those Caravellse which 0. F. Midler and Gmelin in the

preceding century had described as Medusa caravella, Linnd, or Holothuria physalis.

Neither the name Salacia, employed for them by Linne in a few editions of his

Systema naturae (1756, 1, p. 158), nor the name Arethusa, proposed by Patrick

Browne in 1789, have yet any application (compare above, p. 330, and below, p. 349).

While Lamarck distinguished five different species, with very insufficient definitions,

Eschscholtz accepted only three, the common Atlantic Physalia caravella (the largest of

all, with numerous large tentacles), the smaller Physalia pelagica (from the Southern

Atlantic and Indian Oceans), and the larger Physalia utriculus from the Pacific ; the two

latter species have only a single large tentacle, and differ mainly in the form of the

pneumatophore. Recently Chun, in the latest paper on Physalia (83, p. 557), unites

these two latter forms, accepting two species only of this genus — Physalia caravella, with

many large main-tentacles, from the Atlantic, and Physalia utriculus (including Physalia

pelagica) from the Indo-Pacific Ocean. All recent authors have accepted the genus

Physalia as the only type of this family.

REPORT ON THE SIPHONOPHORjE. 339

The family Physalidse was established in 1835 by Brandt (25, p. 36). He first
distinguished two different subgenera in the genus Physalia, viz., (l) Scdacia (or Phijsalia
proper), with a chambered dorsal crest of the float; and (2) Alophota, without crest. This
distinction, although not accepted by later authors, is very important, since the crestless
state of the pneumatophore, regarded from a phylogenetic point of view, must necessarily
precede the crested state. There still exist also to-day small Physalidae which reach
sexual maturity in the crestless state. We establish for these the subfamily Alophotidae,
and oppose it to the crest-bearing subfamily Caravellidse. Among the small Alophotidse,
as well as among the large Caravellidse, occur two different forms which may be distin-
guished as genera ; one of these (Alophota and Physalia) bears only a single large main
tentacle, besides numerous small accessory tentacles ; the other group (Arethusa and
Caravella) bears numerous large main tentacles of nearly equal size (besides the small
accessory tentacles).

The distinction of species in these four genera of Physalidae is a very difficult task,
since the entire family is transformistic, and all the so-called " good species " are
connected by Darwinian intermediate forms. Nevertheless there exist a number of
" geographical species " as local forms in the different seas. In the majority of the
numerous descriptions the species of Physalidse are founded upon slight differences in the
variable coloration, or different states of contraction of the very variable pneumatophore
and other parts (compare Huxley, 9, p. 99, and Chun, 83, p. 557). A better and more
natural distinction of " relatively good species " will be got when the future observers
carefully regard the following anatomical structures : — (1) the grouping and composition
of the monogastric or polygastric cormidia ; (2) the relation of the basal protosiphon (at
the distal end of the float) to the secondary siphons (or metasiphons) on its ventral face ;
(3) the difference in structure and form of the pneumatophore, mainly at its apical and
basal poles ; (4) the structure of the crest, the number of its chambers, &c.

Cystonula-Larvse. — The organisation of the large adult Physalidse, with their com-
plicated structure and composition of hundreds of polymorphous parts, is so difficult to
conceive, and seems to be so widely different from that of other Siphonophorse, that it
has led most authors to many erroneous opinions. To arrive at its true understanding, it
is indispensable to regard carefully and compare critically the smallest and simplest forms
of this peculiar family, and especially the youngest larvae with a very simple structure
(Cystonula, PL XXVI. figs. 1, 2). The first larvae of a very young stage were described
in 1859 by Huxley (9, p. 102, pi. x. figs. 1, 2). I myself had in 1866, in Lanzerote, the
opportunity of observing living a number of similar larvae and of comparing them with
the simplest and oldest genus of the family, Alophota (PI. XXVI. fig 3), and with
the more highly developed Arethusa (figs. 4-8). Recently Chun has published some
interesting notes on young Physalidse (83, p. 558).

The smallest and youngest Cystonula, which I observed in December 1866, is figured

340 THE VOYAGE OF H.M.S. CHALLENGER.

in PI. XXVI. fig. 1 ; it had a length of 4 mm. in the expanded, 2 mm. in the contracted
state, and was very similar to the youngest larvse figured by Huxley (9, pi. x. fig. l).
This young larva is a simple medusome, composed of an ovate pneumatophore (the
transformed umbrella) and a spindle-shaped siphon with a distal mouth (the manubrium
of the original Medusa) ; from the vesicular pedicle of the siphon, which connects it with
the base of the pneumatophore, arises a single long tentacle ; this is a simple cylindrical
filament, beset on the dorsal side with a series of reniform cnidonodes, of the same structure
as in the adult Physalidse. The ovate pneumatosaccus (fig. 1 , pf) exhibits an apical
stigma (])o), or a simple pore on the proximal pole of the longitudinal axis ; this is the
permanent opening of the original invagination. The cavity between the outer and inner
walls of the pneumatophore (closed above around the stigma) is below in open com-
munication with that of the pedicle, and by this with the cavities of the siphon as well
as the tentacle. The inside of the siphon is covered with numerous black hepatic villi
(sv) ; the margin of the mouth (expanded in fig. 1 as a scmare suctorial disc) armed with a
series of cnidocysts (ss).

A second stage of Cystonula, 6 mm. in length, which I found recently in a prepar-
ation in the Challenger collection, and could not figure in PI. XXVI. (already printed),
is intermediate between figs. 1 and 2 of that Plate. It differed from the youngest stage
(fig. 1) in the production of a pair of buds from the ventral side of the dilated siphon-
pedicle (a), opposed to the dorsal tentacle (t). The posterior bud of this pair develops
into the first secondary siphon, the anterior into the first palpon (or basal sac) with its
tentacle. The dilated cavity between float [pf) and stomach (sv), from which the buds
arise, becomes now much larger and corresponds to the common stem or trunk («).

The third stage of Cystonula observed is figured in PL XXVI. fig. 2 ; its length
in the expanded state was 8 mm. It is similar to the second form figured by Huxley,
10 mm. in length (9, pi. x. fig. 2). The slender pyriform trunk, with strongly inclined axis,
encloses in its proximal (anterior) half the pneumatosac, filled with air (pf), and bears on
its distal (posterior) end the protosiphon (the primary siphon or the manubrium of the
original medusome, with its tentacle). This is separated by a wide interval from the
central group, composed of three subequal cormidia which are attached to the middle
third of the ventral median line of the vesicular trunk ; each cormidium is composed of
two sterile persons arising from a common stem, a siphon (with hepatic villi, sv, and a
terminal mouth), and a mouthless palpon (or basal ampulla, with a long tentacle).
Regarded from the standpoint of our Medusome Theory, this Cystonula is a primary
medusome, which has produced by budding from its ventral side three pairs of
secondary medusomes ; these arise from the middle third of the trunk, or from that
portion which is the enlarged pedicle of the protosiphon (fig. 1, a). The growing
pneumatophore, which originally occupied the apical part of the primary larva, extends
now more and more over its dorsal side, descending in a basal direction. The longi-

REPORT ON THE SIPHONOPHOR^E. 341

tudinal axis, originally subvertical, becomes in this way inclined more and more, and
finally lies subhorizontally.

The further development of the Physalidse is determined mainly by the multiplication
of the cormidia on the ventral or inferior side of the vesicular trunk, and by the progres-
sive extension of the pneumatosaccus along its dorsal or superior side. In Alophota and
Phijsalia, where the single large main tentacle is much longer than all the others, usually
the two groups of cormidia (the larger ventral and the smaller basal) remain separated,
and their further development is different. The smaller basal group, at the posterior or
distal end of the trunk, produces merely a series of small siphons and palpons, placed
before the protosiphon, and is provided with a single tentacle only ; it always remains sterile
and never produces gonophores. The larger ventral group produces early a very large
main tentacle, with a gigantic main palpon, much longer and stronger than all the
others. The number of cormidia in this ventral group is much larger, and the siphons
as well as the palpons and the accessory tentacles become very numerous in the larger
species. Some of them afterwards produce gonodendra. In Arethusa and Caravella,
on the other hand, the number of main tentacles increases, and usually the two groups
of cormidia (smaller basal and larger ventral) are early united into a single large mass of
crowded appendages. The succession and composition of the cormidia seem to follow,
however, somewhat different laws in the various species of Physalidse.

The further development of the pneumatophore in the larvae of Physalidse has
recently been described by Chun (83, p. 559). The inferior or basal third of the
invaginated pneumatosaccus becomes separated from the superior larger portion by an
annular constriction. The cylinder-epithelium of the former is the pneumadenia, which
afterwards expands in the form of a gas-secreting "basal plate" ("Luftplatte"). Physalia
and Caravella afterwards develop the dorsal crest which is wanting in the float of Alophota
and Arethusa.

Truncus. — The marked peculiarity in which the Physalidse differ from all other
Siphonophorae, is the strange development of the hypertrophic pneumatophore along the
dorsal side of the common trunk. The nectosome, therefore, occupies in this family the
entire dorsal half of the corm, whereas the siphosome takes the ventral half; the main
axis of the trunk becomes subhorizontal, whilst it is vertical in the other Siphonophorae ;
the nectosome occupies in these latter the apical or proximal, the siphosome the basal or
distal, part of the corm. The naked dorsal face of the trunk, which bears no appendages
but includes the float, is in all Physalidse much larger than the ventral face which bears
the cormidia of the siphosome. The cavity of the trunk is wide, and when the gas is
expelled through the stigma of the contracted float, the trunk appears as a voluminous
sac filled with nutritive fluid. The trunk in the Physalidse is never coiled up spirally as
in the allied Epibulidse.

Pneumatophore. — The gigantic float of the Physalidse determines by its excessive

342 THE VOYAGE OF H.M.S. CHALLENGER.

unilateral development along the dorsal side of the trunk, the peculiar form and the
strange character of this family. Nevertheless the young larvae (Cystonula, PI.
XXVI. fig. 1) are not essentially different from those of other Cystonectse (e.g., Cystalia,
PI. XXII. figs. 1-5). The float is here a relatively small ovate or ellipsoidal vesicle in
the apical part of the primary medusome, connected by the inflated pedicle (a)
with the basal protosiphon (sa). The stigma on its apical pole (po) is the permanent
opening of invagination, from which the simple pneumatosac (or the inner float- wall)
depends freely into the pneumatocodon (or the outer float-wall). Chun tells us that the
float of these young larvae has a complete radial structure ("ein vollig radialer gebauter
ovaler Luftsack," 83, p. 559); but I have never found in the Physalidae (neither the
youngest larvae, nor older forms) any trace of radial structure; they possess neither the
eight radial bunches of hypocystic villi which are found in the Epibulida? (PI. XXII. figs.
6-8), the Salacidae (PI. XXV. figs. 2, 3), and the Rhizophysidae (PI. XXIV. figs. 1-5), nor
the corona of radial septa and pouches which is obvious in most Physonectae. The
pneumatosac of all Physalidae lies freely in the voluminous cavity of the large pneumato-
codon, and is connected with the latter only at the apical pole, by the sphincter of the
stigma. The pericystic cavity, therefore, is as simple as in the Cystalidae, Athoridae, and
Apolemidse. The outer wall of the float is very thick and muscular, with an outer layer
of strong, parallel, longitudinal fibres and an inner layer of circular ring-fibres. By
compressing the float voluntarily, the animal can extrude the included air through the
apical stigma, and sink down. After a short time has elapsed it can rise again, secreting
a great mass of gas by the pneumadenia, and filling the float. I often observed this process
repeated, in December 1866, off the Canary Islands. The lamellar pneumadenia, or
the glandular "air-plate" ("Luftplatte," Chun, 83, p. 569), which corresponds to the
endocystic tapetum of the other Cystonectae (p. 309), is a thin distal layer of exodermal
glandular cylinder-cells, placed originally in the basal portion of the pneumatosac. It
grows afterwards more towards the ventral side and extends forwards. It has a diameter
of 4 mm. in a float 20 mm. in diameter. But in the adult Caravella maxima it reaches
100 to 150 mm. in diameter, and occupies nearly the ventral half of the pneumatophore.
Asymmetry of the Corm. — The fundamental form of the bilateral corm is in all mature
Physalidae more or less asymmetrical, either the left or the right side being more
developed and organised differently from the opposite side. This asymmetry is less
expressed in the crestless Arcihxmidas (Alophota, Arethusa); it is much more prominent in
the crest-bearing Caravellidse (Physalia, Caravella). But the young monogastric larva
(Cystonula, PI. XXVI. fig. 1) is monaxonial, and only the tentacle arising from the
ventral median line marks the bilateral symmetry. As soon as the budding of the
secondary cormidia on the ventral side of the primary medusome commences, the
subvertical axis of the latter becomes more and more inclined, and finally subhorizontal.
The first trace of the asymmetrical development is then marked by the situation of the
v

REPORT ON THE SIPHONOPHORjE. 343

different buds, the siphons on one side, and the palpons and tentacles on the other side;
afterwards all the gonodendra lie on one side (right or left, figs. 3, 4). The more the trunk
becomes inflated by the hypertrophied float, the more it lies on one side of the body. On
the opposite side is developed the crest of the Caravellidse, acting the part of a sail, similar
to that of the Velellidae. As in these latter, the unilateral situation of the sail (right or
left) is accidental, and is not constant in the single species ; but usually in each species (as
with the eyes of the Pleuronectidse) the majority have the crest on the same side (compare
Chun, 83, p. 576). The largest siphons and palpons, and the main tentacles, lie on this side
(the lophopleura), while the gonodendra develop on the opposite side (the hypopleura).
Compare L. Agassiz, 36, p. 335. The different growth of the two antimeres (or body-halves)
is in some Physalise {e.g., Physalia utriculus, 77, Tab. xxxv. fig. 2) so striking, that the
median plane of the dorsal crest lies more horizontally than vertically, and the usual
ovate or pyriform shape of the float becomes triangular; the distance between the anterior
stigma (on the apical pole of the main axis) and the posterior protosiphon (on its basal
pole), seen from above, is in this case often scarcely half as great on the lee-side, or the
hypopleura (which bears the gonodendra), than on the windward-side or the lophopleura
(which bears the crest). It must be remembered, however, that the free edge of the
comb-like crest is always originally the dorsal median line of the asymmetrical trunk,
and the line in which the cormidia bud the ventral median line. The anterior stigma
marks constantly the apical pole of the longitudinal main axis, and the mouth of the
posterior protosiphon its basal pole.

Crest of the Float. — The remarkable polythalamous comb-like crest of the
pneumatophore, which is usually regarded as the most striking peculiarity of this family,
is developed only in the larger Caravellidse (Physalia and Caravella) ; it is wanting in
the smaller Arethusidae, which, because of their much smaller size and simpler
form, have usually been overlooked (Alophota and Arethusa, PL XXVL). It is
wanting, also, in the younger larvae of the Caravellidae. The crest, therefore,
is a secondary organ, got by adaptation to the. sailing locomotion of the hydro-
static float. Eegarded from a morphological point of view, it is nothing more
than a simple longitudinal fold in the dorsal median hue of the trunk. It
becomes divided afterwards by a number of transverse septa into a series of
triangular air-chambers. These have often been compared with the chambers
in the polythalamous pneumatocyst of the Disconectse. But this comparison is only a
remote analogy, not a true homology. The morphological affinity which is suggested by
most authors between Physalidae and Velellidae does not exist at all. On the structure of
the crest and its relation to the float, compare Leuckart (81, p. 192), L. Agassiz (36, p. 335,
pi. xxxv.), and Chun (83, p. 576). The number of the primary chambers in the crest of
young Caravellidae is three or four, in the older six to eight or more. These become
divided by smaller transverse septa into secondary chambers, and these again by smaller

344 THE VOYAGE OF H.M.S. CHALLENGER.

tertiary septa into chambers of the third (sometimes even of the fourth) order (compare
Olfers, 79, fig. 1 ; Leuckart, 81, fig. 2 ; L. Agassiz, 36, fig. 1, &c). Possibly the number of
these chambers corresponds to that of the cormidia, which arise in metameric succession
from the opposite ventral side of the trunk ; it is different in the various species. The
Physalidse are able to compress the float and the crest in a very variable manner, and to
change their form in a most extraordinary degree. The external form of these hydro-
static organs, therefore, is of little value for the distinction of species.

Cormidia. — The numerous groups of polymorphous persons and organs which
compose the corm of the Physalidse are usually loose, and represent, especially in the
larger species, a clustered mass of crowded parts, which seem to be aggregated without
any regular order. A comparative examination, however, of the younger stages and
larvae, and especially of the small mature Alophota (PI. XXVI. figs. 1-3), informs us that
at the very beginning the cormidia are here also more or less ordinate. A single series of a
few cormidia (four in Cystonula, fig. 2; six in Alopliota, fig. 3; eight to ten in Arethusa,
fig. 4) is here attached along the ventral median line of the trunk, and usually each of
these cormidia (excepting the basal group at the distal end) is composed of a siphon, a
palpon, and a tentacle ; and in mature corms also of a gonodendron. The internodes of
the trunk, or the free intervals between the succeeding cormidia, are very distinct in the
smaller and younger forms (figs. 2, 3), whilst they disappear in the larger and older
forms (figs. 4, 5). The cormidia of the former are originally monogastric (as in the
Rhizophysidaa), whilst they become polygastric in the latter (as in the Salacidse).

Basal Cormidium. — The distal end of the trunk, which is the posterior in the usual
position of the corm (with horizontal main axis), bears in all Physalidae a separate
cormidium of special interest (figs. 3, 4, su). We call it the " basal cormidium," since
it is placed at the base or the distal pole of the main axis, opposite to the apical stigma
on its proximal pole (po). This primary or basal cormidium remains always sterile, and has
a different morphological and physiological value from the numerous secondary cormidia
which arise from the ventral side of the trunk and afterwards produce gonodendra. In
the simplest case (fig. 3) the basal cormidium consists of a single siphon (su), a palpon
(g), and a tentacle. The siphon placed at the very distal end, in the prolongation of
the horizontal main axis, has the greatest morphological interest ; it is the primary
siphon of the youngest larva (fig. 1), and therefore the original manubrium of the
primary medusome, the umbrella of which is the float ; we call it the protosiphon or
primary siphon, in order to distinguish it from all the other siphons, secondarily
produced, or the metasiphons. The primary tentacle (fig. 1, t) which belongs to the
protosiphon, remains either as the single tentacle of the basal cormidium, or it is after-
wards lost ; but I have never seen secondary tentacles developed in this distal group ;
usually it is composed afterwards of a series of small secondary siphons or palpons (twelve
to twenty or more). The interval between the basal cormidium and the larger group of

REPORT ON THE SIPHONOPHOR^. 345

ventral cormidia is in most Physalidse permanent, sometimes larger, at other times
smaller, than in Alophota giltschiana, fig. 3, Physalia pelagica (77, Tab. xxxv. fig. 2), &c;
it is lost afterwards in those species, in which the number of cormidia is exceedingly
augmented, and all are confluent in a single crowded mass (as in Arethusa challengeri,
figs. 4, 5, in Caravella maxima, and in Physalia megalista).

Ventral Cormidia. — The numerous secondary cormidia which compose the large
main group of appendages, on the ventral side of the trunk, exhibit a great variety in
number, size, composition, and arrangement. Possibly these differences are constant in
different localities and possess therefore a systematic value ; but they recpiire a far more
accurate anatomical examination than has been employed hitherto. Originally each
secondary cormidium (in most species at least) seems to be monogastric, composed of a
single siphon, a palpon, and a tentacle, and in small mature conns of a gonodendron
(fig. 3) ; but usually the common pedicle of these medusomes afterwards branches, and
produces a variable number of tertiary cormidia. Generally a single tentacle and the
appertaining palpon, in the middle of the ventral group, becomes early much larger than
all the others ; this predominant main tentacle remains single in Alophota and Physalia,
whilst a variable number of similar gigantic main tentacles (usually ten to twenty) is
afterwards produced in Arethusa and Caravella. Many secondary cormidia remain sterile
in most Physalidse, and a small number only (usually eight to twelve) develop a large
gonodendron. It may be, perhaps, that in the crest-bearing Physalidse (Physalia and
Caravella) the number of large primary air-chambers in the crest (usually eight to twelve)
and their metameric succession often correspond to the segments of the trunk, from
which arise the primary groups of ventral cormidia.

Siphons. — The feeding polypites exhibit in all Physalidse the same shape, and are
very similar to, those of the Epibulidae (PI. XXII. fig. 6) and Salacidse (PI. XXV. fig. 5).
The protosiphon (or the primary polypite of the basal cormidium) does not differ in
structure from the numerous metasiphons (in the secondary cormidia of the large ventral
group). The young siphons are simple spindle-shaped tubes, whilst the fully developed
exhibit distinctly three or four different segments (PI. XXVI. fig. 6). The two proximal
segments, viz., the thin pedicle (sp) and the vesicular basigaster (sb), are usually small,
and often confluent ; the two distal segments, however, are always large and distinct.
The stomach is a very dilatable sac, inside covered with numerous black hepatic villi
(sv); the proboscis is a very muscular cylindrical tube, very contractile and expansible,
and opens by a mouth, which may be expanded in the form of a circular or polygonal
(often square) suctorial disc (fig. 1, ss) ; its margin is armed with a series of cnidocysts
(compare on the structure of the siphons, Leuckart, 81, Huxley, 9, &c).

Palpons. — All Physalidse possess, intermingled with the mouth-bearing siphons, a
larger number of mouthless palpons. These are of two kinds. The first kind exhibits
the same structure as the siphons and differs only in the absence of a distal mouth-opening.

(ZOOL. CHALL. EXP PART LXXVII. — 1888.) Hhhh 44

346 THE VOYAGE OF H.M.S. CHALLENGER.

They arise partly from the pedicles of the cormidia, partly from the branches of the
gonodendra ; it may be that many of the former (or perhaps all ?) are young siphons,
which afterwards get a mouth-opening. Those which arise constantly from the branches
of the gonodendra may be distinguished as gonopalpons (fig. 8, q). The second kind of
palpon is connected with the tentacles, so that always a single tentacle (fig. 6, t) arises
from a common pedicle with a single palpon (fig. 6, to). These tentacular palpons are
simple, very contractile, cylindrical tubes, closed at the pointed distal end, whilst their
proximal end opens into the common pedicle ; they do not possess the hepatic villi of
the first kind. Eschscholtz even compared them with the ampullae of the ambulacral
feet in Echinoderms (1, p. 158) ; Leuckart calls them " Tentakel-Blaschen " (81, p. 197),
and Huxley describes them as basal sacs (9, p. 103). The physiological function of these
basal ampullae is, indeed, the same as those of the ambulacral ampullae in the
Echinoderms. The morphological value, however, is very difficult to make out. It may
be that they are only secondary organs developed from the base of the tentacles, which
originally belong to the siphons. On the other hand it is possible that originally a pair
of siphons has arisen from a common pedicle ; the first siphon has lost the tentacle and
preserved the hepatic villi and the mouth ; the second siphon, on the other hand, has
lost the latter organs and preserved the tentacle. The incipient basal ampulla (fig.
7, to) is much larger than the young tentacle arising from its base (t).

Tentacles (figs. 1, 3, 6, t). — The long tentacles exhibit in all Physalidaa the same
structure, accurately described by Huxley (9, p. 103, pi. x. figs. 11. 12). They are
slender moniliform filaments, or rather ribbon-shaped tubes, and agree essentially with
those of Solatia (PL XXV. fig. 5, t). Only the primary tentacle (fig. 1, t) arises
directly from the base of the protosiphon ; all the other (secondary) tentacles arise from
a common pedicle with a siphon and a palpon (fig. 6) ; or more correctly speaking, the
tentacle (t) and the tentacular palpon (to), closely united, have a common pedicle, which
arises from the same stalk of the cormidium as the siphon. As stated above, the palpon
(the basal sac or basal ampulla, to) bears to the tentacle the same physiological relation
as the ambulacral ampullae of Echinoderms to their feet. In form and structure the
numerous slender accessory tentacles are the same as the single large main tentacle, which
arises from the middle of the ventral group and surpasses the former ten to twenty times
in thickness ; its breadth reaches 3 to 6 mm. or more. Its length is usually more than
a metre, but it may reach in the expanded state ten to twenty metres or even more, as
in Caravella maxima. The ventral side of each tentacle bears a muscular suspensorium
(similar to a ribbon-shaped mesentery), whilst the dorsal side is beset with a series of
very numerous reniform cnidonodes. Each of the latter may .be regarded as a kidney-
shaped tentdlum or lateral branch, since it contains a diverticulum of the tentacular canal.
The thick dorsal wall of this cavity is filled with innumerable spherical cnidocysts.

Gonodendra (PI. XXVI, figs. 3, 6, g, 8). — The corms of all Physalidae are moncecious

REPORT ON THE SIPHONOPHORiE.

347

and the cormidia monoclinic ; each ultimate branch of the clustered gonodendra is
monostylic, since it bears upon the same stalk a single female (f) and numerous male
gonophores (h), intermingled with some gonopalpons (q). The structure of these single
persons is the same as in the other Cystonectse (compare above, p. 313). The number
of gonodendra is usually four to six in the smaller, eight to twelve or more in the larger
species ; they are very richly branched, and arise from a common stalk with the siphons
and palpons (fig. 6). In the largest species each gonodendron bears some thousands of
gonophores. (Compare Huxley, 9, p. 105, pi. x. figs. 14, 15, and Chun, 86, p. 1168.)
The club-shaped androphores (PI. XXVI. fig. 8, h) come to sexual maturity whilst sessile
on the stem, whilst the larger medusiform gynophores (fig. 8,f) become detached and
produce ova as free-swimming Anthomedusae.

Syno'psis of the Genera of Physalidee.

I. Subfamily Arethusid^:.

Pneumatophore simple, without polythala-
mous dorsal crest.

II. Subfamily Caravellid;e.

Pneumatophore provided with a dorsal crest,
which is divided into a series of chambers
by transverse septa.

I

A single large main tentacle,
Several large main tentacles,

A single large main tentacle,
Several large main tentacles,

74a. Alophota.

lib. Arethusa.

75a. Physalia

75b. Caravdla

Genus 74«. Alophota} Brandt, 1835.
Alophota, Bdt., Prodromus, &c, 25, p. 37.

Definition. — Physalidae with a simple vesicular pneumatophore, without dorsa.
polythalamous crest. Siphosome with a single large main tentacle.

The genus Alophota and the following Arethusa compose together the subfamily
Arethusidse, differing from the following subfamily Caravellidse in the absence of the
peculiar polythalamous dorsal crest of the pneumatophore. This characteristic crest is
also wanting in the young larvse of the large-sized Caravellidse ; the small Arethusidse,
therefore, may be regarded as the ancestors of the former, or also as young Caravel-
lidse, which have reached sexual maturity in the larval form (Psedogenesis). In every
case a crestless genus of Arethusidse must have preceded in older times the crested
Caravellidse, much in the same way as the crestless Rataria has preceded the crested
Velella. The crest of the pneumatophore, as an adaptation subservient to sailing, is a
secondary acquisition of later times.

The genus Alophota was established by Brandt (25, p. 37) for a small crestless
Physalid from the Tropical Atlantic. Comparing the good figure which Mertens has left

1 Alophota = Without crest, khi^orx.

348 THE VOYAGE OF H.M.S. CHALLENGER.

of it, I find that it differs from two other forms which I have myself observed living,
Alophota giltschiana, from the Canary Islands (PI. XXVI. figs. 1-3), and Abphota
mertensii, from the Indian Ocean. The description of the latter will be published in
my Morphology of the Siphonophorse.

Alophota giltschiana, n. sp. (PI. XXVI. figs. 1-3).

Habitat. — North Atlantic ; Canary Islands, Lanzerote, December 25, 1866 (Haeckel).

Corni (fig. 3, lateral view of the mature corm. from the right side; fig. 1, a young,
monogastric, larva ; fig. 2, an older, polygastric, larva). — The largest corms observed
which possessed gonodendra at the base of the siphons had a diameter of 15 to 20
mm., and were of a greenish-blue colour. The common trunk and the basal ampullae of
the tentacles were light greenish, the pneumatosaccus, the siphons, and the tentacles
blue, the siphons with numerous black patches — the hepatic villi. The colour of the
ripe gonodendra (placed on the right side) was yellowish. The body of the young
larvae, without gonodendra (figs. 1, 2), was entirely blue-coloured, or with a few greenish
portions here and there. The smallest larva observed (fig. 1) was monogastric, 4 mm.
long and 1 mm. thick, and had a pneumatophore 1 mm. in length. This Cystonida was in
the contracted state very similar to that figured by Huxley of Physalia (9, pi. x. fig. 1).
Pneumatophore. — The expanded float of the ripe corm (fig. 3) is ovate, with sub-
horizontal axis. The apical or anterior pole is pointed and bears the stigma or the
opening for the emission of gas (fig. 3, po). The opposite basal or posterior pole is
rounded and bears the protosiphon, or the primary polypi te of the larva (su), and
attached to its base a single tentacle with a basal ampulla. This distal or primary
cormidium is separated by a broad interval (the basal internode) from the ventral
group of ordinate cormidia, which form a single series in the ventral median line of
the pneumatophore ; they occupy only the middle third of its ventral side, whilst
the anterior third and the posterior third (or the basal internode) are naked and
free, without appendages.

Cormidia. — The number of secondary cormidia which compose the ventral group is
in the specimen figured (fig. 3) four, besides a young one undeveloped. Each cormidium
(fig. 6) is composed of four different organs, arising from a common pedicle, viz., (1) a
blue siphon, with black hepatic villi and a terminal mouth ; (2) a long blue tentacle (t) ;
(3) a light greenish spindle-shaped basal ampulla (to) arising from its base; and (4) a
small clustered monostylic gonodendron (g). The structure of all these parts is the
usual one, as described above (pp. 345-347). The second tentacle and ampulla (counting
from the apex) are far larger than those of the other cormidia. The size of this main
tentacle and of the appertaining central siphon was in a second specimen (bearing six
mature cormidia) comparatively much larger.

REPORT ON THE SIPHONOPHOR^E. 349

Genus 746. Arethusa? Haeckel, 1888.

Definition. — Physalidse with a simple vesicular pneumatophore, without dorsal
polythalamous crest. Siphosome with several large main tentacles of about equal size.

The genus Arethusa was established a century ago (in 1789) by Patrick Browne, for
that gigantic Physalid of the Tropical Atlantic, which is known to the sailors as the
"Portuguese Man-of-War," and which 0. F. Miiller and Gmelin had called Medusa
caravella (afterwards Salacia), the type of our genus Caravella (Genus 756). Since the
generic name Arethusa was afterwards given up and replaced by Lamarck's name Physalia,
we employ here the former for the designation of those Physalidse which agree with
Caravella in the possession of numerous large main tentacles, but differ from it in the
absence of a polythalamous crest on the pneumatophore. Arethusa exhibits, therefore,
the same relation to Caravella as the crestless Alophota bears to the crested Physalia.

Two different species of Arethusa were observed by me ; the first, Arethusa thalia
(from the Indian Ocean), is similar to Alophota giltschiana (PL XXVI. fig. 3), and
exhibits a free interval between the single basal cormidium at the distal end of the
trunk and the central group of loose cormidia on its ventral side. The second species
(inhabiting the Atlantic, and figured in PI. XXVI. figs. 4-8) does not exhibit that interval,
but all the cormidia form together a single large group in the posterior half of the ventral
side of the trunk.

Arethusa challengeri, n. sp. (PL XXVI. figs. 4-8).

Habitat— North Atlantic, Station 354, May 6, 1876; lat. 32° 41' N., long. 36° 6' W.;
surface.

Canary Islands, Lanzerote ; December 1866 (Haeckel).

Corm (fig. 4, lateral view of the mature corm from the right side, in the expanded
state ; fig. 5, from the left side, in the contracted state). — The largest corms observed which
possessed gonodendra at the base of the siphons had a length of 40 mm. to 50 mm.
The colour of the corm was greenish-blue ; the common trunk and the basal arnpullse
light greenish, their tops often reddish ; the siphons dark blue, with black villi, their
proboscis often reddish ; the tentacles partly blue, partly purple. The clustered
gonodendra (placed on the right side) had a reddish colour.

Pneumatophore (figs. 4, 5, pf). — The float filled with ah' occupies the greatest part of
the trunk ; it exhibits as usual very different forms, according to the variable state of
contraction. The longitudinal axis is subhorizontal. The outer wall (pneumatocodon)
is separated from the inner wall (pneumatosac) by the cavity of the trunk, which is
rather wide and sacciform in the posterior half, and especially on the ventral side. The

1 Arethusa = ' AciSovau, a Nymph, daughter of Nereus.

350 THE VOYAGE OF H.M.S. CHALLENGER.

apex of the float (or the anterior top) exhibits a beak-shaped, very mobile apophysis, the
apical rostrum ; and at the upper side of its base is the stigma, or the air-pore (po).

Cormidia-. — The posterior half of the ventral side of the trunk bears a continuous series
of densely clustered cormidia, of the same shape as in the younger and smaller forms
of Caravella maxima. Each fully developed cormidium (fig. 6) bears on a common
short cylindrical pedicle (ap) four different organs, viz., (1) a blue siphon with black
hepatic villi (sv) and a distal mouth (so); (2) a long blue or red tentacle beset with a series
of reniform cnidonodes (t) ; (3) a slenderly spindle-shaped, light greenish basal ampulla
(to) arising from its base; and (4) a clustered, yellowish or reddish, monostylic gono-
dendron of the usual composition (p. 313). The structure of all these parts is the same
as in the other Physalidee, as described above (pp. 345-347).

A variable number of main tentacles (usually six to eight) are far larger than the
others, besides the young and undeveloped ones. The primary basal siphon (or the
protosiphon, fig. 4, su), at the distal end of the trunk, is of the same form and size as
the secondary siphons (in the ventral side), but is sterile and bears no gonodendron.
Between it and the lowermost (oldest) secondary siphon is a group of small pyriform
palpons (without tentacles). This group fills the interval (or the basal internode),
which is free and naked in Alophota (PI. XXVI. fig. 3).

Genus 75a. Physalia,1 Lamarck, 1816.
Physalia, Lamarck, Hist. nat. des anim. sans vert., torn. ii. p. 478.

Definition. — Physalidse with a polythalamous crest on the dorsal side of the large
vesicular pneumatophore. Siphosome with a single large main tentacle.

The genus Physalia and the following Caravella make up together the subfamily
Caravellidse, differing from the preceding subfamily Arethusidae in the possession of that
peculiar dorsal crest of the pneumatophore, which is divided by numerous vertical
transverse septa into a series of air-filled triangular chambers. All Physabdas belonging
to the Caravellidae attain a far larger size and bear a far greater number of organs in their
loose cormidia than the preceding Arethusidae. The genus Physalia, in the stricter
definition here offered, comprises the greater number of species hitherto described. It
bears only a single large main tentacle, much longer and thicker than the numerous
accessory tentacles, and differs by this constant character from the following Caravella,
provided constantly with a greater number of subequal strong main tentacles (usually ten
to twenty or more). Physalia bears therefore the same relation to Caravella as the
crestless Alophota does to Arethusa.

The accurate distinction and sharp definition of the numerous species of Physalia which
have been described is a very difficult task, owing partly to the numerous transitional

1 Phrjsalia = Sea-bladder, tpvvct, SlKih.

REPORT ON THE SIPHONOPHOR^. 351

forms, which connect the different " good species " of this transformistic group, partly
to the great confusion of the voluminous literature on this subject. Most authors have
founded their specific distinctions upon slight differences in the variable form of the very
contractile pneumatophore and insignificant varieties of colour. The accurate anatomical
examination of the siphosome, the composition of the cormidia, and the relations of the
different clustered medusomes has been much neglected, and requires a further more
critical comparison (compare Huxley, 9, p. 99, and Chun 83, p. 557). Judging from the
extended observations of numerous Physalige collected in different seas which I have
been able to compare recently, I think that the following four species of Physalia may
be distinguished provisionally: — (l) Physalia pelagica (South Atlantic); (2) Physalia
cornuta (Indian Ocean); (3) Physalia utriculus (Pacific); and (4) Physalia megalista
(Indian Ocean and South Atlantic).

Physalia megalista, Lamk. (Peron, 14, pi. xxix. fig. 1), differs from the three other
species in the complete union of all the cormidia, as in Caravalla maxima; there is
wanting here the free interval which separates the small basal cormidium (on the distal
end of the trunk) from the main mass of clustered cormidia on the ventral side of the
pneumatophore. This interval between the two groups of cormidia (the smaller posterior
and the larger anterior), as well as the composition of these cormidia, is different in the
three other species of Physalia ; the structure, too, of the pneumatophore, the number
of chambers in its crest, and the mode of attachment of the appendages to the trunk,
seem to offer marks for a more accurate distinction of these species. (Compare the
figures of the Southern Atlantic Physalia pelagica by Eysenhardt, 77, p. 45, Tab. xxxv.
fig. 2 ; of the Indian Physalia cornuta by Tilesius, 76, p. 42 ; and of the Pacific Physalia
utriculus by Eschscholtz, 1, p. 163, Taf. xiv. figs. 2, 3 ; and in Cuvier's Regne Animal
Illustre, Zoophytes, pi. 58, fig. 4.)

Genus 75b. Caravella,1 Haeckel, 1888.

Definition. — Physalidas with a polythalamous crest on the dorsal side of the large
vesicular pneumatophore. Siphosome with several large main tentacles of about equal
size.

The genus Caravella comprises those Physalidse which agree in the possession of a
polythalamous crest on the dorsal side of the large pneumatophore with the preceding
true Physalia (s. restr.), but differ from them in the possession of numerous large main
tentacles, besides a great number of small accessory tentacles (or palpacles). Caravella
exhibits therefore the same relation to Physalia which the crestless Arethusa bears to
Aloplxota. The cormidia are in Caravella polygastric and loose ; the number of siphons

1 Caravella, the old name of Physalia as usually employed by the Italian and Spanish sailors [Medusa caravella,
Linne).

352 THE VOYAGE OF H.M.S. CHALLENGER.

and tentacles very great ; usually ten to twenty very large tentacles are intermingled with
forty to sixty or more small ones. The size, too, of the pneumatophore is in this genus
larger than in all other Physalidse and in all Siphonophoras in general; its length attains
in the largest specimens, fully expanded, 20 to 30 cm. or even more, its greatest breadth
8 to 10 cm.; the largest tentacles, fully expanded, attain a length of 20 to 30 metres
or even more (40 to 50 feet, L. Agassiz, 36, p. 336).

Two species only of Caravella may be distinguished in our present incomplete know-
ledge of this genus, both inhabiting the Atlantic Ocean. The smaller species is Caravella
gigantea { = Physalia gigantea, Bory, Physalia cystisoma, Lesson, partim) ; it occurs
sometimes in the Southern Atlantic, and seems to be transported from there occa-
sionally by westerly winds into the Indian Ocean. Captain Eabbe collected it between
Madagascar and the Cape of Good Hope. All parts of the body are smaller and more
delicate than in the following species. The number of large main tentacles is four to
eight, rarely more. But the principal difference is found in the isolated position of the
basal cormidium, which is placed at the distal end of the trunk. It is isolated by a wide
interval from the voluminous main mass of clustered cormidia, which occupies the smaller
posterior half of the ventral side of the trunk. The predominant colour seems to be
in Caravella gigantea more purple and violet, in Caravella maxima more blue and
greenish ; it is subject, however, to many variations.

The larger species, and the largest of all the Physalidse, is the well-known Cara-
vella maxima, which inhabits in great numbers the Tropical and Subtropical Atlantic,
and especially the Gulf Stream. I observed it in great numbers during my residence in
the Canary Islands, in December 1866 and January 1867, and also returning from there, in
the Straits of Gibraltar, particularly in the Bay of Algesiras (in March 1867). It is also
occasionally driven by westerly winds into the Mediterranean, which it seems not to
inhabit permanently ; several specimens are observed in single years on the shores of
Italy (Naples, Messina, &c). Caravella maxima has been described as Medusa caravella
by O. F. Miiller and Gmelin, as Physalia caravella by Eschscholtz (1, p. 160, Taf. xiv.
fig. 1). Numerous later authors have figured it under the name Physalia arethusa, as
for example Tilesius, Chamisso, Olfers (79, Taf. i., ii.), and L. Agassiz (36, pi. xxxv.).
Lamarck and Lesson (3, pi. xi.) call it Physalia pelagica. (For the synonymy and
history of this celebrated species, compare Olfers and Lesson, loc. cit.) Caravella
maxima is easily distinguished from the allied Caravella gigantea by the union of the
basal cormidium with the other corrnidia, all forming; together a single clustered mass of
crowded appendages, which covers the greater (posterior) half of the ventral side down
to its basal apex. On its motions and habits, compare Olfers (79) and L. Agassiz (36;
p. 336). The young larva? of Caravella maxima, which I observed at Christmas
1866 in Lanzerote, are very similar to those figured in PL XXVI. figs. 1, 2 (Cystonula).

BIBLIOGRAPHY OF THE SIPHONOPHORiE.

A. Larger works, treating of the whole class or a great part of the different families ;
all of high systematic importance and permanent historical value : —

1. 1829. Eschscholtz, J. Friedrich, System der Acalephen, eine ausfiihrliche Beschieibung aller meduse-

nartigen Strahlthiere. Dritte Ordnung, Ebhrenquallen, Siphonophorae, pp. 121-180, Taf. xii.-xvi.

2. 1833. Quoy et Gaimard, Voyage de 1' Astrolabe, Zoologie, torn. iv. pp. 49-107, pis. i.-v.

3. 1843. Lesson, B. P., Histoire naturelle des Zoophytes, Aealephes (Paris), pp. 425-529. (Compilation.)

4. 1853. Kolliker, Albert, Die Sehwimmpolypen oder Siphonophoren von Messina, 96 pp.; with 12 plates.

5. 1853. Leuckart, Eudolf, Die Siphonophoren, eine Zoologische Untersuchung, 95 pp.; with 3 plates.

6. 1854. Vogt, Carl, Sur les Siphonophores de la mer de Nice, 164 pp.; with 21 plates.

7. 1854. Gegenbaur, Carl, Beitrage zur niiheren Kenntniss der Sehwimmpolypen (Siphonophoren).

Zeitsc.hr. f. wiss. ZooL, Bd. v. pp. 285-343, Taf. xvi-xviii.

8. 1854. Leuckart, Eudolf, Zur niiheren Kenntniss der Siphonophoren von Nizza. Archiv f. Naturgesch.,

Jahrg. xx. pp. 249-377, Taf. xi.-xiii.

9. 1859. Huxley, Thomas H., The Oceanic Hydrozoa. A description of the Calycophoridae and Physophoridae,

with a general introduction; 144 pp. and 12 plates.

10. 1859. Gegenbaur, Carl, Neue Beitrage zur naheren Kenntniss der Siphonophoren. Nova Acta Acad.

Nat. Curios., torn, xxvii. pp. 332-424, Tab. xxvii.-xxxiii.

B. Older works, with scattered observations on single forms, all before Eschscholtz
(1775-1829) : —

11. 1775. Forskal, Petrus, Descriptiones animalium quae in itinere orientali observavit, post mortem

edidit Carsten Niebuhr. Icones rerum naturalium 1776 (Porpita, Velella, Physophora,
A fhorybia, Rhizophysa).

12. 1802. Bosc, Histoire naturelle des vers.

13. 1804. Bory de St. Vincent, Voyage dans les quatre principales iles des mers d'Afrique, pi. liv. (Physalia,

Velella).

14. 1807. Peron et Lesueur, Voyage de Decouvertes aux terres australes. Mollusques et Zoophytes.

pi. xxix. (Physalia, Rhizophysa, Physophora, Stephanomia), pi. xxx. (Velella), pL xxxi.
(Porpita).

15. 1813. Lesueur, Memoire sur quelques nouvelles especes de Mollusques et Eadiaires. Journ. de Physique,

torn, lxxvii. pp. 119-124.

16. 1821. Chamisso and Eysenhardt, De Animalibus quibusdam e classe Vermium. Nova Acta Acad. Nat.

Curios., torn. x. Tab. xxxii.

17. 1823. Otto, Beschreibung einiger neuer Mollusken und Zoophyten (Pyramis, Gleba). Nova Acta Acad.

Nat. Curios., torn. xi. p. 306, Tab. xlii.

18. 1823-1829. Delle Chiaje, Meaiorie sulla storia e notomia degli animali senza vertebre di Napoli.
(zool. chall. exp. — part lxxvii. — 1888.) Hbhh 45

354 THE VOYAGE OF H.M.S. CHALLENGER.

19. 1824. Quoy et Gaimard, Voyage do 1'Uranie et de la Pbysicienne, Zoologie, p. 577, pis. lxxxvi., Ixxxvii.

20. 1827. Qooy et Gaimard, Observations zoologiques faites a bord de r Astrolabe dans le Detroit de Gibraltar.

Ann. d. Sci. Nat. (Zool.), torn. x. (German translation, Okeris Isis, 1828, Bd. xxi. p. 330, Taf.
iii.-v.).

21. 1825. Eschscholtz, J. Friedrich, Bericht liber die zoologiscbe Ausbeute der Reise. Oken's Isis, p. 743,

Taf. v. figs. 14-17.

C. Works treating of different single parts of the class, or of its general organisation,
all after Eschscholtz (1830-1888) :—

22. 1830. Lesson, R. P., Voyage de la Coquille, Zoologie, tom. 2, ii., Zoophytes, chap. xv. pis. iv.-vii., xiv.-xvii.

23. 1834. Meyen, F. J. F., Beitrage zur Zoologie. Nova Ada Acad. Nat. Curios., tom. xvi., Suppl. i.

24. 1834. Blainville, Ducrotay de, Manuel dActinologie ou de Zoophytologie, pp. 111-140.

25. 1835. Brandt, J. Friedrich, Prodromus descriptions animalium ab H. Mertensio in orbis terrarum

circumnavigatione observatorum, pp. 31-41.

26. 1840. Milne-Edwards, Sur les Acaleph.es hydrostatiques. Comptes rendus, tom. x. p. 780; lTnstitut, tom.

viii. p. 175.

27. 1846. Sars, Michael, Fauna littoralis Norvegiaj, Heft i. pp. 31-46, Taf. v.-vii. (Agalmopsis, Diphyes).

Heft iii. (1877) p. 32, Taf. v., vi. (Physophora).

28. 1848. Vogt, Carl, Ocean und Mittelmeer. Reisebriefe. Bd. i. pp. 309-330.

29. 1851. Huxley, Thomas H., An account of Researches into the Anatomy of the Hydrostatic AcaJ.epb.se.

Rep. Brit. Assoc, p. 78.

30. 1851. Huxley, Thomas H., Uber die Sexual-Organe der Diphyiden und Physophoriden. Mailer's

Archiv f. Anat. u. Physiol., p. 380.

31. 1854. Gegenbaur, Carl, tjber einige niedere Seethiere. Zeitschr. f. wiss. Zool., Bd. v. p. 103.

32. 1859. McCrady, John, Gymnophthalmata of Charleston Harbour. Proe. Elliot Soc. Nat. Hist.

Cliarleston, vol. i. pp. 139-147 (Velellidas), pp. 169-181 (Siphonophoras.)

33. 1861. Keferstein und Ehlers, Zoologiscbe Beitrage. I. Die Siphonophoren von Neapel und Messina,

pp. 1-34, Taf. i.-v.

34. 1860. Claus, Carl, Uber Physophora hydrostatica, nebst Bemerkungen iiber andere Siphonophoren.

Zeitschr. f. wiss. Zool., Bd. x. p. 295, Taf. xxv.-xxvii.

35. 1863. Claus, Carl, Neue Beobachtungen uber die Structur und Entvvickelung der Siphonophoren.

Zeitschr. f. iviss. Zool., Bd. xii. p. 536, Taf. xlvi.-xlviii.

36. 1862. Agassiz, Louis, Contributions to the Natural History of the United States of America. Vol. iv.

pp. 333-336, and pp. 366-372. (Catalogue of the genera and species described.)

37. 1865. Agassiz, Alexander, North American Acalepha?. Illust. Catal. Mus. Comp. Zool., Harvard Coll.,

No. II., pp. 199-218. (Nanomia cara, p. 200.)

38. 1869. Haeckel, Ernst, Uber Arbeitstheilung in Natur und Menschenleben. (Anthemodes canariensis.)

39. 1871. Muller, P. E., Jagttagelser over nogle Siphonophorer (Calyconeet»). Naturhist. Tidsskr.

Kj0benhavn, 2 R., Bd. vii. p. 261, Taf. xi.-xiii.

40. 1878. Studer, Theodor, Uber Siphonophoren des tiefen Wassers (Bathyphysa, Rhizophysa, &c).

Zeitschr. f. wiss. Zool., Bd. xxxi. p. 1, Taf. i.-iii.

41. 1879. Eewkes, J. Walter, Notes on Rhizophysa filiformis and Abyla pentagona. Proc. Boston Soc. Nat.

Hist., vol. xx. pp. 292, 318.

42. 1880. Fewkes, J. Walter, The Siphonophores. I. Agalma. American Naturalist, vols. xiv. and xv.

(1881). II. Diphyes, Ibid., vol. xvi. (1882), vol. xvii. (1883), vol. xviii. (1884).

43. 1881. Fewkes, J. Walter, Studies of the Jelly-Fishes of Narragansett Bay. Bull. Mus. Comp. Zool.,

vol. viii. No. 8, p. 163.

44. 1881. Fewkes, J. Walter, Notes on Acalephs from the Tortugas, kc. Bull. Mus. Comp. Zool.,

vol. ix. No. 7, pp. 264-276, pis. v., vi.; No. 8, p. 302.

REPORT ON THE SIPHONOPHOR^E. 355

45. 1884. Fewkes, J. "Walter, Report on the Medusae collected by the U.S. Fish. Com. Steamer "Albatross,"

in the Region of the Gulf Stream, in 1883, 1884. Siphonophorfe. Rep. U.S. Fish Com., part xi.
p. 599; part xii. pp. 963-975, pi. x. (Ehizophysa, Pterophysa, Angelopsis ; Haliphyta magnified,
only mentioned).

46. 1881. Chun, Carl, Das Nervensystem der Siphonophoren. Zool. Anzeiger, Jahrg. iv. p. 107.

47. 1882. Chun, Carl, Die Gewebe der Siphonophoren. Zool. Anzeiger, Jahrg. v. p. 400.

48. 1887. Chun, Carl, Zur Morphologic der Siphonophoren. I. Der Bau der Pneumatophoren. Zool.

Anzeiger, Jahrg. x. pp. 511, 529.

49. 1882. Korotneff, Alexander, Zur Kenntnissder Siphonopboren (Histologic). Zool. Anzeiger, Jahrg. v.

p. 360 ; Jahrg. vi. p. 492 (1883).

50. 1884. Korotneff, Alexander, Zur Histologie der Siphonophoren. Mittheil. a. d. Zool. Stat. Neapel,

Bd. v. p. 229, Taf. xiv.-xix.

D. Monographs and smaller papers on single Disconectse : —

51. 1833. Grant, Robert, On the Velella limbosa. Proe. Zool. Soc. Land., vol. i. p. 14.

52. 1841. Costa, O. G., Note sur lAppareil vasculaire de la Velella (Armenistarium). Ann. d. Sci. Nat.

(ZooL), ser. 2, torn. xvi. p. 187.

53. 1845. Hollard, H., Recherches sur l'organisation des Velelles. Ann. d. Sci. Nat. (Zool.), ser. 3, torn. iii.

p. 248.

54. 1848. Krohn, August, Notiz iiber die Anwesenheit eigenthiimlicher Luftkankle bei Velella und Porpita.

Archivf. Naturgesch., Jahrg. xiv. p. 30.

55. 1863. Pagenstecher, H. A., Zur naheren Kenntniss der Velellidenform Rataria, nebst Betrachtungen

iiber die Velelliden in Allgemeinen. Zeitschr. f. wiss. Zool., Bd. xii. p. 496, Taf. xl., xli.

56. 1883. Conn and Beyer, The Nervous System of Porpita. Stud. Biol. Lab. Johns Hopkins Univ.,

vol. ii. p. 433.

57. 1883. Agassiz, Alexander, The Porpitidae and Velellidse. Mem. Mm. Oomp. Zool., vol. viii., 16

pp., 12 plates. (Porpita linnaeana, with 6 plates, and Velella mutica, with 6 plates.)

58. 1884. Bedot, Maurice, Recherches sur le foie des Velelles. Comptes rendus, torn, xcviii. p. 1004.

59. 1884. Bedot, Maurice, Recherches sur l'Organe central et le System vasculaire des Velelles. Recueil

Zool. Suisse, torn. i. p. 491, pis. xxv., xxvi.

60. 1885. Bedot, Maurice, Contribution a lV'tude des Velellides. Recueil Zool. Suisse, torn. ii. p. 237, pi. ix.

61. 1885. Bedot, Maurice, Sur l'Histologie de la Porpita mediterranea. Recueil Zool. Suisse, torn. ii. p. 189.

62. 1886. Bedot, Maurice, Recherches sur les cellules urticantes (Velellides, Physalides). Recueil Zool.

Suisse, torn. iv. p. 51, pis. ii., iii.

E. Monographs and smaller papers on single Calyconectse : —

63. 1830. Lesson, R. P., Centurie Zoojogique, pis. lv.-lvii. (Diphyes).

64. 1841. Htndman, G. C, The genus Diphya on the Coast of Ireland. Ann.and May. Nat. Hist., vol. vii. p. 164.

65. 1844. Will, J. G. Friedrich, Horae tergestinse (Acalephen bei Triest). (Calycophoridse.) pp. 76-83,

Taf. ii. figs. 22-31.

66. 1855. Huxley, Thomas H, On the Anatomy of Diphyes and on the Unity of Composition of the

Diphyidae and Physophoridae. Proc. Linn. Soc. Lond., vol. ii. pp. 67-69.

67. 1851. Busch, Wilhelm, Beobachtungen iiber Anatomie und Entwicklung einiger wirbellosen Seethiere

(Berlin).

68. 1854. Gegenbaur, Carl, Uber Diphyes turgida, nebst Bemerkungen iiber Schwimmpolypen

(Calycophoren). Zeitschr. f. wiss. Zool., Bd. v. p. 442, Taf. xxiii.

69. 1869. Pagenstecher, H. A., Eine neue Entwickelungsweise bei Siphonophoren (Monophyes). Zeitschr.

f. wiss. Zool, Bd. xix. p. 244, Taf. xxi.

70. 1874. Claus, Carl, Die Gattung Monophyes und ihr Abkijmmling Diplophysa. Schrift. Zool. Inst.

Wien, p. 25, Taf. iv.

356 THE VOYAGE OF H.M.S. CHALLENGER.

F. Monographs and smaller papers on single Physonectse : —

71. 1841. Milne-Edwards, Description de la Stepbanomia contorta et de la Stephanomia prolifera. Ann. d.

Sci. Nat. (Zool.), torn. xvi. p. 217, pis. vii.-x.

72. 1843. Philippi, R. A., Uber den Bau der Physophoren, &c. Archiv f. Anat. u. Physiol., pp. 58-G7, Taf. v.

73. 1857. Dana, J. D., Crystallomia polygonata. Mem. Amer. Acad. Arts and Sci., vol. vi. part i. p. 459.

74. 1878. Claus, Carl, Uber Halistemnia tergestinurn, nebst Bemerkungen iiber den feineren Bau der

Physophoriden. Arb. Zool. Inst. Wien, Bd. i. pp. 1-56, Taf. i.-v.

75. 1879. Claus, Cabl, Agalmopsis utricularia, eine neue Siphonopbore des Mittelmeeres. Arb. Zool. Ins/.

Wien, Bd. ii. pp. 190-201, Taf. xviiL

G. Monographs and smaller papers on single Cystonectee : —

76. 1813. Tilesius, W. G., Uber Pbysalia. Naturhist. Friichte der Erdumsegelung von Krusenstern.

77. 1821. Eysenhabdt, K. W., Uber die Seeblasen. Nova Acta Acad. Nat. Curios., torn. x. Tab. xxxv.

78. 1824. Eichwald, E. v., Observationes nonnulke circa fabricam Physalise. Mem. Acad. Scd. St. Peters-

burg, tom. ix. pp. 453-472.

79. 1831. Olfers, L F. v., Uber die grosse Seeblase (Physalia arethusa), &c. Abhandl. d. k. Akad. d. Wi™.

Berlin, pp. 155-200.

80. 1855. Huxley, Thomas H., On the Anatomy of Physalia. Proc. Linn. Soc. Lond., vol. ii. pp. 3-5.

81. 1851. Leuckart, R., Uber den Bau der Pbysalien und der Rohrenquallen im Allgeineinen. Zeitschr. f.

wiss. Zool., Bd. iii. pp. 189-212, Taf. vi. figs. 1-6.

82. 1854. Quatrefages, A. de, Memoire sur l'organisation des Physalies. Ann. d. Sci. Nat. (Zool.), ser. 4,

tom. ii. pp. 107-142.

83. 1887. Chun, Carl, Uber die postembryonal Entwickelung von Physalia. Zool. Anzeiger, Jahrg. x.

pp. 557, 574.

H. Ontogeny ; Papers on the individual development of Siphonophora3 : —

84. 1869. Haeckel, Ernst, Entwicklungsgeschichte der Siphonophoren. Eine von der Utrechter Gesell-

scbaft fiir Kunst und Wissenschaft gekrb'nte Preisschrift. 120 pp. and 14 Plates.

85. 1874. Metschnikoff, Elias, Studien iiber die Entwicklung der Medusen und Siphonophoren-

Zeitschr. f. iviss. Zool., Bd. xxiv. p. 35, Taf. vi.-xii.

86. 1882. Chun, Carl, Uber die cyclische Entwickelung und die Verwandtschafts-Verhaltnisse der Siphono-

phoren. I. Sitzungsb. d. k. Akad. Wiss. Berlin, p. 1 155, Taf. xvii.

87. 1885. Chun, Carl, Uber die cyclische Entwickelung der Siphonophoren. II. Sitzungsb. d. k. Akad.

Wiss. Berlin, p. 511, Taf. ii.

88. 1886. Chun, Carl, Uber Bau und Entwicklung der Siphonophoren. III. Sitzungsb. d. k. Akad. Wiss.

Berlin, p. 681.

89. 1885. Fewkes, J. Walter, On the development of Agalma ( = Agalmopsis catena). Bull. Mus. Comp,

Zool., vol. xi. p. 239, pis. i.-iv.

I. Manuals and other Works respecting Siphonophorse : —

90. 1816. Lamabck, Jean, Hist. nat. des anim. sans vert., ed. 1, 1816, tom. ii.

91. 1817. Cuvier, G., Le regne animal, ed. 1, 1817, part iv.

92. 1870. Geqenbaur, Carl, Grundziige der vergleichenden Anatomie, p. 147, &c.

93. 1881. Perrier, Edmond, Les Colonies animales et la formation des Organismes. Chap, v., Siphonophorcs.

94. 1882. Bedot, Maurice, Sur la faune des Siphonophores du golfe de Naples (List of 19 species). Mitiheil.

a. d. Zool. Stat. Neapel, Bd. iii. pp. 121-123.

95. 1888. Haeckel, Ernst, System der Siphonophoren, auf phylogenetischer Grundlage entworfen.

Jenaische Zeitschri/t, Bd. xx. p. 1. (A separate edition of this paper, the general part of which
is translated as the Introduction to this Report, was published in December 1887.)

LIST OF FAMILIES, GENERA, AND SPECIES.

N.B. — This list is a complete catalogue of all the genera and species of Siphonophone hitherto described
with sufficient evidence (from 1775 to 1888); the doubtful or insufficiently characterised species are marked
by a query. Those new species, which are followed by the words " Morph. Siphon.," will be described after-
wards in my Morphologie der Siphonophoren.

Order I. DISCONECT^, Haeckel (System, 95, p. 29).

Family I. D I s c A L I v>M, Haeckel (System, 95, p. 29).
Genus 1. Discalia, Hkl. (95, p. 29).

1. Discalia medusina, Hkl. (Report, p. 46, PI. XLIX. figs. 1—6). South Pacific, Station 288.

2. Discalia primordialis, Hkl. (Report, p. 46). Tropical Pacific, Station 274.

Genus 2. Disconalia, Hkl. (95, p. 30).

3. Disconalia gastroblasta, Hkl. (Report, p. 48, PI. XLIX. figs. 7-12 ; PI. L.). South Pacific,

Station 181.

4. Disconalia pectyllis, Hkl. (Morph. Siphon.). Indian Ocean, Station 157.

5. Disconalia ramifera, Hkl. (?) ( = Porpita ramifera, Eschscholtz ?, 1, p. 178, Taf. xvi fig. 3).

Tropical Pacific (?).

Family II. P o R p I t i dje, Brandt (25, p. 40).
Genus 3. Porpalia, Hkl. (95, p. 30).

6. Porpalia prunella, Hkl. (Report, p. 58, PL XLVIIL). Tropical Pacific, Station 222.

7. Porpalia gldbosa, Hkl. ( = Porpita globosa, Esch., 1, p. 178, Taf. xvi. fig. 4). Tropical Atlantic

(near the Cape Verde Islands).

:].">S THE VOYAGE OF H.M.S. CHALLENGER.

Genus 4. Porpema, Hkl. (95, p. 30).

8. Porpema medusa, Hkl. (Eeport, p. 61, PL XLVIL). South Atlantic, Station 327.

9. Porpema lenticula, Hkl. (Morph. Siphon.). Indian Ocean.

10. Porpema pileata, Hkl. (Morph. Siphon.). South Pacific (coast of Chili).

Genus 5. PorpiteUa, Hkl. (95, p. 30).

11. PorpiteUa pcctanthis, Hkl. (Eeport, p. 64, PL XLVL). North Pacific, Station 244.

12. PorpiteUa ccerulea, Hkl. ( = Porpita ccerulea, Esch., 1, p. 179, Taf. xvi. fig. 5). Tropical

Pacific.

13. PorpiteUa radiata, Hkl. ( = Porpita raeliata, Brandt, 25, p. 40). Tropical Pacific.

Genus 6. Porpita, Lamarck (90, p. 483).

14. Porpita mediterranea, Esch. (1, p. 177). Oldest description and figure by Forskal (11, p. 103,

Tab. xxvi. fig. L, 1). Best description and figure by Kolliker (4, p. 57, Taf. xii.).
Mediterranean.

15. Porpita linn&ana, Lesson (3, p. 588). Best description and figure by Alex. Agassiz (57, p. 12,

pis. vii.-xii.). North Atlantic.

16. Porpita umbella, Esch. (1, p. 179= Porpita gigantea, Peron, 14, pi. xxxi. fig. 6). Tropical

Atlantic (?).

17. Porpita indica, Hkl. (= Porpita liitheanal, Brandt, 25, p. 41). Indian Ocean.

18. Porpita fungia, Hkl. (Report, p. G7, PL XLV.). North Pacific, Stations 253 to 255.

19. Porpita pacifica, Lesson (22, pi. vii. fig. 3). Tropical Pacific (near Peru) (?).

20. Porpita australis, Hkl. (Morph. Siphon.). South Pacific.

Family III. Velellid^, Esch. (1, p. 165).
Genus 7. Rataria, Esch. (1, p. 166).

21. Rataria cristata, Hkl. (Report, p. 79, PL XLIV.). Tropical Atlantic, Station 348.

22. Rataria mitrata, Esch. (1, p. 168, Taf. xvi. fig. 2). Tropical Atlantic, off the Cape Verde

Islands (?).

23. Rataria cordata, Esch. (1, p. 167, Taf. xvi. fig. 1). North Atlantic (?).

Genus 8. Velella, Lamarck (90, p. 481).

24. Velella spirans, Esch. (1, p. 172= Velella limbosa, Lamk., 90). Oldest description and

figure by Forskal (11, p. 104, Tab. xxvi. fig. k). Best description and figure by Kolliker
(4, p. 46, Taf. xi. figs. 9-15). Mediterranean.

REPORT ON THE SIPHONOPHOR^. 359

25. Vclclla caurina, Esch. (1, p. 173, Taf. xv. fig. 2). North Atlantic.

26. Velella scaphidia, Peron et Lesueur (14, p. 44, pi. xxx. fig. 6). Tropical and South Atlantic,

Stations 346-352.

27. Velella oblonga, Chamisso (16, p. 363, Tab. xxxii. fig. 2). Northern and Tropical Pacific

(Stations 229-237).

28. Velella pacifica, Esch. (1, p. 174, Taf. xiv. fig. 4). North Pacific.

29. Velella patella, Brdt. (25, p. 38). Tropical Pacific (Stations 265-279).

30. Velella cyanea, Lesson (22, p. 54, pi. vi. figs. 3, 4). South Pacific (?).

Genus 9. Armenista, Hkl. (Report, p. 83).

31. Armenista mutica, Hkl. ( = Velella mutica, Lamk.). Best description and figures by Alex.

Agassiz (57, p. 2, pis. i.-vi.). North Atlantic.

32. Armenista sigmoides, Hkl. (Report, p. 84, PI. XLIIL). Tropical Atlantic and South Atlantic,

Station 346.

33. Armenista indica, Hkl. (= Velella indica, Esch., 1, p. 175, Taf. xv. fig. 5). Indian Ocean.

34. Armenista antarctica, Hkl. (= Velella antarctica, Esch. = Velella sinistra, Chamisso, 16,

p. 363, Tab. xxxii. fig. 1). Indian Ocean, Antarctic Ocean, Cape of Good Hope.

35. Armenista lata, Hkl. ( = Velella lata, Chamisso, 16, p. 364, Tab. xxxii. fig. 3). North Pacific.

36. Armenista lobata, Hkl. (Morph. Siphon.). South Pacific (?).

Order II. CALYCONECT^E, Haeckel (System, 95, p. 31).
Family IV. Eudoxid*, Hkl. (System, 95, p. 32).

Genus 10. Diplophysa, Ggbr. (7, p. 291).

37. Diplophysa inermis, Ggbr. (7, p. 291, Taf. xvi. fig. 3 = Eudoxia of Sphxronectes gracilis, Hkl.).

Mediterranean.

38. Diplophysa hollikeri, Hkl. (Report, p. 108) ( = Eudoxia of Sphueronectes kollikeri, Hxly.).

Indian Ocean and Tropical Pacific, Station 274 (?).

Genus 11. Eiuloxella, Hkl. (Report, p. 108).

39. Eudoxella galea, Hkl. (Report, p. 108, PI. XXXII.). Tropical and Subtropical Atlantic (?).

40. Eudoxella didymu, Hkl. (Morph. Siphon.). Tropical Atlantic, Station 343 (?).

Genus 12a. Cticubalus, Blainv. (24, p. 130).

41. Cucubcdus esehscholtzii, Hkl. ( = Eudoxia esehscholtzii, Busch, 67, p. 33, Taf. iv., v.; Chun,

86, Taf. xvii. fig. 3). Mediterranean.

42. Cucubaliu, pyramidalis, Hkl. ( = Ersiea pyramiclalis, Will, 65, Taf. ii.). Mediterranean,

Atlantic, Stations 348, 352 (?).

43. Cucubalus cordiformis, Quoy et Gaim. (2, pi. iv. pp. 24-27). Tropical Pacific (?).

360 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 12b. Cucullus, Lesson (3, p. 458).

44. Cucullus campanula, Hkl. ( = Eiuloxia campanula, Leuckart, 5, p. 43, Taf. iii. figs. 16—20).

Mediterranean.

45. Cucullus gegcnbauri, Hkl. (= Eudoxia mcssanensis, Ggbr., 7, Taf. xvi. fig. 4). Mediterranean.

46. Cucullus subtilis, Hkl. (=Hrssea clongata, Will, 65, p. 82, Taf. ii. fig. 30). Mediterranean.

47. Cucullus elongatus, Hkl. (Morph. Siphon.) ( = Eudoxia clongata, Hkl.). Atlantic.

48. Cucidlus lessonii, Hkl. ( = Eudoxia lessonii, Esch., 1, p. 126, Tab. xii. fig. 2). Tropical Pacific.

49. Cucullus gracilis, Hkl. (Morph. Siphon.) (= Eudoxia bojani, Hxly., 9, p. 59, pi. iii. fig. 7).

Indian Ocean.

Genus 13. Ctiboides, Quoy et Gaimard (20, p. 19).

50. Cuboides vitreus, Quoy et Gaim., 20, pi. ii. E, figs. 1—3. Mediterranean.

51. Cuboides crystallus, Hkl. (Report, p. 112, PI. XLIL). Tropical and Subtropical Atlantic,

Station 352.

52. Cuboides vogtii, Hkl. ( = Cuboides vitreus, Hxly., 9, p. 63, pi. iv. fig. 5). Tropical Pacific.

53. Cuboides nacella, Hkl. (Morph. Siphon.). Indian Ocean.

Genus 14. Amphiroa, Blainv. (24, p. 133).

54. Amphiroa trigona, Hkl. ( = Eudoxia trigonie, Ggbr., 10, Taf. xxviii. figs. 9-12). Mediterranean.

55. Amphiroa carina, Hkl. (Report, p. 114, PI. XXXVL). Tropical Atlantic, Station 348.

56. Amphiroa alata, Hxly. (9, p. 64, pi. v. fig. 1). Indian Ocean and Tropical Pacific.

57. Amphiroa angidata, Hxly. (9, p. 64, pi. v. fig. 2). South Pacific (?).

Genus 15. Sphenoides, Huxley (9, p. 61).

58. Sphenoides tetragona, Hkl. (Morph. Siphon.). Indian Ocean.

59. Sphenoides obeliscus, Hkl. (Report, p. 116, PL XXXVIIL). North Atlantic.

60. Sphenoides perforata, Hkl. (compare Bassia perforata, Hkl.). Tropical Atlantic.

61. Sphenoides australis, Hxly. (9, p. 62, pi. iv. fig. 4). South Pacific.

Genus 16. Aglaisma, Esch. (1, p. 129).

62. Aglaisma eschscholtzii, Hxly. (9, p. 60, pi. iv. fig. 2, = Eudoxia pentagons, Ggbr., 7, Taf.

xvi. figs. 1, 2). Mediterranean.

63. Aglaisma gegcnbauri, Hkl. (Report, p. 119, PI. XL.). Tropical and Subtropical Atlantic,

Station 346.

64. Aglaisma clongata, Hxly. (9, p. 61, pi. iv. fig. 3). Tropical Pacific.

REPORT ON THE SIPHONOPHOR^E. 361

Family V. Ers^eid/E, Haeckel (95, p. 33).

Genus 17«. Erssea, Esch. (1, p. 127).

65. Erssea gaimardi, Esch. (1, Taf. xii. fig. 4). Mediterranean (?).

66. Erssea compressa, Hkl. (Report, p. 123, PI. XXXIV.). Tropical and Subtropical Atlantic,

Stations 348, &c.

67. Erssea dispar, Hkl. ( = Eudoxia bojani, Esch., 1, p. 125, Taf. xii. fig. 1). Tropical Pacific (?).

Genus 17&. Lilsea, Hkl. (Report, p. 124).

68. LUxa medusina, Hkl. (Morph. Siphon.). Indian Ocean.

Family VI. Monophyim, Claus (70, p. 29).
Subfamily 1. Sph^konectid^, Huxley (9, p. 50).

Genus 18. Monophyes, Claus (70, p. 29).

69. Morwphyes princeps, Hkl. (Report, p. 129, PI. XXVII. figs. 13, 14). Indian Ocean.

70. Monophyes hydrorrhea, Hkl. ( = Sphseroncctcs hydrorrhoa, Hkl, 95, p. 34). Tropical

Atlantic (?).

71. Monophyes diptera, Hkl. ( = Monophyes gracilis, larva, Chun, 87, Taf. ii. fig. 5). Mediterranean (?).

72. Monophyes irregularis, Claus (70, p. 29, Taf. iv. figs. 16—18). Mediterranean.

Genus 19. Sphseronectes, Huxley (9, p. 50).

73. Sphseronectes kollikeri, Hxly. (9, p. 50, pi. hi. fig. 4). Indian Ocean and Tropical Pacific.

74. Sphmronectes gracilis, Hkl. ( = Monophyes gracilis, Claus, 70, p. 29, Taf. iv. figs. 8-14; Chun,

87, Taf. ii. figs. 1, 2). Mediterranean.

Genus 20. Mitrophyes, Hkl. (95, p. 34).

75. Mitrophyes peltif era, Hkl. (Report, p. 131, PI. XXVIIL). Tropical and North Atlantic, Station

352.

Subfamily 2. Cymbonectid^e, Hkl. (95, p. 34).

Genus 21. Cymbonectes, Hkl. (95, p. 34).

76. Cymbonectes huxleyi, Hkl. (Report, p. 134, PI. XXVII. figs. 1-12). Indian Ocean.

77. Cymbonectes mitra, Hkl. { = Diphyes mitra, Huxley, 9, p. 36, pl. i. fig. 4). Indian Ocean.

78. Cymbonectes cymba, Hkl. (Morph. Siphon.). Tropical Atlantic (?).

(zool. CHALL. EXP. — PART LXXVII. — 1888.) Hhlih 46

362 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 22. Muggisea, Busch (67, p. 48).

79. Muggisea kochii, Chun (86, Taf. xvii. fig. 2). Mediterranean.

80. Muggiasa pyramidalis, Busch (67, p. 48). North Atlantic (?).

81. Muggisea chamissonis, Hkl. ( = Diphyes chamissonis, Hxly., 9, p. 36, pi. i. fig. 3). Tropical

Pacific.

Genus 23. Cymba, Esch. (1, p. 133).

82. Cymba enneagonum, Esch. ( = Enneagonum hyalinum, Quoy et Gaim., 2, pi. v. figs. 1—6).

Mediterranean.

83. Cyniba erystallns, Hkl. (Report, p. 138, Pis. XLL, XLIL). Tropical Atlantic, Station 348.

84. Cymba vogtii, Hkl. ( = Abyla vogtii, Hxly., 9, p. 46, pi. ii. fig. 3). Tropical Pacific.

85. Cymba naeella, Hkl. (Morph. Siphon.). Indian Ocean.

Family VII. Diphyi dje, Esch. (1, p. 122).

Subfamily 1. Prayidje, Kolliker (4, p. 33).
Genus 24. Praya, Blainv. (24, p. 137).

86. Praya maxima, Ggbr. (7, p. 301, Taf. xvii. figs. 1-6). Mediterranean.

87. Praya cymbiformis, Chiaje (18 ; Leuck., 5 and 8). Mediterranean, North Atlantic.

88. Praya galea, Hkl. (Report, p. 146, Pis. XXXI, XXXII. ). Tropical Atlantic, Station 352.

Genus 25. Lilyopsis, Chun (87, p. 18).

89. Lilyopsis diphyes, Chun (87, = Praya diphyes, Vogt, 6, pis. xvi., xvii.; Kolliker, 4, Taf. ix.).

Mediterranean.

90. Lilyopsis medusa, Chun (87, = Praya medusa, Metschnikoff, iu an inaccessible Russian paper).

Mediterranean.

91. Lilyopsis rosea, Chun (87, Taf. ii. figs. 12, 13). Mediterranean.

92. Lilyopsis catena, Hkl. (Report, p. 150). North Atlantic.

Subfamily 2. Diphyopsid^e, Hkl. (Report, p. 145).
Genus 26. Galeolaria, Blainv. (24, p. 139).

93. Galeolaria aurantiaca, Vogt, (6, p. 110, pis. xviii, xix.; = Sulculeolaria quadrivalvis, Blainv, 24.

p. 138; =Ej)ibulia aurantiaca, Vogt, 6, p. 110). Mediterranean.

94. Galeolaria turgida, Hkl. ( — Diphyes turgida, Ggbr, 68, p. 442, Taf. xxiii.). Mediterranean.

95. Galeolaria biloba, Blainv. (Sars, 27, Heft i. p. 41, Taf. vii. figs. 16-21). North Atlantic.

REPORT ON THE SIPHONOPHOR^E. 363

96. Galeolaria truncata, Hxly. (9, p. 38; =-Dyahyes truncata, Sars, 27, Heft i. Taf. vii figs. 1-15).

North Atlantic.

97. Galeolaria sarsii, Hkl. ( = Diphyes sarsii, Ggbr., 10, p. 30, Taf. xxx. figs. 30, 31). Arctic.

98. Galeolaria australis, Blainv. (24, p. 139 ; Huxley, 9, p. 38, pi. iii. fig. 5). Indian Ocean.

99. Galeolaria stejihaimnna, Hkl. ( = Diphyes stephanomia, Mert., 25, p. 32). Tropical Pacific.

Genus 27. Diphyes, Cuvier (91, p. 61).

100. Diphyes acuminata, Leuck. (5, Taf. iii. figs. 11-19, and 8, Taf. xi. figs. 11-13). Mediterranean.

101. Diphyes sieboldii, K6TL (4, p. 36, Taf. xi.). Mediterranean.

102. Diphyes subtUis, Chun (88, p. 081). Mediterranean.

• 103. Diphyes elongata, Hyndman (64, p. 166). North Atlantic (?).

104. Diphyes appendiculata, Esch. (1, Taf. xii. fig. 7). Pacific Ocean.

105. Diphyes gracilis, Hkl. (Morph. Siphon.). Indian Ocean.

Genus 28. Diphyopsis, Hkl. (95, p. 35).

«

106. Diphyopsis campanulifera, Hkl. { = Diphyes campanulifera, Quoy et Gaim., 20, pi. i. fig. 7;

1, p. 137). Mediterranean.

107. Diphyopsis compressa, Hkl. (Report, p. 153, Pis. XXXIIL, XXXIV.). Tropical Atlantic,

Stations 327, &c.

108. Diphyopisis dispar, Hkl. (-^Diphyes dispar, Chamisso, 16, Tab. xxxiii. fig. 4). Tropical Pacific.

109. Diphyopsis angustata, Hkl. (=Diphyes angustata, Esch., 1, p. 136, Taf. xii. fig. 6). Tropical

Pacific (?).

Subfamily 3. Akylimj, L. Agassiz (36, p. 372).
Genus 29. Abyla, Quoy et Gairn. (20, p. 11).

110. Abyla trigona, Quoy et Gaim. (2, pi. iv. figs. 11—17; best figure and description by Gegenbaur,

10, Taf. xxvii., xxviii.). Mediterranean.

111. Abyla carina, Hkl. (Report, p. 156, Pis. XXXV., XXXVL). Tropical Atlantic, Station 348.

112. Abyla alata, Hkl. ( — Abyla trigona, Hxly., 9, pi. iii. fig. 1). Indian and Tropical Pacific.

113. Abyla leuckarti, Hxly. (9, p. 49, pi. iii. fig. 2). South Pacific.

Genus 30. Bassia, Quoy et Gaim. (3, p. 451).

114. Bassia tetragonal, Hkl. (Morph. Siphon.). Indian Ocean.

115. Bassia obeliscus, Hkl. (Report, p. 160, Pis. XXXVIL, XXXVIII.). North Atlantic, Station 354.

116. Bassia perforata, L. Agassiz. (36, p. 372; —Abyla perforata, Ggbr., 10, Taf. xxx. figs. 20, 21).

Tropical Atlantic.

117. Bassia quadrilatera, Quoy et Gaim. (3, p. 451; = Abyla bassensis, Hxly., 9, p. 45, pi. ii.

fig. 1). South Pacific.

364 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 31. Calpe, Quoy et Gaim. (20, p. 11).

118. Calpe pcntagona, Quoy et Gaim. (20, p. 11, pi. \\.A. figs. 1-7; =Abyla pcntagona, Esch.).

Accurate description and figures by Kolliker (4, Taf. x.) ; Leuckart (5, Taf. iii. figs. 1-10 ;
8, Taf. xi. figs. 1-10) ; Gegenbaur (10, Taf. xxLx.). Mediterranean.

119. Calpe gcgenbauri, Hkl. (Report, p. 164, Pis. XXXIX., XL.). Tropical and Southern Atlantic,

Stations 338, 346.

120. Calpe huxleyi, Hkl. ( = Abyla pcntagona, Hxly., 9, p. 40, pi. ii. fig. 2). Tropical Pacific.

Family VIII. Desmophyid*, Hkl. (95, p. 36).
Genus 32a. Dcsmalia, Hkl. (Report, p. 168).

121. Dcsmalia imbricata, Hkl. (Report, p. 169). Indian Ocean.

Genus 32&. Dcsmop>hycs, Hkl. (95, p. 36).

122. Desmophyes annectcns, Hkl. (Report, p. 170, PI. XXX.). Indian Ocean.

Family IX. Polyphyid*, Chun (86, p. ] 2 ).

Subfamily 1. Hippopodid^e, Koll. (4, p. 28).

Genus 33. Hippopodius, Quoy et Gaim. (20, torn. x.).

123. Hippopodius gleba, Leuck. (8, p. 299, Taf. xii. figs. 1^1). Mediterranean

124. Hippopodius squamatus, Hkl (Morph. Siphon.). South Atlantic (?).

125. Hippopodius cupola, Hkl. (Morph. Siphon.). Pacific.

Genus 34. Polyphyes, Hkl. (95, p. 36).

126. Polyphyes elcphantopus, Hkl. ( = Hippopodius neapolitanus, Koll., 4, p. 28, Taf. vi. figs. 1-5;

= Elcphantopus neapolitanus, Lesson, 3, p. 473). Mediterranean.

127. Polyphyes ungnlata, Hkl. (Report, p. 179, PI. XXIX. figs. 1-8). Tropical Atlantic, Station 352.

Subfamily 2. Vogtid^e, Hkl. (Report, pp. 177, 182).
Genus 35. Vogtia, Koll. (4, p. 31).

128. Vogtia pentacantha, Koll. (4, p. 31, Taf. viii). Mediterranean.

129. Vogtia spinosa, Kef. und Eld. (33, p. 24, Taf. v. figs. 16, 17). Tropical Atlantic.

130. Vogtia kollikeri, Hkl. (Report, p. 182, PI. XXIX figs. 9-14). South Atlantic, Station 326.

REPORT ON THE SIPHONOPHOR^. 365

Order III. PHYSONECT^E, Haeckel (95, p. 38).
Family X. Cikcalid ,e, Hkl. (95, p. 38).

Genus 36. Circalia, Hkl. (95, p. 38).

131. Circalia stcphanoma, Hkl. (Report, p. 198, PI. XXI. figs. 1-4). North Atlantic.

132. Circalia haphrhiza, Hkl. ( = Physophora alba, Quoy et Gaim., 2, pi. i. figs. 1—9; = Haplorhiza

alba, L. Agassiz, 36, p. 368). South Atlantic.

133. Circalia papillosa, Hkl. (=Ayalma papillosum, Fewk., 44, pi. v. figs. 5, 6). Tropical Atlantic ( ' ).

Family XL Athoeid*, Hkl. (95, p. 38).

Genus 37. Athoria, Hkl. (95, p. 39).

134. AtJwria larvalis, Hkl. (Report, p. 202, PI. XXI. figs. 5-8). Indian Ocean.

135. AtJwria bractealis, Hkl. (Report, p. 201). South Pacific, Station 288 (?).

Genus 38. Athoralia, Hkl. (95, p. 39).

136. Athoralia coronula, Hkl. (Morph. Siphon.). Indian Ocean.

Family XII. Apolemid .e, Hxly. (9, p. 70).

Genus 39. Dicymba, Hkl. (95, p. 39).

137. Dicymba diphyopsis, Hkl. (Report, p. 210, PI. XVIII. figs. 1-7). Indian Ocean.

Genus 40a. Apolemia, Esch. (1, p. 143).

138. Apolemia uvaria, Esch. (4, Taf. vi. figs. 6-9; 7, p. 319, Taf. xviii. figs. 1-4; 8, Taf. xii. figs.

8—11, &c). Mediterranean.

Genus 40&. Apolemopsis, Brandt (25, p. 36).

139. Apolemopsis uviformis, Hkl. ( = Stephanomia uviformis, Lesueur, in an unpublished plate, and

15; = Apolemia lesucuria, Lesson, 3, p. 518). North Atlantic.

140. Apolemopsis dubia, Brdt. (25, p. 36). Tropical Pacific.

;366 THE VOYAGE OF H.M.S. CHALLENGER.

Family XIII. Agalmid^e, Brandt (25, p. 34).

Subfamily 1. Crystallodin^;, Hkl. (95, p. 39).

Genus 41. Stephanomia, Peron et Lesueur (14).

141. Stephanomia amphitrites, Peron et Lesueur (14, pi. xxix. fig. 5 ; 9, p. 72, pi. vi.). Tropical

Pacific.

142. Stephanomia nereidum, Hkl. (Morph. Siphon.). Indian Ocean.

Genus 42. Crystallodes, Hkl. (84, p. 43).

143. Crystallodes rigida, Hkl. (84, p. 43, Taf. vi.-xiii). North Atlantic.

144. Crystallodes vitrea, Hkl. (Report, p. 222, PI. XVIL). Indian Ocean.

145. Crystallodes mertensii, Hkl. {= Agalma mertensii, Brandt, 25, p. 34, figured by Mertens). North

Pacific.

146. Crystallodes pletlwsoma, Hkl. {-=Plethosoma crystalloides, Less., 22, pi. iv. fig. 2). Tropical

Pacific.

Genus 43. Phyllophysa, L. Agassiz (36, p. 369).

147. Phyllophysa squamacea, Hkl. (Morph. Siphon.). (= Stephanomia amphitrites, Hxly., 9, pi. vi.).

South Pacific (?).

148. Phyllophysa foliacea, L. Agassiz ( = Stephanomia foliacea, Quoy et Gaim., 2, pi. iii. figs. 8-12).

Tropical Pacific (?).

Genus 44. Agalma, Esch. (21, p. 743 ; 1, p. 150).

149. Agalma okenii, Esch. (1, Taf. xiii. fig. 1 ; 21, Taf. v. fig. 17). North Pacific.

150. Agalma breve, Hxly. (9, p. 75, pi. vii). South Pacific.

151. Agalma eschscholtzii, Hkl. (Report, p. 226, Pi. XVIII. figs. 8-17). Indian Ocean.

152. Agalma polygonata, Hkl. ( = Crystallomia polygonata, Dana, 73, p. 459). North Pacific (?).

153. Agalma clavata, Leack. (8, Taf. xiii. figs. 1-6). Mediterranean.

Subfamily 2. Anthemodin^e, Hkl. (95, p. 40).

Genus 45. Anthemodes, Hkl. (38, p. 36).

154. Anthemodes ordinata, Hkl. (Report, p. 229, Pis. XIV., XV.). North Atlantic.

155. Anthemodes articulata, Hkl. (Morph. Siphon.). South Atlantic, Station 325.

EEPOET ON THE SIPHONOPHOEjE. 367

Genus 46. Cuneolaria, Eysenhardt (16, p. 309).

156. Cuneolaria incisa, Eysenhardt (16, p. 369, pi. xxxiii. fig. 5). North Pacific (?).

157. Cuneolaria imbricata, L. Agassiz ( = Stephanomia imbricata, Quoy et Gaini., 2, pi. iii.

figs. 13-15). South Pacific (?).

Genus 47. Halistemma, Hxly. (9, p. 129).

158. Halistemma rubrum, Hxly. (=Agalma rubra, Vogt, 6, pis. vii.-xi.). Mediterranean.

159. Halistemma. punctatum, L. Agassiz (36, p. 369; = Agalmopsis punctata, Koll., 4, Taf. i\\).

South Mediterranean (?).

Genus 48a. Cupulita, Quoy et Gaini. (19, p. 580).

160. Cupulita bowdichii, Quoy et Gaim. (19, pi. lxxxvii. figs. 14-16). South Pacific (?).

161. Cupulita sarsii, Hkl. (= Agalmopsis elegans, Sars, partim, 27, Heft i. Taf. v., not vi.). North

Atlantic.

162. Cupulita canariensis, Hkl. ( = Anthcmodes canariensis, Hkl., 38, p. 36, Taf. i.). North-east

Atlantic.

163. Cupulita cara, Hkl. ( = Nanomia cara, A. Agassiz, 37, p. 200). North-west Atlantic.

164. Cupulita fragilis, Hkl. ( = Agalmopsis fragilis, Fewk., 44, pi. v. fig. 2, pi. vi). Tropical

Atlantic,

165. Cupulita- pirta, Hkl. ( = Halistemma pictwn, Metschn., 1871, in an inaccessible Russian paper,

Tab. ii.). Mediterranean.

166. Cupulita tergestina, Hkl. ( = Halistemma tcrgestinum, Claus, 74, Taf. i.-v.). Adriatic.

Genus 486. Agalmopsis, Sars (27, Heft i. p. 32).

167. Agalmopsis elegans, Sars, partim (27, Heft i. Taf. vi., not v.). North Atlantic.

168. Agalmopsis catena, Hkl. ( = Agalma elegans, Fewk., 43, p. 163, pis. ix., x.). Ontogeny, 89,

p. 239, pis. i.-iv. Tropical Atlantic.

169. Agalmopsis dissoluta, Hkl. (Morph. Siphon.). South Atlantic.

170. Agalmopsis sarsii, Koll. (4, p. 10, Taf. hi.). Mediterranean.

Genus 49. Lychnagalma, Hkl. (95, p. 40).

171. Lychnagalma vesicularia, Hkl. (Eeport, p. 235, PI. XVI.). Indian Ocean.

172. Lychnagalma utricularia, Hkl. (= Agalmopsis utricularia, Claus, 75; = Calliagalma utricularia,

Fewk., 42, vol. xvii. p. 844). Mediterranean.

368 THE VOYAGE OF H.M.S. CHALLENGER.

Family XIV. Fors k alid^e, Hkl. (95, p. 42),
Genus 50. Strobalia, Hkl. (95, p. 42).

173. Strobalia cupola, Hkl. (Morph. Siphon.). Indian Ocean.

174. Strobalia conifera, Hkl. (Report, p. 243). South Pacific, Station 288.

Genus 51. ForsJcalia, Koll. (4, p. 2).

175. ForsJcalia contorta, Leuck. ( = StcpJianomia, Milne-Edwards, 71, pis. vii.-x.). Mediterranean.

176. Forskalia edwardsii, Koll. (4, p. 2, Taf. L, ii). Mediterranean.

177. Forskalia tholoides, Hkl. (Report, p. 244, Pis. VIII.-X.). North Atlantic.

178. ForsJcalia atlantica, Hkl. ( = StcpJianomia atlantica, Fewk., 44, pi. v. fig. 1). Tropical Atlantic.

Genus 52. ForsJcaliopsis, Hkl. (Report, p. 247).

179. ForsJcaliopsis opJiiura, Hkl. (—ForsJcalia opJiiura, Leuck., 8, p. 351, Taf. xiii. figs. 18-21).

Mediterranean.
180.- ForsJcaliopsis magnifica, Hkl. (Report, p. 248). Indian Ocean.

Genus 53. BatJiypJiysa, Studer (40, p. 21).

■

181. BatJiypJiysa abyssoruni, Studer (40, p. 21, Taf. iii). North Atlantic.

182. BatJiypJiysa grandis, Hkl. ( = Pteropliysa grandis, Fewk., 45, p. 969). North Atlantic (?)■

183. BatJiypJiysa gigantea, Hkl. (Morph. Siphon.). South Atlantic, Station 323 (?).

Family XV. N e c t a l I d,e, Hkl. (95, p. 41).

Genus. 54«. Nectalia, Hkl. (95, p. 41).

184. Ncclalia loligo, Hkl. (Report, p. 252, PI. XIIL). North Atlantic.

Genus 546. Sphyrophysd, L. Agassiz (36, p. 368).

185. SpJiyropJiysa intermedia, L. Agassiz ( = PJiysopJiora intermedia, Quoy et Gaim., 2, pi. i. figs. 10-18).

Tropical Atlantic (?).

Family XVI. Lisgolabid/E, Hkl. (95, p. 41).

Genus 55. PJiysopJiora, Forskal (11, p. 119).

186. PJiysopJiora Jiydrostatica, Forskal (11, p. 119; Glaus, 34, Taf. xxv.-xxvii.). North Mediterranean.

187. PJiysopJiora pJiilippii, Koll. (4, p. 19, Taf. v.). South Mediterranean.

188. PJiysopJiora mctgnifica, Hkl. (84, p. 36, Taf. i.-v.). North Atlantic.

REPORT ON THE SIPHONOPHOR^E. 369

189. Physophora lorcalis, Sars (27, Heft iii. Taf. v., vi.). North Atlantic.

190. Physopkora disticha, Lesson (22, pi. xvi. fig. 3). Tropical Pacific (?).

191. Physophora myzonema, Peron et Les. (14, pi. xxix. fig. 4). Tropical Atlantic (?).

Genus 56. Discolabe, Esch. (1, p. 155).

192. Discolabe mediterranea, Esch. ( = Physophora tetrasticha, Phil., 72, Taf. v.). Mediterranean.

193. Discolabe tetrasticha, Hkl. (Morph. Siphon.). North Atlantic (?).

194. Discolabe quadriyata, Hkl. (Report, p. 263, Pis. XIX., XX.). Indian Ocean.

Genus 57. Stcphanospira, Ggbr. (10, p. 67).

195. Stephanospira insiynis, Ggbr. (10, p. 67, figs. 53-56). Tropical Atlantic (?).

196. Stephanospira corona, Hkl. (Morph. Siphon.). North Atlantic.

Family XVII. Anthophysid^e, Brandt (25, p. 35).
(Athorybidw, Huxley, 9, pp. 71, 85).

Genus 58. Ehodophysa, Blainv. (24, p. 123).

197. Ehodophysa corona, Hkl. (Report, p. 274). Indian Ocean.

Genus 59. Melophysa, Hkl. (95, p. 42).

198. Melophysa nulo, Hkl. ( = Athorybia melol, Quoy, 2, pi. ii. figs. 7-12). Mediterranean (?).

Genus 60. Athorybia, Esch. (1, p. 153).

199. Athorybia rosacea, Esch. (4, p. 24, Taf. vii.). Mediterranean.

200. Athorybia hcliantha, Ggbr. (10, Taf. xxxi. figs. 43, 44). North Atlantic.

201. Athorybia ocellata, Hkl. (Report, p. 276, Pis. XL, XII. figs. 10-18). North Atlantic.

202. Athorybia indica, Hkl. ( = Athorybia rosacea, Hxly., 9, p. 86, pi. ix.). Indian Ocean.

Genus 61. Anthophysa, Mertens (25, p. 35).

203. Anthophysa rosea, Mertens (25, p. 35). North Pacific.

204. Anthophysa formosa, Hkl. (= Athorybia formosa, Fewk., 44, pi. v. figs. 3,4). North Atlantic.

205. Anthophysa darwinii, Hkl. (Report, p. 278, PI. XII. figs. 7-9). South Atlantic, Station 334.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) Hhhh 47

370 THE VOYAGE OF H.M.S. CHALLENGER.

Order IV. AURONECTiE, Haeckel (95, p. 43).

Family XVIII. Stephalid/E, Hkl. (95, p. 43).

Genus 62a. Stcphalia, Hkl. (95, p. 43).

206. Stcphalia corona, Hkl. (Report, p. 297, PL VII.). North Atlantic ("Triton" Expedition).

Genus 62&. Stephonalia, Hkl. (Report, p. 299).

207. Stephonalia bathyphysa, HkL (Report, p. 299, PL VI.). South Pacific, Station 166.

Family XIX. Khodalid*, Hkl. (95, p. 43).
Genus 63. Auralia, Hkl. (95, p. 43).

208. Auralia profunda, Hkl. (Report, p. 301). Tropical Atlantic.

209. Auralia globosa, Hkl. (= Angclopsis globosa, Fewk., 45, p. 972, pi. x. figs. 4, 5). Tropical

Atlantic (?).

Genus 64. Rhodalia, Hkl. (95, p. 43).

210. Rhodalia miranda, Hkl. (Report, p. 302, Pis. I.-V.). South Atlantic, Station 320.

Order V. CYSTONECTiE, Haeckel (95, p. 44).

Family XX. Cystalid*, Hkl. (95, p. 44).

Genus 65. Cystalia, Hkl. (95, p. 44).

211. Cystalia monogastrica, Hkl. (Report, p. 316, PL XXII. figs. 1-5). Indian Ocean; South

Pacific, Station 288.

212. Cijstalia challengeri, Hkl. (Report, p. 314). South Pacific, Station 288 (?).

Family XXI. Rhizophysid/E, Bdt. (25, p. 33).
Subfamily 1. Cannophysid.*:, Hkl. (95, p. 44).
Genus 66. Aurophysa, Hkl. (95, p. 44).

213. Aurophysa ordinata, Hkl. (Morph. Siphon.). Indian Ocean.

214. Aurophysa inermis, Hkl. {—Rhizophysa inermis, Studer, 40, p. 13, Taf. i. figs. 3, 8, 9, 10).

Indian Ocean.

REPORT ON THE SIPHONOPHOR^E. 371

Genus 67. Cannophysa, Hkl. (95, p. 44).

215. Cannophysa murrayana, Hkl. (Report, p. 324, PL XXIV.). North Atlantic.

216. Cannophysa gracilis, Hkl. ( = Rhizophysa gracilis, Fewk., 44, p. 269, pi. vi. figs. 1-6). Tropical

Atlantic.

Subfamily 2. Linophysiile, Hkl. (95, p. 45).

Genus 68. Linophysa, Hkl. (95, p. 45).

217. Linophysa coni/era, Hkl. ( = Rhizophysa conifera, Studer, 40, p. 4, Taf. i.). Tropical Atlantic.

Genus 69. Nectophysa, HkL (95, p. 45).

218. Nectophysa vryvilhi, Hkl. (Report, p. 327, PL XXIII. ). North Atlantic.

219. Nectophysa eyscnhardtii, Hkl. { = Rhizophysa eyscnhardtii, Ggbr., 10, p. 78, Tab. xxxi. figs. 46-

49). North Atlantic

Genus 70. Pneumophysa, Hkl. (95, p. 45).

220. Pneumophysa gegenbauri, Hkl. (Morph. Siphon.). Indian Ocean.

Genus 71. Rhizophysa, Peron et Lesueur (14).

221. Rhizophysa filiformis, Laink. ( = Physophora filifonnis, Forsk. ; Ggbr., 7, p. 324, Taf. xviii. figs.

5—11). Mediterranean.

222. Rhizophysa planostoma, Peron (14, pi. xxix. fig. 3). Tropical Atlantic.

223. Rhizophysa mertensii, Lesson (3, p. 492 ; — Epibulia mertensii, Brdt., 25, p. 33). North Pacific.

Family XXII. Salacid^e, HkL (95, p. 45).

Genus 72. Salacia, Hkl. (95, p. 45).

224. Salacia polygastrica, Hkl. (Report, p. 331, PL XXV.). Tropical Atlantic, Station 338.

225. Salacia uvaria, HkL ( = Rhizophysa uvaria, Fewk., 45, p. 967, pi. x. fig. 6). North Atlantic.

Family XXIII. Epibulid^e, Hkl. (Report, p. 332).

Genus 73a. Epibulia, Eschscholtz (1, p. 148; =Arethusa, Hkl., 95, p. 46).

226. Epibulia ritteriana, Hkl. (Report, p. 335, PL XXII. figs. 6-8). Indian Ocean.

227. Epibulia chamissonis, Esch. (= Rhizophysa chamissonis, Eysenhardt, 77, Tab. xxxv. fig. 3).

North Pacific.

228. Epibulia crythrophysa, Brdt. (25, p. 34), figured by Mortens. Tropical Pacific.

372 THE VOYAGE OF H.M.S. CHALLENGER.

Genus 736. Angela, Lesson (3, p. 496).

229. Angela cytherea, Less. (3, p. 496, pi. ix. fig. 1). Tropical Atlantic (?).

Family XXIV. PhysalidjE, Brdt. (25, p. 36).

Subfamily 1. Arethusid/E, Hkl. (Report, p. 347).

Genus 74«. Aloplwta, Brdt. (25, p. 37).

230. Alophota giltschiana, Hkl. (Report, p. 348, PI. XXVI. figs. 1-3). North Atlantic.

231. Alophota olfersii, Brdt. (25, p. 37). Tropical Atlantic.

232. Alophota mertensii, Hkl. (Morph. Siphon.). Indian Ocean.

Genus 746. Arethusa, Hkl. (Report, p. 349).

233. Arethusa challenged., Hkl. (Report, p. 349, PI. XXVI. figs. 4-8). North Atlantic, Station 354.

234. Arethusa thalia, Hkl. (Morph. Siphon.). Indian Ocean (?).

Subfamily 2. CauavelliDjE, Hkl. (Report, p. 347).
Genus 75a. Physalia, Lamk. (90, torn. ii. p. 480).

235. Physalia pelagica, Bosc (Eyshdt., 77, p. 45, Tab. xxxv. fig. 2). South Atlantic.

236. Physalia comuta, Til. (76, p. 42, Tab. i. figs. 15, 16). Indian Ocean (?).

237. Physalia utriculus, Esch. (1, p. 163, Taf. xiv. figs. 2, 3). Tropical and Subtropical Pacific.

238. Physalia megalista, Lamk. (Peron, 14, pi. xxix. fig. 1), Mertens (?). South Atlantic and Indian

Ocean.

Genus 756. Caravclla, Hkl. (Report, p. 351).

239. Garavella gigantca, Hkl. ( = Physalia cystisoma, Lesson, partim ; —Physalia gigantca, Bory ;

Postels et Mertens, Icon.). Tropical and Southern Atlantic.

240. Caravella maxima, Hkl. (= Physalia caravclla, Esch., 1, Taf. xiv. fig. 1; = Physalia arethusa,

Olfers, 79, Taf. i., ii.; L. Agassiz, 36, pi. xxxv.). Tropical and Northern Atlantic.

GLOSSARY.

N.B. — The signification of the characters is the same in all the Plates.

Latin Scientific Term.

English Term.

German Term.

a

Truncus (Ccenosarc).

Common stem.

Stamm.

aa

Apex trunci.

Top of the stem.

Scheitelpunkt.

ab

Cormidia.

Groups of persons.

Personen-Gruppen.

ac

Canales trunci.

Vessels of the trunk.

Stamm-Canale.

ad

Linea dorsalis trunci.

Dorsal line of the stem.

Stamm-Eiickenlinie.

of

Facetta (insertio cormidii).

Insertion of the cormidia.

Cormidien-Facetten.

ah

Antrum hypocystale

Hypocystic cavity.

Blasengrund-Hohle.

ai

Internodia trunci.

Internodes of the trunk.

Stamm-Zwischenknoten.

am

Nodi trunci.

Nodes of the trunk.

Stamm-Knoten.

an

Nectosonia (truncus motorius).

Swimming body.

Schwimmkorper.

ao

Ostium terminale (prostoma).

Primitive mouth.

TJrmund.

ap

Sipho primordialis (truncus).

Primitive siphon.

Ursipho.

as

Siphosoma (truncus nutritivus)

. Nutritive body.

Nahrkorper.

at

Tubus trunci centralis.

Axial tube of the stem.

Axenrohr.

av

Linea ventralis trunci.

Ventral line of the stem.

Stamm-Bauchlinie.

az

Fulcrum trunci.

Supporting plate of the stem.

Stamm-Stiitzplatte.

h

Braetex {Hydrophyllid).

Protectives.

Deckstiich .

ba

Facies exumbralis bractese.

Exumbrellar face of the bract.

Deckstiick-Mantel.

bb

Basis braeteEe.

Base of the bract.

Deckstiick-Basis.

be

Phyllocystis.

Pbyllocyst.

Deckstuck-Blase.

bd

Margo dorsalis.

Dorsal edge of the bract.

Bucken-Kante.

bh

Cavitus bractealis.

Subumbrellar cavity of the bract.

Deckstuck-Hohle.

bk

Cnidotsenise.

XJrticating bands.

Nesselrippen.

bl-

Margo sinister.

Left-hand edge.

Linke Kante.

ip

Pedunculus bractea?.

Pedicle of the bract.

Deckstiick-StieL

hv

Margo ventralis.

Ventral edge of the bract.

Bauch-Kante.

bx

Margo dexter.

Eight-hand edge.

Eechte Kante.

c

Candles (vasa nutritioa).

Vessels.

Candle.

ca

Canalis axialis.

Axial vessel.

Axen-Canal.

cb

Canalis bractealis

Canal of the bract.

Deckstiick-CanaL

374

THE VOYAGE OF H.M.S. CHALLENGER.

Latin Scientific Term.

cc Canalis eircularis.

cd Canalis dorsalis.

ce Canales palliales.

cf Canalis ovarii.

eg Canalis gonophorae.

eh Canalis spermarii.

ci Canalis gemmalis.

ek Canales centradeniae.

el Canalis sinister.

cm Canales liepatici.

en Canalis nectophorae.

co Canalis oleophorus.

cp Canalis pedunculi

cq Canalis palponis.

cr Canales radiales.

cs Canalis somatocystis.

ct Canalis tentaculi.

cu Canales umbrellse.

cv Canalis ventralis.

no Canales renales.

ex Canalis dexter.

cy Canales spadicini.

cz Canalis coronalis (in sulco coro-
nali Disconectarum).

d Entoderma.

e Exoderma.

English Term.

Annular marginal vessel.

Dorsal radial vessel.

Mantle-vessels.

Ovarial vessel.

Gonophoral vessel.

Testicular vessel.

Bud vessel.

Vessels of the central gland.

Lefthand radial vessel.

Liver-vessels.

Nectocalycine duct.

Oleocyst.

Pedicular vessel.

Hydrocystic vessel.

Radial vessels.

Acrocyst or somatocyst.

Tentacular vessel.

Vessels of the umbrella.

Ventral radial vessel.

Kidney-vessels.

Right-hand radial vessel.

Spadicine vessels.

Coronal vessel of the subumbrella.

Entoderm.

Exoderm.

f Gynophorx (Gonophorx Female Medusx.

femininx).

fc Canalis centralis gynophorae. Canal of the ovisac.

fm Ovarium (manubrium medusae). Ovisac.

fo Acini ovulorum. Egg-clusters.

fp Pedunculus gynophorae. Pedicle of the gynophore.

fu Umbrella gynophorae. Gynocalyx.

fx Spadix feminina. Gynospadix.

g Gonophoree (Medusx Sexuales).

ga Gonodendron (gonocormus).

gb Cormidia sexual ia.

gc Canalis centralis gonophorae.

gf Gonodendron femininum.

gh Gonodendron masculinum.

gk Cnidonodes of the gonophorus.

gm Manubrium (gonades).

gp Pedunculus gonophorae.

gq Gonopalpon (palpo sexualis).

gs Gonostylus(truncusgonodendri),

Sexual Medusx.

Sexual cluster.

Branches of the sexual cluster.

Central canal of the gonophore.

Female cluster.

Male cluster.

Urticating nodes of the sexual

Medusae.
Gonosac.

Pedicle of the gonophore.
Sexual taster.
Stem of the sexual cluster.

German Term.

Ring-Canal (am Schirmrande).

Riicken-Canal.

Mantel-Canale.

Eierstocks-Canal.

Sexual-Canal.

Hoden-Canal.

Knospen-Canal.

Caniile der Centraldriise.

Linker Radial-Canal.

Leber-Canale.

Schwimmglocken-Canal.

Olblase.

Stiel-Canal.

Taster-Canal.

Radial Caniile.

Saftbehalter.

Tentakel-Canal.

Schirm-Canale.

Bauch-Canal.

Nieren-Canale.

Rechter Radial-Canal.

Spadicin-Canale.

Kranz-Canal.

Darmblatt.
Hautblatt.
Weibchen.

Eierstocks-Canal.

Eierstock.

Eier-Trauben.

Weibchen-Stiel.

Eierstocks-Schirm.

Eierstocks-Spadix.

Geschlech ts-Personen.

Geschlechts-Traube.
Geschlechts-Trauben-Aeste.
Canal der Geschlechts-Person.
Weibliche Traube.
Mannliche Traube.
Nesselknoten der Geschlechts-

Personen.
Gesclilechts-Driise.
Stiel der Geschlecht-Person.
Geschlechts-Taster.
Stamm der Geschlechts-Traube.

REPORT ON THE SIPHONOPHOIl^E.

375

Latin Scientific Term.

gu Gonumbrella.
gx Spadix.

h Androphorae {Gonophoraz
masculinx).

English Term.

Umbrella of the gonophore.
Axial tube of the manubrium.

Male Medusx.

I Aurophora (Campana pneu-
matica).

la Auroductus (eanalis axialis).

lb Basis aurophora?.

Ic Canal circularis aurophorae.

le Epithelium auroductus.

If Vagina pistilli (eutieularis).

li Auropyle (ostium internum).

Im Museulus pistilli.

In Nuclei musculorum.

lo Aurostigma (ostium externum).

lp Pistillum.

Ir Bursas radiales aurophorae.

Is Septa radialia.

h Fulcrum aurophora?.

German Term.

Schirm der Geschlechts-Person.
Entoderm-Rohr der Geschlechts-
Driise.

Mannchen.

he

Canalis centralis androphorae.

Canal of the sperm-sac.

Hoden-Canal.

hm

Spermarium (manubrium
Medusae masculinae).

Sperm-sac.

Hoden.

hp

Pedunculus androphorae.

Pedicle of the androphore.

Mannchen-Stiel.

hs

Sperma.

Sperm.

Samen.

hu

Umbrella androphorae.

Androcalyx.

Hoden-Schirm.

hx

Spadix masculina.

Androspadix.

Hoden-Spadix.

i

Gemmx.

Buds.

K.7iospen.

ib

Gemma bracteas.

Bud of bract.

Deckstiick-Knospe.

i<J

Gemma gonophorae.

Bud of gonophore.

Geschlechts-Knospe.

in

Gemma nectophorse.

Bud of nectocalyx.

Schwimmglocken-Knospe.

iq

Gemma palponis.

Bud of taster.

Taster-Knospe.

is

Gemma siphonis.

Bud of polypite.

Sipho-Knospe.

it

Gemma tentaculi.

Bud of tentacle.

Tentakel-Knospe.

h

Cnidia (Nematillx).

Urticating organs.

Nessel organe.

hb

Cnidoblasti.

Thread-cells.

Nessel-Zellen.

b-

Cnidocystae (capsulae urticantes]

1. Thread-cysts.

Nessel-Kapseln.

hi

Cnidoblasti grandes.

Large thread-cells.

Grosse Nessel-Zellen.

hi

Cnidoblasti laterales.

Lateral thread-cells.

Seitliche Nessel-Zellen.

hm

Cnidoblasti mediales.

Median thread-cells.

Mittlere Nessel-Zellen.

hn

Cnidonodi.

Urticating nodes.

Nessel-Knoten.

hp

Cnidoblasti pyriformes.

Pyriform thread-cells.

BirnfOrrnige Nessel-Zellen.

hs

Cnidosacci.

Urticating sacculi.

Nessel-Sackchen.

hi

Cnidotaenia.

Urticating band.

Nessel-Band.

A ir-bell (of the Auronectae).

Auroduct.

Base of the aurophore.
Pting-canal of the aurophore.
Epithelium of the auroduct.
Sheath of the pistil.
Aperture of the auroduct.
Muscle of the pistil.
Nuclei of the muscles.
Mouth of the auroduct.
Pistil of the aurophore.
Radial pouches of the aurophore.
Radial septa (between them).
Supporting plate.

Luftgloche.

Luftgang.

Luftglocken-Grund.

Ring canal der Luftglocke.

Luftgang-Epithel.

Scheide des Luftstempels.

Luftglocken-Pforte.

Stempel-MuskeL

Muskel-Kerne.

Luftglocken-Miindung.

Luftglocken-Stempel.

Radial-Taschen der Luftglocke.

Radial-Septen.

Stutzplatte der Luftglocke.

m Musculi.

Muscles.

Musheln.

376

THE VOYAGE OF H.M.S. CHALLENGER.

Latin Scientific Term.

n Nectophorse (nectocali/ces).

na Apex nectophorse.

nb Basis pedunculi (insertio).

nc Canalis circularis nectophorse.

ml Ala dorsalis nectophorse.

ne Canales accessorii pedunculi.

nf Fissura infundibuli.

ng Margo basalis nectoplioras.

nh Cavitas nectophorse.

ni Infundibulum (hydrcecium).

nk Margo coryphalis (crista sagit-

talis).

id Ala sinistra nectophorse.

nm Musculi pedunculi.

nn Nectophora specialis (Calyco-

nectse).

an Ostium nectophorse.

tip Pedunculus nectophoras.

nq Condylus articularis nectophorse

(Abylidse).

hi- C'anales radiales nectophorse.

ns Canalis peduncularis.

itt Septum frontale nectophorae.

nu Gelatina nectophorse.

nv Ala ventralis nectophorse.

mo Nectosaccus.

7ix Ala dextra nectophorse.

nz Ala dentata nectophorse.

u Ovula.

01 Macula germinativa.

02 Vesicula germinativa.

03 Lecythus germinativus.

ji Pnemnatophora.

pa Antrum pneumaticum.

pb Basis (pedunculus) pneu-

matophorse.
pc Cavitas pericystaHs.
pd Pneumadenia (glandula pneu-

matica).
pe. Stigmata (pori exumbrales).
pf Pneumatocysta (lagena pneu-

matica).
pij Pneurnothyrse (pori communi-

cautes annulorum).
jih Camera centralis pneumato-

cystse.

English Term.

liiriiiiniiinj-hells.

Top of the swimming-bell.

Basal insertion of the bell-pedicle.

Marginal ring-canal.

Dorsal wing of the bell.

Accessory pedicular canals.

Hydroecial cleft.

Edge of the bell-base.

Bell cavity.

Hydrcecial cavity.

Sagittal crest of the nectocalyx.

Left wing of the swimming-bell.
Muscles of the pedicle.
Special nectophore.

Mouth of the nectosac.

Pedicle of the nectophore.

Articular apophysis of the necto-
calyx.

Radial canals of the bell.

Pedicular canal.

Septum between nectosac and hy-
drcecium.

Jelly of the swimming-bell.

Ventral wing of the bell.

Swimming-sac.

Right wing of the swimming-bell.

Toothed wing of the bell.

Eggs.

Nucleolus of the egg.
Nucleus of the egg.
Protoplasm of the egg.

Swimming- Bladder.

Air-cavity.

Basal pedicle of the float.

Pericystic cavity of the float.
Air-secreting gland.

Pneumatic pores (Disconectae).
Air-flask.

German Term.

Schwimmglocken.

Schwimmglocken-Scheitel.

Insertions-Basis.

Ring-canal (der Glocken-Miindung).

Riickenflugel der Schwimmglocke.

Stiel canal- Aeste.

Gehiiuse-Spalte.

Basal-Kan te.

Sch wimmglocken-Hbhle.

Gehause des Stammes.

Scheitel-Kante der Schwimmglocke.

Linker Fliigel der Schwimmglocke.
Stiel muskel.
Special-Schwimmglocke.

Schwimmholilen-Miindung.
Schwimmglocken-Stiel.
Gelenk-Kopf der Schwimmglocke.

Radial-Canale der Schwimmglocke.

Stiel-Canal.

Frontal-Septum der Schwimmglocke.

Schirm-Gallerte.

Bauchfliigel der Schwimmglocke.

Schwimmsack.

Eechter Fliigel der Schwimmglocke.

Zahnflugel der Schwimmglocke.

Eier.

Keimfleck.

Keimbliischen.

Keimdotter.

Si'luvimmblase.

Lufthbhle.
Schwimmblasen-Stiel.

Pericyst-Hohle der Schwimmblase.
Luftdriise.

Luftporen der Exumbrella.
Luftflasche.

Apertures of the ring-chambers Commuiiications-Thuren der Luft-

(Disconectse). Ring-Kammern.

Central chamber of the float. Central kammer der Luftflasche.

REPORT ON THE SIPHONOPHORyE.

Latin Scientific Term.

pi Infundibulum (pneumatochone).

pk Camera> concentricaj pneu-

matocystse.

pi Foveola auropylae.

pm Musculi longituclinale8.

pn Musculi transversi.

po Ostium apicale (stigma centrale).

pp Pigmcntum apicale (mitra ocel-

laris).

pq Bursa; radiales pneuniatopbone.

pr Septa radiaba.

p* Pneumatosaccus.

pt Tracheae.

ptt Pneumatocodon (umbrella pneu-

matica).

pv Villi hypocystales.

I'ir Tapetum endocystale.

px Apex pneumatophorse.

py Pylorus infuudibuli.

pz Fulcrum (lamina fulcralis).

q Palponvs (Hydroeystcc).

qa Apex palponis.

qb Basis palponis.

qc Cavum palponis.

qo Ocellus palponis.

qp Pedunculus palponis.

r Palpacula.

«

sa
sb
sc
sf

'-'.'/

sh
si
sk
si

Sill

sn
so
sp

sr
ss

St

English Term.

Air-funnel of the float.
Ring-chambers of the float (Dis-

conectse).
Basal dimple of the air-bell.
Radial muscles of tbe float.
Circular muscles of tbe float.
Top-opening of the float.
Pigment-cap of the float.

Radial pouches of tbe float.

Radial septa (between them).
Air-sac.

Air-tubules (Disconectas).
• Pneumatic umbrella.

Funnel-villi (Cystonectee).
Secondary exoderm of the float.
Top of the float.
Funnel-gate of the float.
Supporting plate of the float.

Tasters (Feelers).

Top of the taster.
Base of the taster.
Cavity of the taster.
Eye of the taster.
Pedicle of the taster.

Feeling filament*.

Suctorial-tubes.

Sij'h mics (Polijpites).

Sipho centralis (Disconectarum). Central polypite.
Basigaster. Basal chamber of the polypite.

Cavum siphonale. Cavity of the polypite.

Fissurae gastrales. Openings of the radial canals.

Bursa; gastrales. Pouches of the stomach.

Striae hepatieas. Liver-ridges.

Aster hepaticus(Disconectarum). Liver-star.

Valvula pylorica.
Labia oralia.
Stomacbus.
Siphones secundaria
Osculurn.

Pedunculus siphonalis.
Proboscis.
Discus suctorius.

Pyloric valve,
lips of the mouth.
Stomach.
Metasiphons.
Mouth.

Pedicle of the polypite.
Pharynx.

Suctorial disc of tbe mouth.
Tabula gastrobasalis (Disconec- Gastrobasal plate (between centra-
tarum). denia and central siphon).

(ZOOE. CHALL. EXP. — PART LXXVII. — 1888.)

German Term.

Lufttrichter der Scbwimmblase.
Ring-Kaminern der Luftflasche.

Basal-Grubehen der Luftflasche.
Liings-Muskeln der Schwimmblase.
Ring-Muskeln der Schwimmblase.
Scheitel-Offnung der Schwimmblase.
Farben-Kappe des Luftsacks.

Radial-Taschen der Pericyst-Hohle.

Radial-septen.

Luftsack.

Luftrbhren.

Luftschirm.

Trichter-Zotten des Luftsacks.
Luftflaschen-Tapete.
Schwimmblasen-Spitze.
Trichter-Pforte der Luftflasche.
Stiitzplatte der Schwimmblase.

Taster.

Taster-Spitze.

Taster-Basis.

Taster-Hoble.

Taster-Auge.

Taster-Stiel.

Fiihlfaden.

Saugrohren.

Central-Sipho.

Grundmagen.

Sipho-Hbhle.

Gastral-Ostien.

Ma^i-ntascben.

Leber-Streifen.

Leber-Canal-Stern.

Pylorus-Klappe.

Mund-Lippen.

Magen.

Neben-Siphonen.

Mund.

Sipho-StieL

Riissel.

Saugscheibe.

Magengrund-Platte.

Hhhh 4i>

578

THE VOYAGE OF H.M.S. CHALLENGER.

Latin Scientific Term.

English Term.

German Term.

sv

Sipho primarius (protosiphon).

Protosiphon.

Ursipho.

sv

Villi hepatici stomachi.

Hepatic villi.

Leber-Zotton.

sw

Plicas interna? stomachi.

Stomacb-folJs.

Magen-Falten.

sx

Siphones sexuales.

Sexual polypites (Disconecta?).

Gescblecbts-Sipbonen,

sy

Pylorus (sphincter stomacbi).

Pylorus.

Magen-Pfortner.

xz

Sphincter basalis.

Basal sphincter.

Basal Sphincter.

t Tentacula (Filamenta).

fa Ampulla terminalis tentilli.

th Basis tentaculi.

tc Cornua lateralia tentilli.

id Tentaculum primarium.

te Filum terminale tentaculi.

tf Filum terminale tentilli.

tg Suspensorium (mesenterium).

th Involucrum (pallium cnidosacci).

ii Internodia tentaculi.

tk Cnidotsenia (cnidosaccus ten-
tilli).

// Ligamenta elastica tentilli.

tm Musculi tentaculi.

in Nodi tentaculi.

in Ampulla basalis (Pbysalidarum).

ip Pedunculus tentilli.

tq Cnidosphseria terminalia (Dis-
conectarum).

tr Annuli tentaculi.

is Tentilla (tentaculi rami later-
ales).

// Tentilli basis (insertio).

In Insertio subumbralis tentaculi
(Disconectarum).

tv Villi tentaculi exodermales.

in- Verrucse tentaculi.

ty Ocelli involucri.

tz Calcar tentilli.

u Umbrella.

ua Apex umbrella?.

nb Basis umbrella?.

uc, Centradenia (Disconectarum).

ud Facies dorsalis umbrella;.

ue Exumbrella.

uf Velarium (Velellidarum).

ug Facies basalis umbrella?.

uh Hepar (Disconectarum).

ui Infundibulum (hydrceciuni).

c/,' Valvula infundibuli.

Capturing filaments.

Terminal vesicle of the tentillum.
Basal portion of tbe tentacle.
Lateral horns of the tentillum.
Larval tentacle.

Terminal filament of the tentacle.
Terminal filament of the tentillum.
Ventral band of tbe tentacle.
Mantle of the sacculus.
Internodes of the tentacle.
Sacculus (urticating band).

Angle-bauds (of the cnidotamia).
Muscles of the tentacle.
Nodes of the tentacle.
Basal sac of the tentacle.
Pedicle of the tentillum.
Terminal cnidospheres.

Kings of the tentacles.

Lateral branches of tbe tentacle
(Accessory tentacles).

Insertional base of the tentillum.

Insertional-facettes of the ten-
tacles.

Exodermal villi of the tentacle.

Exodermal tubercles.

Ocellar spots of the sacculi.

Spur of tbe tentillum.

Umbrella.

Top of the umbrella.

Base of the umbrella.

Central gland.

Dorsal face.

Convexity of tbe umbrella.

Sail of the float of the Velellidae.

Basal face of the umbrella.

Lifer (of the centradenia).

Funnel-cavity.

Valve of the funnel.

Fangfiiden.

Endblase des Tentills.
Basal-Stiick des Tentakels.
Seiten-Hbrner des Tentills.
Larven-Tentakel.
Endfaden des Tentakels.
Endfaden des Tentills.
Tentakel-Leitband.
Mantel des Nesselknopfs.
Tentakel-Segmente.
Nesselband des Tentills.

Elastische Bander des Nesselknopfs.

Tentakel-Muskeln.

Tentakel-Knoten.

Basal-Blase des Tentakels.

Tentillen-Stiel.

Endf aden-Nesselkugeln .

Tentakel-Ringe.

Seitenfaden des Tentakels (Tentillen).

Tentillen-Insertion.
Tentakel-Insertions Narben.

Exoderm-Zotten des Tentakels.
Nesselwarzen des Tentakels.
Augenfiecke der Nesselknbpfe.
Tentillen-Sporn.

SiJrirm.

Schirm-Scheitel.

Schirm-Grund.

Central-Druse (der Disconecten).

Eiickenflache des Schirms.

Ober-Schirm.

Segel der Schwimmblase.

Grundfliiche.

Leber (der Central-Druse).

Stamm-Gehause,

Gehaus-Klappe.

REPORT ON THE SJPIIONOPHORyE.

379

Latin Scientific Term.

u.I Facies sinistra umbrellae.

'i in Margo umbrella?.

un Nephros (Diseonectarum).

no Ostium umbrella.-.

uji Peduuculus umbrellae.

vi/ /Equator umbrellae.

in- Plica? radiales umbrellee (Dis-
eonectarum).

us Glandules marginales (Diseo-
nectarum).

ut Sulcus tentacularis umbrella?.

uu Limbus umbrellae.

uv Facies ventralis umbrella'.

//"■ Cavitas umbrell;''.

u.r Facies dextra umbrella'.

111/ Ocelli marginales.

uz Fulcrum (gelatina umbrella').

r Velum.

w Suhumbrella.

English Tehm.

Left-band face.
Umbrella-margin.
Kidney (of tbe centradenia).
Mouth of tbe umbrella.
Pedicle of tbe umbrella.
Equatorial periphery.
Radial folds of the umbrella.

Muciparous glands of the umbrella-
margin.
Ring furrow of the umbrella.
Limb of the umbrella.
Ventral face.

Concavity of the umbrella.
Eight-hand face.

Eye-spots on the umbrella-margin.
Jelly-mass of the umbrella.

Vdum (Nectoring).

Nectosae.

x Organa indefinita.

>/ Cystones.

Undetermined orga ns
Anal vesicles.
Full- rum (Lamina fulcralis). Supporting plate.

German Term.

Linke Schirmflache.

Schirra-Rand.

Niere (der Central-Druse).

Schirmhohlen-Miindung.

Schirm-Stiel.

.Equator des Schinns.

Stern-Falten des Oberschirms.

Schleimdriisen des Schirmrandcs

(der Disconecten).
Tentakel-Kranz-Furche.
Sehirni-Saum (der Disconecten).
Lauchnache.
Unter-Schirm.
Rechte Schirmflache.
Augen am Schirmiande.
Schirmgallerte.

Seliirimmrim:.

Scliwimmsack.

I 'nlii'xliiiniitr Organ .

Afterblasen.

Stiitzplatte.

:;s(i

THE VOYAGE OF H.M.S. CHALLENGER.

APPENDIX.

Statistical Synopsis of the numbers of families, genera, and species of Siphonophorse
enumerated in this Eeport : —

Orders.

Plates of
the Report.

Pages of
the Report.

Families.

Genera.

Species.

ECTJS, .

II. Calyconect.e, .

III. Phtsonectj;, .

IV. AukonectjE,

V. CystonectjE, .

XLIII.-L.

XXVII.-XLII.

VIII. -XXI.

I.-VII.
XXII.-XXVI.

26-88

89-183

184-280

281-304

305-352

3
6

8
2

5

9
29
29

4
14

36
94
75
5
30

Total,

24

1

85

240

PLATE I.

Order AURONECM.

Family Rhodalid*.

Rhodalia miranda.

(ZOOL. CHALL. EXP. PART LXXVII. 1888.) Hllllh.

Diam.

PLATE I.

Rhodalia miranda, n. sp. (p. 302).

Fig. 1. Apical view of the corm (from above). The large spheroidal pneuma-
tophore (p) is surrounded by the corona of pyriform nectophores (n).
This corona is bisected in the sagittal axis by the aurophore (I) on the
dorsal side, and by the series of buds (i) on the ventral side, v, Velum ;
n\ opening of the nectosac. . . . . . x 2

Fig. 2. A single cormidium, composed of a very contracted cylindrical siphon (s)
and two gonodendra. One gonostyle bears a long sexual palpon (r).
sh , Strire hepaticse ; sr, proboscis ; so, mouth, . . x 15

Fig. 3. A single gonodendron, with two main branches, bearing clusters of
numerous pear-shaped ovaria (f) and scattered spindle-shaped sper-
maria (h). c, Spirally twisted canal of the contracted gonostyle, . x 15

Fig. 4. Transverse section through a gonostyle, or the stem of a gonodendron.
The transverse section through the basal pedicle of a siphon exhibits
nearly the same structure. c, Central canal ; d, entoderm ; e, exo-
derm ; ;, structureless, cartilaginous, supporting plate ; z1, its radial
branched apophyses covered outside by the transverse sections of
longitudinal muscles (ml). Inside, between it and the entoderm, a
thin layer of ring-muscles (mc), . . . . x 70

Fig. 5. A fragment of the same transverse section. Characters as in fig. 4, . x 200

[lie Voyage of 11 \I S Cha]

Siphonophorae PI. I.

a.— A

■

RHODALIA MIRANDA

PLATE IT.

Order AURONECm

Family Rhodalida
Rhodalia miranda

Diani.

PLATE II.

Rhodalia miranda, n. sp. (p. 302).

Fig. 6. Basal view of the conn (from below). The tentacles are detached and
the siphons highly contracted. The whole convex basal surface of
the corm is covered by radish-shaped cormidia, each of which is usually
composed of a siphon (s) and one or two gonodendra (g). The necto-
phores (n) form a peripheral corona, v, Velum ; w, opening of the
nectosac (compare p. 290), . . . . . . x 2

Fig. 7. A single branch of a clustered gonodendron, with numerous pear-
shaped gynophores and single, scattered, spindle-shaped andro-
phores, . . . . . . . . x 50

Fig. 8. A single branch of a gonodendron, with two monovonian and two

polyovonian gynophores, . . . . . x 50

Fig. 9. Longitudinal section through a polyovonian gynophore. c, Gastral
cavity ; d, entoderm ; e, exoderm ; o, ovules ; o1, nucleolus (germinal
spot); d1, nucleus (germinal vesicle); o3, protoplasm of the egg-cell
(germinal yolk), . . . . . . x 150

Fig. 10. Transverse section through a polyovonian gynophore. Characters as

in fig. 9, . . . . . . . . x 150

Fig. 11. A pyriform polyovonian gynophore, from the outside of which arise

two secondary monovonian gynophores, . . . x 50

Fig. 12. An ovate monovonian gynophore, the umbrella of which exhibits eight

distinct radial canals (instead of the usual four), . . x 50

TheVoyage of II M i '

Siphonophorae I'l U

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RHODALIA MIRANDA

PLATE III.

Order AUEONECT.E.

Family Rhodali dje.
Rhodalia miranda.

(ZOOL. OHALL. EXP. — PART LXXVII. — 1888.) — Hllhh.

PLATE III.

Rhodcdia miranda, n. sp. (p. 302).

Fig. 13. Lateral view of the eorm (from the left side), somewhat diagrammatic.
The triple corona of nectophores may exhibit in the living animal a
somewhat different form ; all the nectophores of the spirit-specimens
examined were strongly contracted and altered by the action of the
alcohol ; the majority, too, were detached from the stem. The
siphons and tentacles were all detached from the trunk, also very
highly contracted, and it is probable that they exhibit in living
specimens a larger size and a more peculiar form. The upper half of
the figure exhibits the nectosome from the left side ; most necto-
phores in the right half of the figure are removed, in order to show
the high insertions of their lamellar pedicles. Beyond the cap-shaped
apical pneumatophore the dorsal aurophore is visible on the right
hand. The lower half of the figure exhibits the siphosome, densely
covered with numerous cormidia, each with a contracted siphon,
a long tentacle, and a clustered gonodendron (compare p. 290),

Fig. 14. Dorsal view of the same corm. The majority of the nectophores are
removed from the trunk of the nectosome, the high insertions only
of their lamellar pedicles being visible. A few nectophores remain
on the right and left. Beyond the cap-shaped apical pneumato-
phore is visible in the median dorsal groove of the trunk the
spheroidal aurophore, with its external opening, the aurostigma.
The trunk of the siphosome (in the lower half of the figure), and
the numerous cormidia covering it, are highly contracted ; all the
tentacles are detached ; between the clustered gonodendra are
visible the strongly retracted siphons, ....

Diam.

i Voyage ol H.M.S CI

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RHODALIA MIRANDA.

PLATE IV.

Order AURONECTiE.

Family Rhodalid*.

Rliodalia miranda.

Diam.

PLATE IV.

Rhodalia miranda, n. sp. (p. 302).

Fig. 1 5. Sagittal section through the complete corm, in the vertical median plane, p, Pneumato-
phore ; pa, its wide cavity filled with air ; I, aurophore ; Im, its pistil ; lo, its external
opening (aurostignia); i, ventral series of buds ; n, young ventral nectophore ; np, peduncle
of a dorsal nectophore ; a, cartilaginous bulb of the trunk ; ac, reticulum of the trunk-
vessels ; aa, large flat hypocystic cavity of the trunk, beyond the pneumatophore ;
ah, cormidia ; g, gonodendron ; r, gonopalpon ; s, siphon, . . . . x 2

Fig. 16. Apical view of the corm (from above), after removal of the nectophores and the greatest part
of the pneumatophore ; the horizontal section lying somewhat above the bottom of the
float (pa). The corona of white rays, which surrounds it, represents the transverse sections
of the pedicles of the nectophores (np1), and this is surrounded by the peripheral corona
of cormidia (</). The auroduct (or the central canal of the aurophore, la) opens inside
by the auropyle (li), outside by the aurostigma. pi, Foveola ; I, aurophore (in the
median line of the dorsal side) ; Ir, radial chambers of the aurophore ; l, series of buds (in
the median line of the ventral side); ie, dorsal canal of the trunk (for the buds); np,
peduncle of the nectophore ; g, corona of the gonophores. A single nectophore (n)
remains, v, Velum ; w, ostium of the suburnbrella.

Fig. 17. Series of buds on the ventral side of a young corm (blastocrene of the siphosome), immediately
beyond the pneumatophore. n, Young nectophore ; nc, its ring-canal ; v, velum ; to, sub-
umbrella ; ah, cormidia, or groups of buds, developed in a spiral ; each group being
composed of a siphon (s) and a gonodendron (g), . . . . . . x 5

Fig. 18. A young gonodendron, with two branches, one of which bears a long cylindrical palpon (a).

ga, Gonostyle ; gc, its canal; </, gonophores, . . . . . x 10

Fig. 19. A single siphon, sp, Pedicle ; ml, longitudinal muscles of the stomach ; sh, remnants of

the hepatic stripes ; sr, proboscis ; so, mouth, . . . . . . x 1

Fig. 20. A detached siphon, connected with its tentacle, xp, Pedicle of the siphon ; sh, hepatic ridges;

sr, proboscis ; /, tentacle ; ts, tentilla (compare pp. 290 to 292), . . . . x 5

Fig. 21. Transverse section of a tentacle, c, Central canal ; d, entoderm ; me, ring-muscles ; z, ful- '

crum ; ml, longitudinal muscles; e, exoderm (compare p. 292), . . . . x 100

Fig. 22. A portion of a tentacle with the insertions of the tentilla (fo). tr, "Rings of the tentacle, . x 20

Fig. 23. A single tentilluni. tb, Basal pedicle : ik, cnidoband ; tkv large lateral cnidocysts ; tkn, small

median cnidocysts ; tl, elastic ligament (angle-band); If, terminal filament, . . x 200

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RHODALIA MIRANDA.

PLATE V.

Order AURONECLE.

Family Ehodalidj.
Rhodalia miranda.

(HOOL. CHALL. EXP. PART IiXXVII. — 1888.) — Hllllll.

PLATE V.

All the figures of this Plate, except figs. 30 and 31, represent different sections through the aurophore.

Rhodalia miranda, n. sp. (p. 302).

Diam.

Kg. 24. Sagittal section through the aurophore and the neighbouring parts of the pneumatophore.
The thick wall of the pyriform medusoid aurophore contains a lacunar system of
wide irregular canals (//•), separated by radial, irregularly branched septa. The auro-
stigma (lo), or the distal opening of the aurophore, leads into a narrow central axial
canal (la), and the proximal end of this auroduct, the auropyle (li), opens into the large
cavity of the pnoumatocyst (j>a). The auroduct is placed in the axis of a muscular cylin-
der, the pistil (lp), which fills up the subumbrellar cavity of the medusoid aurophore.
The pistil is surrounded by a thickened cylindrical cuticular vagina (If), seemingly the
distal prolongation of the pneumatocyst {pf). ps, Pericystic cavity (between outer, z,
and inner, z1, wall of the pneumatophore) ; ac, gastral canals of the trunk, traversing its
hyaline cartilaginous jelly-substance (z1); z, fulcrum ; d, entoderm ; e, exoderm, . x 1

Fig. 25. Frontal section (or vertical transverse section) through the basal part of the aurophore of
another specimen, la, Axial canal of the pistil ; le, its lining epithelium (exodermal) ;
//', longitudinal muscles of the pistil (seen in transverse section); If, vagina pistilli
(cuticular tube); e1, exoderm of the inner wall of the aurophore (subumbrella ?); e1, exoderm
of its outer wall (exumbrella ?) ; d, entoderm ; z, fulcrum : lr, radial pouches and lacunar
canals, with radial septa between them. The upper part of the figure exhibits the insertion
of the aurophore at the dorsal base of the pneumatophore. pf, Pneumatocyst ; pa,
cavity of the pneumatocyst, . . . . . . . x 15

Fig. 26. Frontal section through the middle part of the aurophore of the same specimen. The

characters are the same as in fig. 25, . . . . . . x 15

Fig. 27. A small fragment of the exumbrella (or the outer wall) of the aurophore, taken from the
transverse section, fig. 26. Two inner folds of the exumbrella are seen in vertical section
(through their fulcral axis), e, Exoderm; z, fulcrum; d, entoderm, . . x 150

Fig. 28. A small portion of a longitudinal section through the pistil of the aurophore. la, Axial
canal (auroductus) ; le, its epithelium ; 7m, bundles of parallel, longitudinal, spindle-shaped
cells (apparently muscle-cells) ; In, their nuclei ; outside is the vagina pistilli (cuticular
tube, compare fig. 24), ...... . . x 300

Fig. 29. Transverse section through a canal (ac) of the reticulum of the trunk ; the entodermal epi-
thelium (d) of the canal is simple, and surrounded by the hyaline structureless fundamental
substance of the cartilaginous support, . . . . . x 150

Fig. 30. A small portion of a vertical section through the pneumatocodon (or the exumbrella of the
pneumatophore). One of the simple or forked bands of entoilerm-cells (<?j), which tra-
verse the cartilaginous fulcrum (~), connects the entoderm of the exumbrella (d) with its
exoderm (e), . . . . . . . . . x 150

Fig. 31. Lateral view of the inferior part of the lamellar peduncle of a nectophore. The fine parallel
stripes (vertical in the figure) are horizontal (or radial) muscle-fibrillas (nm). A strong
peduncular canal (>/.<), arising from the trunk, runs along the inferior free horizontal
margin of the peduncle (right hand of the figure), and gives off a series of twenty to thirty
small, simple, secondary canals (ul). These ascend vertically ; their size decreases from
the inner (axial) towards the outer (abaxial) margin of the peduncle, . . x 15

Siphonophorae Pl.V

RHODALIA MIRANDA

PLATE VI.

Order AURONECTiE.
Family Stephalid^e.

Stcphonalia bath >j] >h ysa.

Diam.

PLATE VI.

Stephonalia bathyphysa, n. sp. (p. 299).

N.B. —Since this species was formerly confused by me with Stephalia corona, it bears the

name of this species on the Plate.

Fig. 32. Lateral view of the corm, from the left side, p, Pneumatophore ;
I, aurophore ; n, nectophore ; s, siphons ; t, tentacles ; g, gono-
dendra ; ap, protosiphon, . . . . . . x 4

Fig. 33. Dorsal view of the same corm. Characters as in fig. 32. Jo, Auro-

stigma, . . . . . . . . x 4

Fig. 34. Apical portion of the siphosome of another corm, exhibiting the spiral
series of young cormidia, which are developed immediately beyond
the pneumatophore (p). The single cormidia are isolated and more
highly magnified in figs. 35-38. s, Siphons ; t, tentacles ; g, gono-
dendra ; n, nectophores.

Fig. 35. A group of six cormidia, arising from a common pedicle (ah). The
numbers I.-VI. mark the succession in age and size ; I. is the
youngest, VI. the oldest cormidium. s, Siphons ; sg, stomach
(with eight to twelve dark liver-stripes, sh) ; sr, proboscis ; sr\
the same reflexed ; t, the annulated tentacle ; tf, its terminal
filament ; g, gonodendra, . . . . . x 20

Fig. 36. A very young cormidium, with a few buds.

Fig. 37. A single isolated cormidium. Characters as in fig. 35. sp, Pedicle of

siphon ; sb, basigaster ; q, gonopalpon, . . . x 20

Fig. 38. A single, well-developed cormidium, to the basal pedicle of which is

attached a cluster of very young, incipient cormidia, . x 20

The Voyage of II M SrChallenger'.'

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STEPHALIA CORONA

PLATE VII.

Order AUKONECTiE.

Family Steph aliD/E.

Stephalia corona.

Figs. 42, 46, Rhodalia miranda.)

(ZOOL. CHALL. EXP. — PART LXXVII. 1888.) Hhllll.

PLATE VII.

Stephalia corona, n. sp. (p. 297).

Diani.

Fig. 39. Lateral view of a young corm (in profile, from the right side), p, Pneumatophore ; 1, auro-
phore ; lo, auropyle ; n, corona of nectophores ; uo, ostium of the nectosac ; cc, ring-canal ;
s, siphons ; t, tentacles ; below, central siphon (basal opening of the trunk), . x 10

Fig. 40. Sagittal section through the same corm ; signification of the characters the same as in fig. 39.
Beyond the pneumatophore (p) is visible the hypocystic cavity (ah), and on its dorsal side
the aurophore (I). From the centre of the hypocystic cavity arises the central axial canal
(ea); it passes through the vertical axis of the cartilaginous trunk (a), gives off numerous
anastomosing branches (ac), and opens through the mouth of the central siphon (ap).
i, Ventral series of buds. Each siphon («) bears a simple tentacle (t) on the dorsal
side of its base, but no gonodendron, . . . . . . x 1 0

Fig. 41. The distal end of another corm. ao, The prostoma, or the basal mouth-opening of the

primary siphon (afterwards the axial canal, ca, of the trunk, ap), . . x 20

Fig. 42. A single siphon of Rlwdalia miranda, with a tentacle, sp, Pedicle ; sb, basigaster ; sg, stomach ;
sh, hepatic ridges ; sr, proboscis ; so, mouth ; tr, rings of the tentacle ; tg, its suspensorium ;
tt, insertions of the tentilla (ts); these are lost in the distal part (at the right hand), . x 10

Fig. 43. Two large ensiform cnidocysts, from the lateral series of the tentillum ; a. closed ; b, opened,

with protruded cnido-filament, . . . . . . . . x 400

Fig. 44. Bud of a nectophore, in longitudinal section, np, Peduncle ; w, subumbrellar cavity ; v,

incipient velum ; e, gastral cavity ; d, entoderm ; e, exoderm ; z, fulcrum, . . x 100

Fig. 45. Bud of a nectophore, in transverse section. Characters the same as in fig. 44. The four

radial canals (nr) are visible, between the cathamma (d), . . . . x 100

Fig. 46. A mature androphore of Rlwdalia miranda. hs, Spermarium ; hx, spadix ; hr, radial canals

of the umbrella (u) ; uo, ostium of the umbrella, . . . . x 50

Fig. 47. Muscle-epitheliuni of the outside of the pneumatophore. e, Exoderm-cells, . . . x 300

Fig. 48. Lateral view of a corm of Stephalia corona (from the right side), p, Pneumatophore ;
I, aurophore ; n, nectophores ; np, their pedicles ; v, velum ; s, siphons ; so, their mouth-
openings ; g, gonophore-buds ; ap, protosiphon, . . . . . . x 5

Fig. 49. A single cormidium of another specimen, ah, Common pedicle of the cormidium ; s, siphon;

so, its mouth ; ga, gonostyle ; /) gynophores ; o, eggs ; h, androphore, . . x 50

Fig. 50. A young larva (Auromda). pa, Cavity of the pneumatophore ; I, aurophore ; Im, its pistil ;
lo, aurostigma ; ap, primary siphon ; sc, its cavity ; ao, its mouth ; e, exoderm ; d,
entoderm, . . . . . . . . . x 10

The Voyage of H.M.S Cha

1 VII

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48.

STEPHALIA CORONA

PLATE VIII.

Order PHYSONECM.

Family Forsk alida
Forskalia tholoides.

PLATE VIII.

Foi'sJcalia tholoides, n. sp. (p. 244).

Fig. 1. Lateral view of a complete corm, drawn by me from life in Lanzerote,
in December 1866. The cupola-shaped nectosome bears on the
top a small red pneumatophore, and is composed of very numerous
nectophores, arranged like the scales of a fir-cone in a Inotropic
spiral series. The siphosome exhibits numerous siphons which
are attached to the axial stem by long radial pedicles, and arranged
in a dexiotropic spiral series. The stomachs of the siphons are red.
Each siphon bears on its base a long tentacle, beset with a series
of numerous tentilla ; the cnidobands of the latter are also pink.
The whole surface of the siphosome is covered with large dentate
bracts, ........

Figs. 2-5. Lateral view of four isolated nectophores (2 and 3 fully developed,
4 and 5 young ones), np, Triangular pedicle ; nb, its base of in-
sertion into the trunk ; ns, canal of the pedicle ; nr, four radial
canals ; nc, ring-canal ; v, velum, . . .

Diam.

fheVoyaeeol H.M.S."Challen*er!'

Siphonophorae PI Y!II.

■

FORSKALIA THOLOIDES

PLATE IX.

Order PHYSONECT^.

Family Forskalid^e.

Forskalia tholoides.

(ZOOL. CHALL. EXP.— PART LXXVII. — 1888.)— Hhhll.

PLATE IX.

Forskalia tholoides, n. sp. (p. 244).

Fig. 6. Apical view (from above) of a complete corm (without nectophores and bracts),
preserved in spirit, in a state of extreme contraction. All the nectocalyces
and the hydrophyllia are detached. The nectosome exhibits beyond the
pneumatophore (p) a multiple series of small tubercles, the basal insertions of
the pedicles of the detached nectophores (n). The shortened trunk of the
siphosome (a) is vesicular and inflated. The siphosome exhibits the dexiotropic
spiral line in which the loose cormidia are arranged. s, The contracted
siphons ; t, tentacles ; q, palpons ; r, palpacles ; i, buds.

Fig. 7. A single loose cormidium, attached to the articulated trunk, with a single
siphon and a single tentacle. The long extended pedicle of the siphon
(sp) is covered by some denticulate bracts or hydrophyllia (b). From the
thickened basal part of the siphon (sb) there arises the long articulated tentacle
bearing numerous tentilla, each with a spiral cnidoband (k). The dilated
stomach of the siphon (sm) exhibits sixteen longitudinal hepatic ridges (sh),
eight longer alternating with eight shorter, sr, Proboscis ; so, mouth. A
pediculate gonopalpon (q) bears on its base a thin palpacle (?") and a clus-
tered monostylic gonodendron, composed of proximal gynophores (f) and
distal androphores (h). qp, Pedicle of the palpon ; behind the gonopalpon is
a cyston ; b, bract ; an, nodal constrictions of the trunk, from which all
the appendages arise ; at, internodes ; ac, red central canal of the trunk.

Fig. 8. A single siphon, highly contracted, so, Mouth ; si, sixteen radial folds of the
reflexed proboscis ; sm, stomach with sixteen red hepatic ridges ; sb, four
square cnidal plates of the basigaster ; sp, pedicle of the siphon ; t, tentacle
(arising in the constriction between pedicle and basigaster).

Fig. 9. Two cnidal nodes of the mouth-opening ; from each arise two longitudinal
glandular ridges, running between the muscles inside the proboscs.

The Voyage of lUt.S ."Challenger:

Siphonophorae PI. IX

E KaecW ami

FORSKALIA THOLOIDES

PLATE X.

Order PHYSONECT^E.

Family Forskalid^e.

Forskalia tholoides.

PLATE X.

Forskalia tlwloicles, n. sp. (p. 244).

Figs. 10-18. Different forms of detached kydrophyllia or bracts.

Fig. 10. Lateral view of a small bract.

Fig. 11. Facial view of the same.

Fig. 1 2. Lateral view of another small bract.

Fig. 13. Facial view of the same.

Fig. 14. Dorsal view of another bract.

Fig. 15. Lateral view (profile) of the same.

Fig. 16. Transverse section of the same.

Figs. 17, 18. Two larger bracts of different forms.

Fig. 19. An isolated cyston (q), with its palpacle or tasting filament (r). qp, Pedicle,
compare p. 246.

Fig. 19 — A, B, C. Three different states of contraction of the palpacle (fig. 19).

Fig. 20. A single palpon, separated from its pedicle by a basal cnidoring (qb) (p. 247).

Fig. 21. A single pediculate gonodendron. q, Gonopalpon or sexual palpon, bearing on
its base a pair of crescentic cnidonodes (qb) ; ga, cluster of gonophores ;
f, gynophores ; h, anclrophores ; qp, gonostyle (common pedicle of the palpon
and the gonodendron).

Fig. 22. An isolated androphore. uo, Umbrella aperture ; hx, spadix ; hs, spermarium ;
hp, pedicle.

Fig. 23. A single tentillum, arising from a nodal constriction of the tentacle (tn).
ts, Pedicle ; tic, cnidoband ; tf, terminal filament.

Fig. 23 — A, B, C, D. Four different stages of contraction of the terminal filament
{tf fig. 23).

Fig. 24. Apex of the pneumatophore, with four pairs of pigment radii (p. 244).

rhcVoya^eof H.M.S."CWlenoci

Siphoiiophorae I 'I X

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FORSKALIA THOLOIDES.

PLATE XL

Order PHYSONECTvE.

Family Anthophysida

Athorybia ocellata.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) — Hhhb.

PLATE XI.

The figures of this Plate were painted by nie from living specimens, which I observed in the
Canary Island Lanzerote, December 29, 1866.

Athorybia ocellata, n. sp. (p. 276).

Fig. 1. Lateral view of the complete corm, in an expanded state, quietly floating at the
surface of the sea (xy). The pneumatophore (p) bears a red pigment-cap and
is surrounded by a corona of crescentic elegantly ribbed bracts (b). Between
these are numerous prominent palpons (q), with a red ocellus on the apex (qo).
Below depend five siphons and tentacles ; ss, suctorial disc of the mouth.

Fig. 2. Apical view of the same corm (from above).

Fig. 3. A single siphon, sp, Pedicle; sb, basigaster; sin, stomach; sr, proboscis; so,
mouth (p. 277).

Fig. 4. A single palpon. qp, Pedicle; qo, ocellus (with a lens?); qc, terminal corona of
cnidocysts.

Fig. 5. Lateral view of the isolated pneumatophore.

Fig. 6. Apical view of the same, with the octoradiate pigment-cap (mitra ocellaris).

TheVoyageolH M.S.'Challenger

Siphonophorae I'l l\

U> h

ATHORYBI A OCE LLATA

PLATE XII.

Order PHYSONECM.

Family Anthophysi d.e.

Figs. 7-9. Anthophysa dariuinii.
Figs. 10-18. Athorybia ocellata.

PLATE XII.

Figs. 7-9. Anthophysa darwinii, n. sp. (p. 278).

Fig. 7. Dorsal view of the complete corm, after the detachment of the bracts. The
ovate pneumatocyst (p) exhibits above an octoradiate pigment-star, below a
corona of sixteen radial septa, bp, Basal insertions of the lamellar pedicles
of bracts ; ib, buds of bracts, on the top of the nectostyle ; below, trunk of
the nectosome ; q, palpons.

Fig. 8. Lateral view of the same corm, without bracts (from the left side). Characters
as in fig. 7. The ventral side of the pneumatophore is embraced by the
cucullate nectostyle (am) ; (compare p. 279).

Fig. 9. Ventral view of the same corm. Characters as in fig. 7. Two bracts only
(b, at the left hand) are preserved, is, Ventral series of buds of cormidia (in
the median ventral line of the siphostyle, p. 270).

Figs. 10-18. Athorybia ocellata, n. sp. (p. 276, PI. XL).

Fig. 10. Longitudinal section through a contracted siphon, sp, Pedicle ; sb, basigaster ;
sm, stomach ; sv, hepatic villi ; sr, proboscis ; so, mouth.

Fig. 11. Ventral view of a tentillum. ts, Pedicle ; tk, cnidosac ; tc, lateral horns ; ta,
terminal ampulla.

Fig. 12. Dorsal view of a tentillum ; tz, dorsal spur. Characters as in fig. 11.

Fig. 13. Lateral view of a tentillum (left side). Characters as in figs. 11, 12. (For the
right hand ta read tz.)

Fig. 14. Transverse section of a bract, be, Brae teal canal ; bk, cnidal ribs on the dorsal
side.

Fig. 15. Exodermal epithelium of the margin of a bract, br, Cnidal marginal band, with
pigment ; k, cnidocysts.

Fig. 16. Exodermal epithelium of a dorsal rib of a bract, bk, Patches of pigment and
cnidocysts.

Fig. 17. A male gonodendron. gp, Its pedicle; h, androphores ; lip, their pedicles";
hx, spadix ; hs, spermarium ; uo, ostium umbrelke.

Fig. 18. A female gonodendron. gp, Its pedicle; /, gynophores ; fp, their pedicles;
o, eggs ; uo, ostium umbrellas.

The Voyage of H.M.S ."Challenger"

Siphonophorae PI. XII

ATHORYBIA OCELLATA

PLATE XIII.

Order PHYSONECT^E.

Family Nectalid.«.
Nectalia loligo.

(ZOOL. CHALL. EXP. -PART LXXVII. — 1888.)— Hllhh.

PLATE XIII.

Drawn from life by me in Lanzerote, January 15, 1867

Nectalia loligo, n. sp. (p. 252).

Fig. 1. Lateral view of the complete corm. The trunk of the nectosome bears an apical pneumatophore (p),
with pneumatocyst (pf), and two opposite rows of nectophores (n). The shortened trunk of the
siphosome bears a corona of bracts, and beyond it siphons (s), palpons and tentacles (t); in, buds
of nectophores.

Fig. 2. The same corm in the contracted state, after the detachment of the nectophores. pf, Pneumatocyst ;
in, buds of nectophores; is, buds of siphons; sb, basigaster; sm, stomach; sv, hepatic villi;
sr, proboscis ; so, mouth ; yh, cystons ; yo, their distal opening (anus 1).

Fig. 3. The trunk alone, after the detachment of the appendages (lateral view from the left side), am, Necto-
style (trunk of the nectosome) ; p, pneumatophore ; pf, pneumatocyst ; in, buds of nectophores ;
as, vesicular siphostyle (trunk of the siphosome) ; is, buds of siphons and palpons.

Fig. 4. The pneumatophore (much contracted in spirit), px, Apex ; pb, basis ; pf, pneumatocyst ; pr, four
radial septa ; ps, pouches between them ; in, buds of nectophores , am, trunk of the nectosome.

Fig. 5. A young nectophore, from the ventral side.

Fig. 6. An adult nectophore, from the dorsal side, w, Subumbrella ; cl, left canal; ex, right canal; cp, pedi-
cular canal ; v, velum.

Fig. 7. Basal view of a nectophore. no, Ostium ; v, velum ; cc, ring-canal.

Fig. 8. Lateral view of a nectophore, from the left side, cl, Left canal ; rp, pedicular canal.

Fig. 9. Ventral view of a sagittal bract, lib, Basal pedicle ; cb, ventral canal of the bract.

Fig. 10. Lateral view of an intermediate (diagonal) bract. Characters as in fig. 9. bd, Dorsal crest.

Fig. 11. Dorsal view of a lateral bract. Characters as in figs. 9, 10.

Fig. 12. Lateral view of the same lateral bract.

Fig. 13. A siphon, sb, Basigaster; sm, stomach, with hepatic villi (sv) ; sr, proboscis; so, mouth.

Fig. 14. A tentillum (lateral branch of a tentacle), ts, Pedicle; tkv basal ampulla; thy,, cnidoband ; t!in,
cnidosac ; tkln, terminal ampulla ; tf, terminal filament.

Fig. 15. Two small paliform cnidocysts, from the distal portion of the cnidoband.

Fig. 16. Two large ellipsoidal cnidocysts, from the basal portion of the cnidoband.

TheAbyage of 11 Ms Challenger!

Siphonophoiae PI. XH1.

N ECTALI A LOL1GO

PLATE XIV.

Order PHYSONECTyE.

Family AgalmiDjE.
Anthemodes ordinata.

PLATE XIV.

Drawn from life by rue in Lanzerote, January 25, 1867.

Anthemodes ordinata, n. sp. (p. 229).

Fig. 1. The complete corin, in the expanded state. The nectosome (seen from the
lateral side) is composed of a small apical pneumatophore and two opposite
rows of nectophores. The long tubular trunk of the siphosome is densely
covered with prismatic bracts, and bears numerous ordinate and equidistant
cormidia, each composed of a siphon, a tentacle, a cyston, and two gonodendra,
a male and a female. (Compare PI. XV. fig. 5.)

Fig. 2. The nectosome of the same corm, seen from the ventral (or dorsal) side.

Fig. 3. A single nectophore, dorsal view (from above and outside).

Fig. 4. A single nectophore, lateral view (from the left side).

Th€VcyageofH.M.S."Cha!Iengi

Siphonophorae PJ.XIV.

llschDel.

-

ANTHEMODES ORDINATA

PLATE XY.

Order PHYSONECT^E.
Family Agalmidj;.
Anthemodes ordinata.

(ZOOL. CHALL. EXP. PART LXXVII. — 1888.) — Hhhh.

PLATE XV.

Anthemodes ordinata, n. sp. (p. 229).

Fig. 5. A single cormidium. s, Siphon ; sm, stomach ; sr, proboscis ; ss, suctorial disc ;
t, tentacle ; y, cyston ; yo, its mouth (anus) ; b, bracts ; cb, bracteal canal ;
h, androphores ; f, gynophores.

Fig. 6. A single cormidium, attached to the trunk («), without gonodendra. Characters
as in fig. 5 ; ts, tentilla ; k, cnidosac ; so, mouth of the siphon.

Fig. 7. A single siphon, sp, Pedicle ; sm, stomach ; sv, hepatic villi (in four rows) ;
sr, proboscis ; so, mouth ; t, tentacle ; k, cnidosac.

Fig. 8. A single cyston. yp, Pedicle ; y, excretory vesicle ; yc, concretions ; yo, mouth.

Fig. 9. Distal end of a cyston, with opened mouth, or rather anus (yo).

Fig. 10. Edges of a bract, with their rows of cnidocysts.

Fig. 11. A single tentillum. ts, Pedicle; tv, its villi; kg, large proximal cnidocysts;
km, median paliform cnidocysts ; below, distal pyriform cnidocysts ; tf,
terminal filament.

Fig. 12. A young tentillum with involucre. Characters as in fig. 11.

Fig. 13. A young tentillum without involucre. Characters as in fig. 11.

Fig. 14. A single androphore ; hu, umbrella ; hx, spadix ; he, central canal ; hs,
spermarium.

Fig. 15. A single gynophore. fp, Pedicle; cp, its canal ; fa, umbrella ; xm, network
of spadicine canals ; o, ovule. ; o1, germinal spot ; o2, germinal vesicle ; o3,
germinal yolk.

TheVoyajJe of H MS Chall

Siphonophorae I'l XV

ANTHEMODES ORDINATA

PLATE XVI.

Order PHYSONEOLE.

Family A&almid&

Lychnagalma vesicularia.

PLATE XVI.

Drawn by me from life in Ceylon, December 1881.

Lychnctgalma vesicularia, n. sp. (p. 253).

Fig. 1. The complete corm in a living state, quietly floating on the surface, with expanded
stem and tentacles. The biserial nectosome is composed of a small apical
pneumatophore {p), and ten pairs of opposite nectophores (n). The long
siphosome (the lower part of which is truncated) is densely covered with
bracts and bears numerous loose cormidia. The hydrostatic terminal ampulla?
of the tentilla are directed upwards.

Fig. 2. The same corm, half dead, in a highly contracted state, after the detachment of
most of the appendages ; slightly magnified, a, Trunk ; i, buds of nectophores ;
p, pneumatophore ; b, bracts ; s, siphons ; q, palpons ; t, tentacles.

Fig. 3. A portion of the siphosome ; slightly magnified, a, Trunk ; b, bracts ; sm,
siphons ; ss, suctorial disc of the mouth ; g, gonodendra.

Fig. 4. Pneumatophore. pp, Pigment-cap (mitra oeellaris) ; py, pylorus infundibuli ;
pq, radial pouches of the pericystic cavity ; pr, radial septa between them ;
i, buds of nectophores ; a, trunk.

Fig. 5. Lateral view of a nectophore (from the left side), np, Pedicle ; el, left radial
canal ; w, subumbrella.

Fig. 6. Dorsal view of a nectophore. v, Velum ; k, four cnidonodes on its basal insertion
(rudimentary tentacles).

Fig. 7. Lateral view of a bract (in profile), be, Bracteal canal.

Fig. 8. Dorsal view of a bract (from above), be, Bracteal canal.

Fig. 9. A single tentillum. ts, Pedicle; th, involucre; tk, ' cnidoband; to, hydrostatic
terminal ampulla ; x, oil-globule in its apex ; tc, corona of eight (contracted)
radial filaments around its base.

LYCHNAGALMA VESICULARIA.

PLATE XVII.

Order PHYSONECT^E.

Family Agalmida

Crystattodes vitrea.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.)— Hhllll.

PLATE XVII.

Drawn from life by me in Ceylon, in January 1882.

Crystallodes vitrea, n. sp. (p. 222).

Fig. 1. Lateral view of the complete corm (from the left side), whilst quietly
floating on the surface, with horizontal trunk. The pneumatophore
(p) is directed upwards. One series of nectophores (n) is dorsal,
the opposite ventral. Five cormidia depend in the ventral median
line of the siphosome, which is entirely covered with bracts (6),

Fig. 2. Dorsal view of the same corm. Characters as in fig. 1 ,

Fig. 3. Ventral view of the same corm. Characters as in fig. 1 ,

Fig. 4. A single cormidium. sm, Siphon ; sh, liver; sr, proboscis ; m, muscles ;
so, mouth ; t, tentacles ; q, palpons ; b, bracts ; h, androphores ; f,
gynophores, .......

Fig. 5. A single tentillum. ts, Pedicle ; th, involucre ; tk, cnidoband ; kg,
large basal cnidocysts ; km, small paliform cnidocysts ; tc, lateral
horns ; ta, terminal ampulla, .....

Figs. 6-13. Different views of nectophores, .

Fig. 6. Dorsal view of two opposite nectophores. a, Trunk (in transverse

section) ; cd, dorsal canal ; el, left canal ; ex, right canal.

Fig. 7. Apical view of a nectophore. np, Pedicle of insertion.

Fig. 8. Basal view of a nectophore. v, Velum.

Fig. 9. Oblique ventral view of a nectophore.

Fig. 10. Oblique dorsal view of a nectophore.

Fig. 11. Apical view of a young nectophore.

Fig. 12. Lateral view of a young nectophore. w, Subumbrella.

Fig. 13. Oblique lateral view of a nectophore.

Figs. 14-16. Different views of bracts. 6c, Bracteal canal,

Diarn.

2

2
2

20

200

4

TheYo

Sipho I x\*n.

CRYSTALLODES VITREA

PLATE XVIII.

Order PHYSONECTyE.

Families Apolemid/e et Agalmidj;.

Figs. 1-7. Dieymba diphyopsis.
Figs. 8-17. Agalma eschscholtzii.

PLATE XVIII.

Figs. 1-7. Dicymba diphyopsis (p. 210).

Fig. 1. The entire corm, drawn from life, with expanded trunk, and twelve fully developed ordinate
cormidia. p, Pneuuiatophore ; n, nectophores ; w, subumbrella ; v, velum ; a, axial trunk.

Fig. 2. A single cormidium. s, Siphon j sh, its four hepatic ridges ; sr, proboscis ; sb, basigaster ; /, tentacle ;
y, cyston ; q, palpons ; r, palpacles ; b, bracts ; h, androphores ; /, gynophores ; a, trunk of the corm.

Fig. 3. A female gonodendron.

Fig. 4. A single female gonophore. fu, Umbrella ; o, ovarium with a single egg, surrounded by a network
of spadicine canals (cy) ; utj, ocelli of the margin ; cr, radial canals.

Fig. 5. A male gonodendron.

Fig. 6. A single male gonophore. hu, Umbrella ; km, spermarium ; cr, radial canals.

Fig. 7. Transverse section through the trunk. at, Axial canal of the trunk ; d, entoderm ; m, longi-
tudinal muscles ; e, exoderm ; i, bud in the ventral median line ; ad, nerve in the dorsal median
line.

Figs. 8-17. Agahna eschsckoltzii, n. sp. (p. 226).

Fig. y. The entire corm, drawn from Hfe. The nectosome is composed of an apical pneumatophore (p) and
four pairs of nectophores (?i). The subspherical siphosome is densely covered with bracts (b) ; from
its axial cavity issue below a number of siphons (s) and tentacles, palpons (q) and palpacles (r).

Fig. 9. A single nectophore, from the dorsal side, w, Subumbrella ; uy, ocelli.

Fig. 10. A trilobate bract, from the dorsal side, be, Bracteal canal.

Fig. 11. A quiucpaelobate bract, from the dorsal side.

Fig. 12. A trilobate bract, in profile.

Fig. 13. A quinquelobate bract, in profile.

Fig. 14. A single tentilkun. fp, Pedicle; th, involucre; th; cnidoband ; fa, terminal ampulla; tc, paired
lateral horns.

Fig. 15. A female gonodendron. fu, Umbrella of the gynophores; o, egg; a, trunk.

Fig. 16. A single gynophore. fu, Umbrella ; cr, its four radial canals ; cc, circular canal ; cy, spadicine canals of
the manubrium (around the egg) ; o, ovule.

Fig. 17. A male gonodendron. a, Trunk; hu, umbrella of the androphores; hm, spermarium.

TMoyagi ofH^J.SI'Challcnger."

. In

f

1-7. DICYMBA DIPHYOPSIS. 8-17. AGALMA ESCHHOLTZII

PLATE XIX.

Order PHYSONECM

Family Discolabid^e.

Discolabe quadrigata.

(ZOOL. CHALL. EXP.— PART LXXVII.— 18S8.)— HMh.

PLATE XIX.

Figs. 1-4 were drawn by me from life in Ceylon, in December 1881.

Discolabe quadrigata, n. sp. (p. 263).

Fig. 1. The complete corm, living and floating quietly on the surface of the
sea. p, Pneumatophore ; n, nectophores ; q, palpons ; r, palpacles ;
s, siphons ; t, tentacles ; g, gonodendra, ....

Fig. 2. Lateral view of a nectophore, from the right side, np, Pedicle ; ex,
right radial canal ; cc, ring-canal, .....

Fig. 3. Dorsal view of a nectophore. cl, Left canal ; ex, right canal ;
no, ostium of the nectosac, .....

Fig. 4. Basal view of a nectophore, from the outside, np, Pedicle on the
ventral side ; cc, ring-canal, .....

Figs. 5-8. Different larval stages (Physonula). Compare pp. 261, 262.

Fig. 5. A young medusiform larva, with incipient tentacle (/). b, Umbrella (or

bract) • p, pneumatophore (pneumadenia of the umbrella) ; s, siphon ;

so, mouth.
Fig. 6. A somewhat older larva, with sessile cnidonodes on the tentacle (f).

Characters as in fig. 5. x, Cnidouode on the distal end of the pedicular

canal ; be, bracteal canal ; q, palpons.
Fig. 7. An older larva, with pediculate tentilla on the tentacle (t). Characters as

in figs. 5 and 6.
Fig. 8. Physonula with two opposite primary nectophores (n), similar to Dicyrnba

(PI. XVIII. fig. 1). The pedicle (am) of the single siphon (s) represents

the trunk of the incipient polygastric corm. Characters as in figs. 5-7.

Diam.

TheVoyage of HM.S.'Challenger

Siphonophoranl'l XIX

DISCOLABE Q.UADRIG ATA.

PLATE XX.

Order PHYSONEGML.

Family Discolabida
Discolabe quadrigata.

PLATE XX.

Discolabe quadrigata, n. sp. (p. 263).

Figs. 9-13. Different views of the vesicular trunk, after detachment of the necto-
phores, palpons, siphons, and tentacles, p, Pneumatophore ; pp, pigment-
cap (mitra ocellaris) ; pr, radial septa between the eight pouches of the
pericystic cavity ; an, spindle-shaped trunk of the nectosome ; np, con-
voluted longitudinal fold on its ventral median line, where the pedicles of
the nectophores have been attached ; in, buds of nectophores ; as, discoidal
trunk of the siphosome, spirally twisted in the form of a subcircular inflated
bag ; af, quadrangular facettes on the peripheral margin of the trunk of
the siphosome, each facette corresponding to the insertion of a large
palpon, and the small opening in its centre (cq) to the small canal which
connects the cavities of the palpon and of the vesicular trunk. Attached
to the inferior margin of each facette are two distylic clustered gono-
dendra ; a larger proximal female cluster (/), composed of very numerous
ovate gynophores ; and a smaller distal male cluster (h) with a single large
spindle-shaped gonopalpon (gp). The pedicles of the detached siphons are
visible in the basal view (fig. 12, sp).

Fig. 9. Apical view of the trunk (from above).
Fig. 10. Lateral view of the trunk (from the left side).
Fig. 11. Ventral view of the trunk (from before^.
Fig. 12. Basal view of the trunk (from below).

Fig. 13. Ventral view of a smaller trunk. A single siphon (s) and tentacle (t) have re-
mained in this younger specimen attached to the stem.

Fig. 14. A single tentillum. tp, Distal portion of the inflated pedicle ; th, vesicular
involucre ; ty, ocellus in its wall ; th, spiral cnidoband.

Fig. 15. Apical view of the nectosome, exhibiting the cruciform arrangement of the
four rows of nectophores (n) around the central pneumatocyst ( p).

Fig. 16. A single complete cormidium, in the usual natural position of its component
organs. q, Palpon (horizontal) ; af, facette of the trunk where the
proximal base of the palpon is inserted ; cp, canal of the palpon in the
centre of the facette ; r, palpacle ; gf, clustered female gonodendron ;
gh, smaller male gonodendron ; gq, its large gonopalpon ; fop, insertions of
pedicles of detached androphores ; s, siphon (vertical) ; so, its distal mouth ;
t, tentacle ; ts, tentilla ; hs, cnidosacs.

TheVqyageofHM S.'Challenger

SiphonophoraePl XX.

EHaecHandAQiltschDi

D ISCOLABE Q.U A DRIG ATA

PLATE XXL

Order PHYSONECT^E.

Families Circalid^e et Athokida

Figs. 1-4. Circalia stephanoma.
Figs. 5-8. Athoria larvalis.
Figs. 9-13. Larvae Physonectarum.

(ZOOL. CHALL. EXP. — FART LXXVII. — 1888.) — HhKh.

PLATE XXL
Figs. 1-4. Circalia stephanoma, n. sp. (p. 198).

Fig. 1. The entire nionogastric corm, drawn from life, ji, Pneumatophore ; pf, pneumatocyst ; pp, pigment-
cap ; pi, pneumatochone ; n, corona of eight nectophores ; v, velum ; gk, male gonodendron; gf,
female gonodendron ; q, palpons ; r, palpacles ; t, tentacle; s, siphon; sh, liver-ridges; sr, prohoscis ;
ss, suctorial mouth.

Fig. 2. Apical view of the half corm. Characters as in fig. 1.

Fig. 3. Basal view of the half corm. ss, Suctorial mouth ; h, androphores ; /, gynophores.

Fig. 4. Horizontal section through the pneumatophore. pf, Cavity of the pneumatocyst ; pq, radial pouches
of the pneumatophore ; jji; radial septa between the pouches.

Figs. 5-8. Athoria larvalis, n. sp. (p. 202).

Fig. 5. The entire monogastric corm, drawn from life, p, Pneumatophore ; b, corona of bracts ; q, palpons ;
r, palpacles ; t, tentacle ; s, siphon ; ss, suctorial disc of the mouth.

Fig. 6. Vertical frontal section through the axis of the corm (semi-diagrammatic), p, Pneumatophore;^?/,
pneumatocyst ; pe, pericystic cavity ; pi, pneumatochone ; at, cavity of the trunk ; b, bracts ; be,
bracteal canal ; bs, rudimentary nectosac of the bract ; «', its radial canals ; lc, cnidonodes on its
mouth; q, palpon; r, palpacle; /;, androphores; /, gynophores; t, tentacle; ts, tentilla; sb, basi-
gaster; sm, stomach ; sv, its hepatic villi ; sr, proboscis ; ss, suctorial mouth.

Fig. 7. A single bract, be, Bracteal canal ; bs, subumbrella ; k, cnidonodes on its mouth.

Fig. 8. A single tentillum. ts, Pedicle ; tk, spiral cnidoband ; //', terminal filament.

Figs. 9-13. Larvse Physonectarum (pp. 195, 200).
pig. 9. Larva with a single bract (b). p, Pneumatophore; s, siphon ; so, mouth ; t, tentacle ; i, buds.
Fig. 10. Larva with two opposite five-edged bracts (b). Characters as in fig. 9. bs, Nectosac.
Fig. 1 1. Larva with four cruciate trifid bracts (b) seen from the apex, p, Pneumatophore ; i, buds ; k, cnidonodes.
Fig. 12. Larva with a corona of five-edged bracts (l). Characters as in figs. 9, 10.
Fig. 13. Rudimentary tentillum. ts, Pedicle; tic, cnidosacs.

The Voyage of H.M.S."CMeii$i'".

Siphonophorae P1JCX1

1 1 CIRCALIA STEPHANOMA

ATHORIA LARVAL1S

PLATE HE.

( Jrder CYSTONECTvE.

Families Cystalid.e et Epibulice.

Figs. 1-5. Cystalia monogastrica.
Figs. 6-8. Epibulia ritteriana.

PLATE XXII.

The figures of this Plate were drawn by me from life in Ceylon, in December 1881 and January 1882.

Figs. 1-5. Cystalia monogastrica, n. sp. (p. 316).

Fig. 1. Larva of an early stage, near to the gastrula. The spindle-shaped body is composed of a small-
celled ciliated exoderm (e) and a large-celled entoderm (<!). The incipient pneumatophore (p) is a
simple invagination of the apical pole.

Fig. 2. Larva of a second stage. The medusiform body is divided by a transverse constriction into an apical
and a basal half ; the former includes the pneumatophore (containing an air-bubble), and is homo-
logous with the umbrella ; the latter includes the gastral cavity (sc), and is the primary siphon.
From the constriction arises a simple tentacle (t). The distal end of the siphon has a mouth-
opening (so), ps, Pneumatosac ; pf, pneumatocyst.

Fig. 3. Larva of a third stage, differing from the preceding (fig. 2) in the formation of a bud (palpon), which
arises from the ventral side of the transverse constriction (/), opposite to the dorsal tentacle (t).
Characters as in figs. 1, 2.

Fig. 4. Larva of a fourth stage. A corona of buds (palpons) arises from the base of the siphon below the
float. The tentacle (t) boars a series of simple filiform tentilla (As).

Fig. 5. A mature corm of Gystalia monogastrica, representing a single cormidium. p, Pneumatophore;/)/,
pneumatocyst filled with air; pi, pneumatochone ; q, palpons; sb, basigaster ; sh, hepatic villi of the
stomach ; sr, proboscis ; ss, mouth ; t, tentacle ; gd, monostylic gonodendron.

Figs. 6-8. Epibulia ritteriana, n. sp. (p. 335).

Fig. 6. A mature corm of Epibulia ritteriana. p, Pneumatophore (compare the sections in figs. 7 and 8);
q, palpons ; qo, ocelli ; s, siphons ; sh, hepatic villi ; ss, mouth ; t, tentacles ; ts, tentilla ; gd,
gonodendra.

Fig. 7. Vertical section through the axis of the pneumatophore. po, Apical ostium ; pu, pneumatocodon ; ps,
pneumatosaccus ; pp, pigment-cap (mitra ocellaris) ; pf, pneumatocyst ; py, pylorus infundibuli ;
pi, infundibulum (pneumatochone) ; pc, pericystic cavity ; pd, endocystic tapetum ; pv, hypocystic
villi ; at, cavity of the trunk.

Fig. 8. Horizontal section through the pneumatophore. Characters as in fig. 7.

TheVoyageofttM.S."Challcnger."

Siphonophorae Pl.XXD

1 5. CYSTALIA MONO G AST.R I CA . (i 8, EPIBULIA RITTERIANA

PLATE XXIII.

Order CYSTONECT^E.

Family Rhizophysida
Nectophysa ivyvillei.

(ZOOL. CHALL. EXP.— PART LXXVII. — 1 888. )— Hllllh.

PLATE XXIII.

The figures of this Plate were drawn by me from living specimens in the Canary Island Lanzerote,

December 26, 1866.

Nectophysa ivyvillei, n. sp. (p. 327).

Diam.

Fig.f 1. A complete corm, in the expanded state, quietly floating on the surface.
p, Pneumatophore ; po, its apical stigma ; pv, hypoeystic villi ; a,
trunk ; s, siphons ; t, tentacles ; ga, gonodendra, . . . nat. size

Fig. 2. A complete larger corm, in the expanded state, with twisted trunk,
reposing on the bottom of the glass vessel. The suctorial mouth-
discs of the lower siphons are attached to the wall of the vessel.
Characters as in fig. 1, . . . . . nat. size

Fig. 3. A complete corm (the same as fig. l) in the contracted state, with
shortened and thickened trunk, coiled up in a dexiotropic spiral. An
air-bubble (x) is being expelled through the apical stigma (po) of
the pneumatophore ; pf, pneumatocyst ; pp, pigment-cap (mitra
ocellaris) ; pv, hypoeystic villi, . . . . . x 4

Fig. 4. Uppermost portion of the fully contracted trunk. The pneumatocyst
(pf) is nearly evacuated and the greatest part of the gas expelled
through the apical stigma (po). The hypoeystic villi (pv) are
thrown into the vesicular inflated apical portion of the trunk (a) ;
i, buds; ga, gonodendra ; s, siphons, . . . x 10

Fig. 5. A single siphon, with its tentacle (t) attached to the trunk (at) ; ts,

tentilla, . . . . . . . x 20

Fig. 6. A small portion of a tentillum. kc, Cnidocysts ; tw, palpoblasts, . x 300

Fig. 7. A single cnidocyst with the included cnidofilament, . . . x 900

Fig. 8. A single branch of a gonodendron. gq, Gonopalpon ; h, androphores ;
hx, spadix ; hs, sperma; /, gynophore; fm, its rudimentary manu-
brium; uw, subumbrellar cavity, . . . . x 50

The \ "ova ■ a\

Will

N ECTO'PHYS A

WYV I LLEI

PLATE XX1Y.

Order CYSTONECTiE.

Familv Rhizophysid .e.

J

Cannophysa m urrayana.

PLATE XXIV.

The figures of this Plate were drawn by me from living specimens in the Canary Island Lanzerote,

January 7, 1867.

Cannophysa murrayana, n. sp. (p. 324).

Fig. 1. An adult corm, with large ripe gonodendra of a golden colour attached to the yellow
trunk near the base of the rose-coloured siphons. The cylindrical trunk is
twisted in a dexiotropic spiral. The apical pneumatocyst is rather expanded.
The animal reposes quietly on the bottom of the glass vessel.

Fig. 2. The same corm, in the highly Contracted state, seen from above, p, Pneumatocyst ;
g, gonodendron ; s, siphon.

Fig. 3. A young corm, without gonodendra, in the expanded state. The rose-coloiunl
siphons arise from the yellow trunk at equal distances, a, Trunk ; p, pneu-
matophore ; s, siphons ; t, tentacles.

Fig. 4. The pneumatophore. po, Apical stigma ; pp, pigment-cap (mitra ocellaris) ; pf,
pneumatocyst filled with gas ; pd, tapetum endocystale ; pv, hypocystic villi ;
i, buds ; s, siphons.

Fig. 5. Oblique apical view of the same pneumatophore. po, Apical stigma, open ; pp,
mitra ocellaris ; pm, radial fibres of the muscular dilatator ; pn, circular fibres
of the muscular sphincter ; pz, hypocystic villi ; p, pneumatocodou.

Fig. 6. A group of hypocystic villi. Each villus consists of a few gigantic exoderm
cells and a covering epithelium of numerous small ciliated entoderm cells (pz).

Fig. 7. Three greenish exoderm cells of the pneumadenia, taken from the endocystic
tapetum.

Fig. 8. A single tentacle, arising from the base of the siphon (s). ts, Tentilla; te, simple
terminal appendage of the tentacle (without tentilla) ; a. stem.

Fig. 9. A single tentillum. ts, Villi of the pedicle ; ta, terminal ampulla ; tf, its distal
appendage ; tc, lateral horns.

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CANNOPHYSA MURRAYANA.

PLATE XXV.

Order CYSTONECTtE.
Family Salacid^:.
Salacia polygastrica.

(ZOOL. UHALL. EXP. — PAKT LXXVII. — 1888.) — Hhhll.

PLATE XXV.

Salacia polygastrica, n. sp. (p. 331).

Diam.

Fig. 1. A complete corm. The large ovate pneumatophore exhibits the en-
closed pneumatocyst and the hypocystic villi. The long tubular
trunk bears a series of numerous ordinate polygastric cormidia,
separated by free naked internodes, . . . . x 4

Fig. 2. Transverse section through the pneumatophore in the equatorial plane.
pi, Pneumatochone (infundibulum pneumaticum) ; py, pylorus in-
fundibuli ; pv, hypocystic villi ; pu, pneumatocodon (umbrella
pneumatica), . . . . . . . x 8

Fig. 3. Apical view of the pneumatophore (from above), po, Central stigma,
(apical ostium) ; pm, radial muscles (dilatator stigmatis), round
which is seen the mitra ocellaris (corona of eight radial pigment-
lobes) ; pv, hypocystic villi, . . . . . x 8

Fig. 4. A single (polygastric and monoclinic) cormidium, attached to the stem.

s, Siphons ; so, suctorial disc ; t, tentacle ; g, gonodendron, . . x 8

Fig. 5. A single siphon with its tentacle (t) attached to the trunk, g,
Gonostyle ; sb, basigaster ; sm, stomach ; sv, hepatic villi ; sr,
proboscis ; so, mouth, . . . . . x 20

Fig. 6. A single (monostylic) gonodendron, attached to the stem (a) and
exhibiting the ramification of the gonostyle (gs). The majority
of the numerous branches and gonophores have been removed.
/, Gynophores ; h, androphores ; gq, gonopalpons, . . x 20

Fig. 7. A single branch of the (monostylic) gonodendron. Characters as in

fig. 6, . . . . . . . x 50

Siphonophorae I'l 7./.V

;

S ALAC I A POLYGASTR ICA.

PLATE XXVI.

Order GYSTONECTtE.

Family Physalidj;.

Figs. 1-3. Alophota giltschiana.
Figs. 4-8. Arethusa challengeri.

PLATE XXVI.

The figures of this Plate were painted by me from living specimens in the Canary Island Lanzerote,

December 1866.

Figs. 1 3. Alophota giltschiana, n. sp. (p. 348).

Diam.

Fig. 1. A young larva (Cystonula) 2 to 4 mm. in length. The complete body represents a single
medusome, the modified umbrella of which is the pneumatophore (pf), the manubrium is the
siphon (s). From the pedicle of the siphon (or the incipient trunk, a) arises a tentacle (t).
The inside of the siphon bears hepatic villi (so), and its terminal mouth forms a square
suctorial disc (ss). The apex of the float opens by a stigma (po), . . ■ . x 20

Fig. 2. An older larva 8 mm. in length. The trunk (a) of the small corm encloses an ovate pneu-
matosac (pf) in its apical half, and bears the primary siphon (or protosiphon, sv) on the
distal pole of the sub-horizontal main axis. From the middle third of its ventral side arise
three small cormidia, each of which is composed of a secondary siphon, a palpon, and a
tentacle ; po, apical stigma, . . . . . . . . x 8

Fig. 3. A mature corm of Alophota giltschiana, seen from the right side. The pneumatocyst (pf)
fills the greatest part of the vesicular trunk, po, The apical stigma (on the anterior end).
The basal (or posterior) end of the trunk bears the primary siphon (su) with a palpon and a
tentacle ; so, mouth of siphon. The ventral side of the trunk bears an ordinate series of five
cormidia, each composed of a secondary siphon (s), a palpon (to), a tentacle (t), and a
gonodendron (g), . . . . . . . . . . x 4

Figs. 4-8. Arethusa challenge?^, n. sp. (p. 349).

Fig. 4. Lateral view of a mature corm, from the right side. The oblongish pneumatosac (pf) fills
only two-thirds of the vesicular trunk, po, Apical stigma. The sterile protosiphon (su), at
the basal or distal pole of the horizontal axis, is separated by a group of small palpons
from the ventral series of fertile metasiphons ($) ; the larger of these bear on the right side
a rose-coloured gonodendron (g), . . . . . . . . x 2

Fig. 5. Lateral view of a larger corm, in a much contracted state, from the left side. The pneumatosac
(pf) strongly contracted, with an annular constriction, expels gas through the apical
stigma (po). The numerous tentacles are spirally coiled up, ... nat. size

Fig. 6. A single cormidium, isolated. The simple common pedicle (ap), arising from the ventral side
of the trunk, bears a large tentacle (t), with a basal ampulla (to), a clustered gonodendron
(g), and a contracted siphon with four segments ; sp, siphonal pedicle ; sb, basigaster, sv,
stomach with black hepatic villi; sr, proboscis; so, mouth, . . . . x 10

Fig. 7. A very young tentacle (t) with its basal ampulla (to), . . . • . x 40

Fig. N. A. single branch of a gonodendron. gs, Gonostyle ; q, gonopalpons ; //, androphores (male

medusomes) ;/, gynophore (female medusome), . . . . . . x 20

■fe •

-.„^->..

ALOPHOTA GILTSCHIANA.

PLATE XXVII.

Order CALYCONECTvE.

Family Monophyid^e.

Figs. 1-12. Cymbonectes huxleyi.
Figs. 13, 14. Monophyes princeps.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) — Hllllh.

PLATE XXVII.

Figs. 1-12 of this Plate were drawn by me from life in Ceylon, in December 1881.

Figs. 1-12. Cymbonectes huxleyi, n. sp. (p. 134).

Diam.

Fig. 1. The entire corni with expanded stem. From the hydroecial groove of the single nectophore
proceeds a long tubular stem, which bears eight or nine well-developed diclmic cormidia,
alternating males and females. The signification of the characters is the same as in
figs. 2-4, . . . . . . . . . . x 10

Fig. 2. Dorsal view of the nectophore. cs, Somatocyst ; co, oleocyst ; ex, right canal ; el, left canal ;

w, subumbrella ; nd, dorsal edge of the umbrella, . . . . x 10

Fig. 3. Ventral view of the nectophore. a, Apical part of the trunk ; nx, right wing, nl, left wing

of the ventral side of the exumbrella, protecting the hydroecial canal, . . x 10

Fig. 4. Horizontal transverse section through the middle part of the nectophore. w, Subumbrella ;
uw, its cavity ; ed, dorsal canal ; ex, right canal ; nd, dorsal edge of the exumbrella ;
nx, right ventral wing ; nl, left ventral wing ; ui, hydroecial canal ; a, trunk of the
siphosome, . . . . . . . . . x 10

Fig. 5. A single female cormidium. b, Bract ; be, phyllocyst ; co, oleocyst ; a, trunk ; s, siphon ;
sb, basigaster ; sm, stomach ; sr, proboscis ; s«, suctorial disc ; /, gynophore ; a; its radial
canals ; o, ovarium, . . . . . . . . x 50

Fig. 6. A single male cormidium. b, Bract ; be, phyllocyst ; co, oleocyst ; a, trunk ; s, siphon ;

t, tentacle ; /(, androphore ; hx, spadix ; lis, spermarium ; uo, ostium umbrellae, . x 50

Figi 7. Longitudinal section through a single siphon, in a highly contracted state, with the neigh-
bouring parts, be, Phyllocyst ; co, oleocyst ; /, tentacle ; ts, tentilla ; sb, basigaster ;
sm, stomach ; sr, proboscis ; so, mouth, . . . . . . . x 200

Fig. 8. A single tentillum. ts, Pedicle ; tk, cnidosac ; krj, large reniform lateral cnidocysts ; km,
small paliform median cnidocysts ; kp, small pyriform distal cnidocysts ; //, terminal
filament, .......... x 400

Figs. 9-12. Four different larval stages (Calyeonuld) of Cymbonectes huxleyi, arising from the
fertilized egg. Each larva is a single medusome, the manubrium of which (or the primary
siphon, s) has been protruded through the ventral fissure of the umbrella (or the primary
nectophore, n). e, Exoderm ; d, entoderm ; t, tentacle ; w, subumbrella • v, velum, . x 300

Figs. 13, 14. Monophyes princeps, n. sp. (p. 129).

Fig. 1 3. Lateral view of the nectophore, from the left side, cs, Somatocyst ; co, oleocyst ; cd, dorsal

canal ; el, left canal ; ex, right canal ; cv, ventral canal ; v, velum ; as, trunk, . . x 1 2

Fig. 14. Horizontal transverse section through the middle part of the nectophore. Characters as in

fig. 4, . . . x 12

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■ftiLS-thalltnto:

Siphonophorae PI XX\ il

ml

I VI. CYMBONECTES HUXLEYI

MONOPHYES PRINCEPS

PLATE XXVIII.

Order CALYCONECT^.

Family Monophyid.e.

Mitrophyes peltifera.

PLATE XXVIII.

Drawn from life by me in the Canary Island Lanzerote, in January 1867.

Mitrophyes peltifera, n. sp. (p. 131).

Diani.

Fig. 1. The complete corm, with expanded stem; the apical bract (b) and
the nectophore half in dorsal, half in lateral view (from the right
side), cv, Ventral canal ; cd, dorsal canal ; ex, right canal ; cb,
bracteal canal ; v, velum. The trunk of the dioecious siphosome
is fully expanded and bears numerous ordinate cormidia, . x 10

Fig. 2. The same corm, with contracted siphosome (a); the apical bract (b) is
reflected to show its pedicle and the union with the nectophore (n).
Characters as in fig. 1. ah, Cormidia, . . . x 10

Fig. 3. A single female cormidium. a, Trunk ; b, bract ; s, siphon ; sm,
stomach ; sr, proboscis ; so, mouth ; kc, cnidoeysts ; t, tentacle ;
f, gynophore ; o, eggs; v, velum; w, subumbrella, . . x 100

Fig. 4. A gynophore, with the included ovarium, isolated, o, Eggs ; uo, ostium

umbrellse ; v, velum, . . . . . x 150

Fig. 5. A single male cormidium. Characters as in fig. 3. h, Androphore ;

uo, ostium of the umbrella ; sb, basigaster, . . . x 100

Fig. 6. An androphore, with the included spermarium, isolated, hx, Axial

spadix ; lis, sperma ; uo, ostium umbrellae, . . x 150

Fig. 7. Apical portion of the trunk, with the connection of the apical bract (b)
and the nectophore. bp, Pedicle of the bract; cb, bracteal duct;
cs, somatoeyst ; ui, rudimentary hydroecium ; a, trunk ; i, buds of
cormidia ; en, nectophoral duct; cv, ventral canal; cd, dorsal canal;
ex, right canal ; cl, left canal. (Compare fig. 2), . x 40

Fig. 8. A single tentillum. kg, Large lateral cnidoeysts; m, small median
cnidoeysts ; kp, distal pyriform cnidoeysts ; tf, terminal filament,
spirally coiled up, . . . . . . . x 300

TheYqva<itMini.M.S lii.tli.n'.Mi

Sipkuiophorae PI. XXV11I

MITROPHYES PELTIFERA.

PLATE XXIX.

Order CALYCONECM.

Family Poiyphyi d^e.

Figs. 1-8. Polyphyes ungulata.
Figs. 9-14. Vogtia hollikeri.

(ZOOL. CHALL. EXP. — PART LXXVH. 1888.) — Hllhh.

*fc

■

PLATE XXIX.

Figs. 1-8. Polyphyes ungulata, n. sp. (p. 179).

Diam

Fig. 1. The complete corm. an, Trunk of the nectosome ; n, nectophores ;
s, siphons ; ss, suctorial mouth ; t, tentacles ; h, androphores ;
f, gynophores. (Lateral view of the nectosome), . . . x 4

Fig. 2. Lateral view of a nectophore (from the right side), np, Pedicle ; ce,

pallial canal ; w, subumbrella, . . . . . x 4

Fig. 3. Apical view of a nectophore. np, Pedicle ; nx, right wing, nl, left
wing, of the ventral groove ; ce, pallial canal ; cc, ring canal ; cv,
ventral canal ; cv", ventral sinus ; %v, subumbrella ; v, velum, . x 4

Fig. 4. Basal view of a nectophore. Characters as in fig. 3, . . . x 4

Fig. 5. Basal view of two united nectophores. an, Trunk with buds, . . x 4

Fig. 6. Dorsal view of a nectophore. . . . . . . x 4

Fig. 7. The isolated trunk of the corm, after detachment of the appendages.
an, Trunk of the nectosome ; in, its blastocrene (buds of nectophores) ;
as, trunk of the siphosome ; is, its blastocrene (buds of siphons) ;
x, free interval between the two blastocrenes (or points of vegetation) ;
en, canal of the nectophore ; ce, its pallial canal, . . . x 4

Fig. 8. A single tentillum. tp, Pedicle ; ts, cnidosac ; tk, cnidotsenia; kl, large

lateral cnidocysts; km, small median cnidocysts; tf, terminal filament, x 200

Figs. 9-14. Vogtia kollikeri, n. sp. (p. 182), . . x 5

Figs. 9-14. Different views of nectophores. ud, Dorsal face of the umbrella;

ux, right-hand face ; ul, left-hand face ; nx, right wing of the

ventral groove ; nl, left wing ; w, subumbrella ; v, velum ; ce,

pallial canal ; cc, ring-canal ; cv, ventral canal ; cv", ventral sinus.

Fig. 9. Lateral view (from the right side).

Fig. 10. Ohlique lateral view (half dorsal, half right side).

Fig. 11. Basal view of a young nectophore ; an, trunk with buds.

Fig. 1 2. Basal view of an adult nectophore.

Fig. 13. Ventral view.

Fig. 14. Dorsal view.

Yliv,l"rull[.\|\ili,illili"il

Siplionophorae Pl.XXIX.

1-8. POLYPHYES UNGULATA. 9 II-. VOGTIA KOLLIKERI

PLATE XXX.

Order CALYCONEOLE.

Family Desmophyid.e.

Desmophyes annectens.

PLATE XXX.

Drawn by me from life in Ceylon, in December 1881.

Desmophyes annectens, n. sp. (p. 170).

Diam.

Fig. I. The complete corm, with six nectophores and numerous diclinie

cormidia, males and females alternating, . . . . x 3

Fig. 2. Lateral view of a single female cormidium (from the right side).
b, Bract ; be, phyllocyst ; cv, ventral canal ; cd, dorsal canal ;
ex, right canal ; cl, left canal (see fig. 3) ; a, trunk ; s, siphon ;
sr, its proboscis ; t, tentacle ; run, special nectophore ; w, sub-
umbrella ; v, velum ; t, rudimentary tentacles ; uy, ocelli ; cc, ring-
canal ; cr, radial canals ; f, gynophore ; o, eggs, . . x 20

Fig. 3. Lateral view of a single male cormidium (from the left side) ; the
special nectophore, and the bunch of androphores (represented in
fig. 4), which fill up the ventral half of the bracteal cavity, have
been detached. Characters as in fig. 2. sb, Basigaster ; sh, hepatic
ridges in the stomach ; sr, proboscis ; ss, suctorial disc, . x 20

Fig. 4. A bunch of androphores (h) detached from the male cormidium, fig. 3.
u, Umbrella; cr, its four radial canals; cc, ring-canal ; hm, spermarium;
hx, spadix ; hs, sperma, . . . . . x 40

Fig. 5. A bunch of gynophores (f) detached from a female cormidium. u,
Umbrella ; cr, its four radial canals ; v, velum ; cc, ring-canal ;
o, eggs ; o1, germinal spot ; o2, germinal vesicle ; o3, germinal yolk, . x 40

Fig. 6. A special nectophore, detached from a male cormidium. w, Sub-
umbrella; v, velum; t, rudimentary tentacles; uy, ocelli ; cc, ring-
canal ; cr, radial canals ; ep, penduncular canal, . . x 40

Fig. 7. A small portion of the umbrella margin of the special nectophore, fig. 6,

more enlarged, cc, Bing-canal ; t, rudimentary tentacles ; uy, ocellus, x 100

Fig. 8. A single tentillum. tt, Pedicle; to, distal ampulla of the pedicle ; tk,
cnidosac ; kl, large lateral cnidocysts ; km, small median cnidocysts ;
hp, distal pyriform cnidocysts ; tf, terminal filament, . . x 300

ThcYoya<3eofH.M.S.'Challen<3cr

Siphonophorae PLX.XX.

DESMOPHYES ANNECTENS.

PLATE XXXI.

Order CALYCONECTiE.

Family Diphyid^e.

Praya galea.

(ZOOL. CHALL. ESP. — PAHT LXXVII. — 1888.) — Hllhh.

PLATE XXXI.

All the figures of this Plate were drawn by me from living specimens in the Canary Island Lauzerote,
February 17-20, 1867.

The characters have the same signification in all the figures : —

na. Apical nectophore.

nb. Basal nectophore.

ni. Hydrcecial groove enclosed between two

wings (ni, left whig ; nx, right wing).
np. Pedicle of the nectophore.
cp. Pedicular canal.
cs. Ascending pallial canal,
cs'. Descending pallial canal.

cv. Ventral canal.
cd. Dorsal canal.
ex. Right canal.
cl. Left canal.
cc. Ring-canal.
a. Trunk.
w. Rubumbrella.
v. Velum.

Praya galea, n. sp. (p. 146).

Diam.

Fig. 1. A complete living corm. The nectosome is composed of two large
opposite nectophores. The siphosome, in the perfectly expanded
state about two feet long, bears a series of forty to fifty cormidia,
separated by regular, equal, free internodes, . . . nat. size

Fig. 2. The two nectophores, seen in their natural junction, from the dorsal
side of the first (smaller) bell.

Fig. 3. The two nectophores, seen in their natural junction, from above (from
the apex). For "no" read " nb."

Figs. 4a, 4b. The two nectophores, in the same view as in fig. 3, but separated
one from the other. The two lateral wings (nx right, nl left), which
arise from the ventral side of each bell, include an open hydrcecial
groove (ni), and in the median ventral line of this latter arises the
pedicle of the nectophore (np).

Fig. 5. The first or apical nectophore, in lateral view (from the left side).

Fig. 6. The second or basal nectophore, in lateral view (from the right side).

Fig. 7. The second or basal nectophore, in ventral view (from the axial side).
The open hydrcecial groove is visible between the two ventral wings
of the bell (nx right, nl left wing).

TieVovaSe of II M S "Challenger

Siphonophorae I'l XXXI.

Itscl e

1 btho.4r.

PRAYA GALEA.

PLATE XXXII.

Order CALYCONECT^.

Family Diphyid^e.

Eudoxella galea.
(Monogastric generation of Praya galea.)

PLATE XXXII.

The figures of this Plate were drawn by rue from living specimens, in the Canary Island Lanzerote, February
17-20, 1867, except the bract, fig. 9, and the tentillum, fig. 14, which were found in a bottle in the Challenger
collection from Station 352.

Eudoxella galea, n. sp. (pp. 108, 148).

(Monogastric generation of Praya galea, PI. XXXI.)

Fig. 8. A single cormidium or eudoxome, sessile on the stem (a), composed of two medu-
somes or medusoid persons. The sterile medusome is composed of a helmet-
shaped or reniform bract (b), a siphon (s), and a tentacle (t). The fertile
medusome is a male gonophore (h), attached to the ventral side of the siphon
(s). The latter exhibits eight yellow hepatic ridges (sh) in the wall of its
stomach. The mouth (so) is closed. The bract (b) exhibits the four radial
canals of a medusome-umbrella, bilaterally developed, dorsal (cd), ventral (cv),
right (ex), and left (el). They are connected by the bracteal canal (ea) with
the stem (a). The long tentacle (t) is articulated and beset with numerous
tentilla.

Fig. 9. A single bract, with its four radial canals. Characters as in fig. 8 ; w, subumbrella.

Fig. 10. A female gonophore. The ovarium (f) is suspended in the apex of the sub-
umbrella (w). The bilateral umbrella exhibits a very large dorsal wing (nd)
and a smaller ventral wing (nv) ; v, velum.

Fig. 11. A siphon, doubly invaginated. The basigaster (sb) is strongly expanded and
has taken into it the retracted stomach (sh) ; the cavity of the latter again
contains the basal part of the invaginated proboscis (sr). The mouth (so)
is closed.

Fig. 12. A tentillum, seen from the convex dorsal side, km, Small median cnidocysts ;
kl, large lateral cnidocysts ; kp', kp", pyriform distal cnidocysts ; ts, pedicle ;
tf, terminal filament.

Fig, 13. A tentillum seen from the left side. Characters as in fig. 12.

Fig. 14. A tentillum, strongly contracted, from the right side. Characters as in fig. 12.

Fig. 15. The first or apical nectophore of a young corm, with a bunch of numerous buds (i).

rhe Voyage of H MS Tim!:

Siphonophorae I 'I XXXII

PRAYA GALEA.

PLATE XXXIII.

Order CALYCONECT.E.
Family Dip hyid.k.
Diphyopsis comjwessa.

(ZOOL. CHAI.L. EXP.— PAKT LXXVII.— 1888.)— Hhbh.

PLATE XXXIII.

The figures of this Plate were drawn by me from living specimens in the Canary Island
Lanzerote, December 28-30, 1866.

Diphyopsis compressa, u. sp. (p. 153).

Fig. 1 . A complete living corm, with expanded siphosonie. The first (apical)
nectophore is seen from its left side, the second (basal) from its
right side, cs, Somatocyst of the superior or proximal nectophore ;
cp, coryphal canal; w, subumbrella ; ni, hydrcecium ; ub, ventral
face of the umbrella ; np, pedicle of the inferior or distal
nectophore ; nl, its overlapping left wing ; nd, dorsal edge,

Fig. 2. The two nectophores, united, seen from the ventral side of the first.
cs, Somatocyst ; cp, coryphal canal ; iv, subumbrella ; nf, hydroecial
canal (infundibular furrow) ; nf1, its superior fissure ; nf 3, its inferior
fissure ; ni, hydrcecium of the first nectophore ; a, the included stem,

Fig. 3. The two nectophores, united, seen from the dorsal side of the first.
Characters as in fig. 2. The second nectophore exhibits distinctly
the left mantle-lobe of its umbrella (nl) overlapping the inferior
part of the hydroecial canal, .....

Fig. 4. The basal (distal or second) nectophore, seen from its right side.
np, Pedicle, with the apical canal (cp) ; nf1, superior, and nf2,
inferior fissure of the hydroecial canal ; w, subumbrella ; nd, odd
dorsal tooth ; nx-n6, three pairs of basal teeth, two of which
(nx-n*) surround the ostium of the umbrella,

Fig. 5. Apical part of the same nectophore, seen from its ventral side,
exhibiting the bridge (ub) between the two fissures of the
hydroecial canal (nf1, nf2), and the overlapping left mantle-
lobe (nl), ........

Fig. 6. Basal ostium of the apical (proximal or first) nectophore, seen from
below; v, velum; nd, odd dorsal tooth; n\ left, n2, right, lateral
teeth ; ri\ left, n*, right, ventral teeth ; cr, ring-canal,

Fig. 7. Basal part of the same nectophore, seen from its dorsal side. Characters
as in fig. 6, .......

Fig. 8. Basal view of the same nectophore, exhibiting the rectangular mouth
of the hydrcecium or the infundibular cavity, in which is hidden
the contracted siphosome (a). Characters as in fig. 6.

Diam.

H '

Siphonophorae Pl.XXXQI

DIPHYOPSIS COMPRESSA

PLATE XXXIV.

Order CALYCONECLE.

Family D i p h y i i> m.

Erssea compressa.
(Monogastric generation of Diphyopsis compressa.)

PLATE XXXIV.
Erssea coinvpressa, n. sp. (p. 123).

(Monogastric generation or free Eudoxia of Diphyopsis compressa, PL XXXIII.)

Fig. 9. A sessile young cormidium (or an immature Erssea) attached to the stem (a) of Diphyopsis compressa.
The cormidium is composed of two sterile medusomes, the first consisting of the bract (b), the
siphon (s), and the tentacle (t) ; the second representing a " special nectophore " (mi) ; er, radial
canals of the latter ; so, mouth of the siphon ; sb, basigaster ; es, phyllocyst ; co, oleocyst.

Fig. 10. A somewhat older cormidium than that shown in fig. 9, with larger nectophore (un) and smaller bract (l)
detached from the stem. Characters as in fig. 9 ; w, subumbrella of the nectophore ; v, its velum ;
un, ostium of the umbrella (u). The bract (b) of this specimen is rudimentary, and its apical
cucullate part (with the phyllocyst) is cut off; tk, cnidosacs of the tentacle.

Fig. 11. A mature and fully developed male Erssea, detached from the stem of Diphyopsis compressa, and
swimming freely. The cormidium is composed of four persons, two sterile medusomes and two male
gonophores (h). The first sterile medusome consists of a bract (b), a siphon (s), and a tentacle (/).
The second sterile medusome is represented by a large " special nectophore " (nn). bs, Superior,
cucullate part of the bract, with the phyllocyst (cs) and the oleocyst (cu) ; bz, inferior, mantle-
shaped or funnel-shaped, part of the bract, with four basal lobes; st>, mouth of the siphon; sb, basi-
gaster; //.', cnidosacs of the tentacle (t) ; lu; cavity of the spadix ; Inn, spermarium.

Fig. 12. An isolated ripe androphore. Inn, Spermarium ; hx, cavity of the spadix ; u, umbrella; un, its ostium.

Fig. 13. An isolated ripe gynophore. The manubrium (jm) is filled with large ovules. o\ Nucleolus; </-,
nucleus ; o3, protoplasm of the ovule ; fp, pedicle ; w, subumbrella ; u, umbrella ; un, its ostium.

Fig. 14. An older gynophore, the manubrium (Jm) of which contains only four large ovules, cc, Circular
canal which connects the four radial canals (cr) ; fp, pedicle of the gonophore ; cp, peduncular canal.
The other characters as in fig. 13.

Fig. 15. A portion of a radial canal (cr) and of the ring-muscles of the subumbrella (//•) of a gonophore.

Figs. 16, 17. Denticulate edges of the umbrella of a gonophore.

Fig. 18. A single tentillum, highly magnified, ts, Pedicle ; //, elastic ligament of the cnidosac ; kg, large lateral
cnidocysts ; km, small median cnidocysts ; kp, distal pyriform cnidocysts ; tf, terminal filament.

TheVqyage ofHMS Chall

lophorae I 'I XKX1V

DIPHYOPSIS COMPRESSA.

PLATE XXXV.

Order CALYCONECTjE.

Family Diphyidj;.

Abyla carina.

(ZOOL. CHALL. EXP. — PART LXXVII. 1888.) — Hllllh.

PLATE XXXV.

Drawn from life by me in the Canary Island Lanzerote, February 11, 1867.
The signification of the characters is the same in all the figures : —

nd. Dorsal edge of the nectophore.

nx. Eight wing.

nl. Left wing.

ud. Dorsal face.

uv. Ventral face.

ut. Transverse frontal crest.

uo. Ostium of the umbrella.

ui. Hydrcecium.

w. Subumbrella (Nectosac).

cs. Somatocyst (Acrocyst).
cd. Dorsal canal.
cv. Ventral canal.
ex. Right canal.
cl. Left canal.

nq. Articular condyle of the second nectophore.
as. Trunk of the siphosome.
v. Velum.

Abyla carina, n. sp. (p. 156).

Diam.

Fig. 1. The complete living corm, in its natural position, floating with
subhorizontal main axis on the level of the sea. A bunch of
tentacles issues by the basal opening of the hydrcecial canal. The
first and smaller (apical) nectophore is seen from the right side, the
second and larger (basal) nectophore from the left side, . . x 3

Fig. 2. The same corm, in the same natural position, seen from the apical face, x 3

Figs. 3-7. Different views of the first (proximal or apical) nectophore, . . x 6

Fig. 3. Apical view of the first nectophore ; the nectosac (w1) appears through

its dorsal apical facette. (For " cb " read " cl.")
Fig. 4. Basal view of the first nectophore ; in the ventral half of the base is visible

the opening of the hydroecium (ui), including the siphosome (as) ; in the

dorsal half the ostium of the nectosac (to1).
Fig. 5. Lateral view of the first nectophore, from the right side, w1, Nectosac ; ui,

hydroecium ; cs, somatocyst.
Fig. 6. Ventral view of the first nectophore, with the somatocyst (cs).
Fig. 7. Dorsal view of the first nectophore, with the nectosac {to1).

Figs. 8-11. Different views of the second (distal or basal) nectophore, . . x 4

Fig. 8. Ventral view of the second nectophore, with the siphosome (as) enclosed

in the hydrcecial canal.
Fig. 9. Lateral view of the second nectophore, from the left side, to2, Nectosac.
Fig. 10. Lateral view of the basal part of the second nectophore, from the right

side.
Fig. 11. Basal view of the second nectophore, from below, with the five teeth

surrounding the basal ostium.

hcVova&c 'il II M S Challen^i'i

Siphonophorae I 'I WW

.

ABYLA CARI NA

PLATE XXXVI.

Order CALYCONECTiE.

Family Diphyid.e.

Amphiroa carina.
(Monogastric generation of Abyla carina.)

PLATE XXXVI.

The signification of the characters is the same in all the figures :--

b. Bract.
be. Phyllocyst.

ex. Bight canal of the phyllocyst.
cl. Left canal of the phyllocyst.
cp. Coryphal canal.
ua. Apical face of the bract.
ud. Dorsal face of the bract.
s. Siphon.
so. Its mouth.

t. Tentacle.

h. Androphore.
lis. Spermarium.

/. Gynophore.
fo. Ovarium.

w. Subumbrella.

ny. Asymmetrical ventral wing of the gonophore.
nz. Dentate asymmetrical (external) dorsal wing of
the gonophore.

Amphiroa carina, n. sp. (p. 114).
(Monogastric generation or free Eudoxia of Abyla carina, PI. XXXV.)

l)iam.

Fig. 12. Lateral view of a complete immature Eudoxia, attached to the stem
of Abyla, from the right side. The monogastric corm is composed
of two medusomes, a male gonophore (w) and a sterile person (with
a bract, a siphon, and a tentacle), . . . . . x 1 0

Fig. 13. Lateral view of a similar immature Eudoxia, attached to the stem,

from the left side, . . . . . . x 8

Fig. 14. Ventral view of a mature Eudoxia, with a single female gonophore, . x 6

Fig. 15. Dorsal view of the same Eudoxia, . . . . x 6

Fig. 16. Apical view of the same Eudoxia (from above), . . . x 6

Fig. 17. Basal view of the same Eudoxia (from below), . . . x 6

Fig. 18. Lateral view of a monoclinic Eudoxia, from the left side, with a larger

androphore and a smaller gynophore, . . . . x 6

Fig. 19. Ventral view of a monoclinic Eudoxia, . . . . x 6

Fig. 20. Apical view of an isolated bract (from above), . . . x 6

Fig. 21. Ventral view of a sterile medusome (with bract, siphon, and tentacle), x 6

Figs. 22-25. Different views of gynophores, exhibiting the peculiar asymmetrical
development of the pentagonal umbrella (compare p. 115). In fig.
22, for "fs " read "fo," . . . . . . x (5

Fig. 26. A single tentillum, much enlarged, tp, Pedicle ; tk, cnidosac ; kg, large,
lateral, ensiform cnidocysts; km, small, median, paliform cnidocysts ;
kp, small, distal, pyriform cnidocysts ; tf, terminal filament.

The Voyage ofH M S Challenge!

Siphonophorae PI.. XXXVI.

ABYLA CARINA (AMPHIROA)

PLATE XXXYII.

Order CALYCONECTiE.

Family Diphyid.e.

Bassia obeliscus.

(ZOOL CHALL. EXP. — PART LXXVII. 1888.) — Hllllll.

PLATE XXXVII.

Drawn by me from living specimens in the Canary Island Lanzerote, in February 1867.
The signification of the characters is the same in all the figures : —

u. Angles of the nectophores.
if". Ostium of the iiectosac.
ml. Dorsal face of the nectophore.
w. Ventral face of the nectophore.
u>. H ydroecium.

v. Velum.
uk. Overlapping wing (Valvula hydroecii).
use. Left face of the apical nectophore.

Iff. Subunibrella.

nk. Coryphal edge of the umbrella.

cs. Somatocyst.

cd. Dorsal canal.

cv. Ventral canal.

ex. Right canal.

cl. Left canal.

■ ■•'. Ring-canal.

a. Trunk of the siphosome.

i. Buds of cormidia.

Fig.

Fig. 2

K,.,-

Fig.

Figs.

Fig.

Fig.

Fig.

Bassia obeliscus, n. sp. (p. 160).

Lateral view of the complete corm. The main axis of the smaller
(apical) nectophore is nearly horizontal, and perpendicular to the
vertical main axis of the larger (distal) nectophore ; the former is
seen from the left side, the latter from the right side. The sipho-
some, arising from the apex of the hydrcecium in the apical necto-
phore, passes through the funnel-canal of the distal nectophore and
projects freely through its basal aperture, ....

Lateral view of the complete corm, from the opposite side. The first
nectophore is seen from the right side, the second from the left side,

3. Ventral view of the complete corm. The smaller (proximal) necto-

phore is seen from its basal side, the larger (distal) nectophore from
its ventral side, .......

4. Oblique view of the complete corm. The smaller (proximal) necto-

phore is seen from the apical edge (nk), the larger (distal) nectophore
half from the left, half from the dorsal side,
. Different views of the first (proximal or apical) nectophore, .

Fig. 5. Ventral view of the first nectophore. The somatocyst (cs) is visible in

the tipper half, the hydrcecium (ui) with the siphosome (i) in the

lower half.
Fig. 6. Dorsal view of the first nectophore. The somatocyst (cs) is visible in

the upper half, the nectosac (w) in the lower half.
Fig. 7. Apical view of the first nectophore. cs, Somatocyst.
Fig. 8. Basal view of the first nectophore. wo, Aperture of the nectosac ;

o, velum.

Basal view of the second (distal or basal) nectophore. The nectosac
with its small circular aperture, the velum (v), and the four radial
canals are visible in the left-hand (dorsal) half of the figure ; the
opening of the funnel-canal (ui) and the included siphosome (a) in
the right-hand (ventral) half. (For "n" read "cc"),

10. Apical portion of the second nectophore, exhibiting the coryphal

apophysis or the articular condyle, through the opening of which
the siphosome (a) enters into the hydrcecial canal (ui),

11. Apical nectophore of a variety (?), or another species (?),

Diam.

5-8

9.

x 8
x 6

x 6

x 6

x 8

x 8

x 8
x 8

TheVoyaft of H.M.S.'Challengm

Siphonophorat PI. XXX VII.

la

jiltsch Jena

BASSIA OBELISCUS

PLATE XXXVIII.

Order CALYCONECTtE.

Family Diphyid,e.

Sphenoides obelise ns.
( Monogastric generation of Bassia obeliscus.)

PLATE XXXVIII.

Sphenoides obeliscus, n. sp. (p. 116).

(Monogastric generation or free Eudoxia of Bassia obeliscus, PI. XXXVII.)

Fig. 12. A complete Eudoxia, attached to the stem (a) of the polygastric generation,
Bassia obeliscus, seen from the left side. The bilateral bract (u) is beset
with scattered groups of cnidocysts, and exhibits twelve prominent pyra-
midal teeth (characters n^-u12 as in fig. 13). Its large phyllocyst contains
an apical oleocyst (co). The siphon (s) is placed between the dorsal tentacle
(t) and the ventral male gonophore (h). The numerous tentilla (tk) are
partly expanded (below), partly coiled up (above).

Fig. 13. Bract of a young sessile Eudoxia, attached to the stem (a), seen from the right
side. The twelve prominent three-sided pyramidal teeth have denticulate
edges and the following names : — u1, odd ventral apical tooth ; ir, u?, ventro-
lateral apical teeth ; u4, uh, ventro-lateral basal teeth ; un, u', dorso-lateral
basal teeth ; uB, odd dorsal basal tooth ; u9, odd dorsal cristal tooth ; uw, un,
dorso-lateral teeth ; u1'2, odd dorsal apical tooth, bh, Cavity of the bract ; %v,
its subumbrellar wall ; be, phyllocyst ; cd, its basal caecum (dorsal canal) ; co,
oleocyst.

Fig. 14. Bract of an adult free Eudoxia, seen from the right side. Characters as in
figs. 12 and 13.

Fig. 15. An isolated female gonophore. cp, Peduncular canal; gp, pedicle of the
umbrella ; o, ovarium ; w, subumbrella ; cr, radial canals ; cc, circular canal.

Fig. 16. A single tentillum. ts, Pedicle; kg, large basal cnidocysts; km, small
median cnidocysts ; kp, pyriform distal cnidocysts ; if, terminal filament.

fheVoyage of H.M.S Thalle

Siphonophorac PI H

BASSIA OBELISCUS (SPHENOIDES)

PLATE XXXIX.

Order CALYCONECT^E.

Family Diphyid^;.
Calpe gegenbauri.

(ZOOL. CHALL. EXP. — PART LXXVII. — 1888.) — HIlllll.

PLATE XXXIX.

Drawn from life by me in the Canary Island Lanzerote, February 1867.
The signification of the characters is the same in all the figures : —

ud. Dorsal face of the nectophore.
n n. Its ventral face.
tin. Its ostium.
ni. Infundibiilum.

/•: Subnmbrella.

r. Velum.
cs. Somatooyst.
co. Oleocyst.
,il. Dorsal canal.
cv. Ventral canal.

ex. Right canal.

cl. Left canal.

cc. Circular ring-canal.

ni-. Coryiihal edge of the umbrella.

nd. Dorsal edge of the umbrella.

re1, n*. Left edges.

re2, n*. Right edges.

a r. Right wing of the hydroecial canal.

ni. Left wing of the hydroecial canal.

as. Trunk of the siphosome.

Calpe gegenbauri, n. sp. (p. 164).

Figs. 1-4. The entire corra, with the two neetophores in their natural junction.

and the enclosed siphosome, seen from four different sides,

Fig. 1. Ventral view of the second, right lateral view of the first nectophore.

Fig. 2. Dorsal view of the second, left lateral view of the first nectophore.

Fig. 3. Eight lateral view of the second, oblique basal view of the first necto-
phore.

Fig. 4. Left lateral view of the second, oblique apical view of the first necto-
phore.

Figs. 5-8. The first (proximal or apical) nectophore alone, seen from four

different sides, .......

Fig. 5. Apical view of the first nectophore. The nectosac (w) shines through
the dorsal, the somatocyst (cs) through the ventral half.

Fig. 6. Dorsal view of the first nectophore, with the nectosac (vi) shining
through.

Fig. 7. Ventral view of the first nectophore ; the somatocyst (cs) is visible in
the upper half ; the hydrceciurn and the included siphosome (as) in
the lower half.

Fig. 8. Lateral view of the first nectophore, from the left side, w, Nectosac ;
cs, somatocyst; as, siphosome.

Fig. 9. The uppermost part of the second (distal or basal) nectophore, with
the upper opening of the hydroecial canal (ui), seen from the
ventral side, .......

Fig. 10. The same, seen from above, from the apical side,

Fig. 11. Horizontal transverse section of the second nectophore. nh, Its
swimming cavity; as, siphosome, .....

Fig. 12. Basal view of the second nectophore, from below, uo, Ostium of the
nectosac ; v, velum ; ui, basal opening of the hydroecial canal,

Diam.
6

x

X

12

12
12

i \\.\i.\

CALPE GEGENBAURI

•■■

PLATE XL.

Order CALYCONECT^.

Family Diphyid*.

Aglaisma gegenbauri.
(Monogastric generation of Calpe gegenbauri.)

PLATE XL.

Aglaisma gegenbauri, n. sp. (p. 119).
(Monogastric generation or free Eudoxia of Calpe gegenbauri, PI XXXIX.)

Diam.

Fig. 13. Lateral view of a diclinic (female) cormidium, from the right side
(and somewhat from behind), ua, Apical face of the umbrella ;
ud, dorsal face ; ux, right face ; ui, subumbrella (funnel or
bracteal cavity); be, phyllocyst ; co, oleocyst ; cv, ventral canal;
cd, dorsal canal ; ex, right canal ; cl, left canal ; s, siphon ; ss,
suctorial disc of the mouth ; t, tentacle ; f\ gynophore ; fm,
ovarium, . . . . . . . x 100

Fig. 14. Lateral view of a hermaphrodite (monoclinic) cormidium, from the
left side, and somewhat from before. Characters as in fig. 13 ;
uv, ventral face ; id, left face. At the right hand of the siphon
(s) is placed the larger androphore (Ii), at the left hand the smaller
gynophore (./*),. . . . . . x 100

Fig. 15. Basal view of the bract (from below), cd, Dorsal canal; ex, right

canal ; cl, left canal, . . . . . x 50

Fig. 16. Apical view of the bract (from above). Characters as in fig. 15 ; co,

oleocyst, . . . . . . . x 50

Fig. 17. Oblique dorsal view of the bract (somewhat from above and left

hand). Characters as in figs. 15, 16 ; cv, ventral canal, . x 50

Fig. IS. Oblique ventral view of the bract (somewhat from above, and right

hand). Characters as in figs. 15-17, . . . x 50

Fig. 19. A single tentillum, in a highly contracted state, much enlarged, tp,
Pedicle ; kg, large lateral cnidocysts ; km, small median cnido-
cysts ; tf, terminal filament, spirally coiled up, . . . x 300

Fig. 20. A single tentillum, in a highly expanded state, much enlarged, tp,
Pedicle ; tl, elastic ligament (angle-band) ; tk, cnidobattery ; tf
terminal filament, . . . . . . x 300

1 lie Voyage ol II M S Challenge!

SiphonophoraePl XL

CALPE GEGENBAURI IAGLAISMA

PLATE XLL

Order CALYCONEOLE.

Family M onophyid^.

Cymba crystallus.

(ZOOL. CHALL. EXP. — PART LXXV1I. — 1888.) — Hhhll.

PLATE XLI.

Drawn by me from living specimens in the Canary Island Lanzerote, February 1867.
The signification of the characters is the same in all the figures : —

cs. Somatocyst.
co. Oleocyst.
ui. Hydrcecium.
o. Trunk of the siphosome.

i. Buds.

v. Velum.
IB. Subumbrella.

cd. Dorsal canal.
cv. Ventral canal.
ex. Right canal,
cl. Left canal.
cc. Circular ring-canal.

For the other characters, compare the special
description, pp. 139, 140.

Fig. 2.

Fig. 3

Cymba crystallus, n. sp. (p. 138).

Fig. 1. Basal view of the complete corm (from below). The quinquedentate
mouth of the nectosac (no) is visible in the centre of the figure, and
beyond it the quadridentate aperture of the hydrcecium (ui) ; in the
latter is hidden the retracted siphosome (a),
Apical view of the complete corm (from above). The superior or
proximal half of the nectophore is visible, divided by four serrate,
cruciate, perradial edges into four nearly equal quadrants. In the
middle of each quadrant descends an interradial apophysis. The
apex of the nectosac (w) appears in the centre of the figure through
the upper (dorsal) half of the nectophore, the apex of the hydrcecium
(ui) through its lower (ventral) half, ....

Dorsal view of the nectophore, with its subumbrellar nectosac (w),

Fig. 4. Ventral view of the complete corm (anterior side). The hydrcecium
with its basal mouth (ui) and the included siphosome, above it the
somatocyst (cs), and at its apex the oleocyst (co), appear through the
pentagonal ventral face of the nectophore. This is surrounded by
four interradial faces, two smaller apici-lateral (ua" right, uaf left)
and two larger basi-lateral (ux right, ul left),
Lateral view of the complete corm, from the left side. The nectosac
with its mouth (uo) appears through the dorsal half of the necto-
phore, the hydrcecium with the included siphosome (i) through the
ventral half, above it the somatocyst (cs) and the oleocyst (co),

Fig. 6. The nectosac (iv) and the hydrcecium (ui) in lateral view, from the
right side. The retracted siphosome (i) is included in the hydrce-
cium, above it the somatocyst (cs), and at its apex the oleocyst (co),
The mouth of the nectosac (with five teeth), and beyond it the mouth
of the hydrcecium (ui) with the included siphosome (a). Basal
view of the central portion of the nectophore,

Fig. 8. Lateral view of the mouth of the nectophore (from the right side),

Fig. 5

Fig. 7.

Diam .

x 8

x 8
x 4

x 8

x 8

x 16

x 16
x 16

CYMBA CRYSTALLUS

PLATE XLII.

Order CALYCONECTiE.

Family Moxophyida

Ouboicles crystallus.
(Monogastric generation of Cymba crystallus.)

PLATE XLII.

Drawn by me from living specimens in the Canary Island Lanzerote, in February 1867
Figs. 9-14 are eight times enlarged, figs. 15-17 more highly magnified.
The signification of the characters is the same in all the figures : —

b. Bract (cuboidal hydrophyllium).
ua. Its apical face.
ud. Dorsal face.
uv. Ventral face.
ux. Right face.
vl. Left face.

id. Funnel-cavity (suburnbrella of the bract).
cs. Phyllocyst.
co. Oleocyst.

s. Siphon.

sb. Basigaster.
so. Its mouth.

t. Tentacle.
k. Cnidosac.
h. Androphore.
hm. Spermarium.

o. Ovary.

v. Velum.

w. Suburnbrella.

Cuboicles crystallus, n. sp. (p. 112).

(Monogastric generation or free Eudoxia of Cymba crystallus, PI. XLI.)

Fig. 9. Dipersonal corm, in lateral view, from the right side. The infundibulum (ui) (or the subumbrellar
cavity of the cuboidal bract) includes the siphon (s) with its tentacle (t), and on its ventral side a
male gonophore (h).

Fig. 10. Tripersonal corm, in dorsal view. Two male gonophores are placed in the ventral half of the
bracteal cavity (ui), whilst its dorsal half is occupied by the single siphon and its dorsal
tentacle. The phyllocyst exhibits its two pyriform lateral lobes (cs' right, cs" left), and above
them the yellow oleocyst (co).

Fig. 11. Dipersonal corm, in oblique lateral view (from the left and somewhat from the dorsal side). A large
male gonophore (/;) occupies the bracteal cavity (ui) on the ventral side of the siphon (s).

Fig. 12. Dipersonal corm, in dorsal view. The siphon (s) occupies the posterior, the gonophore (li) the
anterior part of the bracteal cavity (ui). Above this lies the phyllocyst with its two lateral lobes
(cs" right, cs' left), and above them the oleocyst (co).

Fig. 13. Tripersonal corm, in basal view. Two male gonophores (h and h') are visible beyond the siphon (s).

Fig. 14. Tripersonal corm, in apical view. The two Idbes of the phyllocyst (cs" right, cs' left) are visible,
and between them the apical oleocyst (co).

Fig. 15. The oleocyst (co) of an older Eudoxia, with an apical accumulation of entoderm-cells (cs'"). The
direction of the circulation of the fluid in the median part of the sornatoeyst is indicated by small
arrows.

Fig. 16. A single tentillum. ts, Pedicle; lg, large lateral cnidocysts; km, small median cnidocysts; tf,
terminal filament.

Fig. 1 7. A single female gonophore. The radial canals (cr) appear elegantly pinnulate. o, Ovarium ;
v, velum ; iv, suburnbrella ; cp, peduncular canal ; cc, ring-canal.

TheYoyage of H .M S'ChaQen^er

Siphonophorae Pl.XLII.

CYMBA CRYSTALLUS (CUBOIDES).

PLATE XLI11.

Order DISCONECTjE.

Family Velelliu k.

Armenista sigmoides.

(ZOOL. CHALL. EXP.— PART LXXVII. — 1888.)— Hhhll.

PLATE XLIII.

Armenista sigmoides, n. sp. (p. 84).

Diam.
Fig. 1. Apical view of the conn (from above). The diagonal crest of the pneumatophore divides the
exumbrella into an antero-dextral and a postero-sinistral half. The limb of the umbrella is
octolobate, ........... nat. size

Fig. 2. Basal view of the corni (from below). The large sterile central siphon is surrounded by a

corona of numerous small sexual siphons, and these by a double corona of filiform tentacles, nat. size

Fig. 3. Half lateral, half superior view of the corm. Numerous filiform tentacles are prominent
beyond the limb of the umbrella. The vertical diagonal crest of the pneumatophore exhibits
the branched canals of the exumbrella, ....... nat. size

Fig. 4. Frontal section through the corm (or vertical transverse section), ph, Central chamber of the
pneumatocyst (pf); ce, canals of the umbrella; uu, limbus umbrella;; us, glands of the
umbrella margin; uc, centradenia ; uh, hepatic vessels; tin, renal vessels; t, tentacles; <js,
gonostyles (sexual siphons) ; g, gonophores ; sa, sterile central siphon ; sf, longitudinal folds
of its inside ; so, the octolobate mouth, . . . . . . . x 4

Fig. 5. Pneumatocyst of a young corm, seen from above. Concentric ring-chambers with their pores

of communication (pneumothyra;, pg) ; pe, their external openings (stigmata), . . x 2

Fig. G. Central part of the pneumatocyst of a young corm, seen from below, highly magnified. The
central chamber (ph) is confluent with eight radial chambers (pq), each of which bears below
a branched trachea. The surrounding concentric ring-chambers ( ph) are connected by pores
of communication (pneumothyrse, pg), . . . . . . . x 20

Fig. 7. Basal view of the isolated centradenia (uc) and the central siphon (sa), from below, cm,

Gastro-canal system of the subumbrella ; so, mouth, . . . . . x 2

Fig. 8. A single gonostyle or sexual siphon, gs, Its stomach ; g, gonophores ; leu, cnidonodes ; so,

mouth, . . . . . . . . . . x 20

Fig. 9. A medusiform gonophore, detached from the stem (Discom itra), highly magnified, w, Subum-
brella ; or, radial canals accompanied by yellow cells (xanthellse); t, rudimentary tentacles ;
s, the incipient manubrium, . . . . . . . x 100

Fig. 10. A branched trachea of the' pneumatocyst.

The Voyage oflLM.S.'Challei

nupliorar PI XI. III.

ARM EN ISTA SlGMOlDES.

PLATE XLIV.

Order DISCONECM.

Family Velellid m.

1!<i1 ari< i cristata.

PLATE XLIV.

Rataria cristata, n. sp. (p. 79).

Diam.

Fig. 1. Apical view of the corm (from above). uf, Vertical sail; pq, octolobate central disc of the
pneumatocyst ; pl\ its concentric ring-chambers ; um, margin of the umbrella ; gs, gonostyles
(shining through) ; t, tentacles, . . . . . . . x 20

Fig. 2. Basal view of the corm (from below), so, Mouth-opening of the central sterile siphon ;

gs, sexual siphons (gonostyles) ; um, margin of the umbrella ; /, tentacles, . x 20

Fig. 3. Half lateral, half superior view of the corm, swimming in the expanded state, uf, Vertical
sail ; pf, pneumatocyst ; ph, its central chamber ; we, centradenia ; um, margin of the
umbrella ; t, tentacles ; gs, gonostyles ; sa, central siphon ; so, its mouth, . . . x 1 2

Fig. 4. Lateral view of the corm, in the contracted state. Characters as in fig. 3, . . x 12

Fig. 5. Frontal section through the corm (or vertical transverse section). Characters as in figs. 1 and

3. si, Gastrobasal plate ; cm, hepatic vessels ; ce, pallial vessels ; g, gonophores, . . x 20

Fig. 6. Horizontal section through the corm, somewhat oblique. The median part of the section
exhibits the centradenia (uc), with the hepatic vessels (cm). The right (inferior) half of the
figure shows the transverse sections of the gonostyles (gs) and tentacles (t) ; the left (superior)
half the peripheral ring-chambers of the pneumatocyst (pic), . ■ ■ x 20

Fig. 7. Horizontal section through the corm, in a transverse plane more highly situated than fig. 6.
pf, Pneumatocyst ; pJc, its concentric ring-chambers ; uc, centradenia ; em, hepatic vessels ;
ce, pallial vessels of the umbrella margin, . . . . . . x 20

Fig. 8. Pneumatocyst of another corm, isolated, seen from above, po, Central stigma ; pe, antero-
sinistral stigma ; pe", postero-dextral stigma ; pq, octolobate periphery of the central disc ;
ph, concentric ring-chambers, . . . . . . . x 20

Fig. 9. The same pneumatocyst, seen from below, pk, Concentric ring-chambers ; j>t, tracheae, . x 20

Fig. 10. Margin of the umbrella ; highly magnified.

Ilie Voyage oi II MS Challenger

Siphonophorac I 'I XLIV.

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RATARIA CRISTATA

PLATE XLV.

Order DISCONECTvE.

Family Pokpitidj;.

Porpita fungia.

(ZOOL. CHALL. ESP. — PART LXXVII. — 1888.) — Hhllh.

PLATE XLV.

Porpita fungia, n. sp. (p. 67).

Fig. 1. Vertical meridional section through the corm. p, Pneumatocyst ; ph, its central chamber ; ph, con-
centric ring-chambers ; p1, tubercles of the upper surface ; p'1, thickened ebitinous layers of the
upper wall ; p3, septa between the ring-chambers ; p>4, under surface of a high radial fold ;
pe, stigmata; uh, hepatic vessels of the centradenia; un, its renal vessels; uu, limbus umbrella?;
t, tentacles ; gs, gonostyles ; so, their mouth ; rj, gonophores ; st, tabula gastrobasalis ; sro, stomach
of the central siphon ; s/j its basal fissures (ostia of the radial canals) ; sr, proboscis ; ss, mouth.

Fig. 2. A portion of the exumbrella ; highly magnified, we, The radial folds ; ce, pallial canals ; pe, radial
rows of stigmata.

Fig. 3. Basal view of the centradenia, isolated by maceration, un, The white annular kiduey ; sh, the brown
liver ; si, central star composed of hepatic vessels ; sx, basal insertions of the sexual siphons ;
cr, radial canals.

Fie. 4. Basal view of the central siphon, the walls of which are highly contracted and the octolobate mouth
widely opened. In the fundus of the stomach are visible eight pairs of fissures (sf), the gastral
openings of sixteen radial canals, sw, Radial folds ; si, thickened labial margin of the mouth.

Fig. 5. A radial segment of the pneumatocyst (pf) of another Porpita (umbella). The upper surface of the
float exhibits numerous radial rows of stigmata (^>e) in the back of prominent ridges, ph, Con-
centric ring-chambers ; ph, central chamber.

Fie. 6. A small portion of the centradenia in horizontal section ; highly magnified, sa, Central siphon ;
sic, radial folds of its inside ; d, entoderm ; e, exoderm ; m, muscles ; si, lamina gastrobasalis ;
pt, tracheae ; Jeb, cnidoblasts ; ha, auroblasts (air-secreting cells).

Fig. 7. A small portion of the kidney (un), in horizontal section ; highly magnified. Characters as in fig. 6.
cm, Hepatic vessels.

Fig. 8. A small portion of the kidney (un) and a sexual siphon (sx) in vertical section. Characters as in
figs. 6, 7. e1, Exoderm of the subumbrella; e2, inner apophyses of it, piercing the fulcrum (z);
e3, air-secreting exoderm. Some trachea? (pit) pierce the fulcrum and pass into the exoderm of the
sexual siphon (sx).

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PLATE XLVL

Order DISCONECT.E.
Family Poepitid.e.
Porpitella pectantJi is.

Diam.

PLATE XLVI.

Porpitella pectanthis, n. sp. (p. 64).

Figs. 1,2. The complete corm, seen from above in the right half (l), from
below in the left hah0 (2). In the centre is visible the mouth of
the sterile central siphon, surrounded by a corona of sixteen small
gonostyles (or sexual siphons). The right half of the figure (l)
shows the half of the radiate pneumatocyst, with eight marginal
lobes. The margin of the umbrella is beset with a series of glands
(dark points) and surrounded by a corona of numerous tentacles,
composed of sixteen radial bunches, . . . . x 4

Fig. 3. Vertical meridional section through the lenticular biconvex umbrella
and its appendages, ph, Central chamber of the pneumatocyst ;
pq, one of the eight radial chambers ; pk, concentric ring-
chambers ; urn, limbus umbrellas ; t, tentacles ; uc, centradenia ;
cm, hepatic vessels ; st, gastrobasal plate ; sa, central siphon ;
so, its mouth, . . . . . . . x 8

Fig. 4. Radial segment of the pneumatocyst, seen from above ; highly
magnified, po, Central stigma; pe, peripheral stigma; ph,
central chamber; pq, radial chamber; pk, concentric ring-chambers;
pg, pneumothyrge (pori communicantes), . . . x 40

Fig. 5. Radial segment of the pneumatocyst, seen from below ; highly
magnified, ph, Central chamber ; pq, eight radial chambers ;
pe, their stigmata (shining through) ; pt, tracheae ; pk, concentric
ring-chambers, . . . . . . x 20

Fig. 6. Vertical section through the centre of the umbrella. Characters as

in figs. 3, 4. pt, Tracheae, . . . . x 20

Fig. 7. Vertical section through the peripheral part of the umbrella.
Characters as in figs. 3, 4. iv, Subumbrella ; pt, trachea? ; us,
muciparous glands of the umbrella-margin, . . x 20

Fig. 8. A portion of a single trachea, . . . . . . x 300

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PORPITELLA PECTANTHIS.

PLATE XLVII.

Order DISCONECM.

Family Porpitid^.

Porpema medusa.

(ZOOL. CHALL. ESP. — PART LXXVII. — 1888.) — Hhllll.

PLATE XLVII.

Porpema medusa, n. sp. (p. 61).

Diam.

Fig. 1. The medusiform conn, seen from the exuinbrellar or superior face. The central part of the
exumbrella exhibits the radial rows of stigmata in the pneumatocyst, whereas in the
peripheral part the forked branches of radial pallial canals are visible. The numerous
tentacles of the surrounding submarginal corona are smallest in the uppermost, row, . x 10

Fig. 2. Lateral view of the same corm in profile. (Compare figs. 3 and 4), . . . x 10

Fig. 3. Lateral view of the same corm, after removal of the tentacles, uu, Limbus umbrellae ; t', the
uppermost row of small tentacles ; hi, polygonal facettes where the numerous tentacles
have been attached to the subumbrella ; sx, sexual siphons ; sh, central siphon ; sr,
proboscis; so, its mouth, . . . . . . . x 10

Fig. 4. Vertical meridional section through the same corm. ph, Central chamber of the pneumato-
cyst ; pic, its concentric ring-chambers ; x, gastrobasal plate ; uc, centradenia ; w, subum-
brella ; t, tentacles ; sx, sexual siphons; sh, central siphon ; sr, proboscis; so, mouth, . x 10

Fig. 5. Central portion of the subumbrella, seen from below, sz, Central siphon ; so, its mouth ; sx,

sexual siphons ; ;/, gonophores, . . . . . . . . x 20

Fig. 6. Horizontal transverse section through the middle portion of the corm. uc, Centradenia ;
cm, its hepatic vessels ; cr, radial canals, running between eight chambered radial portions
of the pneumatocyst ; cz, coronal canal ; fit, insertions of the tentacles, . . . x 20

Fig. 7. Central portion of the pneumatocyst, seen from above, ph, Central chamber ; pq, eight
radial chambers ; pic, two concentric ring-chambers ; pr, radial furrows ; pe, eight peri-
pheral stigmata, . . . . . . . . . x 20

Fig. 8. Horizontal transverse section through the pneumatocyst and the uppermost portion of the

centradenia (in the height of x in fig. 4). Characters as in figs. 6 and 7, . . x 20

Fig. 9. Horizontal transverse section through the lowermost portion of the centradenia (uc). sf,

Ostia gastralia (openings of the eight radial canals into the central siphon), . . x 20

Fig. 10 Horizontal transverse section through the central siphon, with eight radial folds, d, Ento-
derm ; z, fulcrum ; e, exoderm ; sc, gastral cavity, . . . . . x 20

Fig. 11. Two muciparous glands of the umbrella-margin, . . . . . . x 400

Fig. 12. A small portion of the umbrella-margin, cr, Radial canals ; us, muciparous glands, . x 200

The Voyage ofH.M.S.'Challengci

Siphonopliorae PI.XLVJI.

PORPEMA MEDUSA.

PLATE XLVIIJ.

Order DISCONECTiE.
Family Porpitidj.

J

Porpalia 'prunella.

PLATE XLVIII.

Porpalia prunella, n. sp. (p. 58).

I Ham.

Fig. 1. The medusiform corm, seen from the superior or exumbrellar face. The
radiate pneumatocyst shines through the central part of the ex-
umbrella, which exhibits numerous radial ribs and rows of stigmata.
The margin of the umbrella is beset with glands and surrounded by
a corona of tentacles arranged in eight radial bunches, . . x 1 0

Fig. 2. Lateral view of the same corm in profile. A deep subumbrellar circular
furrow separates the margin of the umbrella (w) from the multiple
corona of tentacles (t). Many tentacles are detached and their
insertions only visible (tu) ; iv, subumbrella ; ue, exumbrella. The
large central siphon (sa), with a long proboscis and octolobate mouth
(ss), is surrounded by a corona of eight peripheral smaller siphons
(sx) bearing numerous medusiform gonophores (g), . . . x 20

Fig. 3. Vertical meridional section through the main axis of the same corm.
The central air-chainber (ph) of the campanulate pneumatocyst is
separated by the subspherical centradenia (tic) from the base of the
central siphon (sh) ; so, central mouth ; st, lamina gastrobasalis. Two
smaller sexual siphons (sx) bearing gouophores (g) are visible beyond
the corona of tentacles (t). The other characters as in fig. 2, . x 20

Fig. 4. Apical view of the pneumatocyst (from the superior side), with radial

marginal lobes expanded, . . . . . . x 10

Fig. 5. Basal view of the pneumatocyst (from the inferior side), with numerous

simple tracheae, . . . . . . . x 10

Fig. 6. A radial segment of the pneumatocyst (fig. 5), from the inferior side.

p?i, Central chamber ; pk, concentric chambers ; pt, simple tracheae, x 50

Fig. 7. A radial segment of the centradenia, from the superior side, taken from
Porpita fungia (PI. XLV.). The numerous dentate radial laniellse,
which arise from the upper surface of the central gland, fit into
corresponding radial furrows between the crests arising from the
lower side of the pneumatocyst, . . . . . x 20

Fig. 8. Eadial section through the middle portion of the pneumatocyst,
exhibiting three concentric air-chambers (pk). pg, Pneurnothyrse
(pori communicantcs) ; pe, stigmata ; pt, tracheae, . . . x 80

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PORPALIA PRUNELLA

PLATE XLIX.

Order DISCONECT^.

Family Discalid^e.

Figs. 1-6. Discalia medusina.
Figs. 7-12. Disconalia gastrdblasta.

(zool. chall. exp.— pakt Lxxvu. — 1888.) — Hhhh.

PLATE XLIX.

Figs. 1-6. Discalia medusina, n. sp. (p. 46).

Fig. 1. Basal view of the medusiforiu octoradial conn (from the inferior or suhumbrellar face). The
central siphon, with an octolobate month, is surrounded by a corona of eight palpons which
bear numerous small medusiform gonophores on their basal pedicle. A corona of eight simple
perradial tentacles, bearing a terminal cnidosphere, is placed between the palpons and the
octolobate limbus umbrella?, which is beset with a band of glands.

Fig. 2. Exumbrella (apical view of the corm). po, Central stigma ; pe, corona of eight peripheral stigmata ;
nu, trie eight marginal lobes ; /, tentacles.

Fig. 3. Lateral view of the corm, in profile; the tentacles (t) are bent downwards, po, Central stigma; pe, peri-
pheral stigmata ; mm, margin of the flat octolobate umbrella ; gs, gonopalpons ; g, gonophores ;
sa, central siphon ; so, its mouth.

Fig. 4. Meridional section through the same corm. ph, Central air-chamber of the pneumatocyst ; pq, radial
air-chamber ; /, tentacles ; uc, centradenia ; st, gastrobasal plate. Other characters as above.

Fig. 5. Meridional section through the pneumatocyst alone, ph, Central chamber ; po, its stigma ; pq, two
of the eight radial air-chambers ; pe, their stigmata ; pt, tracheae.

Fig. 6. Vertical section through the limb of the umbrella (mm), cr, Radial canal ; ec, circular canal ;
us, marginal muciparous gland.

Figs. 7-12. Disconalia gastroblasta, 11. sp. (p. 48).

Fig. 7. Esumbrella (apical view of the umbrella, from above), with the octoradial system of the superficial
exumbrellar canals. Eight perradial main vessels arise from the small ring which surrounds the
apical stigma, and branch dichotomously. Their anastomosing branches unite in an octagonal
coronal vessel, from which the simple peripheral radial canals of the limb arise. The octolobate
margin is beset with a corona of glands.

Figs. 8, 9. Octoradial chamber-system of the air-filled pneumatocyst ; fig. 9, superior or apical view (right
half of the figure) ; fig. 8, inferior or basal view (left half). The central air-chamber is sur-
rounded by a regular corona of eight interradial air-chambers (pq), and these by a peripheral
octolobate corona which is composed of numerous concentric ring-chambers (pk). pe, Stigmata
of the upper face ; pt, trachea? of the lower face ; pg, interradial pncumothyrse (pori communicantes).

Fig. 10. Apical view of the octagonal centradenia (from above), with the brown ''liver-star," or the system of
eight radial, dichotomously branched hepatic vessels.

Fig. 11. Horizontal transverse section through the basal portion of the central siphon (sa), and the sur-
rounding centradenia (uc). The octolobate margin of the umbrella exhibits the transverse
sections of the basal portions of the tentacles (in a double row).

Fig. 12. Horizontal transverse section of the umbrella, somewhat above the plane of fig. 11. In the centre is
visible the half of the gastrobasal plate (with four gastral ostia). cm, Hepatic canals.

TheVovage cil'll M.S. "Challenger

Siphonophorae PI. XI. IX

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1-6. DISCALIA MEDUSINA . T -12 . DISCONALIA GASTROBLASTA

PLATE L.

Order DISCONECT^E.
Family Discalid^e.
Disconalia gastroblasta.

PLATE L.

Compare figs. 7-12 in PL XLIX.

Disconalia gastroblasta, u. sp. (p. 48).

Fig. 1 . Basal view of the medusiform octoradial norm (seen from the subumbrella). The central sterile siphon
exhibits an octolobate mouth-opening, and is surrounded by a corona of sixteen reddish-yellow
palpons which bear numerous medusiform gonophores on their basal portion. An octoradial
corona of numerous tentacles, arranged in eight equidistant bunches, is placed between the
corona of palpons and the octolobate margin of the umbrella. Each tentacle bears three longitudinal
rows of tentilla, or of pedunculate cnidospheres, two paired lateral and one inferior row.

Fig. 2. A fertile palpon, beset in the red distal half (q) with eight longitudinal rows of cnidonodes (/.;), in the
yellow proximal half with clusters of medusiform gonophores (Discomitrae, g).

Fig. 3. The octolobate mouth of the large central siphon ; its labial margin is armed with a series of cnido-
nodes.

Fig. 4. A group of tentacles (three larger and four smaller) and their insertion into the subumbrella.

Fig. 5. A single tentacle, with its three rows of tentilla (an odd inferior and two paired lateral rows).

Fig. 6. A single tentillum. d, Axial column composed of large discoidal entoderm-cells ; e, exodermal
epithelium ; z, fulcrum between them ; k, terminal cnidosphere.

Fig. 7. Apical view of a Discomitra (or a medusiform gonophore). u, Exumbrella ; w, subumbrella ; cr, four
crossed radial canals.

Fig. 8. Lateral view of the same Discomitra, in profile, cr, The four radial canals ; ec, ring-canal of the
umbrella margin.

Fig. 9. Apical view of a young Discmtula (octoradial medusiform larva of Discoiialia). The pneumatocyst
(yellow) appears through the central portion of the (blue) exumbrella. ph, Central air-chamber;
po, its stigma ; pq, eight radial air-chambers ; pe, their peripheral stigmata ; us, muciparous glands
of the umbrella-margin ; t, tentacles ; k, cnidospheres.

Fig. 10. Basal view of a somewhat older Disconula. The octolobate mouth of the central siphon and the
corona of eight (red) incipient palpons are visible in the centre of the subumbrella. Each tentacle
bears a terminal bunch of four tentilla (k). Characters as in fig. 9. (Compare on these larvae,
pp. 39, 45, 56, and Discalia, p. 46, PI. XLIX. figs. 1-6.)

The Voyage of II M S Challenger
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