J>

THE DANISH

INGOLF-EXPEDITION.

VOL. V, PART 6.

CONTENTS:

"HJALMAR BROCH: HYDROIDA. (I.

v.^

I 0
i □

PUBLISHED AT THE COST OF THE GOVERNMENT

BY
THE DIRECTION OF THE ZOOLOGICAL MUSEUM OF THE UNIVERSITY.

•^*AjL4e^"

COPENHAGEN.

H. HAGERUP.

PRINTED BY BIANCO LUNO.

ig r6.

THE DANISH INGOLF- EXPEDITION.

VOLUME V.

6.

HYDROIDA.

(PART I.)

BY

HJALMAR BROCH.

WITH 2 PLATES AND 20 FIGURES IN THE TEXT.

-*4KiHf<-

COPENHAGEN.

PRINTED BY BIANCO LUNO.
1916.

CONT

Preface

i

I. Introductory Notes 3

a. The Hydroid Gonophores bearing on classification 4

b. The comparative anatomy of the nourishing individ-
uals and the system of the athecate hydroids 7

II. Athecate Hydroids of the northern Atlantic 11

Section Capitata 11

Family Corynidae II

Coryne Gaertner 13

Coryne Sarsii (Loven) 14

Loveni (M. Sars) 15

pusilla Gaertner 16

— sp. aff. Hincksi Bounevie 18

Family Myriothelidae 1 s

Myriothela M. Sars 19

Myriothela phrygia (Fabrieius) 19

Family Tuiulariidae 21

Tu&ularia L i n n e 22

Tubularia pnlclier ( Ssemundss on ) 22

— indivisa Li n n e 24

regalis Boeck 25

larynx Ellis etSolander 27

sp. iudet 28

Corymarpha M. Sars 29

Corymorpha nutans M. Sars 31

glacialis M. S ars 32

groenlandica 1 A 1 1 m a 11 ) 33

ENTS

Page

( 'orymorpha sp. indet 37

Section Filifera 38

Family Clavidae 38

Clara G 111 eli 11 3S

Clava multicornis (Forskal ) 38

Mil, •mi Norm an 40

Merona cornucopiae Norman 40

Monobrachium M ereschko wsky 42

Mondbrachium parasitum Mereschkowsky 42

Family- Bougainvilliidae 43

Hydractinia van Beneden 44

Hydraclinia Sarsii St eenstrup 45

echinata (I'leming) 46

carica Bergh 48

Bougainvillia Lesson 49

Bougainvillia conferta I Aid er) 50

Perigonimus M. Sars 51

Perigonimus repens ( \V ri gh t) 52

abyssi G. O. Sars 53

roseus ( M. S a rs ) 54

Family Eudendriidae 56

Eudendrium Ehrenberg 57

Eudendrium rameum (Pallas) 57

ramosum (Linne) 59

Wrighti Hartlaub 60

annulatum Norman 62

capillar,' Alder 62

418 8 S

Preface.

The investigation of the large Danish collections of hydroids from the Faroe Islands, Iceland,
and Greenland, and the researches into the interesting material brought home from the In go If
Expedition, have realised great results. In fact, several points of dispute as to the classification of
northern species have been settled. In the first place, the Danish collections contain original specimens
of some species which have been described as new several times after being originally recorded. In
other cases, the large number of specimens tend to bridge the division between species which have
hitherto been looked upon as "good" ones. It is, indeed, a matter of regret that deficiencies of diagnosis
and inaccuracy of design have frequently put obstacles to the recognition of species previously recorded,
and that the literature has, consequently, been encumbered with synonyms which we should rather
have done without. This inconvenience, in fact, enforces the necessity of giving full and exhaustive
accounts of every single species. The American investigators, indeed, on the pattern of Nutting
have long tried to give brief diagnoses and drawings of all American species. But it must be observed
that, because of the impressionist way of drawing, the illustrations are, as a general rule, somewhat
wanting in accuracy, and to the brief diagnoses there is the objection that they are often too summary
to give exhaustive account of the distinguishing features. On the whole such weak points as appear
in the last works of Allman, have gone down to his epigones. Great difficulties, indeed, are in this
way given to students of the geographical distribution of the hydroids. No doubt, more species than
those which are at present pointed out by literature, are common to the European and the American
seas. But in general it proves impossible to form, on the ground of the brief diagnoses, a well-founded
opinion as to the virtual qualities of many species. As far as the European species are concerned, we
are fortunate in possessing the classic work of Hi neks, A History of the British Zoophytes. However,
since the appearance of that work, plenty of fresh subjects have been added by descriptions of several
species and genera which can hardly all be maintained, and publications have of late appeared in such
abundance that it proves difficult to students of this group of animals to find their way through the
crowded matter.

These are the reasons why I have tried to give new and detailed diagnoses of every single
species in question. The diagnoses are essentially founded on the copious material occurring in the
Danish collections. Of synonyms I have only selected those of absolute necessity. Detailed accounts
of synonymy are found — as far as earlier literature is concerned — in the excellent treatises of Be dot,

The Ingolf-Expedition. V- 6. I

HYDROIDA

Materiaux pour servir a l'histoire des Hydroi'des, and - - regarding recent literature on northern
hydroids — in the groupings framed by Jaderholm (1909), Broch (1909), and Kramp (1914). As far
as possible, the various species are accompanied by maps illustrative of the geographical data in the
northern Atlantic. Besides the collections the recent literature has served as basis. In this respect
the groupings occurring in the works of Bonnevie (1899), Jaderholm (1909), Broch (1909), Sse-
mundsson (1911), and Kramp (1914), have proved particularly available.

I have made it a point to define precisely the limits of genera and families by full diagnoses,
and at the same time I have tried to account for the leading principles I hold to for the purpose of
division and classification. The various authors have maintained various opinions as to the systematic
principles of classification; many of them have disregarded phylogeny and allowed biological considera-
tions to play a predominant part; consequently the circumscription of genera has been practised in
most various ways. To leave no opening for misunderstanding I have thought it necessary to give
a detailed account of each species in question, even if the work should be delayed and grow a little
broader than I wanted. However, I hope that in this way the extensive and methodical Danish col-
lections will tell better and to fuller advantage than otherwise.

Trondhjem the 22nd August /q/j.

I. Introductory Notes.

Scarcely in any other part of the animal world greater difficulties are thrown in the way of
the systematist than those occasioned by the lowest Coelenterata, impeding the attempts to establish
a natural grouping of the hydroids and their attendants, the hydromednsae. This is due not only to
the actual deficiencies of our knowledge of these low organisms, but also to the fact — as pointed
out by Kiihn in his excellent summary (1913) — that the groups present partly a confused series of
adaptations and phenomena of convergency, partly the occurrence of medusae of widely divergent
development as companions of closely allied hydroids or, vice versa, closely allied medusae accompanying
hydroid polyps divergently developed. It is a striking fact that in certain species, for instance the
Codomdcr, the phylogenetic development and differentiation of form of the medusae have been com-
paratively stunted, whereas the polyps {Corynidce, Pcnnariidcr, Tubulariidir) have developed hetero-

geneously so as to present a large series of various forms. The exact reverse is represented
by the homogeneous polyps of the family Bougainvilludcr. forming the nurse generation of the hetero-

•

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geneously developed hydromedusa: of the families Margelida and Tiaridce. The possibility of construct-
ing a safe system common to medusas and hydroid polyps, indeed, appears remote. For in the first
place the two "generations", on account of their excessive abundance of species, have had to be treated
separately, each generation by specialists of its own, and moreover, we are in fact still in the dark as
to which of the two generations is to be regarded as the primitive or the phylogenetically older.

When looked upon as a whole the group of Zoophytes must be characterized as a very low
group of animals. In the nurse generation as well as in the free-swimming medusae the structure
of the individual is very simple, though the medusae after all must be said to be a little higher
organised than the polyps. In addition to the two primary layers of cells, the endoderm and the ecto-
derm, occurs in the medusae a "mesoglcea", whose descent from one or the other of the primary layers
is not yet definitely ascertained as far as all species are concerned. However, a mesoglcea also occurs
with some hydroids, for instance the "parenchyma" of the Tubitlariidcc, which is a typical endodermal
formation.

To students of the hydroids it very soon becomes obvious that the leading systematic characters

have been derived from such criteria as urge themselves on a superficial view of the animals, while,

contrarily to the method practised in investigating most other groups of animals, the inner

anatomy is all but entirely left out of account. This is due to the generally accepted view that the

1*

HVDROIDA

.structure of the hydropolyps is throughout quite homogeneous and accordingly affords no holds of
use to the systematist. A careful study, however, of the slight information occurring in the literature as
to the structure of the polyps, will show that the old view is wrong. In this connection it will be
sufficient to refer to the excellent passage written by Kiihn (1913), Die Ausbildung des Polypenkorpers,
in which are mentioned several examples of the heterogeneous structure of the polyps in the various
groups of hydroids.

Nevertheless Kiihu himself (1913), in constructing his system of the hydroids, has, according
to the old practice, left this fact almost wholly out of account. I will afterwards come back to the
subject and point out how unreasonable it is to set aside this part of systematics even though a
thorough investigation of the anatomy of the polyps may seem almost impracticable because of the
state of preservation in which the hydroids generally occur in the materials of the great expeditions
and collections. In fact, it is confirmed that Levinsen (1893) is right, emphasizing that the systematist
in treating of hydroids should rather lay stress on all about the nourishing individuals than on the
varying development and organisation of the generative individuals.

a. The Hydroid Gonophores bearing on classification.

Our knowledge of the hydroids has advanced a vast stride ahead owing to the thorough
researches of Kiihn into the development and the organisation of the gonophores (1910). As to the
importance of the gonophores to systematics, it has lately (1913) been asserted by the same author
that no weight whatever can be given to the various gonophoral development, but that particular
stress should be laid on the structure of the full-grown gonophores. On account of difference of structure
he distinguishes between four types of sessile gonophores: eumedusoids, cryptomedusoids, heteromedusoids,
and, finally, the simple gonophores, called styloids (Bonnevie 1898). The eumedusoid gonophores, indeed,
retain the structure of the medusa throughout, and occasionally breaking away {Campanalaria Integra
Mc. Gillivr. -- Agasfra mira Hartlaub) occur like defective medusa. The structure of the crypto-
medusoid gonophores is more reduced. Certainly they keep their endocodon and their umbrellary cavity,
but have a single-layered umbrellary endoderm; however, also of cryptomedusoids occur exceptional
instances breaking away, as in Pachycordylc Weismanni Hargitt. The heteromedusoids are entirely
wanting the umbrellary endoderm, and the inner umbrellary ectoderm is formed by delamination, not
by invagination of the outer ectoderm (endocodon). The simplest gonophores, finally, are without any
trace of medusoid organisation. These four types of sessil gonophores Kiihn (1913) regards as char-
acters important to the systematist for the division of hydroids into genera.

Stechow (1913) in his important work on Japanese hydroids occupies another standpoint,
attaching more importance to the conditions of the gonophores. Thus he draws nearer to earlier
principles of classification, but at the same time he tries to make his systematic division more manage-
able by drawing out characters from the outward morphology of the colonies, thus effecting the
transition to the American school. The Americans, headed by Nutting, look on classification only as
"a matter of convenience", and accordingly in their groupings, as a matter of fact, relinquish the idea
of constructing a natural system aiming at summing up and drawing by critical sifting of the char-
acters a skeletonlike picture of the phylogenetic affinities of the group of animals in question. Con-

HYDROIDA

*

:■?

sequently the system brought about by the American investigators, picking up heterogeneous char-
acters, is indeed, as I have shown in an earlier treatise (1909), to a great extent one of arbitrariness,
placing the species now in one, now in another genus, according to the character it is thought desir-
able to emphasize at the moment. The system has, in this way, become a matter of chance.

Before proceeding to the special explanation of the several species of hydroids and their occur-
rence in the seas of the northern Atlantic, we, therefore, must try to realize, from a systematic and
phylogenetic point of view, the value of each single character. In the first instance the question must
be answered what part the gonophores play as to the phylogeny of the hydroids or, in other words,
what importance has to be attached to the gonophores and their conditions for the purpose of
classification.

The application of the characters of the gonophores as distinguishing marks of higher system-
atic unities, of families, or of subfamilies, has been abandoned by all modern investigators of the
hydroids. On the other hand, it is held by several investigators that they are of importance as to the
limitation of genera. The last significant publications maintaining this view, are those of Kuhn (1913)
and Stechow (1913). Kuhn, however, applies the characters of the gonophores with much caution
and discretion, while Stechow, as a glance at his tables (1913, p. 36 and the following pages) suffices
to show, undiscerniugly recurs to the principle of laying the main stress on the "medusa" as contrasted
with the "sporosac". In fact, as long as the limits between these designations are not more precisely
defined, they will be subject to much arbitrariness. An interesting instance is afforded by the point
in dispute, where the limits are to be drawn between the genera Coryne and Syncorync. The old
criterion, accepted by All man and other investigators, was the free medusa as contrasted with the
fixed gonophore or sporosac, and, to all appearance, it is the same limitation Stechow tries to
maintain in his table. Indeed, this principle of limitation was only supportable on the ground of the
deficient knowledge of the organisation and development of the hydroid gonophores attained to in
All man's clays. Kuhn, therefore, (1913, p. 229) is seen to take quite another departure, defining the
Syncoryne as including all species having "medusae", while the Coryne is distinguished by styloid
gonophores. It is evident from Ktihn's previous argument (1. c. p. 174) that under "medusae" he also
includes the eumedusoids which normally do not break loose, and that accordingly Coryne, in his
opinion, exclusively embraces species having styloid gonophores.

Parallel to these genera Stechow also treats of Podocoryne (with medusa;) and oi Hydr actinia

(with "sporosacs"). Kuhn (1913, p. 227) groups them in the following vague way:

Podocoryne )

\ Medusen (Margelinen), Eumedusoide, Cryptomedusoide, Styloide.
Hydractinia J

From his premises (1. c. p. 226) it appears that he agrees with most modern investigators, think-
ing it right that the two old genera should be merged into one, Hydractinia\ for he states that in
fact we have here before us a series of closely allied forms, in which "zwischen Arten mit Vollmedusen
und eiufachen Medusoiden die verschiedensteu Ubergange bestehen". Thus Kuhn, elsewhere considering
the characters of the gonophores as significant generic criteria, in this place actually reduces them
to mere specific characters.

In another connection Kuhn (1913 p. 197) gives an instance of the fact that the sexes in

HYDROIDA

one and the same species can be distinguished by different types of gonophores; thus the female
gonophore of Laomedea flexuosa Hi neks is heteromedusoid, while the male gonophore is styloid.
This strongly defined sexual dimorphism is most interesting, and the question is obvious whether the
case is a solitary one, or if in other species other types of gonophores, of those stated by Kiihn,
might perhaps be found united in one and the same species. On that account I have (191 5) more
closely examined the development of the gonophores of, among others, the Tubularia indivisa Lin.
and the Tubularia rcgalis Boeck, two species in which a marked sexual dimorphism is found pro-
nounced in the external characters of the gonophores. The examinations resulted in the startling result
that the female gonophores of both species are eumedusoid, though not equally high in medusoid
organisation, whereas the male gonophores of both species are heteromedusoid and of entirely the
same organisation, and development as the gonophores of the genus Lampra Bonnevie (1898) (comp.
Broch 1915). It is owing to the gonophores that Lampra is separated from Corymorpha, the latter
genus producing free medusae or having gonophores eumedusoid. Acting on this principle of division,
as far as the species of the genus Tubularia are concerned, we should have to separate the male
Tubularia indivisa and Tubularia rcgalis as a new genus, while the female individuals belonging to
the same species would retain their places1.

The outcome of the searching studies of the last years shows, indeed, that in proportion as a
greater number of species have been examined, the more evidently the characters of the gonophores
appear as criteria of species. The increasing knowledge of the gonophores makes ever clearer that
the gonophores alone cannot form the base of any division of genera, but at most serve as second-
arily corroborative.

The free medusae show throughout a greater abundance of forms developed than the polyps,
which are more conservative. No doubt, the medusae present a series of phenomena of adaptation
and, accordingly, display several characters of convergency, to which the systematists are inclined to
attach a greater phylogenetic value than is their virtual due. Nowhere, I dare say, the adaptations
to habits of life and the accommodations to varying physical conditions play such a part as with the
pelagic organisms, to which the slightest variation of salinity and of temperature causes great
changes of viscosity of the surrounding water, decisive of the adaptation of their suspension organs.
Therefore, the hydroid systematist should not lay too much stress on the statements of the medusoid
specialist as to the systematic grouping of the free-swimming generation; phylogenetically the char-
acters of the nurse generation are of the greatest interest. A similar state of things urges itself with
the sessile gonophores. It is a circumstance of vital importance to the maintaiuauce of the species,
that the generative individuals are able to accommodate themselves quickly to the peculiar conditions
of life to which the species is subjected. What I observed in my treatise on the Stylastcridcc (1914),
is fully applicable (or even more so) to the case under consideration: "Owing to their conservatism in
development the polyps are of the most important phylogenetic interest. The gonophores, the genera-
tive individuals, on the other hand, might almost be said to be a playball in the hands of chance
biological conditions and thus phylogenetically have much less interest".

1 The possibility of a fusion of four species is precluded, as in Tubularia indivisa and in Tubularia regalis (J and 9
occur in the same colony.

HYDROIDA

On account of their dependence on outward conditions and their power of plastic accommodation
to biological influences, the gonophores are unsuitable for basis of division into genera. On the other
hand, the genera, owing to the conditions of the gonophores, often fall into a series of biological
groups (or subgenera). The systematists who lay the main stress on the gonophores in establishing
the system, in fact apply biological conditions as fundamentnm divisionis, and let phytogeny, the pro-
perly governing principle of systematic inquiry, recede into the shade.

b. The comparative anatomy of the nourishing individuals, and the system of the

athecate hydroids.

An exact review of the researches of the last years makes ever clearer, as also appears from
the statements above, the correctness of Levins en's view (1893), maintaining that in the great classifica-
tion of the hydroids the main stress must be laid on the peculiar conditions of the nourishing polyps,
and reducing at the same time the modifications of growth and the conditions of the gonophores as
characters of subordinate importance. Later investigators1 have, indeed, attached ever more importance
to the conditions of the polyps. But in so doing they have almost exclusively taken into considera-
tion such morphologic criteria as urge themselves on a superficial view of the polyps. The inner
anatomy, on the contrary, has been disregarded. Kuhn (1913) certainly by the way points out that
the inner anatomy can be different in the different groups. He treats (1. c. p. 50) at some length
of the peculiar structure of the polyps of the Tubulariidce, and points out the multifarious development
of the thecaphorcs. But in drawing the bases of his system he makes no attempt to turn these features
to further account.

As a result of searching inquiries, the structure of the polyps in the different genera and
families has turned out not to be quite so homogeneous as it has been generally held. Both in the
construction of the ectoderm and in that of the endoderm differentiations occur, which may be char-
acteristic of greater or smaller groups of species and give us several holds for judging the systems
drawn up for hydroids in the course of time.

Therefore, it will here be appropriate to give a brief synopsis of the more important peculiarities
of anatomy distinguishing the various groups of athecate hydroids, in order to apply them afterwards
to drawing up the system of the group.

The ectoderm, deciding by the disposition of its elements whether the tentacles have to be
claviform or not, has, to some extent, been turned to account as fundameutum divisionis. The clavi-
form shape is particularly due to the accumulation of the stinging cells on the tips of the tentacles,
while the tentacles are filiform when the nematocysts are more equably distributed. A third type of
tentacles, which, as far as is known, is found with all thecaphore hydroids, occurs in the Eudendriidce\

1 Works like that of Poche 1914) I leave out of account. That sort of "zoology" which is based not on study of
the organisms themselves, but only on what may be beaten up from books, here debouches in the construction of airy castles
of complicated svstematics, which does not advance zoological science by a hairbreadth, but only contributes to increasing
the systematic confusion. Between "reguum" and "family" are inserted 34 — thirty four — degrees. It is a matter of regret
that we do not learn how many osculant categories must be placed between "family" and "individual" to give a "full" picture
of nature. But this will suffice to illustrate the scientific value of the work.

S HYDROIDA

here the stinging; cells are arranged in dense transverse belts round the tentacles so as to give these,
when distended, a peculiar transversely striped appearance.

On the ground of filiform and claviform tentacles Kiihn (1913) divides the athecate hydroids
into the two principal groups of Filifera and Capitata. However, we find in the latter group also
instances of filiform tentacles; in the Pennariidce filiform tentacles occur together with claviform ones;
in the Tubulariidce, on the contrary, the claviform tentacles have disappeared, at any rate in the polyps
fully developed. Kiihn (1. c. p. 228), therefore, also makes the reservation that the tentacles are "dauernd
oder in der Jugend geknopft". Embryological studies 011 Corymorpha have, in fact, shown that the
actinula has claviform tentacles (Torrey 1907, Hartlaub 1907). However, this state of things cannot
be generalized as a matter of course to embrace the Tubularia; on the contrary the figures of Allman
(1872) show quite distinctly that the actinula in Tubularia larynx and Tubularia indivisa have filiform
tentacles, and inquiries into the Tubularia regalis in the Trondhjem Fjord have shown no trace of
capitate tentacles during the development of the actinula. Nor do here claviform tentacles occur in
full-grown polyps.

But even though the definition of Kiihn must be characterized as erroneous so far, there is
another criterion showing that his division of groups is correct. A searching study of the very uemato-
cysts, shows, as a matter of fact, that the athecate hydroids fall into two large principal groups, cor-
responding to the Capitata and the Filifera stated by Kiihn.

In the hydroids occur two characteristic principal forms of nematocysts (PI. I, figs 1 — 7). In all
the Capitata we find large oviform or almost wholly spherical nematocysts of the same principal type
as is often mentioned in the Hydra. These large nematocysts are always accumulated on the tips of
the claviform tentacles, as in the Coryue, while on the filiform tentacles of the Tubularia they are
more equably distributed all over the ectoderm of the tentacles. However, these stinging capsules are
also found elsewhere in the ectoderm of polyps, as is the case with Monocorync and Myriothcla. In
the last mentioned form the nematocysts, like those of Millepora, have developed dimorphicly; besides
the typical oviform nematocysts we find here a larger and more slender oval form; in general the
latter nematocysts are outnumbered by the oviform ones, but still they amount to a large percentage
of the total stock of stinging capsules occurring in the animal. In the Millepora this type of nemato-
cysts, judging from the figures in hand, is rather broad.

The rest of the hydroids are distinguished by quite a different type of nematocysts. The pre-
dominant type is a very small, all but rod-shaped nematocyst, particularly occurring in the tentacles,
generally accumulated in belts, vertically on the tentacle axis, giving the tentacles, when wholly
stretched out, a peculiar transversely striped appearance, like that of the tentacles of the Eudendrium
recorded. Concurrently with this typical small nematocyst distinguishing all Filifera sometimes occurs,
finally, a somewhat larger form, as in the Eudendrium and the Sfylasterida. In the Eudendrium
Wrighti we find in the tentacles only small rod-shaped stinging capsules; on the contrary in the
basal whorl of stinging cells of the polyp body of the species in question the capsules are much larger,
though keeping a slenderly oval appearance. It is strange that this large type of the Eudendrium
and the Sfylasteridir should appear almost entirely consistent with the aberrant slenderly oval nemato-
cyst with the Myriothcla. The simultaneous occurrence of the type in so different and so highly

HYDROIDA

organised forms suggests, indeed, that we have before us phenomena of convergency, the cause of
which is at the moment quite inexplicable.

However, not only the ectoderm itself and its elements are of interest to comparative anatomy.
The derivates of the ectoderm are of great importance. In the same way as the ectoderm of
the stem secretes a periderm, we find that with all thecaphore hydroids a chitinous hydrotheca is
secerned by the ectoderm of the polyp. Remarkably enough, a parallel is found also in a single genus
of the athecate hydroids, the Perigonimtts. In this genus the ectoderm of the polyp secretes a
"pseudohydrotheca", a hydrotheca-like, folding periderm -case of a jellied substance surrounding the
basal portion of the polyp up to the tentacle whorl. The first inquiries as to the pseudohydrotheca
have been made by Hadzi (1913 and 1914). The pseudohydrotheca is distinguished from the real
hydrotheca in having no free margin, but being distally firmly connected with the ectoderm of the
polyp so as to be indistinguishable, on a superficial view, when the polyp is wholly distended. On the
contrary, when the polyp is contracted, the pseudohydrotheca is, in general, easily discerned, forming
a richly folded cover round the basal portion. The pseudohydrotheca bears some resemblance to the
genuine hydrotheca by the way in which the polyp is attached to it, the supporting lammella of the
polyp being basally connected with the pseudohydrotheca by a whorl of small chitinous pro-
minences. Similar chitinous prominences are also seen, for instance in Eudendrium, connecting the
soft parts of the stem with the periderm cover; systematically, however, no particular interest can be
attached to them.

Also in the endoderm diversities of great interest are found. The simplest, most homogeneous
shape is represented by the gastric endoderm of Clava (Broch 191 1), forming a homogeneous epithel-
ium for absorbing the nourishment, from the orifice of the mouth to the passage of the polyp into
the stem; almost all of the cells of the gastric endoderm are filled with larger or smaller grains
showing a strong affinity to Delafi eld's haematoxyline ("nutritive cells" and "albumen cells", comp.
Schneider 1902). As to Cory 11 c, the state of things is quite different; here the endoderm in the
portion nearest to the mouth is extremely rich in mucous gland cells, while the digestive cells are
comparatively few in number. In Coryne we must consequently distinguish between the oral
portion secerning mucus and the part of the endoderm of the polyp which is the proper gastric or
digestive portion. The difference between these two endodermal zones appears still more distinctly in
Myriothela\ the glandular cells are here densely concentrated on a small portion near to the mouth,
strongly conspicuous by its clear blueing after being treated with Dela field's luematoxyline; the
other endodermal cellular forms have almost wholly disappeared in the glandular zone with
Myriothela. In Tubularia, on the contrary, the glandular zone has disappeared, so that the endoderm
here by its homogeneous appearance all over the polyp strongly recalls the case of Clava.

A rather different state of things is found in the Bougainvilliida-. Here, indeed, mucous cells,
occur in the oral endoderm of the polyp. But the bulk of the cellular elements in the oral portion as
far as the whorl of the tentacles, is constituted by cells which appear indifferent to the nutritive elements.
All the cells here have small nuclei strongly concentrated, while in the gastric endoderm taking the
nourishment, from the whorl of tentacles and downwards, the nuclei are large, with open chromatine
net-work. This condition of things is still more pronounced in Eudendrium, the mucous cells of

The Ingolf-Expedition. V. 6. 2

IO

HYDROIDA

which, however, are most frequently concentrated in the proboscis, closely to the basis of the tentacles,
where the entrance to the proper gastric cave is found.

Thus there is throughout a typical difference between the Capitata and the Filifcra as to
endodermal matters, though the Clava apparently presents an intermediate form or a form of depar-
ture from which the other types are derivable. Simultaneously the Filifera, as far as can be judged
from the data in hand, bear a typical resemblance to the thecaphore hydroids, and here the parallel
between the Eudendrium and the Campanulariidcs is particularly obvious. Whether this is owing to
a closer affinity or it must be explained only as a phenomenon of convergency, we must at present
leave unanswered, because of our deficient knowledge of the group.

A single family, the T/ibulariida; shows an anatomic peculiarity, as with the species of this family
there occurs a peculiar m'esogloeal formation. At the basis of the large tentacles the endoderm has
developed a thick supporting cushion formed as a ring of mesoglceal tissue of large cells round the polyp.
This leans inwardly on the supporting lamella, and is bounded against the axial endoderm of the tentacles
by a delicate membrane, which in some cases it is rather difficult to point out.

Hollow tentacles occur in two ways. In their original shape they are, as is the case with
Hydra, openly communicating with the gastric cave of the polyp. This state of things, however,
has ceased with most hydroids and cannot be found in any of our northern species. In these, on the
other hand, occasionally occurs, as in Clava multicornis and in Myriothela a central cavity in
the tentacles, at any rate in their basal part. This cavity, however, does not communicate with the
gastric cave of the polyp, but is basally bounded by the unbroken supporting lamella. This central
cavity of the tentacles, as it is represented by well-developed Clava multicornis, might be looked upon
as a primitive condition of things. However, in forms so highly organised as Myriothela, it must
sooner be considered as a secondary phenomenon, which cannot have any direct correspondence with
the primitive condition of things in Hydra.

In Myriothela the tentacles show a peculiar structure, elsewhere unknown in the hydroids.
The matter is more precisely described by J ad er holm (1905). The supporting lamella is in the
thickened distal part of the tentacle transformed into a cushion constructed by delicate radially
placed fibres, showing no cellular structure and densely crowded. They seem to be intended for
strongly stiffening the distal portion of the tentacles and for making the armed outmost portion of
the tentacles larger and more powerful of resistance.

On the ground of the anatomical features stated, and of morphological characters hitherto turned
to account in systematics, is brought about a system which, as far as the athecate hydroid families
are concerned, can be summed up in the following key of determination:

A. No formation of gonophores. Eggs and sperms, developed in the wall of the polyp. The tentacles

- if such ones occur -- hollow, openly communicating with the gastric cave (Sectio Simplicia nov.)
Fam. Hydridce.

B. The generative cells developed in special gonophores.

I. The polyps with large, broadly oval or spherical uematocysts (Sectio Capitata Kuhn).
a. The tentacles of the polyp wholly or in part claviform.

HYDROIDA II

i) The polyp having only one kind of nematocysts. The clavifortn tentacles of simple struc-
ture, having no central cavity and no particularly developed supporting lamella,
a. All tentacles claviform. Fam. Corynidce.

ft. The distal tentacles claviform; proximally a whorl of filiform tentacles. Fam. Pennariida.
2) The polyps, besides having oviform or spherical nematocysts, also provided with slenderly
oval or nearly cylindrical stinging capsules.

a. Without calcareous skeleton. The claviform tentacles having a central cavity, greatly
widened distally, but not openly communicating with the gastric cavity of the polyp.
The supporting lamella, in the outer portion of the tentacles, developed into a thick
radial fibrous supporting tissue. Fam. Myriothelidce.
ft. Colonies with calcareous skeleton. The tentacles of simple structure, having no central
cavity. Fam. Milleporida.
b. All the tentacles of the polyp filiform, arranged in two main circles:

i) The proximal (basal) whorl of tentacles leaning against a well-developed mesoglceal cushion.

The polyps of radial symmetrical structure. Fam. Tubulariidce.
2) The mesoglceal formation at the basis of the proximal whorl of tentacles almost wanting,
owing to radial canals. The structure of the polyps bilaterally symmetric. Fam. Branch-
ioceriauthidic.
II. The nematocysts always only slender, the small ones quite rod-shaped. (Sectio Filifera Kiihn).

a. Colonies without calcareous skeleton.

i) The tentacles irregularly spread all over the polyp, or reducible to a single large tentacle.
The eudoderm not differentiated into oral endoderm and gastric endoderm. Fam. ClavidcE.
2) The tentacles forming a main circle round the polyp. The endoderm differentiated into
an oral endoderm and a gastric endoderm.

a. The polyps fusiform with conically pointed proboscis. Fam. Boiigainvilliidce.
ft. The broad body of the polyp well defined from the stem, and provided with a clavi-
form proboscis placed with a narrow basis on the whorl of the tentacles. Often two
kinds of nematocysts, large ones and small ones. Fam. Eiidcudriidce.

b. Colonies with calcareous skeleton and with two kinds of nematocysts, the large ones being
slenderly oval or nearly cylindric, frequently slightly curved. Fam. Stylasteridcr.

II. Athecate Hydroids of the Northern Atlantic.

Section Capitata Kiihn.
Family Corynidae.

"Hydroids with fusiform or more cylindric polypes, whose oral portion is conically pointed.
The stinging capsules are large, oviform, or almost globular. All the tentacles of the polype are
capitate with the stinging cells mainly concentrated on the thickened distal portion. The structure

2*

12

HYDROIDA

of the tentacles is simple, with no central cavity, and with a thin supporting lamella without any
particular thickening. In the endoderm we must distinguish between an oral portion, abounding
in mucous gland cells, and the gastral portion proper. The colonies develop no calcareous skeleton".

It is questionable, as is also pointed out by Kuhn (1913), whether it is justifiable to maintain
the Corynidac and the Pennariidae as two distinct families. Stechow (1913) states that "das gleich-
zeitige Vorkommen geknopfter und fadenformiger Tentakel ein vorziigliches Merkmal fiir das Bestim-
uieu ist"; simultaneously, however, he ranks the genera Acaulis and Clavatella with the Corynidac,
though, having tentacles both capitate and filiform, they should, from this main characteristic, be
reckoned among the Pennariidae. Also as compared with the Tubulariidae, the limitation of the Pennarii-
dae makes some difficulty. Thus Bonne vie (1899) e. g. classes Hctcrostcphauus among the Tu-
bular iidac in spite of the fact that the species is provided with capitate distal tentacles. Stechow
(1913), on the other hand, as well as Broch (1911), ranks this genus with the Pennariidae. I regret
that I am in lack of material for a more thorough inquiry into the Pennariidae; it is not unlikely
that the anatomical structure of the polypes might afford safer holds for the judging of this group of
hydroids than the merely outward morphological characters.

The Corynidac form a very central group, with which all the other groups of the section of
Capita ta, stated by Kuhn, are likely to have originated. — At the first glance it may appear as if
one of the genera A/ouocorync has got nematocysts heterogeneously developed, so as to show, be-
sides oviform or globular capsules, partly also long, narrowly oval ones. That this is not the case, is ascer-
tained by a careful study of material of Monocoryne gigantea (Bonne vie) collected in the
Trondhjemsfjord. Partly all the nematocysts of this shape are discharged, and partly developmental
stages of other nematocysts than oviform ones are not traceable. It is, therefore, obvious that, in
being discharged, the oviform nematocysts assume a narrowly oval shape. The apparent dimorphism
of the nematocysts would otherwise have been greatly interesting as a connecting link with Myrio-
t/nla, and would have been likely to support the supposition of Bonne vie (1899) of the derivation of
the last-mentioned genus from the Corynidac through Monocoryne. But as a matter of fact, the large
Monocoryne gigantea shows the anatomical structure of the true Corynidac. Swenander (1903) mentions
that its tentacles are coalesced at the basis; this statement, however, only holds good for the ectoderm,
which in several places appears to be stratified; the endoderm, as far as the single tentacles are con-
cerned, continues, wholly surrounded by the ectoderm, to the supporting lamella. Monocoryne gigantea
presents another peculiarity which the inquirers have hitherto obviously failed to notice; the indivi-
duals are hermaphrodite, in a most peculiar way. Not only we find in a single individual sheer female
and sheer male gonophores; but among these also occur several gonophores containing, besides large
ova, also sperms and spermatocytes of all stages. The gonophores of this species are reduced to
cryptomedusoids.

In the internal structure of the polype of the Corynidac our attention is fixed on a great ac-
cumulation of mucous gland cells in the endoderm next to the orifice. Here are densely accumulated
a lot of cells, whose affinity with Delafield's haematoxyline make them very conspicuous on material
well preserved. This concentrated glandular zone is found still more strongly marked in the Myrio-

HYDROIDA

*3

thelidae, whereas in the Tubulariidae it has disappeared. It forms a striking contrast to the proboscis
of the Eudendriidae, the outer oral portion of which is more abounding in indifferent endodermal
cells and more nearly approaching the state of things in the Bougainvilliidae, in which, however, also
the indifferent endodermal cells appear in larger numbers. As is mentioned before, this oral zone is
wanting both in the Clavidac and the Stylastcridac.

The Corynidae, like their near relations the Myriotluiidae, are distinguished by a vigorously-
developed polype musculation, and in connection with this show an astonishing power of changing
appearance and volume. It is easy for them to swallow a comparatively large copepode, and in my
material I have found several shapeless-looking Coryne-polypes which were digesting rather large
crustaceans. Thus they are very greedy animals, frequently feeding on organisms larger than the
polype of normal size. Series of sections show how the food half dissolved also is led direct into the
gonophores and is absorbed by their endodermal spadix. The endodermal cells of the spadix then are
filled with some granulous contents, which are greedily absorbing and tenaciously keeping the haema-
toxyline of Del afield, while they are rather indifferent to both the haematoxyline of Boh me r and
to eosine. However, the cells also contain several eosinophile grains.

Gen. Coryne Gaertner.

"•Corynidae forming colonies, with solitary capitate tentacles spread all over the hydranth. The
colony is formed by the ramification of an upright hydrocaulus, whose tubes do not communicate
through secondary canals. The gonophores are developed on the proximal portion of the polypes".

Many investigators place the species productive of medusae in a separate genus, Syncoryne.
This criterion, however, is of merely biological nature, and thus of less importance to systematists.
And apart from this, it is evident that some species of Coryne produce more strongly reduced eume-
dusoids which are only quite exceptionally detached from the mother colony. The species have not
yet been sufficiently examined. Therefore, it is obvious that, for instance, the species Coryne Loveni
(M. Sars) must have been several times confounded with Coryne Sarsi (Loven). In the medusoid
gonophores of the former species the tentacles are wholly reduced, while Coryne Sarsi has complete
medusoid gonophores with tentacles. The opinion maintained by L. Agassi z (i860) and Hincks
(1868), based on the observations of L. Agassiz (I.e.) and Clark (1865), that some species of Coryne
at one time of their lives produce free-swimming medusae, at other times, on the contrary, sessile
eumedusoids, has not yet been refuted, but, quite the contrary, been strengthened by the observation
of a parallel condition of things in species of Campanit/aria (Giard 1899, Behner 1914). It is
not impossible that Coryne Sarsi shoidd be one of these species of Coryne. In Coryne Loveni the
eumedusoid gonophore has lost its tentacles, and at the same time the development of the generative
cells shows us that the gonophores are not here normally disengaged from the colony. Other species,
such as Coryne Hincksi Bonne vie and Coryne brevicornis Bonne vie, seem to have gonophores
somewhat more reduced, still, however, keeping the medusoid structure strongly defined. These
species, then, exhibit stages forming the transition to Coryne pusilla Gartner with its strongly
reduced styloid gonophores.

IA HYDROIDA

If we, therefore, like Kiihti (1913) and Stechow (1913), separate Syncorync as a genus of its
own, there will be insurmountable difficulties about drawing the limits. If, as is done by Stechow,
the limit is drawn by the production of free-swimming medusae, Coryne Loveni must normally be
omitted from the genus Syncorync, and a species such as Coryne Sarsi will probably have to be reck-
oned sometimes among the Syncorync, at other times, on the contrary, among the Coryne. If, on
the other hand, we follow Kiilin and draw the limits of genera between species with eumedusoid
gonophores and species having gonophores more strongly reduced, it may be greatly questionable
where, for instance, Coryne Hincksi and Coryne brevicornis ought in fact to be placed. In this case
as in others, the more species we learn to know more exactly, the more impossible it proves to draw
the limits of genera on the ground of gonophoral conditions. To this must be added that in all the
species of Coryne or Syncorync the colonies and the polypes are so uniform as to their appearance,
that they cannot with certainty be identified to species or included under one or the other of the two
"genera", if the gonophores are wanting or only little developed. It is, therefore, absurd to insist on
drawing an artificial and arbitrary line of distinction, founding on merely biological phenomena of
adaption.

Coryne Sarsii (Loven) Johnston.

1835 Syncoryna Sarsii, Loven, Bidrag til Kannedomeu af Slagterna Campanularia och Syncoryna

p. 275, pi. 8, fig. 1—6.
1847 Coryne Sarsii, Johnston. A History of the British Zoophytes, p. 43.
Piejii Syncorync Sarsii, Saeniundsson, Bidrag til Kundskaben 0111 de islandske Hydroider II, p. 72.

"The delicately constructed colonies attain to a height of up to 30 mm. The hydrocaulus is
wholly irregularly ramified with no distinct main stem; the branches form acute angles with the stem
or the main branch whence they proceed; both the stems and the branches are almost entirely
smooth with no rings nor wrinkles. The strongly contractile polype, when extended, attains to a
length of up to 1.5 mm., and is then almost wholly filiform ; when contracted, it is oviform or nearly
globular. The numerous capitate tentacles are irregularly distributed over the polype.

The gonophores develop into medusae, which are likely to break away during the greater
part of the generative period of the polype; the medusa bud developes four tentacles. One or two,
more rarely three, gonophores occur simultaneously on the polype".

Material :

Iceland, Reykjavik. Shallow water (associated with small Mytilus).

In all probability, Ssemundsson (1902, 1911) is right in including these very delicately con-
structed colonies under Coryne Sarsii. The occurrence of the species is boreal. But the possibility that
the species is frequently confused with forms nearly related, as yet precludes certain decision as to its
distribution. Coryne Sarsii is recorded from the coasts of Norway, Bohuslan, Denmark, Helgoland,
Great Britain, Iceland, and Northern France. Hartlaub (1905 a) and Jad erholm (1903), though with
some doubt, refer some colonies from Tierra del Fuego and from Patagonia to the same species.

HYDROIDA

15

Coryne Loveni (M. Sars) Bonnevie.

1835 Syncoryna ramosa, Loven, Bidrag til Kannedomen af Slagterna Campanularia och Syncoryna, p.

275, pi. 8, figs. 7—10.
1846 Loveni, M. Sars, Fauna littoralis Norvegiae, p. 2, footnote.

1899 Coryne Loveni, Bonnevie, Norske Nordhavs-Expedition, p. 14.

"The colonies are rather coarsely constructed and attain a height of up to 30 mm. The hydro-
caulus is wholly irregularly ramified and shows no distinct main stem. The branches proceed almost
rectangularly from the stem or the mother branch, but at once curve upwards, forming a very acute
angle or even a parallel with it. The hydrocaulus and the branches are almost entirely smooth, having
only here and there wrinkles slightly indicated. The strongly contractile polype, when extended,

Text-fig A. The occurence of Coryne Loveni in the Northern Atlantic (the hatched coastal Region denotes
a scattered occurence, the totally black parts indicate a common occurence)

attains to a length of nearly 2 mm., and then is slenderly fusiform or nearly cylindric; when contracted
it is oviform, oval, or almost globular. The numerous capitate tentacles are irregularly distributed
all over the polype.

The gonophores develop into eumedusoids, 1.5 mm. long, with no tentacles, normally not break-
ing away; they have four well-developed radial canals and a circular canal. Up to three gonophores
occur on the polype near its base".

Material :

Greenland, Godthaab
Norway, Bjarkoi, Lofoten

litoral (on Aspopkyllum)
litoral (on Fucoideae)

i6

HYDROIDA

Hartlaub (1907) informs us that in his aquaria he has observed a Syncoryne, whose gono-
phores are not set free, though being full-grown medusae with four tentacles well developed; the
generative products are developed in the sessile medusa, which is reduced after having performed her
generative task. Hartlaub refers this form to Coryne (Syncoryne) Loveni M. Sars. This identifica-
tion however, cannot be right; most likely we have here rather in hand individuals of the Coryne
Sursii during the part of the generative period when the medusae are not detached. Through Mr.
C. Dons, conservator at Tromso, I received a very copious material of Coryne Loveni from Bjarkoi,
where the species occurs in abundance on the Fucoidea in the tidal water region. The large number
of individuals examined have most frequently two, more rarely three gonophores, which are developed
into a complete medusa without any tentacles. The four radial canals end in a small enlargement,
which is the only indication of tentacles traceable. The species, accordingly, cannot be identical with
the form recorded by Hartlaub, but agrees very well with the description and the illustration given
by Loven.

Coryne Loveni is earlier known only from the west coast of Scandinavia1. Jaderholm (1909,
taf. 1, fig. 7) gives an excellent drawing of the species collected from Bohuslau; elsewhere it is recorded
from the coast of Norway from Bergen as far as Lofoten, where its occurrence in the northern part
of its habitat is most numerous. Some colonies from Godthaab show us that Coryne Loveni must
also be added to the fauna of Greenland. The species is native to the boreal tidal water zone and
attains to its most luxuriant development in the passage to the regions of the Artie Ocean.

Coryne pusilla Gartner.
1774 Coryne pusilla, Gartner, in Pallas: Spicilegia zoologica vol. 1, fasc. 10, pag. 40; pi. 4, fig. 8.
1893 Syncoryne mirabilis L,evinsen, Meduser, Ctenophorer og Hydroider fra Groulands Vestkyst, p. 150.
1902 Coryne vermicular is, C.fruticosa, Syncoryne exi/nia, Saemundsson, Bidrag til Kundskabeu om de

islandske Hydroider, p. 50.

"The colonies are coarsely constructed, attaining a height of up to 40 mm. The hydrocaulus
is wholly irregularly branched, showing no distinct main stem; the irregularly curved branches are
everywhere densely wrinkled and form almost right angles with the hydrocaulus or with the
mother branch. The strongly contractile polyp, when extended, attains to a length of 2.5 mm., and
is then slender and narrowly fusiform or almost wholly cylindrical; when contracted, it is oviform or
oval. The numerous capitate tentacles are irregularly distributed over the polyp.

The gonophores are globose, showing a styloid structure. There occur 4—8 gonophores, irregu-
larly distributed over the proximal (basal) half of the polyp".

Material:

The Faroe Islands.

Iceland : Grindavik. On littoral algae (labelled Coryne pusilla and C.fruticosa).

Reykjavik. On littoral algae (labelled Syncoryne eximia and Coryne vermicular is).
Greenland (labelled Syncoryne mirabilis).

1 Dr. P. L. Kramp kindly informs me, that Coryne Loveni is abundant in the LitUe Belt.

HYDROIDA

*7

A closer investigation of the living polyps and of their conditions very soon shows us that the
appearance of the polyp is varying very strongly according to its state of contraction. Now it is
stretched at length, assuming approximately the shape of a thin worm, now it is again contracted to
a short, thick lump, very nearly approaching the globular shape. Sometimes the polyp is at the widest
at the base; sometimes it is contracted in this part, so that the largest width appears farther out.
The study of the live polyps thus, in this case as in many others, shows us that many characters
which have been turned to account as criteria of species with the Coelenterata, may be of most doubt-
ful value or even of no importance whatever to classification. In the first place, of course, this is appli-
cable to the various states of contraction, which, in Coryne pusilla, have even led to subdivision into
several species. J ad er holm (1909) thus, on account of difference of shape of the polyp, still
distinguishes Coryne pitsilla and Coryne vermicularis Hi neks; as, however, all other characters wholly

Text-fig. B. The distribution of Coryne pitsilla in the Northern Atlantic.

agree, and the differences put to account as specific characters fall far within the limits of the polyp
movements described above from observation of living individuals, the separation into species cannot
be recognized; Coryne vermicularis forms a synonym of Coryne pitsilla and, in fact, only represents a
phase of the movement of the polyps.

Coryne pitsilla has previously been recorded from the north of France, from Great Britain and
Ireland, from Helgoland, from Denmark, from Bohuslan, from the west coast of Norway, from the
Faroe Islands, and from Iceland (Reykjavik). In my material there also occurs a colony marked
"Greenland?", wrongly determined as Syncoryne mirabilis Agass; the species thus seems to belong to
the fauna of Greenland, but particulars are still missing. The rather numerous Icelandic colonies of
the species are all derived from the south-western point of the island. The species, accordingly, must

The Ingolf-Expedition. V. 6. 3

l8 HYDROIDA

be characterized as southern boreal; it mainly occurs along the coasts of the North Sea and round
the British Isles; how far it advances to the north on the coast of Norway, we do not as yet know
with certainty; but a any rate it does not push forward as far as into the Arctic seas.

Coryne sp. aff. Hincksi Bonnevie.

Material :

"Ingolf" St. 44. 6i°42' Lat. N., g°T,6' Long. W., 545 met. 4.80.

A small colony of young individuals of a species of Coryne is attached to the stalk of a Tu-
bitlaria sp. The hydrocaulus is irregularly wrinkled and attains a height of up to 6 mm. with polyps
1 — 2 mm. long. There occur 4 — 8 small, apparently medusoid, gonophores at the base of the polyp
closely below the tentacles. The tentacles are short. The stolon of the colony is reptant, the stalks
of the polyp are unbranched. On account of the bad state of preservation it is impossible to furnish
a proper design of the individuals.

It is possible that the individuals belong to the species Coryne Hincksi Bonnevie, which
has previously been recorded only from a depth of 100 fathoms near Hammerfest (Bonnevie 1899).

Family Myriothelidae.

"Large solitary hydroid polyps with stratified ectoderm, in which occur two kinds of uemato-
cysts. Besides the typical oviform nematocysts of Capitata are found in somewhat smaller numbers
narrowly oval or nearly cylindrical, rather large nematocysts which are especially frequently occur-
ring in the ectoderm of the gonophores. The tentacles are capitate with a central cavity which does
not communicate with the gastral cavity of the polyp, and which is distally broader. The vigorously
developed distal portion of the tentacles is shored up by a particularly developed portion of the supp-
orting lamella, here showing a fibrillary structure with fibres radiarily arranged. The supporting
lamella is vigorously developed in the wall of the polyp and provided with bilamellae. The endoderm
exhibits a dense circle of mucous glands at the mouth of the animal. No calcareous skeleton is
developed".

The Myriothelidae seem to be nearly related to the Corynidae, and also to the Afilleporidae,
which latter form calcareous skeletons. The last mentioned family presents in its dimorphically
developed nematocysts a strong resemblance to the Myriothelidae. However, only a character as the
peculiarly developed supporting lamella in the thickened distal portion of the tentacles, as well as
the dimorphic development of the nematocysts, justifies the distinction of the Myriothelidae as a parti-
cular family beside the Corynidae. Already Bonnevie (1899) has pointed out the near rela-
tion between Myriothelidae and Corynidae and the bridge between them suggested by the species Mo-
nocorync gigantea (Bonnevie). The arrangement by groups of the tentacles and the attachment of
the gonophores to these groups are very likely to form the base of the development of the blasto-
styles of Myriothela. But on account of the peculiar direction in which the structure of the tentacles

HYDROIDA

19

of the Myriothelidae has developed, we cannot subscribe to the view of Kuhn (1913), reducing the two
families into one. The anatomical structure of the polyps of the two groups differs too much, and to
this difference must be attached a greater importance than the investigators have hitherto been inclined
to do; anatomically the difference between the groups is too great to allow their amalgamation, in
spite of the agreement of the two families as to the endodermal mucous gland portion near the ori-
fice of the polyp.

Hitherto only one genus has been recorded of Myriothelidae.

Gen. Myriothela M. Sars.

''The large solitary polyps have only exceptionally slight indications of hydrocaulus; in general
the base of the polyp is truncate or pointed and provided with rhizoids or filaments of adhesion,
which are in fact transformed tentacles. Both the ectoderm and the endoderm are stratified. The
tentacles are capitate and are irregularly distributed over the polyp and the blastostyles. The gono-
phores are developed on small polyp-like blastostyles attached to the inferior half of the polyp; the
blastostyles bear tentacles on their distal portion".

The genus Myriothela is recorded from the northern seas and from the Antarctic Ocean. The
spread and rare occurrence of the individuals prevents us from deciding whether the genus is in fact
bipolar, as the finds hitherto recorded seem to indicate.

Myriothela phrygia (Fabricius) M. Sars.
1780 Lucernaria phrygia Fabricius, Fauna Groenlandica, Nr. 333, p. 343.
1851 Myriothela arctica M. Sars, Beretning om en zoologisk Reise, p. 134.
1873 — phrygia G. O. Sars, Bidrag til Kundskab om Norges Hydroider, p. 130.

"The capitate or almost cylindrical polyp extended reaches a length of about 400 mm. The
inferior termination of the polyp is truncate, and it is attached to the substratum by tentacle-like fila-
ments of adhesion. Above the portion wearing blastostyles it is studded with strong capitate tentacles;
on the other hand tentacles are wanting on the surface of the polyp between the blastostyles.

The cryptomedusoid gonophores are developed on small polyp-like blastostyles, attached to the
inferior portion of the polyp and wearing capitate tentacles on their outward parts. The female blasto-
style has only one or two fully-developed gonophores at the same time, while the male blastostyles
wear numerous gonophores".

Material:

"Ingoir St. 117. 69*13' N., 8°23'W., depth 1003 fathoms, H- i° C
St. 125. 68°o8'N., i6°o8'W., — 729 — -f- o.8° C.

Myriothela phrygia has an enormous faculty for extension and contraction, and it is likely to
share this faculty with its nearest relatives. A specimen I had the opportunity of observing when it
was brought up by the trawl in the Trondhjemfjord, had stretched its distal portion wearing tentacles
so strongly that the animal was as thin as a thread and measured up to 30 cm. in length; but as

20

HYDROIDA

soon as it was irritated by the preservation fluid, it contracted to a length of only 9 cm., and simultan-
ouslv the diameter of the distal portion of the polyp increased to the measure of 2—3 mm. This
observation shows how little importance is, in fact, to be attached to the absolute measures of the
polyp in the limitation of the species of Myriothela. While the individuals from st. 117 wholly agree
with the earlier descriptions and drawings of the species, the defective specimen from st. 125 (tab. I,
fig. 8) at the first glance differs greatly. The broad, longitudinally strongly contracted basal portion
is studded with blastostyles in a narrow belt, above which the polyp tapers rapidly so as to assume
a conical appearance fairly reminding of the drawing by Bonnevie of Myriothela mitra (1899, tab. IV,
fig. 3). However, a closer examination shows that the distal portion of the polyp has been torn off,

200m .......ftoom •«■•««■ .-..loopm, .._..—...

Text-fig. C. Localities of Myriothela fhrygia in the Northern Atlantic.

and as its trunk above the blastostyles is studded with capitate tentacles, while the polyps of the
species mentioned have no tentacles at all, a mistake of identity is out of the question.

Myriothela phrygia is an arctic deep-sea form, mainly occurring in the icy water at the bottom
of the northern seas. It is recorded from Taimyr (Jaderholm 1908), from the north of Norway, and
from the depths of the ocean between Spitsbergen and Greenland (Bonnevie 1899), besides from the
localities laid down in the map subjoined (Text-fig. C). The original description has been given on
specimens from Greenland, from where, however, we still lack particulars as to localities. "Ingolf"
now adds two new finds in the waters of the Arctic Sea between Iceland and Jan Mayen. On the
whole, the occurrence of the species is scattered; most of the finds are situated in high-arctic regions,
and here the species is seen to occur even at so small a depth as between 12.8 and 14.6 m (Jader-
holm 1908). Therefore, two localities are, indeed, apt to give surprise. One of these localities is recorded

HYDROIDA 21

from the "]\Iichael Sars'1 1902, when the species was found in the warm Atlantic waters to the south of the
Wyville-Thomson-Ridge (Broch 1903). There is in this case a possibility that the animal has been carried
with Arctic currents from northern regions; if so, the currents have conveyed the animal at an earls-
period of life to the new locality, where it has been able to subsist and develop further. The other
locality, in the Trondhjemfjord was previously recorded, and the Trondhjem Museum was in possession
of a defective specimen which was said to have been taken in the fjord ; but particulars were wanting
till the researches of the fjord in 191 1 brought to light, from the depth of 200 m., near Tautra, and
thus in the midst of the Atlantic water layers of the fjord, a well developed female polyp. This find
gives the more surprise, because there is left no opening for the possibility that the specimen should
have been carried to this place from Arctic water layers. Like other Arctic hydroids, such as
Tubularia regalis Boeck, Corymorpha groenlandica (Allmau), and Stegopoma plicatile (G. O. Sars),
Myriothela phrygia thus thrives very well in the region of the Trondhjemfjord which is otherwise-
characterized by Atlantic Lophohelia-reefs. This cannot, however, be turned to account as a proof
against the Arctic character of the species; in the Trondhjemfjord all these species must be looked
on as Arctic relicts.

Family Tubulariidae.

"Hydroids forming colonies, or solitary, with large oviform or globose uematocysts in the ecto-
derm. The tentacles of the full-grown polyp are filiform and simply constructed with no central cavity;
they are arranged in two main circles, a proximal whorl round the broad basal portion of the polyp
and a distal whorl round the mouth. The basal whorl of tentacles is supported by a ring-shaped
mesogloeal cushion round the basal portion of the polyp. The polyps are radially symmetrical. The
supporting lamella shows a very simple structure".

Most authors refer to this family also Branchiocerianthus, which I reckon as the type of a family
of its own, the Branchiocerianthidae. This family is distinguished from the Tubulariidae partly by bilaterally
symmetrical polyps, partly by the peculiar anatomical structure of the polyps. In fact, the structure of the
polyps of the Branchiocerianthidae differs greatly from that of all other hydroids (comp. Stechow 1909).
There occurs a supporting lamella of complicated structure, and the polyp is provided with numerous,
prominent radial canals. They are distinguished from the Tubulariidae also in their inner anatomy by almost
lacking any trace of mesogloeal tissue at the base of the proximal whorl of tentacles, owing to the
radial canals. These points of difference are, indeed, of such importance that they fully justify the sepa-
ration of Branchiocerianthus into a family of its own, the Branchiocerianthidae beside the Tubulariidae.

Kiihn (1913) divides the Tubulariidae into two subfamilies, Tubulariinae and Corytnorphinae.
The former he defines by the characters "Koloniebildend, Periderm gut entwickelt", while the latter
is defined as "Solitar, Periderm hautig oder riickgebildet, Wurzelhaare". To this is to be observed that
a species as Tubularia cornucopia Bonne vie is a typical Tubularia in spite of its forming no colonies.
The filamentary appendages of Corymorpha must be compared with similar phenomena in Myriothela,
some species of which have rhizoids, while others such as Myriothela Cocksi (Vigurs), attach thems-
elves by a plateformed perisarc; when this is considered as nothing else or no more than a criterion

22 HYDROIDA

of species with Myriothela, there tells indeed little in favour of raising it to a distinguishing mark
between two subfamilies of the Tubulariidae. As far as finally the development of the periderm is
concerned, this is a gradual character showing many transitions, to which no importance can be
attached as a distinguishing mark between two subfamilies.

Gen. Tubularia Linne.

"Hydroids most frequently forming colonies, the hydrocaulus being surrounded by a stiff and
chitinous perisarc. The polyps are radially symmetrical, having two main circles of tentacles, a proximal
(basal) whorl of long tentacles leaning on a mesogloeal ring in the trunk of the polyp, and a distal
whorl with short tentacles round the mouth. The tentacles are also in the actinula filiform.1 The gono-
phores are generally borne on blastostyles; the gonangia spring from the trunk of the polyp between
the two whorls of the tentacles".

The gonophores are, in this genus as in most other genera, sometimes medusoid, sometimes
more or less reduced. The species producing free medusae have been grouped by many authors as a
genus of their own, Hybocodon. In this case as in others, the question then arises where the line is to
be drawn. While in species as Tubularia pulcher (Ssemundsson) the medusa breaks away, the fully
developed medusoid gonophore in Tubularia rcgalis Boeck, as far as is known to us, never voluntar-
ily relinquishes its sessile existence. If we follow Kulin (1913), as might seem right, we get into a
dilemma, having to refer the female of Tubularia regalis to Hybocodon, while the male, having erypto-
medusoid gonophores (Broch 1915), must remain in the genus Tubularia. Only this should be suffi-
cient to show the error of turning the organisation of the gonophores to account as fundamentum
divisionis. No doubt, it is wrong to set up Hybocodon as a particular genus of hydroids, and the same
is certainly the case with the. genus Anliscus set up by Ssemundsson (1899), the medusae of which
as we are going to see, are scarcely particularly distinguished as compared to the other Hybocodon-
medusae.

Tubularia pulcher (SEemundsson).
1899 Aiiliscus pulcher Ssemundsson, Zoologiske Meddelelser fra Island, p. 425, Tab. IV.

"Colonies, the hydrocauli of which are up to 50 mm. long, uubranched, and separated down to
the reptant hydrorhiza. The stalk is covered with a brown perisarc, which is thick at the base, but
upwards against the polyp narrowing periodically and at distinct intervals, so that the stalk gets an
appearance approximately articulate; the spaces between the transverse striae, brought about in this
way, attain their greatest length in the middle part of the stalk, being here 13 mm. long. The upper
portion of the stalk is provided with a thin perisarc, widening funnel-shapedly into a thin collar
under the polyp. The polyp is fitted out with a basal circle of 24 — 30 tentacles, about 5 mm. long;
the distal tentacles, about 30, are placed, densely crowded, in a narrow belt, consisting of several rows,
round the orifice, and attain a length of a little more than 1 mm.

The gonophores develop into free Hybocodou-medusae with gemmation on the bulb of the

1 The tentacles of the actinula may be swollen at their tips (comp. All in a n 1S72) but never show the dense accumula-
tion of stinging cells here, which is so characteristic in the truly capitate tentacles of the section Capitata.

HYDROIDA 23

large tentacle; there are four radial canals. The bell exhibits five exumbrellary stinging cell stripes.
The gonophores are developed on eight blastostyles faintly branched, a little more than 1 mm. long".

Material :

Iceland, Reykjavik. Near the shore (1 specimen).

The specimen in hand is one of the original specimens investigated by Ssemundsson (1899).
It is an individual with hydrocanlus 30 mm. high. The polyp is fitted out with 25 proximal tentacles,
5 mm. long, and S blastostyles a little branched, about 1 mm. long. A closer inquiry of the gonophores
gives a picture somewhat different from that drawn from the explanation of Saemundsson. In the
first place the umbrella of the medusa is not quite symmetrical, but somewhat oblique, as in Hyboco-
don prolifer L. Agassiz. At first only one tentacle, not two, is developed on the large tentacle bulb
(Tab. II, fig. 16); the "corpora acuminata et duo ovata", mentioned by Ssemu ndsson as springing
from the tentacle bulb, are all gems of medusae; none of them can be made out as "initium tentacu-
lorum novorum" belonging to the original medusa. Wherever at the first glance two tentacles seem
to occur on the bulb, a closer research will show that one of them in fact belongs to the bud of a
new medusa on the bulb of the gouophore. Therefore, we have to concur in the opinion of Hart-
laub (1907) and subscribe to his explanation of the apparent occurrence of two tentacles with Hybo-
codon prolifer as satisfactory for the species in hand, that "bei der Knospung von Hybocodon der Ten-
takel in der Entwickelung stark voraneilt und schon fertig seiu kann, wenn der dazu gehorige Me-
dusenkorper uoch nicht deutlich in die Erscheiuuug getreten ist".

The conditions of gonophores described show a much nearer relationship to Tubularia [Hybo-
codon) Christ inac Hartlaub (= Tubularia prolifer Bonne vie 1899). Hartlaub's drawing of Hybo-
codon Christinac (1907, fig. 98) is, according to the statements cited, easily reconcilable to the figure a
little more skeletonlike given by Ssemundsson (1899, tab- *V, fig. 3). Nor is the difference between
the polyps very great; Bonne vie (1899) states for her specimen 14 proximal tentacles, about 10 mm.
long, while the species stated by Ssemundsson is said to have 24 — 30. It is a matter of regret that
we only know the length of the proximal tentacles of the specimen in hand. But on account of the
great contractility of the tentacles, no particular systematical importance can be attached to their
length, and as far as the difference of numbers of the proximal tentacles is concerned, we see in other
Tubulariidae within easy reach such a variety that the difference quoted by itself cannot justify any se-
paration of species. When Tubularia Christinac is nevertheless maintained as a separate species beside
Tubularia pu/cher, it is in the first place owing to the express declaration of Bonnevie (1899) that
her specimen has no collar under the hydranth ; such a collar is, on the other hand, strongly developed
in Tubularia pulchcr, though at the first glance it may seem very little distinctive on material preserved.1

Hartlaub (1907) holds that the medusa is identical with the medusa drawn by Steenstrup
(1842), Corync fritii/ar/a, and much is speaking in favour of the correctness of this supposition. On the
other hand, the polyp described by Steenstrup, in the same place and by the same name, cannot
be identified. It may be that it really is a Corync; some features are even suggestive of Corync Lo-
veni M. Sars; but the only thing the drawing shows us with full certainty, is that the polyp is no

1 The original specimen of Bonnevies Tubularia prolifer was wanting in the museum of the Kristiania university.

24

HYDROIDA

Tubularia, and that its medusoid gonopliores, if they are rightly perceived, cannot develop into medusae
of the Hybocodon type.

The only locality from which Tubularia pulcher is recorded with certainty, is the shore near
Reykjavik, Iceland, where it has been found only once.

Tubularia indivisa Linne.
1758 Tubularia indivisa Linne, Systema Naturae, Ed. 10, p. 803.
1899 obliqua + T. indivisa Bonne vie, Norske Nordhavs-Expeditiou, p. 24.

"Colonies, whose long dark brown-coloured hydrocauli are, in the lower part, twisted together.
The stems are covered with a vigorous jDerisarc, but show no rings nor wrinkles. No collar is formed
below the polyp. The polyp has a basal whorl of 20 to 30 tentacles up to 20 mm. long; the distal
tentacles are up to 3 mm. long and densely crowded round the orifice in a whorl consisting of
several rows.

The female gonopliores are eumedusoid with four rudimentary radial canals, one of which
(the shortest) is often slightly indicated even in the gonophore fully developed. The gonophore
has, near the apex, a tentacle-like bulging, obliquely situated. The male gonophores are crypto-
medusoid and almost wholly globular, not oval. The gonopliores are born upon up to 10 blasto-
styles, which attain a length of 10 mm. The actinula-larvae, when set free, wear filiform
tentacles".

Material :

"Ingolf" St. 31, 66°35'N., 55°54'W.; depth 88 metres i,6° C. (Davis's Straits).

— St. 87, 65°o2'3 N., 23°56'2W.; depth no metres (West-Iceland).
Greenland: Davis's Strait (without further data).

Egede's Minde ( — — ).

Iceland: Brede Bugt 65°i2' N., 23°28' W., depth 36 fathoms.

— Grindavik littoral.

— Skagestrand depth 60 fathoms.
Vestmanno littoral.

The Faroe Islands (without further data).

The North Sea: the West side of large Fishing bank 57°7' N., 2°4o' E., depth 37 fathoms.

Swenander (1903) has pointed out that Tubularia obliqua Bonne vie (1899) is based on female
individuals of Tubularia indivisa; thus in the very external characters of the gonopliores this species
presents a peculiar sexual dimorphism, and inquiries into the conditions of the gonopliores (Broch
191 5) have made good that this sexual dimorphism is a radical one, the female gonopliores being
eumedusoid, the male ones on the contrary cryptomedusoid. — Tubularia indivisa is very easily con-
founded with the following species, Tubularia rcgalis, particularly when only male individuals are in
hand for examination. In this case only the somewhat different shape of the gonophores makes it
possible to refer with certainty the individuals to one species or the other, the male gonophore of

HYDROIDA

25

Tubularia indivisa being globular, and accordingly broadly rounded in the distal part, while that of
Tubularia regalis is oval and showing an attempt to be pointed in the distal part.

Tubularia indivisa has a very wide distribution. Its main occurrence in the boreal seas is bound
to the middle and deeper parts of the littoral region and to the upper part of the deep sea region.
From the cold area we find the species but once recorded, by Grieg (1914). After the examination
of his specimens I cannot confirm this record; the specimens consisting only of hydrocauli without
polyps, more probably belong to another species of Tubularia inhabiting the deep sea.

To judge from literature, Tubularia indivisa penetrates rather far into the shallower parts of
the Arctic regions, where it is recorded even from the New Siberia Islands (Jaderholm 1908). How-
ever, as appears from what is stated above, there is a possibility that some of the Arctic individuals

Text-fig. D. The distribution of Tubularia indivisa in the Northern Atlantic.

are in fact to be referred to Tubularia regalis. — The species also penetrates far towards the south.
It is recorded by Fewkes (1881) even from the Caribbean Sea, by A 11 man (1877) from between Cuba
and Florida, and by Billard (1906) from the west coast of Africa. As Tubularia indivisa is recorded
at the same time both from the East and the West coast of North America, it must be characterized
as a circumpolar or rather "circumborear (Nordgaard 1912) species.

Tubularia regalis Boeck.
i860 Tubularia regalis Boeck, Videnskabsselskabets Forhandlitiger for 1859.
1899 - T. variabilis Bonuevie, Norske Nordhavs-Expeditiou, p. 24.

Colonies whose long, dark-brown-coloured hydrocauli are in the lower parts twisted together.
The stem is covered with a vigorous periderm, but shows no rings nor wrinkles. No collar is formed

The Ingolf-Expedition. V. 6. 4

26

HYDROIDA

below the polyp. The polyp wears a basal whorl of 20 — 35 tentacles up to 40 mm. long; the distal
tentacles, up to 3 mm. long, are densely crowded round the orifice in a whorl consisting of several rows.
The female gonophores are eumedusoid with 3 — 6 external longitudinal ribs and as many
corresponding radial canals. The male gonophores are cryptomedusoid and oval, often with an attempt
to be pointed in the distal part. The gonophores are born upon up to 20 blastostyles, which attain a
length of 35 mm. The actinula larvae, when deliberated, wear filiform tentacles.

Material :

Between the Faroe Islands and the Shetlauds, depth 505 fathoms.

Tubularia regalis presents so many points of resemblance to Titbularia indivisa that the risk of
confounding the two species is very easily incurred. As a general rule, the full-grown polyps of Tu-

20om. 600m. ._ 100a m. 3000m.

Text-fig. E. The occurence of Tubularia regalis in the Northern Atlantic.

bularia regalis are larger than those of Tubularia indivisa. But this is not the case in younger
individuals of Tubularia regalis, in which consequently the only certain distinguishing marks are pre-
sented by the gonophores. The gonophores, indeed, are typical enough in the female individuals, but
are not very conspicuous in the male ones, especially at earlier stages. The male gonophores of Tu-
bularia regalis are oval, while those of Tubularia indivisa are globular. It is evident from the diag-
nosis of the species, that also Tubularia regalis presents a strong sexual dimorphism. The first who
got aware of this fact, was Swenauder (1903), who accordingly pointed out that the female had been
described as a different species Tubularia. variabilis Bonne vie.

Tubularia regalis is a form of true Arctic character, particularly occurring in the deeper
parts of the cold area. In the seas far towards the north it rises to shallower parts, and it is, for instance,

HYDROIDA

27

recorded from Spitsbergen at the depth of only 38 m. (Broch 1909). Evidence of its occurrence
in the Kara Sea is still wanting. From this locality a specimen is in hand, determined by Bergh
(18S7) as Tabula via regalis. As a matter of fact, the specimen is a Corymorpha, probably a Cory-
morpha glacialis M. Sars. — A remarkable exception to the habitat stated is formed by the frequent
occurrence of the species in the Trondhjem Fjord, where it is found in abundance on the Lophohrlia-
reefs. In spite of the luxuriant development which it attains in the Trondhjem Fjord, it must probably,
like Corymorpha groenlandica (Allman), Myriothela fhrygia (Fabricius), and Stegopoma plicatile
(G. O. Sars), be accounted for as an arctic relict in this locality.

Tubularia larynx Ellis et Solauder.
1786 Tubularia larynx, Ellis et Solauder, The Natural History of Many Curious and Uncommon

Zoophytes, p. 31.
1864 liu 111 His, Allman, Notes on Hydroida, p. 57 and 60.

Colonies whose long polyp stems, generally unbranched and irregularly curved, are separated
quite down to the tangled network of basal tubes. The stems are covered with a fairly vigorous, but
colourless perisarc, which is irregularly wrinkled or more rarely quite smooth. The polyp wears a
basal whorl of up to 25 tentacles, attaining a length of 8 mm.; the numerous distal tentacles, 2 or 3
mm. long, are densely crowded round the orifice in a whorl consisting of several rows.

The gonophores are eumedusoid, without radial canals, but with a rudimentary circular canal ;
they are most frequently provided with three rudimentary tentacles. The gonophores are supported by
6 — 12 short blastostyles, which may be erect or hanging. The actiuula larvae, when deliberated, show
filiform tentacles.

Material:

Iceland: Reykjavik.

Gustsey depth 4 fatli.

Keflavik — 15—16 —

Faxebugt three miles N 37 E Keflavik 19,5 —

Off Havnefjord 25

Stykkisholm — 20—30 —

Skagi — 40 m.

Vestman Islands — ■ 28 fath.

The Faroe Islands : Andefjord — 16—23

The North Sea 6o°35' N., i°5o' W 50

The synonymy of the varying species has been thoroughly accounted for by Fenchel (1905).
He points out that, as is also maintained by Bonuevie (1899) and by Swenander (1903), Tubularia
coronata Abildgaard must be subsumed under Tubularia larynx. On the other hand, it is not plainly
seen whether he regards Tubularia /luiuilis Allman to be a peculiar species. On a closer exami-
nation, indeed, the characters pointed out by Bonne vie (1899) as distinguishing marks, prove to
be of no particular systematic importance. The wrinkling of the stem is strongly varying from

4*

28

HYDROIDA

one individual to another in a larger colony, and individuals with quite smooth stems are not seldom
observed in colonies which are otherwise typical Tubularia larynx. The dimensions of Tubularia humilis
wholly agree with those of young colonies of Tubularia larynx, and the numbers stated as characteristics
stand far within the range of variability known in this species. Then only remains the condition of
the blastostyles, which should be erect in Tubularia humilis, but hanging in Tubularia larynx. An
examination, however, of living material will show that only in rare cases the blastostyles of Tubularia
larynx can be described as hanging (comp. Broch 1911); on the contrary they are generally borne in a
rather erect position, particularly when not yet very large. Thus also this criterion proves to fail,
and consequently we are forced to consider Tubularia humilis as a synonyme of Tubularia larynx.

Tubularia larynx is an entirely boreal species, which has its main occurrence in the zone of the

Text-fig. F. The distribution of Tubularia larynx in the Northern Atlantic.

laminaria and the red algae. Towards the south it enters into the Mediterranean, and towards the
north it penetrates as far as Nova Zembla, and seems still to occur at Spitzbergeu. On the south-
western coasts of Iceland it is very frequent, and it is also found on the east coast of North America.
It is to be wondered that the species has not yet been met with at Greenland.

Tubularia sp. iudet.
Stems of Tubularia of the type indivisa-regalis are in hand from the following localities:
"Ingolf" St. 8. 63°56' N, z\°\d W., depth 136 fathoms, + 6°o C.
35. 65°i6' - 550o5' - 362 + 3°6 -

- 36. 6i°5o' - 56°21' " x435 + l05 -

HYDROIDA

29

"Ingolf" St. 40. 62°oo' N., 2i°36' W., depth S45 fathoms, + 3^ C.

- 86. 65°o3'6 - 23°47'6 - 76 ?

- 87. 65°o3'2 - 23°56'2 - — no ?

- 106. 65°34' - 8°54' - 447 - o°6 C.

- 127. 66°33' - 20*05' - - 44 + 5°6 -

- 143. 62°58' - 7°o9' - 388 - o°4 -
Of a type like that of Tubular ia cornucopia Bo nne vie from the localities:

"Ingolf St. 11. 64°34' N., 3i°i2' W., depth 1300 fathoms, + i°6 C.

- 18. 6i°44' - 3o°29' - 1135 + 3°o -

"4T

Gen. Corymorpha M. Sars.

Solitary hydroids, whose contractile hydrocaulus is surrounded by a flexible, thin, and membran-
aceous perisarc. The hydrocaulus is attached to the substratum by numerous rhizoids. The structure
of the polyp is radially symmetrical with two main whorls of tentacles, a proximal or basal whorl
of long tentacles supported by a mesogloeal ring in the polyp body, and a distal whorl of short ten-
tacles round the orifice. In the full-grown polyp all the tentacles are filiform; in the actinula
larva at any rate the distal (oral) tentacles may be capitate. The gonophores are generally supported
by blastostyles; the gonangia arise from the body of the polyp between the tentacle whorls.

As early as 1909 I stated this limitation of the genus, grouping at the same time the species,
on the ground of gonophoral matters, in four subgenera. However, I suggested that, as to the rela-
tions between the two subgenera Monocaulus and Lampra, a closer inquiry was wanting. As a matter
of fact, one of the species stated by A lima u (1876) Monocaulus grocnlandica really proves to be
identical with two of the species of La/upra stated by Bonuevie (1899). Also the other northern spe-
cies of Monocaulus has met a peculiar fate, being first ranked by Allmau (1872) within his genus as
Monocaulus glacialis (M. Sars), and afterwards (1876), after the examination of some specimens from
the museum of Copenhagen, described as a new species, Amalthaca islandica All ma 11.

These matters, indeed, throw a glaring light on the uiimaintainability of the subdivision into
so-called "genera" to which Corymorpha has been the subject. At the first glance it is a matter of sur-
prise that Stechow (1913) still tries to maintain the old genera. Indeed, in zoology more considera-
tion must be given to the observations made on living individuals than has hitherto been done. Thus
the two main criteria turned to account by Stechow (1912) for the purpose of distinguishing Cory-
morpha Sarsii Steenstrup (1854) and Corymorpha vardocnsis Loman (1889) testify to the fact that
matters of contraction are still allowed to play a prominent part as to the limitation of species. By
the observation of a living Corymorpha it will soon be ascertained that, by extension and contraction
of the lower parts of the polyp and of the upper sections of the stem, the same polyp will show now
a more emphatic distinction from its stem, now a smoother transition into it. The points of difference de-
lineated by Stechow (191 2, Taf. 12, Fig. 2 and 3) are, in this respect, not so great as those which
may be observed in a single individual while alive. The other main character, that the spadix of the

30 HYDROIDA

gonophore of Corymorpha Sarsii is "fast inimer" projecting from the umbrellar cavity, while this is
"fast nie" the case with Corymorpha vardoensis, is in the first place very vagne, and secondly depend-
ent partly on the various contraction of the umbrella, partly on the sex and the degree of maturity
of the gonophore. On the whole there can be no doubt that the description of Corymorpha vardoensis
is based on an individual of Corymorpha Sarsii.

I have entered on this subject because Stechow (1912, 1913) puts together the species menti-
oned into a genus of their own, Amalthaed. The genus was first established by O. Schmidt (1854) for the
species Amaltliaca uvifera O. Schmidt, which is likely to be identical with Corymorpha Sarsii. Item-
braces the species of Corymorpha whose gonophores develop into complete medusae, but, after all, not
breaking away, whereas the species whose medusae are normally breaking away, are gathered in the
genus more narrowly limited, Corymorpha. It is evident,however, that the medusa of Amalthaea excep-
tionally breaks away and then leads a wretched life, unfit as it is for free existence on account of
possessing a too small umbrella, the greater part of which is, into the bargain, occupied by the enormous
spadix with mature generative cells. The medusa strongly reduced, further, shows so near a rela-
tionship to the medusa of Corymorpha nutans M. Sars that a systematist of medusae so skilful and
discerning as Hartlaub (1907) decides on only placing it in a subgenus of the medusoid genus
Corymorpha. The classification afterwards maintained by Mayer (1910), who distinguishes the two
groups of medusae as peculiar genera and even places them in quite different places in his syn-
opsis, as Amalthaea and Stcaistrupia, only proves that he has failed to notice the excellent drawing
by M. Sars (1877), which shows us in fact, that the female gonophore, when fully developed, is often
an entirely typical Stccnstrupia, though one of the main tentacles is not quite so large as in Cory-
morpha nutans. The figures delineated by Sars wholly agree with the facts observed in living
individuals, and make good the correctness of Hartlaub's view of division, giving the right place
to affinity and biology. But where is then the fundameutum divisiouis adaptable for the purpose of
classifying the Corymo'rpha-\ike species of polyps into separate genera?

From Amalthaea to Monocaulus glacialis there is, indeed, a very short step; all the difference,
as a matter of fact, is to be found in the gonophore, also here eumedusoid, being even somewhat more
reduced, as the tentacles, the special organs of the umbrellar margin, are entirely wanting. The con-
formity of the polyps is obvious; the gonophores of both species are eumedusoid and normally sessile;
the difference is accordingly too little for a separation of genera.

Then only remains the group of Lampra, whose gonophores are cryptomedusoid. A generic
separation between, for instance, the species of Lampra and Corymorpha {Monocaulus) glacialis, will,
as I have recently pointed out (1915), correspond to a generic separation between o* and $ in Tubu-
lar ia indivisa Linne or Tubularia regalis Boeck. A particular argumentation of the unnaturaluess
of this limitation is hardly required. But then it is obvious, as a matter of course, that a generic
separation of the species of Lampra and the other species of Corymorpha cannot be maintained. Also
the species of Lampra must be ranked within the genus Corymorpha.

HYDROIDA

31

Corymorpha nutans M. Sars.

1835 Corymorpha nutans, M. Sars, Beskrivelser og Iagttagelser p. 7, PI. 1, Fig. 3.

The hydrocaulus, when extended, attains a height of 100 mm. It is broad at the basis, attached
to the substratum by numerous rhizoids, and tapering upwards till it reaches its least breadth closely
below the polyp. The basis of the polyp is broad and surrounded by a proximal whorl consisting of
up to 50 tentacles, which, when extended, attain a length of 30 mm. The distal tentacles are small
and placed round the orifice in a main whorl composed of several irregular circles quite closely set.

The gouophores are developed into free medusae with four radial canals, one well-developed
tentacle and three rudimentary ones. The gouophores are developed on 15 — 20 blastostyles, arising

Zoom. __ „ _6oom. 1000 m. 2000m,

Text-fig. G. The habitat of Corymorpha nutans in the Northern Atlantic.
(In the hatched regions the Htterature denotes a scattered, allthough common occurence).

closely above the proximal whorl of tentacles. The blastostyles bear small alternating branches, each
provided with a large number of gouophores.

Material :

Iceland, 16 minutes N. W. Akraues, depth 26 — 30 fathoms (a couple of young polyps).

The occurrence of the species is typically boreal. It is indigenous to the middle parts of the
littoral region. Towards the north it goes along the coast of Norway as far as L,ofoten and towards
the south it penetrates to the northern parts of France. The species is recorded by Jaderholm (1909)
from Matotschkin Schar (Nova Zembla) at the depth of between 2 and 5 fathoms. This find is most
peculiar and mysterious. Corymorpha nutans occurs not rarely in the North Sea, and I think Hart-
laub (1907) is right in supposing the specimen from the North Sea recorded by me (1905I as a Cory-

32

HYDROIDA

morpha, to be in fact a young colony of Corymorpha nutans. Remarkably enough, the species has
not yet been met with at the Faroe Islands; but it has been found several times on the west side of
Iceland. At Greenland it is not likely to occur; nor has the species as yet been recorded from this
locality.

Corymorpha glacialis M. Sars.

1859 Corymorpha glacialis, M. Sars, Ora Ammeslsegten Corymorpha.

1872 Monocaulus glacialis, Allman, A Monograph of the Gymnoblastic or Tubularian Hydroids,

P- 396-
1876 Amaltlura islandica, Allman, Diagnoses of new Genera and Species of Hydroida, p. 256, PL

IX Fig. 5-6.

? 1887 Tubularia rcgalis, Bergh, Goplepolyper fra Kara-Havet.

Nee 1893 Amalthwa islandica, Levinsen, Meduser, Ctenophorer og Hydroider fra Gronlands Vestkyst,

p. 151.

The hydrocaulus, when extended, attains a height of 100 mm. It is wide at the base, where

it is attached to the substratum by numerous rhizoids, and is gradually tapering upwards till closely

below the polyp where its width reaches its minimum. The polyp has a broad base, surrounded by a

whorl of up to 50 tentacles, which, when extended, attain a length of 30 mm. The distal tentacles are

small and numerous, placed round the orifice in a main whorl formed by several irregular and closely

set circles.

The gonophores are eumedusoid, with four radial canals, but without rudiments of tentacles.

They are sessile. The gonophores are scattered all over the surface of 30—35 unbranched blastostyles,

the oldest and most developed ones at the apex of the blastostyle.

Material :

Iceland, Ofjord (without particular data). Original specimen of A ma Ithaca islandica.
?The Kara Sea ("Dijmphna". Particular data are wanting). Labelled Tubularia rcgal/s.

The original specimen in hand of Amalthaca islandica Allman (1876) proves as clearly as de-
sirable that this species is wholly identical with Corymorpha glacialis. Allman, certainly, states that
the gonophores of the species are provided with four short tentacles, which are also, in his rather
skeletonlike drawings, delineated as rather considerable formations. But in the original specimen can
only in some straggling gonophores be pointed out some accidental wrinkles, which, when acting in
good will, we may consider as the origin of the rudimentary tentacles stated. Other divergencies from
the typical Corymorpha glacialis are, on the whole, not traceable.

A specimen from the Kara Sea has been identified by Bergh (1887) as Tubularia rcgalis Boeck.
The specimen is an unquestionable Corymorpha and no Tubularia; indeed, everything suggests that
it is a Corymorpha glacialis, but the state of preservation impedes a safe identification.

According to the particulars in hand Corymorpha glacialis is indigenous mainly to Arctic wa-
ters. It has been recorded from the Varanger fjord (M. Sars 1859), from Nova Zembla (Maren-
zeller 1877), and from Spitsbergen (Broch 1909). But the species also penetrates into wanner water

HYDROIDA

33

layers, as is seen (Text-fig. H) from the finds to the north east of the Faroe Islands and on the south
east coast of Iceland (Broch 1903). As new localities must be added Northern Iceland (0fjord). On
the other hand, the specimens from Davis Strait, recorded by Levinsen (1893) as Amallhaea islandica,
prove to belong to Corymorpha groenlandica (Allman).

Corymorpha groenlandica (Allman) Broch.
1876. Monocaulus groenlandica, Allman, Diagnoses Jof new Genera and Species of Hydroida, p. 257,

PI. IX, Fig. 7—8.
1893. Amalthaa islandica -\- Monocaulus groenlandica, Levinsen, Meduser, Ctenophorer og Hydroider

fra Gronlands Vestkyst, p. 151.

20om. 600m. ._ 1000m. 2000m.

Text-fig. H. Finds of Corymorpha glacialis in the Northern Atlantic.

1899 Lan/pra atlautica -f Lampra purpurea, Bonnevie, Norske Nordhavs-Expeditiou, p. 20, Tab. II

Fig. 4, Tab. Ill Fig. 1.
I903 _ socia, Swenander, Uber die athecaten Hydroiden des Drontheimsfjordes, p. 6, Taf.

Fig- 1—3-
ICpg — arctica, Jaderholm, Hydroiden, p. 41, Taf. I Fig. 9—10.
1909 Corymorpha spitzbergensis, Broch, Die Hydroiden der arktischen Meere, p. 140.
101$ — groenlandica, Broch, Hydroiduntersuchungen IV, p. n.

The hydrocaulus, when extended, attains a height of 100 mm; it is widest at the base, where
it is attached to the substratum by numerous rhizoids, and is gradually tapering upwards till close
below the polyp where the width reaches its minimum. The polyp has a wide base, surrounded by

The Ingolf-Expedition. V. 6. -J

34

HYDROIDA

a basal whorl of up to 37 tentacles, which, when extended, attain a length of 40 mm. The distal ten-
tacles, when extended, attain a length of 9 mm; they are placed in large numbers round the mouth
in a main whorl formed by two or more irregular and closely set circles.

The gonophores are cryptomedusoid and globular ($) or sub-oval (J1), often somewhat tapering
distally, but without any rudiments of tentacles. The gonophores are supported by unbranched and
strongly contractile blastostyles, which, when extended, attain a length of 40 mm. The gonophores
first ripen at the apex of the blastostyle. As many as 32 blastostyles may occur, but, in general, the
number is much smaller; the blastostyles arise close above the basal whorl of tentacles.

Material:

"Ingolf" St. 102. 66°23' N., io°26' W., depth 750 fathoms, -~ o°o, C.

- 107. 65°33' - io°28' - -492-^ 0°3 -

- 139- 63°36' - 7°3°' - — 702 - -=- o°6 -

Greenland: Godthaab (no particulars) [A 11m an' s original specimen of Monocaulus groenlandica\

Davis Strait, depth 100 fathoms [labelled Amalthaea islandica\.
Iceland: 66°o2' N., n°o5' W.

5 miles east of Seydisfjord ; depth 435 fathoms.

The fairly well preserved specimens of the material recently collected show the following cha-
racters (all the measurements are given in mm).

Nr.

Finds

Height of
Hydro-
caulus

Blastostyles

Proximal Tentacles

Distal Tentacles

Observations

Number

Length

Number

Length

Arrangement

Length

1

"Ingolf St. 139

90

14

5

?

?

in several close circles

2

Hydrocaulus strongly-
extended

2

"Ingolf St. 139

60

15

1—3

?

?

in several close circles

2

Blastostyles very strong-
ly contracted

3

"Ingolf St. 107

57

13

3-5

26

25

in a double circle formed by
alternating displacement

1-5

4

"Ingolf St. 102

45

IO

5

23

up to 24

in several close circles

1-5

5

"Ingolf St. 102

4i

8

5

25

24

in a double row formed by
alternating displacement

2

6

Davis Strait

40

20

7

24

25

in several close circles

5

7

"Ingolf St. 107

?

10

6—13

21

3°

in three irregular rows formed
by alternating displacement

1-5

Hydrocaulus more than
50 mm high

8

"Ingolf St. 102

?

9

4

28

up to 23

in several close circles

2

9

"Ingolf St. 107

?
?

16

3-4

24

22

in a double row formed by
alternating displacement

2-5

10

66°2'N.ii0O5'W.

2S

5-18

22

25-30

?

?

Blastostyles placed alt-
ernatingly ; attempt
at forming two rows

11

"Ingolf" St. 107

?

14

4

18

l8

in three irregular rows formed
by alternating displacement

2

HYDROIDA

35

The species, which is widely distributed in the deeper parts of the cold area, has been found by
several expeditions, and has formed the base of the genus Lampra stated by Bonne vie (1898, 1899).
I have already in works earlier published pointed out that, for several reasons, this genus cannot be
maintained. In the first place, the name of Lampra had already been applied to a subgenus of the
beetle family Buprestidae, and should, therefore, disappear among the hydroids, according to the rules
of nomenclature internationally adopted. Secondly the characters distinguishing Lampra from Cory-
morpha are not sufficient to justify a separation of genera.

A closer examination of the numerous northern species of Lampra described will show their un-
maintainability. A survey of the figures forming distinguishing characters is obtained by grouping the
criteria stated as follows:

Nomenclature

Height of
Hydro-
caulus

Blastostyles

Tentacles
Proximal Distal

Gonophores

Number

Length

Number

Lengtli

Arrangement

Length

Monocauhcs groenlandica Allman 1876.

1 inch

7-8

?

ca. 20

"Modera-
tely long"

"numerous"

short

no tentacles

Lampra arctica Jaderholm 1909

45 mm
60 mm

22

5— S mm

25

25 mm

5-6 close circles

?

globular,broadlyoval
with rounded apex

Corymorpha spitzbergensis Broch 1909. .

12

5 mm

25

20 mm

4-5 close circles

2 mm

oviform or globular
without tentacles

Lampra atlantica Bonnevie 1899 ....

So mm

10

4—6 mm

10

10-20 mm

several close-
set circle

?

without tentacles

100 mm

10

30-40 mm

30

30-40 mm

two circles

?

without tentacles

Lampra socia S w e n a 11 d e r 1 903

45 nm

18-32

till 25 mm

29-37

35 mm

numerous
close-set circles

up to
q mm

9 more rounded,

cf sub-oval,
without tentacles

The original discription given by Allman (1876) is founded on a series of young individuals
from Godthaab, in which it may be observed how the number of proximal tentacles increases by new
tentacles being established and growing out among the old ones. How far the number of tentacles
may increase in this way, cannot be settled. But no definite rule of the increase being trace-
able, we here face one of the reasons of the great varying of the numbers of tentacles. In these young
individuals it is also interesting to observe that the distal tentacles are established quite irregularly
Tab. II Fig. 14), and that the blastostyles arise as simple fingerformed bulges of the polyp wall. The
gonophores only appear at a rather late stage of development.

The skeletonlike figures and rather deficient diagnosis of the species given by Allman long
impeded its recognition, and, therefore, only a couple of specimens occurring in the museum of Copen-
hagen have later on been correctly referred to his species Monocaulus groenlandica. Bonnevie (1899)
accordingly describes two new, closely related species, Lampra atlantica and L^ampra purpurea. The
former species is distinguished from the latter mainly by its small number of tentacles, having only
ten proximal ones. However, even though this difference must be regarded as very large, as far as in
the single specimen of Lampra purpurea as many as thirty proximal tentacles have been observed,
we cannot acknowledge it as a sufficient specifical distinguishing character after the examination of a
larger material of the species. The rather numerous specimens found in the Trondhjem fjord present

5*

36

HYDROIDA

so great a range of variability that the number stated in Laiiipra atlantica must only be considered
as an extreme variation. The variation of the individuals found in the Troudhjem fjord is even larger
than stated by Swenander (1903); individuals have been found with only 15 tentacles in the proximal
whorl. The difference in the shape of the gonophores, being either subglobular or oval with attempts
at tapering, is of little importance. Swenander points out that the female gonophores are more
globose, the male more oval. In a specimen picked up north east of the Seydisfjord (Iceland) the gono-
phores are partly globular, partly oval, with the same attempt at tapering towards the distal end as
is shown in the figure of Bounevie (1899, Tab. Ill, Fig. 1 a). However, one criterion is still left,
the distal tentacles of La?npra purpurea being arranged in two separate circles, while in other spe-
cies they are placed in several irregular and close-set circles. From the comments of Bonnevieit
appears that the description has mainly been based on the drawings of G. O. Sars, which were exe-
cuted on board ship. In these drawings the double whorl is not peculiarly clearly rendered ; nor can,
from the remnants of the original specimen kept, the character be ascertained any longer. From the
table set up of the specimens from the Danish collections, however, it appears that, from individuals
with a distal whorl consisting of two rows to individuals with a distal tentacle whorl of several rows,
every transition may be pointed out. Thus neither this table nor the criteria stated in the other table
may be turned to account for the purpose of attaching any peculiar systematical importance to this
character. Lampra atlantica and Lampra purpurea, therefore, cannot be recognized as two separate
species, and are moreover identical with Corymorpha groenlandica.

For a thorough examination of the species we are indebted to .Swenander (1903), who considered
the Lampra of the Trondhjem fjord as a peculiar species, Lampra socia. From what I have stated
above, the shape of the gonophores, applied by Swenander as a main character distinguishing the
species from Lampra purpurea Bonnevie, cannot be maintained as a criterion. The number of the
blastostyles then remains; Bonnevie, for both the species mentioned, states 10 blastostyles; Swen-
ander, for Lampra socia, 18 — 32. Still Swenander has not found the minimum for the individuals
of the Trondhjem fjord; as a matter of fact, specimens with only 15 blastostyles are now in hand.
In the Danish material collected from the northern Atlantic the number is throughout lower, varying
from 10 to 28, thus bridging the difference between Lampra socia and the species stated by Bonne-
vie. Also the other distinguishing characters, the emphatic demarkation of the hydrocaulus from the
polyp, or its gradual transition into the latter, and the colour of the animals, are varying from one
individual to the other, forming no strongly defined limits. The demarkation of the stem from the
polyp more or less emphatic, is, in living individuals, varying according to the state of contraction, as
in other species of Corymorpha. Therefore, also Lampra socia must be considered as a synonym of
Corymorpha groenlandica.

Jaderholm (1909) and Broch (1909) describe two new species, respectively Lampra arctica
and Corymorpha spitzbergensis. The table at once shows that they come within the range of variation
of Corymorpha groenlandica. As to Lampra arctica the short and thick blastostyles, maintained by
Jaderholm (1909) as a good criterion, are in fact to be looked upon as a mere phenomenon of con-
traction which may be partly observed even in preserved material, where in the same individual some
blastostyles may be short and thick, while others are thin and strongly extended. Illustrative in this

HYDROIDA

37

respect is the individual nr. 10 of the first table, the length of the blastostyles varying from 5 to 18
mm., and the thickness being inversely proportional to the length. The rest of the distinguishing
characters fall under what has been earlier stated.

Corymorpha groenlandica is a typical form characteristic of the great deep of the cold area. It
proves to be widely distributed, from Spitzbergen to the Faroe Islands, and from Norway to Green-
land. It has also been recorded from Davis Strait. In the seas far to the north it rises to more shallow
waters. Thus it has been recorded near Spitzbergen at the depth of only 45 metres (Broch 1909).
A remarkable geographical exception is formed by the occurrence of the species in the deeper Atlantic

20om. 6 oo n. ._ 1000 m. i 2000m.

Text-fig. I. Localities of Corymorpha groenlandica in the Northern Atlantic.

strata of the Trondhjem fjord. At present the occurrence of the species in this locality cannot be
accounted for. But a great deal may be said in favour of the notion that we have here in hand a
relict form, which has been able to accommodate itself to the altered circumstances in the same way
as Tubularia regalis Boeck and Stegopoma plicatile (M. Sars) which are rather frequently occurring
on or at the Lophohelia reefs of the fjord.

Corymorpha sp. indet.
Indeterminable remnants of species of Corymorpha occur from the following localities:
"Ingolf" St. 28, 65°i4' N., 55°42' W., depth 420 fath., + 3°5 C, attached to the tube of a Pectinaria.
_ -124, 67°4o' - i5°4o' - - 495 - -ho°6-

38

HYDR01DA

Section Filifera Kiihn.
Family Clavidae.

Hydroids forming colonies, with polyps fusiform or capitate, the distal part of which is coni-
cally tapering. The stinging cells are small and rodformed. The tentacles are filiform, irregularly dis-
tributed over the body of the polyp, now and then showing a heterogeneous development or even
reduced to a single large tentacle. The endoderm forms a homogeneous gastral cell-layer through
the whole of the polyp. The colonies have no calcareous skeleton.

The family Clavidae, as it is here defined, includes the genus much in dispute Monobrachium,
which has been distinguished by most investigators as the representative of a family of its own, Mo-
nobrachiidae. This family is maintained even by Kiihn (1913), who has obviously failed to notice
the significant pointing out by Vanhoffen (1909) of the heterogeneous development of the tentacles
of Campaniclava clionis Vanhoffen, forming an obvious link between Monobrachhim and the other Cla-
vidae. Vanhoffen, therefore, does away with the family Monobrachiidae and refers Monobrachhim
to Clavidae. In this he is rightly followed by Stechow (1913).

Gen. Clava Gmelin.

The reptant colonies have polyps capitate or subfusiform with filiform tentacles irregularly
distributed over the polyp. The proboscis is conically pointed. The hydrocauli are not surrounded
by any distinct stiff perisarc. The gonophores are clustered on the polyp below the portion bearing
tentacles, or seated on the reptant stolons either solitary or in clusters.

According to this diagnosis also the genus Rhizogeton must be included under Clava. The two
genera have hitherto generally been distinguished on the ground that in Rhizogeton the gonophores
are seated 011 the stolons, while in Clava they are borne by the polyp itself. This criterion, however,
is too insignificant to justify a division of genera, and it is also suggested by Stechow (1913) that
very likely the two genera have to be united. In his key of genera, indeed, Stechow puts down
Rhizogeton in a parenthesis under Clava.

Clava multicomis (Forskal) Gmelin.

1775 Hydra multicomis, Forskal, Descriptioiies animalium, p. 131.

1776 — squamata, Miiller, Zoologia Danicce Prodromus, p. 230.

1788 Clava parasitica, Gmelin, in L,inne: Systema natura Ed. 13, vol. I, p. 3131.

On the reptant stolons the capitate or almost fusiform polyps are placed in close or opener
clusters. The stem of the polyp is without perisarc. The filiform tentacles are irregularly distributed
over the distal parts of the polyp.

The gonophores are cryptomedusoid, and placed in larger or smaller groups like clusters of
grapes closely below the portion of the polyp bearing the tentacles.

IIVDROIDA

39

The species may be divided into two forms:

Forma genuina, growing, in colonies more openly constructed, on stones and shells (My til its);
it is delicately built and bluish or rose-coloured.

Forma squamata forming clusters of polyps more brick-coloured or yellowish-red on the leaves
of Fucoideae \ its polyps are large and robustly built.

Material :

Iceland : Reykjavik

Vestmauney
The Faroe Islands: Sundelaget

north of Kvalvik

depth 3 — 4 fathoms,
on the shore (on Fucoideae)

on the shore (on Fucoideae)

(There also occur specimens marked "Faero" without particular data).

Clava multicornis and Clava squamata are recorded by most investigators of hydroids as two
separate species; the distinguishing characters, however, are rather vague, being made out by the
closer or opener occurrence of the polyps in the colony or by the colour of the colonies. A copious
material from various localities, in fact, presents all transitions possible, and it is virtually impossible
to draw any certain limit between the species. A closer inquiry soon makes clear to us that the
points of difference must be of biological nature, and the two species, therefore, have to be regarded
only as biologically determined "forms" of a single species, which I, accordingly, denominate forma
genuina and forma squmata. The occurrence of typical colonies of the forma genuina, which are, in

Text-fig. K. The distribution of Clava multicornis in the Northern Atlantic.
(In the hatched part of the Norwegian coastal region the occurrence is rather scarce).

4o

HVDROIDA

fact, rather rare and scattered, is bound to substrata of stones, which may be, at a pinch, replaced by
the shell of a Mytilus, while the colonies luxuriantly developed of the forma squamata are resident on
the leaves of the Fucoidcae, where certainly the supply of food is much more copious.

The description of Forskal (1775) being older than that of O. F. Miiller (1876), we have
according to the rules of nomenclature in force, to drop the specific name employed by the latter,
Clava squamata and to maintain the denomination bestowed on the species by Forskal, Clava multi-
cornis. Its limitation from the American species Clava leptostyla h- Agassiz, has not as yet been
ascertained, and it seems on the whole questionable if the two species are really to be distinguished.

Clava multicornis is a boreal species, which seems, nevertheless, to be able to penetrate far
into the Mediterranean (Babic 1904). It is a littoral form, and forma squamata has been found only
in the tidal zone; forma g enu/na, on the other hand, at rare intervals, has been met with a little ben-
eath the tidal zone in places with rather small salinity. Fabricius (1780) records the occurrence
of the species at Greenland without particular statement of locality; however, it has not afterwards
been observed in this place. On the other hand, the species seems to occur not uufrequently on the
south west coast of Iceland. It is frequently met with at the Faroe Islands, and is found everywhere
round the British Isles and on all coasts round the North Sea. Its occurrence at the northern parts
of the coast of Norway is not sufficiently accounted for, but does not seem to be particularly frequent.

Gen. Merona Norman n.

From the reptant stolons arise unbranched, chitinous polyp stems. In the upper part of the
stem the perisarc is so wide that the polyp can be retracted into it, though developemeut of a hydro-
theca is not indicated. The filiform tentacles are irregularly spread over the polyp. The gonophores
are borne upon reduced polyps (blastostyles) arising from the reptant stolons.

With great hesitation I set up Merona as a genus of its own. It is distinguished from Cory-
dendrium van Beneden (1844) only in mere trifles of no great importance. Thus its polyp stems
are unbranched, while the hydrocaulus of Corydendrium is richly branched. Another distinguishing
character may perhaps be sought in the quality presented by Merona in its wide perisarc, into which
the polyps are retractile. But none of these criteria can be said to be of properly generic value. When,
nevertheless, Merona is provisionally maintained, it is due to the fact that only an exceedingly scarce
material of a single species is in hand, and that the state of preservation of this material allows of
no closer inquiry into the polyps.

Merona cornucopiae Norman.

1864 Tnbiclava cornucopiae, Norman, On undescribed British Hydrozoa, Actinozoa and Polyzoa, p. 357.

1865 Merona Norman, On Merona, an undescribed genus of British Hydrozoa, p. 262.

The hydrocauli are unbranched and attain a height of about 5 mm.; the stems are narrowest
at the base and increase gradually in diameter till they attain their greatest width closely below the

HVDROIDA

41

extended polyp; they are without rings; at most there is some faint and irregular wrinkling here
and there. The polyp is fusiform with the tentacles irregularly distributed all over the surface; the
polyp may be retracted into the broader distal portion of the hydrocaulus.

The structure of the gonophores seems to be strongly reduced. They are developed at the
upper part of blastostyles without tentacles, at most 1 mm. high.

Material:

The Faroe Islands: 13 miles West to South of Munken, depth 150 fath. (on Cardium sp.).
— 9 — East South East of Bispen, — 70 — ( - - ).

20om. - — 600m. ._ ....(Doom. 2000m.

Text-fig. L. Localities of Merona corimcopiae • and Monobrachium parasitum A in the Northern Atlantic.

Merona corimcopiae was first described as a Tubiclava by Norman (1864). But as the latter
genus is characterized by the gonophores being borne on the polyps, he thought he had better set
up a new genus Merona (1865) for the species in hand, bearing its gonophores on polyps strongly
reduced or on blastostyles. This criterion, however, is of subordinate importance and would by no
means justify the separation of two genera. However, from the drawings occurring in literature, a
much essential point of difference urges itself. The perisarc of the species of Tubiclava is not so wide
that the polyp can be retracted into it, while this is the case with Merona. The division, therefore,
seems well founded. But at any rate a renewed examination of the two genera is needed.

Merona eornucopiae seems only to occur attached to shells of living mollusks, and has been
found on species of the genera Cardium, Astarte, and Dentaliitni. The species does not seem to be
very frequent; it has previously been recorded from the sea to the north of the Shetlauds at the
depth of 80—100 fathoms, and from the coast of Northumberland. To these localities are now to be

The Ingolf-Exrcdition. V. 6. 6

42

HVDROIDA

added the seas to the south of the Faroe Islands at the depth of 70 — 150 fathoms. All the finds are
thus situated in the boreal area, on the border of the warmer Atlantic regions (Text-fig. L).

Gen. Monobrachium Mereschkowsky.

Reptant colonies, whose cyliudric polyps are provided with a solitary large tentacle. Besides
the nourishing individuals bearing tentacles, also machozooids with no mouth and no tentacles occur.
The polyps have no distinct stem and are not covered with perisarc. The gouophores are eumedusoid
and attached to the stolons.

The very peculiar Arctic genus of hydroids first described by Mereschkowsky (1877) has been
more closely investigated by Wagner (1890) and Bonnevie (1899). In the only species known of this
genus the eumedusoid gouophores have a rudimentary spadix, and the germ cells are accordingly
developed along the radials canals. On this ground Bonnevie maintains that the species is closely
related to the Lcptonicdusae, and that the genus has to be placed proximately between athecate and
thecaphore hydroids. Kuhn (1913), on the other hand, holds that the organisation of the gouophore
cannot be considered as any certain proof justifying such a supposition, and points out that the trans-
ition of the gouophore from independent free existence into sessile mode of life can effect a secondary
displacement of the gonads in many different ways without any necessity that this should be indica-
tive of nearer or remoter relationship. Apart from this, however, there is an additional reason against
the supposition of Bonnevie. As is pointed out by Vanhoffen (1909), we have in hand a medusa-
form obviously nearly related, Catablema, which, when somewhat damaged, is very easily mistaken
for a Leptomcdusa, but which is, in fact, a genuine Tiaride. Vanhoffen even presumes that Cata-
blcma really is the medusoid generation of Monobrachium. But in that case it remains to show that
the gouophores of Monobracliinm are not sessile as they have hitherto generally been supposed to be.

The explanations of Vanhoffen (1909) and Kiih 11(1913) make good that Monobrachium takes
no intermediate place between athecate and thecaphore hydroids. But the place of the genus among
the athecate hydroids would still be equally uncertain if the peculiar species Campaniclava c lion is
Vanhoffen (1909) had not shown us, by its heterogeneous development of the tentacles, the unquesti-
onable link between Monobrachium and the normal-looking forms of Clava. Therefore there is no
reason any longer to regard the genus as the representative of a peculiar family; as pointed out by
Vanhoffen, it ought to be classed with the Clavidae.

Monobrachium parasitum Mereschkowsky.
1877 Monobrachium parasitum, Mereschkowsky, On a new Genus of Hydroids, p. 225, pi. 5 fig. 1 — 6

pi. 6 fig. 7—14.
1899 parasiticum Bonnevie, Norske Nordhavs Expedition, p. 51.

Reptant colonies, whose polyps are dimorphically developed; beside cyliudric polyps with ori-
fice and a vigorous tentacle, also machozooids without mouth or tentacles occur. The nourishing

HYDROIDA

43

polyps are provided with a ring of stinging cells above the base of the tentacle. The stolons form a
network of anastomosing tubes.

The gonophores are eumednsoid with a rudimentary spadix and with the generative cells
placed along the four radial canals. The colonies are bisexual.
Material:

Greenland: Egedesminde (on Tcllina calcarea).

The Kara Sea ("Dijmphua").

Monobrachiitm parasitum is indigenous to the middle parts of the litoral region far to the north.
It is recorded from Spitzbergen, the Kara Sea, the White Sea, and the west coast of Greenland
(Text-fig. L).

Family Bougainvilliidae.

Hydroids forming colonies with polyps fusiform or capitate, whose oral portion is conically
pointed. The stinging cells are small and rodshaped. The tentacles, which are filiform, are placed in
a main whorl round the polyp; the stinging cells are equally distributed all over the surface of the
polyps or in less distinct transverse belts round them. The polyps are quite naked or surrounded by
a jellied, lithe, and pliable pseudohydrotheca below the tentacle whorl. The eudoderm is differentiated
into an oral portion, consisting of indifferent small-nucleated cells between which occur a large number
of mucous gland cells, and the proper gastral portion; the limit is formed by the tentacle whorl. The
colonies have no calcareous skeleton.

The diagnosis states for the family the same range as was practically already given by Bon-
nevie (1899), whom the later authors have generally followed. Kiihn (1913) divides the family into
three subfamilies, two of which, Hydractinii)iac and Atractylinae, are represented in our northern seas.
The main distinguishing mark stated by Kiihn is that Hydractiniinae are stated to have a vigorous,
crustformed skeleton, while Atractylinae, on the other hand, have hydrocauli covered with periderm.
However, this character does not seem to be of the importance Kiihn attached to it. In young
colonies the stolons have not coalesced into a crust, and the development of the skeleton is not parti-
cularly vigorous. There is even every probability that several species of Stylactis do not at all assume
such crustformed skeleton-formations, even when advanced in life. On the other hand, we also know
species of Hydractiniinae, in which the hydrocaulus covered with periderm has been reduced to a mere
minimum. The character, therefore, must be characterized as a merely gradual one, and can hardly be
turned to account as fundamentum divisionis for higher groups.

A very different interest is attached to the peculiar occurrence of pseudohydrotheeae met with
in the Bougainvilliidae. I set aside the socalled pseudohydrotheeae of Clathrozoon (the subfamily Hy-
droceratininae, stated by Kiihn 1913); in fact, this group is not yet so well known that we are able
to judge of it entirely, and its "pseudohydrotheeae" do not seem to form such a parallel with the for-
mations of the thecaphores as those found in certain other Bougainvilliidae, namely in Pcrigo-
nimus. In this species the ectoderm of the polyp has secerned a jellied pseudohydrotheca, which has
coalesced with the polyp along its distal margin, and to which the basal portion of the supporting

44

HYDROIDA

lamella of the polyp is attached by small ehitinous bodies similar to those found in several theeaphores.
This pseudohydrotheca is but little visible, or, with intact polyps, when they are extended, almost
untraceable, while in contracted polyps it lies round the basal portion of the polyp like a cup richly
folded. It might be obvious to regard it as the precursor of the real hydrotheca. Perhaps it might
be regarded as a character sufficiently important for the purpose of distinguishing a subfamily: How-
ever, the matter has, as yet, been too little examined as to allow the forming of a reasonable opinion;
we have, provisionally, to regard it as a generic character.

Gen. Hydractinia van Bene den.

The stolons of the reptant colonies, when young, will generally form an open meshwork which
afterwards most frequently changes into a continuous ehitinous crust. The crust is commonly carrying
spines of various appearance, or may grow out into branched formations of colonies. The polyps are
cylindrical or capitate with conically pointed oral portion. The tentacles are placed in a whorl below
the mouth. There is no erect hydrocaulus covered with perisarc. The polyps are heterogeneously devel-
oped into larger nourishing individuals bearing tentacles and into spiralzooids bearing no tentacles; the
latter occur at the extremities of the colonies. — The gouophores are supported by polyps more or
less transformed (blastostyles) or arise directly from the stolons.

According to this diagnosis, also Podocorync, Oorhiza and Stylactis, earlier set up as genera
are included under Hydractinia, The only reason of distinguishing between Hydractinia and Podo-
corync has been sought in the power of the last-mentioned genus of producing free-swimming medusae.
However, Bonnevie (1899) has described a couple of species, Hydractinia Allmani and Hydractinia
omata, having medusoid gonophores less strongly reduced with radial canals, and from Africa has
been recorded a species, Hydractinia Michaelseni Broch (1914), whose male gonophores are perfect
medusae, which, however, do not seem to break away normally. Also Ktihn (1913) seems to incline
to the opinion that the separation of the two genera is questionable. The intermediate forms of gono-
phores mentioned, in fact, forbid the drawing of a certain limit between the genera, and, therefore, the
proper thing to be done, is, indeed, to draw in Podocoryne under Hydractinia.

The genus OorJiiza is based on the fact that the gonophores are seated, not, as in Hydrac-
tinia, on blastostyles, but, on the contrary, on a short stem rising directly from the stolons. A review
of our northern species of Hydractinia, however, shows that, in fact, this criterion is of no vital im-
portance. In Hydractinia humilis Bonnevie and Hydractinia S'arsii Steenstrup the gonophores
are borne on polyps fully developed of the same size as the sterile nourishing individuals; in Hy-
dractinia camea M. Sars the polyps bearing gonophores are, certainly, fully developed individuals,
provided with tentacles; but they have a smaller number of tentacles, and are smaller than the sterile
nourishing polyps. In Hydractinia Allmani Bonnevie, Hydractinia omata Bonnevie, and Hydrac-
tinia echinata (Fleming) the reduction is carried still further, the tentacles being reduced or wholly
disappearing, so that the bearers of the gonophores are here typical blastostyles. In Hydractinia carica
Bergh, finally, the polyp has been reduced to a stem, round the apex of which the gonophores are

HYDROIDA

45

placed in a whorl. In fact, between this condition of things and a solitary gonophore seated termin-
ally on a polyp wholly reduced to a stalk, there is no great gap, and at any rate the criterion is not
essential enough to be turned to account as fundamentum divisionis. Also Oorliiza has, accordingly,
to be included as a synonym under Hydr actinia.

Stylactis is yet left to be mentioned, being distinguished by the stolons forming an open mesh-
work and no continuous chitinous crust. In his excellent elucidation of Hydractinia and Podocoryn, ,
Hi neks (186S) calls attention to the fact that, in the species then known, the stolons at first form
an open mesh-work and do not till later on coalesce into a continuous crust. Young colonies of Hydractinia
camca, which are in our Norwegian seas very commonly observed on living specimens of Nassa reticu-
lata, in most cases show this open mesh-work of stolons and, therefore, easily run the risk of being
undiscerniugly characterized as Stylactis. In the African species, Hydractinia Michaelseni Broch
and Hydractinia fallax Broch, large colonies show a mixture of characters of Stylactis and of Hy-
dractinia, and, accordingly, there is no reason to maintain the two groups as distinct genera. They
communicate with each other by intermediate forms. It is probable that several species of Stylactis
have been based on young colonies of typical species of Hydractinia. This probability, indeed, cannot
be contested even by the occurrence of gonophores, because, in young colonies of Hydractinia carina,
where the stolons have not yet coalesced into a crust, gonophores are frequently observed. A species
as Stylactis arctica J ad er holm (1902) has obviously to be judged summarily as such a young Hy-
dractinia. Also Stylactis, therefore, has to be included among the synonyms of Hydractinia.

Hydractinia Sarsii (Steenstrup) Bonnevie.

1846 Podocoryua camca, M. Sars, Fauna littoralis Norvegiae, Heft 1, p. 7.

1850 Podocorync Sarsii, Steenstrup, in: Liitkeu, Nogle Bemrerkninger om Medusernes systematiske

Inddeling, p. 33.

1872 Stylactis — Allman, Monograph of the Gymnoblastic or Tubularian Hydroids, p. 303.

1892 Podocorync camca, Leviusen, Medu'ser, Ctenophorer og Hydroider fra Gronlands Vestkyst, p. n.
1899 — — pars, Sremuudsson, Bidrag til Kundskabeu om de islandske Hydroider, p. 50.

1899 Hydractinia sarsii, Bonnevie, Norske Nordhavs Expedition, p. 45.

The reptant stolons are covered by a continuous chitinous coenosarc, whose surface is studded
with small spines, among which are found, often by groups, large, vigorous thorns, up to 0.5 mm. high,
of irregular conical shape with closed apex abruptly cut off. The polyps attain a length of 2.5 mm.
and have 10 or 20 tentacles in a dense, proximately double, whorl, below the oral portion. Spiral-
zooids have not yet been pointed out.

The gonophores are cryptomedusoid and placed, to the number of three or six, round fully
developed polyps of the same size as the sterile nourishing individuals.

Material :

Greenland, the harbour of Godthaab
Iceland, Seydisfjord

depth 12 fath. (on Hyas a ran cits).

(on Carcinus maenas).

46

HYDROIDA

The well developed colony in hand has been wrongly determined as Podocoryne carnea. It is
hardlv intelligible that Bedot, in his "Materiaux pour servir a Phistoire des Hydroides", should have
followed A 11 man (1872) and referred this species to Stylactis; it is one of the few species of Hy-
dractinia which, even at the extremities of small colonies, show no indication of the open network of
stolons for which Stylactis should be distinguished.

The species seems to be a boreal one, but it has hitherto been recorded only from very few
localities, as it has probably been mistaken for Hydractinia carnea also by investigators subsequent to
M. Sars (1846). It has previously been recorded only from the coast of Norway near Bergen. In the
Danish collections is found a well developed, though sterile, colony from Iceland (Seydisfjord),
seated on the claw of a strand-crab. It seems to be the same species which is recorded, by the name

200 m. __._ 600m.

Text-fig. M. Finds of Hydractinia Sarsi

.— _._ 1000 m.

end Hydractinia carica *

2000m.

in the Northern Atlantic.

of Podocoryne carnea, from the north of Iceland, on the operculum of a Balanus Hammeri (Ssemunds-
son 1902, 191 1); here is only found the chitinous crust; but it differs considerably from the crust found
in Hydractinia carnea, and, on the contrary, wholly agrees with Hydractinia Sarsii (Tab. I Fig. 12).
Finally also West Greenland (Godthaab) has to be added to the localities where the species has
been found (Text-fig. M).

Hydractinia echinata (Fleming) van Beneden.
1828 Alcyoninin ecliinalian, Fleming, A History of British Animals, p. 517.
1841 Hydractinie, van Beneden, Recherches sur la structure de l'oeuf dans un nouveau

Polype (genre Hydractinie), p. 89.
1909 Hydractinia monocarpa pars, Broch, Die Hydroideu der arktischen Meere, p. 199.

srenre de

HYDROIDA

47

The reptant stolons are covered by a continuous chitinous coenosarc, whose surface is studded
with small prickles, among which occur larger chitinous spines about 1.5 mm. high, provided with lon-
gitudinal rows of more or less regular small teeth. The large spines now and then show a tendency
to divide at the apex. The polyps are up to 4 mm. long, whitish or faintly reddish, with 20—30
tentacles in a dense whorl below the oral portion. The tentacles form a belt which appears double
because of alternating displacement. Spiralzooids without tentacles occur along the margin of
the colony.

The gonophores are cryptomedusoid, placed, to a number of 3 or 6, round reduced polyps with
rudimentary tentacles.

Material :

Greenland: Upernivik, depth 80 — 90 fathoms without particular data, from a cod's stomach.
Skagerrak: the channel near Vinga (Bohuslan), depth 50 fath.

Hydractinia echinata in its large chitinous skeleton-spines (Tab. I Fig. 9 and 10) has a very
typical armour impeding a confusion with other northern species. It is an Atlantic-boreal species,
showing a great power of enduring both high and low temperatures. It occurs very frequently in
the North Sea, along the coasts of Great Britain and Ireland, goes to the south as far as into the
Mediterranean, and is also found on the east coast of North America. The species belongs to the
litoral region and almost always goes together with Eupagums Bernhardus, on whose house it settles.
When we consider the distribution of the species along both sides of the northern Atlantic, we must wonder
that it has not yet been observed at the Faroe Islands, and that only a single specimen has been met

._ 1000 m.

Text-fig. N. The occurrence of Hydractinia echinata in the Northern Atlantic.
(The hatched parties denote according to litterature a scattered allthough common occurence).

48

HYDROIDA

with at Iceland. This specimen which was found on the north side of the island, was originally
recorded by Whither (1880), and has afterwards been revised by Saemuudsson (1902). It is a pecu-
liarity of the specimen that it is seated on the operculum of a Balanus Hdmmeri, and not on the
house of the Bernhardus crab. The species has been recorded once in the Arctic water-layers near Jan
Mayen (v. Lorenz 1886). In a previous work (1909) I gave utterance to the supposition that the
variety recorded by Levinsen (1892) had probably to be referred to the high-arctic species Hydrac-
tinia monocarpa Allman. An examination of the specimens mentioned, however, shows that this suppo-
sition is wrong. The specimens are unquestionable Hydractinia echinata with skeleton strongly deve-
loped. One of the specimens is distinguished by being attached to the shell of a living Buccinum
hydrophanum. The species, thus, proves able to occur now and then under wholly high-arctic conditions.

Hydractinia carica Bergh.
1887 Hydractinia carica, Bergh, Goplepolyper fra Karahavet, p. 3, Taf. 28, Fig. 1.
1899 minuta, Bonuevie, Norske Nordhavs-Expedition, p. 48, Tab. I, Fig. 3.

The reptant stolons are covered by a chitinous layer of coeuosarc, without small prides, but
bearing here and there vigorous spines, singly placed and up to 0.5 mm. high, conical with rounded
apex. The polyps attain a length of 2 mm., and have 10 — 14 rather vigorous tentacles jilaced in a
single whorl below the oral portion. Spiralzooids are not traceable.

The gouophores are cryptomedusoid, placed, to a number of 3 — 6, round polyps almost wholly
atrophied, forming, if anything, only a short stalk, or showing rudiments of tentacles slightly indicated.

Material :

The Kara Sea: Petuchoffskoi Schar depth 7 fath. (the original specimen described by Bergh 1887).

An examination of the original specimen, determined by Bergh, shows with full certainty

that it is the same species that has afterwards been described by Bonne vie (1899) by the name of

Hydractinia mimtta. The diagnoses, however, when compared, will show some points of difference.

Bo nne vie does not mention the skeleton-formations at all while on the other hand, the statements

of Bergh convey the impression of a greater resemblance to Hydractinia echinata than it really bears.

Hydractinia carica lacks the small prickles found in the species last mentioned, and more vigorous spines
j— ^ •*/ ^V

also occur rather scarcely; the latter (Tab. I, Fig. 11) are smooth and more conically tapering than those
i as

of Hydractinia Sarsi. The main difference, however, between the diagnosis of Bonuevie and that

of Bergh is implied in the mention of the blastostyles. Bergh states in his diagnosis "Sporosacs
borne on very short, rudimentary hydrants, without or with very few (1—4) tentacles", while in the
diagnosis of Bonuevie we find "Fixed gonophores without radial canals, from 3 to 5 in circle round
the inconspicuous blastostyles", and in her short comment Bonne vie further states that the species
is distinguished for "the complete atrophy of the gonophore-bearing hydranths". The specimens deter-
mined by Bergh show a great varying as to the development of the fertile polyp; it may, as he tells
us, have 1 — 4 tentacles; but they are a great deal more reduced than is apparent from his pictures,
and agree better with the drawings published by Jaderholm (1909, PL 2, Fig. 10 — n). However,

HYDROIDA

49

there are in the colonies also numerous blastostyles, which are wholly devoid of rudiments of tentacles,
and accordingly only forming a stalk in the same way as is indicated by the diagnosis of Bonuevie.
But there always occurs a small polyp, and a "complete atrophy" of the polyp is in no case demon-
strable; nor is it obvious from the imperfect figure of Bonnevie (1899, Tab. I, Fig. 3). — The great
variation of the blastostyles of the original specimens determined by Bergh, shows us that the
species stated by Bonnevie may be founded on a colony where the blastostyles carrying tentacles
were reduced to a minimum in number. But this does not give sufficient reason for maintaining it
as a peculiar species beside Hydractinia carica.

Hydractinia carica is an Arctic litoral species, which, in boreal waters, proves able to penetrate
along the West coast of Norway as far as Bergen (Text-fig. M). It has been found elsewhere only
in high arctic regions, in the Kara Sea, in the Murman Sea, and at Spitzbergen. It has also been re-
corded by Jaderholm (1909) from Davis Strait.

Gen. Bougainvillia Lesson.

Upright colonies with branched hydrocauli clothed with a perisarc. The polyps are fusi-
form with the tentacles placed in a whorl below the conically pointed oral portion. The polyps are
naked without the slightest attempt at formation of pseudohydrotheca round their proximal portion.
The gouophores are placed on the stems of polyps fully developed or reduced (blastostyles). In the
latter case, the unbranched polyp stem will sometimes rise from the hydrorhiza instead of from the
hydroeaulus.

A closer inquiry into the distinguishing characters and their systematic value, shows us that there
is no reason to distribute the species of Bougainvillia on the three genera Bougainvillia, Dicorync, and Hetero-
cordyle. Sufficient cause for distinguishing between Bougainvillia and the two other genera is not at all
given by the fact that the former has medusoid gonophores, while the two other genera have styloid go-
uophores. In mentioning the genera earlier treated, I have sufficiently explained the insignificance of this
criterion as to classification. Then remains the other distinguishing mark that the gouophores of Bougain-
villia develop on the stems of some fullgrown polyps, while in Dicorync and Hcterocordylc they are devel-
oped on the stems of reduced polyps (blastostyles). The genus Hydractinia shows us a full parallel to this
condition of things. But because of the many and close connecting links between one extreme and
the other, it has been agreed that the stronger and weaker specializing into nourishing polyps and
blastostyles cannot be employed as a generic character. When, on the other hand, this has been done
with Bougainvillia and Dicorync and Heterocordyle, the only reason must be that, between the few
species known of these genera, most of the links occurring in Hydractinia are wanting. This lack,
in fact, is not a sufficient reason to elevate, in one case, the character to an importance which is denied
in another case, even within the same family. It is not right to base the genera Bougainvillia, Di-
corync and Hcterocordylc on characters that must be used with discretion as specific characters
in Hydractinia. Further, as to the distinguishing mark between Dicorync and Hcterocordylc, it is
still more diminutive. Hcterocordylc conybcari Allman, the only species known of the genus, is so like

The Ingolf-Expedilion. V. 6. 7

5°

HYDROIDA

Dicoryne conferta (Alder) as to confusion, and the two species have probably more than once been mis-
taken for one another. Both the species have styloid gonophores; but in Hcterocordyle they are ses-
sile, while in Dicoryne, when ripening, they assume cilia all over, develop two tentacles, and break
away. This is, unquestionably, a phenomenon of mere biological adaptation and cannot be recognized
as sufficient for distinction of genera as long as it is not accompanied by a thorough change of the
organization of the sterile parts of the colony. It is evident that Dicoryne and Hcterocordyle must be
drawn together into one genus, and moreover that this genus must be united with Bougainvillia.

. boom.

Text-fig. O. The habitat of Bougainvillia conferta in the Northern Atlantic.
(In the hatched regions the litterature denotes the occurence of the species without strict localities).

Bougainvillia conferta (Alder).
1856 Eudcndrhon conjertum, Alder, A Notice of Some New Genera and Species of British Hydroid

Zoophytes, p. 354, pi. 12, fig. 5-8.

The colonies attain a height of up to 15 mm., and exhibit a rigid appearance. They have a
distinct main stem with short side-branches. The perisarc is vigorously developed and dark brown-
coloured. The small fusiform polyp attains a length of about 0.5 mm.; it wears about 16 tentacles in
a single whorl below the oral conically pointed portion.

The gonophores are styloid and break away. When ripening, they assume a peculiar oviform
shape, develop two filiform tentacles, and put on a complete suit of cilia all over. The gonophores
are seated, gathered in a belt, somewhat below the apex of blastostyles, which arise from the hydro-
caulus or, in smaller numbers, from the hydrorhiza. The blastostyles show no indication of tentacles.

HYDROIDA 51

Material:

Iceland: Talkuafjord (without particular data).

Reydarfjord, depth 163 metres.
The Faroe Islands (without particular data).

Bougainvillia conferta is a southern-boreal species penetrating as far as into the Mediterranean ;
towards the north it goes, along the coast of Norway, only as far as Lofoten. It has been recorded several
times from Iceland, in the warmer water-layers along the west- and south-coasts of the island, but it
has not yet been pointed out at Greenland. As a new locality must be added the Faroe Islands. The
species is indigenous to the litoral region.

Gen. Perigonimus M. Sars.

The hydranth stems rise immediately from the reptaut stolons, or there are formed upright
rhizoeaulomes bearing the polyps. The polyp stems are sometimes divided into a couple of branches;
still hydrocaulus, properly speaking, cannot be recorded. The polyps are fusiform, with the tentacles
placed in a whorl below the conically pointed oral portion; below the tentacle whorl they are sur-
rounded by delicate pseudohydrothecae, superiorly connected with the ectoderm of the hydranth, and
inferiorly passing into the chitinous perisarc of the stem. The stinging cells show attempts at being
arranged in transverse belts on the tentacles. The gonophores are placed singly 011 the stolons or on
the hydranth stems, most frequently attached to the latter by a short stalk.

The distinguishing marks between Perigonimus and Bougainvillia, indeed, seem to be so in-
significant that the conclusion might be obvious that both genera should be united into one. The
Perigonimus polyp, when wholly extended, is very easily mistaken for a Bougainvillia. However, there
is an essential difference between the two genera which necessitates a separation. Their medusae
even belong to different families, the Bougamvillta-medusa.e being typical Margelidne, while Perigoni-
mus gives rise to Tiaridae (see Hartlaub 1913). As far as the nurse polyp is concerned, we must
notice the difference existing between the wholly naked Bougamvillia-polyp and the hydranth covered
with pseudohydrotheca of the Perigonimus-polyp. The pseudohydrotheca has been pointed out by sev-
eral authors and has been emphasized as generic character particularly by Broch (191 1). A closer
inquiry into this formation has been made by Hadzi(i9i3, 1914), who has studied it most thoroughly
in the Adriatic species, Perigonimus Corii Hadzi and Perigonimus Georginae Hadzi; the latter spe-
cies is very nearly related to Perigonimus rcpens (Wright). Hadzi points out that Perigonimus is
provided with a sort of hydrotheca, the essential substance of which is jellied and accordingly not
entirely parallel with the hydrotheca of the thecaphore hydroids. For this jellied polyp case, which
is, in its outer margin, connected with the ectoderm of the polyp, I, therefore, employ the denomina-
tion of "pseudohydrotheca", earlier employed for the chitinous false hydrothecae of Clal/irozoon. In the
case of Chlathrozoon, however, the formation seems to be quite different, and the denomination, on
that account, rather misleading; indeed, we had better employ the term of "false hydrothecae". Hadzi

52

HYDROIDA

calls our attention to the interesting fact that the polyps are basally attached to the pseudohydrotheca
by a whorl of small chitinous bodies similar to that met with in Halcciidae, Plumulariidae, Lafoeidae,
and Campanulariidae ; they actually attach the supporting lamella to the polyp case. Systematically,
however, hardly any particular importance can be attached to this character. The chitinous bodies
occur on the passage from the pseudohydrotheca to the hard periderm of the stem. Also the periderm
of the stem has, in most species of Perigonimus a jellied cover, to which a lot of foreign bodies fasten
themselves so as to give the colony a foul appearance.

The stinging cells in the tentacles of the Perigonimus-STpecies show attempts at an arrange-
ment by belts. But it is not here so pronounced as in the Eudendriidae and the thecaphore hydroids.
This criterion, together with the pseudohydrotheca, suggests that Perigonimus must be more nearly
related to the thecaphore hydroids than most other athecate hydroids.

Perigonimus repens (Wright) Allman.

1857 Eudendrium repens, Wright, Observations on British Zoophytes, p. 84, pi. 82, fig. 8—9.
1864 Perigonimus , Allman, On the Construction and Limitation of Genera among the Hy-

droida, p. 365.
nee 191 1 — , Broch, Fauna droebachiensis, p. 14.

From the reptant stolons proceed thin polyp stems, up to 5 mm. long, more rarely dichotomi-
cally divided so as to bear two polyps. The polyps are about 0.5 mm. long, broadly fusiform, with
4 — 12 tentacles placed in a whorl, and surrounded below the tentacles by a thin jellied pseudohydro-
theca, which is sometimes hardly observable. The polyp stems are wholly without rings, and all but
without wrinkles, and provided with a dark-coloured, but thin perisarc, which, on account of bottom
particles appendant, convey the impression of being granulous.

The gonophores are developed into free medusae; when breaking away, they have two ten-
tacles and a well-developed, solid umbrella. The gonophores are borne individually on stems 0.2 — 0.3
mm. long, proceeding from the hydranth stems; on one hydranth stem is generally developed one
gonophore at a time, sometimes a couple of gonophores simultaneously.

Material :

The Faroe Islands, Sorvaag. Depth 14— i6r/2 fath. (on Nucula nucleus).

Certainly it is not this species that is delineated and described by the name of Perigonimus
repens in Fauna Droebachiensis (Broch 1911). A comparison with the excellent drawings of the
species with Jaderholm (1909, Taf. I, Fig. 15 — 16), at once shows us the difference. The species
described and delineated from the Kristianiafjord has a stiff and robust structure; its perisarc is solid
and the colonies are open rhizocaulome formations; most probably the specimens in question should
have been referred to Perigonimus muscoides M. Sars. Perigonimus repens, on the other hand, has
thin closely set, irregularly curved polyp stems. Besides, the colonies from the Kristianiafjord bear on
the hydranth stems numerous gonophores without stalks, while the few gonophores of Perigonimus
repens are borne on distinct small stalks covered with perisarc.

HYDROIDA

53

Perigonimus refiens is a southern species which penetrates into our seas. It has been recorded
from the Mediterranean and the west coast of France, and occurs frequently in the sea round Great
Britain and Ireland. Already in the North Sea its occurrence is more straggling. In the Danish
waters and along the coast of Bohuslan it is still rather frequent. On the coast of Norway it is not
unfrequeutly met with in the Trondhjemfjord, where the fauna, on the whole, bears a southern char-
acter. But only once it has been found farther to the north, at Lofoten. Saemundsson (I911) re-
cords several questionable specimens from the west and the north of Iceland. But these localities
have to be confirmed. As a new locality must now be added the Faroe Islands. The species belongs
to the litoral resjion.

200 m. boom looom. , 2000m-

Text-fig. P. The distribution of Perigonimus repens in the Northern Atlantic Co localities needing further confir-
mation. — In the hatched region the litterature denotes a scattered although common occurence of the species).

Perigonimus abyssi G. O. Sars.
1874 Perigonimus abyssi, G. O. Sars, Bidrag til Kundskaben om Norges Hydroider, p. 96, pi. 5, Fig. 27—30.
191 1 ■ — sp., Kramp, Danmarks-Ekspeditionen til Gronlauds Nordostkyst, p. 363.

From the reptant stolons proceed unbranched polyp stems, which attain a length of 1.5 mm.
The polyps are about 0.5 mm. long, broadly fusiform, bearing 5—8, usually 7 tentacles in a whorl.
Below the tentacles the polyp is surrounded by a rather vigorous, wide, jellied pseudohydrotheca, which
is, however, often hardly visible on the polyp wholly extended. The polyp stems are irregularly and
strongly wrinkled, and have a dark-coloured, vigorous perisarc.

The gonophores are developed into free medusae, having, when deliberated, a vigorously
developed umbrella and four tentacles. The gonophores are developed on the polyp stems, to which
they are attached by a very short stalk. On the polyp stem arise one or two gonophores.

54

HYDROIDA

Material :

Greenland, Egedesminde (on Lepeta coeca).

The species has been found chiefly along the west coast of Scandinavia. It is likely to occur
much more frequently than might be believed from the scattered data. On account of its small
dimensions, and as, besides, it prefers settling on living, smaller molluscs, it too often escapes the
attention of the investigators of hydroids. Perigonimus abyssi has been found at Bohuslan and
on the west coast of Norway, from Stavanger as far as the Trondhjemfjord, at the depth of ioo
—600 metres. On the north side of Beeren Island it has been met with at the depth of 165

Text-fig. Q. The finds of Perigonimus aiyssi in the Northern Atlantic.

metres (Bonne vie 1899). In Arctic regions it may occur in considerably shallower waters. Thus the
German expedition to Spitzbergen in 1898 found the species in the Storfjord at the depth of between
o and 10 metres (Broch 1909), and certainly it is the same species that is recorded by Kramp (1911),
by the name of Perigonimus sp., from the depth of 20—40 metres at a couple of stations of the "Dan-
mark" Expedition. To the localities previously recorded must now also be added the west coast of
Greenland near Egedesminde. -- According to the data in hand, the species must be characterized as
Arctic and boreal (Text-fig. O).

Perigonimus roseus (M. Sars) Bonuevie.
1874 Rhizoragium roseum, M. Sars in: G. O. Sars, Bidrag til Kundskaben om Norges Hydroider, p. 96.
1892 Garvcia groenlandica, Levinsen, Meduser, Ctenophorer og Hydroider fra Groulauds Vestkyst, p. 13.
1898 Perigonimus rose/is, Bonuevie, Neue norwegische Hydroiden.
1911 Garveia groenlandica, Kramp, Danmark-Ekspeditioneu til GronlandsNord6stkyst,p.363, pi. XXV, fig. 6.

HYDROIDA

55

From the reptant stolons proceed polyp stems up to 12 mm. long, generally unbranehed; more
rarely 2 — 4 polyp stems proceed from a common trunk, 1 — 2 mm. high. The polyps attain a length
of 0.7 mm., and are fusiform, with 6 — 12 tentacles placed in a whorl. Below the tentacles the polyp
is surrounded by a psendohydrotheea, which it is very difficult to observe on the polyp when wholly
extended. In general it is jellied and vigorously developed. The polyp stems are, particularly in their
proximal part, irregularly wrinkled.

The very large gonophores show no medusoid structure; they are attached to the reptant sto-
lons by a short stem.

Material :

Greenland (Lille Hellefiskebauke) (the original specimen of Garveia groenlandica Levinsen).

An examination of the original specimen of Garveia groenlandica shows no difference at all
from Norwegian specimens of Perigonimus rosats. The species are no doubt identical. If we compare
Kramp's drawing of Garveia groenlandica (1911, pi. XXV, fig. 6) with Jaderholm's figure of Pe-
rigoi/ii/uts rosats (1909, Taf. Ill, Fig. 7), there may, at the first glance, seem to be some points of
difference. Thus the stems of the specimen mentioned by Kramp are much shorter. But this character
proves of little significance if we compare the specimen with a larger colony, where, as a matter of
fact, the length of the polyp stems varies greatly. A greater stress might, on the other hand, be laid
on the apparently great difference between the psetidohydrothecae as represented in the two figures.
However, much depends on the contraction of the polyps and on the state of preservation, as is plainly
to be seen by an inquiry into a larger material. I have several times had the opportunity of observ-

20om. 600 m. tooom. 2000m.

Text-fig. R. The occurence of Perigonimus roseus in the Northern Atlantic.
(In the hatched region the occurence according to the litterature is common allthough scattered).

56

HYDROIDA

ing, in larger colonies of Perigommus, individuals with psendohydrothecae bulging even more loosely
round the shrunken and contracted polyps than that rendered in Kramp's drawing, while, at the
same time, in extended polyps in the same colony, a superficial view fails to notice the presence of
this formation (Broeh 1911, fig. 12). The intermediate state represented by Jaderholm is the com-
monest observed in preserved colonies. Still one point of difference might seem to remain, the chiti-
uous cup in which the gonophore, in Garvcia groenlandica, is resting when it is about to empty its
ripe contents. This cup, or rather this remnant of the flayed-off external periderm cover of the gono-
phore, is, however, frequently observed also in the female gonophores of typical Perigonivius roseus,
in which hitherto no particular importance has been attached to this character. Accordingly, we have
to include Garvcia groenlandica as a synonyme under Perigonimtis roseus.

The chief occurrence of the species is attached to the middle and the lower parts of the litoral
region of the boreal waters. It occurs rather frequently from Bohuslan as far as Lofoten, generally
attached to stalks of Tubularia indivisa. However the species also penetrates far into Arctic waters,
and has been recorded from the White Sea and as far to the north as Nova Zembla. It has previ-
ously been recorded from Greenland (Jaderholm 1909), where now also Lille Hellefiskebanke, Fiske-
nes (West Greenland), and Daumarks Havu (East Greenland) have to be added to its localities
(Text-fig. R).

Family Eudendriidae.

Hydroids forming colonies, the polyps of which are provided with a single whorl of filiform
tentacles. The proboscis is capitate, placed with a narrow base on the broad polyp body above the
tentacle whorl; the stinging cells of the tentacles are small and rodshaped. Also larger stinging cells,
narrowly oval, occur, particularly in the specific stinging organs of the polyp. The stinging cells of the
tentacles are arranged in very distinctive transverse belts. The polyps are wholly naked. The endoderm
of the polyp is differentiated into two portions, an oral portion, consisting of small-nucleated, indifferent
cells, among which occur some mucous gland cells, and the proper gastral portion. The limit is formed
by the tentacle whorl. The tentacles lack a central cavity. The colonies have no calcareous skeleton.

Nearly all investigators of hydroids have distinguished the Eudendriidae as a family of their
own. To this Levinsen (1892) forms an exception, considering the arrangement of the tentacles in
a single whorl round the polyp as indicative of so near a relationship to the Bougainvilliidae that he
unites the two families into one. However, the Eudendriidae, in their structure of the polyps, show,
as compared to other athecate hydroids, such peculiarities that we are forced to distinguish them as
a family of their own. In the first place are obvious the broad structure of the polyp body and the
capitate proboscis, placed with a narrow base above the well defined tentacle portion. In this cha-
racter the polyps bear a strongly marked resemblance to the theeaphore Campanulariidae. This like-
ness is the more interesting because, in the more delicate structure of the polyp of the Eudendriidae,
several points of resemblance to the theeaphore hydroids are demonstrable. Thus the stinging cells of
the tentacles of Eudendriidae, as well as those of the theeaphore hydroids, are arranged in well defined

HYDROIDA ry

transverse belts. This peculiarity we find slightly indicated even in some Bougainvilliidae. Bnt only
in the Eudendriidae it has become a character plainly distinctive. Further, the endoderm in the well
defined hypostome shows the same structure as in the thecaphore hydroids, and is more strongly differ-
entiated than in the Bougainvilliidae, the indifferent cells having gained the ascendency, and the number
of the mucous gland cells having been reduced to a minimum. Whether these peculiarities are indic-
ative of a nearer relationship between the Eudendriidae and the thecaphore hydroids, is a question
which it would here be out of place to enlarge upon.

The Eudendriidae, with their frecpiently dimorphic development of the stinging cells, also pre-
sent a parallel to the Stylasteridae. Besides the small rodformed stinging cells characteristic of all
Fib/era, we also find in several species larger narrowly oval ones, bearing a strong resemblance to
those of the Stylasteridae. The latter are large, but of the same shape as the small stinging cells of
Myriothela. We probably here face a phenomenon of convergence, the reason of which, however, at
the present stage of our knowledge of the biology of the Coelenterata, we cannot account for with
any certainty. Wherever the larger stinging cells occur in the Eudendriidae they are accumulated in
particular stinging organs.

Eudendrium Ehrenberg.

Upright colonies with branched hydrocaulus. The polyps are broad and distinctly set off from
the stem, which is covered with a vigorous chitiuous perisarc. The polyp has a single whorl of fili-
form tentacles. Above the tentacle whorl the polyp is suddenly tapering and ends into a capitate or
trumpetshaped proboscis, which is seated, with a narrow base, above the tentacle whorl. The gono-
phores are developed on normal or reduced polyps, or placed singly on the branches.

Kiihn (1913, p. 48) states that the polyp tentacles of Eudendrium "nach einander vorsprossen
und dadurch sich als Angehorige verschiedener Wirtel zu erkennen geben". Later on (1. c. p. 247) he
again mentions this peculiarity as a refutatory argument against the adoption of a nearer relationship
to the thecaphore hydroids; in the passage last quoted he apparently bases his opinion essentially on All-
man (1872). A closer inquiry, 011 new material, gave no hold to the statement of A 11 man and Kiih 11 that
the tentacles should appear successively. In the numerous colonies examined of Eudendrium rameum
(Pallas) and Ezidendrium Wrighti Hartlaub it could be ascertained that all the tentacles appear
simultaneously. This suggests that the observations of Allman may rather depend on accidental cir-
cumstances, and that no special importance must be attached to them as reminiscences of manyrowed
tentacle-whorls of the ancestors or as proofs of a nearer or remoter relationship to the Bougainvil-
liidae or to the thecaphore hydroids.

Eudendrium rameum (Pallas) Thompson.
1766 Tubular ia ramea, Pallas, Elenchus zoophytorum, p. 83.
1844 Eudendrium rameum, Thompson, Report on the Fauna of Ireland, p. 283.
1887 ramosum, Bergh, Karahavets goplepolyper, p. 332.

The Ingolf-Expcdition. V. 6.

58

HYDROIDA

1908 Eudendrium caricum, Jaderholm, Die Hydroiden des Sibirischen Eismeeres, p. 5, Taf. I, Fig. 4,

Taf. II, Fig. 1.
191 1 rigid 'it 111 .' + Eudendrium ramosum, Sseiimiidsson, Bidrag til Kiuidskaben om de is-

landske Hydroider, p. 74—75.

The strongly and irregularly branched colonies have a fascicled main stem, and attain a height
of 200 mm. The small branches are annnlated immediately above their rise from the mother branch,
but are elsewhere smooth. The polyps have abont 20 tentacles. There is no particularly developed
ring of stinging cells round the tentacles or the polyp body. The colonies have no particular sting-
ing organs.

The gonophores are styloid. The male gonophores have 2 — 4 chambers and are seated round
the base of fully developed polyps. The female gonophores are pear-shaped, and are borne on the
bodies or the hydrocauli of polyps that may either be fully developed, or somewhat smaller than the
sterile polyps, or entirely reduced. The spadix is unbranched.

Material:

"Ingolf" St. 21. 58°oi' N. lat. 44°45' long W. Depth 1330 fath. 2°4 C.

- 31. 66°35' - - 55°54' - - 88 i°6 -

- 44. 6i°42' - - 9°36' - - 545 4°8 -

Greenland : Davis Strait Depth 80 — 100 fath.

Henry L,and, East Greenland — 20 —

Cape Tobin — 57 —

Iceland: 6 miles west of Iceland — 22 —

Stykkisholm — 20—30 —

Faxebugt, 16 miles N.E. of Akranes ^Eudendrium ramosum") — 26 — 30 —

Vestman Islands {"Eudendrium rigidum f") 30 —

The Faroe Islands: Stokkeu 2 engl. miles S 22 E 55 —

"Thor" 6i°i5' N. lat. 9°35' W. long. 872 m.

"Diana" 6i°4o' - - 7^0' - — — 135 fath.

Store Fiskebanke (Large fishing-bank) 57°7' - - 2°4o' E. — 37 —
The Kara Sea, "Djimphna".

This common northern species has, no doubt, frequently been confused with the southern spe-
cies Eudendrium ramosum (Din.), which, in fact, is rather rare in our northern seas. Assuredly enough,
nearly all the statements of the occurrence of the last-mentioned species in Arctic waters, are to be
regarded as referring to specimens of Eudendrium rameum, the appearance of which varies greatly
indeed. It has already been pointed out by Kramp (1911) that the species Eudendrium caricum from
the Russian polar expedition, described by Jaderholm (1908), is, in fact, founded on specimens of
Eudendrium rameum. Surely enough, it is the same species which is recorded by Bergh (1887) now
as Eudendrium rameum and Eudendrium ramosum, now as Eudendrium sp.

The species has a circumpolar distribution, and appears, from the statements of literature, to be a

HYDROIDA

59

200 m. boom. ... tooom. 2000m.

Text-fig. S. The habitat of Eudendrium rameum in the Northern Atlantic.

perfect cosmopolite. It occurs frequently everywhere in the middle and deeper parts of the litoral region
of the northern seas (Text-fig. S), and may, exceptionally, as in the "Ingolf" st. 21, also penetrate far
down into the abyssal reo-ion.

Eudendrium ramosum (Linne) Ehrenberg.
1758 Tiihulan'a ramosa, Linne, Systema naturae, ed. X, p. 804.

1834 Eudendrium ramosit?n, Ehrenberg, Beitrage zur physiologischen Kenntnisse der Corallenthiere,

p. 296.
nee 1887 — , Bergh, Karahavets Goplepolyper, p. 332.

nee 1911 — — , Saemundsson, Bidrag til Kundskaben om de islandske Hydroider, p. 74.

The strongly branched colonies show an almost quite regular, alternating arrangement of
the small branches. The main stem is fascicled. The small branches are annulated above their rise
from the mother branch, but are elsewhere quite smooth. The polyps have about 20 tentacles. The
stinging cells are not accumulated in any particular main ring round the tentacles or the polyp body.
The colony has no particular stinging organs.

The gouophores are styloid. The male gonophores have 2 — 3 chambers and are seated round
entirely atrophied polyps with short hydrocauli. The female gouophores are pear-shaped and borne
on the bodies or on the stems of polyps which are either fully developed or somewhat reduced as
compared to the sterile polyps. The spadix is unbranched.

Material :

Southeastern Iceland: (Honing) 1898. — Depth 52 — 49 fath.

8*

6o HYDROIDA

The species Eudendrium ramosum (Pallas), Eudendrium rameum. (Pal la s), and Eudendrium race-
mosum (Cavolini) are very nearly related to each other, and sterile colonies of the three species are often
hardly distinguished with certainty. While in Eudendrium r&meum the male gonophores are borne on
polyps fully developed, they are seated, in Eudendrium ramosum and Eudendrium racemosum round polyps
wholly reduced. This conformity of the two last-mentioned species, the homogeneous structure of their
colonies, and several other features common to them, which struck me during my inquiry into the Adriatic
hydroids (1912), really led me to consider, though with some doubt, Eudendrium racemosum as a synonyme
of Eudendrium ramosum. This supposition, however, is hardly right. By the liberality of Dr. C. Dehnho-
fer at Innsbruck I have afterwards had the opportunity of examining more closely unquestionable colo-
nies of Eudendrium racemosum from Triest, and of recognizing in these the characteristic criteria distin-
guishing this species from Eudendrium ramosum. Occasionally are found developed in the polyp of Eu-
dendrium racemosum peculiar organs which are not traceable in other species of the genus, and which, like
analogous organs in other hydroids, have to be designated as "nematophores" (cp. Weismanu 1882).
Elsewhere the presence or the absence of these formations is looked upon as a generic character among
the hydroids. But this view is here hardly justifiable, as in Eudendrium racemosum the nematophores occur
quite irregularly and are rather rare; in some colonies they are even entirely wanting, and such colonies,
when sterile, or when only male individuals occur, cannot be distinguished with certainty from Eudendrium
ramosum. — The other distinguishing mark between the two species is the spadix of the female gono-
phores. While, according to the descriptions in hand, the spadix of Eudendrium ramosum is unbranched,
that of Eudendrium racemosum is, on the contrary, bifurcate or divided into three branches, embracing
the ovum like a claw (s. Broch 1914 Stylasteridae p. 24, Text-fig. I) I regret that I have not succeeded
in getting hold of fertile female colonies of Eudendrium ramosum, so as to be iinable to give a draw-
ing, from new material, of the female gonophore of this species.

From the statements above it is clear that Eudendrium ramosum has most probably been
several times confused with Eudendrium racemosum. On the other hand, as I have earlier pointed
out, a confusion with Eiidendrium rameum, particularly from the northern seas has also often taken
place, and the geographical data presently in hand as to Eudendrium ramosum are, therefore, of most
questionable value. A closer inquiry into the colonies from Faxebugt (Iceland) recorded by S a; m unds-
son (191 1) as Eudendrium ramosum, shows that we here really face typical Eudendrium rameum.
However, the single specimen of the species which is in hand, shows us that in wanner layers of
the Atlantic it may occur as far to the north as Iceland. The occurrence of the species in the northern
Atlantic regions, however, has yet to be more closely accounted for.

Eudendrium Wrighti Hartlaub.

1859 Eudendrium arouscu/a, Wright, Observations on British Zoophytes, p. 113, pi. 9, fig. 5 — 6.
1905 Wrighti, Hartlaub, Die Hydroiden der magalhaensischen Region, p. 547.

The strongly and irregularly branched colonies have a fascicled main stem, and attain a height
of 60 mm. The small branches are annulated above their rise from the mother branch, but are else-
where smooth. The polyps have a large number of tentacles. The tentacles have no particularly

HYDROIDA

6l

distinct main ring of nematocysts. On the other hand, there is round the polyp body, at its base, a
distinctive girdle of large stinging cells. Otherwise, the colony has no particular stinging organs.

The gonophores are styloid. The male gonophores have two chambers with a well marked
accumulation of stinging cells distally, and are densely clustered on short stems perpendicularly
placed on the trunk. Female gonophores are unknown.

Material:

The Faroe Islands: Traugisvaag, on roots of Laminaria.

The species was first described by Wright (1859) by the name of Eudendrium arbuscula from
the Firth of Forth. However, another Eudendrium had been previously described by d'Orbigny

200 m. .....600m. ._ ....looom. 2000m.

Text-fig. T. The occurence of Eudendrium Wrighti • and Eudendrium annulatum ▲ in the Northern Atlantic.
(The vothed coastal parties denote a scattered occurence of Eudentium Wrighti according to the litterature).

(1839) by the name of Tubular ia arbuscula from Patagonia, and even though it will be questionable
whether the species of d'Orbigny can be reidentified, we are no doubt right to follow Hartlaub
(1905) and abandon the name of arbuscula for the northern species. Here we, therefore, adopt the
denomination of Hartlaub, Eudendrium Wrighti.

Eudendrmm Wrightiis an absolutely littoral species, the occurence of which seems to be restricted
to the zone of the Laminaria. It occurs quite frequently from Bohuslan as far as towards the Trond-
hjemfjord, and it is peculiar, therefore, that its female gonophores have not yet been pointed out. The
species is quite common at the British Isles (s. the Text-fig. T), and it has also been recorded from the
Mediterranean. Eudendrium Wrighti is, therefore, likely to be characterized as an Atlantic species of
southern character, which is able to penetrate into the northern seas as far as the Trondhjemfjord.
The Faroe Islands have now to be added to the localities where the species has been found.

62

HYDROIDA

Eudendrium annulatum Normann.

1864 Eudendrium annulatum, Norman, On undeseribed British Hydrozoa, Actinozoa, and Polyzoa, p.

83, Pi- 9> fig- r— 3-

The strongly and irregularly branched colonies have a fascicled main stem, and attain a height
of 100 mm. All the smaller branches are densely annulated everywhere. The polyps have 16—20
tentacles. There are no particular accumulations of stinging cells on the tentacles or on the polyp
body, and the colony has no particular stinging organs.

The gonophores are styloid. The male gonophores have one chamber with an accumulation of
stinging cells distally, and are densely grouped on short stalks perpendicularly placed on the stem.
The female gonophores have an unbranched spadix aud form grape-like clusters round polyps entirely
atrophied.

Material:

Greenland: Sukkertoppen (without particular data).

Iceland: Vestmau Island, on the stems of Tubularia hidivisa.

Eudendrium annulatum seems to occur rather sparsely, but apparently on the whole prefers
the littoral parts of the boreal seas. However, among the localities of the species are also recorded
the Cape Verde Islands (Quelch 1885), and with some doubt Cape Town (Ritchie 1907). On the
west coasts of Scandinavia the species has been met with here and there from Bohuslau as far as
Vadso, and it even occurs in the Murman Sea. It has been found near Jan Mayen and the Shetlauds,
and specimens occur from the south of Iceland and from West Greenland.

Eudendrium capillare Alder.
1856 Eudendrium capillare, Alder, A notice of some new Genera and Species of British Hydroid Zoo-
phytes, p. 355, pi. 12, fig. 9—12.

The strongly and irregularly branched colonies have a simple unfascicled main stem, and
attain a height of 30 mm. The branches show a few rings immediately above their rise. But else-
where they are smooth. The polyps have 20—30 tentacles. There are no particular accumulations of
stinging cells on the tentacles or on the polyps. The colonies have no particular stinging organs.

The gonophores are styloid. The male gonophores have two chambers with an accumulation
of stinging cells distally, aud are placed in a whorl round entirely atrophied polyps or, more rarely,
round strongly reduced polyps, the stems of which rise from the hydrocaulus or the hydrorhiza. The
female gonophores occur in the same manner; they are pear-shaped with unbranched spadix.

Material:

Greenland: Store Hellefiskebanke . . . Depth 28 fath.

Iceland: Stykkisholm . . . Depth 30 fath.

The Faroe Islands: between Nolso and Gstnses . . . Depth 100 fath.

The specimens from the "Store Hellefiskebanke" offer a great interest, the male gonophores

HYDROIDA

63

200m. 600m. 1000m. 2ooom.

Text-fig. U. The distribution of Eudendrium capillarc in the Northern Atlantic.
(The hatched coastal region indicates a scattered occurence according to the litterature).

being borne by diminutive polyps. It accordingly appears that the fertile polyps of the species are
not always wholly atrophied, as has hitherto been generally snpposed.

The distribution of Eudendrium capillarc is extremely wide, almost quite cosmopolitan. It very
frequently occnrs in the northern seas (Text-fig. U); however, already in the Norwegian Sea and
along the west coast of Norway its occurence becomes less frequent, and it does not penetrate very
far into the Arctic regions. The species belongs to the middle parts of the littoral region.

LITERATURE

i. Agassiz, L- (i860 — 1S62): Contributions to the Natural History of the United States of America, Second Monograph,
vol. 3 and 4. Boston.

2. Alder, J. (1856): A Notice of Some New Genera and Species of British Hydroid Zoophytes. (Ann. and Mag. of nat.

Hist. Ser. 2, vol. 18). Loudon.

3. Allman, G. J. (1864): Notes on the Hydroida. (Ann. and Mag. of nat. Hist. Ser. 3, vol. 14). London.

4. — (1864): On the Construction and Limitation of Genera among the Hydroida. (Ann. and Mag. of nat. Hist. Ser. 3,

vol. 13). London.

5. — (1S72): A Monograph of the Gymnoblastic or Tubularian Hydroids. London.

6. — (1S76): Diagnoses of New Genera and Species of Hydroids. (Journ. Linnean Soc. (Zoology), vol. 12). London.

7. — (1S77): Report on the Hydroida, Collected during the Exploration of the Gulf Stream by L. F. de Pourtales. (Mem.

Mus. Comp. Zool. Harvard College, vol. 5). Cambridge.

8. Babic, K. (1904): Uebersicht der Hidroidpolypen des adriatischen Meeres. (Glasnih hrv. uaravoslovu. drustva, vol. XV).

Zagreb.

9. Bedot, M. (1901 — 12): Materiaux pour servir a l'Histoire des Hydro'ides. (Rev. Suisse de Zool. Vol. 9, 13, iS and 20).

Geneve.

10. Behner, A. (1914): Beitrag zur Keuutnis der Hydromedusen. (Zeitschr. wiss. Zool., Bd. 1 1 1). Leipzig.

11. v. Beneden, P. J. (1S41): Recherches sur la structure de l'oef dans 1111 nouveau genre de Polype (genre Hydractinie).

(Bull. Acad. sc. Bruxelles, vol. 8). Bruxelles.

12. — (1844): Recherches sur l'embryogenie des Tubulaires et l'histoire naturelles des differents genres de cette famille

qui habitent la cote d'Ostende. (Nouv. Mem. Acad. Bruxelles, vol. 17). Bruxelles.

13. Bergh, R. S. (1887): Goplepolyper (Hydroider) fra Kara-Havet. (Dijmphna-Togtets zoologisk-botaniske Udbytte). Kjo-

benhavn.

14. Billard, Arm. (1906): Mission des pecheries de la cote occidentale d'Afrique. (Actes Soc. Linn. Bordeaux, Vol. 61).

Bordeaux.

15. Boeck, C. (i860): Tubularie fra Belsund paa Spitzbergen — Tubularia regalis. (Vidensk. Selsk. Forhandlinger, Aar 1S59).

Christiania.

16. Bonuevie, K. (1S98): Zur Systematik der Hydroiden. (Zeitschr. wiss. Zool. Bd. 63). Leipzig.

17. — (1898): Neue norwegische Hydroiden. (Bergens Mus. Aarbog). Bergen.

18. — (1899): Hydroida. (Den Norske Nordhavs-Expedition 1876— 1878. XXVII. Christiania.

19. Broch, Hj. (1903): Die von dem norwegischcn Fischereidampfer "Michael Sars" in den Jahren 1900— 1902 in dem Nord-

meer eingesammelten Hydroiden. (Berg. Mus. Aarbog). Bergen.

20. — (1909): Die Hydroiden der arktischen Meere. (Fauna arctica, Bd. V). Jena.

21. — (1911): Fauna droebachiensis. I. Hydroider. (Nyt Mag. Naturvid. Bd. 49). Kristiania.

22. — (1914): Hydrozoa benthonica. (Beitrage zur Kenntnis der Meeresfauna Westafrikas). Hamburg.

23. — (1914): Stylasteridae. (The Danish Ingolf-Expedition, Vol. V). Copenhagen.

24. (1915): Hydroiduntersuchungen. IV. Beitrage zur Kenntnis der Gonophoren der Tubulariiden. (Det kgl. norske

Vidensk. Selsk. Skr. 1914). Trondhjem.

25. Clark, H. J. (1865): Mind in nature; or the orgine of life, and the mode of development in animals. New-York.

26. Ehrenberg, C. G. (1834): Beitrage zur physiologischen Kenntniss der Corallenthiere im Allgemeineu und besonders des

rothen Meeres, nebst einem Versuche zur physiologischen Systematik derselben. (Abhandl. d. K. Akad. d. Wiss.
zu Berlin 1S32). Berlin.

HYDROIDA

65

27. Ellis, J., and Solander, D. (1786): The natural history of many curious and uncommon Zoophytes, collected from

various parts of the Globe. London.

28. Fabricius, O. (1780): Fauna Groenlandica. Hauuioe et Lipsia?.

29. Fenchel, A. (1905): Ueber Tubularia larynx Ellis iT. coronata Abildgaard). Revue Suisse de Zool Vol. 131. Geneve

30. Fewkes, J. W r 88 1 j : Report on the results of the dredging operations under the supervision of Alexander Agassiz

in the Caribbean Sea. (Bull. Mus Comp. Zool. Harvard Coll. Vol Villi. Cambridge.

31. Fleming, J. (1S2S1: A History of British animals. Edinburgh.

32. Forskal, P. (17751: Descriptiones animalium . . . qua; in itinere orientali observavit. Haunia2.

33. Giard. A. 1 1899 : Sur 1'etSologie du Campanularia calyculata Hincks. (C. R. Soc. Biol. Paris. Ser 10, Vol. 5. Paris.

34 Hadzi, J. 119131: Poredbena hidroidska istrazivanja II. Perigonimus corii sp. u i Perigonimus georginae sp. n. (Rada.

Jugoslav, akad. znau. i umjetn. knj. 200). Zagreb.
35- — (I9T4): Vergleichende Hydroidenuntersuchungen II. [Extract in the German language of the preceding paper]. (Bull

d. Travaux de la Classe d. Sci. Math et Natur. fasc 1). Zagreb.

36. Hartlaub, C. (1905): Die Hydroiden der magalhaensischen Region und chilenischen Kiiste. (Zool. Jahrb. Suppl. 6)-

Jena.

37. (1907): Craspedote Medusen. I Teil, 1. Liefg., Codoniden und Cladonemiden. (Nord. Plankton. Bd. 6). Kiel und

Leipzig.
3S. (1913): Craspedote Medusen. I. Teil. 3 Liefg., Tiaridae. (Nord. Plankton. Bd. 6). Kiel und Leipzig.

39. Hincks, Th. (1S6S): A History of the British Hydroid Zoophytes. London.

40. Jaderholm, E (1902): Die Hydroiden der schwedischen zoologischen Polarexpedition 1900. (Bih. Kgl. Vet.-Akad. Handl

Bd. 28). Stockholm.

41. — (1905): Hydroiden aus antarktischen und subantarktischen Meereu. Wissensch. Ergebn. d schwed. Siidpolar-

Exped. 1901 — 1903. Bd. 5). Stockholm.

42. — (1908): Die Hydroiden des Sibirischeu Eismeeres, gesammelt von der russischen Polar-Expedition 1900 — 1903. (Mem.

de l'Acad. Imp. des Sci.). St. Petersbourg.

43. — (1909): Northern and Arctic Invertebrates in the Collection of the Swedish State Museum. IV. Hydroiden. (Kgl.

Svenska Vet.-Akad. Handl. Bd. 45 . Uppsala & Stockholm.
44 Johnston. G. (1847): A History of the British Zoophytes. London.

45. Kramp, P. L. (1911): Report on the Hydroids collected by the Danmark Expedition at North-East Greenland. (Dan-

mark-Eksped. til Gronlauds Nordostkyst 1906 — 1908, Bd. V). KObenhavn.

46. — (19131: H)'droids collected by the "Tjalfe" Expedition to the West Coast of Greenland in 190S and 1909. (Vidensk.

Meddel. fra Dansk naturh. Foreu. Bd. 66). Kobenhavn.

47. — U914): Conspectus Faunse Groenlandica; Hydroider. (Meddel. oni Gronland XXIII). Kobenhavn.

48. Ktihn, A (1910): Die Entwickelung der Geschlechtsiudividuen der Hydromedusen. Studien zur Ontogenese und Phylo-

genese der Hydroiden II. (Zool. Jahrb. Vol. 30. Anat. 1. Jena.

49. — (1913): Entwickelungsgeschichte und Verwandtschaftsbeziehungen der Hjdrozoen. I. Die Hydroiden. (Ergebn.

und Fortschr. der Zool. Bd. IV). Jena.

50. Levinsen, G. M. R. 11893 : Meduser, Ctenophorer og Hydroider fra Gronlands Vestkyst. (Vidensk. Meddel. fra den

naturhist. Foren. i Kjobenhavn for 1892). Kjobenhavn.
jr. Lin lie, C. (1758): Systema Naturas. Ed. 10. Hohniae.

52. Loman, J. C. C. 18891: Hydropolypen mit zusammengesetztem Coenosarkrohr. Tijdschr. Xederl. dierkund. Veren. Ser. 2,

Vol. 21. Amsterdam.

53. Loven, S. (1835): Bidrag til Kannedomen af Slagtena Campanularia och Syncoryna. (Kgl. svenska Vet.-Akad. Handl.

for Ar 1835). Stockholm.

54. v. Lorenz, L. (1886): Polypomedusen von Jau Mayen. Die Oesterr. Polarstation Jan Mayen, Bd. III). Wien.

55. Liitkeu, C. 11850): Nogle Bemeerkninger om Medusernes systematiske Inddeling, navnlig med Hensyn til Forbes's History

of brilish naked-eyed Medusa. (Vidensk. Meddel. fra den Naturh. Foren. i Kjobenhavn for 1850. Kjobenhavn.

56. v. Marenzeller, E. E. (1878): Die Coelenteraten, Echinodermen und Wurmer der K. K. Oesterreichisch-Ungarischen

Xordpol-Expedition. (Denkschr. d. K. Akad. d. Wissensch. Math.-Naturw. Classe. Bd. 35). Wien.

57. Mayer. A G. 119101: Medusae of the world. Washington.

58. Mereschkowsky, C. (1877): On a new genus of Hydroids from the White Sea, with a short description of other new

Hydroids. (Ann. and Mag. nat. Hist. Ser. 4, Vol. 20). London.

The Ingolf-Expedition. V. 6. 9

66 HYDRO I DA

59. Miiller, O. F. 11777): Zoologia? Danica?. Fasc. r. Haunire.

60. Nordgaard, 0. (1912): Bryozoaires. Due d Orleans, Canipagne arctique de 1907). Bruxelles.

61. Norman, A. M. (1S64): On vmdeseribed British Hydrozoa, Actiuozoa, and Polyzoa. (Ann. and Mag. nat. Hist. Ser. 3,

vol. 13). London.

62. (1S65': On Meroiia, an undescribed genus of British Hydrozoa. (Ann. and Mag. nat. Hist. Ser. 3, vol. 15. London.

63. d'Orbiguy, A. (JS34— 46): Voyage dans l'Amerique ineridionale ... execute dans le cours des annees 1826 — 1833. Vol. 5. Paris.

64. Pallas, P. S. (1766): Elenchus zoophytorum. Hagae-Comitum.

65. Poche, F. (1914): Das System der Coelenterata. (Archiv fiir Naturgesch. Jahrg. So, Abt. A). Berlin.

66. Quelch, J.J. (1SS5): On some Deep-Sea and Shallow-water Hydrozoa. (Ann. and Mag. nat Hist. Ser. 5, Vol. 16:. London.

67. Ritchie, J. (1907): The Hydroids of the Scottish National Antarctic Expedition. (Transact. Roy. Soc. Edinb. Vol. XLV).

Edinburgh.

68. Sars, G. O. (1S74;: Bidrag til Kuudskaben om Norges Hydroider. (Forhaudl. i Vid--Selsk. i Christiania 1S73). Christiania.

69. Sars, M. (1835): Beskrivelser og Iagttagelser over nogle mierkelige eller live i Havet ved den Bergenske Kyst levende

Dyr af Polyperues, Acalephernes, Radiaternes, Anuelidernes og Molluskernes Classer, med en kort Oversigt over
de hidtil af Forfatteren sammesteds fundne Arter og deres Forekonimeu. Bergen.

70. (1846): Ueber die Fortpflanzungsweise einiger Polypen {Syncoryna, Podocoryna% Perigonimus, Cytais). (Fauna littoralis

Norvegise. 1. Heftej. Christiania.

71. — (1S51): Beretuing om en i Sommereu 1849 foretagen Zoologisk Reise i Lofoten og Finmarken. (Nyt Mag. for Na-

turvid. Bd 6) Christiania.
72- (1859,: Om AmmeslEegten Corymorpha, dens Arter, samt de af disse opammede Meduser. (Forhandl. i Vidensk.-

Selsk. i Christiania 185S . Christiania.

73. — (1S77): Nye og mindre bekjendte Coeleuterater. (Fauna littoralis Norvegiae, Part 3). Bergen.

74. Schneider, K. C. (1902): Lehrbuch der vergleichenden Histologie der Tiere. Jena.

75. Schmidt, O. (1852): Handatlas der vergleichenden Anatomic Jena.

76. Stechow, E. (1912): Hydroiden der Miinchener Zoologischen Staatssammlung. (Zool. Jahrb. Bd. 32, System.). Jena.

77. — (1913): Hydroidpolypen der japanischen Ostkiiste. II. Teil. (Abh. math.-phys. Klasse der K. Bayer. Akad. Wiss.

III. Suppl.-Bd.). Miinchen.

78. Steenstrup, J. (1842): Om Forplantning og Udvikling genuem vexlende Generationsnekker, en sseregen Form for Op-

fostringen i de lavere Dyreklasser. Kjobenhavn.

79. - (1854): En ny og tropisk Art af Smaagoplernes Ammesltegt: Corymorpha Sars (Corymorpha Januarii Stp.). — (Vi-

densk. Meddel. naturh. Forening i Kobenhavn for 1S54). Kobenhavn.

80. Swenauder, G. (19041: Uber die Athecaten Hydroiden des Droiitheimfjordes. (Det Kgl. norske Vidensk. Selsk. Skrifter

1903). Trondhjem.
Si. S;emundsson, B. (1S99): Auliscus Quicker, en ny Goplepolyp med frie Meduser. Zool. Meddel. fra Island. V. (Vidensk.
Meddel. naturhist. Foren. i Kobenhavn 1899). Kobenhavn.

82. (1902): Bidrag til Kuudskaben om de islaudske Hydroider. (Vidensk. Meddel. naturhist. Foren. i Kobenhavn 1902).

Kobenhavn.

83. — (1911): Bidrag til Kuudskaben om de islaudske Hydroider. II. (Vidensk. Meddel. naturhist. Foren. i Kobenhavn

191 1). Kobenhavn.

84. Torrey, H. B. (1907): Biological Studies on Corymorpha. 2. The Development of C. palma from the egg. (Univ. Cali-

fornia Publ. Zool., vol. 3 1. Berkeley.

85. Vanhoffen, E. (1909): Die Hydroiden der deutschen Siidpolar-Expedition 1901— 1903. (Deutsche Siidpolar-Expedition

1901—1903, Bd. XI, Zool. Bd. III). Berlin.
S6. Wagner, .1. (1890): Recherches sur l'organisation de Monobrachium parasiticum Merej. (Arch. Biol., Vol. io").
87. Weismann, A. (1882): Uber eigenthumliche Organe bei Eudeudrium racemosum Cav. (Mittheil. Zool. Station zu Nea-

pel. Bd. 3). Leipzig.
SS. Winther, G. (1880): Fortegnelse over de i Danmark og dets nordlige Bilande fundne hydroide Zoophyter. (Naturhist.

Tidsskr, vol. 12). Kobenhavn.

89. Wright, T. S. (1S57): Observations on british Zoophytes. (Edinb. new philos. Journ. New Ser. Vol. 6'. Edinburgh.

90. 1S59): Observations on british Zoophytes. (Edinb. new philos. Journ. New Ser. Vol. 10). Edinburgh.

Plate I.

Plate I.

Fig. i. Nematocyst from the tentacle of Monocoryne gigantca. Delafields haematoxyline — Iron
ammonium sulfate. ^5°/^

2. Nematocyst from the tentacle of Coryne Lovc'ni. Boehmers haematoxyline — Iron ammonium
sulfate. '75°/,.

3. Nematocysts from the tentacle of Myriothela phrygia, a: of the general, ovoid type, b: of
the rarer, narrow type. Delafields haematoxyline — Iron ammonium sulfate. ^i°\x.

— 4. Nematocyst from the tentacle of Tubularia indivisa. Delafields haematoxyline — van Giesson.

175°^.

5. • Nematocyst from the tentacle of Clava multicornis. Delafields haematoxyline — Iron ammo-

nium sulfate, '^so/j.

6. Nematocyst from the tentacle of Bougainvillia ramosa. Delafields haematoxyline — Iron
ammonium sulfate, ^so/j.

7. Nematocysts from Eudcndrium Wrighti, a: small type from the tentacles, b: larger type
from the belt of stinging cells at the base of the polyp bod}'. Delafields haematoxyline — Iron
ammonium sulfate. ^^/j.

— 8. Myriothela pJirygia; mutilated specimen from the "Ingolf" st. 125. 2j1.

— 9. Hydractinia cchinata ; spines from the Greenland specimen. ^/^

— 10. specimen from Greenland with extraordinarily large spines. zlz.

— n. Hydractinia carica ; spines from the type specimen. ^/^

— 12. Hydractinia. Sarsii; spines from a specimen from Godthaab harbour, wrongly labelled

"Podocoryne carnea". 6%.

The Ingolf Expedition, V. 6.

Broch: Hydroida. Plate I.

'

"* t\

I a

W

A

/

76

/^

3 a

3h

11

V.

12

Hj. Broch del. et phot.

Ljustr \ I: Lagreliu; & W'estphal, Stockholn

Plate II.

Plate II.

Fig. 13. Corync Loveni; specimen from Bjarkoy, Northern Norway. ^/^

— 14. Corymorpha groenlandica; one of A 11 mans type specimens of Monocanlus groenlandica show-

ing the young blastostyles as mere sacs without any trace of the single gonophores. 3°^.

— 15. Corymorpha groenlandica from the Davis street, wrongly labelled "Amalthcea islandica".

Nat. size.
- 16. Tubular ia pulcher. Gonophore of one of the type specimens of "Auliscus pulcher". 6o/,.

— 17. Merona cornucopia on Cardium sp. from the Faroe-islands. i°/s.

The Ingolf Expedition, V. 6.

/I

7 V

. i -

.

Broch: Hydroida. Plate II.

i

' -T\

15

14

13

16

r

%

17

Hj Broch del. et phot

Ljusir. A. R. Lagrelius & Westphal. Stockholn

THE INGOLF-EXPEDITION

1895 — 1896.

THE LOCALITIES, DEPTHS, AND BOTTOMTEMPERATURES OF THE STATIONS

Station

Nr.

Lat. X.

Long. W.

Depth
in Bottom-

Danish
fathoms

temp.

Station
Xr.

Lat. X.

Long. W.

Depth

in
Danish
fathoms

Bottom-
temp.

Station
Xr.

Lat. X.

Long. W.

Depth

in
Danish
fathoms

Bottom-
temp.

i

2

3
4
5
6

7
8

9
io
II

12
13
14
15
16

17
18

19
20
21
22
23

62 ° 30'
63° 04'

63° 35'
64° 07'
64° 40'
°3° 43'
&3C 13'
630 56'
640 18'
64° 24'

64° 34'
64° 38'
64° 47'
64° 45'
66° 18'

65° 43'
62° 49'
61° 44'
6o° 29'
58° 20'
58° 01'
58° 10'
6o° 43'

8°

21'

9°

22'

io°

24'

n°

12'

12°

09'

14°

34'

15°

41'

24°

40'

27°

00'

28°

50'

3i°

12'

32°

37'

34°

33'

35°

05'

25°

59'

26°

5S'

26°

55'

30°

29'

34°

14'

40°

48

44°

45'

48°

25'

56°

oo'

132

262

272

237

155

90

600

136

295

788
1300
1040

622

176

330
250

745
"35
1566
1695
1330
1845

Only the

Plankton Net

used

7"2

5°3
o°5

2°5

7°o

4°5
6°o
5°S
3°5
i°6

o°3
3°°
4°4
-o°75
6°i

3°4
3°o

2°4

i°5

2°4

i°4

24
25

26

27
28

29
3°
31
32
33
34
35
36
37
38
39
40

4i
42
43
44

63° 06'
63° 3°'
63°5i'
°3° 57'
64° 37'
64° 54'
650 14'
65° 34'
66° 50'
66° 35'
66° 35'
67° 57'
65° 17'
65° 16'
61° 50'
60° 17'
59° I2'
62° 00'
62° 00'

61° 39'
6i°4i'
61° 42'
61° 42'

56° 00'
54° 25'
53° °3'
52° 41'
54° 24'
55° lo-
SS0 42'
54° 31'
54° 28'
55° 54'
56° 38'
55° 3°'
54° 17'
55° 05'
56° 21'

54° 05'
51° 05'
22° 38'
21° 36'
17° 10
io°i7'
10° 11'
9° 36'

1 199

5S2

136

34

109

393

420
68
22
88

3iS
35
55

362

1435
1715
1870

865
845
1245
625
645
545

2"4

o°6

3°8
3°5

0°2

i°Q5
i°6

3°9
o°8

3°6
i°5
i°4
i°3

2°9

3°3

2°0

o°4

o°o5

4°8

45

46
47
48
49
50
51
52
53
54
55
56
57
58

59
60
61
62
63
64
65
66

67

6i°32
61° 32'
61° 32'
6i°32'
62° 07'
620 43'
64° 15'
63° 57'
630 15'
63° oS'

63° 33'
64° oo'

630 37'
64° 25'
65° 00'
65° 091

65° 03'
63° 18'
62° 40'
62° 06'
61° 33'
6i°33'
61° 30'

9° 43'
11° 36'

13° 4o'
15° 11'
15° 07'
15° 07'
14° 22'

i3°32'
15° 07'
150 4o'
15° 02'
ts 09'
13° 02'
12^ 09'
n° 16'
12° 27'
1 3° 06'
19° 12'
19° 05'
19° 00'
19° 00'
20° 43'
22° 30'

643
720

95°

1 150

1 1 20

1020

68

420

795
691
3i6
68
35°
211

3io
124

55

72

800

1041

1089

1 128

975

4°i7

2°40

3°23
3°i7

2°9I

3°i3
7°32
7°87
3°o8

3°9

5°9

7°57

3°4

o°8

o°l

o°9

o°4

7°92

4°o

3°i
3°o

3°3
3°o

Station

Nr.

Lat. N.

Long. W.

Depth

in
Danish
fathoms

Bottom-
temp.

Station

Nr.

Lat. N.

Long.W.

Depth

in
Danish
fathoms

Bottom-
temp.

Station

Nr.

Lat. N.

Long.W.

Depth

in
Danish
fathoms

Bottom-
temp.

68

620 06'

22° 30'

S43

3°4

92

64° 44'

32° 52'

976

i°4

11S

68° 27'

8° 20'

1060

- i°o

69

620 40'

22° 17'

589

3°9

93

640 24'

35° 14'

767

x°46

rig

67° 53'

10° 19'

IOIO

— i°o

70

63° 09'

22° 05'

J 34

7°o

94

64° 56'

36° 19'

204

4° 1

120

67° 29'

n°32'

885

— i°o

7i

63° 46'

22° 03'

46

65° 31'

300 45'

213

121

66° 59'

13° 11'

529

— o°7

72

63°I2'

23° °4'

197

6°7

95

65° 14'

300 39

752

2°I

122

66° 42'

14° 44'

"5

i°8

73

62° 58'

230 28'

4S6

5°5

96

65° 24'

29° 00'

735

I°2

123

66° 52'

15° 40'

145

20O

74

620 17'

240 36'

695

4°2

97

650 28'

27° 39'

45o

5°5

124

67° 40'

15° 40'

495

-o°6

61° 57'

250 35'

761

98

65° 38'

26° 27'

138

5°9

125

68° 08'

l60O2'

729

— o°8

61° 28'

250 06'

S29

99

66° 13'

25° 53'

187

6°i

126

67° 19'

15° 52'

293

-o°5

75

6i°28'

260 25'

780

4°3

100

66° 23'

14° 02'

59

o°4

127

66° 33'

20° 05'

44

5°6

76

6o° 50'

260 50'

806

4° 1

101

66° 23'

12° 05'

537

— o°7

128

66° 50'

20° 02'

194

o°6

77

60° 10'

26° 59'

95i

3°o

102

66° 23'

io° 26'

75o

-o°9

129

66° 35'

23° 47'

117

6°5

78

6o° 37'

27°52'

799

4°5

103

66° 23'

8° 52'

579

-o°6

130

63° 00'

20° 40'

338

6°55

79

60° 52'

280 58'

653

4°4

104

66° 23'

7° 25'

957

— i°i

131

63° 00'

19° 09'

698

4°7

80

6l°02'

290 32'

935

4°o

105

65° 34'

7° 31'

762

— o°8

132

63° oo'

17° 04'

747

4°6

81

61° 44'

270 00'

485

6° 1

106

65° 34'

8° 54'

447

-oc6

133

63° 14'

11° 24'

230

2°2

82

61 ° 55'

270 28'

824

4° 1

65° 29'

8° 40'

466

134

62° 34'

io° 26'

299

4° 1

83

62° 25'

280 30'

912

3°5

107

65° 33'

io° 28'

492

- o°3

135

62° 48'

9°48'

270

o°4

620 36'

26°Ol'

472

108

65° 30'

12° 00'

97

i°i

136

63° 01'

9° 11'

256

4°8

620 36'

250 30'

401

109

65° 29'

13° 25'

38

i°5

137

630 14'

8° 31'

297

-o°6

84

620 58'

250 24'

633

4°8

no

66° 44'

ii° 33'

781

— o°8

138

63° 26'

7° 56'

47i

-o°6

85

63° 21'

250 21'

170

in

67° 14'

8° 48'

860

— o°9

'39

63° 36'

7° 30'

702

-o°6

S6

65° 03'6

230 47'6

76

112

67° 57'

6° 44'

1267

— i°i

140

63° 29'

6° 57'

780

-o°9

87

65° 02'3

230 56'-.

no

113

69° 3i'

7° 06'

1309

— i°o

141

63° 22'

6° 58'

679

-o°6

88

64° 58'

24° 25'

76

6°9

114

70° 36'

7° 29'

773

— i°o

142

63° 07'

7° 05'

5S7

-o°6

89

64° 45'

270 20'

310

8°4

115

70° 50'

8° 29'

86

o°i

143

62° 58'

7° 09'

3S8

-o°4

90

64° 45'

290 06'

56S

4°4

116

70° 05'

8° 26'

37i

-o°4

144

62° 49'

7° 12'

276

i°6

91

64° 44'

3i°oo'

1236

3°i

117

69° 13'

8°23'

1003

— l°o

■■:■>»<:••

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4

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THE DANISH INGOLF-EXPEDITION.

HITHERTO PUBLISHED:

1899. Vol. I, Part I. 1. Report of the Voyage by C.F. Wandcl (1 plate) ")

2. Hydrography by Martin Knudsen (34 plates) )

1900. — Part II. 3. The deposits of the sea-bottom by O. B. Bocggild

(7 charts)

4. Current-bottles by C. F. Wandel (1 plate)

1899. Vol. II, Part I. The ichthyologieal results by Chr. Lutken (4 plates) . . .

1899. — Part II. On the Appendices genitales (Claspers) in the Greeulaud-

Shark, Somniosus microcephalus (Bl. Schn.), and other Sela-
chians by Hector F. E.Jungersen (6 plates)

1900. Part III. Nudibranchiate Gasteropoda by R.Bergh (5 plates)...
1904. — Part IV. The North-European and Greenland Lycodinse by

Adolf : ' Sever in Jensen (10 plates)

1912. Part V. Lamellibranchiata, Part I, by Ad. S. Jensen. (4 plates

and 5 figures in the text)

1899. Vol. Ill, Part I. Pycnogonidse by Fr. Meinert (5 plates)

1908. Part II. Crustacea Malacostraca, I: Decapoda, Euphausiacea,

Mysidaeea by H. J. Hansen (5 plates)

1913. — Part III. Crustacea Malacostraca, II: Tanaidacea by H.J. Hansen

(12 plates; ■

1915. Part IV. Copepoda I. Calanoida. Amphascandria by Carl With

(8 plates, 422 textfigures)

1916. — Part V. Crustacea Malacostraca, III: Isopoda by H.J.Hansen

(16 plates)

1903. Vol. IV, Part I. Echinoidea, Part I, by 77/. Mortcnsen (21 plates)

1907. — Part II. Echinoidea, Part II, by TJi. Mortcnsen (19 plates)

1914. — Part III. Chaetognaths by R. von Rittcr-Zaliony

1904. Vol. V, Part I. Peunatulida by Hector F. E.Jungersen (3 plates)

191 2. — Part II. Ctenophora by T/i. Mortcnsen (10 plates and 15 figures

in the text)

1912. Part III. Ceriantharia by Oskar Carlgren (5 plates and 16 figures

in the text)

1913. — Part IV. Zoautharia by Oskar Carlgren (7 plates and 6 figures

in the text)

1914. — Part V. Stylasteridae by Hjalmar BrocJi (5 plates and 7 figures

in the text)

1916. Part VI. Hydroida by Hjalmar Brocli (2 plates and 20 figures

in the text)

1902. Vol. VI, Part I. Porifera (Part 1), Homorrhaphidse and Heterorrhaphidse

by Will. Lundbeck (19 plates)

1905. Part II. Porifera (Part 2), Desmacidonidse (Pars) by Will. Lundbeck

(20 plates)

1901. Part III. Porifera (Part 3), Desmacidonidae (Pars) by Will. Lundbeck

(11 plates)

Kr. 25,00
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