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THE

VOYAGE OF H.M.S. CHALLENGER.

ZOOLOG Y-VOL. VI.

REPORT

Or

a..

3f>C

ON THE

SCIENTIFIC RESULTS

OF THK

VOYAGE OF H.M.S. CHALLENGER

DURING THE YEARS 1 873-76

UNDER THE COMMAND OF

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

AND

Captain FRANK TOURLE THOMSON, R.N.

PREPARED UNDER THE SUPERINTENDENCE OF

THE LATE

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

REGIUS PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF EDINBURGH
DIRECTOR OF THE CIVILIAN SCIENTIFIC STAFF ON BOARD

AND NOW OF

JOHN MURRAY, F.R.S.E.

ONE OF THE NATURALISTS OF THE EXPEDITION

Zoology — Vol. VI.

woods

MASS.

IPublfsbeo bp corner of IDer ittajestp's 0otoernment

PRINTED FOR HER MAJESTY'S STATIONERY OFFICE

AND SOLD BY

LONDON :— LONGMANS & CO.; JOHN MURRAY; MACMILLAN & CO.; SIMPKIN, MARSHALL, & CO.
TRUBNER & CO.; E. STANFORD; J. D. POTTER; AND KEGAN PAUL, TRENCH, & CO.
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1882

Price Forty-two Shillings.

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CONTENTS.

I. — Report on the Actiniaria dredged by H.M.S. Challenger, during the years

1873-1876.

By Professor Richard Hertwig.

(Received February 1, 1882.)

II. — Report on the Tonicata collected during the Voyage of H.M.S. Challenger,
during the years 1873-76. — Ascidle Simplices.

By William A. Herdman, D.Sc, F.L.S., F.R.S.E., Professor of Natural History

in University College, Liverpool.

{Received November 1, 1882.)

79079

EDITORIAL NOTE.

The first Memoir in the present volume is a Report on the Actiniaria of the
Expedition, by Professor Richard Hertwig, of Koenigsberg.

This Report is not complete, in so far as it does not embrace the whole of
the Challenger collection. A considerable number of specimens did not reach
Professor Hertwig till some time after he had completed the examination of
the collection originally sent to him, indeed, not till the present paper was in
type. Professor Hertwig has kindly undertaken to prepare a short supple-
mentary Report on the additional specimens here referred to.

The Memoir has been translated from the German by Miss Nellie
Maclagan.

The second Memoir is the first part of a Report on the Tunicata of the
Expedition, by Professor W. A. Herdman, of University College, Liverpool.

As Professor Herdman had completed the examination and description of
the Ascidise Simplices, he consented to the separate publication of this
portion of his Report.

The second part of his Report, which will consist of a description of the
Ascidias Composites and the Pelagic Tunicates, will, it is hoped, be ready for
publication within a year from the present time.

The above Reports form respectively Parts XV. and XVII. of the Zoolo-
gical Series. Part XVI. was published in Vol. V.. Zoology.

John Murray.

THE

VOYAGE OF H.M.S. CHALLENGER,

ZOOLOGY.

REPORT on the Actiniaria dredged by H.M.S. Challenger during the
years 1873-187G. By Prof. Richard Hertwig.

INTRODUCTION.

In investigating the Anthozoa the majority of earlier naturalists were content to give
the most exhaustive description possible of the parts which are externally visible in the
living animal, and of the skeleton where such a structure existed ; on the other hand,
they only went slightly into more exact anatomical details, as the observation of
these presented great difficulties. The majority of the Anthozoa are not sufficiently
transparent to allow of the recognition of the form and arrangement of the organs in the
living animal, whilst after death they are so contracted that all the parts become mis-
placed in many ways and pressed one against the other, and can only be demonstrated,
with great care, by means of knives and scissors. Up to the present time the systematic
survey and characters of the orders, families, and genera are founded upon external
characteristics which are of less morphological importance.

In this way many errors arose, which have only become intelligible from the
work of the last decades. Following the steps of Agassiz (Contrib. to the Nat. Hist.
of the United States, vol. iii.), Moseley (Phil. Trans., vol. clxvi. pt, 1, p. 91, 1876; vol.
clxviii. pt. 2, p. 425, 1878) has shown in the most convincing fashion that many hydroid
polyps which form skeletons have been long placed among the reef-forming corals, and
that, moreover, in consequence of the skeletal formation alone having been taken into
consideration, many Octocorallia have been disconnected from their natural systematic
place, and united to forms entirely remote. It cannot by any means, be asserted that

^"(ZOOL. CHALL. EXP.— PART XV. 1882.) P 1

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

recent discoveries have led to the exhaustion of the more comprehensive reforms of the
system of Corallia, as up to the present time we only know the structure of the soft parts
of tin' I mily, especially of the septa, from a comparatively small number of species, and
our knowledge, even of such forms as have been most thoroughly investigated, is far
from satisfactory.

This also holds good for the soft-membraned Anthozoa, the Actiniaria or Malaco-
dermata. In this section the structure and arrangement of the septa are of the highest
importance for the proper comprehension of the structure ; they will probably require to
be taken pre-eminently into consideration in the classification, not only of the Actinia? but
also of the other Hexacorallia. But how little do we know on this point. In a recently
published work (Studien zur Bliittertheorie, Heft i., die Actinien, Jenaische Zeitschrift, Bd.
xiii. p. 457, 1879) my brother and I have tried to show that all the important charac-
teristics have hitherto been properly estimated only in a treatise by Schneider and
Rotteken (Ann. Mag. Nat. Hist., ser. iv., vol. vii. p. 437), and that, on the other
hand, both v. Heider (Sitzungsber. d. Kaiserl. Acad. z. Wien, Math. Nat. Classe, Bd. lxxv.,
Abth. 1, p. 367, 1877), in his otherwise very elaborate anatomy of Sagartia troglodytes,
and Jourdan (Annales d. Sciences Nat., Zool., ser. vi., t. x., No. 1, 1880), in his treatise
on the Actiniae of Marseilles, remain far behind the two first-named naturalists. As,
however, we have only a short report in a preliminary publication on the researches of
Schneider and Rotteken, which extend over a large number of species, it is impossible
to make any systematic use of their material, and therefore the number of more detailed
anatomical studies of Actinia?, which, taken from different species, would enable us to
form an exhaustive plan of the variations of the type common to all, is still incomplete.
These anatomical studies we must have before we can deem it possible to settle an
accurate point of view from which to determine the relations of the Actinia? both to each
other and to the other Anthozoa.

Since it appeared to me a grateful task to make a beginning myself in the direc-
tion just mentioned, I accepted with pleasure the offer made to me to undertake the
working out of the Actinia? collected by the Challenger Expedition. I wish at the same
time to express my most hearty thanks to the late director of the Challenger Commission,
Sir Wyville Thomson, and his first assistant and successor, Mr. John Murray, for the
great liberality with which they placed the rich material collected at my free disposal.

Before going into a description of the separate species, I think it advisable to
determine in a few words the requisites, which, according to my view, ought to be fulfilled
by the anatomical description of an Actinia if this is to be of any systematic value. I
>>liall therefore preface the description by a sketch of the structure of this animal, in which
I shall lay stress upon the points which are most subject to variation, and to which the
special attention of the describer must be directed. Such an attempt is also to be
recommended for the further reason that in this way the reader will at the same time

REPORT ON THE ACTIKTARIA. 3

become familiar with the nomenclature, which, taken partly from earlier authors, and
founded to some extent upon my own observations, will be adopted in the following
pages. I shall also be able to interweave short remarks upon the most serviceable
methods of investigation.

The body of the Actinia is shaped like a hollow cylinder, which is usually very long
in proportion to its breadth, but which can also be shortened to a discoid form under
certain circumstances. It is limited by two terminal surfaces, the "oral disk" or
" peristome," and the " pedal disk " or " base," whilst the body wall corresponding to the
outer surface of the cylinder is termed the " mural layer," or shortly, the " wall "; the wall
is usually separated from the pedal disk, always from the oral disk, by a sharp margin,
the twro surfaces here meeting at a right or even at an acute angle ; the wall occasionally
passes gradually inwards into the base, in such a way that we cannot speak of a separate
pedal disk.

Towards its periphery the oral disk bears the tentacles, which are simply hollow
evaeinations of the disk. Besides these " marginal " tentacles there are also " circumoral"
tentacles, which are united in a corona round the oral opening, and " intermediate "
tentacles, which occupy a position between the oral opening and the margin of the disk.
As the first are always present, and the last two only exceptionally, those may be termed
the " primary" or " principal " tentacles, these the " secondary " or " accessory " tentacles.

The oral opening, placed in the middle of the oral disk, leads into a tube which
hangs down a little -way into the hollow space of the body, and in the older descrip-
tions was held to be a stomach, a name which we may now suitably abandon and replace
by the term " oesophagus." This ends before it reaches the pedal disk in a free margin,
and communicates by a wide opening, the " gastric orifice " or " cardia," with the large
hollow space which occupies the inside of every Actinia, and is developed from the
primitive intestine of the gastrula, whilst morphologically and physiologically it
replaces the intestine and body cavity (enterocoele) of the bilaterals. Leuckart's term
" ccelenteron," or " ccelenteric space," is therefore specially appropriate to the Actiniae.

The oesophagus hanging down in the ccelenteron is fastened to its place by the
numerous septa (sarcosepta, Hseckel) which spring from the oral disk, wall, and pedal
disk, and are attached superiorly to the oesophagus, whilst they end in a free margin
below\ They therefore divide the peripheral part of the ccelenteron into simple radial
chambers, which are closed where they surround the oesophagus and where they pass into
the hollow spaces of the tentacles, but which open downwards between the free margins of
the septa into the "central stomach," i.e., into that part of the ccelenteron which lies
under the oesophagus and is no longer divided into chambers by the septa.

All the above-mentioned walls and septa of the body of the Actinia are lamella? of
no great thickness, and in many species the wall only is a tough sheath. The
firmness of the lamella? depends upon their fundamental substance of connective tissue,

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

which, according to the degree of their histological differentiation, may be homogeneous
and nut enclosing cells, homogeneous and enclosing cells, or, finally, fibrous and containing
cells. The framework of connective tissue gives us an accurate figure of the corporeal
form of the Actinia even when the epithelial parts have been removed by maceration ;
from the standpoint of the " Bliittertheorie," it must be termed the middle layer of the
body or mesoderm.

All the lamellae of connective tissue are covered on either side by a single layer of
epithelial cells, which are distinguished by extraordinary length and thinness, and may,
moreover, be placed in different categories according to their different functions. The
most usual form is seen in the " supporting cells," in which, despite their fineness in an
isolated condition, we can recognise a distinct, triangular, basal expansion. The most
common after these are the " urticating cells " and " gland cells." In the former the body
is expanded by the presence of the thread, in the latter it is distended by glandular
secretion stored up in it. The form of the nematocysts, and the nature of the thread
contained in them is not the same everywhere, and may, perhaps, some day become of
systematic importance. The glandular secretion is also of different kinds ; it sometimes
fills the body of the cell, as a homogeneous, glassy mass, sometimes it is deposited as
a mass of closely compacted granules, greedily absorbing colouring matter. The fourth
form of cells is that of the " sense cells," which have the same fine, filamentous nature as
the supporting cells, from which, however, they can be distinguished in an isolated
condition by their central end giving off two or more fine nerve threads, which have a
tendency to become varicose.

With the exception of the glandular cells, all the cells bear appendages at the
peripheral end ; the sense cells, and probably also the urticating cells, have fine, long,
tactile bristles, of which each cell usually possesses only one ; the supporting cells bear a
bunch of cilia, or a simple flagellum. Ciliated cells and flagellate cells may be present
in the same animal, e.g., in most Actinias the ectodermal epithelium is made up of the
former, the endodermal of the latter, whilst in Cerianihus we find only flagellate cells.
We have as yet no satisfactory knowledge of the manner in which the two forms of
cells are distributed among the Actinia?.

The epithelial coverings are derived immediately from the two primitive layers of cells
of the gastrula larva, the endoblast and the ectoblast, and in the developed animal are
therefore to be distinguished as separate body layers, as endoderm and ectoderm, even
when they hardly vary in their histological character. The ectoderm covers the outer
surface of the body and the inside of the oesophagus ; the endoderm covers everything
else, i.e., the inner wall of the whole ccelenteron, and the inner spaces of the tentacles.
The supporting lamellae of the wall, of the oesophagus, &c, are therefore covered with
ectoderm on one side and with endoderm on the other ; the septa only form an
exception, as they bear endodermal epithelium on both sides.

REPORT ON THE ACTINIARIA. 5

Among the histological elements of the Actinia we must finally mention the
muscle cells, nerve cells, and reproductive cells ; we shall merely discuss the two former
here from a general point of view. The muscles originate either from the ectoderm
or the endoderm, and usually continue to belong to both these epithelial layers. They
consist of flat, fusiform, muscular fibrillae, to one side of which the cell from which they
were originally produced is attached. This latter is usually at the same time an epithelial
cell, and with the fibre belonging to it represents an epithelio-muscular cell, or it is a
cell lying in the deeper layers of the epithelium, and no longer extending as far as the
surface, an epithelial cell, whose peripheral end has undergone retrograde formation, or
a subepithelial muscle cell.

The principle of arrangement of the fibrillar is the same in both cases ; they are placed
on the borders of the epithelium and the mesodermal connective substance, and form
a thickly apposed simple layer, a muscular lamella. The muscles are not strengthened by
the deposition of new layers of fibres, but by the " pleating " of the single-layered lamellae.
The underlying connective substance also comes into play, supporting all the folds of the
muscular lamella by fine leaf-like processes (PI. V. figs. 7-10 ; PI. VI. figs. 4, 6).

The pleating of the epithelial, or subepithelial muscular lamella, becomes in many
cases the starting-point for the development of a third form of the muscular fibres, the
" mesodermal " fibres. When the surfaces of the supporting substance, which borders a
muscular fold laterally, approach so that here and there they touch and become fused,
the connection of the lower part of the pleating with the epithelium is dissolved, and
it becomes completely enclosed in the mesoderm (PI. VII. fig. 8). In this way are found
in transverse sections, circular figures, whose periphery is occupied by the divided
fibrillar, whilst the centre contains the muscular corpuscles belonging to it. The trans-
formation of the epithelial muscular elements into mesodermal can go so far that
considerable masses of muscles he in the mesoderm (PL IV. figs. 5-8 ; PL VI. figs. 1-3, 5).

In describing the muscles of the Actiniae we must, therefore, be careful to note
whether they are ectodermal, endodermal, or mesodermal, whether they extend simply
in a smooth lamella, or are disposed in folds ; as we shall see, they present in this way
many characteristics of systematic value. This cannot be said of the nervous system, which
I only go into here for the sake of completing my description. Nerve fibres and ganglion
cells are found, in thoroughly examined Actinia3, in nearly all the epithelial laminae,
where they form a layer between the bases of the epithelial cells. The layer is extremely
thin in the ectoderm of the pedal disk, and usually also in that of the wall, whilst
it is very strong in the ectoderm of the tentacles, of the oral disk and of the oesophagus.
Nervous elements are usually less frequent in the endoderm, and only produce visible
cords in the mesenteric filaments and acontia. We may lay down as a rule, that, where
muscular filaments are present, the layer of nervous filaments lies over the former,
and is most easily found in that place.

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

I have us yet only given a general survey of the anatomical and histological parts
composing the organisation of the Actiniaria ; it now remains for me to discuss the
differentiations shown by the histological elements in their nature, distribution, and
arrangements in the various parts of the body, and. to show how we may thereby acquire
a knowledge of the more accurate characteristics of these parts.

The pedal disk does not present much worthy of notice ; it has a slightly developed
endodermal muscular layer, always running circularly, which is often even wanting ; in the
centre there are sometimes, but rarely, one or more small openings, through which the
water can find entrance and exit ; as yet, however, such openings have only been
observed where the pedal disk and wall pass continuously the one into the other, which
condition is usually described as absence of the pedal disk. Eadial furrows may also
run on the outside of the pedal disk, and usually correspond to the insertions of the
septa on the inside (PL IV. fig. 2 ; PL IX. fig. 5). The wall is much more complicated
both on its endodermal and its ectodermal sides ; on the former there often lies a layer
of circular muscular fibres, which appears everywhere as a flat or slightly folded lamella,
but is also often more strongly developed in certain places, and forms a special muscular
cord acting as a sphincter. The sphincter or circular muscle usually lies immediately
below the upper margin of the wall, which it draws together like a bag over the oral
disk and the tentacles if the latter require shelter from any threatened danger. A
second sphincter, lying further down, may also be added to the upper sphincter.

The nature of the sphincters varies great ly. "We talk of a " diffuse " sjihincter
when it merely arises from repeated pleatings of the muscular lamella ; because in that
case it is not sharply defined at the upper and lower margins (PL V. fig. 8), it does not
strike the eye in looking at the surface, and is shown in transverse section only by the
local thickening of the wall in whose substance it is completely embedded. A " circum-
scribed " sphincter is formed when the pleated muscular mass projects above the inner
surface of the wall, with which it is connected only by a narrow band, so that an annular
swelling arises which is easily observed both in looking at the surface and in transverse
section (PL VII. figs. 2, 4). Finally, in the " mesodermal " sphincter, the muscles
have left their original position in the epithelium, and are completely hidden in the
supporting substance, which consequently increases doubly or trebly in thickness (PL
VII. fig. 7 ; PL VI. figs. 1-3).

The complete absence of the sphincter is comparatively rare. I have only observed it
in a few species (e.g., in the representatives of the genus CorcUUmorphus), almost invari-
ably animals which are not capable of contracting the upper margin of the wall over the
oral disk. This is, however, also the case in animals with a weak sphincter, such as the
Antheadse. On the other hand, the existence of a strong circular muscle can often be
inferred with tolerable certainty from a high degree of contraction. The capacity for
concealing the oral disk plays an important part in the systematic division of the

REPORT ON THE ACTINIARTA. 7

Actiniaria ; this is generally most inappropriately expressed by the term " retractile
tentacles." It would be decidedly more rational to make the anatomical reason, and not
the physiological appearance, of systematic value. We shall therefore talk of Actiniaria
without sphincter, and of Actiniaria with weak and with strong sphincter, and further
distinguish in the latter case whether the muscle is endodermal or mesodermal.

The systematic value of the circular muscle does not end here, a.s it furnishes a
character not to be undervalued, for determining the species. The extraordinary variations
of the circular muscle are shown by a glance at Plates VI. and VII. ; in the endodermal
forms the shape and mode of branching of the muscular folds vary, in the mesodermal
the shape and grouping of the bundles formed by the fibres, and also their position
in the more superficial or deeper layers of the wall. I lay stress upon this point, as
the circular muscle can be examined in the preserved animals even when their state of
preservation is not very favourable, and because, moreover, a small piece of the wall,
which can be cut away without essential damage to the whole animal, is sufficient for
such an investigation.

Muscles, especially longitudinal muscles, are rarely present on the ectodermal side of
the wall, whilst, on the other hand, it is not unusual to find " marginal spherules " and
different forms of papilla?. The marginal spherules (" bourses marginales," Hollard, Ann.
d. Sci. Nat., Zool., ser .iii., t. xv. p. 257) follow immediately outside the tentacles, and
are evaginations of the mural membrane, just as the tentacles are evaginations of the
oral disk. All the layers of the body participate in the evagination, though the ectoderm
alone undergoes modification of its structure, being extraordinarily rich in nematocysts.

The papillae, to which such importance was attached in earlier investigations of the
Actinia?, are formations of very subordinate value ; they are caused by mere local growth
of the supporting plate, and are not distinguished by a single special property of the
covering epithelium (PI. VIII. fig. 4). Hence the observer often found himself on the
horns of a dilemma when he had to decide whether papilla? were present or not. A
smooth surface may become papillose in consecpaence of contraction, and, on the other hand,
small papilla? may disappear when, as often happens, the Actinia becomes distended
like a drum. It wTould, therefore, be better in future only to make the papillose or
smooth nature of the membrane of value in distinguishing species, or at most of genera,
and to disregard it in the formation of larger divisions.

The comportment of the epidermis appears to me much more important. The majority
of the Actinia? have a smooth surface, on which particles of mucus become secreted
when the animal is irritated ; histological investigation then shows an active ciliated
epithelium composed of extremely long, thin cylindrical cells. Besides this, two varying
modifications of the integument have already been specially observed. In the one case,
in Cerianthus, the epithelium is covered externally by a tough membrane, consisting
of mucus., nematocysts, and scattered foreign bodies, which can be stripped off, but which

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

is rapidly regenerated, and in which the animal is concealed as in a sheath ; in the other
case there is a membrane present which cannot be stripped off, and which gives the
surface a rough, bark-like appearance ; this has received the very unsuitable name of
" epidermis." In fact, we have to deal with a cuticular formation. In the most simple
cases, where the epithelium does not bear cilia, it is covered loosely by a thin, irregular
fibrous membrane, outside which is a layer of mucus, traversed by all sorts of foreign
bodies (PI. VIII. figs. 1 and 6). This cuticular secretion rarely becomes a broad, stratified
mass resting firmly on the epithelium, and recalling completely the cuticula of the worms
(PL XII. figs. 1 and 2).

The wall can also be traversed like the pedal disk by furrows, which run in a
longitudinal direction from the base to the border of the oral disk, and likewise
correspond to the septa.

The possible presence of " cinclides " must finally be taken into consideration ; this is
the name applied by Gosse (Actinologia Britannica, 1860) to openings in the wall through
which water and the acontia. which we have still to describe, can be ejected from the
inside of the body. Such cinclides can be observed in Calliactis parasitica, even in
spirit specimens, where they are arranged in a circle at a little distance from the pedal
disk. In other cases, on the contrary, we see that acontia issue from the interior of the
living animal through the wall, but it is impossible to find performed openings, even if
we take a protruded acontium as guide. Whether the opening is difficult to find out, or
whether it is not performed, but arises afresh each time by rupture, as v. Heider assumes,
must still be regarded as an open question. That is a point which essentially lowers the
systematic value of the cinclides. Gosse has certainly made light of the question, and
assumed the presence of cinclides wherever he noticed the passage of the acontia, even
though he did not find any openings. Such a method of treatment, however, can
be properly carried out only in the living animal, as spirit material leaves the question
undecided.

The oral disk is furnished on both sides with muscular fibres, running radially on
the ectodermal side, circularly on the endodermal ; the latter are connected immediately .
with the muscular fibres of the wall, with which they form a continuous layer. Whilst
the endodermal muscular fibres possess no further interest, and comport themselves, so to
speak, in the same manner throughout, the development of the ectodermal muscular fibres
is subject to numerous variations, which, like the nature of the sphincter, can be turned
to good account for more accurate determination of the species. In all cases we must
distinguish whether the muscular fibres maintain their original place in the epithelium,
or whether they have passed wholly or partially into the mesoderm. AVe must, moreover,
pay attention in the first instance to whether the muscular lamella is smooth or pleated,
and in the second instance to the form and arrangement presented by the mesodermal
bundles of fibres.

REPOKT ON THE ACTINIARIA. 9

The same questions recur in the tentacles, which are merely evaginations of tin-
oral disk. Here the endodermal circular muscular fibres are always uniform, whilst the
ectodermal longitudinal cords vary. Moreover, there are usually, if not always, open-
ings present in the tentacles through which water is ejected when the animal becomes
contracted; they occupy the point of the tentacles, and are easily observed in the
living animal. In order to find them out in the spirit material I fastened a tentacle,
which had been cut off, to a tube and inflated it with air underwater; if an opening
were present the air bubbled out through it.

According to their shape the tentacles are distinguished as "knobbed," "club-shaped,"
"branched," "conical," &c, terms which do not recpiire further explanation. Their
mode of arrangement, of which I shall speak in connection with the septa, is also of
importance. On the other hand, their length and shortness is a characteristic which is
not capable of exact definition, and cannot be determined with any certainty in the
spirit specimens, as it is impossible to judge to what extent the length has been
influenced by a greater or lesser degree of contraction. This characteristic cannot, how-
ever, be dispensed with for systematic purposes.

Whether the tentacles in the Actinias may be entirely wanting, without being
morphologically replaced in some way or another, seems to me questionable, as no such
case is known up to the present time. The tentacles may, however, undergo a peculiar
retrograde metamorphosis, progressing so far that only the terminal opening is left in the
form of a fissure, which is enclosed by thickened lips, and, lying in the periphery of the
oral disk, shows the spot where we might have expected to find the tentacle. I have
observed different stages of this retrograde formation in species of Actinias coming from
great depths. We see the beginning of it in Polysiphonia tuberosa (PI. II. figs. 7, 9),
also Sicyonis crassa (PI. IV. fig. 4), and the advanced stages in Pohjopis striata
(PI. II. fig. If), and Polystomidium patens (PI. V. fig. 6).

The oral opening is only exceptionally round ; it has usually the form of a fissure
whose longitudinal diameter lies in the same direction in all Anthozoa. It is therefore of
the greatest importance for distinguishing the axes which may be drawn through the
body of the Actiniae. If the Actiniae were animals possessing perfect radial symmetry,
then the longitudinal axis, determined by its passing through the oral and aboral poles,
would be the only constant one, and all radial axes lying perpendicular to the
longitudinal would then be perfectly equivalent to one another. By the constant
form of the oral opening, the radially symmetrical fundamental form becomes more
definite, and is at least transformed into the biradially symmetrical form. In all cases,
two of the radial axes strike us as specially distinguishable, the sagittal axis running
in the direction of the oral fissure, and the transverse axis perpendicular to it. We can
even exceptionally recognise a dorsal and a ventral side at the ends of the sagittal axis,
and a right and a left side at the ends of the transverse axis, and hence the

(ZOOL. CHALL. EXP. PAUT XV. 1882.) 1' -'

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

biradially symmetrical fundamental form is transformed into the bilaterally symmetrical.
I lay great stress upon this apparently unimportant consideration of the form of the
mouth, as it is the expression of a fundamental character in the architecture of the
body of the Actinia, which is, moreover, the standard for the configuration of the
oesophagus and the position of the septa.

The oesophagus is a sac, flattened in the transverse direction, and open below and
above ; it is furnished with circular muscular fibres on its endodermal aspect, whilst it
has exceptionally longitudinal fibres on the ectodermal aspect, the one turned towards the
lumen of the tube. Its walls are solid, and only two instances have been observed in which
they have openings leading into the radial chambers. In the typical Actinias the lower
end of the tube is produced into two long lappets, which fall in the sagittal axis and
consequently under the two corners of the mouth, or, what is the same thing, where the
two wider sides of the tube meet each other. The inner side of the oesophagus is covered
with regularly arranged longitudinal furrows, of which two, corresponding to the angles of
the mouth, are conspicuous by their special breadth and depth. These furrows or grooves
lead from the oral angles to the oesophageal lappets, on which they run up to the end ;
they constitute half canals, which remain open, even when the two wider sides of the
oesophagus are pressed firmly against one another, and then become two canals leading
into the stomach (PL I. figs. 2, 5).

As the oesophageal grooves pass at the one end on to the oesophageal lappets, so they
are bounded at the other end by two lip-kke swellings, which enclose the oral angle :
these are simply strongly-developed papillae, which are also found in varying number on
the oral margin, and' indicate the ends of the longitudinal ridges rising between the
smaller longitudinal furrows of the oesopbagus. The Zoantkeae and Ilyanthidoa form an
exception to what has been said ; the former have only one distinct oesophageal groove,
whilst in the latter there are none worth mentioning. We meet here with differences,
which are correlated with the structure and arrangement of the septa.

The septa are supporting plates formed of connective tissue, which are covered on both
sides by endodermal epithelium, bear muscular fibres on both sides, and thus become
very important organs for the contraction of the body. In those Actiniae, which still preserve
the most primitive structure of the septa, e.g., the genus Corallimorphus, we can dis-
tinguish only two systems of muscles ; the fibres run for the most part longitudinally on
the one side, transversely on the other, forming in both cases a smooth, only slightly
pleated layer. Considered more closely, the former spring from the pedal disk and
the lower parts of the wall, and converge towards the oesophagus and central parts of
the oral disk, whilst the latter arise from the whole length of the wall and are inserted into
the oral disk and the oesophagus. In the majority of Actiniae the longitudinal layer is
differentiated by local, specially rich development of muscular fibres and repeated
pleating into a special more or less sharply-defined muscle, the retractor, which projects

REPORT ON THE ACTINIARTA. 11

to a varying extent above the surface of the septum, and shows many variations in the
details of its constitution; a second specialised but much weaker cord stretches along
the wall, close to the origin of the septum. As the retractor in transverse section is
placed on the septum like a pennon, Schneider and Rotteken have given it the name of
"muscular pennon." On the other hand, the " parietobasilar " muscle is differentiated
from the transverse muscles; it lies in the angle between the pedal disk and wall, into
which it projects with a crescentic margin, like the plica semilunaris in the corner of the
eye. It extends to different distances up the wall and towards the central point of the
pedal disk. It originates from the transverse muscular layer, by a process of pleating which
is beautifully shown in Leiotealia nympkcea. As the muscular fold here still lies loosely on
the septum, we can pass a needle into the pouckdike interspace. Apart from the parieto-
basilar muscle, the transverse muscles are most strongly developed in the upper third of
the body of the Actinia (PL II. fig. 6 ; PL IV. fig. 9 ; PL VII. figs. 5 and 1 2).

As the two surfaces of a septum differ from and are unequal to one another in the
arrangement of the muscles, there are predispositions to a peculiar ai-rangement of the
septa which, with few exceptions, is found in all Actiniae, viz., that the septa are united
in pairs, so that we cannot speak appropriately of single septa but of pairs of septa. The
equivalent sides of the septa of the pair, i.e., the sides in which the muscles run in the
same direction, are turned towards each other. As a rule, it is the sides with the longi-
tudinal muscles, and only in two pairs the sides with the transverse muscles. These two
pairs of septa occupy a perfectly fixed position in the body of the Actinia, and may conse-
quently be used for fixing direction, on wheh account wTe shall name them the " directive
septa. The directive septa correspond to the oesophageal grooves, and are fastened to the
oesophagus from the oral angle downwards to the end of the lappets of the (esophagus.
They constitute the principal reason why such stress should be laid on the form of the
mouth, and they themselves contribute very essentially to a more clear expression of the
biradially symmetrical character of the body of the Actinia.

The history of the development of the septa will help us to understand some further
characteristics of their arrangement. We see from it that the septa of a pair have
generally a common origin, and that only the first six pairs form an exception to this rule.
The most recent researches show that the septa of the first six pairs appear independently
and at different times, and that they become united secondarily in pairs; as they are
placed first, and according to a special principle, it is appropriate to distinguish them as
"principal" septa from the others, the "accessory" septa. In some cases (in Sagartia,
Phellia, c&c.) they are permanently recognisable from the fact that they only are inserted
into the oesophagus; usually, however, this peculiarity is shared by numerous accessory
septa, and they are then merely distinguished by their somewhat larger size. The
difference of size may, however, be almost equalised, which makes the determination of
the principal septa difficult. This is, however, made easier 1 >y the fact that the two pairs

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

of directive septa also belong to the six pairs of principal septa. These are easily found
as they lie at the opposite ends of the oral fissure, and thereby furnish us a fixed
point for the determination of directions. The remaining four pairs of principal septa
are distributed in the space in such a way that each two are found right and left from
the oral fissure at equal distances from one another and from the directive septa. The
six pairs of principal septa form together a regular six-rayed star.

In an Actinia with the first six pairs or the first twelve septa, the space round the
oesophagus is divided into twelve radial chambers, of which six lie inside the pairs and six
between the adjacent pairs. The former are the " intraseptal " spaces or " inner" spaces, the
latter the " interseptal" spaces or " interspaces." Whilst the inner spaces remain unaltered,
the interspaces grow, and the accessory septa develop in them in pairs, and in an arrange-
ment which will not undergo any change. This definite arrangement may be shortly
characterised as follows : — A pair of septa lie in the middle of each interseptal space :
if we term the principal septa septa of the first order, or shortly, " primary septa," these
are the six pairs of septa of the second order, or " secondary " septa. They nearly equal the
primary septa in size, and, except in the Sagartidse, are fused with the oesophagus ; they
divide the interseptal spaces into three parts: (1) an intraseptal space of the second order,
and (2) two interseptal spaces of the second order. Then follow twelve pairs of septa of
the third order in the interspaces between the primary and secondary septa, twenty-four
pairs of septa of the fourth order in the interseptal spaces so formed, and so on. The
septa usually decrease in size, for whilst the first, which arise from the pedal disk and
from the wall, are inserted into the oral disk and the oesophagus, as far as the lower
margin of the latter, the succeeding pairs gradually extend to a less distance down the
oesophagus, then fad to reach it at all, and finally are attached only to the oral disk at a
distance from its centre. The same process is repeated at the pedal disk. The older septa
project nearly as far as the centre of the pedal disk, the younger only a little way inwards
from the periphery. As the size of the septa undergoes very gradual modification, we
can merely place them in two categories, " imperfect " septa, which do not reach as far as
the oesophagus, and " perfect " septa, which are fastened to the oesophagus. After what
has been already said, it is unnecessary to add that all the pairs of secondary septa have
longitudinal muscles on the faces which are turned towards one another, and transverse
muscles on the faces which are turned away from one another.

Methods of inquiry, differing according to the size of the animal, are to be recommended
in order to recognise the above-mentioned conditions. Small specimens may be examined
in transverse sections taken through the oesophagus, by which we survey the whole ar-
rangement of the septa at a single glance. Care must be taken, however, that the section
actually passes through the oesophagus and not somewhat through the oral disk, which in
contracted animals often reaches deep down into the interior. For example, it appears to
me not improbable that v. Heider gave too high a number of complete septa in Sagartia

REPORT ON THE ACTINIARJA. 13

troglodytes, because he mistook sections through the oral disk for sections through the
oesophagus. To avoid such errors it is only needful to bear in mind that the oral
disk has strong radial ectodermal or mesodermal muscles, whUst the oesophagus is almost
always devoid of muscles on its ectodermal side. Oral disk and oesophagus can be also
easily distinguished by the different character of the epithelium.

There are, however, numerous other difficulties attendant on the interpretation of
transverse sections, as the principles of arrangement are often not visible from the large
number of the septa which are pressed together and displaced by contraction. Such sec-
tions are, therefore, unadvisable in large forms, and especially in those of which we have
only a single specimen at our disposal ; in these cases dissection with knives and scissors is
preferable. For this purpose we find out the oral angle, and open the intraseptal space of
a pair of directive septa by an incision into the oesophagus ; when we have cut through
the base of the septum along the oesophagus, oral disk, wall and pedal disk, we have a
fixed starting-point, and are then able to detach the septa pair by pair, and arrange them
in series one after another. Any one at all versed in the matter will soon know from the
size of the septa, from the distance of the directive septa, and from the way in which
the septa follow one another, when he lights upon the next pair of principal septa : he then
knows that he has examined one-sixth of the body, and does not require to investigate
the remaining five-sixths, as the same formation is repeated in the usual forms of Actinia?.

Another mode of preparation, wdiich takes still less time, consists in detaching the
pedal disk in such a way that the bases of the septa still remain in it. By this means we
can easdy see the arrangement of the septa, but not distinguish, however, how many of
them are complete.

When we have separated and prepared the pairs of septa in the manner described,
we also get a view of the distribution of the tentacles which are evaginations both of
the intraseptal and the interseptal spaces. As a rule, each intraseptal space has only
a single tentacle, while the number borne by the interspaces may be greater. This is by
no means remarkable, as the interseptal spaces are seats of active growth. In those
Actinia), in which there is a continual increase in the number of septa in the interspaces,
there is also a continuous evagination of new tentacles, and as the formation of the latter
precedes that of the former, it may happen that numerous tentacles are already present,
whilst the septa belonging to them are either entirely wanting or their rudiments only
perceptible. In Antholoba, for example, the innumerable tentacles of the umbrella
margin belong chiefly to the interspaces (PL I. fig. 9).

Like the septa the tentacles differ in age, so that we can distinguish tentacles of the
first, second, third order, &c. This often causes distinction in size, which is best
seen in the Corallimorphidae, where the entire arrangement of the septa is reflected
in the size of the tentacles (PL 11. figs. 1 and 3). The six largest tentacles belong
to the primary intraseptal spaces, the next six, which are only a little smaller, to the

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

secondary intraseptal, then follow the twelve tentacles of the tertiary intraseptal spaces
which are visibly smaller, whilst the twenty-four last tentacles communicate with the
interseptal spaces. The difference in the size of the tentacles is, however, rarely so
marked as this, for a partial or complete equalisation in their size usually takes place at an
early period of development.

When there are a lar^e number of tentacles there is no room for them in a single
row, but they are forced to form several rows, of which the inner are the oldest, the
outer the youngest. All the tentacles of the same circle are essentially of the same
size, but a difference in size may arise between different circles, which is showm by
the innermost, and therefore oldest, tentacles being the largest, the outermost and
youngest the smallest. If uniform growth take place in all parts of the body of the
Actinia, the whole of the circles are arranged, as may often be seen, in multiples of six.
For example, twelve tentacles of equal size form the innermost circle, if it be composed of
tentacles of the first and second order ; twenty-four, if those of the third order be added to
the number ; the next circle would then be occupied by the twelve or twenty-four suc-
ceeding tentacles of the sequence. There are often, however, numerous variations, caused
by unequal growth in the different sextants ; for example, the tentacles of the third
order may have advanced into the innermost circle in one sextant, whilst in another
sextant they remain in the next circle. In this way it may happen that the arrangements
of the tentacles and of the septa do not correspond completely, even though they are not
directly contradictory, since the tentacles of a later order are, at all events, not laiger
than those of a preceding order. I only know one exception to this rule, Polysipkonia
tuberosa, to the description of which I refer the reader.

Hitherto I have only spoken of tentacles which are placed on the margin, and
which always remain equivalent to each other even when, changing their position for
want of space, they have retreated on to the oral disk, and become apparently arranged
in several rows. I have already placed these primary tentacles in ojyposition to the
secondary tentacles, which are associated with the primary in the Coralliniorphidaa
(PL II. figs 1 and 3). They form a system in themselves, and are placed half-way
between the peripheral and oral margins of the disk. They correspond only to the
intraseptal spaces, and their size is graduated according to the age of the latter.
The above-mentioned rule undergoes an exception here, as each intraseptal space
communicates with two tentacles, a primary placed on the margin, and a secondary
placed on the disk. The Corallimorpkidse are the only exceptions which I have
observed, for the Cerianthidae, which are usually described as Actiniae with a double
corona of tentacles, cannot be considered here because of the aberrant arrangement of
their septa, which are not united in pairs, thus rendering the distinction between the
intraseptal and interseptal spaces impossible.

The septa bear the reproductive organs, the mesenteric filaments, and in many families

REPORT ON THE ACTINIARIA. 15

the acontia. During maturity the reproductive organs lie in the supporting plate com-
posed of connective tissue. They form follicles of spermatozoa in the male, separate ova
in the female, and both together in hermaphrodite individuals ; the youngest ova lie in
the endodermal epithelium, which therefore represents the germinal layer, but even older
eggs — at least this has been observed in several species — are still connected with the
surface of the epithelium, either by means of a conical cord of protoplasm, or by means
of a bundle of epithelial cells, at whose base a process of the ovum passes transversely
through the supporting lamella.

The mesenteric filaments occupy the free margins of the septa, beginning at the
upper end — at the oesophagus in the complete septa — and finishing tit a little distance from
the lower end. They are formed by the supporting lamella (PI. V. fig. 5) splitting at
the free margin into three lamina?, a middle and two lateral ; the former is covered by
a streak of epithelial cells, principally glandular, the latter bear extremely fine, small
ciliated cells. A visible cord of nervous fibres, which is entirely wanting in the ciliated
streaks, runs along the base of the glandular streak. The character of the filamenl
changes lower down, as the ciliated streaks with their supporting plate of connective
tissue disappear, and the median glandular streak only remains.

The acontia (PL 1. figs. 4 and 5) are long filaments, kidney-shaped in transverse
section, which spring from the septa at a little distance from the lower end of the mesen-
teric filaments, lie coiled in the stomach during a state of rest, and are ejected through
special openings in the wall (cinclides), or through breaches in the wall, or through the
oral opening, when the animal is irritated. Their component parts are : (l) an axial band
of connective tissue, (2) an epithelium, chiefly composed of nematocysts, (3) nerves, and
(4) muscular fibres lying between the basal ends of the epithelial cells (PI. XII. fig. 10).

Finally, there are special openings in the septa which connect the separate divisions of
the gastric space. There are two forms of such septal stomata. In nearly all Actinia?
we find openings which pierce the septa just where the latter touch the margin of the
mouth, and which form together a species of peristomial canal ; the upper part of these
openings is limited by the membrane of the oral disk, the remainder by the septa, so
that they are shut off from direct contact with the oesophagus. More rarely there are
other septal stomata, which lie close to the wall, about the junction of the first and
second thirds of the body (PL VII. fig. 12).

I have hitherto described the anatomical conditions of the septa, as they may be
observed in the hexamerous Actiniae, and probably in all hexamerous corals. It would,
however, be very erroneous to assume that what has been said applies to all forms
hitherto included among the Hexacorallia ; we find, in fact, sundry variations, which I
shall place under five different categories, though I do not presume to say that these
exhaust all the variations presented in nature.

Among the first group I place those Actinia? in which there are two pairs of directive

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

septa, in which the remaining septa are grouped in pairs, but in which six is not the
fundamental number for the arrangement of the septa, e.g., Sicyonis crassa with sixty-
four pairs of septa, and Polyopis striata with sixteen pairs. The two directive septa
correspond to two distinct oesophageal grooves.

In the second group we find two pairs of directive septa, the single septa are con-
structed precisely as in the true Actinias, but, with the exception of the directive septa,
are not united in pairs. I name Edwardsia as a type of this group.

In the third division, to which only a single species of those examined by me,
Seytojihonts striatus, belongs, the variation from the typical condition runs in the
opposite direction. The paired arrangement of the septa is preserved, but one pair of
directive septa is wanting (PI. XIII. fig. 3).

In the fourth division we can clearly recognise a single oesophageal groove on the
oesophagus ; the septa inserted at the bottom of the groove may also be defined
as directive septa, but it is not possible to point out on them the muscular arrangement
found elsewhere. They agree, however, with the other septa, in so far as they have a
thin layer of transverse muscular fibres on both sides. This is the case in Cerianthus.
The fifth division is formed by the Zoantkidas, in which the septa are paired, but partially
in a rudimentary condition.

The plan which I have drawn up here, partly from the observations of others, but prin-
cipally from my own earlier and later investigations, of the structure of the Actinias, allows
me to make a few criticisms on the more important systems of Actinias already published.
Ehrenberg in his system of the Actinias, has made use first and foremost of the presence
or absence of the sucking papillae, then of the openings in the mural membrane, and, finally,
of the form, length, and arrangement of the tentacles. The sucking papillae recur in
Gosse's system, though they are made of subordinate importance ; they are described by
him as hollow papillae, furnished with a muscular apparatus, by which a vacuum is
formed. I have entirely omitted the sucking papillae in the general description of the
anatomy of the Actinias, as I have never observed them, even in forms which were
capable of incrusting themselves with foreign bodies. I am the more justified in doubting
their existence, as Gosse has given no proofs verifying his assertions. Jourdan has lately
described something like sucking papillae in Bunodes verrucosa, his " verrues glandu-
laires," epithelial cones, consisting almost entirely of glandular cells, which press into the
mesoderm, and partly form entirely or almost entirely detached mesodermal islands of cells.
Here, however, we must consider the fact that, in the case of an extremely j>apillose
surface, the depressions and sinuses between the papillas may often resemble glands
in transverse sections, taken through the wall. I have never been able to convince myself
of the existence of glands in Bunodes minuta, which does not, however, refute the asser-
tions as to their presence in Bunodes verrucosa. It is safer anyhow to consider the
adhesion of foreign bodies as brought about, on the whole, not by means of sucking-cups,

KEPOKT ON THE ACTINIARIA. 17

but by mucous cells, and nematocysts, and to entirely obliterate the sucking papilla' from
the list of systematic characters.

With regard to the cinclides or pores of the wall, which are so extensively used
not only by Ehrenberg (Abhandl. d. Berliner Acad., 1832, Phys. CI., p. 225), but
also by Gosse, and still more by Milne-Edwards, I need only repeat what has been
already said. They are only distinct in a few forms, are questionable in most cases,
and therefore form a characteristic which is practically of no great use. The tentacles
form a much more important characteristic than the two already discussed, less on
account of their form and size, on which Ehrenberg lays such stress, than on account of
their arrangement and relation to the intraseptal spaces, which have hitherto only excep-
tionally been taken into consideration.

Ehrenberg's system was first essentially improved by Milne-Edwards and Gosse.
Milne-Edwards added, to those already made use of by Ehrenberg, some new systematic
characters, which undeniably indicated progress. The extended knowledge of species
which had meantime been acquired rendered it necessary to take the different nature
of the pedal disk in the Minyadinse, Cerianthidae, and Ilyanthidse into account in the
formation of the system ; we owe to a more exact anatomical knowledge the apprecia-
tion of the systematic value of the marginal spherules. On the other hand, it is difficult
to understand how Milne-Edwards came to found twro great groups, " actinines vulgaires "
and " actinines verruqueuses," on such a character as the papillose or smooth nature of
the surface of the body, which is in itself unimportant and in no case clearly marked.
His mode of expression is by no means well chosen with regard to another point.
When, for instance, Milne-Edwards divides the tentacles into retractile and non-
retractile, he lays stress upon a secondary point, and overlooks the much more important
behaviour of the upper margin of the wall wdiich can be drawn over the oral disk in
the former case but not in the latter. This varying action of the wall is the only point
of importance, because it is anatomically founded on the structure of the circular muscle.

What I have said about Milne-Edwards is also true, on the whole, of Gosse, as the
same distinguishing characters recur in his system, although he uses them in a <1 liferent
manner ; in consequence of this last circumstance the genera of Gosse and Milne-Edwards
are often not co-extensive. A step in advance is made, inasmuch as Gosse takes into
consideration in his descriptions the acontia, which he himself had discovered, but, <>n
the other hand, the inconsistencies of which he is guilty lay the English naturalist
open to the gravest criticism. How, for example, does it happen that the smooth
wall not pierced by cinclides is made the most important character of the Antheadse, and
in spite of this the genus Aiptasia, which has been separated from other genera chiefly
on account of the presence of cinclides and acontia, is placed in this family ? How can
the genus Phymactis, whose diagnosis rests upon the character " skin watted," be placed
among the Actiniadae in which the wall ought to be smooth ?

(ZOOL. CHALL. EXP. — PART XV. — 1882.) P 3

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

The more recent naturalists who have given systematic surveys of the Actinias, and
among them Fischer, Jourdan, Klunzinger (Korallthiere des rothen Meeres, Heft, i.),
and above all Verrill (Proc. Elliot Soc, vi., Comm., p. 69), sometimes follow Milne-
Edwards more closely, sometimes Gosse ; none of them have brought forward new or
comprehensive points of view.

Although the existing systems of the Actinias undeniably recpiire a complete re-
modelling on a new foundation, I have refrained from this at present, as the material
investigated by me was insufficient. I only considered it absolutely needful to form some
larger divisions anew, in order to express in some measure the conditions of relation-
ship among the forms. I have taken the structure and arrangement of the septa as
the fundamental principle, and distinguish six tribes of Actiniaria : (1) Hexactiniae,
(2)Paractinia3, (3) Monauleae, (4) Edwardsiae, (5) Zoantheae, (6) Cerianthese.

I have followed Gosse as far as possible in fixing the limits of the families, but my
great endeavour has been to define more sharply the meaningless characteristics hitherto
in use, by bringing more emphatically forward the anatomical characteristics predomin-
antly developed in the sej)arate families, such, for example, as the nature of the septa and
of the circular muscle, the presence of secondary tentacles and acontia (the latter may
appropriately replace the cinclides), and the distribution of the reproductive organs.
Thus, I have characterised the family of the Sagartidee afresh, as I have laid down
as essential that they should possess acontia and a mesodermal circular muscle, and
that the six pairs of principal septa should be distinguished from the rest by being
alone perfect, and not bearing reproductive organs. I found these conditions in a
whole series of forms belonging to the Sagartice, and if other species hitherto placed
among them do not agree in these respects, it is impossible that they should remain in
one and the same family.

As regards the definition of the species, I found myself in a difficult position. All the
specimens of the Challenger material before me were in a strongly contracted condition,
so that I could only form a very imperfect idea of their natural shape. Many of them
were, moreover, injured in being detached from the underlying substance or by the
dredging apparatus. The colour had gone entirely, almost without exception, and the
only information on this point was that given by Moseley about the few forms described
by him in the Transactions of the Linnean Society. Thus, nearly all the characteristics
on which former authors based their diagnoses of species were wanting. Verrill, who
has a most comprehensive systematic knowledge of Actiniae, declares that in such a
case all specimens only knowm in a preserved condition are scientifically of no use ; he
has therefore laid down as a fundamental principle, that only living forms, or those from
which drawings have been taken in a living condition, can be utilised for accurate
systematic description.

From this point of view, the Challenger material would have been, on the whole, of

REPORT ON THE ACTINIARIA. 1 <J

no use. Notwithstanding, I undertook to work it out, and extended my operations over
nearly all the specimens, because, according to my opinion, Zoology ought never to take up
a point of view, the effect of which would be that she musl remain excluded from a large
field of knowledge. In such cases it is rather the bounden duty of those who are
working out the material to discover characteristics by which the recognition of the
species is rendered possible, and this I believe I haw achieved. Whoever keeps in
view all the points taken into consideration in the description, the structure of the
tentacles, of the septa, of the oral disk, of the circular muscle, &c, should find no
difficulty or doubt in identifying a form with a living species, taking for granted that he
has gained a correspondingly accurate anatomical knowledge of the latter.

In conclusion, let me add a few words as to the state of preservation in winch the
material for investigation was handed over to me. As all naturalists who have had
much to do with Actinia? know from personal experience, the animals are difficult to
preserve, and require special attention in putting up. As such attention could not be
devoted to them in the Challenger expedition, many of the Actiniae did not fulfil the
demands made by any kind of accurate histological investigation. I regret especially
that many of the specimens had been first placed in chromic acid or chromate of potash,
and then in alcohol. These were so dry and friable that they fell asunder like tinder
under the slightest pressure ; methodical dissection was therefore impossible, especially
as even letting them lie for some time in water did not restore flexibility to the body.
Preservation in chromic acid and chromate of potash must therefore be avoided, as it
offers no advantages for histological investigation.

In many of the Actiniae, hardened in alcohol, the inner parts were likewise macerated,
perhaps because a large number had been placed in too small a quantity of alcohol, or
because ddute alcohol had been used. Anyonc^collecting Actinia? for examination ought
to attend to the following points. In the first place, it is advisable to keep the animals
separate till they are completely hardened, in order to prevent them from being flattened
while soft by pressing against each other. If this be not done, not only the form
but the sculpture of the surface suffers, which was often the case in the Challenger
material. In the second place, it is advisable to syringe the inside of the animal with
alcohol, placing the nozzle of the syringe through the mouth, or through a hole made in the
wall or the pedal disk. On the other hand, cutting or even halving of the living
animal is to be objected to, as in that case it is impossible to avoid the destruction
of many of the septa, and the parts will be displaced much more than in the ordinary
contraction of the animal.

In order to fulfil all requirements exactly, the Actinia before being preserved should
be subjected to a process which paralyses the muscles, such as has been previously
described by my brother and myself. This, however, requires more time and care than
can usually be bestowed by the collector on a single object.

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

DESCRIPTION OF SPECIES.

ACTINIARIA or MALACODERMATA.

Polyps with simple unpinnated tentacles and with septa, the number of which is
usually a multiple of six ; without skeleton. Body moving freely or adhering to sup-
porting substances by means of suction of the pedal disk, rarely firmly fixed. Animals
visually solitary, rarely forming colonies.

In the foregoing diagnosis I have placed the nature of the tentacles first as the only
thoroughly positive characteristic of the group ; it is by this that the Actinias are distin-
guished from the Anthozoa with pinnated tentacles, the Alcyonaria or Octactiniae. I have
been obliged to place second, and to limit the value of the hexamerous arrangement of
the septa, to which the chief importance was formerly attached, as the number of the
forms in which no settled number or even another number than six is the foundation of
the distribution of the septa is continually increasing. I have included the want of the
skeleton in the diagnosis, and therefore separated the Actiniae from the Corals, for
practical reasons ; the division is not a natural one. There can, however, be no
doubt, and this has been settled for some forms by observations, e.g., for Caryophyllia
cyaihus and Madrepora variabilis by G. v. Koch (Morphol. Jahrb., Bd. v., p. 316,
1880), that many Corals have the septal arrangement of the Hexactiniae, and therefore
approach this first section of the Actiniaria more closely than the remaining sections,
the Paractiniae, Edwardsiae, Zoantheae, and Ceriantheae.

Tribe I. Hexactixij;.

Actiniaria with paired septa. The septa of each pair are usually provided with
transverse muscular fibres on those faces which are turned from one another and
longitudinal muscular fibres on those faces which are turned towards one another, with
the exception of two pairs of directive septa, which are placed opposite one another,
and have longitudinal muscles on the faces turned from one another, and transverse
muscles on the faces turned towards one another. The number of the pairs of septa is at
least six, usually more, and then increasing in multiples of six. Mouth fissure-shaped ;
oesophagus with two oesophageal grooves and two oesophageal lappets.

Ehrenberg had the Hexactiniae and the Corals connected with them in view when he
separated his Zoocorallia polyactinia with more than twelve radii from the eight-rayed
Octactiniae. In the same way only they can lay claim to the name Hexacorallia bestowed
on them by Haeckel (Generelle Morphologic, Bd. ii., 1866). As they form the principal
part of the Actiniae, they have long been taken as types for the remainder. After
Haeckel had detached Cerianthus by reason of the observations on its development made
by Jules Haime, my brother and I pointed out the varying position of the Zoantheaa and

REPORT ON THE ACTINIARTA. 21

Edwardsire. The examination of the Challenger material has further confirmed the
correctness of this view, hut shows at the same time that the number of the varying
types is by no means exhausted.

Most corals will doubtless be placed later on with the Hexactinise ; perhaps a natural
division into forms having a skeleton and forms without skeleton may not be possible, as
even the closer limitation of the Hexactiniae given here does not exclude the possibility of
many of their families having more affinity to single families of corals than to other Hexac-
tiniae. At all events it is advisable to keep this possibility in view in investigating corals.

I shall discuss the families in an ascending series, according to the grade of their
organisation, and shall define the latter from two points of view. An Actinia is
placed lower down in the scale (l) the more uniformly the parts of the body are
developed, (2) the smaller the degree of histological differentiation. The first point
requires us to consider how far the septa resemble one another, how far the reproductive
organs are uniformly distributed, and so forth. From the second point we must keep in
view the nature of the muscular system ; is it preponderately ectodermal, endodermal, or
mesodermal, is there a circular muscle present and to what degree is it developed ? Further,
I consider the presence of the acontia, the cinclides, and the " bourses marginales " as
tokens of a higher organisation. Taken from this point of view, the Corallirnorphidse
are the lowest in every respect, the Sagartidse and Amphianthidse the highest.

Family, Corallimorphid.e, R. Hertwig.

Hexamerous Actiniae with a double corona of tentacles, a corona of marginal principal
tentacles, and a corona of intermediate accessory tentacles. Septa slightly differentiated,
all furnished with reproductive organs. Muscular system weak in all parts of the body.
No circular muscle.

CoralUmorph us, Moseley.

Corallimorphus, Moseley, 1877, Trans. Linn. Soc, ser ii., Zool., vol. i. p. 299.

Marginal and intermediate tentacles knobbed and distinguished from one another by
their size. The largest tentacles correspond to the first cycle of septa, the smallest to
the last cycle of septa and to the interseptal spaces ; no terminal tentacle-openings
(perforations through the extremities of the tentacles, see p. 8).

The family Coralliniorphidae is at present represented only by a single genus,
Corallimorphus, which was founded by Moseley for deep-sea Actiniae shortly after the
conclusion of the voyage of the Challenger, and divided into two species, Cored! imorphus
rigidus and Corallimorphiis profundus. It was considered most closely allied to Leuckart's
genus Discosoma (Ruppell, Reisc im nordl. Africa, 1828), and characterised as follows : —
" Body rigid, smooth, gelatinous, not contractile, without pores, but with an adherent base ;
disk circular and large ; tentacles non-retractile, elongate, conical, with a rounder! terminal

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

knob, of several sizes, disposed in regular series at the margin of the disk, and in two
circlets on its surface."

Setting aside such characters in this definition as are common to many Actiniae,
and are therefore only of secondary value for differential diagnosis, the following points
remain : — (1) The stiffness and slight contractility of the body, (2) the knobbed nature of
the tentacles, (3) their distribution in several series. I attach special importance to the
second and third characters, but the third requires to be more clearly defined, for it often
happens in the Actinise that some of the tentacles have migrated inwards, far on to
the disk, and are separated by a broad interspace from the marginal tentacles ; Moseley
has not taken into account a characteristic in the position of the tentacles which dis-
tinguishes the Corallimorphidae from nearly all true Actinise, viz., that two tentacles, a
marginal and an intermediate, communicate with the same intraseptal space. The
intermediate tentacles thus acquire special value, as they have not merely been pushed by
growth from the margin towards the centre, but may be considered as new formations of
independent origin. They are therefore distinctly opposed to the marginal tentacles,
have no homology with anything in most other Hexactinise, and consequently deserve
the special designation of " accessory" tentacles.

In considering the tentacles we must not forget their varying size, especially as it
reveals at the first glance the whole arrangement of the body of the Actinia. Of the
marginal tentacles six are the largest, and are distributed at equal distances, then follow
six more the next in size, which halve the interspaces between the first six, then twelve
which come in the interspaces between the first six and the second six, and so on. This
also holds good for the intermediate accessory tentacles, so that we can speak of tentacle
cycles of the first, second, and third orders which completely correspond to the cycles of
septa. The equalisation of the tentacles, which is elsewhere met with, has not made its
appearance, and the arrangement according to cycles, which must be regarded as a
primitive condition, still predominates.

An equally primitive condition is shown in the distribution of the reproductive
elements over all the septa, in the indistinctness of the cesojihageal grooves on the
oesophagus, and in the slight differentiation of the muscular system in all parts of the
body. The transverse and the longitudinal muscles form a uniform, hardly even slightly
pleated layer on the septa, so that both the strong retractor and the parietobasilar muscle
are still wanting ; the muscular layers on the oral disk and the tentacles are smooth, and
there is not the least indication of a special circular muscle. All this explains the small
capacity for movement in our animal, which is, moreover, due to the nature of the
supporting substance, which by its toughness reminds us of cartilage, and is richly
developed in the septa, the oral disk, and the wall.

The close relationship of the Corallimorphidee to Discosoma, which Moseley declared
probable, undeniably exists. Verrill was the first to point out (Proceedings Elliot Soc,

REPORT ON THE ACTINIARIA. 23

vi., Communications, p. G9) what was corroborated by Klunzinger (Korallthiere des rothen
Mfcivs, Heft i. p. 82, 1877), that the numerous tentacles, which in Discosoma (Verrill
and Klunzinger) and in tin- allied Homactis and Stephanactis (Verrill) are always
united in a radial series or a group, are connected with the same radial chamber. The
circular muscle seems also wanting in DLscosoma, as the animal is not able to draw
the wall over the oral disk. We might therefore incorporate the genus Cm-nil imor.
phus with Verrill's sub-family the Discostominaj, were it not for the difference thai
the secondary tentacles in Corallimorphus are limited to a single corona, whilst in
the Discostominse they appear in larger and variable numbers. This greater regularity
indicates an essentially higher grade of organisation in the Corallrmorphidae.

We must likewise bear in mind an affinity between the Corallimorphidse and Allmann's
genus Corynactis (Ann. Mag. Nat. Hist., ser. i., vol. xvii. p. 417), as in the latter the
tentacles end in a roundish head and are partly intermediate, partly marginal. Many
might also consider as points of affinity the facts that in both genera the nematoeysta
attain an extraordinary size, that both genera recall the skeleton-forming Zoantharia, and
that the nature of the mesoderm is the same in both. The cardinal point only remains
open to discussion, Are the intermediate tentacles secondary tentacles, which share the
intraseptal parts with the marginal tentacles, or have they merely been forced by growth
from the periphery towards the centre ? This eruestion cannot be settled by studying
either the drawings or the descriptions given by Allmann, Gosse, Klunzinger, and others.
Verrill also, who placed the genus Corynactis among the Discosomidse, considered it as
probable, but certainly not proved by actual observation that several tentacles arc
evasinated from each radial chamber.

Finally, it may not be superfluous to lay stress on this fact, that the double corona of
tentacles does not justify us in assuming any connection between the Corallimorphida! ami
the Cerianthidae, which also have a circle of accessory tentacles in the periphery of the
mouth ; for what turns the scale in the definition of the grade of relationship is that the
Cerianthidse have not yet attained to the characteristic paired arrangement of the septa.

As at present there is only one genus in the whole family, it depends upon the
degree of importance assigned to the special characters, whether we consider them to
be characteristic of the genus merely or of the whole family. The most important
undeniably are the double corona of tentacles, the equal distribution of the reproductive
elements, and the absence of the circular muscle, and for this reason I have included
these points in the diagnosis of the family.

Corallimorphus rigidus (IT. II. figs. 1 and 4-6 ; PI. IX. 11. VI : PI. XII. 1-7).

CordHimorjahus rigidus, Moseley, 1877, Trans. Linn. Soc , ser. ii., ZooL, vol. i. p. 301.
Number of the intermediate tentacles twenty-four, of the marginal forty-eight.
Origins of the septa, in the lower third of the wall and miter third of the pedal disk,
shown by swollen thickenings of the supporting plate.

24 THE VOYAGE OP H.M.S. CHALLENGER.

Habitat.— (a) Station 14G. December 29, 1873. Lat. 4G° 46' S., long. 45° 31' E.
Depth, 1375 fathoms. Three specimens, (b) Station 157. March 3, 1874. Lat. 53° 55'
S., long. 108° 35' E. Depth 1950 fathoms. One specimen, (c) Station 195. October 3,
1874. Lat. 4° 21' S., long. 129° 7' E. Depth, 1425 fathoms. One specimen.

Colour. — Not recognisable in a ; blue-violet in b (determined from a spirit specimen) ;
pale reddish-yellow in c (determined by Moseley in the fresh condition).

Dimensions. — Height, 1-2 cm. ; breadth of the oral disk, 2'5-6 cm. ; of the pedal
disk, T5-6 cm.

The specimen on which Moseley founded his characteristics of the species Corallimorphus
rigidus was not among the material handed over to me for investigation. He states that it
came from a depth of 1425 fathoms, and was taken between the Banda Islands and Amboyna
on October 3, 1874, On the other hand, two other bottles contained Corallimorphidae,
which answered, on the whole, to Moseley's description. The differences were merely those
of colour and form, which might be easily caused by preservation and by difference of
age, so that I considered it best to determine these specimens as Corallimorphus rigidus.

1 found one specimen in a bottle marked "Station 157; March 3, 1874; 1950
fathoms," which also contained a Cereus spinosus, and in another bottle — " Station
146; December 29, 1873; 1375 fathoms," — there were three specimens, along with a
number of other Actiniae. The first specimen was admirably preserved, and therefore
formed the principal object of my investigation. I shall deal with it exclusively in what
follows, recurring at the conclusion to the variations in the three other specimens.

The body of the animal is discoid, as the pedal disk and oral disk are of equal
size (6 cm.), and lie exactly parallel, whilst the height does not amount to more than

2 cm. The tentacles are deep blue-violet, the remainder of the body paler and even
whitish in some parts.

The pedal disk (fig. 5) is furnished with forty-eight ecpially distinct radial furrows,
which are limited to the outer third, and gradually become shallower as they run inwards ;
they do not correspond to the insertions of the septa, but to the interseptal spaces between
them. The margin of the pedal disk and lower part of the wall is slightly inverted
and indented, in such a way that an indentation comes in the interspace between each
two radial furrows.

The points at which the septa are inserted in the wall (fig. 4) are recognisable by
longitudinal furrows only half-way up the middle part ; they are otherwise covered
by pad-like thickenings, which are placed near the base in such a way that the furrow
between each two pads occupies the middle between the insertions of two septa. Moseley
also describes these pads, but gives them a different position, as he terms them " smooth,
slightly projecting, rounded ridges or costse, corresponding in position to the intervals
between the attachments of the mesenteries." The conditions differ somewhat near the
oral disk. Here there is a broad circular swelling, which is traversed by a number of

REPORT ON THE ACTINIARIA. 25

longitudinal furrows. All the swellings of the wall and of the pedal disk arc caused
by thickenings of the supporting substance.

The oral disk is smooth and very firm. Moseley has given a perfectly correct account
of the manner in which the tentacles are distributed on the oral disk. The principal
tentacles are placed on the margin, exactly where the oral disk and the wall meet
at right angles. Among these arc six tentacles, recognisable on closer observation
as the largest, which are disposed at equal distances, two of them, occupying the ends
of the sagittal diameter, running through the corners of the mouth. The next six
tentacles stand in the middle of the interspaces between the first six, which they nearly
equal in size. On the other hand, there is a noticeable difference of size between the last-
named six tentacles and the twelve following, and further between these twelve and the
twenty-four tentacles composing the last cycle. Whilst, therefore, there are in all forty-
eight marginal tentacles, the number of the intermediate tentacles only amounts to
twenty-four, which are distributed in three circles. Six tentacles, furthest in and nearest
the oral opening, are placed upon the same radii with the six marginal tentacles of the
first order ; six others follow a little further out, and twelve others still further out, the
former of which correspond to the marginal tentacles of the second, the latter to those of
the third order. The first-named six are the largest, but even they are hardly so large as
the smallest among the marginal tentacles.

All the tentacles are knobbed, and therefore consist of a stalk and an expanded vesicular
end. The stalk is stiff and thick-walled, and bears a very thin layer of ectodermal longi-
tudinal and endodermal circular muscular fibres. The head is thin-walled, without
muscles, and not pierced by a terminal opening.

The oral opening and the oesophagus are very small. The fissure-like form, usually
so distinct, is hardly recognisable, and has therefore been overlooked by Moseley. On
closer examination, however, we find even here the two oral angles and oesophageal
grooves, which differ very little from the numerous indentations of the oral margin and
the longitudinal furrow's running out from them. The corners of the mouth and of the
d'sophagus are more closely defined anatomically by the insertions of the directive septa.

There are altogether twenty-four pairs of septa : the first six, the principal septa,
and the following six, secondary septa, are fastened to the oesophagus, even though the
latter do not reach so far down as the former ; the remaining twrelve are imperfect. All
the septa are plates of equal strength, which is essentially due to the thickness of
the supporting lamella. The muscular system is extremely weak and simply arranged, as
transverse fibres run on the one side and longitudinal fibres on the other in what is
hardly even a slightly pleated layer. Septal stomata are wanting also in the complete
septa (fig. G).

The ovary, an oval body consisting merely of few broad transverse folds, lies in the
middle of each septum, not excepting the directive septa. The excellent state of

(ZOOL. UIIALL. EXP. PAKT XV. — 1882.) P 4

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

preservation allowed of a detailed histological examination, which on the one hand con-
firmed the view already put forward as to the endodermal origin of the reproductive organs,
and on the other threw new light on the nature of the filamental apparatus.

The youngest ovicells are placed on the margins of the ovary, especially on the lower
and upper ; they were unmistakably recognisable as ova from the size of 9 m upwards, and
then consisted almost entirely of the nucleus, surrounded by a thin mantle of protoplasm.
They lie between the bases of the epithelial cells, distinctly still outside the supporting
lamella, often united in small groups. So far CoraUimorphus confirmed what had
already been observed in CaMiactis (Sagartia) parasitica (Actinien, p. 88); but, on the
other hand, it was a new condition, that relatively large ova, measuring from 40-50 /* in
longitudinal diameter, were still found in the endoderm ; since thev were almost as long
as the epithelial cells, one end reached nearly as far as the surface. Twice I observed one
of these larger cells, which was clearly in the act of migrating into the mesoderm (figs. 2
and 3). It had an amoeboid, hour-glass-shaped, constricted body, of which one end lav
in the epitheUum, the other in the mesoderm ; the nucleus was mostly in the latter, but
the point of it projected into the former.

The ovicells enclosed in the mesoderm all appeared to me to have, from the first, the
filamental apparatus, though in different stages of development. In the largest, almost
mature ovicells (tig. 7), it is a corneal body, whose base rests on the surface of the ovum.
It likewise lies in the mesoderm, and its extreme point only reaches to the base of the
epithebum : in this way it is distinguished from the formation of the same name in
Calliactis, which belongs to the epithelium itself, and even projects as far as its upper
surface. The distinction is of no importance, and is clearly owing to the different
development of the connective tissue, which is very visible in CoraUimorphus, wlfilst
in Calliactis it is so scanty that the ovicells He close to one another, and only a delicate
supporting framework remains when they are taken away.

A second difference is of greater importance. In Calliactis it was not possible to dis-
tinguish nuclei in the filamental apparatus, which thus showed itself to be a differentiation
iff the ovum itself, whilst its cellular structure is very distinct in CoraUimorphus. The
apparatus consists of filament-shaped cells, carrying their nuclei on the base resting on
the ovicell. Preparations stained with carmine showed us here a corona of oval bodies
coloured red. It is possible that, in spite of all trouble taken, I did not succeed in find-
ing out the nuclei in Calliactis, because I was working with osmium preparations, in
which the nuclei often are difficult to colour. I might, however, have had to deal with
different stages of differentiation of the structure, and this is corroborated by the
following observations on the development of the apparatus in CoraUimorphus.

Young ovicells have a single finely striated process, piercing the supporting lamella, by
which they are fastened on the base of the epithelium. The epithebum is modified in a
peculiar fashion at the point in question ; wlfilst it is elsewhere overloaded with roundish

REPORT ON THE ACTINIARIA. 27

granules and shows an irregular distribution of its nuclei, its cells here become fine
filaments, reminding us of sense cells, which are thickest in the middle where the)- bear
their nucleus. They form a body which may be best compared in shape to a gustatory
bulb of the mammalia ; it is broad in the middle, but pointed above towards the
surface of the epithelium ami below towards the junction with the process of the ovum.
This constitution of the filaments! apparatus is rather a transition to Calliactis ; it seems
to me to indicate that the process of the ovicell only corresponds to the fibrous cord in
Calliactis, whilst the modified epithelial cells compose a newly added constituent.

The transition into the final condition can be followed in different ovicells, step by
step, through all the stages (fig. G). Whilst the process of the ovicell is contracted, the
epithelial cells penetrate the supporting substance. Their body, therefore, stdl lies with
the nucleus in the epithelium. The nuclei gradually migrate ; we first see only a few
on the surface of the ovicell, later on the number increases till we have the appearance
described above.

The peripheral part of the gastric cavity is divided by the twenty-four pairs of
septa into twenty-four intraseptal and twenty-four interseptal spaces. Twenty-four
intermediate tentacles and twenty-four marginal tentacles are connected with the
former, but only twenty-four marginal tentacles, and these the smallest, with the latter.
Two tentacles, an intermediate and a marginal, consequently belong to each intra-
space. (PI. II. fig. 6, shows an open intraseptal space with the two tentacles belonging
to it.)

The three other specimens of Corallimorphus rigidus were taken at another date
(29th December 1873), and in a different place, at a depth of 1375 fathoms; and as
the animal observed by Moseley belonged to a third locality, it appears that these Actiniae
are very widely distributed in the great depths.

There was little indication of the natural colouring in any of the three animals, as
their yellowish-brown hue was certainly referable to the change caused by the spirit.
They were all distinctly smaller ; one, plainly a very young specimen, was only 1 cm.
high, 2-5 cm. broad at the oral disk, and 1*5 cm. at the pedal disk. It had forty-eight
marginal tentacles arranged in the order already described ; on the other hand, there
were only twelve intermediate tentacles, the remaining twelve belonging to the third
cycle being still wanting. There were eight intermediate tentacles of the third cycle
in the specimen next in size, and ten in the third specimen. The last showed also most
striking irregularities in the number of the marginal tentacles, of which forty-two only
were observable.

The pad-like thickenings were wanting on the wall, and the insertion lines of the
septa were consecmently plainly indicated externally only by longitudinal furrows ;
in this respect the three specimens deviate from the typical Corallimorphus rigidus
and approach Corallimorphus p)rofundus. The histological character of the sup-

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

porting substance also varies. In Corattimorphus the cartilage-like consistency is
caused by a homogeneous matrix, which is richly excreted, and within which traces of a
fibrous tissue may still be recognised. In the specimen first described from Station 157
the fibrous mass is indistinct (PI. IX. fig. 11) ; on the other hand, in the last-named three
specimens (fig. 12) it is very distinct and sharply separated from the homogeneous funda-
mental substance, so that the latter forms a special layer contiguous to the endoderm.

Numerous small, ramified cells ai*e scattered in the supporting lamella ; some of
these contained vacuoles and a single space, filled with fluid, and surrounded by a thin
protoplasmic layer containing the nucleus. The vesicles of the cells were large and
numerous in the first specimen, but easily overlooked in the others, as they were rarely
met with and small in diameter.

The last-named diversity may be explained by admitting that the specimens are of
different ages, an admission which is supported by the difference in size, and which may
also explain differences in the muscular system, viz., that the ectodermal muscular layer
is a smooth lamella in the three smaller specimens, whilst in the larger one it is finely
folded. It is, however, advisable, under existing circumstances, to include all the four
individuals under the same name.

Finally, the specimen described by Moseley had a somewhat different shape,
inasmuch as the pedal disk was only half as large as the oral disk, so that the side walls
of the body diverged as in an inverted cone. But as it had the longitudinal swellings
on the wall described above, and the number and arrangement of the tentacles were
exactly the same as in the specimen on which my description is founded, I did not
consider it to the purpose to divide the material into two species.

Corattimorphus profundus, Moseley (PI. II. figs. 2 and 3).

Corattimorphus profundus, Moseley, 1877, Trans. Linn. Soc, ser. ii., Zool., voL i. p. 300.

Number of the intermediate tentacles limited to twelve, number of the marginal
tentacles, forty-eight. Mural membrane marked by longitudinal furrows corresponding
to the insertions of the septa.

Habitat,— (a) Station 293. November 1, 1875. Lat. 39° 4' S., long. 105° 5' W.
Depth, 2025 fathoms. One specimen. (6) Station 300. December 17, 1875. Lat. 33°
42' S., long. 78° 18' W. Depth, 1375 fathoms. One specimen.

Colour. — (Described from life by Moseley) in b, ochre-yellow, with dark radial madder-
coloured streaks, which are wanting in a.

Dimensions. — Height, 0*8 and 2"5 cm. ; breadth of the oral disk, 32 and 7"0 cm.; of
the pedal disk, 1'7 and 4*5 cm.

The characteristics by which Corattimorphus profundus is distinguished from
Corattimorphus rigidus are of a subordinate nature, so that I can include them in a short

REPORT ON THE ACTINIARIA. 29

description. Moreover, I had before me only the two specimens upon which Moseley
has founded the species.

According to Moseley, the colour is ochre-yellow, the large specimen having darker
madder-coloured radial streaks, of which traces were stdl visible. The base of the animal
was hollowed into a cavity, and enclosed a stone to which it was attached. The
insertions of the septa shone through it as white lines. The margin by which the base
passes into the mural membrane is indented, the wall itself furrowed longitudinally;
the number of furrows and indentations amounted to fifty. The oral disk is also
furrowed, though irregularly, in a radial direction, and has the small but distinctly
fissure-shaped opening in the centre.

Whilst the septa and reproductive organs show nothing new, the tentacles furnish
an important characteristic by which to distinguish Corallimorphus profundus from
Corallimorphus rigidus. This does not apply to the marginal principal tentacles, which
are likewise present to the number of forty-eight, and are also distinguished by their
different sizes, but to the intermediate accessory tentacles ; these are limited to twelve,
and clearly never go normally beyond this number, as one of the specimens examined was
larger than the largest specimen of Corallimorphus rigidus. In that one of the two
animals which furnished the drawing fig. 3 there was a small variation from what I have
laid down as typical, which, however, may be regarded as abnormal. As Moseley
observed, the number of the marginal tentacles has been increased by four, and amounts
to fifty-two ; instead of six secondary tentacles, halving the interspaces of the primary,
there are seven secondary tentacles, one more than usual in one of the interspaces.
It therefore follows that the twelve tertiary tentacles are increased by one, and
the twenty-four quaternary by two, making on the whole four tentacles more. An
increased growth has taken place in one of the sextants, which is shown also by the
intermediate secondary tentacles ; the sextant in question likewise contains two secondarv
tentacles of the second order, of which one, the supernumerary tentacle, is so small that
Moseley has quite overlooked it.

Moseley describes the reproductive organs, of which he draws twelve, as brownish
bodies showing visibly behind the thin wall. As there are twenty-four pairs of septa,
all of which bear reproductive organs, the number of the latter amounts to forty-eight.

Family, Antheomorphid.e, Hertwig.

Hexactiniae, with slightly developed muscular system, and long, slightly contractile
tentacles, without any circular muscles (tentacles consequently non-retractile) ; repro-
ductive organs present on all the septa ; numerous complete septa ; accessory tentacles
wanting.

I have associated under the name Antheomorphidaj Actinia?, which resemble in many

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

respects the following family, the Antheadae. Like the latter they have long tentacles, of
which the muscles are hut slightly developed, and which are consequently capable of a small
amount of contraction, and they are also unable to draw the upper margin of the wTah over
the oral disk. The most important difference between the two families is, that in the Antheo-
morphidae incapacity for protecting the oral disk is caused by complete want of the circular
muscle, whilst in the Antheadae it is owing to the muscle being only slightly developed.

The Antheomorphidae are easily distinguished from the Corallimorphidae by the absence
of the intermediate secondary tentacles ; in other respects the grade of development is
the same in both famdies. The principal tentacles form a single corona, which exactly
occupies the point of junction of the oral disk and the mural membrane. The muscular
layers of the oral disk and of the septa are hardly pleated at all. The reproductive
organs are developed on all the septa.

Besides the species described two other species should perhaps be added to this
family, but these were unfortunately not sufficiently well preserved to allow of detailed
examination. I have therefore inscribed them on the roll of doubtful forms under the
names of Porponia clongata and Porponia robusta.

Antheomorphe, n. gen.

Antheomorphidae with a corona of tentacles placed in a single row ; tentacles of
different sizes decreasing according to the orders ; wall smooth.

Antheomorphe elegans, n. sp. (PI. I. fig. 8).

Twenty-four extremely long marginal tentacles of different sizes, the six largest corre-
sponding to the six pairs of principal septa, the six middle to the six pairs of septa of
the second order, the twelve last to the interseptal spaces.

Habitat— Station 244. June 28, 1875. Lat. 35° 22' N., long. 169° 53' E. Depth,
2900 fathoms. Three specimens.

Dimensions. — Height, l"5-2-0 cm.; breadth, l"5-3'0 cm.

The three specimens upon which I founded the erection of the new genus and new
species were unfortunately not well preserved, so that I had almost to desist from any
examination of the inner parts, such as the septa with their muscular system. On the
other hand, the general form of the body was very well preserved.

The animals had been dredged from the depth of 2900 fathoms, and were attached to
stones by their extended bases. In the largest specimen the diameter of the base
amounted to 3 cm., whilst the height of the cylindrical body was only 2 cm., and the
diameter of the oral disk again 3 cm. The lines of origin of the septa shone distinctly
through the wall as twenty-four streaks ; these passed on to the oral disk, which was
somewhat raised and thickened in the periphery of the mouth. In one specimen the
mouth even rose like a proboscis above the upper surface of the peristome.

REPORT ON THE ACTINIARIA. 31

The twenty-four tentacles are of extraordinary length compared with the size of the
animal; the largest of them are 3-5 cm. long, whilst the smallest are only l"5-2"0 cm.,
the six others being of medium length. The tentacles have precisely the same arrange-
ment as in the Corallimorphida), so that the largest of them correspond to the intraseptal
spaces of the primary septa, the six following to the intraseptal spaces of the secondary
septa, and the twelve smallest communicate with the remaining interseptal spaces in the
periphery of the oesophagus..

We may therefore assuredly assume, from this distribution of the tentacles, that the
septa are arranged exactly on the same principle as in the other Hexactinise. This is
corroborated by the distinct presence of two oral angles in the mouth, and two oesophageal
furrows on the oesophagus. I was, however, only able, from personal observation, to
ascertain that the septa are arranged in pairs, and that all the twenty-four bore repro-
ductive organs.

The muscular system is nowhere mesodermal, the muscular lamellae are, moreover,
nowhere thickly pleated, either in the septa or in the tentacles and oral disk. The circular
muscle is consequently entirely wanting.

Family, Anthead^e, Gosse.

Hexactinias with long marginal tentacles and slightly developed endodermal circular
muscle (so that the oral disk cannot be covered at all, or only incompletely) ; numerous
septa, reaching for the most part up to the oesophagus, distinguished only by their size,
and all (?) furnished with reproductive organs.

The family of the Antheadae, of which the well-known Anthea cereus is the typical
representative, was erected by Gosse. Owing, however, to my having limited it here on
the basis of a more exact anatomical definition, it differs in extent from that given in
Gosse 's well-known work. On the one hand, I have separated from it the genus Aiptasia,
which has acontia and cinclides, following Verrill, who was the first to declare this
necessary (Comm. Essex Inst., vol. v. p. 322, 1866-7), whilst, on the other hand, I have
no hesitation in incorporating in this family the Actiniae with rough surface of the body,
inasmuch as they fulfil the above-mentioned conditions, whilst Gosse considers the
smooth surface of the wall as the most important characteristic.

According to my own observations, Anthea cereus has marginal spherules, though
these do not strike the eye by their bright colours, so that we cannot separate the An-
theadae from the Actinidae furnished with marginal spherules, on account of absence of
these formations ; it therefore becomes a question whether it would not be more to the
purpose to follow Verrill and unite the two families (Trans. Connect. Acad., vol. i. p. 491,
1867-71). As my own experience has shown that the nature of the circular muscle in
Actinia mesembryanthemum approaches that in Anthea cereus, I am inclined to answer

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

the question in the affirmative. In the meantime, however, we have no accurate
anatomical studies of this most abundant Anthozoon.

All Antheadae are easily recognised by their habit of body. As Verrill has already
specially remarked, the first thing which strikes the eye is the numerous, extremely long
tentacles, which spring from the junction of the wall and the oral disk. Their longi-
tudinal muscles are slightly pleated, and lie in the ectoderm, as they do also in the oral disk.
The circular muscle may easily be overlooked, as it is very small, and merely consists of a
few folds of the circular muscular layer of the wall ; hence the Antheadse are either in-
capable of drawing the wall over the oral disk, or can only do so slightly, and then very
slowly. The septa are very uniform, and the majority reach the oesophagus, so that
only the youngest and smallest are imperfect. Whether, as I presume, they are all fur-
nished with reproductive organs or not remains to be proved by further investigations, as
I have hitherto only examined immature animals.

Comactis, Milne-Edwards.

Antheadse with smooth body surface, with marginal spherules, which lie on a fold run-
ning outside the corona of tentacles.

Comactis fiagettifera, Milne-Edwards (PL III. fig. 5 ; PL VI. fig. 6 ; PL VIII. fig. 9)

Actinia flagellifera, Drayton, in Dana Explor. Exped., Zoopli., p. 126, pi. i. fig. 1, 1846.
Comactis flagdlif era, Milne-Edwards, Hist. d. Corall., torn. i. p. 236, 1857.
Comactis flagellifera, Verrill, Comni. Essex. Inst., vol. v. p. 323, 1867.

Marginal spherules on a fold, which is separated from the tentacles by a circular
depression. Tentacles moderately long, with distinct terminal opening, placed in two
to three rows. Body discoid.

Habitat.— Simon's Bay, Cape of Good Hope. Depth, 25 fathoms. One specimen.

Dimensions. — Height, 0"5 cm.; breadth, l"5-2'0 cm.

The small Actinia, which I define with some reserve as Comactis flag ell if era, came
from Simon's Bay, Cape of Good Hope, where it was dredged at the insignificant depth
of 25 fathoms. As no trace of reproductive organs could be found even on minute
investigation, it was, at all events, an immature animal, so that the above assertion as
to size cannot be considered as the standard for characterising the species.

The wall is smooth, for although the surface in the specimen before me was re-
peatedly wrinkled, both transversely and longitudinally, this was plainly owing merely
to the high degree of contraction of the animal. There are, moreover, two very distinct
circular constrictions, a lower one caused by the action of the parietobasilar muscle, which
divides the body into two equal parts, and an upper one lying close under the tentacles,
and caused by the circular muscle which runs there. Outside the latter the wall-

REPORT ON THE ACTINIARIA. 33

membrane forms a circular fold, with numerous small evaginations on its edge.
These correspond to the intraseptaJ and interseptal spaces, and must be compared to the
marginal spherules, which are found in the same situation in Actinia mesembry anthem nm,
and are conspicuous by their splendid colour ; they are, however, not so richly furnished
as in the above-named Actinia with the strongly refractive nematocysts, which Rotteken,
Schneider, and Duncan (Proc. Roy. Soc, London, vol. xxii. p. 263) held to be retinal rods,
and were thus led to regard the marginal spherules as eyes.

The circular muscle (PL VI. fig. 6) is not visible to the naked eye, as it is veiy
weak, and may be easily overlooked even under the microscope. The endodermal circular
muscular layer is only folded a little more thickly than at other points, and shows three to
four larger and a few smaller dendritic figures in transverse section. The folded muscular
lamellae, which are supported by relatively strong connective substance, project towards
the gastric space, and are not enclosed in the connective substance of the wall, and in
this way an insignificant circular swelling is formed. The nature of the circular muscle
as described above furnishes a further point of comparison with Anthea cereus, in which
the organ is only slightly stronger.

The tentacles are over a hundred in number, and lie in three circles close to the
peripheral margin of the oral disk ; the largest of them, belonging to the innermost circle,
are only 0"5 cm. long ; they are all thick-walled, and as thick at the rounded end as at
the base. They are pierced by a small terminal opening, wdiich is usually perceptible to the
naked eye, especially in tentacles from which the epithebum has been stripped off.

The longitudinal muscles in the ectoderm, which pass on to the oral disk as radial
fibres, recall in many respects the ectodermal muscular fibres in the wall of Cerianihus ;
they are borne by very thin supporting lamella?, which are slightly branched and
lie close together, though they never attain the same extraordinary length as in
Cerianthus (PI. VIII. fig. 9). Here and there we find isolated mesodermal bundles
of muscles, whose fibres correspond in their extreme fineness to the longitudinal
ectodermal muscles. As the wide oesophagus protrudes outwards the numerous longi-
tudinal streaks on it are almost obliterated. The oesophageal grooves are also some-
what indistinct, as the tube is folded irregularly here and there. There is no reason,
however, to question their existence, as I observed the directive septa in transverse
sections.

All the septa appeared to be perfect, though the youngest did not reach far down
the oesophagus. I could not settle their number accurately : the portion which I cut off.
and which I took to be about one-fourth of the entire animal, contained six pairs of two
different sizes, the smaller alternating regularly with the larger. This would give forty-
eight septa for the whole animal, which are distributed in three cycles, taking for granted
that this Actinia follows the hexamerous type. This view is so far warranted by the
undeniable approximation of Comactis flagellifera to the hexamerous Anthea cereus.

(ZOOL. CHALL. EXP. — FART XV. — 1882.) P 5

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3(j THE VOYAGE OF H.M.S. CHALLENGER.

The trunk, from which these nullifications proceed, being divided into two main
branches, two systems of supporting lamellae are present, radiating respectively one from
each of these ; the two systems are contiguous in the median plane of the muscle,
thus giving rise to repeated fusion of their respective supporting plates. The muscular
layers become consequently detached into bundles of muscles, and the endodermal
muscles partially transformed into mesodermal. The pleatings of the same system
rarely become connected with one another by lateral lamellae, though this is more
frequent at the point where the circular muscle passes transversely through a septum ;
indeed here they are often connected to such an extent that a great part of the muscular
fibrillar runs for some time entirely in the mesoderm.

In the upper half of the wall we find small endodermal evaginations, which grow like
glands into the underlying connective substance (PI. VIII. fig. 4), and show a streak of
blackish colouring in transverse section. Their csecal end nearly reaches the ectodermal
epithelium, but is always separated from it by a thin partition of connective substance,
so that we never find small openings comparable to cinclides. The colouring is caused
by the accumulation of black pigment granules in the endodermal epithelium. The
endodermal muscular layer is not so thickly pleated throughout the region of evagination
as in other parts of the wall. The evaginations seemed to me to be present only in the
intraseptal spaces, but they were so frequent there that many intraseptal spaces showed
three of them in radial section.

The oral disk and tentacles did not admit of detailed examination ; enough that
both parts possess an ectodermal, richly-pleated muscular lamella. The septa, on the
contrary, are of special interest, firstly, from the constitution of the muscular system,
and, secondly, from their arrangement (PI. VIII. figs. 3 and 5).

The longitudinal muscles of the septa are developed to an extent which I have
never met with in any other Actinia ; they form thick swellings, showing an ex-
tremely delicate figure in transverse section. The pleatings of the supporting substance,
which are covered with muscular fibres, are thickly branched, lie closely together, and
pass one between the other in such a way as to form in transverse section what one
might almost call a " meandrous complication," although the supporting layers never
absolutely become fused. The mass of the muscle actually projects above the surface of
the septum, and presents a mushroom-shaped appearance, caused by the constriction at
its base.

The muscular swellings lie on the septa till within a short distance from the wall and
from the oesophagus ; there the muscular fibrilke extend in a smooth layer, and only
become again more closely pleated when still nearer the wall. A slight parietobasilar
muscle on the side of the transverse muscular layer corresponds to this second longi-
tudinal cord.

All the septa are grouped in pairs in such a way that, with the exception of the two

REPORT ON THE ACTINIAPJA. 37

pairs of directive septa, the faces provided with longitudinal muscles are turned to one
another. The directive septa on both sides (fig. 5, rh) are formed very irregularly ; in
each pair one septum is very strong, whilst the other is rudimentary ; the latter never
reaches as far as the oesophagus, and was so small in one case that it was not possible to
perceive the manner in whieh the muscles were arranged.

The other pairs of septa vary in size, though they could not be divided into different
orders, as a series of strong, large septa, which have almost all attained to an equal degree
of development, is followed by a number of smaller septa ; the former reach to the
oesophagus, whilst the latter are imperfect. There were, on the whole, probably from
thirty to fort}' pairs of septa. This difference of size in the septa, and especially the
disproportion between the directive septa, is so unusual that it comes to be a question
whether the specimen examined was normally developed.

Tealia bunodiformis belongs to those species in whieh I have observed that two
adjacent septa may be connected by their free margins. In such cases it is two septa of
different adjacent pairs which pass continuously into one another inside the strong
longitudinal swellings.

The reproductive organs of the animal examined were ovaries, and were found on all
the septa, except on those which were behindhand in their development. Two of the
directive septa were consequently sterile, whilst the other two were furnished with
reproductive organs.

Tealia bunodiformis differs very markedly from Tealia crassicornis. In Tealia
bunodiformis the muscular fibres of the tentacles and oral disk are ectodermal, whilst in
Tealia crassicornis they have passed into the mesoderm; in the former, reproductive
organs are present on the septa of the first and second order, whilst in the latter they
are absent. It may, therefore, perhaps be well at some future time to make Tealia
bunodiformis represent a new genus distinct from Tealia crassicornis. I have chosen
the name "bunodiformis," because in some parts the warts are grouped in longitudinal
rows, and therefore have the same arrangement which characterises the genus Bunodes.

Leiotealia, Hertwig.

Tealidse with smooth body surface, without warts, and without spherules, but with
longitudinal furrows corresponding to the insertions of the septa ; tentacles of equal
size, arranged in several rows.

Leiotealia, as the name shows, is a Tealia with smooth body surface, and therefore
bears the same relation to the true Tealia as Paractis does to Tealidium. According
to Milne-Edwards they belong to the genus Paractis, from which I have separated
them on account of the endodermal position of the circular muscle.

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

Leiotealia nymphcea (PL VII. figs. 1-5).

Actinia nymphcea, Drayton, in Dana. ExpL Exp., Zooph., p. 146, pL iv. fig. 33 (Synopsis, p. 10),

1846.
Paraciis (?) nymphcea, Milne-Edwards, Hist, des Corall, torn. i. p. 252, 1857.
Sagartia (?) nymphcea, Verrill, Trans. Connect. Acad., vol. i. p. 486, 1871.

Tentacles short, in three rows, body constricted half-way up by a special circular
muscle, insertions of the septa shining through the wall as longitudinal lines.

Habitat. — Station 149. Christmas Harbour, Kerguelen. January 29, 1874.
Depth, 120 fathoms. One specimen.

Dimensions. — Height, 1 cm. ; breadth of the base, 2 cm.

This small Actinia, of which there was only a single specimen, was examined in a
strongly contracted condition. The oral disk was completely inverted, and the margin of
the peristome drawn over it, so that only a narrow passage was left ; at two-thirds of the
height the body showed a circular constriction, caused, as we shall see, by a special
muscle, which is wanting in most Actinias.

The surface of the body in Leiotealia nymphcea is perfectly smooth, and so thin that
the origins of the septa, which number more than a hundred, shine distinctly through it,
in the form of white lines. Muscular fibres are present only on the endodermal side,
and form a smooth layer, which, from the contraction of the animal, was only slightly
pleated, though it was thickened at two places into distinct sphincters. The upper
sphincter is the more powerful, and corresponds to the sphincters of other Actinia? in its
position, immediately under the margin of the peristome, and in its action, for like them it
draws the wall together like a bag ; it is a circumscribed muscle, and projects into the
stomach as a circular swelling, which is only fastened to the wall by a narrow base, and
pierces the origins of the septa. Seen in transverse section (PL VII. figs. 2 and 4)
a process of the supporting lamella of the wall makes its way into the inside of the
swelling, and traverses it nearly to the opposite end ; it thus divides the swelling into
1 wo parts, the upper being about three times as broad as the lower, which pass into one
another at the free end of the process. Unless the section passes through the precise
point where the sphincter pierces the septum, each part shows on the surface a layer of
epithelium, and inside the repeatedly folded muscular lamella, supported by very fine
folds of connective tissue. The folds of connective tissue spring from the axis of
connective tissue, and throw out irregularly several lateral branches, all equally covered
with muscular fibrillar. The spaces between the folds of connective tissue are open
towards the epithelium, so that the latter passes in between them. The lower ends of
the pleatings of the muscle are rarely detached, so as to form flat mesodermal bundles of
fibrillse ; this takes place more frequently at the free end of the axis of connective tissue.

The lower circular muscle (figs. 2 and 5, ms') is less highly developed; to the naked
eye it shows as a narrow palish-yellow tract, running upwards and downwards ; seen

REPORT ON THE ACTINIARIA. C9

under the microscope, it consists of a muscular lamella pleated into unbranched folds,
which lie closely together like the leaves of a book, are highest in the middle of the
tract, and gradually decrease in size on either side till they pass into the smooth
fibrillar layer of the wall.

The constitution of the oral disk of the specimen examined could not accurately be
determined, as it was closely folded in consequence of the extreme contraction. Its
peripheral margin bore three alternating rows of tiny tentacles, which only projected
like small buttons, and corresponded in number to the individual septa. On transverse
section, the tentacles of the inner circle proved to be evaginations of the intraseptal,
whilst those of the outer circles belonged to the interseptal spaces.

The radial muscular fibres of the oral disk (PI. VII. fig. 1) are mesodermal, but
otherwise only slightly developed. Sparse thin bundles are separated from the ectoderm
by a narrow layer of connective substance, and connected like a net with one
another by an interchange of fibres. They enter the bases of the tentacles and extend to
their points. There were apparently no openings in the tentacles.

The pedal disk is of no great interest. A small circular ridge, caused by a thickening
of the supporting lamella, ran on its inner side between the septa, at a little distance
from and parallel to the margin. As I only examined a single specimen of this Actinia,
it is impossible to determine whether this structure is constant or not.

The species before us is chiefly characterised by the size and disposition of the septa,
of which I therefore give a more detailed description. It is difficult, on the whole, to
recognise in their arrangement the regularity shown by the Hexactinise. The six
pairs of principal septa, of which two he as directive septa in the sagittal axis, are
certainly distinguished at once by their size, but the six pairs of the second order are
very small, and in this respect fall short of the twelve pairs of the third order. All the
septa already mentioned reach to the oesophagus, whilst those following are imperfect.
Of these the twenty-four pairs of septa of the fourth order are always present, but un-
equally developed, being larger in the neighbourhood of the principal septa, smaller in
the neighbourhood of the septa of the second order. This latter region is, therefore,
plainly retarded in growth, and this becomes still more conspicuous in the following
septa. In the interseptal spaces, which are contiguous to the septa of the second
order, the septa of the fifth order are extremely small, and those of the sixth order
are stfll completely wanting. On the other hand, in the neighbourhood of the principal
septa, the septa of the sixth order are already as large as those of the fifth order. It is,
however, quite possible that the nregularities just described become equalised in the
course of growth, as the specimen examined was a young animal without any indication
at all of reproductive organs.

The muscles of the septa show peculiar conditions, especially the longitudinal and
parietobasilar muscles. The former is only distinctly present on the septa of the firsl

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

throe orders, ami except in the directive septa projects into the intrascptal space ; it is a
powerful muscular protuberance, which begins at nearly equal distances from the middle
point and tlir periphery of the pedal disk, becomes distended half-way up, and then gradu-
ally becomes narrower till it is inserted at the oral disk inside the tentacles (PI. VII. fig. 5).
The muscular protuberance lies almost freely on the surface of the septum, and is only
fastened to it near its adaxial margin by a kind of mesentery. In transverse section, it
therefore shows (fig. 3) a figure resembling a mushroom-shaped excrescence, a broad mass
from which a stalk thrust to one side passes up to the septum. The connective substance
of the septum enters through the stalk into the longitudinal muscle, where, seen in
transverse section, it becomes dendritically branched. The ramified lainelke of connective
tissue, which produce the dendritic figure in transverse section, are covered by a con-
tinuous layer of muscular fibrilke ; the whole is covered with epithelium, which reaches
to the bottom of the interstices between the layers of connective tissue, so that the
endodermal muscular fibres never become transformed into mesodermal fibres.

The longitudinal muscle described above is part of the layer of longitudinal fibres,
which is slightly folded in other places, and shows in transverse section a second smaller
dendritic figure at the base of the septum only. Opposite it, on the other side of the
septum, we reach the site of the transverse muscular fibres, which are directed trans-
versely from the wall towards the axis of the body of the Actinia, and as usual are
strongest in the upper third. The parietobasilar muscle is found on the same side, where
it can be distinctly recognised as originating by a pleating of the transverse muscular
layer. It is, in fact, simply a crescentic fold lying loosely on the septum, so that a pouch-
shaped space opening into the stomach, into which one can thrust the point of a needle,
always runs in between the two parts. The fold is covered on both sides with an ample
muscular layer running parallel to the margin of the fold. The parietobasilar muscle
springs from the pedal disk, from its margin nearly to its middle, after which it is
attached to the wall as far up as the lower circular muscle. When the animal is
contracted it draws the pedal disk and the wall nearer one another, and as the former
is the part which is more easily moved, it becomes arched upwards, and so forms a slightly
depressed sucker ; the muscle therefore plays an important part in attaching the body
of the Actinia to the ground beneath. As regards septal stomata, the inner or peristomial
appear to be present, whilst the outer or marginal are certainly wanting.

I consider the small Actinia described above as identical with a small form found by
Dana, near Valparaiso, in the American expedition under Captain Wilkes. According to
Dana's description, the whole animal is whitish, with a touch of yellowish-brown, the oral
disk pale flesh-colour, and the tentacles yellow. Drayton gave it the name of Actinia
ntjmphcea, which was afterwards changed by Milne-Edwards into Paractis nymphcea ;
finally, Verrill included the species with a mark of interrogation in the genus Sagartia,
for which, however, there is no sufficient ground.

REPORT ON THE ACTINIARIA. 41

Family, Paractid^e, Hertwig.

Hexactiniae, with numerous perfect septa, arid with very contractile, moderately long
tentacles, which can be completely covered ; circular muscle very strong, mesodermal.

The Paractidse form a family parallel to the Tealidse; they agree with the latter in tin-
nature of the septa and the tentacles, hut differ from them in the nature of the circular
muscle. The lat frr is enclosed in the mesoderm, and either lies close under the endoderm
or is forcibly separated from the epithelium by the secretion of abundant connective
tissue. In this family, as in the Tealidas, I include not merely the animals with
smooth body (genera Paractis and Dysactis), but also the papillose forms of the genera
Tealidium and Antholoba.

Paractis, Milne-Edwards.

Paractidse with smooth body surface, without papillae and without marginal spherules ;
tentacles nearly equal in length and in strength ; numerous longitudinal furrows of the
wall

The genus Paractis was founded by Milne-Edwards for Actinia?, of which the wall
has neither papillae nor marginal spherules, but can be drawn completely over the oral
disk and tentacles ; the tentacles are said, moreover, to be nearly equal in length.

Two forms of the Challenger material fulfilled these requirements ; they differed, how-
ever, in one very important point, as the circular muscle was endodermal in the one, meso-
dermal in the other. The former consequently belongs to the famdy of the Tealidse,
and for it I have composed the new name Leiotealia, whilst for the latter I have
retained the name Paractis.

Paractis excavata, n. sp. (PI. I. fig. 6, PL XL figs 13, 14).

Wall with more than fifty longitudinal furrows, corresponding to the septa, oral disk
hollowed like a dish, with two rows of tentacles, the outer somewhat larger than the inner ;
tentacles thick walled, with strong mesodermal muscles, which are present only on the
adaxial side at the base, but surround the tentacles on all sides towards the point.

Habitat.— Station 300. December 17, 1875. Lat. 33° 42' S., long 78° 18' W.
Depth, 1375 fathoms. One specimen.

Dimensions. — Diameter of the pedal disk, 2 "5 cm., of the extended oral disk, 6 cm.
Height of the wall in the contracted animal 2*5 cm., from the pedal disk to the margin of
the mouth 1 cm.

Paractis excavata, which I describe as a new species, founded by me upon a single
specimen, is one of the most characteristic forms of the Challenger material, both as to
the shape of the body, and as to its finer structure.

(ZOOL. CHALL. EXP. — PART XV. — 1882.) P 6

4-2 THE VOYAGE OF H.M.S. CHALLENGER.

In the strongly contracted condition, shown by the specimen, the body appears to be
as hio-h as broad, and also of equal breadth in the region of the pedal and of the oral
ili-ks. On dissecting the animal, however, it becomes evident that if the height of the
animal is to be determined by the distance of the oral margin, from the pedal disk, it will
fall far short of the breadth, and, moreover, that the diameter of the contracted oral disk
is considerably greater than that of the pedal disk, which it must have exceeded twice
at least. When fully extended, our Actinia must have been shaped like a dish, the
wall diverging from the narrow base towards the broad oral disk.

The wall rises from the margin of the moderately firm pedal disk, which measures
about 2 5 cm. in diameter, and is irregularly wrinkled and furrowed, to a height of about
3-0 cm. ; it is covered with fifty -four longitudinal furrows, which are separated from one
another by equal intervals, and reach from the lower to the upper margin of the wall.
These longitudinal furrows are crossed in the lower part of the wall, by irregidar trans-
verse furrows, which become more indistinct towards the upper part. The wrinkled and
knobby appearance of the lower part of the wall thus produced I consider to be the
consequence of the high grade of contraction of the animal.

The wall is firm like leather, but of no great thickness ; only that portion of it con-
tiguous to the oral disk is distended about 0"5 cm. by the contained mesodermal circular
muscle. The bundles of the latter are small, and composed merely of a few fibrillae ; they
run irregularly, either singly or united in groups in the fibrous connective substance.
They are separated from the ectoderm by a broad interspace, but extend nearly to the
circular muscular layer of the endoderm, and are even connected with it in some parts,
so that steady growth of the circular muscle undeniably takes place by the transformation
of endodermal elements into mesodermal. The principal mass of the circular muscle still
extends downwards a little way, in a layer of mesodermal bundles of fibres, lying close
under the endoderm.

The oral disk bears fifty marginal tentacles, and is covered with an equal number
of radial furrows, which begin at the oral margin and end between each two
tentacles. The radial swellings lying between the furrows are flattest near the mouth,
and become more distinct in proj)ortion as we approach the tentacles. This proceeds
from the distribution of the muscles, which are very weak near the oral margin, and
become stronger towards the periphery till they swell out into the powerful muscular
masses of the tentacles. The muscular nbrillaB are remarkably strong, partly perhaps in
consequence of having swollen from the unsatisfactory state of preservation. Their
principal mass lies united in thick bundles in the mesoderm ; where the muscular system
is weak the bundles are scanty, and the separating tracts of connective tissue broad, whilst
towards the corona of tentacles the bundles lie close to one another, and the fundamental
substance becomes a slender framework. As muscular fibres still remain in the ecto-
derm the oral disk, if well preserved, would furnish an admirable subject for studying

REFORT ON THE ACTINIARIA. 43

the different stages by which the ectodermal muscles are transformed into mesodermal.
As far as I could observe the supporting substance rises on the surface of the disk in
numerous folds covered with muscular fibrillar

The tentacles are placed in two alternating rows, those of the inner row being rather
shorter and weaker than those of the outer row, whose length in a contracted condition
was 1"0-1'3 cm. They are thick-walled at the base, and run out into a fine point,
without any terminal opening. The)- are all strongly bent inwards, and have a hook-like
shape, which is caused by the distribution of the muscles. In most Actiniae, as we know,
the muscles surround the tentacles uniformly, but in Paractis excavata they are crowded
together towards the adaxial side where they form a muscular pad, which I have never
found equalled in strength in any other Actinia. In the tranverse sections (PI. XL fig.
1 4) the muscular fibrillas lie close together, and the framework of connective tissue is com-
pletely hidden, and only becomes distinct by appropriate staining ; it forms a network
whose meshes are small near the supporting lamella, but large and longish towards the
epithelium, enclosing spaces lying perpendicular to the surface of the tentacle. The
surface of the tentacles was not well preserved, so that I could not determine whether
these spaces were completely closed, or whether they communicate here and there with
the epithelium, which appears to me more probable.

Over one half the circumference of the tentacle the muscular layer is of uniform
thickness, but thins out over the remaining half into a delicate membrane, which
seemed to me to be wanting at the base of the tentacle, unless perhaps it had been
rubbed off. In spite of the varying strength of muscular layer, the thickness of the
tentacle wall is essentially the same all through in transverse section, as the connective
tissue substance becomes thinner in proportion as the muscular layer becomes
thicker.

It is, however, only the lower third of the tentacle which comports itself in the
manner above described, a transverse section through the point presents an essentially
different figure. The muscular layer is weaker indeed but present on all sides, it merely
becomes a little smaller for a short space on the abaxial side than on other parts of the
transverse section. A series of transverse sections rising from the base to the point shows
all the transitions between the two extremes, and we can follow step by step the process
by which the muscular layer, which originally lies only on one side of the tentacle,
gradually surrounds it entirely. I have only figured three transverse sections of such
a series, of which one is taken at the base (fig. 13, c), the second (fig. 13, 6) from the
middle, and the third (fig. 13, a) from the point. In all of these the thickness of the
muscular layer is indicated by hatching.

The oesophagus is very short, corresponding to the height of the animal ; it is furnished
with two oesophageal grooves, and eighteen longitudinal swellings. Six pairs of septa
of the first order, and six pairs of the second order, are inserted in the cesophagusj

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

besides which there are twelve pairs of imperfect septa of the third order. Septal stoniata
are wanting throughout. The parietobasilar muscle reaches to about one-fourth of the
height of the wall, where it gives rise to a circular constriction.

All the septa bore reproductive organs. As the animal examined was a female, I
was able to prove the existence of the filamental apparatus, which most resembles that
of Calliactis pa7xtsitica. A conical process rises on the surface of the ovum, the point
of which pierces the supporting lamella, and reaches to the free surface of the epithelium.
The specimen was, unfortunately, not sufficiently well preserved to determine whether
the process is formed of special cells, or is part of the ovicell itself.

Paractis excavata is perhaps allied to the Actinia peruviana of Lesson (Voyage de
la Coquille, Zoologie, torn. ii. part ii., 2, p. 75 ; Zoophytes, pi. ii. fig. 3) ; the number, form,
and arrangement of the tentacles, and the expansion of the body at the upper end is
common to both. The longitudinal furrows on the outside of the wall, which are so
distinct in Paractis excavata, are however wanting in the Actinia (Paractis) peruviana;
there are said to be merely " quelques plissures brunatres " present on the lowest section
of the wall.

Dysactis, Mdne-Edwards.

Paractidaa with smooth body surface, without papilla?, and without marginal spherules ;
tentacles very unequal in size, the inner essentially larger than the outer, completely
retractile.

I have kept essentially to the definition of the genus Dysactis, as given by Milne-
Edwards ; differing from him only in one subordinate point, for while he limits the
number of the rows of tentacles unnecessarily to two, I make no definite assertion on this
point. I differ more decidedly from Verrill (Mem. Boston Soc, vol. i. p. 26. 1866-69),
who has placed the genus Dysactis among the Antheadae, and consequently makes it the
most important character of the genus, that the wall cannot be drawn over the oral disk
and tentacles. I do not understand why VerrUl should differ in opinion from Milne-
Edwards, who has placed the genus Dysactis among the forms with retractile tentacles.

Dysactis crassicornis, n. sp. (PI. VII. figs. 6-12).

Height of the body rather greater than the breadth ; tentacles short, thick-walled
and conical, arranged in four to five rows, and decreasing in size from within outwards,
24 tentacles in the first row, 24 in the second, 48 in the third, &c.

Habitat— (a) Station 312. January 13, 1876. Lat. 53° 38' S., long. 70° 56' W.
Depth, 10 to 15 fathoms. One specimen, (b) Station 313. January 20, 1876. Lat. 52°
20' S. long., 68° 0' W. Depth, 55 fathoms. Four specimens.

Dimensions. — Height, 4-7 cm. ; diameter of the pedal disk, 3-7 cm.

I made Dysactis crassicornis the subject of detailed examination, as there were

REPORT ON THE ACTINIARIA. 45

several points about it which seemed to indicate it as a suitable object for such a purpose.
In the first place the unusual size of the body is favourable to dissection by means of
knives and scissors, and in the second place, it was represented in the Challenger
material by a large number of tolerably well preserved specimens. Two of the indi-
viduals were in a state of intense contraction, whilst in the other three the tentacles still
projected through the opening formed by the upper margin of the half-contracted wall.

The pedal disk is moderately thick, irregularly waited on the surface, otherwise
Hat. It passes at right angles into the wall, of which the surface ^s perfectly smooth,
except in the upper part, which is folded longitudinally in consequence of the contraction
of the circular muscle. Most of the animals are distended like a drum, as sometimes
happens in the Actinia?, so that the wall has become a thin membrane with the
origins of the septa shining through it. At its upper margin only, where it is con-
nected with the oral disk, the wall becomes thickened to from four to five times its usual
strength (fig. 12), and shows in transverse section a yellowish tract, lying in whitish
fundamental tissue close under the endoderm, which is caused by the circular muscle
running in this part.

The bundles of fibrillae appear in transverse section (PI. VII. fig. 7) as roundish or
repeatedly indented figures, whose periphery consists of a corona of fine fibres, but whose
centre appears in the spirit material almost empty, whilst in the living animal it is
filled with protoplasm and the nuclei of the muscular corpuscles. The bundles of
fibrillae lie so closely together in the fibrous fundamental tissue of the mesoderm that it
is hardly possible to determine distinctly whether or not they are united into smaller
and larger groups. As the section shows, they become divided and united by anas-
tomoses into an annular plexus, lying parallel to the course of the fibrillae, i.e., parallel to
the pedal disk (fig. 9).

Different points in the distribution of the bundles of fibrillae favour the view that the
mesodermal bundles originate in the endoderm, and only become deposited secondarily
by detachment in the mesoderm, where they increase still more by division and separa-
tion. The bundles of fibrillae lie usually in layers parallel to the endodermal surface, as
a few more compact layers of supporting substance extend through the mass of the
bundles parallel to the endoderm. The largest bundles are placed nearer the ectoderm,
where they are separated from one another by broader layers of connective substance,
whilst the smallest bundles (fig. 8) lie close under the endoderm, and — what is the
most important point — are connected here and there with the circular layer of fibres
wdiich run on the endodermal surface of the mesoderm.

The oral disk is covered with numerous shallow furrows, running from the oral margin
towards the tentacles. Their radial muscles form a tolerably broad stratum in the meso-
derm, and this is separated from the ectoderm by a thin, and from the endoderm by a
thick, layer of connective substance (PI. VII. figs. 10 and 11). This stratum is again com-

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

posed of bundles of fibrillse, which are chiefly flattened in a lateral direction, so that
the st ratuni seems to consist merely of apposed bands of muscles. As each band is
repeatedly indented laterally, and can be dissected into separate pieces lying one below
the other, they give rise to the very complicated formation shown in fig. 10, which is
specially striking from the close apposition of the bundles of fibrdlse.

The bundles of fibrillse are more scattered in the younger animals ; smaller bundles
of fibrilke are also found here lying towards the ectoderm in the intermediate layer of
connective tissue. It is quite conceivable that these smaller bundles may have migrated
from the ectoderm into the mesoderm, in order to supplement the mesodermal muscular
layer. The state of preservation of the material did not allow me to confirm this sup-
position, as I could not make out whether or not radial muscular fibres were persistent
in the ectoderm. In the peripheral part of the oral disk the bundles of fibrillse pass
into the tentacles, where they preserve exactly the same arrangement and position in
the mesoderm.

The corona of tentacles is immediately contiguous to the wall, whilst in Tealia
crassicornis, which in other respects is not unlike Dysactis in its general habit of body,
it is separated from the wall by a portion of the oral disk capable of becoming pleated.
The corona consists of several hundred tentacles, which are distributed in four to five rows,
and decrease distinctly in size from within outwards. If we examine an animal which
is developed uniformly in all sextants, we find twenty-four tentacles in the first or inner-
most row, and twenty-four tentacles also in the second row, which alternate with the
preceding twenty-four. In the third row the number rises at once to forty-eight, which
are placed in such a way that they alternate both with the twenty-four tentacles of the
first row, and the twenty-four of the second row. In the fourth row the number is
again doubled, so that it consists altogether of ninety-six tentacles, which still alternate
with all the preceding tentacles. The last row is' always irregularly developed; the
number of tentacles ought to amount to 192, but only came to some 90.

It will be seen at once from this mode of arrangement that all the tentacles of
Dysactis — and this applies to almost all Actinia? — lie in different radii, and must therefore
belong to different radial chambers ; they are merely parts of a single circle which have
become distributed in different rows, from being displaced in the course of growth. It
follows necessarily, from the whole mode of arrangement, that the separate rows of
tentacles stand in regular relation to the radial chambers, as the same principle of
arrangement, viz., that each cycle contains the same number of units as all the preceding
taken together, applies to both. From my own observation in making preparations,
I am convinced that the twenty-four tentacles of the first series belong to the twenty-
four intraseptal spaces of the septa of the first to the third orders, the next twenty-four
tentacles to the twenty-four intraseptal spaces of the fourth order, and so on.

Exceptions occur to the conditions which I have laid down as regular, but these can

REPORT ON THE ACTINIARIA. 47

be easily explained by the fact that growth is not equally rapid in different sextants,
or even in the separate parts of the same sextant. For example, in one sextant of a
Dysactis, in which the first circle consisted of only eighteen tentacles, I found that the
tentacles really corresponding to the septa of the third order were still in the second row,
and that all the following tentacles were correspondingly a row in arrears ; the first row
in the said sextant only contained two tentacles instead of four.

Terminal openings are wanting in all the tentacles. In consequence of the strongly
developed mesodermal muscles they are unusually thick-walled, on account of which I
have named the species " crassicornis." The largest of them, the tentacles of the first
row, are not 1 cm. long in a contracted condition, whilst they spring from a base of
considerable size whose diameter in a radial direction nearly equals the height of the
tentacle. The tentacles have therefore the form of short cones, flattened in a tangential
direction ; seen from the side of the radial chambers they extend like wide-mouthed
pouches, running to a point.

The tentacles lying towards the outside not only become smaller but, above all,
narrower at the base, and consequently more slender. The outermost tentacles are so
small that they merely project like small knobs above the surface of the oral disk.

The oral fissure is bordered by twelve broad, swelling papilla?, of which two at either
end enclose the entrance to the oesophageal grooves. They are stronger than the others,
and are, moreover, divided by a horizontal furrow into two swellings lying one above the
other. Whilst the oesophagus itself is short, its sagittal prolongations, the oesophageal
lappets are very long, and extend nearly as far as the pedal disk.

The number of the septa is very large, and in the oldest animal amounted to ninety-six
pairs, which were distributed in five cycles. In many places there were additional
indications of the ninety-six septa of the sixth cycle, which however merely projected as
thin folds between the wall and the pedal disk, and as yet had no mesenteric filaments.

We can generally distinguish two parts in the septa, one thick walled and
muscular, the other delicate and veil-like (fig. 12). The former lies on the wall ; its
longitudinal fibres spring not only from the pedal disk but also from the lower part of
the wall, and converge towards the oral disk and the oesophagus, especially towards the
base of the tentacles. We cannot precisely talk of a special longitudinal muscle, but
still the fibres are more thickly compacted in the middle of the lamella and united into
thick cords, showing the following figure in transverse section (PL VII. fig. 6). Under-
neath each cord lies a thickening of the supporting substance of the septa, which sends
out bushily branched folds of connective tissue in all directions, and these again bear the
richly pleated muscular lamella. The whole is covered with epithelium, which also has
hollows corresponding to the depressions between the ridges of connective tissue, so that
the inequalities caused by the distribution of the muscles also become visible externally.

The transverse muscles, which run from the wall principally towards the stomach, but

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

also towards the oral disk and pedal disk, are weak in the lower parts, but veiy strong at
the upper end. The upper portion draws the oral disk very energetically towards the
wall, and is assisted in this by part of the longitudinal fibres. The interspace between
the oral disk and wall is here reduced to a minimum, which renders the separation of
detached single septa more difficult. The parietobasilar muscle is moderately strong in
most septa, and does not even extend up to the third of the height of the animal ; it is
not merely connected with the septum by epithelial adhesion, but by coalescence, as the
supporting lamellae of both parts are fused to a great extent. The epithelial lamella? and
the muscular fibres of the surfaces of the parietobasilar fold and the septum which are
turned towards one another still remain, however, here and there between the fused
streaks of the supporting lamella?, and in transverse section originate circular figures
which are enclosed in the connective substance, and indicate by their serial arrangement
the boundary between the septum and the fold.

Two kinds of stomata are found in the muscular part of the septa ; the peristomial
are very large, whilst the marginal, which lie close to the wall, are small, and, in fact, so
small in the oldest septa that they are almost entirely obliterated.

The thin-membraned ved-like part of the septum is only furnished with a weak layer
of muscles, and bears both the mesenteric filament, which is fastened to its free margin,
and the reproductive elements, which in Dysactis are not rolled up into compact masses
as they are in most Actinia?. The follicles of the testes in the male, the ova in the
female are scattered over the supporting lamella, which, consequently, has the look of
being strewed with isolated star-like points. The filamental apparatus appeared to be
present in the ova.

A remarkable diversity usually prevails in the development of the septa. The
directive septa are very small, but, on the other hand, they are connected to a great
extent with the oesophagus, as the latter, in correspondence with them, is produced
into the long oesophageal lappets, which reach nearly to the pedal disk. The thin-
membraned part is small ; all the muscles, especially the parietobasdar muscle, stronger
than on any other septa ; reproductive organs wanting throughout. The directive septa
agree in the last respect with the other principal septa, and also with the six pairs of
septa of the second order, which are chiefly distinguishable from the principal septa by
not extending so far on the oesophagus. We first find the reproductive elements richly
developed on the twelve pairs of septa of the third order ; they are present on all other
septa, with the exception of the unimportant rudiments of those of the sixth order ; on
the other hand, the muscular parts of the septa become almost imperceptible, and they
themselves no longer project so distinctly into the gastric space. Only the septa of
the third and fourth orders stdl reach the oesophagus, though their insertion occupies no
great space ; the septa of the fifth order end on the oral disk.

It is remarkable that from the third cycle of septa onwards, the septa of one and the

REPORT ON THE ACTINIARIA. 49

same pair are never of the same size, so that for example half of the septa of the fifth cycle
are inserted at a considerable distance on the oral disk, whilst the other half run only to
two-thirds of the height of the wall. Closer investigation shows that this difference of
size is governed by fixed laws. From the moment when the septa of the first two cycles are
developed onwards, we find that after these all the interseptal spaces are bounded by septa
of different grades, i.e., by a septum of a higher and a septum of a lower order. The pro-
pinquity of the former causes a stronger development, e.g., in the newly-formed pairs of the
third order, the septum turned towards the older pair is always stronger than the other.
In the following pair of the fourth order, the septum which adjoins the septum of the
third order is always the smaller. These differences cannot, of course, arise in the second
cycle, as the interseptal space lies between septa of the first order which are of equal value.
As Dysactis crassicornis is not found at any great depth, and was dredged up by the
Challenger at several places, the probability that the animal may have come under the
observation of former naturalists deserves special consideration. Let me draw attention
to two forms which are perhaps identical with it. In the Annals and Magazine of
Natural History, 1872 (series iv., vol. ix. p. 304), Kyle describes an Actinia which he
procured by means of the hooks on fishermen's deep-sea lines. Like the form under
discussion, this Actinia reminds us of Tealia crassicornis, but differs from it in having a
smooth body surface which brings it nearer our Dysactis. The second Actinia is the Rho-
dactinia davisii, minutely described by Verrill (Mem. Boston Soc, vol. i. p. 18, 1866-69),
in which the papillae on the wall are so indistinct that the surface appears almost smooth.
The tentacles also appear to be similar, and, according to Verrill, are numerous, and
arranged in several indistinct rows ; they are conical or cylindrical, thick, rather short,
rounded obtusely at the end or even club-shaped. There is, however, some doubt about
this second form, as Verrill himself identifies it with Tealia crassicornis or rather Urticina
crassicornis, as he terms the species (Transactions Connecticut Acad., vol. i. p. 469).

Dysactis rhodora.

Actinia rhodora, Couthouy, in Dana,1 Explor. Exped., Zoopli., p. 118, pi. iv. fig. 37, 1846

(Synopsis, p. 11).
Dysactis rhodora, Milne-Edwards, Hist. des. Corall., torn. i. p. 2G3, 1857.

Tentacles tolerably long and slender, arranged in three rows ; the tentacles of the
inner row essentially longer and stronger than those of the middle and outer rows.

Habitat— Station 313. January 20, 1876. Lat. 52° 20' S., long. 68° 0' W. Depth
55 fathoms. Two strongly-contracted specimens.

1 The edition of Dana's chief work, Report on the Zoophytes of the U.S. Exploring Expedition, which appeared
in 1846, was very limited, and was soon out of print ; the author therefore subsequently (1859) published a
synopsis. I was only able to refer to the synopsis and the atlas, for the loan of which I am indebted to the kindness
of Prof. Ha;ckel. The quotations referring to the large work are taken from Milne-Edward's Histoire des Coralliaires
whilst I have myself looked over the synopsis and the atlas.

All the quotations have been verified in the Challenger Office by reference to the original work. — J. M.

(ZOOL. CHALL. EXP. — PART XV. — 1882.) p 7

5\) THE VOYAGE OF H.M.S. CHALLENGER.

Dimensions. — Pedal disk, 2-5 and 1*5 cm. ; height, 1"2 and 0'5 cm.

The two Actinia:, which I shall now briefly describe, belong to that class of specimens
in which the shape of the body has been so decidedly modified by the high grade of
contraction, and the colour is so completely gone from the action of the alcohol, that we
must observe very great caution in referring them to any species hitherto figured and de-
scribed. We must also bear in mind that in the case before us, even the larger specimen
under examination is not yet mature, and we must therefore consider that the structure
may undergo considerable changes in the course of growth.

The pedal disk and wall are tough-walled ; they seem to have been perfectly smooth
in a fresh condition, and only to have become irregularly wrinkled and pleated in con-
sequence of being preserved. The wall is thickened two or three-fold for a short
space at the upper end by the circular muscle. The latter is separated from the
endoderm by a narrow layer of connective substance, and greatly resembles in form the
circular muscle of Tealidivm cingulatum figured in Plate VI. fig. 2. Seen in transverse
section, it widens towards the upper end like a club, though not so strikingly ; towards
the lower end it runs out into a fine point, by which it nearly reaches the endoderm.
The bundles of fibrillae are formed of a few very strong fibrillae, which are apposed one to
the other in form of a ring in transverse section ; they are separated by a sparse layer of
interstitial substance, and are only indistinctly arranged in larger and smaller groups.
The smallest bundles are found towards the lower pointed end, where they often merely
consist of from three to four fibrillae.

The tentacles, whose number may be roughly estimated at about a hundred, are
placed in three circles, the innermost are the longest and decidedly the strongest ;
they measure more than 0-6 cm., even in the contracted animal, whilst the outermost
present very thin filaments only 0-3 cm. in length. I could not perceive any
terminal openings. The muscular system on the surface is a repeatedly folded layer
of ectodermal fibres, which also pass uniformly on to the oral disk. By this difference,
and also by the varying character of the circular muscle, Dysactis rhodora can be at
once distinguished from Dysactis crassicornis, in which the muscles of the oral disk and
the tentacles have passed into the mesoderm, whilst the circular muscle lies close under
the endoderm.

Any description of the oesophagus would be of little interest. I shall therefore pass this
over, and proceed at once to discuss briefly the septa, the regularity of whose arrange-
ment is remarkably clear in section. There are in all four orders ; the six pairs of
principal septa and the six pairs of secondary septa are perfect, and only distinguishable
from one another by the former being more muscular than the latter. The septa
of the third order are imperfect and essentially smaller, whilst the last septa are
narrow, thin lamella?. In the quadrant, used for investigation, the septa of a cycle

REPORT ON THE ACTINIARIA. 51

were of equal size throughout, and showed a very unusual regularity of development.
Directive septa are present, as I have proved from direet observation.

The longitudinal lamella is not very strong, but pleated in a large part of the septa.
The parietobasilar muscle reaches half-way up the wall ; it is partly fused with the
septum, partly laid on it in loose folds.

Finally, the two kinds of openings, already known in various other Actinia?, are
found in the perfect septa ; from their small size they might easily be overlooked, though
I have observed them in dissected septa, both seen from the surface and in transverse
section.

Tealidium, Hertwig.

Paractidae, having the tentacles placed in several rows and of uniform size in the
same row, and having the wall covered with fine papdlae.

As I limited the genus Tealia (see p. 34) to animals with an endodermal sphincter,
projecting in the form of a swelling into the stomach, it became necessary to form a new
genus, which I have named Tealidium, for all forms which agree with the Tealidse in the
papillose nature of the wall, but which differ from them in the mesodermal position of the
sphincter. I consider it of no importance whether the papilla? are regular or irregular,
compacted or scattered, or whether the wall is incrusted with foreign bodies or not. On
the other hand, I have included the uniform character of the tentacles in the diagnosis,
for I regard Tealidium as a genus parallel to Paractis, which it resembles except in one
distinguishing point, viz., the warty nature of the body surface.

Tealidium cingulatum, Hertwig (PI. III. fig. 3 ; PI. VI. fig. 2 ; PI. VIII. figs. 7, 8).

Tentacles small, placed in two rows ; the mesodermal circular muscle projecting as a
circular swelling from the outer surface of the wall ; the wall covered with numerous lonoi-
tudinaJ furrows, corresponding to the origins of the septa.

Habitat— Station 158. March 7, 1874. Lat. 50° 1' S., long. 123° 4' E. Depth,
1800 fathoms. One specimen.

Colour. — (Determined from the spirit specimen) pale saffron yellow.

Dimension*. — Diameter of the pedal disk, 1 cm.; height, a few millimetres.

The single specimen of Tealidium cingulatum,, which was taken attached to a stone
from a depth of 1800 fathoms, belongs to the smallest forms among the Challenger
material. It is so strongly contracted that the wall closes over the entrance to the oral
disk till only a small opening is left. I could therefore neither determine the extent of the
oral disk nor the height of the body, and the only means of determining its size was the
diameter of the pedal disk, which amounted to about 1 cm. The colour of the body, if it
has not been changed by the influence of the alcohol, is a delicate saffron-yellow.

Twenty-seven sharply-defined longitudinal furrows can be counted on the wall; they

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

begin at a little distance from the margin of the pedal disk, become less distinct as they
run upwards, and disappear towards the margin of the peristome. Besides the furrows
the body is covered with numerous small papillae, which can only be distinctly recog-
nised with the magnifying glass, and which show a pattern like shagreen on the wall, as
they are all of the same size and closely compacted. The entrance to the oral disk is
surrounded by a circular swelling projecting above the surface, which belongs to the
upper end of the wall ; a shallow circular furrow runs near the lower end at a short
distance from the margin of the pedal disk.

Nothing further could be observed in the uninjured animal, and on account of its
smallness and strong contraction no further results could be expected from a dissection
with scissors and knife. I therefore cut out a piece about the size of a quadrant, in which
I examined the circular muscle, the oral disk, the tentacles, the oesophagus, and the septa
in transverse sections, changing the plane of the section as occasion required.

The circular muscle, which lies in the mesoderm, is so powerful in Tealidium that the
bulk of it has not room enough in the thickness of the wall. Just as a purely endodermal
circular muscle causes a circular swelling on the inside, so this strong mesodermal muscle
causes a similar swelling on the outside, as the surface of the wall is arched out to
nearly four times the usual thickness ; it can be recognised by simply looking at the
animal, and has already been briefly mentioned. It probably becomes still more apparent
when the Tealidium is extended, and then produces a girdle under the origins of the
tentacles, on account of which I have named the form Tealidium cingulatum (PI. VI. fig. 2).
The entire mass of the muscle is club-shaped in transverse section. The smaller end,
which is turned downwards, runs out into a fine point, which extends nearly to the endo-
derm, through the broad intermediate layer of connective substance.

The separate muscular fibres are fine, and so are the primitive bundles formed by
them ; from the manner in which the latter are grouped, it seems probable that they arise
from division of larger bundles, of which a few still remain (PI. VIII. fig. 8). The
process of division seems to go on very rapidly in the peripheral parts, as we there find
not only groups of two, three, and four fibrillar enclosed in the fibrous connective
substance, but very frequently completely isolated single fibrillse (PI. VIII. fig. 7).

There was nothing remarkable about the oral disk and the tentacles ; their radial
longitudinal muscular fibres are ectodermal, and extend in an almost smooth layer, which
is only distinctly pleated at the bases of the tentacles. The number of the tentacles
which are distributed in two circles amounts to twenty-four ; they are of no great length,
so that they are completely hidden under the contracting circular muscle.

The number of the septa in the quadrant examined amounted to seven ; as they usually
correspond to the longitudinal furrows already mentioned, their number in the entire
animal must be reckoned at more than twenty. Their paired arrangement is shown by the
course of the muscles ; two directive septa were present in the quadrant, so that there is no

REPOKT ON THE ACTINIARIA. 53

reason why we should not regard the animal as conforming to the common plan of the
Actinias. The result would therefore be that the animal has altogether two cycles or
twelve pairs of septa. All the pairs of septa are quite uniform, all reach the stomach, and
all bear reproductive organs. In the case before us, the latter are mature testes,
closely filled with separate follicles of spermatozoa. As usual the tails of the spermatozoa
lie inwards, the heads outwards, the former converge at the same time towards a point in
the surface where the follicle projects into the epithelium, and where it probably bursts
later on, in order to empty out its contents.

Antholoba, Hertwig.
Metridium, Milne-Ed wards, pro parte. Hist, des Corall., torn. i. p. 252.

Paractidse with innumerable small tentacles, which lie on a swollen thickening of the
mararin of the disk ; margin of the disk lobed as in Metridium.

After Oken had erected the genus Metridium for the beautiful Actinia Plumosa s.
d in it tli us (Lehrbuch d. Naturgeschichte, Th. III. Abth. 1, p. 349, 1815), Milne-Edwards
included in it all the forms which agreed with the typical representatives in the peculiar
arranp-eruent of the tentacles and in the beautiful wave-like form of the lobes which border
the oral disk. The probability that animals which resemble each other externally may
differ essentially in their internal organisation was quite overlooked.

This is, in fact, the case, as I have proved from my own observation. It is quite
correct to place Metridium dianthus among the Sagartidse, since, in it as in them, only the
six pairs of principal septa reach the oesophagus, and, according to Gosse (Actinologia
Britannica, p. 20), are also furnished with acontia. Metridium dianthus differs in both
these points from an Actinia, which was first observed by Dana, and was erroneously added
to the genus Metridium by Milne-Edwards (Histoire des Coralliaires, torn. i. p. 253) and
Verrill (Trans. Connect. Acad., vol. i. p. 479). In this Actinia the acontia are wanting,
and the septa for the most part perfect as in the Paractidse. Other conditions, such as
the presence of a mesodermal sphincter, also show that this Actinia is a true Paractid. I
therefore propose to form the new genus Antholoba for these forms which externally
recall Metridium, but which, on the other hand, have no acontia, and are furnished with
numerous perfect septa as well as with a mesodermal sphincter.

Antholoba reticulata (PI. I. fig. 9 ; PI. X. figs. 11, 12 ; PL XIII. fig. 9).

Actinia reticulata, Couthouy, in Dana, Explor. Exped. Zoopk, p. 144, pi. iv. fig. 31, 1846 (Synopsis,

p. 10).
Metridium reticulatum, Milne-Edwards, Hist, des Corall., torn. i. p. 255, 1857.
Actinoloba reticulata, Gosse, Actinologia Britannica, p. 24, 1860.
Metridium reticulatum, Verrill, Trans. Connecticut Acad., vol. i. p. 479, 1871.

Margin of the disk fivedobed, with several thousand small tentacles, the twelve ten-
tacles of the first and second cycles larger than the others, and placed towards the centre at a

;,4 THE VOYAGE OF II.M.S. CHALLENGER.

little distance from them ; the thirty-six following still easily recognisable ; the wall tra-
versed by reticulated furrows ; mesodermal muscle developed throughout the entire length
of the wall.

Babitat.— Station 313. January 20, 1876. Lat. 52° 20' S., long. 68° 0' W. Depth,
55 fathoms. Three specimens.

Dimensions. — Diameter of the oral disk, 3"5-6"0 cm. ; height of the body column,
2-0-2-5 cm.

The three specimens of Antholoba reticulata included in the Challenger material were
admirably adapted for examination, as the body was only slightly contracted. This
applied especially to the largest specimen, which was 6 cm. broad and 2-5 cm. in height,
and upon which the following observations have been principally made.

The pedal disk is very thin walled, so that the insertions of the septa shine through it
as innumerable clear lines ; the margin is indistinctly lobed, probably five-lobed like the
margin of the oral disk. The firm compact wall of the Actinia rises in a curve at an
acute angle from the pedal disk, and is constricted more or less distinctly at a third
of its height. The lower part of the wall is traversed by circular furrows, which are
perhaps merely caused by the contraction of the muscles of the body, its upper part is
covered with soft papillae, about 0 -5-1-5 mm. broad, which are not sharply separated,
lie close together, and are very much flattened. Shallow furrows, which give the surface
of the body its reticulate appearance, and which Couthouy had in view in naming the
species, remain between the papilla?.

The mesodermal circular muscle is never very strong, but, on the other hand, it extends
from the upper to the lower end of the wall, a formation which I have never found in any
other Actinia. In longitudinal section it can be distinguished by the naked eye as a
yellowish layer, situated close under the endoderm, which is 0"5 mm. broad in its upper
third, but diminishes as it runs downward (PI. XIII. fig. 9). Its bundles of fibrilhe (PL X.
fig. 11) are all very small but thickly compacted, and only separated by a little con-
nective substance ; they are all strongly flattened in the same direction in such a way that
their edges lie perpendicular to the endodermal epithelium. They have an inclination to
lie one behind the other in rows, which run outwards from the epithelium, and in this way
they have the appearance of being produced by the breaking up of long thin muscular
plates. The large bundles of fibrillar are found on the outside, but the smaller ones inside,
close under the endodermal layer of circular fibres, which is repeatedly pleated over
them. From all this it seems probable that small bundles of fibrillar are continuously
detached by pleating from the endodermal layer, and are transformed by growth into
larger bundles in the depth of the layer.

At the upper end the wall passes gradually into the oral disk, the margin of which is
swollen like a pad. The limits of the disk are indicated by the appearance of the ten-
tacles and the disappearance of the circular muscle.

REPORT ON THE ACTINIA RI A. 55

The oral disk is five-lobed, its periphery being delicately sinuated ; its upper third is
so thickly strewn with small tentacles that it is impossible to determine their number,
though we may estimate them at from two to three thousand; they are all very slender,
thin-walled, and caeca! ; they are largest towards the centre of the disk, and become
smaller towards the periphery. Twelve tentacles, which are particularly conspicuous
from their size, lie somewhat apart from the rest, nearer the centre of the oral disk, so
that they are isolated from the others. They are distributed at ecpaal distances round
the oral fissure in such a way that two of them correspond to the corners of the mouth ;
this mode of distribution leads us to conclude that they belong to the intraseptal spaces
of the six pairs of principal septa and the first six pairs of accessory septa. Outside these
come thirty-six other tentacles, which make up a circle ; twelve of these alternate
with the first twelve, the other twenty-four falling between the latter and the former.
The thirty-six tentacles can hardly be defined from the peripheral principal mass, because,
in the first place, there is hardly any interspace between them, and, in the second place,
because they are but slightly superior in size. They belong to the tertiary and quaternary
intraseptal spaces. By dissecting the septa, the peripheral mass of small tentacles may
also undergo examination, the result of which is to show that they all lie in different
radii of the body. We never find more than one tentacle in communication with the
same intraseptal space, though such a result seems highly probable on mere superficial
examination. All the tentacles belong primarily to a single circle, and have only been
forced into different circles by want of space.

The radial muscular system, which in this case also lies in the mesoderm, shows the
same characters as those which we have already observed in the circular muscle. The
mesoderm is pleated in transverse section, and, in well preserved animals at least, is
covered with a layer of radial fibres ; the mesodermal bundles of fibrillse are flattened
and placed in rows which begin in the pleating on the surface of the mesoderm and run
straight towards the inside. We may say that we have before us deep laterally com-
pressed folds, which fall asunder into numerous bundles of fibrillse placed one below the
other (PL X. fig. 12).

The layer of muscle is strongest between two septal insertions, and the mesoderm
consequently slightly thickened. In this way radial swellings are formed on the oral
disk, which, however, become more perceptible in transverse section than when looked at
from the surface of the oral disk, and more perceptible near the tentacles than in the
periphery of the mouth.

The oral opening rises slightly like a proboscis above the surface of the oral disk, and
forms an oval fissure, one end of which is directed towards one of the points where the
margin of the oral disk arches inwards, and the other end to a point where it arches
outwards. The two oesophageal grooves are remarkably distinct on the oesophagus, as
they are enclosed by high lips, which project like combs, corresponding to which the

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

oesophageal lappets extend downwards, far into the stomach. The upper half of the
oesophagus shows about twenty longitudinal ridges which are prolonged lower down into
a larger number of smaller ridges. The boundary between the oral disk and the
oesophagus is defined by a sharp line.

The septa (PI. XIII. fig. 9) are very simple in construction, as specially differentiated
muscles (retractor and parietobasilar muscle) are wanting, and the two primitive layers of
muscles only are present. Transverse muscles, which run oblkmely between the wall on
the one hand and the oral disk, oesophagus, and free margin of the septa on the other,
extend on one side, and are strongest in the upper and lower third, where their lamellae
are repeatedly folded ; on the other side run parallel longitudinal muscles also in a
repeatedly folded layer from the pedal disk to the oral disk and the oesophagus. In the
perfect septa a small peristomial opening lies hidden in the angle formed by the junction of
the proboscis-like part of the oral disk with the oesophagus.

As may be concluded from the large number of the tentacles, the number of the septa
is something quite unusual, even though many of them have stopped growing at a very
early stage. The septa of the second and third cycles are perfect as well as the principal
septa, and are easily distinguished from one another by the difference in size and by
the extent to which they descend on the oesophagus. Of the imperfect septa, those belong-
ing to the fourth and fifth orders are still well developed ; after that they decrease rapidly in
size, so that the other septa almost come to be mere folds projecting more or less in the
angles on the upper and lower end of the wall. This recalls the comportment of the
tentacles in which the first four to five cycles are the most easily distinguished.

In order to obtain a general idea of the aggregate number of the septa, I prepared an
intraseptal space of the third order as completely as possible, and made a transverse section
through it, which passed through the upper part of the wall and the peripheral part of the
oral disk. In this section I found more than sixty separate septa. This would give over
1500 septa, or over 700 pairs of septa for the entire animal. There appear, therefore, on
the whole, to be eight cycles or 768 pairs of septa. There may perhaps be traces of a ninth
cycle, as each interseptal space of the eighth order is furnished with at least three tentacles.

I can say nothing as to the distribution of the reproductive elements on the septa, as
their thin-membraned parts had stuck together and were badly preserved. Some figures
which I got in the sections lead me to believe that Antholoba may possibly be herma-
phrodite. This would be very unusal, as I have as yet only observed herm aphroditism in
Gerianthus and Scytoijhorus.

Ophiodiscus, n. gen.

Paractidae with a single corona of long tentacles, which project at the margin of the
wall and oral disk, and are only furnished with muscles on the upper side ; wall smooth,
with longitudinal furrows, indicating the insertions of the septa ; septa differentiated

REPORT ON THE ACTINIARIA. 57

into muscular septa and reproductive septa. The animals do not appear to draw the
oral disk over the mouth, though a mesodermal muscle is present.

The external appearance of the Actiniae, for which I have formed the new genus
Ophiodiscus, recalls that of Anthea cereus, as the tentacles are of great length, project in a
single row on the outer margin of the oral disk, where it is turned over into the wall, and
hang down like flowing hair over the side walls of the body. The margin of the wall was
also not drawn over the oral disk as in the Paractidse. It would, however, be rash to
conclude from the form presented by the animals before me that they are quite incapable
of concealing the oral disk, and the more so as I succeeded in finding a mesodermal
sphincter. It is possible, however, that, considering the size of the body, the sphincter is
not very strongly developed, so that the contraction caused by it is a slow process.

A further point which distinguishes Ophiodiscus from the other Paractidse is the
constitution of the tentacles. As one wall of the tentacles is formed by the prolongation
of the body wall, the other by the prolongation of the oral disk, they show the same
differences in the distribution of the muscles which characterise the said sections of the
body wall. The former only has longitudinal muscles, the latter is without muscles and
is correspondingly thinner walled.

The differentiation of the septa into sterile septa with muscles and reproductive septa
with weak muscles is still more important. The latter are extremely rudimentary, and
have even lost the mesenteric filaments ; whilst in other Actinias a distinct graduation in
size prevails in the separate cycles of septa, there is a pronounced distinction between the
smallest muscular septa and the reproductive septa. It may be advisable at some future
time to erect this form into a special family.

Ophiodiscus annulatus, n. sp. (PL X. figs. 1-10).

Wall surrounded close below the tentacles by numerous circular furrows, caused by
the sphincter, which become less distinct towards the lower part of the wall.

Habitat. — Station 299. December 14, 1S75. Lat. 33° 31' S., long. 74° 43' W.
Depth, 2160 fathoms. Four specimens.

Dimensions. — Height, 0-5-l"8 cm. ; breadth of the oral disk, 2"0-4'5 cm.; breadth of
the pedal disk, TO-3'5 cm.

Before proceeding to describe Ophiodiscus annulatus, I wish to make a few preliminary
remarks as to the state of preservation in which I found the animals in question. It was
unfortunately extremely unsatisfactory, which I regret the more as they are a particularly
interesting form. In all the specimens the tentacles were tattered and frayed out at
the end, and there were rents here and there in the wall between the insertions of the
septa. The largest specimen was so much destroyed that I could not take any measurements
from it. All this must be ascribed to the fact that the animals came from a great depth,
and had been injured in hauling up the dredging apparatus. The animals have, moreover,

(ZOOL. CHALL. EXP. — PART XV. 1882.) P 8

5$ TILE VOYAGE OF H.M.S. CHALLENGER.

suffered from having been pressed closely one against the other in the same bottle,
so that they are flattened, and the relief of the body surface rendered indistinct. The
dimensions given above and the following description of the form of the body are therefore
merely of hypothetic value ; the unfavourable state of preservation also explains why I
have omitted to give exact numbers in describing the different parts of the body.

The height of the body in the living animal seems to have been small, its breadth
essentially greater in the region of the oral disk than at the base, so that the whole form
of the body may be termed " dish-shaped." It is divided into an upper broader and a
lower narrower section by a deep circular constriction. Nearly one hundred tentacles,
probably of astonishing length, hang down from the margin of the oral disk. In the
smallest specimen there was still one tentacle which extended into a thin filament, 8 cm.
long. I grant that this measurement may have resulted from the tentacle having been
forcibly stretched, but considering that the diameter of the animal itself only amounts to
l'O cm., we may safely assume that the length of the tentacles exceeds the former several
times. This is also perhaps the reason why the tentacles are nearly all torn away.
Whether the tentacles of each different order are of equal size or not, can only be deter-
mined by examination of other specimens.

The surface of the wall (fig. 1) is marked by about one hundred longitudinal furrows,
which lie at ecpial distances from one another, correspond to the origins of the septa,
and pass as radial streaks on to the pedal disk. Besides these longitudinal furrows,
horizontal furrows run in the upper fourth close under the corona of tentacles, parallel
to the margin of the oral disk ; the swellings between the circular furrows are broadest
above, whilst they become narrower and flatter below. The swellings and furrows
are more pronounced on the endodermal side than on the ectodermal ; at the same time
wTe see in longitudinal section (fig. 6), that the internal furrows correspond to the external
swellings and vice versa, so that the wall is pleated transversely. Its substance is, more-
over, partially thickened, and it is on account of these partial thickenings that the swell-
ings project more towards the inside than towards the outside.

The thickening and pleating of the wall are caused by the mesodermal circular muscle,
whose bundles of fibrillse are arranged close under the endoderm in layers, which run
parallel to the surface and follow all its pleatings. There are from nine to ten such
layers inside the uppermost and broadest swelling (fig. 6, a) ; they gradually decrease in
number, in the middle (fig. 6, fi) there are only about four, and later (fig. 6, 7) only two,
till finally the circular muscle extends a little way in the now flat part of the wall as
a single layer of small bundles which continue to become more sparse (fig. 6, S). The
separate muscular fibrillas are remarkably thick, whilst the bundles formed by them are
small, and as usual compressed in the direction of the longitudinal axis of the animal.
The smallest bundles lie immediately below the epithelium, from which they appear to
be formed, as shown in figs. 7, a, /3.

REPORT ON THE ACTINIARIA. 59

The surface of the oral disk is smooth, or only indistinctly furrowed radially ; if ex-
amined in transverse section (fig. 5) it shows a set of strong mesodermal muscles, a broad
band, separated both from the endoderm and the ectoderm by a layer of supporting
substance. This band is broken by a separating bar of connecting substance, correspond-
ing to the insertion of every septum. It is further a law of its development that the
supporting substance grows out strongly into the muscular baud from the endodermal and
ectodermal sides alternately, and forms ridges from which ramified supporting layers
stretch towards the opposite side. In this way smaller and larger elongated compartments
are formed, which are filled with muscular fibres. These muscular fibres, like those of the
wall, are extremely thick, and the manner in which they pass on to the tentacles dis-
tinguishes the Ophiodisci sharply from other Actiniae.

Althouoh the tentacles were badly preserved, it was perfectly clear that they are thin-
membraned on one side but thickened on the other (fig. 2). This thickening is caused
by a muscular cord which can be followed even with the naked eye as a broad fibrous
streak running from the oral disk to the tentacle. It occupies that side of the tentacle
which is turned upwards in a state of rest, and projects at its base right and left a little
above the surface. It thus forms two wing-like expansions which pass a little way on to
the oral disk. The structure of this cord is the same as that of the muscular band of
the oral disk ; it is composed of strong, thickly compacted muscular fibres, divided by thin
layers of connective substance into compartments of muscular fibres.

Muscular fibres are wanting in the thin membraned parts of the tentacles, unless
they be present in the ectoderm, which could not be determined, as the ectoderm was
completely macerated away. Whilst the muscular cord passes into the oral disk, the thin
membraned parts of the tentacles, on the other hand, are prolongations of the wall. This
is brought about by the fact that the tentacles lie exactly on the border line at which
wall and oral disk are united.

Before passing into the oesophagus, the oral disk is raised in the periphery of the
mouth into a proboscis-like projecting lip. The proboscis is marked on either side with
about ten longitudinal furrows, and is likewise furnished with two oesophageal grooves,
which are enclosed by two strong longitudinal folds, hard as cartilage, and pass downwards
on to the long oesophageal lappets. In one specimen the lower part of the oesophageal
grooves appeared closed into a tube by fusion of the margins of the folds.

The number of the septa amounted in all to forty-eight pairs, which are distributed in
four cycles. The first three cycles, that is, the first twenty-four pairs, are formed exclu-
sively of muscular septa which do not bear reproductive organs ; of these the septa of
the first two cycles only reach the oesophagus, the remaining twelve pairs are imperfect.
Septal stomata are wanting. The muscles are slightly developed, for I could not even find a
parietobasilar muscle. In consequence of insufficient preservation, the free margins of the
septa had become frayed out, and only part of the mesenteric filaments remained (fig. 4).

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

In contrast to the sterile muscular septa, it is the last twenty-four pairs of septa which
alone bear the reproductive organs (fig. 4, g), but, on the other hand, have neither muscles
nor mesenteric filaments ; they have, moreover, undergone retrograde formation, for they
merely project as small folds in the angle between the wall and the pedal disk, and only
extend up the wall as far as the circular constriction described above. We can distinguish
two parts on each septum, the free margin, which is thickened by the layers of reproductive
elements and much folded, and a thin veil-like membranous part which, like a mesentery,
fastens the reproductive organ to the pedal disk and wall.

The septa of a reproductive pair are always unequal in size, and that one of them is
always the largest which stands next the muscular septum of the higher order.

Enveloped in the same bit of cloth as the four specimens of Ophiodiscus, there was
a peculiar, dendritically branched body, which may possibly have belonged to one of the
animals as an appendage of the wall from which it had been torn away ; I shall therefore
give a supplementary description of it.

The pseudo-tentacle — as I shall term it in what follows, though I do not wish to settle
its signification — is a very dainty, delicately- walled formation (fig. 8) ; a short basal stem
is almost immediately divided into numerous branches, and these, undergoing repeated
dichotomy, finally form a terminal bush of club-like twigs. The principal branches fre-
quently anastomose, so that it is difficult to subdivide the brush of tentacles according to
its principal ramifications, which, moreover, form here and there small vesicular swellings.

By the help of weak magnifying power we can make out accurately the nature of the
ramification and the form of the twigs (fig. 9). Each new branch is separated from the
preceding by a circular constriction, and begins and ends with a small swelling. One of
the twigs formed by dichotomy is usually behind hand in becoming branched, and this is
specially apparent at the ends. These present three points, as one of the twigs caused by
the last bifurcation only is redivided, whilst the other remains simple.

Like the tentacles, the pseudo-tentacle contains a hollow space, which is without doubt
an evagination of the gastrovascular system ; we can also distinguish three layers, an inner
layer, probably endodermal, an outer, ectodermal, and the intermediate supporting lamella.
Within the latter small fusiform cells are enclosed in a perfectly homogenous fundamental
substance (fig. 10). Strong, circular muscular fibres run in the ectoderm; seen from the
surface these caused an annulation of the branches which becomes less distinct at the ends.
Transverse and longitudinal sections are necessary in order to make out the position of
these fibres. In these sections I also observed fine fibres on the endodermal side ; they
were arranged longitudinally, and consequently crossed the course of the others. They
also seemed to be of a muscular nature.

The epithelial layers were badly preserved, the ectodermal layer all but wanting, and
the endodermal merely showed a thin layer of protoplasm wfith scattered nuclei.

What grounds have we for assuming that the structure described above is a com-

REPORT ON THE ACTTNIARIA. 61

ponent part of an Ophiodiscus f From the structure of the organ we may assume one
thing, that it belongs to a Ccolcnterate, as it shows the three body layers which charac-
fcerise these animals ; the presence of cells in the supporting lamella makes it still more
probable that it belongs to an Actinia. There is therefore nothing in the structure
which goes against this view, but what is greatly in favour of it is the fact that the
pseudo-tentacle and the Actinia were found in the same envelope, not accidentally, but
because they belong to one another.

In fact there are descriptions published of Actiniae which bear richly branched bush-
shaped appendages as well as tentacles. Such, for example, is Lebrunia, found by
Duchassaing and Michelotti in the Antilles (Memoire sur les Coralliaires des Antilles,
Memorie della R. Accademia cli Torino, ser. ii. t. xix. p. 324, pi. vii. fig. 8). The only
species of the genus, Lebrunia neglecta, bears outside the corona of long simple tentacles
five composite tentacles, which spring from the wall, and dichotomise till they run out into
numerous terminal branches. The general habit of body of the four Actinias examined by
me also recalled Lebrunia, inasmuch, as appears from Duchassaing's plates, the tentacles
also spring from the outermost margin of the disk and hang down like hair over the wall.

I endeavoured to find remains of pseudo-tentacular appendages on the walls of the four
specimens, but my attempts were unsuccessful, which is not to be wondered at considering
the injuries which the animals have suffered, and that if these occasioned the loss of the
stronger tentacles, it is likely that the very delicate pseudo-tentacles have been completely
destroyed. Whether Ophiodiscus be related to Lebrunia, and might even be placed with
it in a common genus, or whether they have absolutely nothing in common, remains
therefore an open question. If the drawing given by Duchassaing of the branched pseudo-
tentacles be true to nature, they differ so widely from the pseudo-tentacle described above,
that it would be advisable at least to separate the species.

Ophiodiscus sulcatum, n. sp. (PI. III. fig. 8).

Wall smooth ; oral disk covered with numerous radial, deeply sunk furrows ; body
discoid.

Habitat.— Station 300. December 17, 1875. Lat. 33° 42' S., long. 78° IS' W.
Depth, 1375 fathoms. One specimen.

Dimensions. — Diameter of the oral disk, 9 cm.

In fig. 8 of Plate III. I have endeavoured to reconstruct an Actinia, which was
so completely tattered that a superficial examination could hardly recognise an Actinia in
the whitish mass. I succeeded by careful apposition of the parts in restoring the whole of
one half and the greater part of the other half ; I also discovered the oesophageal grooves,
and in this way, determined the sagittal plane, so that I bebeve the drawing accurately
reproduces the essential points of the animal's habit of body. In preparing the drawing
I copied the one half, extending from one oesophageal groove to the other, as accurately

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

as possible, and filled up the other half which was still more torn. I have only given
the bases of the tentacles, as they were either only preserved in short pieces or were torn
away close to the body of the animal.

The pedal disk is much smaller than the oral disk, and is covered with numerous
radial ridges, somewhat in the same way as in Polysiphonia tuberosa (PL IX. fig. 5).
The wall is smooth and tolerably thick-walled ; its upper part contains a mesodermal
circular muscle, which is very weak in proportion to the size of the animal, both in extent
and in the number of its bundles of fibrdlse and the strength of the single fibres. On
the other hand, powerful masses of muscle are accumulated in the oral disk. The latter is
covered with deeply sunk furrows, which begin between the bases of the tentacles and run
in a radial direction towards the oral opening. The furrows end in the periphery of the
mouth, which is somewhat swollen, and at which two adjacent furrows are sometimes
united. The swellings between the furrows, which are sometimes narrow sometimes
broad, are caused by the deposition of strong mesodermal muscles. Their structure
resembles that already described in Ophiodiscus annulatus, except that the bundles of
fibrillse are much more numerous, and form a layer which is at least twice as strong.
The number of the radial swellings in the well-preserved half amounts to twenty-four,
therefore to forty-eight in all.

There are likewise forty-eight tentacles which spring exactly from the junction of the
wall and the oral disk, one of their walls representing a prolongation of the former, the
other a prolongation of the latter. The thick muscular cords therefore only pass on to
one side of the tentacle walls, whilst the other consists merely of supporting substance.

Though only a few of the septa were preserved, these were sufficient to show that
they are distributed in alternate pairs of muscular and genital septa. The genital septa
are thin-walled, whilst the muscular are strengthened by a thick supporting lamella. As
there are in all forty-eight tentacles, the number of the muscular septa also amounts to
forty-eight or twenty-four pairs.

The above statement suffices to prove that Ophiodiscus sidcatus is very closely allied
to Ophiodiscus annulatus, but distinguished from it by the absence of annulation of the
wall and by the strong formation of furrows in the oral disk. The two forms may even
represent one and the same species, and the differences merely arise from difference of age.
At any rate they were both taken at a great depth in two localities, geographically not far
apart.

It is also well worthy of our consideration that in no other Actinia did I find the
tentacles so shattered as in the two species before me, not even in specimens dredged
from still greater depths. This may perhaps have to do with the fact that the animals
attach themselves to foreign bodies by their muscular tentacles. I have already specially
remarked that the tentacles are probably of great length in the living animal, so that they
would be especially adapted for holding on to other objects.

RETORT ON THE ACTINIARIA. 63

Liponemid^e, Hertwig.

Hexactiniae with numerous perfect septa and with marginal tentacles transformed by
rctrogade formation into short tubes or into stomidia,

Anions the Actiniae of the Challenger material there were some forms in which the
tentacles had undergone a greater or less degree of retrograde formation. One part of
these, i.e., all the true hexamerous Actiniae, I have united in the family of the Liponemidae.
I shall discuss the others afterwards in the tribe of the Paractiniae, as they are distinguished
from the Liponemidae by the principle of arrangement of the septa, and I attach more
importance to this characteristic than even to the peculiar constitution of the tentacles.

If this retrograde formation of the tentacles is therefore to be regarded as a process
which is carried on repeatedly and independently, the cpiestion may justly be raised if it
would not be advisable to distribute the Actiniae without tentacles among the other families.
In this case the genus Polysiphonia ought to be placed among the Paractidae, the genus
Pohjstomidium among the Antheadae, as the former has a mesodermal circular muscle,
and the latter a weak endodermal circular muscle.

Polysiphonia. n. gen.

Liponemidae with tentacles, transformed by retrograde formation into short tubes
with wide terminal mouths ; circular muscle mesodermal, slightly developed.

In the genus Polysvphonia we find the first stage of the retrograde formation
of the tentacles ; they have become short, stiff-walled tubes, which have only a
weak set of muscles, are, at any rate, only capable of a small amount of contraction, and
are therefore of no great value, either for groping about or for seizing upon prey. But as
the terminal opening is very much enlarged and appears to remain permanently open,
they have become inhaling tubes, through which the animal can draw in water and
the nourishment suspended in it.

Pohjsiphonia tuberosa, n. sp. (PI. II. figs. 7-9 ; PI. VI. fig. 3 ; PI. IX. figs. 1-10).

Body stiff and thick-walled, shaped like a stemless chalice, the surface beset with
roundish knobs ; oral disk, twelve lobed; tentacle tubes thickened to a swelling at the base,
of different sizes, placed in two alternating rows ; the larger tentacles correspond to the
archings inwards, the smaller to the archings outwards of the oral disk.

Habitat— Station 235. June 4, 1875. Lat. 34° 7' N., long. 138° 0' E. Depth, 565
fathoms. Twenty specimens.

Dimensions. — 'Diameter of the pedal disk, 3-4 cm. ; diameter of the oral disk, 8-10
cm. ; height, 5-8 cm.

Numerous specimens of a beautiful large Actinia, Pohjsiphonia tuberosa, were all
dredged on the same spot from the bottom of the sea, at a depth of 565 fathoms. To
judge from the nature of the material, part of them had been placed at once in spirit, part

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

previously treated with chromic acid. The former were unfortunately of absolutely no
use, their tissues were macerated, and the form of the body disfigured by pressure almost
past recognition, whilst the latter permitted a detaUed description of the body form and
of many anatomical conditions ; the septa had, however, suffered severely in preservation,
which, as I have noticed, is usually the case in material prepared by means of chromic acid.

Making allowance for changes caused by pressure, the form (PI. II. fig. 7) is the same
in all the specimens. The body begins with a relatively small, firmly attached base, rises
to a considerable height, and gradually expands like a stemless chalice up to the oral disk,
which unfolds like a flower. This form is rare among the Actiniae, especially in con-
tracted animals, since, on the other hand, the inversion of the margins of the oral disk
usually causes the body to diminish in size upwards like a cone.

The ectodermal side of the pedal disk (PL IX. fig. 5) is covered with numerous (more
than a hundred) radial ridges, which begin at the margin, and, partly at least, extend as
far as the centre. They form a very dainty figure, as they have a vandyked, wavy course,
and project with unusual sharpness above the level of the disk. On the endodermal side
there are strong muscular cords, piercing the bases of the septa in bundles (fig. 4) ; they
are crossed by other muscular cords, which pass transversely through the pedal disk from
the endodermal to the ectodermal side. These perforating muscular fibres originate from
the two muscular layers of the septa ; this is best shown in transverse sections taken per-
pendicularly to the direction of the septa (fig. l). Some of the longitudinal and of the
transverse fibrdlae diverge and reach the mesoderm in bundles ; their fibrillae become inter-
mixed, as they become interwoven with one another and with the layer of the basal circular
muscles. The bundles then run towards the depressions which separate the ridges on the
ectodermal side, and become fastened at the bottom of them ; here they split up into the
fibrillae of which they are composed (fig. 7), so that their ends appear to be dendritically
branched, and remind us of the ends of the muscular fibres of the Ctenophora.

As the perforating bundles originate from the muscles of the septa, it naturally follows
that they are arranged regularly in radial rows. Each septum has two hardly separate
corresponding rows, one of which is derived principally from the transverse muscles,
the other principally from the longitudinal muscles. This is seen in the section which I
have given in fig. 3, and which was taken parallel to the boundary surfaces of the pedal
disk. As the section has fallen somewhat obliquely, we see at one end the bases of the septa
cut through obliquely, then the circular muscles intersected by the bundles of perforating
muscles, and, finally, the bundles running in two rows through the supporting substance.

Both the intersecting bundles of muscles and the depressions on the surface of the
pedal disk (fig. 1) are wanting below the beginnings of young septa. This shows that
the muscular layers of the septa only grow secondarily into the supporting substance,
and that the depressions on the surface are occasioned by their becoming fastened to
its ectodermal side.

REPORT ON TIIE ACTINIARIA. 65

The function of the muscular bundles is easily seen ; they tend to raise the pedal
disk at certain points from the underlying substance, and by thus forming a vacuum,
cause the pedal disk to act like a sucker and secure the firm attachment of the animal.

The wall is 1 cm. thick, and is, moreover, remarkably firm, so that it furnishes a very
effectual protection ; it feels like cartilage or like the cellulose mantle of PhaUusia
maminiUutd, and, like the latter, easdy separates into shreds on division. Under the
microscope it shows a homogeneous fundamental substance in which fine filaments cross
in all directions, and form a thickly tangled layer. Each filament runs separately, and
can be followed some little way. From these the processes of the numerous minute cells
are to be distinguished by their greater thickness and fine granulation.

The surface of the wall rises in numerous knobs 0-5 cm. across, which often have a
small dark spot on the highest point ; they are commonly arranged, though irregularly,
in transverse and longitudinal rows. The wall feels otherwise quite smooth.

A special mesodermal circular muscle is present, even though in all the specimens the
oral disk was widely extended, and the wall only slightly or not at all contracted. The
circular muscle is of some breadth, as it measures nearly 2 cm., but its thickness can
hardly be measured without the microscope ; it lies close under the endoderm as a thin
layer of bundles of muscular fibres (PI. VI. fig. 3). If we consider that the body wall of
the animal is not only very thick, but of cartilagedike consistency, we can easily under-
stand that the contraction of the muscle is unable to effect rapid closure of the oral disk.

The bundles vary in strength, according as they consist of a smaller or greater number
of fine muscular fibres; in their lower third they form a single layer, in which there is no
perceptible further grouping ; farther up, the bundles become arranged in rows, and then,
as a larger quantity of connecting substance passes in between the rows, the latter
radiate to the number of nine or ten into the o-elatinous substance.

O

The wide oral disk, whose surface is covered with indistinct radial furrows, is not so
strong as the wall, but, in comparison with other Actinias, equally rich in cartilage-like
supporting substance. The radial muscles, whose bundles are compacted into a tolerably
thick and firm layer, be in the oral disk, separated from the ectoderm by a broad interme-
diate layer of supporting substance ; some of the bundles become detached from the
principal mass, and run through the fundamental connective tissue towards the endoderm,
where they terminate. As they cross each other on the way they form an irregular
network.

The tentacles are undeniably the most interesting portion of the oral disk, and
their odd form attracts attention even on a superficial glance. They consist of two parts,
a basal tuberous swelling, or bull), and a hollow process, or tentacle tube (PL II.
fig. 9 ; PI. IX. figs. 8 and 9). The bulb is formed by a strong thickening of the support-
ing substance; and since this is most extensive on the peripheral side of the tentacle,
the canal, which is not enlarged in other respects, runs eccentrically near the adaxial side.

(ZOOL. CHALL. EXP. — PART XV. — 18S2.) 1' 9

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

Another consequence of this peripheral thickening is the eccentric position of the
tentacle tube, which is thrust towards the adaxial side, where it rises in the form of a
short process bent slightly outwards. It is furnished at the end with a wide opening,
visible to the naked eye ; its surface is wrinkled in consequence of muscular contraction,
and its walls are brittle like those of other parts of the body.

The longitudinal bundles of the tentacles being prolongations of the radial muscles of
the oral disk are likewise mesodermal, though forced apart and into an irregular course
by the abundant connective substance (PI. IX. fig. 2) ; it is only near the point of the
tentacle that the muscular bundles are collected into a layer close under the endoderm
(PI. IX. fig. 6) ; they are consequently separated from their place of origin, the ectoderm,
by a wider interspace than in any other Actinia. The bundles, which are still strong in
the bulb, are, in the tentacle tubes, resolved by repeated division into very small groups
of fibrillas, if they have not ended previously as many of them do. In short, the tentacles
are, both from the extreme weakness of their muscles and from the stiffness of their
walls, very ill adapted for seizing upon prey, whilst, on the other hand, the wide
lumen of the terminal opening indicates their function as inhalent canals and tubes. We
have therefore plainly before us a process of transformation, which is further advanced
in Sicyanis and still more so in Polyopis and Polystomidivm, and wdiich consists in the
walls of the tentacle, its muscles, and its supporting lamella becoming reduced, whilst
the terminal opening becomes widened. The tentacles are first transformed into tubes,
and later into simple openings in the oral disk. As this is plainly the most important
characteristic of our Actinia, I have named the animal Polysip>honia on account of the
tubular nature of the tentacles.

The number of the tentacles amounts to nearly two hundred, perhaps to even more. They
are distributed in two alternating rows, which do not, however, describe a simple circle,
but are twelve times arched outwards at equal distances, so that the periphery of the oral
disk becomes twelve lobed. At each of the twelve points which project inwards and
separate the twelve lobes there is a remarkably large tentacle, which can easily be recog-
nised by the thickness of its bulb ; outside it, and belonging to the outer row, there are
two equally large tentacles, whose bulbs are fused together ; the other tentacles become
smaller the further they lie right and left from these fused tentacles, so that the
smallest are found on the outermost portions of the lobes.

The arrangement just described is still more plainly seen if we cut away the
tentacles and their basal swellings by a horizontal section ; this gives the figure shown
in Plate II. fig. 8, in which the position of the tentacles is shown by the transected
triangular canals. The mode in which the size of the tentacles gradually diminishes in
the two alternating rows is very characteristic of Potysiphonia tuberosa, and distinguishes
it from the majority of Actiniae. In the Introduction I laid down the following rules: — (1)
that the tentacles of one circle are commonly of the same size; (2) that the tentacles, if

REPORT ON THE ACTINIARIA. 67

t In ■y are not of the same size, become smaller in proportion as they belong to the more lately
formed intraseptal spaces. Neither of these rules applies to Potysiphonia iuberosa. A
glance at fig. 9 (PI. II.) shows at once the differences which take place in one and the same
circle, and if we go into the relations with the intraseptal spaces, we find that the twelve
largesl tentacles open into the twelve primary and secondary intraseptal spaces, whilst
the smallest of all the tentacles belong to the twelve tertiary intraseptal spaces. In
Polysiphonia the principle which regulates the size of the tentacles may be included in
the proposition, that the tentacles become smaller the further they are removed from the
twelve large tentacles of the first and second orders.

The oesophagus is tough and thick walled like the oral disk, whilst the septa are thin
like veils ; the oesophageal grooves and longitudinal furrows require no special description.
Of the forty-eight pairs of septa twenty-four are perfect, but the state of preservation of
all the internal organs of the species was such that I can say nothing as to the structure
and arrangement of the reproductive organs.

Polystomidium, n. gen.

Liponemidse, with longitudinal furrows and marginal spherules on the wall ; tentacles
transformed by retrograde formation into stomidia ; circular muscle endodermal.

In the Poly stomidia, the tentacles have undergone retrograde formation to an extent
which has hitherto been observed only in the genus Polyopis; the only traces of them
are the terminal openings, which lead directly into the radial chambers and are surrounded
by swollen margins, the remains of the tentacle wall. In their habit of body, in the
endodermal position of the circular muscle, and in the presence of the marginal spherules,
these animals are allied to the Antheadae.

Polystomidium patens, n. sp. (PL V.).

Body dish-shaped, widening from the small pedal disk to the wide oral disk ; stomidia
in two alternating rows.

Habitat— Station 296. November 9, 1S75. Lat. 38° 6' S., long. 88° 2'W. Depth,
1825 fathoms. One specimen.

Dimensions. — Diameter of the oral disk, 6 cm.; diameter of the pedal disk, l-5 cm. ;
height of the wall, 2" 7 cm.

Colour. — (Determined from the spirit specimen) brownish-grey, the endodermal parts
brown-violet, except the filaments which were coloured white.

Of this interesting deep-sea Actinia, which I have placed here under the name Poly-
stomidium patens as the representative of a new genus and new species, I had unfor-
tunately only one specimen at my disposal, and it had been so severely injured in being
dredged from the depth of 1825 fathoms, that it was in a condition but little adapted
for minute examination. The body was flattened into a cake, of which one side was com-

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

pletely covered with parts of the thin-membraned lamellae of the septa, hanging in tatters,
and with the reproductive organs and mesenteric filaments. The latter protruded partly
from the oesophagus, partly from rents and fissures in the oral disk and wall, and partly
from the openings, which replace the tentacles and represent them morphologically.

After the tattered fragments had been partially removed, it was found that one side
of the Actinia was formed by the oesophagus and oral disk, the other by the wall and the
pedal disk (fig. 3). The pedal disk is only slightly distinguished from the wall as a shallow
depression 1*5 cm. in diameter, the bottom of which forms a convex projection into the
interior of the gastric space of the Actinia. The wall, which is about 27 cm. long, shows
distinct longitudinal furrows, which run from the margin of the pedal disk to the margin
of the oral disk, and indicate externally the origins of the septa. As they amount to more
than seventy in number, they correspond to thirty-six pairs of septa, which were also
visible on dissection. Small knobs, which may perhaps be compared to the " bourses
marginales" of other Actiniae, lie one in each of the interspaces between these longitudinal
lines, at a little distance from the margin of the oral disk. The surface of the wall is
otherwise qnite smooth.

The endodermal circular layer of fibres is pleated as far as the wall extends, and rises
in muscular folds, which usually remain simple or are only slightly branched (fig. 10).
The folds are more extensively branched only in the uppermost section of the body,
where they form a sphincter which lies between the marginal spherules and the corona of
stomidia, somewhat below the latter, and causes the wall to project outwardly (fig. 8).
A longitudinal section through the wall, therefore, shows us two evaginations lying at the
upper end, the one above the other, in which the supporting lamella becomes very much
thinner. The lower one is caused by the marginal spherule, the upper by the circular
muscle ; the former contains a hollow space and is lined by a weak muscular layer,
the interior of the latter is almost completely filled by the deep muscular folds,
whose arrangement is more minutely given in fig. 9. The ramification of the separate
folds decreases both above and below, so that the circular muscle is gradually transformed
into the usual muscular layer.

The entire absence of the tentacles is a striking feature of the oral disk ; they are
replaced by openings like buttonholes (fig. 6), which I shall term " stomidia," and on
account of which I have named the genus PoJystomidiicm. Their exact number coidd not
be directly determined, as the oral disk was greatly injured in many places, but, bearing
in mind their relation to the septa, it may be estimated at about seventy-two. In
dissecting the septa we find that one stomidium opens into each radial chamber. The
stomidia belonging to the intraseptal spaces are usually smaller, and form an inner circle
by themselves ; the stomidia of the interseptal spaces alternate with them, and are placed
in an outer circle ; their longitudinal diameter runs in a radial direction, and amounts to
about 0'5 cm.

REPORT ON THE ACTINIARIA. 69

The constitution of the margins is the standard by which I have determined that the

stomidia may he normal j >ln nomeiia and not merely rents in the oral disk. The outer
stomidia leading into the interseptaJ spaces are separated from one another by narrow
ridges, which have arisen from the septa, belonging to a pair converging upwards and
becoming directly united. The roof of an intraseptal space furnished by the oral disk,
which is usually of considerable breadth, has consequently undergone almost complete
retrograde formation. Towards the oral opening the stomidia are surrounded by swollen
lips, folded like frills ; these arc still more perceptible on the inner stomidia, round
which they form a border.

As the arrangement of the stomidia follows that of the tentacles in other Actiniae,
there seems no doubt that they represent the latter morphologically. I have already
shown iu the Introduction that they may be derived in the most simple way from the
tentacles if we assume that the wall of the tentacle has become contracted into the
encircling lip-swelling, whilst the terminal opening has become proportionably widened.

The oral disk is thickly pleated inwards from the stomidia, and covered with radial
swellings, which lie between the insertions of the septa and gradually disappear towards
the oral opening. The radial muscular fibres do not pass into the mesoderm, but remain
in the ectoderm ; like all muscular fibres of Polystomidium, they are very powerful, and are
united into a thickly-pleated lamella. The muscular folds are specially high in the
peripheral parts of the oral disk, where they lie thickly compacted and repeated! y
branched (figs. 4 and 7).

On the oesophagus there is a remarkable circular fold, which runs at a little distance
below the labial margin, and marks off in this way a small upper section of the oesophagus.
Openings, equal in number to the stomidia on the oral disk, lie in this section, and lead
directly into the radial chambers (fig. 1). I have only observed similar formations in
Polyopis striata, another Actinia in which the tentacles have undergone retrograde
formation. The lower section of the oesophagus is covered with numerous longitudinal
furrows. Besides these there are two well-marked oesophageal grooves, and two long
oesophageal lappets, by which the directive septa can be easily determined.

The number of the septa is smaller than in most of the larger Actiniae. Calculating
the number in the entire animal from the quadrant in which I dissected the septa, and
from the longitudinal lines on the surface of the body, there are altogether thirty-six pairs
of septa ; six pairs of principal septa of the first order, six pairs of the second order, and
twenty-four pah's of the third. The last number is very remarkable, as there are usually
only twelve pairs of septa of the third order. In consequence of this the interseptal
spaces of the second order are divided, not as usual into two, but into three interspaces,
because of the duplication of the septa of the third order. In this way Polystomidium
patens shows a variation from the regular conditions of the hexamerous A-Ctinise.

The muscular part of the septa is very thick and powerful, and uniformly strong

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

throughout ; their longitudinal muscular fibres are developed iuto a repeatedly
folded muscular lamella, whilst their transverse fibres are weak. The parietobasilar
muscle, which springs from the small pedal disk, and reaches half-way up the wall, is also
weak (fig. 2).

The greater part of the thin-membraned portions of the septa had been torn away ;
where they still remained they lay in the interseptal and intraseptal chambers, from
which they protruded through the stomidia. They contained the reproductive organs, the
specimen examined by me being a male. The follicles, filled with spermatoblasts and
spermatozoa, are not so thickly compacted as in most other Actiniae, but rather isolated and
of considerable size, so that they can be separately recognised with the naked eye placed
beside one another hike paving-stones.

All the septa reach the oesophagus ; the upper part only of the forty-eight septa of
the third order is connected with the oesophagus, whilst the others extend much farther
downwards ; they are all pierced by peristomial openings, forming a circular canal in the
aggregate. The only difference between the septa — apart from size — seems to be that the
principal septa are without reproductive organs. I must, however, remark that in conse-
quence of the numerous injuries, it is impossible to make any positive statements as to
the distribution of the reproductive elements upon the septa.

All the surfaces of the wall and of the septa covered with endoderm are brownish-
violet, as numerous pigment granules are deposited in the epithelium. The mesenteric
filaments, which I have figured in transverse section in fig. 5, form the only exception ;
they are whitish like the ectodermal parts, and are distinguished in this way from the
dark ground of the septa on which they run in numerous meandrous curves.

Family, Sagartid^e, Gosse.

Sagartince= Phellince, Verrill.

Hexactinise with acontia, a strong mesodermal circular muscle and numerous very
contractile tentacles ; the principal septa, or septa of the first order, only are perfect and at
the same time sterile ; all the remaining septa are imperfect.

In my researches on the Actinias, which have already extended over a very large
amount of material, I have almost always found two characters combined, (l) The pre-
sence of filaments known as acontia near the lower end of the mesenteric filaments ; they
float freely in the gastric cavity, are thickly covered with nematocysts, and if danger
threatens can be protruded quickly as weapons of defence. (2) The six pairs of principal
septa only reach the oesophagus, all the others being imperfect. Reproductive organs
are found only on the secondary septa, of which, however, the older are often per-
manently sterile.

!\iy brother and I first observed these facts in Adamxia dia/phana, Metridium dianthus,

UKl'OUT ON THE M TIMAIM \. 71

and Calliactis [Sagartia) parasitica ; I have been able to corroborate them in five different

speeies of the Challenger material, and found, moreover, that in no instance, where the
acontia wore present, was the differentiation <»f the septa wanting, and that tin
Amphianthidse were the only Actiniae in which the acontia were absent, though the
septa showed the Sagartid type. I therefore feel justified in making use of both
characters to limit a family of Actinia?, which I still term Sagartidse, as most of
the forms belonging to it have been determined as such by former authors.

A third characteristic is common to all Sagartidse, viz., the presence of a strong
mesodermal circular muscle, but this is only of subordinate value, as it occurs in other
families.

Nearly all the descriptions published of the Sagartke and the closely allied forms are
unfortunately so imperfect that it is impossible to determine how far the forms hitherto
described come under the above diagnosis. As yet, we can only assume this to be
definitely the case in Sagartia schUleriana, discovered by Stoliczka (Journ. Asiat. Soc.
Bengal, vol. xxxviii. part ii. p. 28-63, 18G9). Another form, Sagartia troglodytes, may,
on the other hand, be considered as an exception; v. Ileider states (Sitzungsber. der
Wiener Akad., Math. Naturw. CI., Bd. lxxv. Abth. 1, p. 367, 1877) that in it forty-eight
pairs of septa reach the oesophagus, and at the same time describes formations in it,
which undeniably are acontia, though the author does not distinguish them from the
mesenteric filaments. However, as I have already specially remarked, I am doubtful
whether v. Heider has not confused sections through the oral disk with sections
through the oesophagus, and consequently over-estimated the number of the perfed
septa. Such a mistake might easily occur in highly contracted animals like those
which he examined.

As far as we can judge at present, the family of the Sagartidse, as I have now
defined it, would coincide on the whole with Gosse's Sagartidse. The most essential
difference is that I have included the genus Bunodes in it. In so doing I relied upon the
examination of a single species, which showed externally the arrangement of papillae
characteristic of the Bunodes, but which must be placed among the Sagartidse, from its
anatomical constitution. It remains for future observers to determine whether the
structure is the same in the other species as in our Bunodes minuta ; at present
it is quite possible that perfectly heterogeneous species have been included under the
same generic name. It must, however, be borne in mind that Verrill (Transact. Connect.
Acad., vol. i. p. 467) and Jourdan do not attribute any acontia to the genus Bunodes,
and Gosse (Actinologia Britannica, p. 204) only to a single species.

Verrill has separated the sub-family of the Phellinse from the Sagartidse, an innovation
of which I do not approve, as there are transition forms between Sagartia and Phellia.
The cuticular secretion, the "epidermis" of the said authors, which covers the wall
of Phellia as far as a ring close under the tentacles, is present, though less highly

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

developed, in Cereus spinosus, but is not so sharply confined to definite parts as in
Phellia.

After what has been said in the preface, no further explanation is required as to my
reasons for omitting the cinclides in the general character of the family. I shall hence-
forward mention the cinclides only in cases where they can be observed anatomically
by transverse and horizontal sections, or by observation with the naked eye. This is
possible in a number of species belonging to the genus Calliactis. In Cattiactis
parasitica there are openings at certain points, having swollen margins, which project
somewhat above the surface of the wall ; they can be easily observed even in the dead
animal, but they are so distinct in the living Calliactis that they have been already
described and figured by earlier naturalists, such as Forskal (Descriptiones animalium,
&c, 1775), Ehrenberg, and Dana. This is not the case in the majority of the Sagartidse.

Sagartia, Gosse, pro parte.
Sagartia, Verrill.

Sagartidse with smooth wall and numerous powerful tentacles arranged in several
rows ; with circular oral disk ; without anatomically perceptible cinclides.

Though I agree as far as possible with Verrill in the limitation of the genera, I restrict
the genus Sagartia to forms in which it can be shown at most that the acontia pass out
through the wall, but in which, however, no openings can be pointed out, either because
they are not preformed or because they are so small and indistinct as to be easily over-
looked even with most careful observation. The genus Sagartia is distinguished in this
point from Calliactis ; it is, moreover, distinguished from Cereus, Bunodes, and Phellia by
the smooth nature of the wall, arising from the absence of papillae and cuticular excretions,
and finally from Metridium by the circular shape of the oral disk, and by the powerful
development of the tentacles.

Sagartia, sp. ?

Body flattened like a cake in the contracted condition ; tentacles nearly two hundred
in number, placed in five rows, and decreasing in size from within outwards ; muscles
of the tentacles and of the oral disk ectodermal, hardly at all pleated.

Habitat.— Station 194. September 29, 1874. Lat. 4° 33' S., long. 129° 58' E.
Depth, 360 fathoms. One specimen.

Dimensions. — Diameter of the pedal disk, 4 cm.

Colour. — (Determined from the spirit specimen) whitish on the whole, the middle
third of the wall yellowish- red.

There was only a single specimen of a true Sagartia in the Challenger material. It
was attached to a very porous stone of volcanic origin, but it was so strongly contracted,

REPORT ON THE ACTINIARIA. 73

and its external appearance presented so little that was characteristic, that I gave up the
idea of determining the species more closely, and only decided to give a description of it
in order that the important genus might not be left unrepresented.

The animal was so strongly contracted that its body formed a cone, nearly flattened
into a disk, the base of which measured 4 cm., whilst its height measured little more than
0'5 cm. The surface of the animal is extremely smooth ; it is whitish at the base,
then assumes a yellowish-reddish colour, which again passes gradually into white. The
coloured part appears longitudinally striated, because the red and yellow alternately
predominate in the ground-tint.

The wall is on the whole thin-membraned, and becomes about six times as thick
only at the upper margin. This very unusual increase in bulk is explained partly by
the high degree of contraction, partly by the great strength of the mesodermal circular
muscle. The latter occupies nearly the entire thickness of the wall, and is only separated
from the ectoderm by a very thin layer of connective substance, whilst a rather broader
layer separates it from the endoderm. Its contour corresponds to the form of the wall, so
that it is broad above and drawn out to a point below. We rarely find such beautiful
primitive bundles in transverse section as in our Sagartia ; they are formed of strong
fibril lae, are regularly oval or rounded circularly, and of medium size. On the other
hand, the way in which they run is remarkably irregular. In the same transverse
section we find, side by side, bundles, some divided obliquely, and others divided perpen-
dicularly, and we see in the thicker parts of the section how the bundles cross and become
interwoven in their course.

Contrasted with the circular muscle, the radial muscular fibres of the oral disk and of
the tentacles are only sbghtly developed, and form a very slightly pleated layer in the
ectoderm. The tentacles are limited to the periphery of the oral disk, where they are
arranged in five rows, and decrease a little in size from within outwards. They are
of medium length, rather slender, and pointed at the end. I counted twenty-five in about
an eighth of the animal, so that there are probably one hundred and ninety-six in all.

From transverse sections taken through the oesophagus I estimated the number of
septa at forty-eight pairs, of which the six principal pairs only are perfect. There
would probably be a much larger number at the base, as small septa reaching only a
little way project there, in the angle between the pedal disk and the wall. There were
reproductive organs (mature testes) on all the larger secondary septa. Finally, in
transverse section, I could perceive wide openings in the septa near the wall.

Calliactis, Verrill.

Sagartidse with smooth wall and numerous tentacles, with distinct cinclides which
pierce the wall not far from the base in one or several transverse rows.

(ZOOL. CHALL. EXP. PART XV. — 1882.) P 10

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

Following Verrill's example (Trans. Connect. Acad., vol. i. p. 481), I have sepa-
rated the genus Calliactis from Sagartia, as in it we find distinct cinclides constantly
present in a circle above the base. They are easily made out in a fresh state, and often
after treatment with reagents as warts, into which a small evagination protrudes from
the gastric space, so that the membrane of the wall becomes much thinned away ; an
opening, which it is more difficult to find, lies in the middle of the knob. If the knobs
do not project sufficiently above the surface, it is merely necessary to remove the uppermost
layer of the wall by means of a section parallel to the surface in order to make the cinclides
which traverse the thickness of the supporting substance distinctly visible ; this method
answers very well, if we wish to determine the number of cinclides in preserved specimens
of Calliactis.

The forms belonging to this genus agree so far in their manner of life that they are
only found upon Gasteropod shells, the interior of which is occupied by a Pagurus. Their
best known representative is Calliactis (Sagartia) parasitica, in which my brother and I
have made out and described the cinclides ; other forms are Calliactis polypus, Calliactis
decorata, and Calliactis variegata. All these species are difficult to distinguish in a
preserved state, as the colour has usually formed an important point in their definition.
The forms of Calliactis in the Challenger material appear to me identical with Calliactis
polypus ; none of them belong to Calliactis parasitica.

Calliactis polypus.

Priapus polypus, Forskiil, Descriptiones animalium, p. 102, tab. xxvii. fig. C, 1775.
Cribrina 'polypus, Ehrenberg, Corallen. d. roth. Meeres, p. 40, 1834.
Adamsia priapus, Milne-Edwards, Hist, des Corall., torn. i. p. 280, 1857.
Calliactis polypus, Klunzinger, Korall. d. roth. Meeres, i. p. 76, taf'. v. fig. 1, 1877.

Wall smooth, with a circle of 24 cinclides ; tentacles long and slender, above 600 in
number, placed in numerous circles, decreasing in size from within outwards ; twelve ten-
tacles in the innermost circle, twelve in the next, twenty-four in the third, and so on.

Habitat.— (a) Station 208. January 17, 1875. Lat, 11° 37' N., long. 123° 32' E.
Depth, 18 fathoms. Three specimens on one Gasteropod shell, (b) St. Vincent, Cape
Verde Islands. Six specimens on one Gasteropod shell.

Dimensions. — Breadth of pedal disk up to 4 cm. ; height up to 3 cm.

The specimens of Calliactis polypus, taken at two different places, lay, in the one
case, in a group of six individuals on the shell of a Natica, and in the other in a group
of three on the shell of a Murex. They were, however, all contracted into a shallow
conical mass, at the point of which the tentacles appeared here and there, as Klunzinger
has abeacly described in this Actinia.

The pedal disk is very large, and firmly fastened to the shell by means of a brownish
mass. The wall is smooth, and only folded longitudinally above in consequence of
contraction ; it is tough and opaque except in a small portion adjoining the pedal disk,

REPORT ON THE ACTINIARIA. 75

which is thin as paper, and through which the insertions of more than one hundred
and fifty septa are visible. The cinclides form a single circle at a little distance from the
pedal disk ; they are placed irregularly, sometimes higher, sometimes lower and closer to the
disk. Their walls rise above the surface in places like an hour-glass ; where this is not the
case they cannot be seen from the surface, and only become visible after the superficial
layer of the wall has been removed by a section parallel to the surface in the manner
already specified. Their number seemed to amount invariably to twenty-four ; they open
into the intraseptal spaces of the first three orders of septa.

The circular muscle at the upper end traverses the entire mass of the wall, which is
trebly thickened at this point, but is separated from the eudodcrm by a narrow layer of
connective substance, from the ectoderm by a rather broader layer of connective
substance ; it is most powerful in the middle, and becomes weaker above and below ;
above, it reaches as far as the origin of the oral disk, where at the same time it most
closely approaches the two layers of epithelium.

The bundles of muscular fibrilke show a tendency to arrangement in parallel layers,
placed one above the other as in Phellia pectinata (PI. VI. fig. 5) and Cereus spinosus
(PI. VI. fig. 1), though not so distinctly as in the latter species. Each layer again
consists of a number of smaller and larger groups of bundles of fibrillse, placed in a line
one behind the other, and each bundle, in transverse section, is divided by constrictions
of its surface into lobes which are sometimes more, sometimes less distinctly separated
from one another. The muscular fibres which occupy the periphery and enclose the pro-
toplasmic axis in an undulating layer, are of medium strength.

The arrangement of the bundles of fibrillse in layers becomes less distinct above and
below ; above, because the bundles are so pressed together that only a scanty framework
of the separating connective tissue trabecule remains ; and below, because, on the other
hand, the bundles become very small and are isolated from one another. Finally, the
bundles of fibrillse become flatter from the outside towards the inside, but this is merely
in consequence of the contraction of the animal.

The circular muscle of Calliactis polypus described above, is chiefly distinguished
from the circular muscle of Calliactis parasitica, which we have already investigated
(Actinien, p. 180), by not being divided into two distinct parts. There are also differences
in the muscular system, which enable us to distinguish the two species in a preserved
condition. I refer to the radial muscles of the oral disk, and to the similarly constructed
longitudinal muscles of the tentacles.

The radial muscular fibres in Calliactis polypus form a thick layer which is always
thinned away above the insertions of the larger septa, and so divided into broader and
narrower radial bands. Their figure in transverse section is difficult to make out ;
at first sight it gives the impression that masses of compacted muscular fibres,
placed in repeated layers the one above the other, have been deposited between the

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

supporting lamella and the layer of nerve fibres of the ectoderm. Jt is necessary to
employ a staining fluid (picro-carmine), which impregnates the supporting substance
strongly, in order to distinguish a framework of connective tissue between the muscular
fibres ; and as this gives rise to extremely fine-walled meshes, it divides the muscular
fibres into mesodermal bundles of fibrillar. Numerous supporting layers run out from the
surfaces of the supporting lamellae, and these ramify and anastomose with one another.
The anastomoses are wanting towards the ectoderm, so that the meshes open towards the
layer of nerve fibres ; the muscles are consequently partly mesodermal, partly ectodermal.

In Calliactis p>arasitica the boundary line between the mesodermal muscles and the
ectoderm is also indistinct, but the bulk of the former is much smaller, so that sparse
bundles only are enclosed in an abundant fundamental substance.

The tentacles of Calliactis pxylypus are long, slender, and end in a fine point. I made
out about seventy in a twelfth part of the animal, so that altogether they amount in
number to several hundreds, which decrease in size from within outwards, and are
arranged in about ten circles. The first and second circles, beginning at the inside, each
contain twelve tentacles placed somewhat apart, the third twenty-four tentacles, the
fourth forty-eight, and so on.

If we take the well-developed septa only into consideration, there are altogether

our cycles or forty-eight pairs, the first six pairs of which are perfect. The following

six pairs are imperfect and sterile like the first six, so that the reproductive organs are

confined to the septa of the third and fourth orders. The specimen examined by me was

a male, and contained ripe testes.

Cereus, Oken.

Sagartidse, with numerous tentacles and circular oral disk, without cinclides which
can be anatomically demonstrated ; wall rough, and covered with knobs.

Milne-Edwards (Hist, des Corall., torn. i. p. 263) included all the more typical represen-
tatives of his " Actinines verruqueuses " in Oken's genus Cereus. After it had been
shown that acontia existed in Cereus bellis, which had been taken by Oken as the typical
representative of the genus (Lehrbuch d. Naturgeschichte, Th. III. Abth. 1, p. 349, 1815),
Verrill limited the name to forms of the family Sagartidse. I agree with Verrill on this
point, but wish to attach more importance in the diagnosis to the papdlose nature of the
wall, in order to establish a sharp distinction between this genus and Sagartia. I have
therefore altered the description of the wall, which runs thus in Verrill : " upper part
with small, inconspicuous contractile suckers ; walls nearly smooth."

Cereus spinosus, n. sp. (PI. I. figs. 3-5; PI. VI. fig. 1 ; PL VIII. fig. 6; PL XII. fig. 10).

Papillae of the wall unequal in size, with a tendency to arrangement in transverse and

longitudinal rows ; each papilla runs out into a fine point, which is placed on a hemi-

REPORT ON THE ACTINTAETA. 77

spheroidal base ; surface of the wall rough and bark-like ; tentacles tolerably long, placed
in three rows decreasing in size from within outwards.

Habitat— {a) Station 157. March 3, 1874. Lat. 53° 55' S., long. 108° 35' E.
Depth, 1950 fathoms. One specimen, (b) Station 237. June 17, 1875. Lat. 34° 37'
N., long. 140° 32' E. Depth, 1875 fathoms. Four specimens.

Dimensions. — Diameter of the pedal disk, 5 cm. ; height, 7 cm.

Colour. — (Determined from the spirit specimen) a dirty violet.

The new species, which I have named Cereus spinosus, was found at two different
places. The first time there were several specimens, which were unfortunately preserved
in chromic acid, and thus rendered of no practical use. The second time there was only a
single specimen, which was very well preserved in spirit, and from which the following
description is exclusively taken.

The colour of the body was a dirty violet in all parts to which the spirit had easy
access, whilst in other parts it had become discoloured into a greyish-yellow. For ex-
.ii ii] ile, the outer tentacles were violet, and so were the points of the inner tentacles, whilst
the bases of the latter were yellowish. This was caused from the animal being in a semi-
contracted condition, in which portions of the tentacles project freely.

It was plain that the pedal disk had been attached to a very narrow underlying
substance, and had consequently acquired a very irregular shape. Part of the disk
surrounded the stalk of a Hyalonema, which was consequently enclosed in a canal, so
that the edges of the disk are not only placed firmly one against the other, but have
actually become fused. The pedal disk is otherwise opaque, tough, and knobbed, and
thus presents a bark dike appearance.

The surface of the wall is likewise very rough. Its lower third is covered with
circular furrows, which are placed at a little distance from one another, and run parallel
to the margin of the pedal disk. At the upper end the furrows lie further apart and
become irregular, whilst at the same time they are crossed here and there by longitudinal
furrows. The numerous knobs with their pointed ends, on account of which I have named
the species Cereus spinosus, deserve special attention ; they show a tendency to arrange-
ment in transverse and longitudinal lines, but are wanting in some places, whilst they are
thickly compacted in others. In the upper third of the wall they are of considerable size,
begin with a broad hemispheroidal base and end in a thorn-like point, marked off by its
dark brown colour from its surroundings. Lower down the knobs become smaller, and are
finally merely minute pointed knobs, which are very firm, and coloured an intense brown.

The bark-bke appearance of the pedal disk and wall is owing to a cuticular deposit
(the " epidermis " of former authors), in which we can distinguish two layers (PI. VIII.
fig. 6). The surface of the epithelium is covered first of all by a yellowish, irregularly'
fibrous border, which is torn in some places, and raised here and there in tube-shaped
processes, of which one is shown in fig. 6, 6. Outside the fibrous border comes a granular

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

mass traversed by foreign bodies. The epithelium lying below this deposit is without
cilia, and varies very much in height; the epithelial stratum sometimes shrinks to an
almost invisible layer, and sometimes rises into long, filamentous cylindrical cells.

The Avail in Cereus spinosus is very thick (as much as 3 mm. in transverse section),
tough, and leathery as in the majority of Sagartida3. It is constricted at the upper end
by a circular muscle, wdiich, in spite of its strength, is entirely concealed in the mesoderm
of the wall. The muscle is nearly 1'5 cm. long and nearly 2 mm. broad in section at
its upper end, whilst it becomes narrow below as usual. It is separated both from the
ectoderm and the endoderm by a layer of connective tissue, 0"5 mm. broad, and without
muscles. Seen in transverse section (PI. VI. fig. 1), the muscular fibrdlas in the upper
half of the muscle form rows rising from within and below, obliquely upwards and out-
wards ; they are separated by broad bands of connective tissue, and placed in tiers one
above the other. Here and there a row consists of a single flattened primitive bundle, the
indentations of whose surface indicate its tendency to split up into a series of smaller
bundles. This process has, however, usually taken place, so that each single tier is
composed of a series of smaller roundish bundles and larger flattened bundles. Two
successive tiers of bundles are not completely separated, but connected by a network of
thin branched anastomosing cords ; the bundles of each tier are connected with one
another in the same way. The former is visible in sections taken parallel to the surface
of the wall, the latter in sections parallel to the base of the animal.

The character of the muscle changes in the lower half as the bundles of fibrillse are
scattered at considerable distances from one another. The larger bundles are lobed in
transverse section, or resolved into a group of smaller bundles of fibrillae.

The radial striation is distinctly marked on the oral disk, and is caused by the manner
in which the muscles are arranged, while this again is correlated with the distribution of
the tentacles. The radial muscular layer is ectodermal and pleated very uniformly, so that
the single folds of muscles are only slightly branched, and lie beside one another like
the leaves of a book. Besides this uniform pleating, the enlargement of the muscular
layer is due to the fact that the supporting layer is thinner at the insertions of the septa,
but becomes thickened above the middle of each interseptal space, where it forms a sharp,
roof-like ridge. The ridges formed in this way produce the radial striation of the oral
disk already mentioned ; seen from the surface, they do not project very sharply so long
as they are covered by epithelium, which in a measure reduces their inecpialities. The
ridges begin near the margin of the mouth (PI. I. figs. 4 and 5) ; they are forty-eight
in number, twenty-four corresponding to the intraseptal spaces of the first, second, and
third orders, and the other twenty-four to the intermediate interseptal spaces. The first
twenty-four are broadest near the margin of the mouth, become narrower towards the
periphery, and end on the twenty-four tentacles of the innermost row, where they run a
little way divided into two by a shallow furrow. The second twenty-four ridges differ,

REPORT ON THE ACTINIARIA. /»

inasmuch as they are broadest towards the periphery, where they are each divided by two
long radial furrows into three ridges, a middle ridge belonging to one of the twenty-four
tentacles of the second cycle, and two lateral ridges which pass on to two of the
forty-eight tentacles of the third cycle. This division corresponds at the same time to
the arrangement of the septa, the twenty-four interseptal spaces are divided in the
periphery by the twenty-four pairs of septa of the fourth order into three compartments,
an intraspace and two interspaces.

The number and mode of arrangement of the tentacles may be deduced from what
has been said. We find altogether ninety-six tentacles distributed in three rows, twenty-
four in the first or innermost row, twenty-four alternating with them in the second row,
and forty-eight in the third row. This is best seen if we cut away the tentacles, leav-
ing only the short basal stumps (PI. I. fig. 4). The tentacles have a slender shape,
diminishing uniformly from the base towards the point ; they are distinctly striated longi-
tudinally and perforated at the end by a fine opening ; they are largest in the innermost
row, where they attain a length of 2 cm. The longitudinal striation is caused by elevations
of the supporting lamella, which are covered moreover with small folds bearing the muscles.
The boundary between the oral disk and the oesophagus is only indicated by a slightly
swollen Up. The oesophagus has tolerably broad oesophageal grooves and short oesophageal
lappets ; it also shows eleven powerful longitudinal swellings on either side (fig. 5).

The arrangement of the septa is governed by the same principle, which has been
akeady laid down as applicable to most Sagartice. Its characteristic is, that only the
six pairs of principal septa, of which again two pairs are directive septa, reach the
oesophagus. The principal septa are, at the same time, exclusively muscular septa, i.e.,
they do not develop reproductive organs. Their muscular systems are not very strong ;
for example, the parietobasilar muscle is merely a slight fold ; the most distinct among
them are the longitudinal fibres, which rise obliquely from the wall and the base to the
oral disk. An internal septal stoma is certainly present, but so small as to be easily
overlooked ; an external septal stoma is wanting.

The principal septa are followed by three cycles of imperfect septa ; the development of
their muscular system is far behind that of the principal septa, but, on the other hand,
they are furnished with reproductive organs (in the present case with ovaries). In each
cycle they become smaller, and project less into the gastric space and towards the pedal
disk and oral disk. The last forty-eight pairs are hardly recognisable as longitudinal lines
on the wall, and merely project as folds in the angles formed by the wall on one side and
the oral disk or pedal disk on the other (figs. 4 and 5, h*). The reproductive organs lie
highest up, and quite hidden by the oesophagus on the septa of the second order (figs.
4 and 5, h2) ; in the septa of the third order they are visible under the lower margin of
the oesophagus (figs. 4 and 5, h8), while in the septa of the fourth order they are insignifi-
cant bodies, confined to the lowest section.

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

The free margin of each septum is occupied by the mesenteric filament. The upper
section is tripartite, the lateral ciliated streaks still lying beside the median glandular
streak, whilst the lower section is simple, and formed merely of the glandular streak.
This last comports itself differently on the different septa ; in the septa of the first and
second orders it is disposed in meandrous curves and coiled into a thick mass, which,
in the septa of the first order, is visible beneath the margin of the oesophagus, whilst it is
covered by the latter in the septa of the second order ; in the other septa it appears
as a slightly waved border. The acontia common to all Sagartice, and of which one at
least is found in each septum — even in the small septa of the fourth order- — -arise at a
little distance from the lower end of the mesenteric filaments. In transverse section the
acontium shows a roundish figure flattened somewhat to an oblong (PL XII. fig. 10).
On one of the longer sides there is an indentation, the expression of a groove which runs
on the acontium as far as its point of attachment to the septum. Histologically we can
distinguish an axis of connective tissue and a cylindrical epithelium, containing numerous
nematocysts, especially on the side of the acontium remote from the groove. In
Calliactis p>ctrasitica, we had previously distinguished fine muscular fibres and a layer of
nerve fibres ; these doubtless exist in Cereus spinosus, but the specimen was not well
enough preserved to admit of their being made out plainly.

If we open a Cereus spinosus by a longitudinal incision we can distinguish the different
pairs of septa, without further dissection, by the constitution of the reproductive organs
and of the mesenteric filaments (fig. 5). The pairs of septa of the first order (h1) are
recognisable by the thick coils of mesenteric filaments, which spring from them below
the oesophagus, whilst the pairs of septa of the second order (Ii2), the reproductive
organs and mesenteric filaments of which are usually completely covered by the oesopha-
gus, appear only as sharply defined lamellae with smooth margins ; in the septa of the
third order (hs), in which the coils of filaments are wanting, the ends of the reproductive
organs project from beneath the lower margin of the oesophagus, whilst the pairs of septa
of the fourth order are so small as to be quite out of sight.

Phellia, Gosse.

Sagartidse with a rough, cuticular sheath, which is firmly attached to the epithelium,
and leaves the upper part of the wall free ; the latter is smooth and becomes inverted
during contraction ; cinclides not demonstrable anatomically ; tentacles small, and few
in number.

The cuticular sheath, which we have already found in Cereus spinosus, is still
more strongly developed in a number of Actinia?, but is here confined at the same
time to one part of the wall, leaving the other part free. Close underneath the
corona of tentacles, the free part of the wall forms a broader or narrower ring,

REPORT ON THE ACTINIARIA. 81

which is soft-membraned and smooth walled, is pretty sharply defined from
the bark-like section of the wall, and, like the oral disk, is inverted during con-
traction. Gosse formed the genus Phellia for these Actiniae, which are easily recognised
even by a superficial observer (Ann. and Mag. of Nat. Hist., ser. iii. vol. ii. p. 192) ;
Verrill went a step further, and erected them into a special sub-family, though in so doing
he attached undue value to the character.

Jourdan was the first to explain the essential nature of this formation by pointing out
that the bark-like layer is merely a deposit on the ectodermal epithelium, and that the
latter has undergone retrograde formation under this deposit so as to become an imper-
ceptible layer (Annales des Sciences Nat. Zool., ser. vi. t. x. p. 98).

Verrill has made some statements about the internal structure of the Phellia; (Transact.
Connect. Acad., vol. i. p. 490), which refer to Phellia panamensis; the ovaries arc
irregularly distributed on the septa, are wanting on the smaller, and present only on the
twelve largest. This so flatly contradicts all observations on the distribution of the repro-
ductive elements in the Actinias, that Verrill must somehow have been mistaken. His
observations are of no use for another reason, namely, that he says nothing about the
relation of the septa to the oesophagus.

Phellia pectinata, n. sp. (PI. I. fig. 7 ; PI. VI. fig. 5 ; PI. VIII. figs. 1, 2, and 10).

The bark-like part of the wall is covered with transverse and longitudinal furrows ;
terminating above in twelve knobs, which are prolonged on to the inverted soft-
membraned section as twelve longitudinal combs ; each comb ends in a very prominent,
bifurcated, nose-like projection ; tentacles small, pointed, arranged in four cycles.

Habitat.— Station 307. January 4, 1876. Lat. 49° 24' S., long. 74° 23' W. Depth,
147 fathoms. One specimen.

Dimensions. — Height of the wall (taken as far as the inverted soft-membraned part),
2 cm. ; breadth, 1*5 cm.

This animal, which I have incorporated as a new species in the genus Phellia, would
hardly be taken for an Actinia by any one who glanced at it in a contracted condition ; its
small body, about 2 cm. high and l-5 cm. broad, rather resembles the body of a Cynthia,
perhaps Cynthia canopus ; it has the same rough, somewhat shaggy surface, the same
leather-like consistency, the same oval form having an opening at the one end, whilst a
second opening similar to the egestive opening is naturally wanting. This constitution
of body is explained by the peculiar fashion in which the animal contracts itself; during
this process not only the oral disk and corona of tentacles, but the upper part of the wall
is so deeply invaginated that not the smallest part of the tentacles nor of the oral disk
remains externally visible.

As in every Phellia we can distinguish two sections in the wall, a lower sec-
tion which does not, and an upper part which does, become invaginated. The two

(zool. CHALL. ESP.— FART XV. — 1882.) P 11

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

parts are very differently constituted. The former, which is the only part externally visible,
is covered with transverse wrinkles, crossed here and there with longitudinal furrows.
It terminates above in twelve knobs which are placed like a corona round the entrance
1<> the orifice of invagination, and lie close together so as to greatly contract the opening.

In order to understand the construction of the upper part, it is necessary to open up
the animal longitudinally, then we see that it extends about 1 cm. inside the animal ; it
is covered with twelve strongly projecting sharp-edged longitudinal ridges, which begin
at the twelve knobs, become higher as they run downwards (upwards in the natural
position), till each of them ends in a nose-like projection. This projection is again
divided by a longitudinal furrow into a larger and a smaller process. The ridges and
their bifurcated ends are extremely smooth, very soft, and of a whitish colour. They
consist, however, only of connective tissue, like the rest of the wall.

The varied aspect of the surface of the body is caused by the varying character of the
epithelium ; on the invaginated part of the wall (PL VI. fig. 5) it is a ciliated cylindrical
epithelium, such as we find in most Actinias ; in the other parts it is without cilia, but
instead of cilia is covered with a deposit, which may be divided into two layers. One of
these (PL VIII. fig. 1) is an irregular, fibrous cuticle, which is stained an intense red by
carmine, the other is a mucous layer permeated by foreign bodies, lying outside the cuticle.

The mesoderm consists of extremely fine fibrillas which cross one another in all
directions, so that it appears as a finely granulated mass in transverse section. It is
partially laid in strata parallel to the surface; in it there are small roundish concrements,
which are strongly coloured by carmine, and the structure of which recalls that of granules
of starch ; they are made up of indistinct concentric layers, frequently appear in section
like a figure Q, and are limited to the superficial layer of the mesoderm.

The existence of a strong circular muscle, which is indeed easily discovered, might be
inferred merely from the high degree of contraction. It is mesodermal, and the chief bulk
of it lies in the invaginated section of the wall, where it begins close to the commence-
ment of the oral disk, or, to speak more accurately, to the origin of the tentacles (PL VI.
fig. 5) ; it extends a considerable way into the outer section of the wall, into which it
gradually passes. It is separated from the endoderm by a broad layer of connective
substance, so that it lies nearer to the ectoderm than to its place of origin, and consists
of numerous very small bundles of fibrillar grouped together into bundles of the second
order (PL VIII. fig. 10). The latter are usually flattened, and in transverse section show-
bands lying perpendicular to the surface of the endoderm.

The comportment of the oral disk is the same as that formerly described in Gcdliactis
'parasitica. The muscular fibres are still chiefly ectodermal, and the lamella is not
thickly pleated, though at the same time single fibrillse and groups of fibrillar have
passed into the mesoderm. The boundary line between the mesoderm and the ectoderm
is therefore indistinct as in Calliactis.

REPORT ON THE ACTINIARIA. 83

The tentacles are small, broad at the base, and pointed towards the end ; they are
placed in three rows, as they probably alternate in the first and second row, whilst the
third row contains double the number. Their longitudinal muscles are ectodermal and only
slightly pleated.

The oesophagus and the two oesophageal grooves are of a deep brown-violet colour
even in the spirit material ; this is caused by fine pigment granules deposited in the
ectodermal epithelium.

There are altogether four cycles of septa. Only the septa of the first order arc
perfect, all the others are imperfect, but, on the other hand, the latter only bear (male)
reproductive organs, whilst the former are sterile.

The muscles of the septa are very strong, as Jourdan already observed in Phcllia
elongata ; in the first three cycles especially the longitudinal muscles form mushroom-
shaped projections in the middle of each septum, which show the debcate, dendritic
figures of a repeatedly folded muscular lamella in transverse section. The transverse
muscular layer is also thickly pleated, so that it is doubly remarkable that I could find
no trace of a parietobasilar muscle even in sections.

All the septa seem to bear acontia ; these are extremely fine, and lie coiled in the
lowest section of the gastric space. I was able to make them out distinctly in transverse
section, but, on the other hand, I could not find any openings in the wall.

The directive septa were fused by the free margins, nearly their entire length below
the oesophagus (PI. VIII. fig. 2). I only examined one pair of them, as I wished to
destroy the single specimen taken by the Challenger as little as possible. The longi-
tudinal muscles of one septum pass continuously into the longitudinal muscles of the
other, whilst a mesenteric filament is wanting at the point of junction. The filament
is confined to the short space lying between the lower margin of the oesophagus and the
beginning of the fusion, where it is coiled in numerous curves. I shall leave it an open
question whether it be correct to speak of a fusion of the free margins, as I have done for
the sake of simplicity, or whether the union of the two septa does not rather represent a
more primitive condition. I wish, however, to draw attention to one fact which seems to
favour the latter view, and which I have formerly noticed repeatedly, viz., that in the
young Actiniae we frequently find the newly-formed septa of a pair connected together
in the same manner as in the principal septa of Phellia and the secondary septa of
Tealia hunodiformis, figured by me in Plate VIII. From this it would appear that
separation takes place later on, as at a later period all the septa have free margins set
with mesenteric filaments.

Bunodes, Gosse.

Sagartidse (?) with numerous papillae on the wall, which are placed in reo-ular
longitudinal rows, corresponding to the intraseptal spaces.

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

When Gosse erected his genus Bunodes (Trans. Linn. Soc., vol. xxi. p. 274, 1855),
he included in it all Actiniae furnished with a knobbed surface. Later, he limited this
name to those Actiniae on the walls of which the papillae are arranged in regular, longi-
tudinal rows (Ann. and Mag. Nat. Hist., ser. iii. vol. i. p. 417, 1858). In both instances,
however, he laid it down as a rule that there should be no acontia, and the same definition
of the genus was accepted by Verrill (Trans. Connect. Acad., vol. i. p. 467), by Klunzinger
(Korrallthiere, i. p. 77), and by Jourdan (Annales des Scienc. Nat. Zool., ser. vi. t. x. p. 84,
1879-80). Gosse himself, however, changed his views afterwards, for, in his Actinologia
Britannica, he described Bunodes coronata as a form in which he had once observed acontia.

Among the Challenger material I found one true representative of the Sagartidae,
the external appearance of which justified its being placed in the genus Bunodes. I have
determined it as Bunodes minuta, as I consider it quite possible that the acontia have
hitherto been overlooked in the species of the genus Bunodes. If this view be erroneous,
it would be necessary to erect a new genus for Bunodes minuta and Bunodes coronata.

Bunodes minuta, n. sp. (PL II. fig. 12).

Wall covered with alternate rows of larger and smaller papillae, which are confined to
the upper half of the body ; tentacles long and pointed, arranged in two circles, the outer
circle much smaller than the inner.

Habitat.— Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E. Depth,
1600 fathoms. One specimen.

Dimensions. — Height and breadth, 1 cm.

The general appearance of the small new species of Bunodes, which I shall describe
as Bunodes minuta from a single specimen found among the Challenger material, recall»
that of Paractis excavata At first sight the body seems as broad as high (fig. 12, a),
but if we cut open the animal (fig. 12, b) we see that the oral disk extends deep down
into the body, so that there is but a little distance between the pedal disk and the
periphery of the mouth. The diameter of the oral disk is therefore essentially greater
than the breadth of the body given above.

The upper section of the wall is brownish, the lower part whitish and covered with
small papillae, which are arranged in from thirty to forty rows. Each row begins at the
upper margin of the wall, and reaches half-way down the animal ; the papillae are small
at first and increase in size downwards ; they comport themselves differently, however,
in the different rows, as rows with large papillae and rows with small papillae alternate
irregularly. The same conditions therefore recur in Bunodes minuta, which exist in
Bunodes coronata, a fact of special interest, as they are the only two species of Bunodes
in which acontia have as yet been found (Gosse, Actinologia Britannica, p. 204).

Histologically, I find that the papillae are formed of connective substance only, and
have therefore come to an entirely different conclusion from Jourdan, who declares them

REPORT ON THE ACTINIARIA. 85

to be products of the ectoderm (Annal. des Scienc. Nat., ser. vi. t. x. p. 78, 1879—80).
According to Jourdan, the papillae which he terms " verrues glandulaires " have arisen
from the epithelium pushing its way like glands into the supporting substance, and be-
coming wholly or nearly detached into epithelial islands. The author gives these epithelial
cords as the first stage of development in longitudinal section, the detached epithelial
islands in transverse section. I have obtained figures exactly similiar to those given by
Jourdan, and am justified in the view that the constitution of the wall agrees in both
species of Bunodes, but am also justified in maintaining that Jourdan's view is erroneous.
These epithelial growths are linings of the depressions and furrows running on the surface,
of the wall ; they become deeply pleated during contraction, and may look like detached
epithelial islands in transverse section, whilst in longitudinal section they may be taken for
mere epithelial folds. In order to be quite certain, I made sections parallel to the surface
and also examined single papillae in transverse section ; in the former we have invariably
islands of connective tissue, the transverse sections of the papillae, surrounded by an
epithelial net-work but without glandular ducts ; in the latter the papillae proved to be
solid growths of the connective substance. From these observations I have already, in
the introduction, declared myself to be against the acceptation of the term " verrues
glandulaires."

The circular muscle is entirely enclosed in the mesoderm, which, however, is only
slightly thickened by it ; the bulk of it extends longitudinally, is almost equal in breadth
the whole way along, and is separated from the endoderm by a narrow layer of connective
substance, from the ectoderm by a somewhat broader layer. The roundish bundles of
fibrillse, which merely consist of a few strong muscular fibrillar, are divided by processes of
connective substance into larger and smaller groups ; this is beautifully seen in the upper
part of the muscle, whilst there is a preponderance of small, irregularly distributed
bundles in the lower part.

The muscles of the oral disk are divided into radial bands corresponding to the septa ;
they lie as a thickly folded layer in the ectoderm, like the longitudinal muscles of the
tentacles. Seventy relatively long, filamentous tentacles lie on the margin of the oral
disk ; they run out into a fine point, and project above the surface even in the contracted
animal. The outer tentacles are decidedly smaller than the inner.

In order to observe the septa properly I cut out a quadrant of the body which I made
into transverse sections. From these it was plain that the directive septa running towards
the oesophageal grooves alone were perfect, and did not bear reproductive organs, whdst
all the other septa, not even excepting the principal septa, remain imperfect, and are
amply furnished with reproductive organs (testes). The differentiation of the septa into
muscular septa and reproductive septa, which is present in all Sagartidae, extends in
Bunodes minuta to the more limited circle of the principal septa.

If I may draw a conclusion from a small part of a single specimen, the formation of the

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

septa is very irregular, and seems to proceed more quickly near the directive septa.
I have found that septa of the sixth and seventh orders are present in the interseptal
space contiguous to the directive septa, whilst septa even of the fifth order are wanting
in other parts. This assertion must of course be accepted with reserve, as the septa are
so irregularly constituted that it is difficult to determine to which order a septum
belongs.

I have found the acontia only in transverse section ; they are oval filaments, dotted
with nematocysts, quite small, and by no means numerous. This confirms my view that
the acontia have hitherto been overlooked in the other species of Bunodes.

Family, Amphianthid^e, Hertwig.

Hexactinite, which are attached to the axial skeletons of Gorgonidse with shortened
sagittal and elongated transverse axis; tranverse axis lying parallel to the axial skeleton
of the Gorgonia ; circular muscle mesodermal ; the principal septa only perfect and sterile.

Under the names Actinia abyssicola and Actinia gelatinosa, Moseley described two
Actiniae from the Challenger material, which agree in being attached to the stems of
Gorgonics which they clasp with their base. I was only able to examine the Actinia
abyssicola, as Actinia gelatinosa was not among the spirit specimens sent to me ; on the
other hand, I found two other new forms among the specimens, which resemble the two
species determined by Moseley both in their form and mode of life.

All these forms differ so decidedly from Actinia mesembryanthemum that I have not
only separated them generically but united them into a new family, the Amphianthidae.
Closer examination shows that the mode in which they attach themselves has influenced
their organization in a very important and uniform manner. All the Amphianthidae are
elongated, corresponding to the form of the body to which they are attached, and
placed in such a way that their transverse axis is greatly prolonged and runs in the
same direction as the longitudinal axis of the Gorgonia, whdst their sagittal axis is very
much shortened, and crosses the skeletal axis at right angles. The oesophagus
consequently differs from that of other Actinise, as it is either round or even fissure-
shaped in a transverse direction (PI. III. fig. 7, a), and its oesophageal grooves lie so near
one another that they almost touch (PI. II. fig. 13).

The internal anatomy recalls that of the Sagartidae. The six pairs of principal septa
are sterile and alone reach the oesophagus ; their interlying interseptal spaces have been
modified by the elongation of the form in such a way that the four spaces belonging to
the broad sides are more extensive than those belonging to the narrow sides. I was not
able to make out any acontia. The circular muscle is powerful and Hes in the mesoderm.

Two species already described by other naturalists, Actinia s. Catherines and
Gephyra clohrnii probably belong to the family Amphianthidae. The former, which
was described and figured by Lesson (Voyage de la Coqmlle, Zoo!., tome ii. part ii.

REPORT OX THE ACTINIARIA. 87

2, p. 74; Zoophytes, pi. ii. fig. 2), is certainly attached to a smooth underlying substance,
but is, nevertheless, greatly elongated in one direction, so that, if we may judge from the
drawing of it, even the corona of tentacles is divided into a right and a left half. On the
other hand, Gephtjra dohruii, our knowledge of which we owe to G. v. Koch (Zur Phylo-
genie der Antipatharia. Morphol. Jahrb., Bd. iv., Suppl., p. 78, 1878), settles like a true
Amphianthid on the axis of his elongata. The animals either live singly or are united
by basal processes into a colony ; they are fastened to the axis by a cuticular mass secreted
by the pedal disk. The author has unfortunately given no details as to the position of
the oral fissure with respect to the axis of the Isis and the constitution of the septa and
(esophageal grooves.

G. v. Koch considers the Gcjrfii/va as transition forms between the Actiniaria and the
Antipatharia; he assumes that Actiniae settled upon cylindrical bodies and secreted a
horny mass by which they attached themselves, that later, from want of a foreign axis,
they originated a proper axial skeleton by richer secretion of the adhesive mass, and
moreover became branched by forming colonies. The correctness of this view is con-
firmed by the few remarks made by v. Koch on the structure of AntipatJies larix. The
body is elongated in the direction of the skeletal axis, and the transverse axis of the
animal thereby appears lengthened, whilst the sagittal axis is shortened. This I conclude
from the position of the mouth and the septa ; the former is either circular or fissure-
shaped ; if fissure-shaped, it crosses the longitudinal axis of the animal. The different
direction of the longitudinal axis of the body, and the oral fissure is very striking, but can
be easily understood if we assume that the oral fissure has maintained its original exten-
sion in a sagittal direction whilst the body is prolonged in a transverse direction. We
must therefore look for the directive septa on the long sides of the body. In fact, we
find there two pans of septa, which correspond to the oral angles, are sterile, and conse-
quently comport themselves like directive septa, whdst the two remaining pairs, lying
in the prolonged transverse axis, bear reproductive organs, and are therefore best termed
accessory septa.

It is therefore most probable that the Amphianthidse bring about the transformation
of the Actiniaria to the Antipatharia. A more detailed study of the Antipatharia is
however necessary before this view can be fully accepted; above all, it must be deter-
mined whether the paired arrangement of the septa and the presence of the directive
septa can be demonstrated in the Antipatharia, and whether the sagittal and the trans-
verse axes are directed in the same manner as in the Amphianthidse.

Stephanactis, n. gen.
Amphiantidte with firm wall, divided by a circular swelling into an upper and a lower
section ; tentacles numerous, arranged in several rows, decreasing in size from within
outwards.

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

Stephanactis tuberculata, n. sp. (PI. III. fig. 7).

Upper part of the wall covered with larger and smaller knobs, thickly compacted
together, lower part smooth ; tentacles in four to five alternating rows.

Habitat.— Station 232. May 12, 1875. Lat. 35° 11' N., long. 139° 28' E. Depth,
345 fathoms. One specimen.

Dimensions. — Height, 2 cm. Length of the pedal disk, 10 cm. ; length of the oral
disk, 3 "5 cm. ; breadth of the oral disk, 2 cm.

The single specimen of Stephanactis tuberculata, which I was able to examine, is
attached to the axis of a Virgularia, from which the soft cortical layer has been com-
pletely stripped as far as the Actinia extends ; the pedal disk encloses the axis so com-
pletely that the two margins are pressed together, without, however, becoming fused, and
so form a sheath about 10 cm. long. The wall first runs about 2 cm. close to the pedal
disk, it then forms a body about 2 cm. high, which, being in a contracted condition,
becomes much smaller at the upper end ; the body appears fusiform when seen from the
oral side (fig. 7, a).

A thick circular swelling, running near the upper margin, divides the wall into a smaller
upper and a larger lower portion. The former is slightly inverted as in the genus Phellia,
and may be completely overlooked from the outside. It is covered with numerous knobs,
which lie thickly compacted, smaller and larger intermixed. The smaller are usually
rounded spheroidally, whilst the larger stand out as nose-like projections above the level
of the smaller ; they may be divided into two by shallow furrows.

The lower section of the wall is essentially smooth, as the transverse and oblkpie
wrinkles and furrows are merely caused by contraction. A more pronounced groove
extends on either side in a longitudinal direction, downwards from the circular swelling
at an equal distance from the two ends of the body (fig. 7). Four small knobs, in the
upper surface of which I could make out a little depression with a magnifying glass,
lie at the bottom of each groove. As I proved by means of transverse sections, these
depressions are the openings of fine canals, which pierce the wall, and form communica-
tions between the surrounding medium and the directive intraseptal spaces which lie
opposite to them ; they may be fitly compared to the cinclides of the genus Calliactis.

The circular muscle lies in the knobbed upper part of the wall, and extends downwards
as far as the circular swelling. It occupies nearly the entire thickness of the mesoderm,
which however it does not greatly increase ; in transverse section it is elongated, nearly of
ecuial breadth throughout, and is only reduced a little in size towards the lower end. The
bundles of fibrillse are very small, and distributed with tolerable regularity in the
fundamental substance, so that we can hardly observe any arrangement into larger or
smaller groups.

Though the sphincter is tolerably strongly contracted, we can make a partial survey of
the oral disk. It bears more than a hundred tentacles, placed in from four to five

REPORT ON THE ACTINIAPJA. 89

indistinctly denned rows. The tentacles of the innermost row are short, but broad at the
base, powerful and compressed; towards the outside the tentacles become smaller and
more slender. Indistinct radial furrows, caused by the distribution of the muscles, run
from the corona of tentacles to the oral opening. The muscles consist of tough, ecto-
dermal fibrilhe, the lamella made up of which lies thickly folded both in the oral disk
and in the tentacles.

The oral opening is elongated to an oval in the same direction as the whole body of
the animal, and from analogy to other Actiniae we might expect to find the oesophageal
grooves at the ends of the oval. In this case, however, they lie exactly in the middle of
the two broad sides and in the contracted animal so near that they almost touch. If we
cut out the part in question (fig. 7, h) we see that the oesophageal grooves are very broad
and reach far down, whilst the remaining irregularly pleated part of the oesophagus only
hangs down a little way into the stomach.

Except the two pairs of directive septa, which are attached to the oesophageal grooves,
the other four pairs of principal septa only are perfect, whilst all the secondary septa
terminate on the oral disk. The former are sterile, whilst the latter bear the repro-
ductive organs, which were testes in the specimen examined. There are large marginal
stomata in the septa, and in addition to these perioral stomata in the perfect principal
septa.

I endeavoured to discover the mode of arrangement of the septa by cutting out two
sextants contiguous to the directive septa and making them into transverse sections. I
found extremely irregular conditions, and in spite of all my trouble I am unable to
explain them with any certainty. Five pairs of septa of considerable strength be in
each interseptal space, but as they were equal to one another I wras not able to determine
their various ages from the difference in size. I am therefore undecided between two
opinions ; either the pairs of septa of the second order are doubled and three pairs of
septa of the third order are present, or else there is only one pair of septa of the second
order developed and the pairs of septa of the third order have undergone duplication.

In the interseptal spaces of the third order I found either only a single pair of the
fourth order or two pairs of the fourth order ; so that duplication seems also to have
partially taken place here.

It would be interesting to examine the sextants occupying the narrow side of the body
in order to see whether the arrangement of the septa is more regular in them. I refrained
from this, however, in order not to injure the single specimen of the species. We may,
however, certainly assume that the irregular development of the septa is the consequence
of the elongation of the body, and this is shown by the partial duplication of their number.
There would be nothing remarkable in such duplication, since the interseptal spaces
belonging to the broad sides are abnormally extended.

(ZOOL. CHALL. EXP. PART XV. — 1882.) P 12

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

Stephanactis abyssicola (PI. II. fig. 13).

Actinia abyssicola, Moseley, Trans. Linn. Soc, ser. ii., Zool., voL i. p. 297, pi. xlv. fig. 5.

Both parts of the wall smooth ; circular swelling distinctly defined ; tentacles in
two alternating circles.

Habitat.— Station 46. May 6, 1873. Lat. 40° 17' N., long. 60° 48' W. Depth,
1350 fathoms. Two specimens.

Dimensions. — Length, 3 '5 cm. ; height, 0*5 cm.

Colour. — (Determined by Moseley in the fresh condition), the part inside the circular
swelling a beautiful rose-red with a few darker radial streaks ; the remainder of the wall
reddish-yellow and paler, especially the circular swelling ; oral disk rose-red with paler
tentacles.

Of the two specimens of Stephanactis abyssicola, one was so much destroyed as to be
of no use for anatomical examination, and I did not wish to cut up the other as it was the
only well-preserved specimen of the species. Stephanactis abyssicola is clearly so closely
allied to Stephanactis tuberculata that I deem a more detailed anatomical study
unnecessary, and therefore confine myself to the description of its external appearance.

The body is elongated like that of Stephanactis tuberculata, but not prolonged into a
process at either end. The pedal disk enclosed the stem of a Mopsea so completely that
its margins were firmly joined on the lower side. The line of union is slightly undulated,
and the insertions of from ninety to one hundred septa, which he more closely compacted
at the two ends of the body, shine through beside it. The spaces between the septa
are larger towards the broad sides, but become narrower again towards the middle of the
broad sides.

The circular swelling, which Moseley erroneously terms the muscular sweding, is,
however, distinctly defined on either side. A small depression, in which rises a papilla,
lies on either side close under the circular swelling in the middle of the broad side,
resembbng those which we have met with in the same position, but in larger number, in
Stephanactis tuberculata. Otherwise, the wall is smooth, both in the portion lying
inside the circular furrow and that lying outside. It is incompletely contracted, so that
the oral disk, the oral opening, and part of the points of the tentacles are visible. As
the oesophageal grooves plainly occupy the middle between the two ends of the oval oral
fissure, it may be again safely assumed that the elongation of the body has taken place in
the direction of the transverse axis. Numerous small tentacles (sixty according to
Moseley) lie in a double row on the margin of the oral disk.

Stephanactis abyssicola is distinguished from Stephanactis tuberculata by its smaller
size, by the absence of knobs on the upper part of the wall, and by the lesser number of
cinclidal papillae. These are all differences, however, which may possibly arise from
difference of age, and it is quite likely that the two species might require to be united, if

REPORT ON THE ACTINIARIA. 91

we were able to examine a larger number of specimens. In this case, the species would
keep the older name of Steplianactis ahyssicola.

AmjJdanthus, n. gen.

Amphianthidse with a firm wall, which is covered with fine papillae but not divided
into two sections by a circular swelling.

Arnphianthus bathybium (PI. III. fig 11).

Upper section of the wall furnished with twenty-four longitudinal furrows, which
disappear as they run downwards, and covered with Arery small papilla?, mostly grouped
in transverse rows.

Habitat.— Station 241. June 23, 1875. Lat. 35° 41' N., long. 157° 42' E. Depth,
2300 fathoms. One specimen.

Dimensions. — Length, 4 cm. ; height, nearly 1 cm.

I have placed here beside the Stephanactis a small Actinia of which a single specimen
was dredged from a great depth. It agrees with the genus Stephanactis in having an
elongated form, and in being attached to a cylindrical foreign body. I was unfortunately
unable to determine whether or not the internal anatomy also agrees, as the septa were so
badly preserved that, in examining the piece, in which, from analogy to the forms in
question, I expected to find the directive septa, I was unable to arrive at any definite
results, even by transverse sections. In what follows I shall, therefore, merely give a
short description of the form and of the surface of the body.

The Actinia was firmly attached by its base round the stem of a Gorgonia unknown to
me, so that the margins of the pedal disk clasped one another by alternating indentations
like the notched margins of many bivalve shells (fig. 11, b). The insertions of from
ninety to one hundred septa appearing through the disk may be followed as white lines
proceeding a little way from the margins. At first sight the upper part of the wall seems
smooth, but under a tolerably strong magnifying glass we see that it is covered with
numerous very fine knobs, which look like the papules of an exanthema, and are arranged
in transverse rows (fig. 11, a), which lie at tolerably regular distances from one another,
and are separated by shallow furrows. The latter are crossed by twenty-four longitudinal
furrows, which are most distinct at the upper margin of the wall, but become shallower
before they reach its middle portion.

The wall is so strongly contracted at the upper end, that the oral disk is completely
covered ; in correspondence with which we find in longitudinal sections a circular muscle
of considerable size, having the same form as the circular muscle of Stephanactis.
I only observed these differences, viz., that the bundles of muscles are stronger, more
numerous, and more thickly compacted.

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

Family, Ilyanthidse, Gosse, pro parte.

Hexactinise, having the aboral end of the body rounded ; without pedal disk.
As I include in the family of the Ilyanthidse only those forms which have the septal
arrangement of the Hexactinise, I define it in a much more limited sense than Gosse
(Actinologia Britannica, p. 227) or even Verrill (Memoirs Boston Soc, vol. i. p. 26).
Verrill has detached the Cerianthidse only, but left the Edwardsias in the family, while
Allmann (Quart. Jour. Micr. Sci., new ser., vol. xii. p. 394), my brother and myself
(Actinien, p. 124), and Angelo Andres (Mittheilungen der Zool. Stat, zu Neaped, Bd. ii.
p. 123) have most clearly pointed out that the latter also ought to be separated. I
am of the opinion that even excluding the Edwardsise does not free the family from
foreign elements, for it is not at all likely that Halcampa albida and Halcampa producta
with twenty tentacles, Halcampa microps with sixteen tentacles, &c, conform to the
hexamerous type of arrangement of the tentacles.

By the absence of the pedal disk the Ilyanthidse form a transition to the tribe
Edwardsiae, on account of which I have placed them at the end of the Hexactinise ;
in their internal anatomy they are also allied to the Edwardsise. Halcampa clavus,
especially, which I am now about to describe, is so clearly an intermediate form that I was
for long dubious whether I should treat of it under the Edwardsize or the Hexactinias.

Halcampa, Gosse.

Ilyanthidse with elongated, vermiform body ; without sharply defined circular muscle ;
the posterior end may be distended into a vesicle ; oesophageal grooves indistinct or
wanting.

In all systematic descriptions of the Ilyanthidse published by former authors, the
genera Edwardsia and Halcampa are placed very close together ; according to Gosse,
they are only distinguished from one another by the facts, that the middle part of the
body in Edwardsia is surrounded by a sheath, an " epidermis," which is wanting in
Halcampa, and that the body is divided into three sections, the " capitulum," the
'•' scapus," and the "physa." Angelo Andres (I. c, p. 137) has recently made use of a
much more important anatomical character, viz., the presence of only eight septa
(" octoseptazione ") in Edwardsia, whde there are always at least twelve septa in
Halcampa. I only attach importance to the different arrangement of the septa, and
therefore will place forms with tripartite wall in the genus Halcampa, provided only
that they be true Hexactinise.

Halcampa clavus (PI. III. figs. 1, 4, 10 ; PL XII. figs. 8, 9, 11 ; PI. XIII. figs. 2,

. 4"7)-
Actinia clavus, Quoy et Gaymard, Voyage de 1' Astrolabe, Zoologie, iv. p. 150, pi. x. figs. 6-11, 1833.

Euanthus clavus, Milne-Edwards, Histoire des Corall., torn. i. p. 284.

REPORT ON THE ACTINTARIA. 93

Willi smooth, with twelve longitudinal furrows, and numerous small openings at the
posterior end of the body ; twelve tentacles, each with an adaxial and an abaxial longi-
tudinal furrow ; six pairs of septa.

Habitat. — Station 149. Off Kerguelen Islands, (a) January 9, 1874. Lat. 49° 16' S.,
long. 70° 12' E. Betsy Cove. Depth, 25 fathoms. Two specimens, (b) January
29, 1874. Christmas Harbour. Depth, 120 fathoms. One specimen.
Dimensions.— Height, 1*5-2 cm. ; breadth, 0"5-l cm.

The three specimens of Halcampa clavus which were sent me for examination varied
in size ; the two specimens taken in Betsy Cove were smaller than the one dredged up
in Christmas Harbour, and differed from it in habit of body. I believe, however, that
they should be referred to the same species, as the slight difference in size and form may
be the consequence of difference in age and degree of contraction, and their anatomical
constitution harmonizes completely. I examined the larger specimen, which was specially
well preserved, and one of the smaller ones.

The body is divided by two circular constrictions into three sections lying one behind
the other. The middle section, the scapus — if we adopt the nomenclature proposed by
Gosse for Edwardsia — in the largest individual was rather longer than the other two
sections taken together, and about 1 cm. broad (PI. III. figs. 1 and 4); it passed anteriorly
into a short neck-like part bearing the tentacles, the capitulum, and posteriorly into a
terminal part, 0'5 cm. long and broad, the physa. A cuticular deposit, like that covering
the scapus of the Edwardsice, did not exist, but on the other hand the wall is regularly
divided by twelve longitudinal furrows, which begin at the upper end between the
twelve tentacles and reach as far as the lower umbilically depressed end. The
longitudinal furrows are crossed by numerous transverse furrows, which, however, may be
caused by the strong contraction of the animal.

The wall is transparent and thin-membraned except at the points where the scapus
passes into the capitulum and the physa ; at the points mentioned it is greatly thickened
by increase of the supporting substance on the one hand and by numerous pleatings of
its endodermal and ectodermal surfaces on the other. The pleatings are caused by an
increase in the lamellse of the circular muscles, and may therefore be termed the upper and
lower sphincters, though they are by no means sharply defined. If we examine the wall
closely in longitudinal section we see that all over the inner side there is a layer of circular
fibres. The underlying supporting substance is divided into two layers, an inner, narrower,
nearly homogeneous layer, which stains a darker red in carmine, and an outer, broad,
fibrous layer, the two being separated by a sharp line. The inner layer is pleated at
tolerably regular intervals, into supporting folds, which run circularly, and project into
the gastric space ; they usually remain simple, and are rarely bifurcated at their
margins. Their surface is covered with numerous very fine, secondary folds, which
bear a layer of muscular fibrilla;, so that each circular fold appears finely pinnated

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

when seen in sections taken longitudinally through the wall. The two sphincters
are in fact merely local accumulations of these muscular rings, which are exceedingly
strongly developed (PI. XIII. fig. 2). The muscular rings rise much more than usual
above the surface of the wall, and seldom remain simple, but divide in transverse section
into two or three processes ; they may even divide repeatedly, and in this way give rise
in transverse section to the candelabra-like figure shown in Plate XIII. fig. 2. As the
upper sphincter lies at a little distance from the margin of the oral disk, it causes a deep
constriction of the wall and a corresponding external collar-like fold (PI. III. fig. 1, a).

The twelve tentacles are placed on the margin of the oral disk where the latter turns
over into the wall ; they are pointed in the smaller specimens, obtuse and compressed in
the larger. They are distinguished in both cases by two longitudinal furrows, one of
which runs on the adaxial side (fig. 1, b), the other on the abaxial (fig. 1, a). The
muscular system is ectodermal, and tolerably thickly pleated ; it has the same char-
acter on the oral disk, which is so small that the tentacles appear to be placed immediately
on the oral margin.

The oral opening (PL III. fig. 1, b) is circular and enclosed by twelve swellings. It
leads into a long similarly shaped oesophagus, which hangs down in the middle of the body;
the lumen of the oesophagus is narrow above and becomes wider below. I was not able
to find out oesophageal grooves, either in surface view after opening the animal (PL III.
fig. 1), or in transverse section (PL XIII. fig. 4) ; but, on the other hand, it is set with
twelve strongly-marked longitudinal ridges, corresponding to the insertions of the septa.
As the free margins of the longitudinal swellings are thickened, the intermediate furrows
are closed so as almost to form canals.

The septa are thin, veil-like lamellae, with a thick longitudinal muscle which lies
much nearer the oesophagus than the wall. The muscle begins in the lower part, the
physa, bulges out in the region of the scapus, becomes narrow again in the upper part of
the body, and ends on the oral disk not far from the oral opening (PL III. fig. 1). In
transverse section it forms a muscular mass of considerable size, which rests like a cushion
on the surface of the septum, but is marked off from it by a deep groove which runs
beneath its margin on either side (PL XIII. fig. 4). As to its structure it is a thickly
pleated portion of the longitudinal muscular layer, which, moreover, forms a small
longitudinal cord close to the wall. The rudiments of a parietobasilar muscle are also
found in a similar position on the side of the weakly developed transverse muscles.

The septa are placed at regular distances from one another, though at the same time they
are associated together in pairs. Two opposite pairs of septa have longitudinal muscles
on the sides turned from one another, whilst on either side there are two pairs with the
longitudinal muscles turned towards one another. This is, therefore, an arrangement of
the septa which must be taken as a starting point for all Hexactinise. Halcamjja clavtis
has only the principal septa, which, as we have already shown, are distinguished by a

REPORT ON THE ACTINIARIA. 95

peculiar mode of development, whilst the accessory septa, which are paired from the
beginning, are still wanting.

The constitution of the septa in Ilalcampa clavus shows further peculiarities worthy
of notice, which seem to me to indicate its relation to the Edwardsise. As I was preparing
a series of sections through the one half of the physa of the larger specimen, it struck me
that three septa (including the pair of directive septa) were not so strong as the other
septa, inasmuch as their longitudinal muscular cords became sooner indistinct (PI. XIII.
fig. 7). In the second smaller Halcanypa, in which I was able to make sections through
the entire body, four septa were somewhat smaller than the eight others ; and, finally,
Strcthill Wright has described a parasitic Ilalcampa living on Medusas {Halcampa fultoni) ,
in which we can distinguish four stronger and eight weaker septa (Ann. and Mag. Nat.
Hist., ser. iii. vol. viii. p. 133, 18G1). All this shows that an unequal development of the
septa, and, consequently, a difference in their morphological value, is not unusual in Ilal-
campa. If we assume that the eight stronger septa are homologous with the septa of
Edwardsia, whilst the four other septa are new formations, then the genus Ilalcampa
would present us with transition forms between the Edwardsise and the Hexactiniae.

I shall not discuss the point in question further, but I wish to draw particular
attention to the importance of a detailed investigation of the Ilyanthidae for a phylo-
genetic study of the Actiniaria. I am of opinion that an investigation of the position of
septa, extended not only over the mature animals, but also over the larvae, would
furnish us with very interesting explanations as to the manner in which the paired
arrangement of the septa has been developed among the Actiniaria. Of course a mere
enumeration of the septa would not suffice, but it would be necessary to lay down definite
characters for the determination of the septa newly formed in the Ilyanthidae, with special
reference to the distribution of the muscles and the relations of position depending
upon it.

Reproductive organs were present in all the septa; ovaries in the larger of the
two specimens examined, testes in the smaller ; they lay below the oesophagus, inwards
from the longitudinal muscles. The ovaries were admirably preserved, so that I availed
myself of the opportunity to make a more detailed examination of the origin of the ovicells
and the structure of the filamental apparatus. The youngest ova are again portions of the
epithelium (PI. XII. fig. 11), and become surrounded very gradually by the supporting
lamella ; if the latter be strongly coloured, we see from ova of considerable size, such as
that given in fig. 11, that they are not yet entirely surrounded by the supporting
lamella, but that the interior of the follicle of the ovum still communicates with the
epithelium by means of a wide, roundish opening. A fine hatching is visible on that
portion of the ovum which closes the opening as though fine filaments were present
on the surface ; these are either processes of the ovum itself, which serve to connect
it with the epithelium, or they are the bases of the epithelial cells. This point

9G THE VOYAGE OF II.M.S. CHALLENGER.

cannot be definitely determined after preservation in spirit, but would require material
preserved in osmic acid.

After the ovum has passed into the supporting lamella, it still reaches the bases of the
epithelial cells by means of a narrow process, the cells having undergone the modifica-
tions already described (fig. 8). The cells are fine filaments, with few granules, and
compressed into a body shaped like a gustatory bulb ; they are much more numerous than
in Corallimorphus.

The part of the filamental apparatus formed of epithelial cells lies originally in the
same plane as the opaque, granular, epithelial cells, but later, when the ova increase in
size, it occupies the bottom of a depression in the epithelium, surrounded by the neigh-
bouring cells which have increased in length. On the other hand, it never passes over into
the mesoderm, so that the filamental apparatus remains in a condition which leaves room
for further differentiation in Corallimoiyhus. On the larger ovicells there is a narrow
cortical layer which is distinguished from the central parts by a structure only indistinctly
preserved in spirit. Radial lines indicate, however, that the protoplasm has become divided
into small rod-shaped pieces.

Whilst acontia are wanting, the configuration of the mesenteric filaments is the same
as in other Actiniae. I was able to make out a marginal stoma by the help of transverse
sections in the upper part of the septa, but I could not determine whether a perioral
stoma exists or not.

After the septa are free from their reproductive organs, their mesenteric filaments,
and their stronger, specialized muscular cords, they still extend as far as the centre point
of the rounded posterior end of the body. Two of the septa are connected in such a way
as to form a partition wall separating the four septa on the one side from the six septa
on the other (PI. III. fig. 10). This arrangement precludes the existence of a central
posterior pore, but in place of it I found numerous eccentric openings, which are, however,
so small that they could not be perceived on the surface, even under a strong magnifying
glass. I observed them by making sections transversely through the posterior body-wall
of the larger animal, and parallel to the convex terminal surface of the smaller.

The openings are placed in a circular zone at a Httle distance from the centre point.
In sections parallel to the surface I found two of them in the same radius, one outside
the other, and I therefore presume that there are about twenty-four of them ; each radial
chamber probably containing two (PI. XIII. fig. 5). This point cannot, however, be easUy
determined from preserved material, as in such a case the wall is pleated, and also from
its convex curvature is not well adapted for making such sections.

If we prepare a series of transverse sections, we have a successive view of a large
number of openings, often two in the same transverse section, placed symmetrically left
and right from the middle ; from the relation of their positions to the septa, which can
also be seen in transverse section, we may assume that they are regularly distributed

EEPOET ON THE ACTINIAEIA. 97

over the different radial chambers (fig. 6). There is always a distinct hole in the
supporting lamella through which the ectodermal epithelium of the pedal disk sends a
cellular mass projecting like a mushroom towards the gastric space above the surface of the
endodermal epithelium. This epithelial mass completely closes the opening, but consists
of two layers of cells, firmly pressed together ; when these part asunder, which must be
the case when the posterior body-end of the animal becomes distended, an open canal is
formed in the epithelium, through which water can penetrate into the inside of the body.
Similar arrangements probably exist in Edwardsia ; the aboral section of this Actinia,
being likewise separated from the preceding by a constriction, can be alternately dis-
tended and contracted, and during this process the openings might be of great service.

Tribe II. Par actiniae.

Actiniaria with septa united in pairs. Septa of each pair furnished with transverse
muscular fibres on the sides turned from one another, and with longitudinal muscular
fibres on the sides turned towards one another, excepting the two pairs of directive
septa, which are opposite one another, and have longitudinal muscles on the sides turned
from one another, and transverse muscles on the sides turned towards one another.
Number of the septa not determined by the number six. Mouth fissure-shaped,
oesophagus with two oesophageal grooves and two oesophageal lappets.

I have separated two forms from the Hexactinise because the number of their antimeres
does not increase in multiples of six, and I have given them the name of " Paractinise "
because they resemble the Hexactinise in the most important points, and therefore
represent a parallel group. Above all, they are furnished with oesophageal grooves and
have septa arranged in pairs, of which two pairs corresponding to the oesophageal grooves
are placed opposite one another, have longitudinal muscles on the sides turned from one
another, and are therefore true directive septa. The tentacles have undergone retrograde
metamorphosis in both forms, which differ, however, so greatly from one another that I
consider them as the representatives of two different families.

Family, Sicyonid^:.

Sessile Paractinise with tetramerous arrangement of the septa ; circular muscle meso-
dermal ; tentacles transformed by retrograde metamorphosis into small knob-like stumps.

The most striking characteristic of the Sicyonidae — apart from the retrograde metamor-
phosis of the tentacles, which is also met with among the Hexactiniae — is the tetramerous
arrangement of the septa. Ha3ckel, as we know, sought in his Generelle Morpholooie
for soft-membraned ancestors of the fossil Tetracorallia, and believed he had found
one of their descendants in Cerianthus. Eecent works on the anatomy of Cerianthus

(ZOOL. CHALL. EXP. PART XV. — 1882.) P 13

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

have greatly lessened the probability of Hseckel's view being correct, as in the mature
animal the number of the septa is always even, but otherwise very variable. In
Sicyonis crassa, on the other hand, we have before us an animal in which the number
four is as persistent as the number six in the Hexactinia?, and which, moreover, has the
same paired arrangement of the septa as we meet with in the existing hexamerous
corals. It is therefore quite possible that the Sicyonidse and Tetracorallia may be closely
related.

Sicyonis, n. gen.

Sicyonicke, with discoid, flattened body, smooth wall, and alternating reproductive
septa and muscular septa.

Sicyonis crassa, n. sp. (PL IV. figs. 1-9).

Sixty-four wart-like tentacles placed in two alternating rows ; circular muscle weak ;
oral disk covered with numerous fine radial furrows.

Habitat.— Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E.
Depth, 1600 fathoms. One specimen.

Dimensions. — Height, 2 cm. Diameter of the pedal disk, 7 cm. ; of the oral disk,
9 cm.

The new species, which I have named Sicyonis crassa, is one of the most interesting
Actiniae dredged from great depths, both on account of the constitution of the tentacles
and of the arrangement of the septa. The body of the single sj^ecimen before me is cake-
shaped, as the transverse measurement of the pedal disk amounts to 7 cm., and that of
the oral disk to 9 cm., whilst the height only amounts to 2 cm. The height would,
however, certainly be greater in a natural state, as the animal had been very much com-
pressed in the packing.

The body is tolerably tough, more, however, from the thickness of its walls than from
the firmness of its tissue. The consistency of the latter is between that of cartilage and
of gelatinous tissue, and consists in all parts of the body of a homogeneous fundamental
substance enclosing numerous extremely small cells. The fundamental substance is also
traversed by numerous bundles of fibrilke, which become very distinct in preparations
stained with carmine. These bundles have a wavy course, and become connected from
time to time so as to form a reticulate framework. It was not possible to recognise the
natural colour of the animal.

The pedal disk (fig. 2) is marked by radial furrows ; a large number, more than 100,
begin at the margin, of which some reach the centre, whilst others do not extend so far.
Their course is irregularly waved and indented, and they correspond to the insertions of
the septa inside the animal.

REPORT ON THE ACTINIARIA. 00

The wall is small in height, and divided by a deep circular constriction into
an upper and a lower half (fig. 9) ; it appears, on the whole, smooth and only
furrowed irregularly on the surface in consecpience of the contraction of the
animal. The circular layer of fibres on the inside is very weak, both because the
separate fibrillse are very fine, and because the layer, formed by them, is only slightly
pleated. The circular muscle at the margin of the peristome is also insignificant ;
it lies immediately outside the tentacles, and produces about four or five narrow
circular swellings on the inside of the wall (fig. 1). It belongs completely to the
mesoderm, in which it is embedded as a very narrow streak, close under the endoderm.
The fibrillse, like those of the wall, are very fine, and united in small bundles which lie
close to one another, and are only separated by a small amount of intervening substance.
In transverse section, and under weak magnifying power, the muscular layer therefore
presents the appearance of a finely granulated mass.

The most important parts for the definition of the species are the oral disk and its
tentacles. The surface of the oral disk is marked by sixty-four radial furrows, which run
from the swollen margin of the mouth towards the bases of the tentacles, and are caused
by the attachments of the septa. They are, moreover, correlated with the arrangement
of the radial muscles, the layer of which always either becomes thinner or is completely
interrupted along a line below every furrow. The muscles are further mesodermal,
and so deeply embedded in the supporting lamella that they lie at equal distances from
the endodermal and the ectodermal surfaces. The separate fibrillae (fig. 6) are very
powerful, and the way in which they are grouped gives rise in transverse section to a
figure recalling the conditions known in the vertebrata. A few fibrillse are closely com-
pacted into a primitive bundle, several such bundles unite to form a secondary bundle
(fig. 8), and these again are united into larger groups. Each portion of the muscular
layer lying between two radial furrows contains several groups of such bundles.

There are sixty-four tentacles in all, distributed in two alternating circles. They
present a very unusual appearance, and are short knob-like elevations with a broad oval
base, and are pierced by a wide opening at the point. This gives them the appearance
of sucking cups, and on this account I have named the animal Sicyo7iis. The surface is
repeatedly pleated, and the interior also shows distinct circular folds (fig. 9). The walls
are very thick as far as a thin margin surrounding the terminal opening (fig. 3).
The radial muscular fibres of the oral disk make their way as longitudinal cords into the
tentacles, and have the same arrangement in the middle of the broad layer of connective
tissue as we have already discussed in the description of the oral disk. Examined in
transverse section (fig. 5) , they are deposited in a ring, which, however, is interrupted on
the side turned towards the margin of the peristome. There the layer of connective tissue
is very thick, but only contains a few isolated bundles of muscular fibrillaj. We see,
moreover, in longitudinal section (fig. 3), that the cords of muscular fibres do not make

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

their way into the thin margin surrounding the opening in the tentacle, but terminate
abruptly before they reach this point. The margin, therefore, merely consists of a
lamella of connective substance, covered by two layers of epithelium passing into one
another at the free edge.

On the oesophagus (fig. 4), the two oesophageal grooves at once strike the eye as deeply
incised furrows, bounded by broad folds and running zig-zag, as secondary transverse
folds project alternately left and right. The other longitudinal furrows, which run, ten
in number, on either side between the oesophageal grooves, are less distinct. From the
oral disk the oesophagus is separated by a thick lip-like swelling, divided into twenty-four
parts corresponding to the number of the longitudinal furrows of the oesophagus.

The number of the pairs of septa amounts in all to sixty-four. Sixteen of these are
of ecpial size and are inserted into the oesophagus ; alternating with these we find
sixteen other pairs only a little smaller, which end on the oral disk, but like the others
are purely muscular septa. On the other hand the last thirty-two pairs of septa, which
are equally distributed in the interspaces between the muscular septa, bear only the
reproductive organs and are furnished merely with a very thin muscular layer. There is
a very pronounced difference in size between the smallest muscular septa and the
reproductive septa, such as I have already described in Ophiodiscus. In Sicyonis also
the septa are merely thin-walled mesenteries for the reproductive organs, thick masses of
which (testes) occupy the free margin of the fold ; they only extend upwards to one-
third the height of the animal, and are entirely wanting in the angle between the wall
and the oral disk (fig. 9).

Fig. 9 shows the distribution of the muscles on the muscular septa. On the side
of the longitudinal muscles a single cord radiates like a fan towards the oesophagus and
the central parts of the oral disk ; on the side of the transverse muscles the parietobasilar
muscle extends half way up the wall, where it occasions the constriction already
mentioned. In the perfect septa a small opening lies in the neighbourhood of the mouth.
The muscular septa and genital septa are finally to be distinguished by the fact that
the former only bear mesenteric filaments.

Sicyonis crassa has another character in common with Ophiodiscus besides the
differentiation of the septa into reproductive and muscular, viz., the relation in which
the number of the pairs of sej)ta stands to the number of the tentacles.

In the majority of Actinise there are at least twice as many tentacles as there
are pairs of septa, so that each intraseptal and each interseptal sjiace has its own
special tentacle. In Sicyonis and Ophiodiscus there is an equal number of pairs of septa
and of tentacles ; the thirty-two intraseptal spaces of the muscular septa only have their
own special tentacles, whdst the other tentacles belong in common to the thirty-two
intraseptal spaces of the reproductive septa and the sixty-four adjacent interseptal
spaces. This also shows the rudimentary character of the reproductive septa, since they

REPORT ON THE ACTINIATUA. 101

arc of so little importance in the constitution of the body of the Actinia that their
appearance has not even been followed by an increase in the number of the tentacles.

Family, Polyopia, Hertwig.

Paractinise, without pedal disk, posterior end of the body round and saccular, with
aboral opening (?) ; tentacles transformed into stomidia by retrograde metamorphosis.

In earlier systems the Polyopidse would have been placed among the Ilyanthidse, to
which family, apart from the absence of tentacles, they bear a strong external resemblance.
It is quite possible that at some future time forms may be found which shall furnish a
closer link between our Polyopidse and the Edwardsise formerly described as Ilyanthidas ;
more especially as the Edwardsise occupy in some measure a central position in the midst
of the Actiniae, and send out lines of affinity in various directions. At present, however,
it is more convenient to separate the Edwardsise and the Polyopidse as the paired
o-rouping of the septa, which is so pronounced in the latter, is still wanting in the former.

Polyopis, n. gen.

Polyopidse with smooth wall, the surface having longitudinal furrows indicating the
position of the septa ; circular muscle wanting.

Polyopis striata (PI. II. fig. 11 ; PL XL figs. 1-12).

"Wall with thirty-six longitudinal lines ; oral disk with thirty-six strongly developed
radial swellings and thirty-six marginal stomidia arranged in a circle.

Habitat.— StutiovL 299. December 14, 1875. Lat. 33° 31' S., long. 74° 43' W.
Depth, 2160 fathoms. One specimen.

Dimensions. — Height, nearly 2 cm. ; breadth, 2 cm.

Colour. — (Determined from the spirit specimen) wall saffron-yellow, oral disk whitish,
oesophagus dark brown.

The small Actinia without tentacles, which I call Polyopis striata (677-/) = opening),
was probably sac-shaped during fife ; its rounded posterior end probably stuck in the
sand, whilst its broad anterior end formed by the oral disk projected freely. In conse-
quence of packing, the animal was pressed quite flat, the oral disk and oesophagus turned
out and very much injured, the septa consequently misplaced and torn. The difficulty of
examining the septa was increased by the fact that from the hardening by alcohol, the
septa had stuck together, and could not be easily separated by dissection. The
preservation of the tissue was satisfactory, especially that of the epithelium on the oral
disk, oesophagus, and septa.

The wall is of a delicate yellowish colour, which is contained in the endoderm, as the
ectoderm is rubbed off and the mesoderm colourless and transparent after the epithelium

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

is removed from the inside. The colour is caused by numerous small granules, which
completely fill the endodermal epithelial cells.

The lower end of the sac-shaped body, the aboral pole of the longitudinal axis, is
denoted by a small depression, which is equally visible on either side, and is caused, it
seems to me, by a microscopically small opening found at this spot (PI. XL fig. 11).
In order to settle this question by transverse sections, I cut out the portion of the wall
containing the opening, and laid it to stain in carmine, but unfortunately it got lost.

On the exterior in the periphery of the aboral depression there are six shallow, radial
furrows, which soon become less distinct as they run upwards. Instead of them, thirty-
six longitudinal streaks begin, the external signs of the origins of the septa, which run
at an equal distance from one another to the margin of the oral disk. The inside of
the wall is covered with a smooth layer of circular muscular fibres, which are never
compacted into a distinct sphincter, which explains why the upper end of the wall is not
contracted at all.

The structure of the oral disk, which projected like a proboscis in the animal examined,
requires a more detailed description. Thirty-six stomidia lie close to its peripheral
margin ; these are fine, longitudinal fissures enclosed by thickened lips, their greatest
diameter extending in a radial direction. Through the stomidia we see the inside of the
body, looking alternately into an intraseptal and an interseptal space ; they therefore
alternate with the septa which are inserted into the narrow portions of the oral disk, lying
between two stomidia. Sections perpendicular to the surface of the disk and parallel
to its margin through the region of the stomidia are, therefore, divided into as many
pieces as there are septa, and each piece consists of a septum and the section of the oral
disk belonging to it (PI. XL fig. 9).

Distinctly marked radial thickenings (PL II. fig. 11 ; PI. XL fig. 6), extending to close
upon the oral opening, proceed inwards from the stomidia. They are broad and shallow
in the middle of the oral disk, but rise towards the outside and towards the inside into
narrow comb-like ridges, the outer ridges being divided into two small folds. These
folds end near the stomidia and twist repeatedly during their course so as to produce
S-shaped figures. Each two contiguous folds enclose a fissure along which we can pass
a needle a little way into the interior of the corresponding radial thickening, which shows
that the inner part of the thickening is hollowed out by a radial invagination.

From the varying relations of the different parts of the oral disk the transverse
sections also present very different figures, according as they are made nearer to or
further from the oral margin. Fig. 7 gives a section corresponding to the line 8 in fig. 6.
The supporting lamella is thickened in the middle between each two septa and covered by a
repeatedly folded muscular layer. Inwards from this point, in the region of the line e, above
each radial chamber, the supporting lamella rises like a ridge which also bears a thickly
pleated muscular lamella, as shown in fig. 5. The section given in fig. 3, whose position

RETORT ON THE ACTIN1ARIA. 103

is determined by the line y, shows the same figure, but with this difference, that in this
case hollow spaces appear in the supporting lamella, which either lie as triangular gaps at
the bases of the ridges, or force themselves as fissures into the ridges themselves. These
hollow spaces, found in transverse section, correspond to the pouch-shaped invaginations,
which extend into the peripheral part of each radial swelling ; here and there I found
accumulations of cells in the spaces, — the remains of the epithelium lining them, which
unfortunately was badly preserved. In fig. 1 we have a transverse section taken through
the small folds at the beginning of the radial thickenings, along the line a. The
figures 1-3 show an irregular arrangement of the muscles, as they are sometimes
divided perpendicularly, sometimes obliquely, sometimes parallel to their direction.
This irregularity may be explained partly by the tortuous course taken by the beginning
of the radial swelling, partly by the fact that the muscular fibres, which originally
extended horizontally, have been slightly diverted from their straight direction by the
comb-like elevations of the supporting lamella.

The oesophagus was too much injured to allow of its constitution being determined
by means of dissection. I was able, however, to examine pieces of it, recognisable by
their brown-violet colour, in a series of sections, and to make out openings which lie under
the oral margin and lead into the radial chambers. It seemed to me that there wTas an
opening surrounded by a swollen margin between every two insertions of the septa (fig. 4).
The openings are not all of the same size, as many of them can be recognised in a whole
series of transverse sections as long fissures, whilst others are only visible in three to four
moderately thin successive sections. They can hardly be considered artificial produc-
tions, in the first place, because the surfaces of the epithelium of the two sides pass
evenly into one another at the margin of the opening, and secondly, on account
of the comportment of the muscular system. The oesophagus of Polyopis striata has
exceptionally ectodermal longitudinal muscular fibres, which are only apparent in thin
transverse sections, as they are extremely fine. The muscular layer is thickly pleated
at the rounded margins of the openings, so that it may here be regarded as a sphincter
capable of closing the opening.

The septa correspond to the longitudinal ridges on the surface of the wall, and are
therefore thirty-six in number ; they lie at perfectly equal distances from one another,
but are in pairs notwithstanding, as may be seen from the arrangement of the muscles.
Among them there are two pairs of directive septa (fig. 8) which are separated from
one another by eight pairs of ordinary septa. The latter vary very much in size,
although I was not able to observe' any arrangement in cycles of unequal value ; I
consider it most probable that we have here a tetramerous arrangement of the septa, but
that a pair of septa too many has been formed in one interspace on either side. Down-
wards the septa reach nearly as far as the aboral opening ; they are, however, of different
sizes, so as to present the figure given in fig. 11, /3.

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

The longitudinal muscles are slightly pleated, the transverse muscles not at all. There
is a special muscular cord on the same side as the transverse muscle, which extends close
to the wall, becomes broader as it runs downwards, and is homologous in position with the
parietobasilar muscle of other Actiniae. Further, it appears to me that all the septa
reach the oesophagus, are all furnished with reproductive organs (in the present instance
with testes), and have all a small perioral and a very large marginal opening (fig. 12).
Unfortunately I could not decide this point with any certainty, as only a few septa,
such as that given in fig. 1 2, could be dissected out ; most of them were sticking
together so that the mode in which the reproductive organs were distributed on the septa
was never clearly seen in transverse sections.

Tribe III. Monaule^e.

Actiniaria with paired septa, but with only one pair of directive septa.

The Monauleae form the third and last group in which the paired arrangement of the
septa is distinctly pronounced, and therefore come nearer to the Hexactinise and
Paractiniae than the Zoanthese and Cerianthese. It is remarkable that there is only one
pair of directive septa, a fact which may perhaps be explained by the obliteration of
the second pair.

From the absence of the second pair of directive septa, it follows that the body is
exactly bilaterally symmetrical, as it is divided into symmetrical halves by only one
divisional plane which runs through the intraseptal space of the directive septa. This
divisional plane passes through an interseptal space on the opposite side, and divides the
remaining pairs of septa equally, half lying on its right and half on its left. The whole
number of the pairs of septa is consequently unequal.

There is only one oesophageal groove, caused by the marked shortness of the directive
septa, and on account of this I have chosen the name Monauleaa (auXos, a groove or tube).
This groove was not very distinct, however, in transverse sections in the species examined ;
it would probably come out more clearly if looked at from the surface.

As I only know one species, it would be little to the purpose to give special diagnoses
for the family and genus. I shall therefore proceed at once to discuss the species.

Family, Monaulid^e, Hertwig.

Scytopliorus, n. gen.1

Scytophorus striatus, n. sp. (PI. III. fig. 6 ; PI. XIII. figs. 1, 3, 8).

Sessile Monaulidse with seven pairs of septa and fourteen longitudinal furrows on the

1 sxi;T£>?=leather.

REPORT ON THE ACTINIARIA. 105

\v;ill ; the Willi covered with a tough cuticle ; no circular muscle ; tentacles fourteen in
number, of medium size, arranged in a single circle.

Habitat.— Station 150. February 2, 1874. Lat. 52° 4' S., long. 71° 22' E. Depth,
150 fathoms. Two specimens.

Dimensions. — Height, 27 cm. ; breadth, 0"8 cm.

Colour. — (Determined from the spirit material) brownish-yellow.

The Actiniae without pedal disk and with rounded, aboral end mostly vary in the
arrangement of their septa from the type predominating in the whole section, as
was explained in the Introduction, but this is rarely the case with the sessile forms.
Scytoplt'irus striatus, which represents a new species, furnishes one of the few examples of
this variation which have come under my observation. I found two specimens of it
in the Challenger material, so that I was able to examine one of them thoroughly.

The body is very much elongated, and even in a state of contraction measures 2'7 cm.
in length, whilst it is only 0'8 cm. in breadth (PL III. fig. 6). The upper part of the
body is also inverted considerably (more than 0'5 cm.), as we see from the longitudinal
sections, a formation recalling Phellla peetinata, which has, however, an entirely different
structure. The surface is deeply incised by fourteen longitudinal furrows, which are the
more distinct because the surface is not soft as in the majority of Actiniae, but of a
leather-like consistency. This is owing to the presence of a strong cuticle, whose struc-
ture and relation to the underlying epithelium are best understood by transverse sections
(PL XIII. fig. 1).

The cuticle consists of two layers; (l), a superficial layer, which hardly stains at all
in carmine, but keeps its natural tint, to which is due the yellowish colour of the entire
animal ; and (2), a deeper layer which becomes an intense red when treated with this
reagent. The two layers are tolerably well defined, at some points even by a smooth
line. The stratification parallel to the surface, usually found in euticular secretions, can
be recognised in the lower deposit, and striation perpendicular to the surface is also
present at many points.

As the cuticle is of nearly equal thickness throughout, the longitudinal furrows of
the body, which show in transverse sections as deep indentations, are caused entirely by
the underlying epithelium and the supporting lamella. Both of these have an ecpial share
in causing the difference of level. The supporting lamella, a homogeneous fundamental
substance with scattered fusiform and branched cells, is very thick between each twro
furrows, and becomes thin below the indentations, and in the same wTay the epithelium
is unusually high between the furrows, but reduced to an almost imperceptible layer below
them. Where the epithelial cells are elongated they are separated from one another by
interspaces ; they are easily turn in preparing transverse sections, so that an artificial
hollow space arises between the cuticle and the supporting lamella.

The whole integument undergoes modification at numerous small, sharply defined

(ZOOL. CHALL. EXP. —PART XV. 1882.) P 14

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

spots. The supporting lamella projects like a papilla, and so reaches within a little
distance of the cuticle, and the epithelial cells are shortened correspondingly, but thickly
compacted ; their bases sink a little way into the supporting lamella, so that the contour
of the latter is notched, whilst at the same time they converge from their broader basis
towards a small spot of the cuticle which has a different appearance. The outer cuticular
layer pierces the inner layer, and extends to the top of the epithelial cells ; it thus forms
a conical projection, the central part of which is stained deep red by carmine, whilst the
periphery only preserves the yellower colour, so on the whole it shows in transverse
section the figure given in Plate XIII. fiV 1.

The cone of the outer cuticular layer is sometimes forced apart from the epithelium
by a thin stratum of the inner layer (fig. 8), but in this case the projection of the sup-
porting lamella is also wanting, and the epithelium has the same nature as usual.

I consider myself justified in explaining the conditions of structure of the cuticle
described above by the supposition that the cuticle undergoes a periodical change, a kind
of desquamation. The outer, yellow layer is the hardened cuticle ; this probably becomes
detached after a time, and is replaced by the inner cuticle, which stains so easily in
carmine. The circumscribed spots at which the yellow cuticle reaches the epithelium,
indicate the points at which it is more firmly attached to the surface of the body ; they
are the fastening nodes of the cuticle. The connection is gradually dissolved when the
yellow layer is forced apart by a fresh layer, even from the points of attachment to the
epithelium, in the manner just described.

The number of the fastening nodes in each transverse section is very large ; I counted
more than twenty in one section, including those in process of retrograde formation, all
on the whole of equal size. I also examined these peculiar formations in longitudinal
sections, and found the same figures as in transverse sections. I lay stress on this fact as
it proves that we are not dealing with long streaks.

The cuticle passes on to the inverted part of the wall, which in the contracted animal
projects downwards more than 0"5 cm. into the inside of the body ; it becomes thinner,
especially the superficial yellow layer.

A sharply defined circular muscle, such as I have described in most true Actinias, is
wanting in Scyt&phorus striatus ; instead of it, there is a peculiar differentiation of the
endodermal layer of muscular fibres. The layer of fibrillae is raised at short intervals into
folds, which are strengthened by the supporting substance, and produce branched figures
in transverse section. These bushes of muscles, which are covered by epithelium only,
project freely into the gastric space : they are most strongly developed in the upper
contracted and inverted section of the wall, where they are thickly branched and placed
closely together so as to replace the absent sphincter.

The ectodermal muscular fibres of the small oral disk and its, to all appearance, equally
small tentacles are very weak. The tentacles partly hang down into the oesophagus, are

EEPORT ON THE ACTINIARIA. 107

.also partly invaginated and retracted into the radial chambers in a way which is more
common among the Octocorallia than among the Hexacorallia ; in this case the sequence of
the layers is inverted in transverse sections, as the ectoderm is turned inwards, the endo-
derm outwards. There arc fourteen tentacles in all, each of them belonging to a radial
chamber.

On the oesophagus there are alternately eight longitudinal furrows and eight longi-
tudinal thickenings (PI. XIII. fig. 3), but little can be said about their constitution, as it
was plainly very much influenced by the contraction of the body. The deepest furrow
belongs to the interspace between the two directive septa, and may be regarded as an
oesophageal groove, even though I was not able to make out distinctly that it is covered by
a specially constituted epithelium. The transverse section of the oesophagus is roundish,
so that the flattening in the direction of the transverse axis, common to many Actiniae,
is wanting.

The septa are perfect without exception. They are thin lamellae bearing a very strong
muscular pennon, in the middle between the oesophagus and the wall. At this point the
longitudinal muscles are pleated in a sharply defined space nearly as thickly as in Tealia
bunodiformis ; besides these, a special cord of longitudinal muscles runs along the wall and
a rudimentary parietobasilar muscle lies in a similar position on the side of the transverse
muscles. A wide marginal stoma can be seen in transverse section between the two
longitudinal muscular cords.

The arrangement of the septa and the nature of the reproductive organs is of the highest
importance. Scytophorus striatus is the only Actinia known at present, in which the
number of the pairs of septa is unequal. This is not an accidental abnormality, as it is
caused by the absence of the second pair of directive septa and not by irregular growth of
the different parts of the body; this was clear from both the specimens under examination
as in each one wall was furnished with fourteen longitudinal furrows, corresponding exactly
to the fourteen septa, i.e., to the seven pairs. The existing pair of directive septa is only
distinguished from the other septa by the lamellae being shorter, on which account the wall
and the oesophagus approach nearest to one another at this point.

Scytophorus striatus belongs to the small number of Actiniae in which herma-
phroditism has been undeniably observed ; all the septa (the directive septa included)
bear ova in their upper sections, many of which were almost mature in the specimen
I examined, whilst the lower sections bear testes, though these were not so numerous as
the ovicells.

Tribe IV. Edwaedsle.

Actiniaria with eight septa ; among which are two pairs of directive septa, whilst the
remaining four septa are not paired ; all the septa furnished with reproductive organs ;
tentacles simple, usually more numerous than the septa.

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

Though Quatrefages, the discoverer of the Edwardsise (Mdmoire sur les Edwardsies,
nouveau genre de la famille des Actinies, Annales d. Sc. Nat. Zool., ser. ii. vol. xviii. p. 65,
1842), observed correctly that these Actinias have only eight septa, this important character
has not been sufficiently taken into account by most of the more recent writers. Milne-
Edwards and Gosse, who attach too much importance to the external characteristics of the
animal, had the absence of the pedal disk principally in view, and united the Edwardsise
with similar forms, Ilyanthus, Ccrianthus, &c, into the group of "Actinies pivotantes,"
or the family of the Ilyanthidas. Allman was the first to draw attention in a short notice
(Quart. Jour. Microsc. Sci., new ser., vol. xii. p. 394, 1872) to the detached position of
the Edwardsise, as he maintained them to be forms which, in the distribution of the
septa, more closely resemble the Alcyonaria and the extinct Tetracorallia. My brother
and I have shown more recently, from a thorough anatomical examination of the posi-
tion of the septa (Actinien, pp. 124 and 137), that the Edwardsise occupy an intermediate
position between the larvse of the Actinise with eight septa and the Alcyonaria. In the
Alcyonaria the septa are arranged in such a way, that reckoned from one end of the
sagittal axis, all the eight septa (four left and four right) bear longitudinal muscles on the
faces turned away from the starting point, whilst in the larvse Actinise the first four only
(two left and two right) have longitudinal muscles on the faces turned away, and the
four following on the faces turned towards the starting point, so that we find the same
relative arrangement, whichever end of the sagittal axis we start from. In the Edwardsise
we meet with the number six and two, i.e., considered from one fixed end of the sagittal
axis the first six septa are constituted like those of the Alcyonaria, the last two like
those of the Actinise. As in the Actinise the two pairs of septa jjlaced one at each end
of the oral fissure form the directive septa, two pairs of the directive septa are therefore
likewise present in the Edwardsise.

The correctness of the view, briefly recapitulated above, has been further corroborated
by a newly published work of Angelo Andres (Intorno all' Edwardsia Claparedii ; Mittheil.
der zoolog. Station zu Neapel, Bd. ii. p. 123) ; at the same time he pronounces in favour
of Allman's view that the Edwardsiaa may bear the same relation to the Tetracorallia as
the Actinise do to the skeleton-forming Hexacorallia. I do not agree with him on this
point. Apart from the number of the calcareous septa, the formation of the skeleton
is the same in the Hexacorallia and Tetracorallia, and it is therefore probable that similar
relations have existed among the soft parts of the body, and that the paired arrangement of
the septa was already developed in the Tetracorallia. As this is not the case in the
Edwardsise, I am inclined to seek for points of connection with the Rugosa in such forms
as Sicyonis crassa.

There was no true Edwardsia among the Challenger material ; but I was long
duboius as to whether it might not be expedient to include among them those forms in
which the paired arrangement and the number twelve of the septa begin to be developed,

REPORT ON THE ACTINIA RI A. 109

as for example IIulvm»]><i chicus. We may gather from this how closely the Edwardsiae
are connected by transition forms with the other Actiniae, and how advisable it is to discuss
them along with the latter, and to separate them from the Alcyonaria. From this point
of view the constitution of the tentacles is of great importance, as they in no way resemble
the tentacles of the Alcyonaria.

Tribe V. Zoanthe .e.

Actiniaria with numerous septa of two different kinds, smaller, imperfect, sterile micro-
septa, and larger perfect macrosepta furnished with reproductive organs and mesenteric
filaments ; the two kinds usually placed alternately, so that each pair is composed of a
larger and a smaller septum ; two pairs of directive septa at the ends of the sagittal axis,
one pair containing only macrosepta, the other only microsepta ; only one oesophageal
groove, corresponding to the larger directive septa ; animals usually forming colonies ; wall
usually traversed by ectodermal canals, and having the outside encrusted with foreign
bodies.

Zoologists differ very much in their opinions as to the limits and the definition of
the Zoanthese. Milne-Edwards (Hist. des. Corall., torn. i. p. 298) includes in this division
only colonial, sessile forms which increase by basal gemmation and have a leather-like
sheath hardened by encrustation with sand granules (faux polypieroide) ; Gosse agrees
with him (Actinologia Britannica, p. 295), but considers the encrustation with sand
granules as a secondary character. Most zoologists keep to the definition given by
Milne-Edwards and Gosse.

In 1856, Steenstrup described an Actinia under the name Sphenopus marsupialis,
which closely resembles the Zoanthese, but is distinguished from them by not forrn-
iug colonies and not being sessile. (Overs. Kongelige danske Videnskab. Selskabs
Forhand., p. 37, 1856). As Gray (Proc. Zool. Soc, p. 235, 1867) included this
Actinia among the Zoanthese, he set aside the characters used by Milne-Edwards, viz.,
the formation of colonies and the sessile mode of life, but without replacing them in the
diagnosis by new characters, which would be at once common to all Zoanthese, and dis-
tinctive from other Actiniaria. To what degree the sharp limitation of the Zoanthese
suffered from this may be seen from the fact that Gray included in this tribe the genera
lulwarilsiii, Hidnoiijxt, &c.

The discovery of Sj then opus led to difficulties as to the limitation of the Zoanthese
which were also not obviated by the fact that Verrill considered Sphenopus to be related to
the Edwardsise, to which it has certainly a strong external resemblance. But anatomically
Sphenopus agrees so thoroughly with the Zoanthese that it cannot be separated from
them. A study of the arrangement of the septa is the only possible means of discover-
ing distinctive characters for the division.

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

Angelo Andres (Quart. Jour. Micros. Sci., new ser., vol. xvii. p. 221, 1877) and my
brother and myself (Actinieu, p. 127) had already pointed out that the position of the
septa in the Zoanthese was regulated on an entirely different principle from that in other
Actiniaria, though G. v. Koch was the first to find out the true nature of it. He dis-
covered what I fully corroborate, that the septa present are of two different sizes (Morphol.
Jahrb., Bd. vi. p. 359, 1880). The larger or macrosepta only reach the oesophagus and
bear reproductive organs and mesenteric filaments, whilst the smaller or microsepta are
sterile and end on the oral disk ; the latter are not, as I formerly supposed, young septa
destined to be developed into larger, but are really rudimentary formations.

Both the larger and the smaller septa bear muscles on both sides : one side bears
longitudinal fibres, the layer of which is, however, only slightly pleated, the other side
bears fibres which rise obliquely, and are homologous with the transverse muscular fibres
of the other Actiniae, though they can easily be mistaken for longitudinal fibres in trans-
verse sections. There is here, therefore, a predisposition to the paired arrangement of the
septa, the existence of which was first recognised by G. v. Koch. Each pair consists of
a small and a large septum, having longitudinal muscles on the faces turned towards one
another (PI. XIV. fig. 2). The two pairs of directive septa form an exception, however,
as one pair of them, the ventral, contains large septa only, — the other pair, the dorsal,
only small septa ; in some Zoantheae, we must also except two pairs of ordinary septa
which lie right and left at a little distance from the small directive septa, and contain
macrosepta only (PI. XIV. fig. 3).

The manner in which the larger and smaller septa are distributed can be more
accurately determined if we start from the directive septa, and disregard provisionally
the grouping in pairs. In the Zoanthese, as in all Actinia?, two kinds of septa
alternate ; in the septa of the one system the muscles are disposed in the same way as
they are in the ventral pair of directive septa, whilst in the other system the case is
reversed, and they have the same disposition as they have in the dorsal pair of
directive septa. The septa which have the same arrangement of the muscles as the small
dorsal directive septa, viz., the dorsal septa, are likewise small, whilst the others, the
ventral septa, are strong ; it is only in the neighbourhood of the small directive septa
that the conditions are reversed as the dorsal septa are strong, and the ventral septa are
weak. We can therefore divide the ordinary pairs of septa into two different regions ;
in the one (the larger, or ventral region), the ventral septa of the single pairs are macro-
septa, and the dorsal septa are microsepta, whilst in the other (the dorsal region), the re-
verse is the case, and the dorsal septa are rnacrosepta. When all the pairs of septa are
equally developed, the two regions are bounded on either side by microsepta, but those
two microsepta are often wanting left and right, and in this way the pairs formed of
macrosepta alone, which have been already mentioned, are produced : these contain two
large dorsal septa of the dorsal region and two large ventral septa of the ventral region.

REFORT ON THE ACTINIARIA. Ill

The correlation, which exists in all Actiniaria between the oesophageal grooves and
the directive septa, is also shown in the Zoanthese, for there is only one oesophageal
groove, whilst the other is wanting, in correspondence with the rudimentary nature of
the directive septa to which it should belong. The tentacles, on the other hand, are
equally developed and placed in two circles, the inner of which belongs to the intra-
septul spaces, the outer to the interseptal spaces.

All the characters taken into account by former naturalists in the diagnosis of the
Zoanthese are of subordinate value when compared with the peculiar conditions just men-
tioned. The animals are united into colonies either by means of branched stolons or by
means of a broad basal plate, but there are also solitary forms which are embedded
with their rounded aboral ends in the sand like the Edwardsise. The entire surface of
the wall is often permeated with foreign bodies, though in many specimens such encrusta-
tions are wanting completely. Finally, the canals, which make their way from the
ectoderm into the wall, where they become branched and connected into plexuses, are
confined to certain forms only.

In the division of the Zoanthese I agree chiefly with Verrill, who divided the
species forming colonies into four genera ; Mwmmilifera, Zoanthus, Palythoa, and
Epizoanthus. The former two are distinguished from the latter by the absence of sand
encrustations. Zoanthus and Epizoanthus are distinguished from Mammilifera and
Palythoa by the fact that in the former two the polyps project plainly above the common
basis, whilst in the latter two they are united up to the free end by the basal coenen-
chyma. I have restricted the family Zoanthidse to those genera which form colonies,
and have associated all those which are solitary under the name Sphenopidse.

Family Zoanthid.e.

Zoanthese forming colonies ; the individuals of a colony connected with one another
by endodermal canals, which run out from the gastric space at the lower end of each
polyp.

Zoanthus, Cuvier, pro parte.

Zoanthus, Verrill.

Zoanthidse without sand encrustations and with a slightly developed coenenchyma
consisting either of a plexus of stolons or of a thin plate ; the single polyps projec
to a considerable height above the ccenenchyina.

Zoanthus, sp. (?) (PI. XIV. figs. 1-4 and 6).

Ha b itat. — Bermuda Islands.

Dimensions. — (Of the individual polyps): height, 0-1-1-3 cm. ; breadth, 0-1-0-4 cm.

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

Numerous species of the genus Zoanthus have been described which resemble one
another closely, and probably only differ slightly in their anatomy, so that the species
can only be determined by the colour, the number and arrangement of the tentacles, &c.
This is the reason why I have not given any specific name to the single specimen of the
genus Zoanthus found among the Challenger material, in which the colour of the body
and the nature of the tentacles could not be made out, and why I have refrained from
giving any diagnosis of species, as from insufficient knowledge of the closely allied species
it is impossible to determine which characteristics belong to the whole genus and which
to the individual species.

The colony, which was about 4 cm. long and 2 cm. broad, was firmly attached to a
stone, and consisted of some thirty individuals varying greatly in size. The smallest of
these are little knobs which hardly project 1 to 2 mm. above the ccenenchyma, the
largest are long cylindrical tubes, more than 1 cm. in length. They lie so thickly
compacted that the ccenenchyma is almost entirely covered, and only shows here and
there as a thin plate. The ccenenchyma is abundantly developed on the margin into
stolons, which are alternately broad and narrow.

I made a thorough anatomical examination of three individual polyps of different
sizes, which were highly contracted like all the animals of the colony. The upper end of
the wall is not only contracted but inverted a little ; the only indication of the point at
which we can reach the interior of the body is a small navel-like depression. Apart
from the folds caused by contraction, the surface of the body is perfectly smooth.

The wall (PI. XIV. fig. 4) is of considerable thickness, and consists histologically of a
homogeneous fundamental substance, with fine fibres embedded in it. The fibres are
hardly double contoured, are slightly waved, and run sometimes directly, sometimes
obliquely, from one epithelial surface to the other. They begin at the endoderm
with a granular enlargement which seems to pass directly into the epithelium ; towards
the ectoderm they branch repeatedly behind one another. They are furnished with
nuclei, and therefore bear a strong resemblance to the muscular fibres of the Ctenophora,
but their state of preservation did not admit of determining the histological value of the
fibres.

The cells of the connective substance are strongly granulated bodies, either rounded
or branched.

Finally, we find canals in the wall, such as do not exist in any other Actiniaria,
though they are found in the Alcyonaria. These canals vary greatly in diameter ; the
smaller are simple cords of cells, and only the larger ones show a lumen surrounded
by a layer of epithelium. As the canals repeatedly ramify and anastomose, they form a
thick net-work, which extends from the endoderm to the ectoderm, but is thickest near
the latter. Kolliker's observations show that in the Alcyonaria the canals are pro-
duced from the ectoderm, which is also the case in Zoanthus ; I have repeatedly found

REPORT ON THE ACTINIARTA. H3

that the epithelium of the hoily-surfa.ee sinks like a funnel into the mesoderm, where it
is prolonged into a broad or narrow canal which soon begins to throw out branches
(%. 2). '

The ectodermal epithelium is covered by a fibrous cuticle, which recalls the
" epidermis " of Phellia pectinata and Cereus spinosus. The endodermal epithelium has
produced a thin, circular muscular layer, and is traversed by small, roundish, sharply-
contoured bodies. I consider these bodies as parasitic, unicellular organisms of the
same kind as those which my brother and I have already observed in various species
of Actiniae. There was no visible trace of the usual yellowish and greenish colour,
but this was probably owing to the preservation in spirit.

In the inverted part of the wall I found a sphincter of a very peculiar nature (PI.
XIV. fig. 1). It consists of two perfectly separate portions, a larger, which begins at
the outer part of the wall, bends round at the inverted edge, and extends a little way
into the invaginated part, and a smaller, which lies at the boundary between the
wall and the oral disk. When the animal is expanded, this second portion of the sphincter
will lie above the larger portion of the muscle ; when the animal is contracted it occupies
the lowest part of the invaginated wall. A space without muscles, which does not
contract, and, therefore, becomes pleated, lies between the two portions.

Both parts of the sphincter are mesodermal and placed at an equal distance from the
endoderm and the ectoderm ; their bundles of fibrillse are arranged irregularly and
repeatedly crossed and interwoven in their course, so that the same transverse section
passes obliquely through some, transversely through others. The bulk of them lies in
the inverted part of the wall, whilst the muscles merely form a thin layer in the outer
part of the wall.

The oral disk bears a double corona of small tentacles, corresponding in number to
the septa, in that part of its periphery which is contiguous to the wall. The inner
tentacles communicate with the intraseptal spaces, the outer tentacles with the interseptal
spaces, the two are therefore placed alternately. The muscular system of the oral disk
and of the tentacles is ectodermal and extended in a smooth layer.

The distribution of the muscles can be very well recognised in the septa of the
strongly contracted polyps. The longitudinal muscular lamella is pleated both in the
small rudimentary septa and in the large septa so as to form a small muscular pennon,
whilst the fibrillse which rise obliquely are less strongly developed (PI. XIV. fig. 2). The
paired grouping of the septa is consequently very distinct, and we can also easily
distinguish the two pairs of directive septa from the ordinary pairs. The number of
the latter varies according to the size of the animal. In the largest polyp examined,
there were in all twenty-nine pairs of septa (PI. XIV. fig. 3). Of the two pairs of
opposite directive septa, one pair is rudimentary, does not bear mesenteric filaments, and
does not reach the oesophagus, whilst the other pair is perfect, bears mesenteric filaments,

(ZOOL. CHALL. EXP. — fART XV. — 1882.) P 15

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

and does reach the oesophagus. The remaining twenty-seven pairs are distributed in the
space to the right and left of the oesophagus, so that thirteen pairs lie on the one side
and fourteen pairs on the other. Each pair consists of a larger perfect macroseptum,
and a smaller imperfect microseptum.

If we term the side marked by the larger pair of directive septa, the ventral side, we
see that almost all the pairs of septa are placed in snch a wray that the larger, perfect
septa are directed ventrad, the smaller imperfect septa dorsad ; the two pairs of septa
next to the small dorsal pair of directive septa form the only exception to this rule as
their dorsal septa are the larger, their ventral septa the smaller. We can therefore
distinguish two systems of pairs of septa, a dorsal and a ventral. The result is the follow-
ing perfectly regular arrangement of the septa : as a rule the larger and smaller septa
alternate, but at three points two small septa lie between two large septa, viz., at the
dorsal end where the small pair of directive septa lie, and a little way further right and
left from the directive septa, where the dorsal and the ventral systems of septa are
mutually bounded by small septa.

At the ventral end, on the other hand, we find three spaces between large septa,
in which the small septa are wanting, viz., the intraseptal space of the large directive
septa, and the two adjacent interseptal spaces. To explain this more clearly I give
formulae for the dorsal (1), and for the ventral side (2), showing the distribution of
the septa.

1. Dorsal side, ( &c. gk gk : kg kg k \ k gk gk [ kg kg &c.

2. Ventral side, ( &c. kg kg kg kg g \ g gk gk gk gk &c.

In these formulae the letter g indicates the large septa, h the small septa, the dotted
lines the boundaries between the dorsal and ventral systems, the black lines the position
of the sagittal axis, the underlining the directive septa.

Three of the twenty-seven pairs of septa are still imperfectly developed, and much
smaller than the others ; the two pairs lying to the right and left of the ventral directive
septa, and the extra pair of septa which is only present on the one side. As I discovered
from other polyps of the same Zoanthus colony, the two pairs named at first are the
youngest in age. Their macrosepta resemble on the whole the small septa of the other
pairs ; they have no mesenteric filaments, and the uppermost section only reaches to the
oesophagus.

I got an explanation of the manner and sequence in which the septa are developed
from examination of a small polyp, only a few millimetres high. It had forty-eight
septa in all ; exclusive of the directive septa, there wTere twenty-one on one side and
twenty-three on the other (PI. XIV. fig. 6). In the region of the smaller directive septa,
the conditions were the same as in the developed polyps, but towards the ventral side the

.REPORT ON THE ACTIXIARIA. 115

septa all became smaller as they approached the larger directive septa ; on one side only
the first seven, on the other side only the first six, macrosepta reached the oesophagus, tin n
followed five other macrosepta which still decreased in size, so that the smallest, which
came next the ventral directive septa, hardly projected at all into the gastric space. The
microsepta left off still earlier, for they became smaller in exact proportion to the macro-
septa, and as they were in general less they disappeared sooner. On the ventral side the
directive septa only were perfect, and were separated by a wide interspace from the septa
which were next in development.

Two facts may be deduced from the above observations : (1) The macrosepta and
microsepta can be distinguished from the first by the difference in size ; they develop
independently and at different periods, whilst in the Hexactinise and Paractinise the septa
of a pair start simultaneously and are of the same size from the first. (2) The septa are
not produced regularly in the periphery of the body of the Actinia, but within a limited,
ventral productive zone. The dorsal septa are therefore the oldest, the ventral septa the
youngest, with the exception of the directive septa, which are developed very early.

The third polyp was intermediate between the two specimens described, both in
the size and the number of its septa, which amounted to fifty-two. A more minute
description of it is therefore unnecessary, and I shall conclude my remarks on the
Zoanthese with some details as to the structure of the septa.

A cellular cord, or a canal filled with cells, rims in the supporting lamella of the septa
in immediate proximity to the wall (PI. XIV. fig. 2). It is usually divided into several
cords by commissures of the supporting lamella and is of such strength that the whole
septum becomes visibly and locally thickened. I never could make out any connection
between this septal canal and the ectodermal cords of the wall in any of the numerous sec-
tions which I prepared, and I am inclined to believe that it is produced from the endoderm.
My reason is that I have observed that the same roundish bodies which are to be found
in the endoderm, which I regard as parasitic, unicellular organisms, force their wray into
the septal canal, but never into the canals of the wall. I attach less importance to the
origin of the canals, as they seem to be connected with the endoderm here and there where
the septa spring from the wall. However, the figures, which led me to consider such a
mode of connection as probable, did not furnish sufficient proof of its actual existence.

The structure of the mesenteric filaments is essentially the same as in the Actiniae ; dur-
ing the greater part of their course they consist entirely of the median glandular streak,
and it is only a little way below the oesophagus that they are widened by the addition of
paired ciliated streaks, the surface of which is indented at regular intervals by transverse
furrows. This upper section of the mesenteric filaments appears to me identical with the
"flattened organs" described by Yerrill as "having a curved or crescent form and a
transversely striated surface, — attached to the principal radiating lamellae, near the base
of the stomach" (Trans. Connect. Acad., vol. i. p. 491). Yerrill, Andres, and others

11(> THE VOYAGE OF H.M.S. CHALLENGER.

erroneously consider these organs as peculiar to the Zoanthese, and explain them to he
gills, a view which is, however, quite unwarranted.

I did not find reproductive organs either in the three polyps minutely examined or
in several others which I only opened longitudinally.

The coenenchyma consists of the same tissue as the wall of the polyps, but the pro-
portions of the component parts are altered. The branched fibres are more scanty and
crossed irregularly in every direction, whilst the cells of connective substance are re-
markably abundant, and many of them have assimilated black granules, and so become
branched pigment cells. The ectodermal canals are more numerous than usual, and
form a thick net- work ; it is often difficult to distinguish them from the endodermal con-
nective tubes, which run from one polyp to another, and which also may become branched
into small vessels.

Epizoanthus, Gray.

Zoanthidse, in which the outer layer of the body is encrusted with sand granules ;
coenenchyma a thin lamella usually stretched over Gasteropod shells which have been
abandoned by their owners and are inhabited by Paguri ; polyps projecting considerably
above the surface of the coenenchyma.

Epizoanthus parasiticus (PI. III. figs. 2, 9, 12 ; PL XIV. fig. 5).

Zoanthus parasiticus, Verrill, Memoirs Boston Soc, vol. i. p. 34.

The upper part of the wall of the polyps, which is a few millimetres broad, separated
from the lower by a circular furrow, forming a shallow disk when contracted, and covered
with forty radial ridges; tentacles seventy to eighty, filament-shaped, arranged in two rows.
Colony parasitic upon a Gasteropod shell, the calcareous components of which have been
absorbed and replaced by the coenenchyma.

Habitat.— Station 235. June 4, 1875. Lat, 34° 7' N., long. 138° 0' E. Depth,
565 fathoms. Two specimens.

Dimensions. — Height of the individual polyps, l-5-2-5 cm. ; breadth, 1 •4-1*7 cm.

Epizoanthus parasiticus, of which there were two specimens among the Challenger
material, belongs to those Actiniaria which settle as parasites on shells inhabited by
hermit crabs. As Verrill, who was the first to give a detailed account of Epizoanthus,
observed, the Gasteropod shell is almost entirely dissolved, even the columella being com-
pletely replaced by the coenenchyma of the parasite. The form of the shell, however,
is still retained, and the hermit crab continues to live comfortably inside, undisturbed
by the changes which his home has undergone. The snail shell can only be recognised
externally by the wide opening and the point which projects as a stumpy knob.

REPORT ON THE AGTIXIARIA. 117

The number of the individual polyps and their arrangement on the surface of the body
is almost the same in both the colonics investigated. Eight polyps are uniformly distributed
along that circumference which divides the upper half of the shell from the lower when
the I'liij/trus is crawling about on the bottom ; the polyps just mentioned are the largest
and most powerful of the colony, and are plainly most favourably placed for acquiring
nutriment, as they are always at a little distance from the bottom (PI. III. fig. 2). A
medium-sized polyp rises nearly in the middle of the convex upper side of the colony, and
in one colony a second smaller polyp lay close beside it. On the lower side an obviously
rudimentary polyp grows on the posterior margin of the opening of the shell (fig. 9);
it has the best position on the lower side, which is on the whole disadvantageous to
development, as ii is raised from the bottom as Long as the Pagurus is crawling about,
and only lies upon it when the Pagurus has retreated into the shell. In the colony
consisting of eleven individuals there was the indication of a twelfth between the eight
marginal polyps. It may be taken as a general rule that the distribution of the polyps
on the surface of the colony is not accidental, but that those spots are preferred in which
the animal has room for free development, and also a convenient position for acquiring
nutriment.

The whole surface of the colony is covered by a dirty yellow substance permeated
by sand granules, which can be easily scraped off; underneath this the fundamental
substance of the wall becomes visible, which resembles cartilage in consistency and
colour, and is also hardened superficially by sand granules. This hardened layer is so
thin that it can be removed by sections parallel to the surface, and yet leave sufficient
fundamental substance both in the ccenenchyma and the wall for transverse sections.
These conditions were extremely favourable to examination, so that I regretted the more
that the colonies were not better preserved.

The large marginal polyps were 2-2-5 cm. high, 1*4-1 '7 cm. broad, and slightly
flattened from above downwards. The upper part of the wall is inverted, and forms a
horizontal roof ; this might be taken at first sight for the oral disk, as it is separated from
the bulk of the wall by a circular furrow, and also differs in its structure, being furnished
with numerous (about forty) radial ridges, already observed by Verrill, which are broad
where they begin at the margin and become narrower as they run inwards. The radially
striated part of the wall is distinguished from the oral disk by being encrusted with sand
granules like the rest of the wall. In the middle of this horizontal roof is a fissure
running parallel to the margin of the colony, through which, in many polyps, the points
of the incompletely retracted tentacles peep out. Through this fissure we may reach the
inside of the polyp, first passing through the space lying above the oral disk.

The fundamental substance of the wall is homogeneous, but in transverse and
longitudinal sections it shows a striation parallel to the surface of the body, which looks as
if it were deposited in layers (PI. XIV. fig. 5). The striated layers are crossed by fine

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

fibres, which end in repeated branches tinder the ectoderm like those of Zoanthus, but
are more numerous, more sharply contoured and waved repeatedly in their course.
Besides the branched corpuscles of connective tissue, small and large islands of cells lie
in the supporting substance; I presume that these islands of cells represent the system
of cellular cords which are always found in Zoanthus, but are wanting in Epizoanthus.
At certain points they are prolonged into longish sausage-shaped cords, several of which
may also become united into a dendritic figure. In many parts of the ccenenchyma
I still found the remains of a branched vascular system, which formed very small
meshes, especially about the endodermal connective tubes. I therefore feel justified
in my conjecture that the oval islands of cells are caused by the unsatisfactory state
of preservation, and are produced by the disintegration of a system of anastomosing
cords.

A powerful circular muscle lies in the horizontally inverted part of the wall ; it is
broad at the beoinninw of the oral disk and becomes narrower from within outwards.
The imperfect state of preservation did not allow me to give any histological descrip-
tion of its bundles of fibrillar which run in the mesoderm between the ectoderm and
endoderm. I could not make out that it was divided into a larger and a smaller part as
in Zoanthus.

The large size of the individual polyps of Epizoanthus parasiticus renders them
admirably suited for cbssection by means of knife and scissors. If we cut open the animal
longitudinally and spread it out by turning back the upper end of the wTall (PL III. fig.
12), wre find adjacent to the latter, the double corona of long, filamentous tentacles,
the aggregate number of which amounts to seventy or eighty. The tentacles of the inner
row alternate with those of the outer. The oral disk extends far down, and is covered
with shallow radial furrows corresponding to the tentacles. It is divided by a distinct
thickening from the oesophagus, in which our attention is at once attracted to the single
oesophageal groove. When spread out the oesophageal groove forms a scutiform plate,
separated from the adjacent parts of the oesophagus by longitudinal furrows, and divided
by a more distinct median furrow into a right and a left half; it is prolonged far below
the lower margin of the oesophagus, so that it is almost twice its length. The triangular
lappet formed in this way is likewise divided into twTo by the prolonged longitudinal
furrow, and deeply indented at the end.

Below the lower margin of the oesophagus there are seen thirty-two to thirty-four septa,
the zigzag margins of which are caused by the reproductive organs ; these are macrosepta,
the microsepta only becoming visible when the others are folded back. I examined the
mutual relations of the two kinds of septa in transverse sections and with essentially the
same result as G. v. Koch in Epizoanthus axinellce (Morphol. Jahrb., Bd. vi. p. 359, 1880).
Two pairs of directive septa lie at the ends of the sagittal axis, the dorsal pair consisting
of microsepta, the ventral of macrosepta ; the latter only reach the oesophagus and are

REPORT ON THE ACTINIARIA. 119

attached close to the oesophageal groove, which is also ventral. Besides these there are
fifteen pairs of septa on either side (if the aggregate number of pairs of septa is increased
to thirty-three, there are sixteen on one side and fifteen on the other), which consist of
(1), a pair of septa adjoining the dorsal directive pair, and having the dorsal septum
larger than the ventral ; (2), thirteen pairs of septa situated towards the ventral aspect of
the body, and having the ventral septum larger than the dorsal ; and (3), a pair consisting
of two macroscpta and lying between the two above mentioned groups. The distinction
then between Epizoanth us parasiticus and Epizoanthus axinellcB on the one hand and
the true Zoo. nth us on the other, is that in the latter the two systems are separated by
microsepta, in the former by macrosepta, so that a pair of septa is madeup of one septum
from either system.

The remarks made by me on the septal canals and mesenteric filaments of Zoanthus
apply equally to Epizoanthus parasiticus. The reproductive organs were well developed,
and seemed to lie only on the macrosepta, and that without exception ; they were testes in
the specimen which I examined in transverse section.

The individual animals of the Epizoanthus colony were united at the base by a
tolerably thick crust, in which numerous canals run from one polyp to another ; all the
canals extend with repeated anastomosis in one and the same layer of the ccenenchyma.
Hence if we cut a colony through longitudinally, the ccenenchyma is separated by the
vascular stratum into a broader external and a narrower internal layer ; the character of
the tissue is the same in both, except that the inner layer is without branched fibres.
The gastric spaces of all the polyps reach as far as the vascular stratum, in which
lies a very large canal surrounding the opening of the shell like a ring (PI. III. fig. 9).

The hollow of the shell enclosed by the ccenenchyma is lined by a chitinous
membrane, which lies firmly attached to the thin layer of the ccenenchyma, and has a
structure of its own. Two lamellae are separated from one another by an interspace,
and are connected by perpendicular septa parallel to one another which divide the inter-
space into numerous tubes and smaller prismatic spaces. I leave it an open question
whether this chitinous membrane is the last remains of the Gasteropod shell or a cuticular
formation secreted by the superficial epithelium of the Epizoanthus.

The mode of life of Ep'r.oanllnis parasiticus is the same as that of Epizoanthus
papillosus and Epizoanthus cancrisocius, the former of which was described by Gray in the
Proceedings of the Zoological Society, 1867, p. 237, the latter by Studer in the Monats-
berichten der Berliner Academie, Jahrg., 1878, p. 547. Both forms settle on Gasteropod
shells, occupied by a hermit crab, and completely absorb the calcareous parts of the shell.
The upper section of the wall oi Epizoanthus papillosus appears to be of the same nature
as that of Epizoanthus parasiticus. I draw this inference from Gray's words in the
description given of the individual polyps, " The apex when expanded is fiat, with close,
radiating white lines." It is therefore still a question whether these arc merely allied

L20 THE VOYAGE OF H.M.S. CHALLENGER.

species or whether Epizoanthus papillosus and Epizoanthus cancrisocius are identical with
Epizoanthus parasiticus.

Family Sphenopid^;.
Solitary Zoantheas with the posterior end of the body rounded.

Sphenopus, Steenstrup.

Sphenopidse with thick wall, the uppermost layers of which are encrusted with sand
granules ; with strong mesodermal sphincter.

Gray, in his system of the Zoanthese (Proc. Zool. Soc, 1867, p. 236), has erected
several genera, in which the individual polyps remain solitary, and are either firmly
attached to the bottom or stick in the sand by means of the rounded body-end, viz.,
the genera Isaurus, Pales, Ovinia, and Sphenopus. As no thorough anatomical studies
have been made as yet of all these forms, it is doubtful in the meantime whether they
ought to be placed among the Zoanthese or not. Sphenopus is the only one of which I can
affirm that it belongs to the Zoantheae, as the macrosepta and microsepta are visible in
regular order, and the oesophagus has only one oesophageal groove.

Sjyhenopus arenaceus, n. sp. (PL II. fig. 10, PL XIV. fig. 8).

The greater part of the wall is encrusted with sand granules, and so transformed iuto
a kind of carapace ; tentacles small and pointed, about sixty in number, distributed in two
rows ; thirty macrosepta and the same number of microsepta.

Habitat. — Cape York. (? The title of the label enclosed with the preparation was
nearly entirely destroyed by the rough surface of the animal, and could not be exactly
made out.) One specimen.

Dimensions. — Length, 4-5 cm. ; breadth, 2*8 cm.

Colour. — -(Determined from the spirit specimen) brown-red.

The wall of Sphenop>us arenaceus, a new species, which I erect here from a single
specimen among the Challenger material, is encrusted with foreign bodies to a degree which
I have never found in any other Zoanthea ; it forms a firm unyielding capsule, in which
the soft parts are completely concealed when the animal is strongly contracted. The form
of the Sphenopus then becomes irregularly oval, rather smaller at the rounded posterior
end of the body than at the anterior. The wall is inverted a little way at the anterior
end, though its nature does not undergo any change.

The surface is regularly rough like shagreen, as the sand granules are nearly all of equal
size. The granules force their way so deeply into the wall that only a thin layer of
soft tissue remains on the endodermal side ; it is broadest in the front, and becomes nar-
rower as it runs backwards, till the wall at the aboral body-pole consists almost entirely of

REPORT ON THE ACTINIARIA. 121

a layer of sand 5 millimetres thick (even in PL II. fig. 10 the soft part of the wall is too
large in proportion to the layer of sand granules). Where the sand grains are absent the
fundamental substance is homogeneous and furnished with two different forms of cells,
small branched cells and larger roundish ones, the latter being entirely filled with strongly
refractive concrement-like granules. The tissue between the sand granules (PL XIV. fig. 8),
on the other hand, appears rather fibrous, and even the corpuscles of connective tissue are
fusiform in shape. The direction of the fibres and the fusiform cells is parallel to the
surface of the body. In most parts the sand granules are so thickly compacted that the
fundamental substance is entirely covered.

There are no ectodermal vessels in the wall, but the supporting fibres are very
numerous ; they are richly furnished with granular protoplasm, are very fine and
branched on the endodermal side, whilst towards the ectoderm they become lost among
the sand granules.

The mesodermal circular muscle, which is strongly developed as in the other Zoanthese,
is not confined merely to the inverted part of the wall, but extends a good way down
into the outer section. It is strongest where it begins close to the oral disk and lies
in the non- encrusted section of the wall, it then becomes narrower and gradually
approaches the endoderm, till the lower end almost touches the epithelium. It consists
of bundles of fibrillse, which give repeatedly waved figures in transverse section ; several
bundles are united into roundish bundles of the second order, which remain farther apart
from one another.

Whilst the wall is very thick and firm, all the inner parts consist of delicate, easily
torn lamellae. The oral disk only is tolerably strong, and foreign bodies (sponge spicules,
sand granules) are enclosed here and there in its supporting lamella. It is covered by a
smooth layer of ectodermal radial muscles, and the margin bears two rows of tentacles ;
I could not determine the number of the tentacles accurately because of the strong con-
traction, but there were probably about sixty of them.

Before the oral disk passes into the oesophagus, which is of considerable size, it rises
into a thin, sharp-margined lip, which is repeatedly indented at the edge. A large
number of longitudinal ridges of the oesophagus, which correspond to the origins of the
perfect septa, spring from these indentations.

The oesophageal groove is remarkably distinct ; it is distinguished by its depth, and is
enclosed by two broad folds, almost as hard as cartilage. Gray probably had these folds
in mind when he specially mentions that in Sphenopus marsujiinUs " the laniinas of
the stomach have a cartilaginous edge." They extend a little way beyond the lower
margin of the stomach and form a projection, resembling the prow of a boat.

The arrangement of the septa agrees essentially with that already described in detail
for Zoanthus, sp. ? Two small directive septa lie at the dorsal end of the oesophagus,
two large directive septa at the ventral end, which is easily recognised by the oesophageal

(ZOOL. CHALL. EXP. PART XV. 1882.) P 16

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

groove; two pairs, with dorsal macroaepta and ventral microsepta, adjoin the former on
either side ; twelve pairs, with ventral macrosepta and dorsal microsepta, adjoin the latter.
The small dorsal and the large ventral septal regions are therefore separated on either
side by microsepta. There are in all thirty macrosepta and thirty microsepta.

The following observations seem to me to justify these statements. From the
dissection of individual septa, it was evident to me that the oesophagus is surrounded by
two kinds of septa, viz., macrosepta, which are attached along the entire length of the
oesophagus ; and microsepta, which end on the oral disk before it becomes raised into the
oral lip. In all of them the muscular fibres which rise oblkpiely are very distinct, the
longitudinal fibres less so.

The only example of Sphenopus arenaceus which I was able to examine was bisected
longitudinally parallel to the sagittal plane, so that only the one half (PL II. fig. 10)
contained the oesophageal groove and the septa fastened to it. At the end of the
oesophageal groove three macrosepta followed one another before I liberated the first
microseptum by dissection, whilst the adjoining part of the other half begins with a
microseptum, and the macrosepta and microsepta come alternately. If we then
compare the transverse section through Zoanthus (PI. XIV. fig. 3), we find a similar
arragement of the septa in the region of the oesophageal groove, except that in Sphenopus
the outermost of the four macrosepta placed in a row in Zoanthus is wanting. As it falls
in the line through which the section has been taken in dividing the animal, it has most
likely been destroyed.

At the dorsal end we first meet with a microseptum, then with a macroseptum ; after
which, on dissection, I found the septa arranged in the following order, two microsepta, one
macroseptum, one microseptum, one macroseptum, one microseptum, one macroseptum. In
the adjoining portion of the other half, I found one microseptum, one macroseptum, One
microseptum, one macroseptum, two microsepta, one macroseptum. If we compare this
arrangement with fig. 3 of Zoanthus, and consider the two pairs of microsepta discovered
by dissection to be homologous with the two lateral pairs of rnicrosepta in Zoanthus, we
should likewise meet with the same corresponding conditions if we assume that one of
the small directive septa and the adjoining macroseptum have been destroyed in making
the section.

Finally, as regards the number of the septa, I determined them according to the lines
of insertion which shone through the oesophagus ; in this way we can settle the number of
the macrosepta, with which the number of microsepta corresponds, presupposing, of course,
that they are arranged in the same way as in Zoanthus. I found this to be the case
in at least half of the septa dissected.

The reproductive organs and mesenteric filaments were cemented by mucus into a
badly preserved mass, and were not adapted for examination.

IM'.I'OKT ON Till: ACTINI AIM \. 123

Tribe VI. Ckuianthe^;.

Actiniaria with numerous unpaired septa and a single ventral oesophageal groove;
the septa are longest on the ventral side and gradually diminish towards the dorsal
aspect; the two septa attached to the bottom of the oesophageal groove (directive septa)
are remarkably small, and are distinguished in this way from the other ventral septa.

I have made no further anatomical investigations of the Cerianthese, and cannot
even complete the statements which were formerly made by von Heider (Sitzungber. d.
Wiener Akad. Math. Naturw. CL, Bd. lxxix. Abth. 1, p. 204, Jahrg., 1879), and my
brother and myself (Aetinien, p. 107). From these we cannot even certainly determine
what position the animals occupy in the circle of the Actiniaria, and whether or not they
ought to be placed in one of the known principal divisions. They are distinguished from
all the forms previously discussed, except the Edwardsise, by the fact that they want the
paired arrangement of the septa — at least up to the present it has not been observed in
them. They come nearest the Zoantheae, as they have only one oesophageal groove ; the
septa also appear not to be disposed in a circle, but in the region of a limited zone of
growth, which, however, lies dorsally, not ventrally as in the Zoanthese. In this case the
largest septa are found in the region of the oesophageal groove, and the septa gradually
decrease in size from that point to the opposite end of the sagittal axis; two pairs of very
small septa lie under the oesophageal groove, to which the name of directive septa is given
more from their position than from their anatomical constitution.

Family Cerianthid.e.

Ceriantheae with a double corona of tentacles, marginal principal tentacles and circum-
oral accessory tentacles, posterior end of the body rounded, without sphincter.

Cerhirrfhus, Delle Chiaje.

Cerianthidse with aboral pore, with a sheath consisting of mud, sand granules, and
nematocysts, in which the posterior end of the animal lies as if in a case.

Cerianthus americamis.

Cerianfh it* ttnirririiiiii.-t, Vcrrill, Memoirs Boston Soc, vol. i. p. 32, I860.

Habitat— Station 321. February 25, 1876. Lat, 35° 2' S., long. 55° 15' \Y.
Depth, 13 fathoms. One specimen.

Dimensions. — Length of the animal (in the contracted condition), 12 cm.; breadth of
the oral disk, 3"5 cm.; length of the inner tentacles, 2-2"5 cm. ; of the outer tentacles,
4-5 cm.

12-4 THE VOYAGE OF H.M.S. CHALLENGER.

Most species of the genus Cerianthus are far surpassed in size by Cerianthus aineri-
canits, which Verrill only has hitherto described. His account of it is as follows :
" Column very long, cylindrical, expanded at the top, tapering gradually below ; in
expansion, often two feet or more long, in contraction, six or eight inches. Body enclosed
in a loosely investing tube, buried in the mud. Tentacles long and numerous, the outer
series (125 or more) are from l-25 to 1"50 inches long, slender, very flexile, usually
much curled at the ends; inner series similar, about '75 long, nearly the same as the
former in appearance ; often brought together and spirally twisted in a central bundle.
Base with a small but distinct opening.

" Color of column dark cinnamon-brown, lined longitudinally with a lighter tint of
the same ; outer tentacles cinnamon-brown, lighter at the bases ; inner series darker,
marked with white longitudinal lines ; disk bright yellow, the central portion brown ; at
the bases of the tentacles spotted with dark brown."

I consider the single specimen of the genus Cerianthus dredged by the Challenger as
identical with Cerianthus americanus. As it is more than 12 cm. long, it may easily
have measured more than 50 cm. when alive. The number of the outer tentacles, which
I reckoned at about two hundred, is larger than in the specimens examined by Verrill,
whilst their length is about the same. The distribution of colour on the tentacles was no
longer recognisable, as the whole colour of the animal had been changed by the spirit. I
did not attempt an anatomical examination, as I did not wish to destroy the unique
specimen.

REPORT ON THE ACTINIA RTA. 125

APPENDIX.

By way of appendix I shall describe some forms whose systematic position I was
unable to determine, as their state of preservation did not admit of an anatomical
investigation of the inner parts, especially of the septa.

Two of them seemed to me to be closely related and to belong to the same genus
Porponia., and I shall discuss them in detail as interesting species, though I have not
done so in the case of the others.

Porponia, n. gen.

Actiniaria (Hexactinise ?) with two oesophageal grooves, without circular muscle,
with thin-walled tentacles, the bases of which are supported on the outer side by clasp-
like prolongations of the wall.

Porponia elongata, n. sp. (PI. I. figs. 1, 2).

Body elongated, sessile, wall cartilage-bike, small, upper end terminated by twenty-
seven knobs forming supporting clasps for the outer sides of the same number of long)
thin-walled tentacles ; twenty-seven additional tentacles placed in an inner second row,
and alternating with the outer tentacles.

Habitat.— Station 1G0. March 13, 1874. Lat, 42° 42' S., long. 134° 10' E.
Depth, 2600 fathoms. Two specimens.

Dimensions. — Height, 5-5 cm.; breadth of the base, 2"5-3-5 cm.; breadth of the oral
disk, 3-0-4-0 cm. ; length of the tentacles, l"5-2"5 cm.

Whilst the majority of Actinias, especially those from great depths, form a short
column, and are frequently flattened into a disk, the body form of Porponia elongata, a
new species taken from a depth of 2600 fathoms, approximates that of the elongated
Cerianthidas. In both specimens examined the body, though contracted, was twice as long
as high. It is broadest in the region of the oral disk, below which it becomes a little
narrower, and then becomes broader again at the pedal disk, by which it is firmly attached
to the bottom. It was impossible to recognise the original colour of the animal, but this
was partly owing to the fact that the ectoderm was completely macerated away.

The pedal disk is thin and the insertions of the septa shine through it as whitish,
radial lines. There are altogether about thirty-two to thirty-four such lines, some of
which, however, only project a little way towards the centre of the pedal disk. Setting

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

these asides we can count in both cases twenty-eight almost equally distinct lines, which
appear to he grouped in pairs.

Contrasted with the pedal disk the wall is very thick, as it measures 2-3 mm. in
transverse section, and by reason of its cartilaginous hardness forms at the same time a
most powerful protection for the parts covered by it. The surface is smooth and only
traversed here and there by furrows, which may, however, be absent in the living
animal; the upper margin ends in pointed knobs which project like battlements above
the enclosed oral disk. The number of the knobs appears to be constant, as it amounted
to twenty-seven in both the larger and the smaller specimen examined, though they
differed in size. The larger and smaller knobs are placed irregularly, so that sometimes
both kinds alternate, sometimes several knobs of the same size lie beside one another.

The oral disk, which springs from the wall at the base of the knobs, is as thin as
tissue paper and correspondingly transparent. Numerous (probably fifty-four) white
radial streaks denote the insertions of the underlying septa.

The tentacles, like the oral disk, are very thin-walled and delicate, and are l"5-2"5
cm. long. The base is of medium breadth ; they then diminish rapidly in size, and run out
into a long fine point, through which even pressure cannot expel the contents of the
tentacles, thus showing the absence of the terminal opening common to many Actiniaa.
They are placed in two alternating rows of twenty-seven tentacles each. The outer
tentacles spring immediately on the inside of the twenty-seven knobs of the wall, which
may therefore be regarded as clasp-like thickenings of their basal sections ; the inner
tentacles alternate with the outer, and are placed so close to them that their bases are
partially inserted into the interspaces between the outer tentacles.

The oral disk is covered by a thin ectodermal slightly pleated layer of radial mus-
cular fibres, which extend as longitudinal fibres into the tentacles ; in many places it had
fallen away along with the epithelium lying above it. There were still fewer of the
circular endodermal muscular fibres preserved.

The oral angle and the oesophageal grooves are very distinct in the oral fissure and
the oesophagus. The oesophageal grooves are only a little longer than the rest of the
oesophagus, but on the other hand they are of considerable breadth, and occupy about two-
fifths of the whole extent of the oesophagus. The side walls of the grooves are repeatedly
folded in a transverse direction. Longitudinal folds, nine in the one case, eleven in the
other, which begin with the same number of knobs at the margin of the oral fissure, run
on the two intermediate portions of the oesophageal wall. The oral margin itself projects
as a ridge, just as the oral disk in Sphenopus arenaceus is very much raised before it
passes at an acute angle into the oesophagus.

There are, altogether, twenty-eight septa inserted into the oesophagus — veil-like,
extremely delicate, easily torn membranes, never pierced by septal stomata. It was
impossible to arrive at any decided opinion as to their structure and arrangement, both

REPORT ON THE ACTINIARIA. 127

specimens having been badly preserved. As both the ectodermal epithelium and muscles

were almost entirely macerated away, so also all the endodermal parts formed a disinte-
grated mass in the radial chambers. The muscles of the septa were nowhere preserved, so
that I could only form an idea (if their course from the furrows on the surface of the
supporting lamellae. These were, however, not very distinct, as the muscles of the septa,
like the muscles of all the other organs, are extremely weakly developed ; as far as I
could make out each septum bears longitudinal muscles on the one side, and transverse
muscles on the other, as in other Actinias.

All the septa are furnished in the section below the oesophagus with reproductive
organs which reach like long, broad, folded bands almost as far as the pedal disk, but tli.
mesenteric filaments were macerated away and nowhere to be found.

Besides the twenty-eight perfect septa there are imperfect septa, which only reach as
far as the middle of the oral disk, and do not bear reproductive organs. I did not
determine the number of them by direct observation, as in order to do this I should have
been obliged to dissect the entire animal, and I could not make up my mind to this,
considering how insufficiently it was preserved. I estimate them at twenty-six, as in the
majority of Actiniaria the aggregate number of the tentacles nearly corresponds to that
of the septa.

Though the anatomical description here given is but deficient, I consider myself justi-
fied in regarding Porjjonia elongata as a form systematically interesting. The position
of the tentacles in a double row, the presence of perfect reproductive septa (macrosepta)
and imperfect sterile septa (microsepta) are characteristics which recall the Zoantheas ; the
numbers of the tentacles and the septa likewise agree with those of this group, as they are
neither multiples of the number six, as in the Hexactinise, nor of the number four, as in
the Paractinise. On the other hand, having two oesophageal grooves, Porponia elongata
comes closer to the Hexactinise, among which, as I have already specially observed (p. 30),
it most resembles the Antheomorphidaa. I therefore consider it most likely that Porponia
elongata is an intermediate form between the Hexactinise and the Zoanthese.

Porponia robusta (PI. I. fig. 10).

Body compressed, as high as broad, sessde ; wall tough, the upper end prolonged into
numerous scimitar-shaped processes, which support the outer walls of the long, thin-
walled saccular tentacles.

Habitat.— Station 237. June 17, 1875. Lat. 34° 37' N., long. 140° 32' E. Depth,
1875 fathoms. One specimen.

Dimensions. — Height, 4 cm. ; breadth of the oral disk, 4 cm. ; breadth of the pedal
disk, 3 cm.

The single specimen of Porponia robusta had unfortunately been preserved in
chromic acid, and had therefore become so brittle that I must confine myself to a
description of the external form of the body. The animal is shaped like a short,

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

compressed cylinder; it becomes a little broader towards the pedal disk, but very
markedly so in the upper half, so that the margin of the oral disk is turned outwards
even when the animal is fully contracted.

The pedal disk and oral disk are thin-walled, but the wall itself is of considerable
thickness ; its upper surface is smooth, for though there are oblique and longitudinal
wrinkles and furrows they are plainly owing to contraction. There is no circular muscle,
as may be gathered from the form of the anterior end of the body. A single row of ten-
tacles stands on the margin between the oral disk and wall ; they look like long, wide, thin,
membraned sacs, and do not become smaller at the ends. A firm clasp, quite 1 cm. loner,
runs on the outer wall of the tentacles, as a prolongation of the body-wall ; it is broadest
and thickest at the base, and gradually becomes narrower and thinner towards the end.
As the tentacles, in consequence of contraction, are turned over towards the oral disk, the
tentacle clasps are also bent inwards like a scimitar, many of them so much so that they
lie obliquely above the oral disk. I was unable to determine the exact number of the
tentacles, as they were bent confusedly over one another, and the friable nature of their
clasps prevented me from trying to separate them. They amounted, however, to more
than forty.

Besides the longitudinal ridges, I found two oesophageal grooves on the oesophagus,
one of them much more strongly developed than the other. After I had removed the
pedal disk by a horizontal section, I was able to count the septa, of which there were
thirty-eight, separated from one another by interspaces of equal size. They appeared to
me all to bear reproductive organs, but only to extend partially to the oesophagus. They
also projected more or less towards the centre of the pedal disk.

In this appendix I have still three forms of Actiniae to consider besides the Porponice.
The first was taken at Tristan da Cunha, at a depth of 1000 fathoms, and appears to be a
Phellia. The body, 1*3 cm. long and 1"0 cm. broad, is covered with a finely granulated,
brownish, leather-like cuticle, which is wanting on the short inverted part of the wall.
A strong circular muscle, which contracts the wall to such an extent that the entrance to
the oral disk is completely closed, lies in the inverted portion of the wall. I can say
nothing as to the number of the very small tentacles, and I was also unable to examine
the number and nature of the septa more minutely.

The two other forms of Actinias were taken along with the four specimens of Cereus
spinosus and the single specimen of Poiponia robusta, at a depth of 1875 fathoms, on
June 17, 1875, at station 237 (lat. 34° 37' N.; long. 140° 32' E.) ; like the Actinia
just mentioned, they had been placed in chromic acid, and were therefore but little
adapted for examination.

In the one instance I had to do with an Actinia, which so strongly resembled the
Dysactis crassicornis described on page 44, that I was long inclined to consider it as
the same species. As in Dysactis crassicornis, the muscles on the oral disk and

REPORT ON THE ACTINIARIA. 129

tentacles are mesodermal; the strong sphincter, which is also enclosed in the mesoderm,
lies close under the endoderm, and contracts the wall so strongly that the surface becomes
arranged in ridge-like, projecting folds. The tentacles only are different ; they are placed
in four alternating rows, are equal to one another in size, and are much longer and more
powerful than in Dysactis crassicornis, so that even when contracted they form slightly
curved horns 3 cm. long. The most striking point, however, is tin wide, gaping opening
at the free end, from which one might give the animal the specific name tubulifera.
This Actinia probably belongs to the genus Paractis, the smooth surface of the wall, the
mesodermal circular muscle, and the equality of size in the tentacles of the individual
rows being common to both. The two specimens of this Actinia before me air both
3 cm. high and G cm. broad at the pedal disk ; they become smaller towards the upper
cud, the diameter of wdiich only amounts to 2"5 cm.

The last Actinia to be considered belongs to the forms in which the tentacles have
undergone retrograde formation, on account of which I have named it Liponema
multvporutn,. The only specimen of it was hardened in chromic acid and also greatly
injured, a combination most unfavourable for examination. The pedal disk and the lower
part of the wall were torn, the oesophagus forcibly protruded and also torn, so that the
oral disk was stretched and misplaced ; it formed the side walls of the body, and this led
me at first to take it for the wall and the wall for the pedal disk, till I discovered my
mistake in examining it histologically.

The oral disk is devoid of freely moving tentacles, but lias instead numerous,
small stomidia, roundish openings not measuring more than 2 mm. in diameter. The
tentacles in Liponema multiporum have undergone retrograde formation to a greater
extent than in any other Actinia, as there are not the smallest remains of then' walls,
while in Pobjopis these can still be recognised as thickened ridges surrounding the
openings (PI. XIV. fig. 7).

Part of the stomidia, which number several hundreds, are arranged on the margin of
the oral disk in a repeatedly waved circle, the remainder lie at short distances from one
another on the oral disk, on which they are distributed nearly to the oral opening. After
dissecting a number of septa I became convinced that more than one stomidium
communicates with each radial chamber ; in fact, I believe that the marginal openings
must be considered principal stomidia, the others accessory stomidia. We therefore
have here the same conditions as in the Discosomidaa and Corallimorphidae, if we
consider the tentacles to be replaced by the stomidia. The oral disk is covered with
numerous fine ridges which wind between the accessory stomidia and so have a very
sinuous course. The radial muscles are ectodermal and borne by fine supporting folds,
having the same constitution as in Cerianthus. I have also examined the circular muscular
system of the wall ; I found it thickly pleated in the whole upper region of the wall,
especially in the part adjoining the oral disk, where it formed a kind of sphincter. The
pleating ceases rather suddenly at the outer margin of the principal stomidia. The

(ZUOL. CUALL. E.\r. — l'AKT xv.— 1882.) p 17

ISO

THE VOYAGE OF H.M.S. CHALLENGER.

muscular folds of the layer of circular muscles arc very long, and thickly branched only
at the base, so that a principal fold soon becomes divided into numerous parallel
secondary folds.

Survey of the Actinia examined.

If New

Number

Family.

Genus.

Species.

Depth in
Fathoms.

Station.

Habitat.

of
Speci-

Species.

Genus.

mens.

Corallimorphidae

Gorallirnorphus

profundus

2025

293

39° S. 105° W.

n. sp.

n. g.

1

n

n

n

1375

300

33° S. 78" "W.

n. sp.

n. g.

1

11

>)

rigidus

1375

146

46° S. 45° E.

n. sp.

n. g.

3

11

>>

n

1950

157

53° S. 108° E.

n. sp.

n. g.

1

))

»

n

1425

195

4° S. 129° E.

n. sp.

n. g.

1

Antheomorphida;

Aiifheomorphe

elegans

2900

244

35° N. 169° E.

n. sp.

n. g.

3

Antheadse

Comadis

flagellifera

25

30° S. 20° E.

1

Tealidag

Tealia

bunodiformis

Shore.

37° S. 12° AY

n. sp.

3

n

Leiotealia

nymphcea

120

149

49° S. 70° E.

1

Paractida;

Dysactis

crassicorn is

10

312

53° S. 70° W.

n. sp.

1

>)

n

a

55

313

52° S. 68° W.

n. sp.

4

n

>>

rhodora

55

313

52° S. 68° W.

2

»»

Paradis

tubidifera

1875

237

34° N. 140° E.

n. sp.

2

n

n

excavata

1375

300

33° S. 78° W.

n. sp.

,

1

j»

Tealidium

cingulatum

1800

158

50° S. 123° E.

n. sp.

.

1

11

Ardholoba

reticulata

55

313

52° S. 68° W.

3

n

Ophiodiscus

anwulatus

2160

299

33° S. 74° W.

ii. sp.

n. g.

4

»j

n

sidcatus

1375

300

33° S. 78° W.

n. sp.

n. g.

1

Liponeniidse

Polyriphcmia

tnberosa

565

235

34° N. 138° E.

n. sp.

n. g.

20

>>

Polystomidium

patens

1825

296

38° S. 88° W.

n. sp.

n. g.

1

11

Liponema

multiporum

1875

237

34° N. 140° E.

n. sp.

n. g.

1

Sagartidse

Sagartia

sp. (?)

360

194

4° S. 129° E.

1

n

Calliadis

polypus

18

208

11° N. 123° E.

3

)»

11

n

17° N. 27° AY

6

n

Cereus

spiinosus

1950

157

53° S. 108° E.

n. sp.

1

n

a

»

1875

237

34° N. 140° E.

n. sp.

4

n

Phellia

pedinata

147

307

49° S. 74° W.

n. sp.

1

>»

ii

*P- (?)

1000

"

1

»j

Bunodes

minuta

1600

147

46° S. 48° E.

n. sp.

.

]

Amphianthidre

Stephanadis

tuberculoid

345

232

35° N. 139° E.

n. sp.

n. g.

1

>>

ii

abyssicola

1350

46

40° N. 66° W.

n. sp.

n. g.

2

»

Ampliianthus

bathybium

2300

241

35° N. 157° E.

n. sp.

n. g.

1

Ilyanthidae

Halcarnpa

davus

25

149

49° S. 70° E.

2

n

ii

n

120

149

?>

1

Sicyonidas

Sieyonis

crassa

1600

147

46° S. 48° E.

ii. sp.

n. g

1

Polyopida;

Polyojris

striata

2160

299

33° S. 74° W.

n. sp.

n. g.

1

Monaulidae

Scytnplwrus

striata.-;

150

150

52° S. 71° E.

n. sp.

n. g.

•)

Zoanthido?

Zoaid/ius

sp. (1)

1

n

Epizoanthus

parasiticus

565

235

34° N. 138° E.

o

Sphenopidaa

Spihenoptts

arenaceus

n. sp.

1

Cerianthidee

Cerianthus

americanus

13

321

35° S. 55° W.

1

Poiponia

elongata

2600

160

42° S. 134° E.

n. sp.

n. g.

o

...

ii

robusta

1875

237

34° N. 140° E.

n. sp.

n. g.

1

Note. — The reader is reminded that this is not a complete list of the Challenger Actinia;. A number of
specimens, which did not reach Professor llertwig till after this Memoir was in type, will be described in a
Supplementary Report. — J. M.

REPORT ON THE ACTINIA IMA. 131

Concluding Remarks.

In the Introduction I have given a sketch of the structure of the Actiniaria, and
also at the same time a short summary of the most important morphological results
furnished by the Challenger material ; all that remains is for me to discuss how far the
results of the Challenger expedition have furthered our knowledge of the manner in which
the group in question is distributed. I have therefore made out a tabular survey
(p. 130) of the Actiniae described and their habitats, and have also stated whether or
not they are new species and genera. It follows, of course, that I have only enumerated
as new, such species as have been actually described for the first time by Moseley and
myself, whilst I have included among the known animals those forms to which, since we
know their anatomy more thoroughly, it has been necessary to give new names, especially
new generic names.

The table in question gives no determinate results as to the geographical distribution
of the animals; it was, indeed, evident from the first that the Challenger material was
neither sufficient nor suitable for this purpose. The number of hauls made by the
dredge was utterly disproportioned to the vast tracts traversed by the ship in her voyage
round the world; the individual faunatic regions especially have been very irregularly
examined. As the ship was mostly on the high seas, the coasts, which would have
furnished the richest spoils, were of necessity almost entirely neglected, and in this way
we only find one littoral species in the list.

On the other hand, we must take into special consideration the manner in which the
Actinise are distributed in the different depths of sea. How far is the number of the
Actinias diminished by the increase of the depth ? How far does the deep-sea fauna
vary from the fauna of the coasts and the shallows ? Has life in the depths exercised,
as in other cases, a visible influence on the organisation of the animal ? These are
questions which may be partially solved from the tolerably wide range of material furnished
by the Challenger collection.

As a rule the number of the Actinias decreases as the depth increases; up to the present
they have not been observed even in the Challenger expedition at a depth of over 2900
fathoms, though the decrease does not take place so rapidly as might be expected. In
proof of this I contrast the results given by the hauls with the dredge in 10-500 fathoms,
with those in 500-2900 fathoms. The net was let down ninety-seven times in depths
of 10-500 fathoms, and eleven times with some result, i.e., with the capture of some
twenty specimens distributed over thirteen different species. There were one hundred and
sixty-five hauls with the dredge at depths of 500-2900 fathoms, fourteen of these fur-
nished about sixty specimens, representing twenty-one different sjjecies. These numbers
caimot of course be compared off hand, as the hauls made by the dredge in great depths

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

lasted much longer, and consequently extended over a larger tract, but at the same time
we can sec from this that the deep-sea Actinias are by no means exceptionally rare.

The relative abundance of the Actinias among the deep-sea fauna is shown by the
fact that several species and several specimens of the same species were not unfrequcntly
found at the same station. Station 235 furnished the largest number of individuals, viz.,
twenty specimens of Polysiphonia tuberosa and two colonies of Epizoanthus parasiticus
were taken at a depth of 565 fathoms. Stations 237 and 300 were distinguished by the
diversity of the forms dredged ; at the former four specimens of Cereus spinosus, two of
Paractis tubulifera, one of Porponia robusta, and one of Liponema rmdtiporum were
taken at a depth of 1875 fathoms, at the latter one Corallimorphus profundus, one Par-
actis excavata and one Opjhiodiscus sulcatus were taken at 1375 fathoms. The following
stations yielded also good results : — Station 299 ; depth, 2160 fathoms ; one Opiliioddscus
annulatus and one Polyopis striata. Station 157 ; depth, 1950 fathoms ; one Cereus
spinosus and one Corallimorphus rigidus. Station 147 ; depth, 1600 fathoms ; one
Bunodes minuta and one Sicyonis C7nssa.

The stations in shallow water are far behind as regards the results of the dredgings.
The only stations worthy of special mention are Station 143, depth 120 fathoms, which
contributed two Halcampa clavus and one Leiotealia nymphcea to the Challenger
material; and Station 313, depth 55 fathoms, which contributed three Antholoba
reticulata, four Dysactis crassicornis, and two Dysactis rhodora.

As regards the relation in which the fauna of the different depths stand to one another,
it may already be safely asserted that the greater the depth, the more the fauna varies
from that of the coast. I will make only two divisions, and compare, on the one hand,
the Actiniae from 10-500 fathoms, and on the other, the Actinias from 500-2900 fathoms
with the known forms essentially belonging to the coast. The first region gives on the
whole thirteen species and twelve genera, of which five species and two genera (Scytophorus
and Steplianactis) are new. The remaining twenty-one species and seventeen genera
belong to the second region (two genera, Phellia and Steplianactis, are represented in
both divisions), of which not less than twenty species and eleven genera are new. The
depths of 500-3000 fathoms are therefore inhabited by entirely different Actiniae, as even
the only species which cannot be considered as new, Ep>izoanthus parasiticus, approached
the first region, as it was taken at a depth of 565 fathoms.

The varying character of the deep-sea fauna leads us to the third question already
started, viz., has life in the great depths a visible influence on the organisation of the
Actinias % This influence can be distinctly recognised in many forms, and is shown by the
nature of the tentacles which have undergone retrograde formation, and are transformed
first into tubes, and afterwards into simple openings in the oral disk. In Paractis
tubidifera (depth 1875 fathoms) the tentacles have the same constitution as in the
majority of Actinias, except in one point, that the terminal opening, which is usually

REPORT ON THE ACTINIARIA. 133

small or entirely wanting, gapes widely. In Polysiphonia tuberosa (565 fathoms) the
tentacles have become short, slightly movable, wide-mouthed tubes; in Siryouis crassu
(1600 fathoms) they are small, wart-like rings, and in Potystomidiwm patens (1825
fathoms) and Polyopis striata (21 GO fathoms) the walls have almost entirely disappeared,
so that the terminal opening forms a fissure in the oral disk, the lasl remains of the
tentacle being represented by a circular margin surrounding the fissure, and so we come
finally to the genus Liponomia (1875 fathoms), in which the points at which the
tentacles were actually placed are merely indicated by openings in the oral disk. Of
the twenty-one forms from 500-3000 fathoms here described, no less than six species
have therefore undergone modifications of the tentacles in the same sense, whilst it has
never been observed in a single one of the forms of the coast fauna, which greatly exceed
the deep-sea fauna in number.

The view that the retrograde formation of the tentacles is connected with life in
greater depths is not only supported by the fact observed, that the character is limited
in its distribution to the deep-sea Actiniae, but also by the way in which it
appears in the different groups of Actinise. The six forms named in the last paragraph
show conditions allied to those in families of Actiniae lying widely apart from one another.
Of the three genera united as Liponemidse, IAponema comes near the Discosomidse, as
its stomidia may be divided into principal and accessory stomidia ; Polystomidiwm patens
resembles the Antheadse in having an endodermal muscle and marginal spherules, and
Polysiphonia with its mesodermal circular muscle resembles the Paractidse, to which Par-
actis tnbuUfera undeniably belongs. It might therefore perhaps be advisable to do away
with the family Liponemidse, and to distribute its members among the Discosoniidse,
Antheadae, and Paractidae. Finally, Sicyonis crassa and Polyopis striata vary entirely
from other Actinias, and are at the same time forms which differ entirely one from another.
It is most probable that a character which appears in forms which vary so remarkably,
but exist under the same conditions, is the consequence of these conditions of existence.

There is another point in the mode of life of the deep-sea Actiniae which seems to me
to favour the transformation of the tentacles into tubes and openings. The nutriment of
the deep-sea animals probably consists chiefly of material which is already disintegrated,
and of a soft nature when obtained. The animals often ingest sand, impregnated with
nutriment, from which they extracl what is digestible; at least I have repeatedly found
the interior of the deep-sea Actinia; full of mud. In such a mode of nutrition the long
prehensile tentacles would not be of the same use as they are in the littoral Actinia', which
lie in wait for booty, whilst on the other hand it would be a decided advantage to the
animals to be furnished with numerous inhalent tubes and openings through which they
can absorb semi-liquid nourishment. This then is the advantage of the stomidia and
tubular tentacles.

The retrograde formation of the tentacles is by no means the only point to be taken

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

into consideration in the varying character of the deep-sea Actiniae, the position of the
septa being equally important. The arrangement of the septa typical of the Hex-
actinia) is only present in thirteen genera, among which I reckon Ophiodiscus and Pohj-
stomidium, in which we meet with the differentiation of muscular and genital septa which
is otherwise unknown, and the genera Stephanactis and Amphianthns, in which we find
some approach to the Antipatharia. The other four genera differ from one another as
well as from the Hexactinise in the arrangement of the septa. They swell the number
i if the varying forms represented in shallow water by the Zoanthese, Cerianthese, and
Edwardsise, and therefore seem to indicate that the diversity in the structure of the
Anthozoa was formerly much greater than it is at present, and that the remains of this
diversity have been more extensively preserved in the depths of the sea than in the
shallow waters. In this way we can recognise peculiarities in deep-sea Actinias which
are common to the whole deep-sea fauna.

TABLE OF CONTENTS.

Introduction, .

Special Portion — Actisiaria,
I. Hexactini.e, .
CorcdlimarpMdve,
Corallimorphus, .

( 'oraUimorphus rigidus,

('iirtll/iiiiiirji/iiiK prn/ini'liis,

Antheomorphidas,

Antheomorpke, .

Antht omorphe elegans,
Antheadce,
Comactis,

Comactis Jtagt ttifera,

Teuliild',

Tealia, .

Tallin biiiwdi/iirmix,
Leiotealia, . :

Lriotffilin nyvijilimu,
Puradidce, .
Paraetis,

I'tli-ttt-tix c.irnrnfii, .

Dysactis,

Dysactis cras&icornis,
Dysactis rhodora, .

Teal ill in in,

Teuliiliiim cingidatum,
Antholoba,

Antholoba reticulata,
Ophiodiscits,

O/iltiotlixciix anitul'itii*,

Ophiodiscus sulcatum,
Liponemidix, .
Polysiphonia,

Polysiphonia tuberosa,
Polystomidium, .

Polystomidium patens,
Sagartidce,
Sagartia,

Siiijiirtiii .</< (!)

PAGE

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20
20
21
21
23
28
29
30
30
31
32
32
34
35
35
37
38
•II
41
41
44
44
49
51
51
53
53
56
57
til
63
63
63
67
67
70
72

136

THE VOYAGE OF H.M.S. CHALLENGER.

I. Hexactini.e, — continued.
Calliactis,

Calliaetis polypus, .
Cereus, .

Cereus spinosus,
Ph cilia, .

Phellia pectinata,
Bunodes,

Bunodes minuta,
Amphianthidce,

Sfr/iJimilliiis,

Stephanactis tubercidata,

Stephanactis abyssicola,
AmpManthus, .

Amphianthus bathybium,
Hyanthidce, .
Halcampa,

Halcampa clavus, .

II. PARACTINIiE,

Sicyonidce,
Sicyonis,

Sicyonis crassa,
Polyopidm,
Polyopia,

Polyopia striata,

III. Monaule^e,

Monaulidce, .
Scytophorus,

Scytophorus striata*,

IV. EDWARDSI.E,
V. ZOANTHE.E,

Zoanthidce, .
Zoanthus,

Zoanth us sp (1)
Epizoanthus,

Epizoanth us parasiticus,
Splienopidm,
Sphenopus,

Sphenopus arenaceus,
VI. Cerianthe^:,
Cerianthidce, .
Cerianthus,

Cerianthus american us,
Appendix, ....
Porponia,

Porponia elongata, .
Porponia robusta, .
Phellia sp (?), Paractis tubulifera, Liponema multiporum,
Tabular Survey,
Concluding Remarks,
Explanation of Plates.

page
73
74
76

76

80

81

83

84

86

87

88

90

91

91

92

92

92

97

97

98

98

101

101

101

104

104

104

104

107

109

111

111

111

116

116

120

120

120

123

123

123

123

125

125

125

127

128

130

131

PLATE I.

PLATE I.

n Acontia.

h M'-si'iiti'rir filaments.

c Stomata in the sopta,
c1 Perioral stomata.
<• '- Marginal stomata.
eu Cuticle

,/ Glandular streaks of the mesen-
teric filamenl

« Ciliated streaks ol the mesenteric
filaments.
■ h Ectoderm.
en Endoderm.

g I! iproductive organs.

h Septa, rh Directive septa.

i * Iral disk.

The lettering is the same in all the figures.

k Wall.
I Pedal disk.
in Muscles.
vim. Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Ketractor.
mp Parietobasilar muscle.
ml Transverse muscles.
iiir Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
mt Circular muscle of the wall.
me Mesoderm.
n Urticating cells.
o Ovieells.

All statements given as to magnifying powers have reference to Zeiss's system.

iv. l. Oc. 2.

a1 6 10

A 55 70

C 95 125

A with unscrewed front lens (uuscr. A) magnifies with Oc. 1

;» Filaments] apparatus of the ovieells.

p1 Process of the ovicell.

p'2 Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.

s; Lappets of the oesophagus.

t Tentacles and the openings homolo-
gous with them.
I. ' Principal tentacles.
t2 Accessory tentacles.

v Openings of the pedal disk.

The magnifying powers amount to

Oc. 1. Oc. 2.

I) ...

F ...
J ...

195 240

410 550
470 530

Oc. 1

: 30 times

with Oc. 2 : 40 times.

All the figures are of natural size.

Fig. 1. Porponia donga fa.

Fig. 2. Porponia elongata, opened by a longitudinal incision ; and the pedal disk split up by
repeated radial incisions. In the lettering on the plate for so read sr.

Fig. 3. Cereus spinosus.

Fig. 4. Cereus spinosus; the half of a sextant prepared by cutting into separate pieces; in the left-hand
portion one of the principal septa (A1 ) reaching to the oesophagus, with mesenteric filament and acontia
but without reproductive organs ; then follow a pair of septa of the fourth order (A4) and a pair of
septa of the third order (A3). The right-hand portion begins with the next following pair of small septa
of the fourth order (A4), and the much larger pair of septa of the second order (A-). All the accessory
septa have mesenteric filaments, acontia and reproductive organs, but do not reach the cesophagus
which hangs over them like an apron. A portion of the oesophagus has been removed in the left-hand
portion. Only the septa of the second order have coiled mesenteric filaments like the principal
septa. The three tentacles of the first row (t1) belong to the pairs of septa of the first to the third order,
the two of the second row (C2) to the pairs of septa of the fourth order, the four of the third row (t'i)
to the interseptal spaces.

Fig. 5. Cereus spinosus, opened by a longitudinal incision, which has run between a septum of the
third and a septum of the fourth order. The principal septa (A1) project with their coiled
mesenteric filaments below the lower margin of the cesophagus; the septa of the second order (A3)
project with smooth edges as their coiled mesenteric filaments, and their reproductive organs are
covered by the cesophagus ; the septa of the third order (A3) project with their reproductive organs.
The septa of the fourth order (A,4) are only visible at the side.

Fig. 6. Pa metis excavctta, one-third of the animal has been cut out in order to show the arrangement
of the oral disk and the corona of tentacles ; the section is directed so as to show two principal septa.

Fig. 7. Pliellia pectinata, opened longitudinally; the section runs between two principal septa of
the same pair; the principal septa project with their coiled mesenteric filaments below the oesophagus.

Fig. 8. Antheomorphe elegans.

Fig. 9. Antholoba reticulata.

Fig. 10. Porponia robusta ; fig. 10, a, a separate tentacle.

The Voyage of II M S Challenger

Actiniaria I'M.

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PLATE II.

PLATE II.

The lettering is the same in aU the figures.

a Acontia.

b Mesenteric filaments.
c Stomata in the septa.
c1 Perioral stomata.
c - Marginal stomata.
en Cuticle.

d Glandular streaks of the mesen-
teric filaments.
t Ciliated streaks of the mesenteric
filaments.
Ectoderm.
Endoderm.
Reproductive organs.
Septa, rh Directive septa.
Oral disk.

ek

k Wall.
I Pedal disk.
in Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
■ml1 Retractor.
inp Parietobasilar muscle.
int Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
vis Circular muscle of the wall.
me Mesoderm.
11 Urticating cells.
o Ovicells.

p Filamental apparatus of the ovicells.
p1 Process of the ovicell.
p2 Apical set of epithelial cells.
r Marginal spherules.
rh Directive septa.
.9 (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the cesophagu-;.
t Tentacles and the openings homolo-
gous with them.
t ' Principal tentacles.
t - Accessory tentacles.
v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system.

The magnifying powers amount to

Oc. 1. Oe. 2.

D 195 240

F 410 550

J 470 580

A with unscrewed front lens ('inser. A) magnifies with Oc. 1 : 30 times ; with Oc. 2 : 40 times.

a1
A
C

Oc. 1.

6

55

95

Oc. 2.
10

70
125

Fig. 1. Corallimorphus rigidus, seen from the oral disk ; one half the natural size,

Fig. 2. Corallimorphus profundus, seen from the pedal disk ; one half the natural size.

Fig. 3. ,, ,, seen from the oral disk ; one half the natural size.

Fig. 4. Lateral view of a portion of Corallimorphus rigidus ; natural size.

Fig. 5. Half of the pedal disk of Corallimorphus rigidus ; natural size.

Fig. 6. A septum with two tentacles, running out from the corresponding intraseptal
.-pace ; seen from the side of the intraseptal space.

Fig. 7. Polysiphonia tuberosa, lateral view ; natural size.

Fig. 8. Polysiphonia tuberosa, a part of the margin of the oral disk, the tentacles
having been cut away at their bases.

Fig. 9. Polysiphonia tuberosa, seen from the oral disk.

Fig. 10. Sphenopus arenaceus, bisected longitudinally ; natural size. (By an oversight
the microseptum has been omitted on the left-hand side.)

Fig. 11. Poly o pis striata, twice the natural size.

Fig. 12, a. Bunodes minuta, natural size.

Fig. 12, b. Bunodes mi until, bisected longitudinally.

Fig. 13. Stephanactis abyssieola, one and a half times the natural size ; seen from the
oral disk.

The Voyage of H.M.S."Cliallenger

Actiiuaria PI II

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PLATE III.

PLATE III.

The lettering is the same in all the figures.

a Aeontia.

k Wall.

// Filamental apparatus of the ovicells.

b Mesenteric filaments.

/ Pedal disk.

p l Process of the ovicell.

unata in the septa.

m Muscles.

p'2 Apical set of epithelial cells.

,■ I Pi rioi '1 stomata.

m ni Mesodermal muscles.

r Marginal spherules.

.■" Marginal stomata.

ml Longitudinal muscles of the septa.

rh Directive septa.

i iiticle.

ml1 Retractor.

s (Esophagus.

d Glandular streaks of the mesen-

mp Parietobasilar muscle.

so Openings of the oesophagus into

teric filaments.

mi Transverse muscles.

the radial chambers.

e Ciliated streaks of the mesenteric

mr Radial muscles of the oral disk

sr (Esophageal grooves.

filaments.

and longitudinal muscles of the

sz Lappets of the oesophagus.

ck Ectoderm.

tentacles

t Tentacles and the openings homolo-

en Endodenn.

ms Circular muscle of the walh

gous with them.

g Reproductive organs.

me Mesoderm.

t 1 Principal tentacles.

h Septa, rh Directive septa.

n Urticatiug cells.

t 2 Accessory tentacles.

i Oral disk.

o Ovicells.

v Openiugs of the pedal disk.

All statements given as to magnifyii

lg powers have reference to Zeiss's system.

The magnifying powers amount to

Oc. 1. Oc. 2.

Oc. 1. Oc. 2.

a1

6 10

D

... 195 240

A

55 70

F

... 410 550

C

95 125

J

... 470 ;.-"

A with unscrewed front lei

is (uuscr. A) magnifies with Oc. 1 : 30 times ; with Oc. 2 : 40 times.

Fig. 1. Halcampa clavus, bisected longitudinally so that the plane of division has
opened two intraseptal spaces; twice the natural size.

Fig. I, a. Half of the upper end of the body seen from the oral side; tentacles
bent inwards ; twice the natural size.

Fig. 1 , b. Upper end of the body with expanded tentacles ; twice the natural size.

Fig. 2. Eplzoanthus parasiticus ; natural size.

Fig. 3. Tealidium cingulatum, in a contracted condition, seen from the upper end
of the body ; twice the natural size.

Fig. 4. Halcampa clavus ; natural size.

Fig. 5. Comactis jlagellifera ; twice the natural size.
Scytophorus striatus; natural size.
Stephanactis tuberculata, lateral view ; natural size.

a. Stephanactis tuberculata, from the oral side ; natural size.

b. Stephanactis tuberculata, lateral portion of the body with the oesophageal

Fig.

Fig.

Fig-
Fig.

groove.

Fig.

Fig.

Fig

Fig.

6.

7.
7,
7,

8. Ophiodiscus sulcatus ; natural size; greatly restored.

9. A colony of Eplzoanthus parasiticus, divided longitudinally ; natural size.

10. Pedal disk of Halcampa clavus detached and seen from the inside. A, Oc. 1.

11. Amphianthus bathybium, seen from the surface; natural size.
Fig. 11, a. Amphianthus bathybium, a piece of the wall; slightly enlarged.

Fig. 11, b. Amphianthus bathybium, the margins of the pedal disk enclosing the
Mopsea; slightly enlarged.

Fig. 11, c. Amphianthus bathybium, lateral view ; natural size.

Fig. 12. Individual of a colony of Epizoanthus, opened longitudinally, and expanded ;
twice the natural size.

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PLATE IV.

PLATE IV.

The lettering is the same in all the figures.

a Acontia.

b Mesenteric filaments.

c Stomata in the septa.
c l Perioral stomata.
c ' Marginal stomata.
cu Cuticle.

d Glandular streaks of the mesen-
teric filaments.

t Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

g Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
m Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
mt Transverse muscles.
inr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ms Circular muscle of the wall.
me Mesoderm.
n Urticating cells.
o Ovicells.

All statements given as to magnifying powers have reference to Zeiss's system.

Oc. 1. Oe. 2.

a1 6 10 D

A 55 70 F

C 95 125 J

p Filamental apparatus of the ovirells.
p ' Process of the ovicell.
p2 Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr Oesophageal grooves.
sz Lappets of the oesophagus.

t Tentacles and the openings homolo-
gous with them.
t1 Principal tentacles.
t - Accessory tentacles.

v Openings of the pedal disk.

The magnifying powers amount to

Oc. 1. Oc. 2.

,.. 195 240

.. 410 550

... 470 bid

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times; with Oc. 2 : 40 times.

Sicyonis crassa.

Fig. 1. Transverse section through the upper end of the wall and the circular muscle
situated there. Ten times the natural size, but drawn with unscr. A, Oc. 2. On the
right hand side of the figure for ek read en.

Fig. 2. A sector of the pedal disk ; natural size.

Fig. 3. Longitudinal section through the wall of a wart-like tentacle. Unscr. A,
Oc. 2.

Fie. 4. The entire animal, seen from the oral side ; natural size.

Fig. 5. Transverse section through the basal portion of a tentacle ; about six times
the natural size.

Fig. 6. Part of a transverse section through the radial muscles of the oral disk.
D, Oc. 2.

Fig. 7. Part of a transverse section through the circular muscle ; enlarged more than
the preceding. D, Oc. 2.

Fig. 8. Transverse section through the oral disk, and insertion of a septum.
Unscr. A, Oc. 2.

Fig. 9. Septum ; natural size.

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PLATE V

PLATE V.

The lettering is tho same in nil tho figures.

a Acontia.

i Mesenteric filaments.

c Stomata in the septa.
c1 Perioral stomata.
c • Marginal stomata.
cu Cuticle.

d Glandular streaks of the mesen-
teric filaments.

c Ciliated streaks of the mesenteric
filaments.
eh Ectoderm.
en Endoderm.

■I Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

I- Wall.
I Pedal disk.
m Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
mi Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
vis Circular muscle of the wall,
me Mesoderm.
n Urticating cells.
o Ovicells.

All statements given as 10 magnifying powers have reference to Zeiss's system

Oc. 1. Oc. 2.

a1 6 HI n

A 55 70 F

C 95 125 J

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times; with Oc

p Filamental apparatus of the ovicells.
p ' Process of the ovicell.
p'z Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

.i (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the oesophagus.

t Tentacles and the openings homolo-
gous with them.
t ' Principal tentacles.
t1 Accessory tentacles.

o Openings of the pedal disk.

The magnifying powers amount to

Oc. 1.

Oc. 2.

195

240

410

550

470

5d0

with Oc.

2

: 40 times

Polystomidium jxitens.

Fig. 1. The portion of the oesophagus, contiguous to the labial margin, with the
openings leading into the radial chambers ; three times the natural size.

Fig. 2. Septum with pedal disk, wall, oral disk, cesojihagus, and mesenteric filament ;
natural size.

Fig. 3. Half of the animal seen from the aboral side ; natural size.

Fig. 4. Transverse section through the oral disk, near the oral margin. C, Oc. 2.

Fig. 5. Transverse section through a mesenteric filament in the upper part of its
course. C, Oc. 1.

Fig. 6. The entire animal, seen from the oral side ; natural size. As the only
specimen sent for examination was greatly injured, some restoration has been necessary.

Fig. 7. Transverse section through the oral disk, near the stomidia. C, Oc. 2.

Fig. 8. Longitudinal section through the upper end of the wall, the circular muscle
running in it and a marginal spherule. Unscr. A, Oc 2.

Fig. 9.

Longitudinal section through the circular muscle. D, Oc. 2.

Fig. 10. Longitudinal section through the lower end of the wall. A, Oc. 2.
Fig. 11. Horizontal section through the circular muscle. A, Oc. 2.
Fig. 12. Transverse section through a septum. Unscr. A, Oc. 2.

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PLATE VI.

PLATE VI.

The lettering is the same in all the figures.

a Acontia.

b Mesenteric filaments.

c Stomata in the septa.
c ' Perioral stomata.
'- - Marginal stomata.
cu I 'uticle.

d Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

3 Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk,
m Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
mt Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ms Circular muscle of the wall.
me Mesoderm.
n Urticating cells.
o Ovicells.

All statements given as to magnifying powers have reference to Zeiss's system.

Oc. 1. Oc. 2.

a1 6 10 D

A 55 70 F

C 95 125 J

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times

p Filfmental apparatus of the ovicells.
p 1 Process of the ovicell.
p2 Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

s Oesophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the oesophagus.

t Tentacles and the openings homolo-
gous with them.
t 1 Principal tentacles.
t2 Accessory tentacles.

v Openings of the pedal disk.

The magnifying powers amount to

Oc. 1. Oc. 2.

.. 195 240

.. 410 550

.. 47o 580

with Oc. 2 : 40 times.

Fig.

1

Fig.

2

Fig.

3

Fig.

4

Fig.

5

Fig.

6

Transverse sections through different forms of the circular muscle.

Circular muscle of Cereus spiTiosus. a1, Oc. 1.

,, ,, Tealidium cingulatum. C, Oc. 2.

,, ,, Polysiphonia tuberosa. a1, Oc. 2.

,, ,, Tealia bunodiformis. C, Oc. 2.

„ „ Phellia pcctinata. a1, Oc. 2.

Comactisflagcllifem. C, Oc. 2.

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k

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■

PLATE VII.

PLATE VII.

The lettering is the same in all the figures.

\ imtiu.

k "Wall.

P Filaments! apparatus of the ovicells.

/, Mesenteric filaments.

1 Pedal disk.

p1 Process of the ovicell.

c Ktomata in the septa.

in Muscles.

/>• Apical set of epithelial cells.

• Pei ioi il Btomata.

mm Mesodermal muscles.

r Marginal spherules.

■ ■" M irginal stomata.

ml Longitudinal muscles of the septa.

rh Directive septa.

eu Cuticle.

mfl Retractor.

s (Esophagus.

d Glandular streaks of the mesen-

mp Parietobasilar muscle.

so Openings of the oesophagus into

teric filaments.

ml Transverse muscles.

the radial chambers.

t Ciliated streaks of the mesenteric

mr Radial muscles of the oral disk

sr Oesophageal grooves.

filaments.

and longitudinal muscles of the

s~ Lappets of the oesophagus.

c.k Ectoderm.

tentacles

1 Tentacles and the openings homolo-

en, Endoderm.

ms Circular muscle of the wall.

gous with them.

g Reproductive organs.

me Mesoderm.

t. l Principal tentacles.

h Septa, rh Dirootive septa.

11 Urticating cells.

t 2 Accessory tentacles.

i Oral disk.

o Ovicells.

v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system.

The magnifying powers amount to

Oe. 1. Oc 2.

Oc. 1. Oc. 2.

a1 6 in

D

... 195 240

A '.. 55 70

F

... 410 550

C 95 125

J

... 470 530

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 tim

cs ; with Oc. 2 : 40 times.

Leiotealia nymphcea (figs. 1-5).

Fig. 1. Transverse section through the oral disk. A, Oc. 2.

Fig. 2. Radial section through the anterior end of the body, the wall with upper
and lower [ms') circular muscles, and the oral disk with a tentacle. Unscr. A, Oc. 2.
For I in the lettering of the plate read t.

Fig. 3. Transverse section through the septum at about one-third the height of the
animal, passing perpendicularly through the parietobasilar muscle and longitudinal muscle.
A, Oc. 1.

Fig. 4. Half a transverse section of the upper circular muscle. C, Oc. 1.

Fig. 5. Septum ; natural size.

Dysactis crassicornis (figs. 6-12).

Fig. 6. Transverse section through a septum. A, Oc. 1.

Fig. 7. Transverse section through the upper end of the wall. Unscr. A, Oc. 2
diminished two-thirds.

Fig. 8. Part of a transverse section through the circular muscle, more highly mag-
nified. D, Oc. 1.

Fig. 9. Section through the circular muscle parallel to the course of the fibrillar.
A, Oc. 2.

Fig. 10. Transverse section through the oral disk of an old animal. Unscr. A, Oc. 2.

Fig. 11. Transverse section through the oral disk of a young animal. Unscr. A,
Oc. 2.

Fig. 12. Septum ; natural size. The circular muscle appears rather too large in the
drawing.

The Voyage of H.M.S.'lliallenger'

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Actiniaria I'l VII

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12.

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PLATE VIII.

PLATE VIII.

The lettering is the same in all the figures.

a Acontia.

b Mesenteric filaments.

c Stomata in the septa.
c1 Perioral stomata.
c ■ Marginal stomata.
rn. i 'uticle.

d Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

g Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
m Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the sept
mP Retractor.
mp Parietobasilar muscle.
mt Transverse muscles.
mr Radial muscles of the oral disl
and longitudinal muscles of tin
tentacles
ms Circular muscle of the wall.
///<■ Mesoderm.
n Urtieatiug cells.
o Ovicells.

p Filamental apparatus of the ovicells.
p 1 Process of the ovicell.
p2 Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

s (Esophagus.
so Openings of the (esophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the oesophagus.

I. Tentacles and the openings homolo-
gous with them.
t1 Principal tentacles.
t - Accessory tentacles.

v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zciss's system.

Oc. 1. Oc. 2.

a1 6 10

A 55 70

C 95 125

The magnifying powers amount to

Oc. 1. Oc. 2.

.. 195 240

.. 410 550

.. 470 580

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times; with Oc. 2 : 40 times.

D

F
J

Fig. 1. Transverse section through the wall of Phellia pectinata. D, Oc. 2.

Fig. 2. Transverse section through the directive septa of Phellia pectinata below the
oesophagus. A, Oc. 2.

Fig. 3. Part of a transverse section through the longitudinal muscular swelling
(retractor) of a septum of Tealia bunodiformis.. C, Oc. 2.

Fig. 4. Longitudinal section through the wall of Tealia bunodiformis with endo-
derrnal saccules. A, Oc. 2.

Fig. 5. Part of a transverse section through the oesophagus, the wall, the directive
septa, and the adjoining septa of Tealia bunodiformis. a1, Oc. 1.

Fig. 6. Transverse section through the wall of Cereus spinosus. Fig. a, a portion
of the cuticule, drawn out like a tube. D, Oc. 2.

Figs. 7, 8. Portions of the circular muscle of Tealidium cingulatum, taken at different
points. J, Oc. 2.

Fig. 9. Endodermal muscles of the oral disk of Comactis flagellifera. D, Oc. 2.

Fig. 10. Portion of a transverse section through the circular muscle of Phellia
pectinata. D, Oc. 1.

The Voyage of II M.S. CJi Jlei

8.

■ . . ■

■

PLATE IX,

PLATE IX.

The lettering is the same in all the figures.

a Acontia.

b Mesenteric filaments.

c Stomata in the septa.
c ' Perioral stomata.
c * Marginal stomata.
cu Cuticle.

d Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

g Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
in Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
nit Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ins Circular muscle of the wall.
me Mesoderm.
11 Urtieatiug cells.
o Ovicells.

p Filamental apparatus of the ovicells.
pl Process of the ovicelL

p- Apical set of epithelial cells.
r Marginal spherules.
rh Directive septa.
s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
9z Lappets of the oesophagus.
t Tentacles and the openings homolo-
gous with them.
t ' Principal tentacles.
t- Accessory tentacles.
v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system. The magnifying powers amount to

A

c

Oc. 1.

6

55

95

Oc. 2.

10

70

125

D

F
J

Oc. 1.

195
410
470

Oc. 2.
240
550
530

A with unscrewed front lens (.unscr. A) magnifies with Oc. 1 : 30 times ; with Oc. 2 : 40 times.

Polysiphonia tuberosa (figs. 1-10).

Fig. 1. Transverse section through the pedal disk, showing the muscular fibres which
pass on to the furrows. A, Oc. 2.

Fiii. 2. Transverse section through a tentacle bulb, a1, Oc. 1.

Fig. 3. Horizontal section through the pedal disk. The upper part of the diagram is
near the outer surface; the lower shows the section passing transversely through the
bases of two septa. A, Oc. 2.

Fig. 4. Radial section through the pedal disk. C, Oc. 2.

Fig. 5. Pedal disk, natural size, seen from the lower side ; about one-sixth of it shown.

Fig. 6. Transverse section through the tentacle near the point, a1, Oc. 1.

Fig. 7. Part of a transverse section through the pedal disk (fig. 1) more highly
magnified. C, Oc. 2.

Fig. 8. Tentacles seen from the side ; natural size.

Fig. 9. A tentacle divided longitudinally ; natural size.

Fig. 10. Bottom of a radial furrow of the pedal disk, with the adjacent muscular
fibres ; seen in transverse section. C, Oc. 1.

Corallirnorjphus rigidus (figs. 11 and 12).
Figs. 11 and 12. Transverse sections through the wall.

-4 .

PLATE X.

PLATE X.

The lettering is the same in all the figures.

i icontia.

b Mesenteric filaments.

r Stomata in the septa.

t l Perioral stomata.

■' Marginal stomata.
cm ' 'utiele.

(I Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ck Ectoderm.
en Endoderm.

g Reproductive organs.

h Septa. rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
m Muscles.
7/ini Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
ml Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ins Circular muscle of the wall.
mc Mesoderm.
n Urticating cells.
o Ovicells.

p Filamental apparatus of the ovicells.
p1 Process of the ovicell.
p2 Apical set of epithelial cells.
r Marginal spherules.
rh Directive septa,
s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the oesophagus.
t Tentacles and the openings homolo-
gous with them.
I ' Principal tentacles.
t 2 Accessory tentacles.
v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system. The magnifying powers amount to

Oc. 1.

a' 6

A 5o

C 95

A with unscrewed front lens (unscr. A) magnifies with 0

)c. 2.

Oc. 1.

Oc. 2.

in

D ... .

.. .. 195

240

70

F ... .

410

550

125

J ... .

470

580

1 : 30 times ; with Oc. 2 : 40 times.

Oplilodiscus annulatus (figs. 1-10).

Fig. 1. A portion of the animal, seen from the side ; magnified a little.

Fig. 2. Transverse section through a tentacle near the base. Unscr. A, Oc. 2.

Fig. 3. A portion of the animal seen from the oral side ; natural size.

Fig. 4. A principal septum with the two adjoining genital septa; magnified a little.

Fig. 5. Transverse section through the oral disk at the insertion of a septum. A,

( )r. 2.

Fig. 6. Transverse sections through different parts of the circular muscle : a through
the upper part, 8 through the lower end. Unscr. A, Oc. 2.

Fig. 7. Portions of the circular muscle, more highly magnified ; a from the upper, /3
from the lower end. D, Oc. 2.

Fig. 8. Pseudo-tentacle, slightly magnified.

Fig. 9. Some terminal branches of the pseudo-tentacle, ten times the natural size.

Fig. 10. Longitudinal section through a branch of the pseudo-tentacle. J, Oc. 1 ;
and reduced one half.

Antholoba reticulata (figs. 11 and 12).

Fig. 11. Transverse section through the circular muscle. D, Oc. 2.
Fi«\ 12. Transverse section through the oral disk. C, Oc. 1.

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PLATE XL

a Aeontia.

i mesenteric filaments.

c Stomata in tho septa.
.•' Perioral stomata.
c- Marginal stomata.
eix i uticle.

d Glandular streaks of the mesen-
terie filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
i i Kndoderin.

;/ Reproductive organs.

A Septa, rh Directive septa.

i Oral disk.

PLATE XI.

The lettering is the same in all the figures.

k Wall.
I Pedal disk.
m Muscles.

mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
mP Retractor.
m/i Parietobasilar muscle.
int. Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ins Circular muscle of the wall.
me Mesoderm.
n Urticating cells.
o Ovicells.

/) Filamental apparatus of the ovicells.
p1 Process of the ovicell.
ji2 Apical set of epithelial cells.

r Marginal spherules.
rh Directive septa.

s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the oesophagus.

/, Tentacles and the openings homolo-
gous with them.
t l Principal tentacles.
t'2 Accessory tentacles.

v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system. The magnifying powers amount to

a'

A
C

c. 1.

Oc. 2.

6

10

55

70

95

125

D

F
J

Oc. 1.
195
410
470

Oc. 2.
240
550

580

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times ; with Oc. 2 : 40 times.

Pohjopis striata (figs. 1-12).
(Figs. 1-8, Unscr. A, Oc. 1.)

Fig. 1. Transverse section through the oral disk near the stomidia, corresponding to
line a in fio;. 6.

Fig. 2. Transverse section through the oral disk, rather more towards the centre,
corresponding to line ft.

Fig. 3. Transverse section through the oral disk, still more towards the centre,
corresponding to line y.

Fig. 4. Transverse section through the upper part of the oesophagus and the openings
lying in it.

Fig. 5. Transverse section through the oral disk, near the oral opening, corresponding
to line e.

Fig. 6. Surface view of a part of the oral disk. Unscr. A, Oc. 1, and reduced to one-
eighth.

Fig. 7. Transverse section through the oral disk, nearly midway between figs. 3 and
5, corresponding to line S.

Fig. 8. Transverse section through the lower part of two directive septa.

Fig. 9. Transverse section through a septum and the oral disk in the region of the
stomidia. A, Oc. 2.

Fig. 10. Eadial section through the oral disk, endodermal side. C, Oc. 2.

Fig. 11. The lower end of the body-wall a seen from the ectodermal side, /3 seen from
the gastric side, about twice the natural size.

Fig. 12. Septum with adjacent portion of the wall, oral disk and oesophagus ; natural

size.

Paractis excavata (figs. 13 and 14).

Fig. 13. Transverse sections through a tentacle, a at the point, b in the middle, c at
the base. Unscr. A, Oc. 1.

Fig. 14. Part of a similar transverse section more highly magnified. D, Oc. 1.

The Vavaife of H.Jf.S.'Clialleiiger"

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6.

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A< iini.iri.i l'l.XI

(k

ek

mr

PLATE XIT.

PLATE XII.

The lettering is the same in all the figures.

a Acorrtia.

b Mesenteric filaments

c Stomata in the septa.
c ' Perioral stomata.
c- Marginal stomata.
at Cuticle.

d Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

g Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
m Muscles.
mm Mesodermal muscles.
ml Longitudinal muscles of the septa.
ml1 Retractor.
mp Parietobasilar muscle.
■mt Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ms Ci rcular muscle of the wall.
me Mesoderm.
n Urticating cells.
o Ovicells.

All statements given as to magnifying powers have reference to Zeiss's system.

Oc. 1. Oc. 2.

a1 6 10 D

A 55 70 F

C 95 125 J

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times ;

p Filamental apparatus of the ovicells.
;> l Process of the ovicell.
p^ Apical set of epithelial cells.

)■ Marginal spherules.
rh Directive septa.

s (Esophagus.
so Openings of the cesophagus into

the radial chambers.
sr (Esophageal grooves.
sz Lappets of the cesophagus.

t Tentacles and the openings homolo-
gous with them.
I1 Principal tentacles.
t - xVccessory tentacles.

v Openings of the pedal disk.

The magnifying powers amount to

Oc. 1.

Oc. 2.

195

240

410

550

470

580

with Oc.

2 : 40 times

Corallimorplius rigidus. D, Oc. 2 (figs. 1-7).

Figs. 1-4. Young ovicells in the endoderm ; in figs. 2 and 3 two cells depicted in the
act of migrating into the mesoderm.

Fig. 5. Ovicells with filamental apparatus ; the epithelial cells of the filamental
apparatus still lie completely in the epithelium.

Fig. 6. Ovicells with filamental apparatus ; the epithelial cells of the filamental
apparatus migrating into the mesoderm.

Fig. 7. Ovicells with filamental apparatus.

Halcampa clavus. D, Oc. 1 (figs. 8, 9, 11).

Figs. 8 and 9. Two ovicells of different ages with the epithelial apparatus.
Fig. 11. Ovicells which lie partly in the endoderm, partly in the mesoderm.

Cereus spinosus (fig. 10).
Fig. 10. Transverse section through an acontium of Cereus spinosus. C, Oc. 2.

The Voyage of OLS .'Challenger.'

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Hu-
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Actii PI XII.

/'•

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p'

PLATE XIII.

PLATE XIII.

The lettering is the same in all the figures.

a Acontia.

k Wall.

p Filamental apparatus of the ovicells.

b Mesenteric filaments.

1 Pedal disk.

p ' Process of the ovicell.

c Stomata in the septa.

m Muscles.

p2 Apical set of epithelial cells.

c1 Perioral stomata.

mm Mesodermal muscles.

r Marginal spherules.

<■'- Marginal stomata.

ml Longitudinal muscles of the septa.

rh Directive septa.

cu Cuticle.

mP Retractor.

s (Esophagus.

d Glandular streaks of the mesen-

mp Parietobasilar muscle.

so Openings of the oesophagus into

teric filaments.

mt Transverse muscles.

the radial chambers.

e Ciliated streaks of the mesenteric

mr Radial muscles of the oral disk

sr (Esophageal grooves.

filaments.

and longitudinal muscles of the

sc Lappets of the oesophagus.

ek Ectoderm.

tentacles

t Tentacles and the openings homolo-

en Endoderm.

ms Circular muscle of the wall.

gous with them.

g Reproductive organs.

me Mesoderm.

(' Principal tentacles.

h Septa, rh Directive septa.

n Urticatiug cells.

t 2 Accessory tentacles.

i Oral disk.

o Ovicells.

v Openings of the pedal disk.

AH statements given as to magnifyi

lg powers have reference to Zeiss's system.

The magnifying powers amount to

(

)c. 1. Oc. 2.

Oc. 1. Oc. 2.

a1

6 10

D

... 195 240

A

55 70

F

... 410 550

C

95 125

J

... 470 580

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 tim

js ; with Oc. 2 : 40 times.

Fig. 1. Transverse section through the mesoderm, ectodermal epithelium, and cuticle
of Scytophorus striatus. D, Oc. 2.

Fig. 2. Longitudinal section through the pleated circular muscles of the wall at the
lower end of Halcampa clavus. A, Oc. 1.

Fig. 3. Transverse section through the body of Scytophorus striatus passing through
the oesophagus, a1, Oc. 1.

Fig. 4. Transverse section through the body of Halcampa clavus, passing through the
oesophagus, a1, Oc. 1.

Fig. 5. Section parallel to the surface through the pedal disk of Halcampa clavus.
C, Oc. 1.

Fig. 6. Transverse section through the pedal disk of Halcampa clavus. C, Oc. 1.

Fig. 7. Half a transverse section through the lower extremity of Halcampa clams.
a1, Oc. 1.

Fig. 8. Transverse section through the cuticle of Scytophorus striatus. D, Oc. 2.

Fig. 9. Septum of the first order of Aatholoba reticulata; natural size.

H.M.S.'(

.

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G.

PLATE XIV.

• •

PLATE XIV.

The lettering is the same iu all the figures.

a Acontia.

ft Mesenteric filaments.

c Stomata in the septa.
c J Perioral stomata.
c- Marginal stomata.
cu Cuticle.

d Glandular streaks of the mesen-
teric filaments.

e Ciliated streaks of the mesenteric
filaments.
ek Ectoderm.
en Endoderm.

;/ Reproductive organs.

h Septa, rh Directive septa.

i Oral disk.

k Wall.
I Pedal disk.
m Muscles.
mm Mesodermal muscle9.
ml Longitudinal muscles of the septa.
mP Retractor.
mp Parietobasilar muscle.
mt Transverse muscles.
mr Radial muscles of the oral disk
and longitudinal muscles of the
tentacles
ms Circular muscle of the walL
me Mesoderm.
n Urticatiug cells.
o Ovicells.

p Filamental apparatus of the ovicells.
p1 Process of the ovicell.
p- Apical set of epithelial cells.
r Marginal spherules.
rh Directive septa,
s (Esophagus.
so Openings of the oesophagus into

the radial chambers.
sr (Esophageal grooves.
gz Lappets of the oesophagus.
t Tentacles and the openings homolo-
gous with them.
t 1 Principal tentacles.
t'2 Accessory tentacles.
v Openings of the pedal disk.

All statements given as to magnifying powers have reference to Zeiss's system. The magnifying powers amount to

a1
A
C

Oc. 1.

55
95

Oc. 2.

10

70

125

D
F

J

Oc. 1.
195
410

470

Oc. 2.
240
550
580

A with unscrewed front lens (unscr. A) magnifies with Oc. 1 : 30 times ; with Oc. 2 : 40 times.

Zoanthus, sp. ? (figs. 1-4 and 6).

Fig. 1. Longitudinal section through the upper end of the wall and the circular
muscle running in it. Unscr. A, Oc. 2.

Fig. 2. Transverse section through the wall, oesophagus, niacrosepta and microsepta.
A, Oc. 2.

Fig. 3. Transverse section through an individual of a Zoanthus colony. The figure
is composite, the left-hand half representing a transverse section on a level with the
oesophagus, the right-hand half a transverse section situated rather further down.
a1, Oc. 2.

Fig. 4. Part of a transverse section through the wall. D, Oc. 2.

Fig. 6. Transverse section through a small individual of a Zoanthus colony, passing
through the oesophagus, a1, Oc. 2.

Ejnzoanthus 2'>cirasiticus (fig. 5).

Fig. 5. Part of a transverse section through the wall of Epizoanthus parasiticus.
D, Oc. 2.

Liponema multiporum (fig. 7).

Fig. 7. Marginal portion of the oral disk of Liponema multiporum ; twice the natural
size.

Sphenopus arenaceus (fig. 8).

Fig. 8. Transverse section through the wall of Splienopus arenaceus. D, Oc. 2.

rhe Voyage of li M S ( hallenSer

Actiniapia PI..\1\'.

THE

VOYAGE OF H.M.S. CHALLENGES

ZOOLOGY.

REPORT on the Tunicata collected during the Voyage of H.M.S.
Challenger during the years 1873-76. By William A. Herdman,
D.Sc, F.L.S., F.R.S.E., Professor of Natural History in University
College, Liverpool.

PART I.— ASCIDI.E SIMPLICES.

PREFACE.

This collection of Tunicata, entrusted to me for description by the late Sir C. Wyville
Thomson,1 was placed in my hands early in May 1879. As most of the specimens
were in muslin bags packed in large bottles, it was difficult to form a correct idea of the
size of the collection. When unpacked and arranged roughly in species it proved to be
much larger than had been at first estimated. Since then I have several times received
from Mr. Murray bottles of Tunicata which had been accidentally included in other collec-
tions, and specimens which had been overlooked in sorting out the different groups. The
pelagic forms taken in the tow-net (including the Pyrosomidae, the Appendiculariidaa, and
the Thaliacea) did not reach me till some time afterwards.

My first object was to separate the collection of fixed Tunicata into Simple, Social, and
Compound Ascidians. I then commenced to work through the first two of these groups in

1 I wish here to record my deep sense of indebtedness to Sir Wyville Thomson, for having given such an
important piece of work into my charge, and for the ever ready and valuable advice with which he aided me during
the first part of my investigations.

(ZOOL. CIIALL. EXP. PART XVII. — 1882.) E 1

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

detail ; and as the descriptions and plates of this part of the collection are now finished, and
it may be some months before those of the Ascidise Compositse and the Pelagic Tunicates
are completed, it is thought best to publish the Report upon the Ascidias Simplices
separately. The Bibliography, however, and some other parts of the Introduction, refer
to the whole group of the Tunicata.

The collection generally was in an excellent state of preservation ; but some few
specimens, with exceptionally solid tests, had suffered apparently from the apertures
having contracted so completely as almost to exclude the alcohol. The precaution of
making an incision in the test had been taken in the case of most of the large specimens.
Specimens of a few of the Compound Ascidians and Pelagic forms had also been preserved
in absolute alcohol.

The collection of Ascidiae Simplices consists of eighty-two species arranged in twenty
genera. Seventy-four of the species and nine of the genera were new to science.1 These
species added by the Challenger Expedition have not necessitated the formation of
a single new family. Although a number of new genera have been required, usually
for the forms from great depths, yet these have all found a place in one or other of the
four families already known. The new genera have in several cases been of great interest,
as they have demonstrated affinities between known forms, and have exhibited combina-
tions of characters necessitating in some cases a revision of the definitions of old genera,
and even affecting in one or two instances our ideas with regard to the characters of the
families.

In 1876 Professor Moseley described, in the Transactions of the Linnean Society, two
very remarkable Ascidians which he had investigated during the voyage of the Challenger.
The first of these, Hypobytliius calycodes, belongs to the family Ascidiidas ; the second,
Octacnemus bythius, seems to me to be nearer to the Thaliacea than to the Ascidiacea, and
consecpiently comes into the second part of this Report.

The new species are all illustrated and described in detail. Species previously known
are not figured, except in cases where they have been imperfectly described, or where the
Challenger specimens show some special feature.

1 Most of these new species were named and briefly described in my four Preliminary Reports upon the collection
read before the Royal Society of Edinburgh (see Proc. Roy. Soc. Ediii., Sessions 1880-82).

CONTENTS,

Introduction,
History,

Bibliography, .
Anatomy,

Description of the Species,
Ascidis Simplices,
Molgulidse,
Aseopi ra,
Molgula,
Eugyra,

Cynthiidae,

Bolteninae,

Boltenia,
Guleolus,

Comparison of the Species of Guleolus,
Fuwjulus, .

Cynthinse,
Microcosmus,
Cynthia,

Styeliiise,
Styela,
Bathyoncm,

Polycarpa,

Ascidiidse,

Corynaseidia,

Curella,

Abyssascidia,

Ascidia,

Paehychlcena,

Hypdbythvus,

Cicma,

Clavelinidae,

Eett inascidia,

Clavelina, .

fAGE

5

5
11
25

57
57
58
61
07
81

83

85

86

90

120

127

130
130
134

148
149
165
167

182
186
189
193
196
221
227
233

237
239
245

THE VOYAGE OF H.M.S. CHALLENGER.

Geographical Distribution, .

Bathymetrical Distribution,

Summary and General Remarks,

Index,

Explanation op the Plates,

List of Abbreviations,

page
249

267

275

289

295

295

INTRODUCTION.

There is no large work on the Tunicata as a class, nothing of the nature of a
revision of the group, to which one may refer for the results of the numerous memoirs and
widely scattered papers which have been written on particular forms and special points
in anatomy. It seems therefore almost necessary to give, as an introduction to the
description of so many new genera and species of Ascidians, an outline of the history of
the group, a full bibliography, and a short account of the anatomy and histology of the
principal forms.

HISTORY.1

The history of the literature of this, as of almost every other group of animals, extends
back to about 330 B.C., when Aristotle in his History of Animals gave, under the name
of Teihyum, a short account of a Simple Ascidian. He described briefly the external
appearance and the nature of the test, referred to the apertures and their inhalent and
exhalent functions, mentioned the mantle as a sinewy membrane lining the shell-like
substance, and evidently recognised the branchial and atrial chambers and the alimentary
canal — all the more important points in the macroscopic anatomy of the animal.

The only other writers of classical times who mention Ascidians are Pliny and -Mian,
and they seem to have made little or no advance upon the knowledge of Aristotle.

After this the record of Ascidiology takes a great leap over nearly fourteen centuries
— the dark ao-es of literature and science — and brings us to the middle of the sixteenth
century, when Bellonius and Rondeletius wrote treatises upon marine animals, some of
which we can recognise either from the figures or descriptions as Ascidians.

Durino- the next hundred years Aldrovandus, Avicenna, Gesner, Jonston, Redi, and
Sloane, wrote on Marine Zoology, and contributed more or less to the knowledge of the
Tunicata.

Schlosser first brought the Compound Ascidians into notice by his paper in the
Philosophical Transactions for 175G, containing a description of Botryllus, with some
observations by John Ellis. A few years later, A. Russel described and figured an
undoubted Boltenia from the coast of North America. Baster, shortly afterwards, in his
Opuscula Subseciva, described a species of Tunicate to which he gave the name Asddivm,
and compared its organisation with that of the oyster. Pallas suggested the union

1 As a rule only works of considerable importance are referred to in this outline of the history. The complete
titles and dates of these and other works on the Tunicata will he found under the authors' names in the Bibliography.

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

of Teihywm and Ascidium under one name, and this was afterwards effected by Linnaeus
(Sys. Nat., 12th ed.), who designated the genus Ascidia.

Bolten's papers on the remarkable form which bears his name were published in
1770 and 1771, and the observations of Gaertner, Forskal, Phipps, Pallas, Dicquemare,
Fabricius, and others, all of whom described and usually figured new species of Simple
Ascidians, appeared during the next ten years. The most important contribution of this
period (the end of the eighteenth century) was the work of 0. F. Midler. His Pro-
dromus was issued in 1776, and contained a considerable list of named species of Tunicates,
while his great work, the Zoologia Danica, gave most valuable descriptions and figures of
twenty species.

Bruguiere, in the Encyclopedic Methodique, collected all that had been done previously,
but added little that was new or important. His work, therefore, represents the state of
knowledge of the group up to the year 1800.

In the commencement of the present century valuable anatomical researches were
made by Schalk, Carus, and especially Cuvier, who arranged the Ascidians along with the
Mollusca under the name of Acephala nuda. At this period also, the genus Pyrosoma
was described first by Peron, and afterwards by Peron and Lesueur ; and the latter in
conjunction with Desmarest wrote a memoir upon the structure of Botryllus. But by far
the most important contributions of this period were the celebrated memoirs of Savigny,
pubbshed in 1816.. This author first satisfactorily elucidated the structure of the Com-
pound Ascidians, and distinguished them from the Alcyonarians with which they had
previously been confounded. His accounts of the different genera which he instituted, are
models of patient and careful research, and the accuracy of his descriptions and figures is
wonderful.

Savigny's memoirs upon the Simple Ascidians are no less remarkable. He broke the
group up into four great genera — Phallusia, Cynthia, Boltenia, and Clavelina — which
might almost be taken as types of the four families, Ascidiicke, Molgulidaa,1 Cynthiidae,
and Clavelmidse. Some of these genera he further divided, and these subdivisions are
in several cases now recognised as genera ; and finally he described and figured a large
number of new species. Lamarck, in his Histoire Naturelle, profiting by the anatomical
discoveries of Cuvier and Savigny, characterised a number of Ascidians, Simple as well as
Compound, and arranged them as a class, the Tunicata, intermediate between the Eadiata
and the Vermes.

Every year now brought new additions to our knowledge. Chamisso made his well-
known observations upon Salpa about this time, and first noticed the series of phenomena
afterwards more fully described by Steenstrup in 1842 as "alternation of generations;"
while a little later we have Kuhl and van Hasselt's investigations upon the heart of the
same form, resulting in the discovery of the alternation in the directions in which the
wave of contraction passes along the heart, and the blood flows in the vessels.

1 Taking Savigny's Cynthia dione as a Mohjula, which it probably is.

EEPORT ON THE TUNICATA. 7

In 182S Aiulouin and Milne-Edwards announced their discovery of the metamorphosis
through which the Ascidian passes in its development from the embryo to the adult
form. This was also independently discovered in the various groups of Tunicata at later
dates by Lister, Sars, Dalyell, van Beneden, Agassiz, Krohn, and Gosse.

The important works of Delle Chiaje, Lesueur, and Macleay also appeared at this time,
the latter adding considerably to our knowledge of the Bolteninse. A considerable number
of works of less importance, being chiefly descriptions of new species, appeared in the
second quarter of the century, the most notable being those of Lesson, Quoy and
Gaimard, Milne-Edwards and Audouin, Risso, and Ehrenberg. Broderip and Sowerby
first described the remarkable Chelyosoma, and Mertens his Oi/:<>jilnira, one of the
Appendiculariidse, about this time. Shortly afterwards (1831), some excellent observa-
tions upon Social and Compound Ascidians were made by J. J. Lister, and appeared in
the Philosophical Transactions. This author investigated the common vascular system
in a species which was afterwards named Perophora listeri by Wiegmann (1835).

The curious Pelonaia, a form allied to Styela, was discovered and brought before the
British Association by Goodsir and Forbes in 1840, and about this time Eschricht's
observations upon Salpse were published in Denmark, to be followed two years later by
his detailed account of the anatomy of Chelyosoma. This was also the date of Milne-
Edwards' " Observations sur les Ascidies Composees des cotes de la Manche," one of the
most important memoirs upon this group of the Tunicata.

In this country a number of short papers, chiefly by Goodsir and Forbes, Thompson,
Macgillivray, Carpenter, Allman, Peach, and Alder, made their appearance between 1840
and 1845. They contain descriptions of new species, and occasionally discussions upon
the systematic position and classification of the Tunicata.

In 1845 Carl Schmidt first announced the presence in the test of some Tunicata of tuni-
cine, a substance very similar to cellulose, and in the following year Lowig and Kolliker
confirmed the discovery, and made some additional observations. An important memoir
1 »y van Beneden on the embryology, anatomy, and physiology of Simple Ascidians appeared
in Belo-ium in 1847. In the following year the first part of Forbes and Hanley's British
Mollusca was published. This gave descriptions of all the known species of British
Ascidians, many of them figured, and contained a great deal of original matter. At the
same time Rupert Jones' article " Tunicata" in Todd's Cyclopaedia made its appearance :
an excellent summary of what had been done previously, and of the state of our knowledge
of the o-roup at the time. Alder's Catalogue of the Marine Mollusca of Northumberland
and Durham, published shortly afterwards added some new species to our British fauna.

About this time Huxley began his observations upon the pelagic Tunicates, and two
important papers by him appeared in 1851 in the Philosophical Transactions, one upon the
anatomy of Sal pa and Pyrosoma, and the other upon Appendicidaria and Dolwlwm.
Geo-enbaur, Vogt, H. Midler, Krohn, and Leuckart a few years later contributed further

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

observations, especially upon Doliolvm and Append icularia. In America, Stimpson
described a number of new species, both from the American coasts and frum the seas of
China and Japan. Dr. J. D. Macdonald now commenced his valuable series of observa-
tions upon Tunicata, both pelagic and fixed. He described many new species from
different parts of the world, including some most remarkable forms, such as Chondro-
stachys, and Diplosoma.

Bronn's " Thierreichs " (1852) contains the most complete revision of the entire group
which has yet been published. After a short history and a list of the principal works on
the subject, a complete and detailed account of the anatomy and embryology as known
at that time is given. This is followed by a tabular classification with diagnoses of the
orders, families, and genera ; the whole concluding with a section on the distribution of
the group.

Grube's observations upon tbe Fauna of the Island Lussin, containing descriptions of
some new or imperfectly known Ascidians, and Lacaze-Duthiers' paper upon Chevreulius,
previously described as Rhodosoma by Ehrenberg in 1828, appeared a few years later.

The following year (1866) was the date of the appearance of one of the most
important memoirs in the entire range of embryology, namely, Kowalevsky's "Entwicke-
lungsgeschichte der einfachen Ascidien." This was the first time that the Tunicata had
been treated according to modern embryological methods, and that the development of
the various organs had been worked out cell by cell, and their origin traced back to parti-
cular cell masses. Up to this jieriod all that was known of the process of development of
a Simple Ascidian was from Krohn's paper in 1852, on the embryology of Phallusia
mammillata, in which the various organs were described in the fully developed tailed
larva, but their process of development in the embryo was scarcely investigated. Hence
Kowalevsky worked upon comparatively fresh ground, and his remarkable memoir con-
tained results of the greatest novelty. He was the first to demonstrate the striking simi-
larity between the relations of the nervous system, the notochord, and the alimentary
canal in the larval Ascidian, on the one hand, and the vertebrate embryo on the other.
He also traced the development of the chief organs of the tailed larva from the segmented
ovum, and showed, in this case also, a certain similarity to the embryonic development
in a vertebrate. This pointed clearly to the fact that the Tunicata are closely allied
to the Vertebrata, and that the tailed larva represents the primitive or ancestral form from
which the adult Ascidian has degenerated ; and this led naturally to the view usually
accepted at the present day, that the group is a degenerated side branch from the lower
end of the vertebrate phylum.

Kowalevsky's paper naturally drew other investigators into the same field. One of
the most important of these was Kupffer, who first of all took up the subject with the
view of, if possible, disproving Kowalevsky's results, but was speedily converted, and
soon became one of the strongest supporters of the new views. He published several

KKPoKT ON TIIK TUXICATA. 9

important papers corroborating Kowalevsky's results in all essential points, though
differing from him in some minor details. Kowalevsky has since published several
other embryological papers, chiefly extending his discoveries to other groups of the
Tunicata.

Hancock took up the Ascidians of the British Seas, at first in conjunction with Alder,
who had already (1863) worked at the group. They described a number of new species,
and Hancock in 1868 published some of his anatomical observations in the Journal
of the Linnean Society. At the time of his death he was collecting material for a
Monograph upon the British Tunicata.

In 1871-72 Verrill described a number of new species and genera of Ascidians from
the coasts of North America.

In the following year Giard published a large work upon the Synascidia? containing the
descriptions of a considerable number of new species, and also many important anatomical
observations. About this time 0. Hertwig's paper on the structure of the test made its
appearance. This was by far the best paper that had yet appeared on this subject, and it
satisfactorily determined the structure of the different parts and their relations to one
another. The most important points have since been confirmed by Semper in his paper
on the presence of cellulose in the Ascidian test, published in 1875. A paper by B.
Hertwig, the brother of the above-named author, which also appeared in 1872, contains
a number of valuable anatomical observations, especially upon the structure of the
endostyle ; whfle, during the few years that had elapsed since Kowalevsky's and
Kupffer's first researches, many further details as to the embryology of Simple Ascidians,
and the process of gemmation in the Compound forms, had been obtained by the
investigations of Krohn, Metschnikoff, Kowalevsky, Stepanhoff, Kupffer, and others.

At this time also (1872) an important memoir by H. Fol, upon the Appendiculariidse
of the Straits of Messina made its appearance.

In 1874 Ussow's memoir upon the histology of the nerve ganglion and the neigh-
bouring organs was published in Russia. In this it is shown that the gland lying below
the ganglion has a duct which runs forwards to terminate in the so-called " olfactory
tubercle."

In this same year Lacaze-Duthiers commenced the publication of his important work
upon the Ascidiaa Simplices of the coast of France. His first part was anatomical. A
species of Molgula was chosen as a type, and all its organs were described with great
thoroughness and minuteness. Lacaze-Duthiers, however, throughout regards the Ascidian
as a modified Lamellibranch mollusc. His second part, published a few years later
(1877), contains a systematic description of the family Molgulidse. He introduces two
new genera, Anurella and Ctenicella, of which the former differs from Molgida chiefly
in the fact that its embryos never develope into tailed larva?, but undergo a modified
process of development. The species are all described with great minuteness, and are

(ZOOL. CHALL. EXP.-— PART XVII. — lSi^l'.) E 2

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

beautifully illustrated. Heller's " Uutersuchungen " commenced in 1874, and the last
part published (Abth. iii. 1) appeared in 1877. The work is devoted to a description
of the Simple Ascidians of the Adriatic and Mediterranean seas, and commences with an
account of the anatomy of Ascidia mentula. In the succeeding systematic part a number
of new species are described, most of them briefly, a few with a considerable amount of
mical detail. Kupffer's report upon the Tunicata collected by the German North Sea
Expedition contains descriptions of several new Simple Ascidians, and anatomical notes
upon some imperfectly known species.

An important paper by Fol, which appeared in 1874, must not be overlooked. It
gives an account of the structure and function of the endostyle, showing its glandular and
non-nervous nature.

In 1875 Kowalevsky's elaborate memoir upon the development of Pyrosoma was
published. Huxley had long before (1862) investigated this genus, and described the
remarkable " Cyathozooid " which gives rise to the first " Ascidiozooids " of the colony.
Kowalevsky's researches confirmed Huxley's discovery, and gave fuller details of some of
the stages.

In the same year Todaro's and Brooks' elaborate but in some points rather conflicting
accounts of the development of Salpa made their appearance.

In 1880 a paper appeared upon the Simple Ascidians of the seas of Denmark by
Traustedt, containing descriptions of a number of old and imperfectly described, and a few
new, species. It also settled some questions of priority in naming, and gave very full lists
of the synonyms of the species. A second paper by the same author has just appeared
(1S82), containing descriptions of some new West Indian species of Ascidiidse.

In 1881 a very important memoir by C. Julin was published in the Archives de
Biologic This paper gives the results of anatomical investigations into the condition of
the nervous system and some neighbouring organs in a few species of the Ascidiidse.
Julin corroborates Ussow's account of the relations of the subneural gland to the olfactory
or dorsal tubercle, and further declares that the latter organ is nothing more than the
complicated aperture of the duct from the gland, and that it has nothing whatever to do
with an olfactory or any other sensory function. Julin considers that the gland is homo-
logous with the pituitary gland of vertebrates, and that the duct and aperture into the
branchial sac represent the embryonic connection of the pituitary gland with the pharynx.
In a second paper published in 1882 Julin extends his observations to two other species
of Ascidia, and enunciates a theory suggested by Professor E. van Beneden that the
subneural gland in the Ascidian, and the pituitary gland in the vertebrate embryo have a
renal function, and may be considered as kidneys specially developed for the elimination
of effete matters from the blood circulating in the neighbourhood of the central nervous
system.

REPORT ON THE TUNICATA. 11

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REPORT ON THE TUNICATA. 13

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REPORT ON THE TUNICATA. 15

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REPORT ON THE TUNICATA 17

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REPORT ON THE TUNICATA. 19

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

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i;i:poi:t on Tin-: tunicata. 21

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REPORT ON THE TUNICATA. 23

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

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REPORT <>N THE TUNICATA. 2")

ANATOMY.

This section is intended merely as a short account of what is known of the anatomy
of the group, without entering into much histological detail. It is considered useful to
insert this upon two accounts, firstly, as a means of giving and explaining a complete
system of the nomenclature of parts in the group, a matter which has always been
involved in considerable confusion ; and secondly, as a basis from which to start in the
consideration of the structure of the new genera and species, so that their peculiarities
may be more readily noticed and appreciated.

The minute anatomy of certain special forms (e.g., Culeolus murrayi, see page 91)
will be found in their proper places in the systematic part of the memoir.

Classification.
The following is the scheme of classification of the Tunicata which I have adopted : —

Class— TUNICATA.

Order I. Ascidiacea.

Sub-order I. Ascidice Simplices.
Family 1. Molgulidse.
,, 2. Cynthiidae.
,, 3. Ascidiidse.
,, 4. Clavelinida;.

Sub-order II. Ascidice Com/posita.

Family 1. Botryllidse.
,, 2. Didemnidaj.
„ 3. Distomidae.
,, 4. Polyclinida3.
,, 5. Diplosomidse.

Sub-order III. Asctdiw Salj>ifor»ics.
Family Pyrosomidse.

Order II. Thaliacea.

Family 1. Doliolida-.

,, 2. Salpida-.

Order III. Lakvacea.

Familj Appendiculariidae.

(zool. aiALL. Exr.— pakt XVII. — 1882.) B 1

26 THE VOYAGE OF 11. M.S. CHALLENGER.

The Position.

Before describing any part of the anatomy of an Ascidian, it is necessary to state the
position in which one considers its body placed, and to define such terms as anterior,
posterior, dorsal, and ventral ; as these have been used by some writers to denote
entirely different regions of the body.

Savigny1 placed his specimens, when describing them, in the natural position in
which most species are found, namely, with the apertures (or the branchial aperture when
they are far apart) superior, and the base of attachment inferior. He called the edge on
which the atrial aperture is placed the anterior region, and the opposite side, that next
the endostyle, posterior. Consequently, in all typical Simple Ascidians {e.g., Ascidia
mentula), according to Savigny's nomenclature of regions, the stomach and intestine
would lie on the right side of the branchial sac.

Alder (1863),2 Alder and Hancock (1870), and afterwards Hancock alone (1870),3
employed a modification of Savigny's method. Their right and left sides were the same
as Savigny's, but they designated the region of the branchial aperture anterior, and the
base of attachment posterior. The two edges (anterior and posterior of Savigny) they
called dorsal and ventral. This was a distinct improvement, but the two last terms were
misapplied, the atrial edge being considered ventral, and the endostyle dorsal.

Milne-Edwards,4 like Savigny, placed the body upright, and called the branchial end
superior, and the place of attachment inferior. He differed from Savigny, however,
in considering the endostyle as anterior, and the atrial region as posterior, the result being
that his right and left sides are not synonymous with those of Savigny.

Kupffer's 5 terms are partly those of Milne-Edwards. He calls the region of the bran-
chial aperture either superior or anterior, and the base of attachment inferior or posterior.
The edges, however, he designates as dorsal and ventral, applying these terms not as Alder
and Hancock did, but correctly — the atrium being dorsal, and the endostyle ventral.
The right and left sides thus come to be the same as those of Milne-Edwards. Heller's *
system is much the same ; he places the animal upright, and calls the branchial aperture
anterior, and the endostyle ventral. R. Hertwig 7 also considers the branchial aperture as
anterior or oral, and the base of attachment as posterior or aboral, whde the dorsal side is
indicated by the nerve ganglion, and the ventral by the endostyle.

Lacaze-Duthiers 8 adopts an extraordinary system of nomenclature. He places the

1 Mem. aiir les anim. sans Vert., part ii. fasc. 1.

2 Observ. on Brit. Tun., Ann. Mag. Nat. Hist., ser. iii., vol. xi. p. 152.

3 On the larval state of Molgula, &c, Ann. Mag. Nat. Hist., ser. iv., vol. vi. p. 353.

4 Observ. sur les Asc. Comp., &c, Mdm. de VAcad. de Paris, vol. xviii. p. 217.

5 Jahresberichte der Kommission zur Untersuchung der deutschen Meer in Kiel. Berlin, 1874.
r' Untersuch. ii. d. Tun. des adriat. Meeres, Denhsckr. /.. Akad. Wissensck., Bd. xxxiv.

7 Beitrage zur Kenntniss des Baues der Ascidien, Jen. Zeitschr., vol. viii. p. 74.

8 Asc. Simp, des cotes de France, Arch Zool. expe'r. t. iii.

REPORT ON THE TUNICATA.

27

animal in the reverse position to that employed by most authors, that is, he has the base
of attachment upwards, and the branchial aperture hanging down. These are his superior
and inferior regions ; then the endostyle is placed forwards and called anterior, while the
opposite edge — the atrial part — is posterior. The result is that the stomach lies on what
Lacaze-Duthiers considers the right side of the branchial sac — the same arrangement as
was obtained by the systems of Savigny and Hancock, although the last mentioned
authors placed the animal so that the branchial aperture should be superior (see diagrams
in Lacaze-Duthiers' memoir).

Julin,1 and apparently Traustedt2 also, employ the same nomenclature as Heller, and
this is the system adopted in the present work. If the animal be placed with the endostyle
downwards, and the branchial aperture pointing away from the observer, then the two sides
correspond with his right and left hands. The region of the branchial aperture (fig. 1, Br.)

Fig. 1. — Diagram showing the position of an Ascidian, viewed from the left side.

A., anterior end ; P., posterior end ; D., dorsal edge ; I'., ventral edge ; Br., branchial aperture ; At, atrial aperture ; br.s., branchial
sac ; en., endostyle ; <e.a., oesophageal aperture ; St., stomach ; i., intestine ; a., anus ; n.g., nerve ganglion.

is thus anterior, and the opposite end, usually the place of attachment, is posterior ; the
lower surface, along which the endostyle {en.) runs, is ventral, and the opposite edge, on
some part of which the atrial aperture generally opens, is dorsal.

According to this system, the stomach (st.) and intestine lie (in most of the genera
and species of Simple Ascidians, e.g., Ascidia mentula) upon the left side of the branchial
sac (fig. 1) and this side corresponds to the left side of Milne-Edwards, Kupffer, Heller,
Hertwio-, Traustedt, and Julin, but to the right side of Savigny, Alder, Hancock, Lacaze-
Duthiers, &c.

1 Recherches sur rOrganisation ties Ascidies Simples, Arrh. ' U . vol. ii. p. .r>9.

5 Oversi^t over de fra Danmark, &c, Asc Simp., Vid. Maid. Nat. For. Kjfbenluimi, 1879-SO.

(ZOOL. CHALL. EXP. — PART XVII —1882.) E 5

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

The Test (Testa, Tunica Externa, Cellulose Mantle, Outer Mantle, Cartilaginous Sac).

The test or outer tunic (sometimes incorrectly called the mantle), from which the
class derives its name, is one of the most characteristic features of the group. It under-
goes many and various modifications, but it is present, and is recognisable as a " test,"
or " investing mass," in almost every member of the class. It possesses the additional
interest of being the organ in which Karl Schmidt, in 1845, made his well-known
discovery of cellulose in the animal kingdom. Since that date the principal works on
the structure of the test in the Tunicata have been those of Lowig and Kolliker (1846),
Schacht (1851), F. E. Schulze (1863), Oscar Hertwig (1872), and Semper (1875).

In a Simple Ascidian the test is a more or less thickened coat forming the outer layer
of the body wall. It varies greatly in shape according to the species, and even to a
considerable extent according to the individual, being greatly affected by surrounding
circumstances. In the so-called Social Ascidians (the family Clavelinidse) it forms in
addition the stolons or creeping roots, which connect the different individuals of the
" Society," and contain the connecting blood-vessels. In the Ascidise Compositse it is
represented by the " investing mass," the tests of the different Ascidiozooids of the colony
having fused together into a common ground mass or matrix. In Pyrosoma also there
is a colonial mass representing the united tests of the different Ascidiozooids ; while
in Salpa the test forms the outer layer of the body of each individual, as in the Ascidia?
Simplices. In the Appendiculariidae the test is represented by the structure usually
known under the name " Haus," given by its discoverer Mertens. This is only formed
at certain times, so that in these Tunicates there is sometimes no test. In certain species
of Doliolum, also, there appears to be no test.

The external surface is always more or less irregular and prone to develope knobs,
hairs, spines, and other processes. This is especially the case at the posterior end of the
fixed forms, where the test frequently pushes out long branched processes to serve
as roots for the attachment of the Ascidian to foreign bodies.

In the adult condition it is histologically an abnormal form of connective tissue, con-
sisting of protoplasts of various forms imbedded in a matrix which also varies greatly in
its characters. The test is in all cases lined by a layer of epithelial cells, the true ectoderm,
and it has its origin from these cells alone. It commences as a cuticular secretion on the
surface of the ectoderm, and afterwards attains its cellular condition by the migration
into it of protoplasts formed by proliferation from the ectoderm. These immigrated cells
then increase the thickness of the test greatly by forming deposits of cuticular matter
around themselves, thus building up the matrix of the adult test. The protoplasts may also
develop large vacuoles in their interior, which sometimes increase to such an extent as to
form what may be called a bladder-cell — a large oval or globular space in the matrix lined

REPORT ON THE TUNICATA.

29

by a delicate layer of protoplasm, and having a nucleus at one side, the whole of the
interior of the cell being a large vacuole. These are found typically developed among
the Ascidiidae (fig. 2, c, and PI. XXX. fig. 3, hi.). Other protoplasts secrete in their
interior pigment granules, generally of a dark-brown colour, and this process may be
carried to such an extent as to almost entirely obliterate the protoplasm of the cell
(fig. 2 (J., and PI. XXIX. fig. 3, p.c). Others, which remain in a less modified condi-
tion, are found scattered through the matrix in varying quantities and sizes. They may
be fusiform, rounded, stellate, or irregularly branched.

The matrix is usually clear and homogeneous, with a gelatinous or cartilaginous
consistency. Frequently, however, it becomes fibrillated in parts, and in some cases,
especially amongst the Cynthiidae, is modified into a fibrous structure, very complicated
in the arrangement of its layers, and occasionally continued into simple or branched
spine-like projections from the outer surface. In other cases some parts of the test may
undergo a sort of cornification, so as to change their appearance and consistency.

&&£&># ■■( 2 ■'-■■-■ ■

Fig. 2. — Transverse section through the test of Ascidia, showing the matrix in which lie large bladder cells (c) scattered in the inner
layers, and smaller bladder cells (a) near the surface (the left side of the figure), blood-vessels (6) with terminal knobs, and pigment
cells (d) — magnified about 40 times.

Usually, especially when it is thick, the test is penetrated by a number of blood-
vessels, which are continued out from the body wall into the test, pushing a process of
the ectoderm before them. In the adult they enter as two large trunks placed close
together, usually near the posterior end of the ventral edge, and these two main stems
almost invariably give off corresponding branches which run together, ramifying chiefly
in the outer layers of the test (PI. XXIX., fig. 3), where they end in terminal bulbs,
usually by two twigs opening into one bulb, thus allowing the two vessels to communicate.

Spicules have been described as occurring in the tests of various Tunicata. These are
probably in most cases post-mortem deposits, but in some species of Salpa siliceous
spicules appear to be normally present, while in certain of the Ascidise Composites, large
quantities of calcareous deposits are formed in the investing mass, and are in some eases
especially developed, as Giard has shown, in autumn, as a protection during the hiberna-
tion of the colony.

30 THE VOYAGE OF IOl.S. CHALLENGES.

The Mantle (The Second, Inner, or Muscular Tunic, Muscular Sac).

The second layer covering a Tunicate is the muscular and connective tissue part of
the body wall, and lies immediately inside the ectoderm or epidermis. It varies greatly
in its characters in different groups, and is to a certain extent a reliable, distinguishing
feature, especially for families and genera. It is formed of connective tissue, uniting and
enclosing bundles of muscular fibres, nerves, and blood-vessels. In some cases numbers
of the connective tissue corpuscles become pigmented, so as to give a coloured or
variegated appearance to the mantle.

In the living animal the mantle is in direct union with the ectoderm lying over it
(fig. 9, page 40), so that there is no space between the mantle and the test, but in
specimens preserved in alcohol the mantle contracts away from the test and leaves a
large cavity between, the only points of union being the sides of the branchial and
atrial siphons, and the place near the posterior end of the body where the large blood-
vessels pass across from the mantle to the test. This separation takes place much
more readily in some species than in others, while in some (Pelonaia corrugata, Poly-
carpa viridis, &c.) it apparently never occurs.

The muscular fibres of the mantle are in all cases unstriped. They are either fusiform,
or very long filiform fibres, usually more or less united together into bundles. Round
the two siphons they are arranged so as to form strong sphincters, sometimes of consider-
able size (fig. 3, sph. page 32).

In the Molgulidge the mantle is usually thin and membranous, and the muscular
bundles have a most characteristic appearance. They are united into short fusiform
packets, which present a striking resemblance to the typical form of a muscle in the
higher animals ; each having a broad central portion or belly, and two long tapering
tendon-like extremities. Another characteristic feature of the mantle in the Molgulidfe
is the arrangement of a large number of the bundles in lines radiating from the lower
edges of the sphincters so as to form a stellate figure round the base of each siphon.

In the Cynthiidae the mantle attains its greatest thickness, and in some cases the
muscular system is developed to an enormous extent. The sphincters are always strong,
and the musculature is usually equally developed in the whole mantle, except in some
cases in the region over the intestine. The bundles are, as a rule, placed regularly and
parallel, forming longitudinal and circular coats. In most typical Cyntkiidaa there is
an internal circular covered by an external longitudinal coat, and in some {e.g., Poly-
carpa varians and Styela canopus) a third internal longitudinal layer is added. In some
Bolteninse the muscular system, though arranged upon the same plan, is so reduced in
amount that continuous coats are not formed, and the longitudinal and circular bundles
form a network with large rectangular meshes.

REPORT ON THE TUNICATA. 31

In the Ascidiidae tlie musculature is much more feebly developed. In typical forms
(such as Ascidia virginea, 0. F. Muller) the muscular fibres are almost entirely confined to
the right side of the mantle — the part lying over the branchial sac, — while the left half, over
the intestine, is thin and membranous. The bundles run in all directions, branch and
anastomose so as to form an irregular network of fibres, meeting at all angles. In the
genus Ciona the arrangement is more regular. Delicate bundles run circularly, and form
a thin non-continuous coat, while much stronger bundles run longitudinally, and are
united together into twelve to fourteen strong parallel bands. In Chelyosoma the
muscular fibres are united into bundles placed between the edges of the horny plates into
which the upper part of the test is modified.

In the Clavelinidse the mantle is thin and the muscular system extremely feeble.
The bundles are delicate, and placed far apart, and they run chiefly longitudinally.

In the Ascidise Compositse also, the mantle is thin, and the musculature delicate.

In Pyrosoma the mantle is delicate and the muscle bands are confined to the
neighbourhood of the branchial and atrial siphons.

In Doliolum the muscular fibres are arranged in eight or nine distinct bundles,
which form complete hoops encircling the body, and by their contraction expel the water
in the branchial and atrial cavities through the terminal apertures ; thus propelling the
animal through the sea.

In Salpa the mantle is thin and tough, and the musculature is developed in the
form of a number of strong transverse bands, which sometimes branch and unite, and
sometimes remain distinct, but do not form complete hoops as in Doliolum. Their
arrangement is most definite and characteristic. There are also sphincters round the
two terminal apertures.

In the Appendiculariidse the only muscles known are those of the caudal appendage,
where there are two large bundles of striped muscular fibres placed at the sides of the
urochord.

Branchial Sac (Pharyngeal Sac, Branchia).

The branchial sac is probably the most important and characteristic organ of the class.
It is a modification of the pharynx or first part of the alimentary canal, and differs widely
in the different groups, thus affording valuable diagnostic characters. It is usually of
considerable size, and in most cases is almost as large as the mantle cavity, while in a
few (e.g., Ascidia mammilla ,ta), it is longer and has the posterior end folded forwards
upon the left side of the body. It communicates with the exterior by the branchial
aperture or mouth, which is placed anteriorly, and is either circular (Clavdina) or sur-
rounded by a definite number of more or less distinct lobes, varying from three (Chdeolus)
up to twelve or fourteen (Abyssascidia). The test is prolonged inwards at the edge of the

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

mouth., and sends down a delicate funnel-shaped prolongation, lining the interior of the
mantle tube (fig. 3, t'.) ; consequently the branchial siphon is formed of a tubular
process of the mantle containing the sphincter muscle (fig. 3, sph.), and both lined and
covered by a layer of test substance.

The posterior delicate edge of the lining prolongation from the test, ends against the
outer side of a ring-like pad which bounds the lower or posterior end of the branchial
siphon. This ring bears a circlet of tentacles (fig. 3, tn.) on its lower surface, and varies
greatly in its size in different forms. In some (Microcosmus) it is produced into lobes,
forming a partial diaphragm at the entrance to the branchial sac. The circlet of tentacles
is followed by a plain area, the prsebranchial zone, which is bounded posteriorly by a pair
of closely -placed parallel ciliated ridges, the peripharyngeal bands (fig. 3, p.p.). Then
comes the wall of the branchial sac proper. This is formed by the union of two membranes
■ — an inner, the wall of the pharynx, and lined by endoderm ; and an outer, the inner

Fig. 3. — Longitudinal section through the Branchial Siphon.
br. si., branchial siphon ; t., test ; t., prolongation of the test lining siphon ; sph., sphincter muscle ; In., tentacle ; ;., pnebranchial

zone ; p.p., peripharyngeal bands.

wall of a pair of sacs (the atria) formed primitively of involutions of the ectoderm.
The two membranes come into contact, coalesce, and then become absorbed at certain
points, so as to leave apertures of communication between the interior of the branchial
sac and the surrounding atrial sacs or peribronchial cavity. These apertures, which
are in the form of narrow slits known as stigmata, are separated by tubes, the walls
of which are formed by the two membranes, and the blood which flows in these vessels
is thus brought into close relation with the salt water in the branchial sac, the stigmata,
and the peribronchial cavity. The stigmata and vessels vary greatly in their size and
arrangement, and thus the structure of the branchial sac gives a number of important
characteristics for distinguishing genera and species.

There are three chief systems of vessels present in most branchial sacs. First, the
transverse vessels which run round the sac horizontally like parallels of latitude on a globe,
and separate the different rows of stigmata (fig. 4, tr.). These transverse vessels are most
constant, and only differ in calibre. In some sacs they are all of one size, while in

REPORT ON THE TUNICATA.

33

others different sizes alternate. The second set of vessels, the fine longitudinal or
interstigmatic, are on the same plane as the transverse vessels, but run longitudinally,
separating the different stigmata in a row, and serving as a means of communication
between the transverse vessels (figs. 4 and 5, l.v.). These interstigmatic vessels are some-

FlQ. 4. — A Single Mesh of the Branchial Sac of Ascidia, seen from the inside.
tr., transverse vessel ; i.l., internal longitudinal bar ; l.v., fine longitudinal vessel ; p., papilla ; jf., smaller intermediate papilla :

c.d., connecting duct.

times very irregular. The third set of vessels, the internal longitudinal (figs. 4 and
5, i.l), occupies a plane internal to the first and second, and consists of a series of stout
bars running from the anterior to the posterior end of the branchial sac at right angles
to the transverse vessels and communicating with them by short wide connecting ducts

l.v.

Fio. 5.— Diagrammatic horizontal section through a Mesh of the Branchial Sac of Ascidia, showing the interior of the transverse

vessel, connecting duct, and papilla at the right hand end.
tr., transverse vessel ; l.v., fine longitudinal vessel ; i.l., internal longitudinal bar ; p., papilla ; c.d., connecting duct ;

h.m., horizontal membrane.

(figs. 4 and 5, c.d.) placed at the points of intersection. These strong bars are a prominent
feature in the branchial sac viewed from the interior, and, along with the transverse
vessels, form the boundaries of the rectangular meshes into which the inner surface
of the branchial sac is divided.

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

In the Molgulidse and Cynthiidae the whole wall of the branchial sac is thrown into
a series of longitudinal folds running from the prsebranchial zone to the neighbourhood
of the oesophageal aperture. These folds project into the interior of the sac, and are
directed towards the dorsal lamina (fig. 6, I. -IV. hr.f.). They vary greatly in size and
number, and in some cases are almost (Styela grossularia, &c.) or quite (Evgyra) rudi-
mentary. They are especially well developed in the sub-family Cynthinse, where they
are often of very large size, and attain their greatest number on each side (12 or 13, in
Cynthia grandis, Heller).

On these longitudinal folds the internal longitudinal bars are always more closely
placed than they are in the spaces between the folds, and they become more closely placed
the nearer they get to the crest of this fold. Hence the meshes become narrower and
narrower as one passes along the side of a fold from its base to the crest. As a rule, in
the space between two folds, the rows of meshes are all of the same size.

dl.

::::.- mh.

Fig. 6.— Diagrammatic transverse section of the Branchial Sac of Styela.
I., II., III., IV. br.f., the branchial folds ; d.l, the dorsal lamina ; e»., the endostyle; mh., one of the meshes.

In the Cynthiidae the stigmata are longitudinal, and are arranged in regular rows
separated by the transverse vessels, but in the Molgulida? some of the transverse vessels
usually become irregularly placed, and branch so as to disturb the regularity of the rows
of stigmata. Then the stigmata themselves may become very irregular, as the interstig-
matic vessels are usually curved so as to form more or less complete spirals. The different
turns of the spiral are united by irregularly placed radiating vessels, thus forming stigmata
of different lengths (PI. VI. fig. 2). This arrangement of spiral interstigmatic vessels
and curved stigmata is also found in the genera Corella, Chelyosoma, and Corynascidia
among the Ascidiidse, and attains its greatest development in the genus Eugyra (PL VI.
% 8).

REPORT ON THE TUNICATA. 35

In the Ascidiidse and the Clavelinidae, there are no large folds in the branchial sac,
like those characteristic of the Cynthiidse and the Molgulidse, but in many species of the
genus Ascidia, the interstigrnatic vessels are inserted into the large transverse vessels in
an undulating, in place of a straight line (see fig. 7, and compare with fig. 5), so that the
stigmatic part of the branchial sac, the region between the large transverse vessels, is thrown
into a series of slight projections and hollows, which gives the sac a peculiar and compli-
cated appearance, especially from the exterior (PI. XXVIII. figs. 3 and 4, and PI.
XXXIII. fig. 3), where it is not obscured by the presence of the internal longitudinal bars.
This "minute plication" may be further complicated by the transverse vessels being of
different sizes, and the slighter ones being involved in the undulations, while the larger
ones are not.

In most of the Ascidiidse the internal longitudinal bars are provided on their inner
surfaces with papillae or knobdike projections (figs. 4 and 7, p.) placed at the points of
intersection with the transverse vessels, and immediately opposite the connecting ducts ;
and the broad membranes which hang from the front of the transverse vessels (figs.
5 and 7, h.m.) are attached to the side of these papillae and stretch between them like
horizontal shelves. In some species of Ciona and Ascidia one or two apertures of
communication with the peribranchial cavity, in addition to the ordinary stigmata, have
been found. They are comparatively long slits, in the posterior dorsal region, usually
one on each side of the dorsal lamina near its posterior end, and are bordered by cilia
much finer than those of the ordinary stigmata.

irn'igh

Fio. 7.-Diagrammatie horizontal section through a Mesh of the Branchial Sac of Ascidia, showing the arrangement of the fine

longitudinal vessels which causes " minute plication."
tr., transverse vessel ; l.v., fine longitudinal vessel ; U., internal longitudinal bar ; c.d., connecting duct ; p., papilla ; h.m., horizontal
membrane. " Crest " indicates the highest, and "trough" the lowest part of the undulation.

In the Clavelinidaa, the branchial sac is neither folded nor plicated, and there are no
papilke on the internal surface. In the genus Clavdina the entire system of internal
longitudinal bars is absent.

In the Ascidise Composite the branchial sac is always simple in structure, differing
little in most forms (e.g., Botryllus) from the arrangement found in Clavdina, In some
cases, however, internal longitudinal bars are found, and occasionally these bear slight
papillae (Distoma, Diazona).

(ZOOL. CHALL. EXP. — PART XVII. 1882.) K 6

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

Ill Pyrosoma the sac is formed by a series of transverse interstigmatic vessels, and of
internal longitudinal bars intersecting at right angles.

In Doliolum the stigmata may either be confined to the posterior region of the sac, as
in Doliolum miilleri, or may extend forward, as in Doliolum denticulatum.

In Salpa the branchial sac is greatly modified and reduced to a branchial " band,"
which represents the dorsal lamina. The systems of vessels uniting this dorsal band to
the endostyle are entirely absent, so that each half of the sac is converted into a single
large stigma.

In the Appendiculariidaa there are only two stigmata, one on each side of the
endostyle, near the posterior end. They lead by atrial canals, which represent the
right and left sides of the peribranchial cavity, to the exterior. The endoderm cells lining
the branchial sac are ciliated, and larger cilia are present along tracts corresponding to the
peripharyngeal bands and the dorsal lamina, and around the edges of the two stigmata.

The Peripharyngeal Bands (Pericoronal Ridges, Ciliated Arcs).

The position of the peripharyngeal bands at the anterior end of the branchial sac has
already been pointed out. They lie at the base of the branchial siphon, and the anterior
band, or, as Julin calls it, the internal lip of the groove, forms a complete ring, bounding
the prasbranchial zone posteriorly. The posterior band or external lip, on the contrary,
is complete only at the sides. At the ventral end its right and left halves turn pos-
teriorly, and become directly continuous with the marginal ridges of the endostyle ;
while dorsally they are continued into the anterior end of the dorsal lamina.

The peripharyngeal bands are formed of ridges of connective tissue continuous with
that of the mantle, and covered on their free surfaces with epithelium, which changes
gradually from low columnar in the groove to cubical and then squamous on the outer
slopes, where the ridges become continuous with the prasbranchial zone on the one
hand, and with the inner surface of the branchial sac, on the other. The cells covering
the floor of the groove, and those along the most prominent parts of the ridges, bear
very short cilia, while the anterior and posterior slopes of the ridges and the sides of
the groove are not ciliated.

Tlie Endostyle (Hypobranchial Groove).

This organ forms the ventral edge of the branchial sac, and extends from the
peripharyngeal bands anteriorly to the posterior end of the sac. It is a groove bounded
by parallel lips, often of considerable height, and jirojecting into the cavity of the
branchial sac (fig. 8). The groove is lined by a modification of the epithelium of the
interior of the branchial sac, and is in some parts cubical, and in others columnar and
ciliated.

REPORT ON THE TUNICATA.

37

Fiji's1 investigations have established that the endostyle is an organ for the secretion
of mucus, which is carried upwards to the anterior end of the sac by the action of the

It reaches the dorsal lamina, where, along with

Ions; cilia on the floor of the groove

O O

U.S.

Flo. 8. — Transverse section of the Endostyle of Mulgala gigantea.
br.s.e., epithelium lining branchial sic; hr.s.e'., epithelium on outer side of branchial sac; mt.e., epithelium lining mantle ; ec., ecto-
derm ; mi., mantle ; br.s., wall of branchial sac ; En.L, lip of endostyle groove ; ep., 1st epithelial pad on inner lip of endostyle ; «//.,
'2nd epithelial pad ; ep".,3rtl epithelial pad ; m., transverse section of inner bundles of muscular fibres ; mi, transverse section of outer
bundles of muscular fibres ; v.v., great ventral vessel ; U.S., small blood sinuses; p.br., peribronchial chamber.

entangled food-particles, it forms a long string, extending down to the oesophagus, by being
carried round the peripharyngeal groove, lying between the two peripharyngeal bands.

The endostyle is remarkably similar in all the Tunicate, and very rarely furnishes
characters which can be made use of in classification.

1 Ueber die Schleimdruse oder ilen Endostyl Jcr Tunicaten. Morphol. Jahrbuch., BA i.. p. 2-2:i. 1874.

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

TJtc Dorsal Lamina (Oral Band, Ventral Plait, Epibranchial Fold, Languets).

This structure occupies the region of the branchial sac directly opposite to the
cndostyle, and marks the dorsal edge.

In the majority of Simple Ascidians it is present in the form of a membrane of
varying breadth, according to the species, which commences anteriorly by the union oi
two pads which converge from the dorsal ends of the posterior peripharyngeal band, and
are separated by a groove, called by Julin the " epibranchial groove." This groove is also
of varying length, according to the species. In some (e.g., Corella parallelogra/mrna) it
is comparatively short, while in others (e.g., Ascidia venosa) it is of considerable length.
Although it frequently approaches close to the two halves of the peripharyngeal groove,
it appears to be always completely shut off from both by the union of the two sides of
the posterior peripharyngeal band. It is only this first or anterior portion of the dorsal
lamina which is united to the mantle ; the rest of it is free, the branchial sac being in
this region separated from the mantle by the dorsal part of the peribronchial cavity. The
epibranchial groove is lined in its entire extent with low columnar ciliated epithelium.
Behind the epibranchial groove the dorsal lamina usually widens gradually as it approaches
the oesophageal aperture, and then narrows suddenly, and terminates in a low ridge lead-
ing round the posterior end of the sac to join the extremity of the endostyle.

The dorsal lamina has, especially in its posterior broader part, the free edge somewhat
bent round, usually to the right but sometimes to the left side (fig. 9, p. 40), so as to
form a semi-canal leading down to the oesophageal aperture, and it is along this groove
that the string of food- particles agglutinated with mucus passes on its way to the
oesophagus. The left (convex) side1 of the lamina is in many species marked by a series
of more or less distinct transverse ridges or ribs, usually corresponding to the transverse
vessels and the horizontal membranes of the branchial sac, and crossing from the base to
the free edge, where they frequently terminate in projecting teeth or knobs (PI. XXXI.
fig. 7).

In different species the dorsal lamina differs considerably in its breadth and the
presence and amount of development of ribs and teeth— the length depends upon the
position of the oesophageal aperture.

In several genera of the Ascidiidse (dona, Corella, Abyssascidia, Chelyosoma, and
Corynascidia) the dorsal amina is represented by a single, or in some cases a double,
series of triangular flaps or tapering finger-like processes named languets (PI. XXV.
fig. 7, PI. XXVI. fig. 7, and PI. XXXIV. fig. 9). These are also found in the
Clavelinida3 and in some of the Cynthiidae (e.g., Cynthia and rarely Styela). In some
cases the languets are united together at their bases by a narrow membrane, so as

1 Sometimes Loth sides are ribbed transversely.

REPORT ON THE TUNICATA. 39

to resemble the ordinary dorsal lamina, with greatly exaggerated marginal projections.
In other cases there is no membrane, and the languets are quite disconnected.

In Compound Ascidians and in Pyrosoma, languets are present, forming a series along
the dorsal edge of the sac, as in Ciona ; while in Salpa there is a single very large languet
near the anterior end in the dorsal region. Behind this there is a membranous band (tin-
"gill") representing the remainder of the dorsal lamina, and extending posteriorly and
ventrally to join the posterior end of the endostyle, and thus separate the branchial sac
from the cloaca.

The Peribranchial Cavity (The Respiratory Chamber, the Atrium, the Cloaca).

The peribranchial cavity or atrium is the space surrounding the branchial sac and
communicating with the exterior by the atrial aperture, which is usually placed on the
dorsal surface not far from the anterior end, but may move backwards so as to He at a
considerable distance from the branchial aperture, or even at the posterior end of the
body, as in Pyrosoma, Salpa, Doliolum, Botryllus, Culeolus, &c. This atrial or exhalent
aperture terminates a short tubular process of the mantle, just as in the case of the
1 tranchial aperture ; and this atrial siphon is also provided with a sphincter muscle, a
lining prolongation from the test, and sometimes a partial diaphragm at its lower end,
but there is no tentacular circlet.

The peribranchial cavity is formed in the embryo by two lateral epiblastic involutions,
which unite dorsally, and surround the branchial sac, except along its ventral edge,
where the two lateral halves of the peribranchial cavity are separated by the union
of the endostyle to the mantle (fig. 9, p. 40). The epithelium which lines the two atrial
involutions forms in the adult Ascidian the " lining membrane " of the atrium, or the
" third tunic " of Milne-Edwards, and is divided into the parietal layer lining the mantle
(fig. 9 mt.e.) and forming the outer walls of the cavity, and the visceral layer covering
the branchial sac and constituting the inner wall. The cavity is crossed by blood-vessels
connecting the branchial sac with the sinuses in the mantle (fig. 9 con.). Besides these,
called "connectives" by Hancock, the branchial sac is united to the mantle by the
oesophagus, along the entire length of the endostyle, round the anterior end at the
peripharyngeal bands, and along the first portion of the dorsal lamina.

The peribranchial cavity is in free communication with the interior of the branchial
sac through the stigmata, and is traversed by the water in its course to the atrial
aperture. The anus and the genital ducts open into the peribranchial cavity in the
dorsal median region, often called the cloaca. Consecpiently the epithelium of the peri-
branchial cavity (the "lining membrane") is continuous with the endoderm of tin-
branchial sac at the stigmata and of the rectum at the anus, and also with the epithelium
lining the genital ducts.

40

THE VOYAGE OF H.M.S. CHA.LLENGER.

In the AppendiculariicUe the peribranehial cavity is represented by two "atrial canals,"
which connect the two stigmata of the branchial sac with the exterior. They lie on the
ventral side of the sac at the sides of the endostyle, and the apertures are near the middle
of the ventral surface close to the anus. A similar condition of parts is found at a
comparatively late stage of development in Simple Ascidians, and the single peribranehial
cavity of the adult is the result of the fusion of the two atria, into one of which the

■g.«L

l].s.

... ty.

v. v. ' ni.T).

Fiq. 9. — Diagrammatic transverse section through the middle of the body of Ascidin.

t.,test; ec. , ectoderm ; >«., mantle; m.b., muscle-bands in mantle; U.S., blood sinus in mantle ; w.v., great ventral vessel ; mt.e., epithelium
lining the peribranehial cavity ; p.br., peribranehial cavity; cl., cloaca; br.s., cavity of branchial sac ; l.v., longitudinal vessel of bran-
chial sac; sg., stigma ; ere., endostyle ; br.s.e., epithelium lining branchial sac ; d.l., dorsal lamina; con., connective between branchial
sac and mantle; L, section of intestine ; ty., typhlosole ; ov., ovary; r.o., renal organ ; r., section of rectum; g.d., section of genital
ducts.

anus has come to open. The common aperture finally moves to the dorsal surface of
the body ; consequently the dorsal atrial aperture of the Ascidian represents the
three ventral apertures of Appendicularia.

TtKrORT ON THE TUN1CATA. 11

Tentacles (Branchial Filaments).

The tentacles have been already referred to, and (heir position at the posterior end
of the branchial siphon described (fig. 3, tn., p. 32). They are hollow processes, not
of the involuted test but of the wall of the alimentary canal, and of the mantle, as these
two are in contact in that region, the peribranchial space not extending so far forward.
The epithelium covering the tentacles is continuous with that of the praabranchial zone,
while the connective tissue underneath, usually containing muscle bands, is in connection
with that of the mantle. Blood sinuses from the latter are also prolonged up the centri
of the tentacles, so that the blood circulates in their interior.

They vary greatly in size and shape in different genera and species, and very
frecpuently they are of different sizes, arranged symmetrically. In a few cases (<■</.,
Culeolus wyville-thomsoni and Molgula pedunculate) one of the tentacles is very much
larger than any of the others.

In the Molgulidae the tentacles are always compound, and are usually much branched,
in some of the larger species (e.g., Molgula gigantea) forming huge complicated
arborescent masses. Their number in the Molgulidaa is never very great. A not
uncommon arrangement is for seven or eight large tentacles to alternate with the same
number of smaller ones.

In the Cynthiidae we find a great variety of tentacles. Two of the sub-families, the
Bolteninae and the Cynthinae, have compound tentacles very similar to those of the
Molgulidae, but usually more numerous, while the third sub-family, the Styelinae, has
simple unbranched tentacles like those of the Ascidiidae, but frequently wider at the base,
and having a more inflated appearance.

In both the Ascidiidae and the Clavelinidae they are also simple, and present the form
of long tapering processes, usually distinctly triangular in cross section, and placed with
a flat surface anteriorly, and a ridge posteriorly. Among the Ascidiidae we frequently meet
with complex arrangements. The tentacles may be of different sizes, two, three, or
more orders being placed alternately.

In the Ascidiae Compositae the tentacles are invariably simple, and few in number.
They are usually all of the same length, although in some cases (e.g., Botryllus, where
there are four larger alternating with four smaller) two orders occur.

In the Appendiculariidae, the Pyrosomidte, and the Thaliacea the tentacles seem to be
entirely absent.

Nervous System.

A single large nerve ganglion is found in all Tunicata placed between the branchial

and atrial siphons, and is usually considered as indicating the dorsal surface of the

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

animal. It lies in the mantle near its inner surface, underneath the muscular la)Ters,
and above the neural gland.

It has usually an oblong form, slightly constricted in the middle, and giving off nerve
trunks from the expanded ends, one of which is directed anteriorly and the other
posteriorly.

In the Ascidias Simplices, where the branchial and atrial apertures are usually approxi-
mated, the nerve ganglion lies in the angle between them, almost invariably nearer the
branchial than the atrial aperture (the reverse is the case in Ascidia compressa and
Asctdia fusiformis), and the anteriorly and posteriorly directed nerve trunks run directly
to the neighbourhood of the apertures, and give off branches to the tentacles, the ocelli,
and the margins of the lobes.

In Appendicidaria there is a large ganglion, with three dilatations, placed in the
usual position on the dorsal side of the anterior end of the pharynx, and giving off, in
addition to nerves to the branchial aperture, a long nerve trunk, which runs back along-
side the oesophagus and past the stomach till it reaches the base of the caudal appendage.
Here it goes to the left side of the urochord, along which it runs to the extremity, giving
off nerves from ganglionic enlargements which occur at intervals. The most anterior of
these caudal ganglia is the largest. Fol states that this gangliated nerve trunk is tra-
versed by a fine canal.

The periphery of the ganglion is formed of globular or pyriform unipolar nerve cells,
while the centre is a mass of nerve fibres, with a very few small nerve cells scattered
through it. The nerve trunks arise from this central fibrous part.

Sense Organs.

In the adult Simple and Compound Ascidians the only structures which can be called
sense organs — now that the sensory nature of the so-called " olfactory tubercle " has
been disproved — are the tentacles round the base of the branchial siphon, which have
probably some sensory function, and the ocelli or pigment spots situated around the
branchial and atrial apertures. They are usually equal in number to the lobes surround-
ing the apertures, and are situated in the clefts between them. The pigment, which is
almost invariably red, is imbedded in the mantle just above the anterior edge of the
sphincter muscle, where the test is usually thin and transparent, and is supplied by
branches of the nerve trunks from the anterior end of the nerve ganglion.

In Appendicularia there is a rounded otocyst, containing a spherical otolith, attached
to the main ganglion, while Fol has described a number of fine tactile setaa situated
around the branchial aperture. In some forms of Doliohtm there is also a spherical
otocyst, containing a single otolith and supplied by a nerve from the ganglion.

REPORT OX TllK TUNTCATA.

40

In the lobes around the branchial aperture in Doliolum, in Sal pa, and probably in
other forms also, there are certain modified ectodermal cells, which appear to be nerve-
endings. They have filamentous processes which extend to the surface, and these have
probably a tactile function.

In Pyrosoma there is a visual organ formed of an outgrowth from the nerve ganglion,
covered with pigment and having a refracting body imbedded in it ; and in Salpa there
is a similar organ also placed upon the ganglion.

Tlie Neural Gland and Duct (The Hypophysial Gland, the Olfactory Gland).

Underneath the nerve ganglion, and imbedded in the innermost layer of the mantle,
lies a gland first noticed by Hancock in 1868, afterwards more fully examined by Ussow

Fir:. 10. — Diagrammatic transverse section through the dorsal region of the anterior end of a Simple Ascidian.
'..test; ec. , ectoderm ; n.g., nerve ganglion; m., muscle bands; U.S., blood sinus; gl., subneural gland; gl.d., duct of the gland:

br.s.e., epithelium lining the branchial sac ; e.g. epibranchial groove.

and Nassonoff (who first demonstrated its glandular nature), and brought prominently into
notice lately by Julin.1 According to this author the neural gland corresponds to the
pituitary gland of the vertebrate brain, and retains by means of its duct, to be presently
described, that primitive connection with the pharynx which is lost in higher forms.

In structure it is a tubular ramified gland (fig. 10 gl.) having a number of caecal
tubes lined by cubical epithelium, and surrounded by connective tissue containing a very
large number of blood sinuses. The caeca all converge towards the ventral surface of

1 Julin, Arch. <le Biologie, t. ii. p. 59, 1881.

(ZOOL. CHALL. EXP. — TART XVII. — 1S82.)

i; 7

.o<3

^H

t>z>-

44

THE VOYAGE OF H.M.S. CHALLENGER.

the duct and open into it in its posterior half or three-fourths, the glandular epithelium
of the tubes being continuous with the epithelium of the duct.

A.S to the function of the neural gland, van Beneden's recent suggestion that it is a
renal organ in connection with the nervous centre seems probable, and is supported by
the cisr of Ascidia mammdlala, where the apertures of the numerous secondary ducts or
infundibula open into the peribranchial space.

The duct (figs. 10 and 11, gl.d.) is delicate, and is lined by a single hvrer of cubical
epithelium. It runs anteriorly, directly under the front part of the nerve ganglion

Tjrn

. at.iL

Fig. 11. — Diagrammatic longitudinal vertical section through the dorsal region of the anterior end of a Simple Ascidian.

hr.iK. branchial nerve ; at.n., atrial nerve ; n.g., nerve ganglion ; gl., subneural gland ; gl.d., duct of the gland ; d.t., dorsal tubercle ;

p.p., peripharyngeal band ; e.g., epibranchial groove ; d.L, dorsal lamina ; Br.s., branchial sac.

and above the anterior part of the dorsal lamina, till it terminates by a complicated
aperture best known as the olfactory or dorsal tubercle (fig. 11, d.t.), situated in the
dorsal region of the anterior end of the branchial sac.

The Dorsal Tubercle (The Anterior Tubercle, the Branchial Tubercle, the Ciliated Organ,

the Olfactory Tubercle.)

This, the aperture of the duct from the neural gland, is situated in a diverticulum
from the prsebranchial zone, the peritubercular area, formed by the bending jwsteriorly
of the right and left peripharyngeal bands before they join at the anterior end of the
dorsal lamina. Primitively, there is little doubt, it was in the form of a simple circular
opening probably with prominent edges. It is still found in this or a very slightly
modified form in Molgula pyriformis and Eugyra kerguelenensis. In most cases, how-
ever, the aperture is found in a much more complicated condition. This seems to have
resulted from a forcing backwards of the anterior part of the edge till it almost came
in contact with the posterior part, thus reducing the circular aperture to a slit curved in
the form of a semicircle, with its concavity directed forwards, and bounded by prominent
lips, usually more conspicuous than the aperture. This stage is found in Ascidia seabra.

Further complications are produced by the lips round the ends of the slit or " horns,"
as they may be called, being greatly prolonged and bent or coiled in various directions.

REPORT ON THE TUNICATA. 45

Sometimes both horns are coiled inwards towards each other, sometimes outwards, and in
other cases they curve in opposite directions. The resulting forms seem almost endless,
and although the dorsal tubercle affords in some cases characters of value in classification,
still it cannot be relied upon, and in many species (e.g., Ascklia virginea and Styda
grossularia) exhibits a considerable amount of individual variation.1

In a few cases the dorsal tubercle is still further complicated, apparently by the
development of lateral branches from the original slit as in Boltenia pachydermatina
(PI. VII. fig. 8), while in Cynthia irregularis (PI. XVI. fig. 12) the primitive
aperture has evidently become subdivided into a number of openings, each bounded by
prominent lips.

In those cases where the organ is complicated, and has a pair of closely coiled spiral
horns, the raised lips of the aperture make a considerable projection, and give the ap-
pearance of a tubercle with a curiously sculptured surface (as in Ascopera gignitfai,
PL III. fig. 5). For a long time this was considered from its appearance, its proximity to
the nerve ganglion, and its position at the entrance to the branchial sac, as a sense organ,
and was hence called the olfactory tubercle. Ussow and Julin have, however, definitely
established (l), that the tubercle is not sensory, and has no nervous connection with the
ganglion ; and (2), that it is simply the aperture by which the duct of the neural gland
communicates with the branchial sac.

The slit forming the aperture leads into a funnel-shaped cavity (fig. 11, cl.t.), the com-
mencement of the duct, and this is lined by an epithelium of columnar cells provided
with very long cilia. This is replaced by cubical non-ciliated cells on the lips of the
aperture, and that graduates into the squamous epithelium covering the surface of the
prsebranchial zone. Under the epithelium is a layer of connective tissue continuous
with that of the mantle.

The Alimentary Canal.

The first portion of the alimentary canal, consisting of the mouth and pharynx, has
already been fully described as the branchial aperture, the siphon, and the branchial sac.
The next portion, or alimentary canal proper, consisting of the oesophagus, stomach, and
intestine, commences with the oesophageal aperture, placed near the posterior extremity
of the dorsal lamina, and terminates in the anus, which opens into the dorsal pari of the
peribranchial or atrial cavity — the large space surrounding the branchial sac.

The stomach and intestine almost invariably lie at one side of the branchial sac.
usually the left, and may either be comparatively free or attached along the whole extent
to the inner surface of the mantle, and covered by the layer of squamous epithelium lining

1 See Herdman, On the Olfactory Tubercle as a Specific Character in Simple Ascidians, Proc. Roy. Phys. Sue.
Edin., vol vi. p. 254, 1881.

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

the peribranchial cavity, and forming the "lining membrane" of Hancock (the "third
tunic" of Milne-Edwards) (see fig. 9, page 40).

The typical arrangement among Simple Ascidians (e.g., Ascidia mentula) is for the
oesophagus to run posteriorly and ventrally from the branchial sac, to open into the
large fusiform, globular, or cylindrical stomach, which extends towards the ventral edge
of the mantle cavity (fig. 12). The intestine emerges from the most ventral and
anterior part of the stomach, and runs anteriorly for a short distance, and then turns
dorsally and posteriorly, so as to point towards the stomach. Before reaching that organ,
however, it bends dorsally and then anteriorly, becoming the rectum, which runs forwards
near the dorsal edge of the peribranchial cavity to terminate in the anus, usually situated
near the atrial aperture (fig. 12, a, and fig. 1, page 27).

This arrangement prevails with slight modifications throughout the genera Ascidia
and Pachychlcena. In Ciona — a simpler form — the stomach and part of the intestine
lie posteriorly to the branchial sac, and the rest of the intestine has a straighter
course than is the case in Ascidia. In the genus Corella the alimentary capal lies at
the right side of the branchial sac, and the intestine turns posteriorly on leaving the
stomach. After a very short course it bends dorsally, and after running parallel to
the stomach and oesophagus it turns anteriorly, and becomes the rectum. Consequently
the three genera — Ascidia, Ciona, and Corella — have the relations of the branchial sac and
the intestine very different. Ciona seems to be the more primitive form, from which
the other two may have been derived.1 In Ahyssascidia the arrangement is much the
same as in Corella, but the entire canal is more closely packed at the posterior end of the
body (PL XXVII. fig. 3).

In most of the Clavelinidse the arrangement resembles that found in Ciona. In the
genera Clavclina, Ectcinascidia, and Rhopalwa, the intestine is greatly prolonged pos-
teriorly to the branchial sac, so as to form a fairly distinct region of the body, named by
Savigny the abdomen. In Perophora, on the other hand, there is no distinct abdomen,
the intestine having become drawn up alongside the branchial sac on its left side.

In the Cynthiidaa there is considerable variation in the situation, length, and
disposition of the intestine. Probably the simplest condition is that found in Culeolus
among the Bolteninse. Here the atrial aperture has retained what is probably its primi-
tive position, at or near the posterior end of the body (PI. VIII. fig. 8), and conse-
quently the anus opens in that region of the peribranchial cavity, thus dispensing with
the long anteriorly running rectum so well developed in Ascidia. Consequently the
intestine, after leaving the stomach, merely turns forwards and then backwards again
towards the atrial aperture.

In the Molgulidse the stomach and intestine lie upon the left side of the branchial sac,
and form a single, transversely directed, narrow loop, the posterior segment of which is

1 See Herdman, Notes on British Tunicata, Jour. Linn. Soc, Zool., vol. xv. p. 274, 18S0.

REPORT ON THE TUNIC AT A.

47

Jir.

Fio. 12.— Diagram of a dissection of Ascklia, from the right side, to show the relations of the different "tunics" and

cavities, the course of the alimentary canal, Jcc.
Br,, branchial aperture; At., atrial aperture; I., test ; m., mantle; br.s., branchial sac; br.s?., outer surface of branchial sac; en.,
endostyle ; d.l., dorsal lamina ; p.br., peribranchial cavity; in., tentacle; cl., cloaca; as.a., CBSOpl rture; ty., typhlo-

sole in intestine ; a., anus ; n.g., nerve ganglion ; gl., neural gland ; yl.d., duct from neural gland ; <j., genital organs ; g.d., genital
duct.

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

constituted by the oesophagus, the stomach, and the first portion of the intestine, while
the second portion forms the anterior segment of the loop, lying close to and parallel
with the posterior. From the dorsal end of this second portion of the intestine a short
rectum usually runs anteriorly towards the atrial aperture. Sometimes the loop of the
intestine is so long that, after extending to the ventral edge of the body, it is turned
round anteriorly and then dorsally, so as to almost completely surround the left genital
mass (PL V. fig. 9), which lies anteriorly to the intestine.

In the Ascidise Composite the stomach and intestine always project beyond the
branchial sac, but to very different degrees in different forms. In Botryllus they are
close to the branchial sac, and there is no distinct abdomen ; while in Amaroucium and a
number of allied genera the intestine projects for a long way behind the branchial sac,
and an abdomen as long as, or longer than, the thorax is formed. Botrylloides, Didem-
num, and some other genera, show a state of affairs intermediate between these extremes.
In all these forms the oesophagus commences near or at the posterior end of the branchial
sac at the dorsal side, and after running posteriorly for a short distance opens into the
stomach. The intestine emerging from the opposite end of this organ still runs posteri-
orly for a short distance, and then turns round towards the ventral side to run anteriorly.
It afterwards crosses the oesophagus, so as to become dorsal again in its last part, which
opens as usual into the peribranchial cavity.

In Pyrosoma, the alimentary canal is placed transversely at the posterior end of the
branchial sac, but on account of the position of the atrial aperture at the opposite
extremity of the body from the branchial, the intestine bends round posteriorly so as to
describe a circle.

In the Thaliacea the digestive canal and genital glands are usually aggregated into a
small mass, the " nucleus," placed in the ventral region of the posterior end of the body.

In Appendicularia the oesophagus commences at the narrow posterior end of the
branchial sac, and leads ventrally towards the large stomach, which lies transversely and
has two lobes, a right and a left. The latter gives rise to the intestine, which turns
forwards as a short rectum and terminates in an anus placed on the exterior of the body
about the middle of the ventral surface.

In many Tunicates the wall of the intestine is raised up to form a fold, which projects
into the lumen (fig. 9, page 40, and fig. 12, ty., page 47). This "typhlosole" varies
somewhat in its development in different species, extending throughout the entire intes-
tine in ^ome (Styela tuberosa), wdiile in others it is only present in a part of it. The
connective tissue underneath the endoderm and forming the centre of the fold usually
contains large blood-vessels.

Several glandular appendages are found in connection with the alimentary canal in
the Tunicata, and are, like a number of nondescript organs in other groups of the
Invertebrata, usually referred to as the liver.

REPORT ON THE TUNICATA. 49

In the Molgulidse there is a well-developed glandular mass, usually divided into
several lobes, which, in the absence of definite information as to its function, may be
called a liver. A similar organ is found coating the stomach in many of the Cynthiidse,
and in other forms, and in some of the Ascidiiche and sonic Ascidia.' Composite there are
thickenings of the wall of the stomach, which are possibly a less developed form of the
same organ.

In many other cases, including Simple and Compound Ascidians, and also Sod/pa,
Doliolum, and Pyrosoma, there is present a system of fine tubules ramifying over the
stomach and part of the intestine. The tubules in all cases are colourless and highly
refracting, branch dichotomously, and unite into one or two larger tubes, which open into
the pyloric end of the stomach, or the first portion of the intestine.

This organ has been known since the time of Savigny, and has been considered by
some authors as a liver, by some as a system of lacteals, and by others as part of the
circulatory apparatus. In some cases (some species of Salpa) a simple network of tubules
is formed by the dichotomous branching of the main duct, the twigs anastomosing freely.
In other cases (Salpa, Pyrosoma, Ascidia) a similar network is formed, but all the twigs
terminate in pyriform enlargements or ampullae, which are scattered over the meshes and
give a characteristic appearance to the system. In other forms again (Ascidia., Clavelina,
Perophora, and various Compound Ascidians) the tubules do not anastomose, but merely
branch freely and finally end in ampullae. Chandelon (1875) examined this organ
minutely in Perophora, and found that the walls of the tubules were formed of a single
layer of cubical or low columnar cells, placed upon an apparently structureless basement
membrane. The cells are distinctly nucleated and sometimes granular, and bear short
cilia projecting into the lumen of the tubule. He also found that the terminal ampullae
frequently contain highly refracting rounded concretions.

The function of this system is still rather enigmatical. Chandelon considers that it is
neither renal nor hepatic, but that it must be considered as a digestive gland, secreting a
clear fluid which flows into the intestine, but the exact action of which is at present
unknown.

Renal Organs.

Several different organs have been recognised in the Tunicata as having a renal
function. In the Molgulidae there is a sacdike, usually sausage-shaped organ (PI. IV.
fig. 7, r.o.), lying on the inner side of the mantle on the right side of the body, posterior
to the genital mass of that side, and separated by the lining membrane from the peri-
branchial cavity. It lies alongside the pericardium in its entire extent, and undoubtedly
eliminates waste products from the blood. These are not expelled from the body, but are
stored up in the form of usually rounded or nodulated concretions which, as was first
shown by Kupffer in 1872, contain uric acid. Huxley (Manual of the Invertebrata, 1877)

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

considers that this body may be regarded as the representative of the glandular portion
of the organ of Bojanus.

In some of the Molgulidse (the genus Lithonephrya of Giard) this renal organ is
always found occupied by a single large concretion, which almost entirely fills its cavity.

In many of the Ascidiidse we find another kind of renal apparatus. A large number
of huge clear-walled spherical vesicles are aggregated together in a mass lying around the
intestine, and in the thickness of the mantle (fig. 9, r.o., p. 40), while a number of small
blood-vessels and sinuses ramify through the mass. As in the case of the Molgulidse, there
is no excretory duct, and the elimination products are stored up in the thin-walled vesicles
in the form of spherical concretions concentrically laminated, and sometimes having shells
of different tints of yellow and brown, and are usually covered by a thickish coating of a
pure chalky white. These concretions contain a considerable amount of uric acid.

Finally, as has been stated above, E. van Beneden and Julin have shown strong
grounds for the belief that the neural gland is a renal organ, especially devoted to
the nerve ganglion. If this be the case, then this gland differs totally from the other
renal organs in the Tunicata, inasmuch as it possesses a duct by which the eliminated
substances are excreted either into the branchial sac or the peribronchial cavity.

Blood- Vascular System.

The heart in the Tunicata is a simple sac or fusiform tube, from the two ends of
which vessels are given off. It is enclosed in a delicate membranous sac, the pericardium,
formed, according to Hancock, of a fold of the lining membrane of the peribronchial
cavity, to which it is attached along one side from end to end.

In all Tunicates in which the matter has been investigated, the periodic reversal of
the blood current, first noticed by Kuhl and van Hasselt in the case of Salpa has been
found. The heart, after contracting for a certain time in one direction, stops, and then
the waves of contraction begin to pass along it in the opposite direction, consecraently
the blood is propelled from the dorsal and ventral ends of the heart alternately. In
the young Ascidia virginea there are usually from 35 to 40 contractions in one direction
at a time, and this takes from 1 min. 30 sec. to 2 min., whde the pause between the two
series of contractions is usually 7 or 8 seconds in duration, and thus equals three ordinary
contractions.

The heart varies considerably in position in different forms. In the Molgulidse it is
placed on the right side, and adheres to the inner surface of the mantle immediately
anterior to the renal organ.

In the Cynthiidse, as a general rule, it lies in close relation to the stomach or the first
portion of the intestine, but in the curious Cideolus, it is situated on the right side of
the body, close to the endostyle, and attached to the inner surface of the mantle.

REPORT ON THE TUNICATA. 01

In Ascidia the heart lies upon the left side of the body, along the posterior edge of
the stomach, while in C 'to na it is also in close relation to the stomach, but runs more
antero-posteriorly than in Ascidia, on account of the changed relations of the alimentary
canal. In Corella the heart is placed comparatively far forwards, being situated upon
the anterior border of the stomach, and consequently upon the right side of the body.

In Clavelina the heart is placed in the abdomen, and runs antero-posteriorly along
the side of the stomach on its inner edge.

In the Ascidise Composite the heart varies somewhat in position in different groups,
and, according to Milne-Edwards, is always in close relation to the generative organs. In
Botryllus, where there is no abdomen developed, both heart and genitalia are situated close
to the posterior part of the branchial sac, the heart being on the left side. In Didemn urn and
some allied forms, the heart runs alongside the stomach on the right side of the abdomen,
while in Amaroucium and a number of other genera, the heart and the genital organs form
a long projection, extending far beyond the intestine, and known as the post-abdomen.

In Pyrosoma the heart is placed towards the posterior end of the ventral edge of the
branchial sac, and near the stomach.

In Salpa the heart is large, and is situated close to the visceral nucleus on its anterior
and ventral sides.

In the Appendiculariidge the heart only is known. It is a short sac placed upon the
ventral side of the stomach, between the two lobes, and having longitudinal slits in its
sides. Neither Huxley nor Fol have been able to observe blood corpuscles.

In the forms in which it has been most completely made out, the circulation is as
follows: — A large vessel arises from each end of the heart (fig. 13, h.). One of these (br.c),
after giving off a branch to the test (v.t!.), runs along the ventral edge of the branchial
sac below the endostyle (v.v.), and gives off lateral branches which open into the transverse
vessels (tr.) of the branchial sac, and thus distribute the blood to be aerated. The heart
itself is in all probability merely the modified posterior end of this great ventral vessel.
The trunk arising from the dorsal end of the heart (cs^j.) gives off first a branch to the
test (v.t.), which turns towards the corresponding branch from the ventral vessel, and the
two pass side by side through the mantle, to enter the test usually near the posterior end
of the ventral side. In the substance of the test they break up into branches, which run
alongside one another, and finally communicate in the terminal knobs (t.k.) of the ulti-
mate twigs. The dorsal trunk then gives off branches to the mantle (v.m.), and ends by
breaking up into a number of vessels for the stomach (v.st.), intestine, and reproductive
organs.

The blood circulating in the mantle, the stomach, the intestine, and the reproductive
organs is then collected by several vessels (sp.&r.) opening into a large trunk (d.v.) lying
along the dorsal edge of the branchial sac, and communicating with the dorsal ends of the
transverse vessels of the sac. Thus, as Lacaze-Duthiers has pointed out, there are three

(ZOOL. CHALL. EXP. PART XVII. 1882.) R 8

THE VOYAGE OF H.M.S. CHALLENGER.

Fig. 13. — Diagrammatic longitudinal section of Ascidia, showing the heart, the blood-vessels, the branchial sac,
the alimentary canal, &c, from the left side.

br.si., branchial siphon ; at. si., atrial siphon ; t., test ; m., mantle ; br.s., branchial sac ; p.br., peribronchial cavity ; cl., cloaca ; n.g.,
nerve ganglion ; tn., tentacle ; gl., neua'al gland ; ce.a., oesophageal aperture ; st., stomach ; £., intestine ; r., rectum ; a., anus ; ov.,
genital organs ; g.d., genital ducts ; h., heart; c.sp., cardio-splanchnic vessel ; v.t., vessel to the test; t.k., terminal knob on vessel
in test ; v.t'., vessel from the test ; v.st., vessel to the stomach, &c. ; r.m., vessel to the mantle ; v.m'., vessel from the mantle ; d.v.,
dorsal vessel ; tr., transverse vessel of branchial sac ; l.v., fine longitudinal vessel of branchial sac ; sg., stigmata of branchial sac ;
v.v., ventral vessel ; br.c, branchio-cardiac vessel ; sp.br., splanchuo-branchial vessel.

REPORT ON THE TUNICATA. 53

great systems of vessels : 1st, the branchio-cardiac, bringing (when the heart is contract-
ing from the ventral towards the dorsal end) purified blood from the branchial sac to the
heart by means of the ventral vessel ; 2nd, the cardio-splanchnic, conveying arterial
blood from the heart to the viscera, and also to the test and mantle ; and 3rd, the
splancbno-branchial system, conveying the impure blood, which has been circulating in
the viscera and the mantle, to the respiratory organ by means of the dorsal vessel of the
branchial sac. Besides these systems, there are series of anastomotic vessels, crossing
from the branchial sac to the mantle, from the mantle to the test, and from the test to the
branchial sac.

When the heart contracts from the ventral to the dorsal end it is purely systemic,
and contains almost pure arterial blood, the only admixture of venous being the stream
returning from the test (v.t'.), which, enters the branchio-cardiac vessel near its junction
with the heart. When, on the other hand, the heart contracts from the dorsal to the
ventral end, it is almost purely respiratory (not completely, as it supplies the test as well
as the branchial sac), and contains impure blood returned from the viscera, the mantle,
and the test. Hence the test receives a supply of pure blood from the heart only when
that organ is contracting ventro-dorsally.

The blood in the Tunicata consists of a clear fluid plasma, in which float corpuscles.
These are nucleated protoplasts of considerable size, and usually rounded in outline.
Many are always clear and colourless, but generally a number are pigmented. The
commonest colours are yellow, red, and brown, but white and blue have also been
noticed.

The Reproductive Organs.

The Tunicata are hermaphrodite, though certainly in some and probably in many
cases not self-fertilizing. The male and female glands are always situated together, but
the closeness of their union differs in different groups. In some forms they do not
attain maturity at the same time. In Botryllus, Appendicidaria, &c, the ova are ripe
long before the testis is fully developed.

In the Molgulidse the ovaries and testes are united into two usually ovate, hermaphrodite
genital masses, a right and a left, which are attached to the inner surface of the mantle.
The right mass is placed in the centre of the right side anteriorly to the heart, and
usually lies wdth its length placed transversely, and the genital ducts at the dorsal end.
The left organ lies in the corresponding position on the left side and in front of the
intestinal loop, except where the loop is so long as to make a secondary bend anteriorly,
in which case the genital mass is bounded both in front and behind by the intestine.1
In the genus Eugyra only this left genital gland is present.

In the Cynthiidaa we meet with a number of different arrangements. In Otdeolus there

i As in Molgula ccepiformis, see Sorby and Herdman, Journ. Linn. Sot, Zool., vol. xvi. p. 527.

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

arc a series of quadrate genital masses (PI. VIII. fig. 10) along each side of the body
projecting into the peribranchial cavity. Each mass (PI. VIII. fig. 11) is composed
of a central testis, around which is the ovary. The testes are all connected by a con-
spicuous winding vas deferens, behind which is a wider oviduct.

In Cynthia the testes and ovaria are usually united into one or more ramified or
lobed masses, which are placed between the inner surface of the mantle and the lining
membrane, which is pierced by the ducts opening into the peribranchial cavity.

In Pelonaia there are two elongated genital masses, one upon each side and attached
to the mantle. Each consists of a tubular ovary, bent in a wide loop, with the oviduct
opening in front, and of a series of testicular vesicles arranged along the sides at right
angles to the ovary, and having ducts which pass across it to join a central vas deferens
terminating anteriorly along with the oviduct.

In Stijela various arrangements are found ; — usually one or two long sausage dike
masses are formed, each of which is composed of a number of small ovaria and testes,
while in the nearly allied Polycarpa all the small glands are distinct, so that there are a
very large number of small ovaria and testes projecting from the inner surface of the
mantle, and each opening separately into the peribranchial cavity. In some species a
number of these small testes are arranged around each of the ovaries, and their ducts
join to form a common vas deferens opening beside the short oviduct. In several genera
of the Cynthiidse there are projections from the inner surface of the mantle, sometimes
pedunculated and rather like the genital glands, which have been described under the
name of " endocarps." They are formed chiefly of the connective tissue of the mantle,
and contain a large number of blood sinuses. Kupffer has noticed that they are
especially developed in species with a powerful musculature in the mantle, and hence he
considers that they are reservoirs into which the blood in the mantle sinuses may be
injected when the body is forcibly contracted. Possibly, as suggested by Hancock, they
serve merely as pads to keep the branchial sac and the genital glands apart.

In Ascidia the ovary and testis are single racemose glands lying in the fold of the
intestine on the left side of the body (fig. 9, p. 40, and fig. 13, ov., p. 52), and some-
times extending partly over the wall of the intestine and stomach. The ovary is usually
a branched organ, the different branches uniting at a point near the centre of the
intestinal loop where the oviduct commences. This duct runs along the posterior border
of the intestine, and the dorsal edge of the rectum, to open into the peribranchial cavity
near the anus. The testis is formed of a large number of delicate white tubules which
branch dichotomously over the ovary, the stomach, and the intestine, and end in small
pyriform or elongated enlargements. A vas deferens, commencing like the oviduct at
the point of union of the tubules, runs alongside the oviduct during its entire course, and
terminates beside it in the peribranchial cavity.

In Clavelina the genital glands he in the abdomen, on the left side of the intestine,

IIKPUKT ON Till: TUXK'ATA. 55

and the ducts lead up alongside the rectum just as in Ascidia. The ovary shows a mass
of ova of different sizes, while the testis has its ducta much branched dichotomously and
ending in elongated vesicles united in pairs.

In the Ascidiae Composite the position of the genital organs varies, as Mdne-
Edwards showed, according to the position of the heart. In Botryllus they are placed
alongside the branchial sac. In Didemnvm and allied forms tiny are, as in Clavelina,
in the abdomen on the side of the intestine ; and finally, in Amaroucium and a number
of other genera, the genital glands, along with the heart, constitute the long post-abdomen
which projects behind the loop of the intestine.

In Pyrosoma each ascidiozooid of the colony has a rosette-shaped testis and a female
gland or " ovisac," containing a single ovum, and communicating with the atrial cavity
by a short oviduct. In Doliolum there is a long tubular testis placed ventrally and
opening into the atrial cavity. The ovary is small and lies at the posterior end of the
testis. In Salpa only the forms united in chains develop genital organs — the solitary
forms reproducing by gemmation. As in Pyrosoma a single ovum is formed in an
ovisac united to the atrial cavity by a short oviduct. The testis is a large branched
organ forming part of the visceral nucleus. Brooks considers that the Salpce united in
chains are the males produced by gemmation from the solitary form, which is the true
female, and which has deposited an ovum in the body of each male, where it matures,
becomes impregnated, and develops into a female solitary Salpa.

In the Appendiculariidse the genital glands lie in the posterior part of the body, behind
the intestine, and have no efferent ducts. The testis alone is generally present in this
position in the adult. The ovary, which was discovered by Fol, developes later than the
testis.

As this section is intended to be merely anatomical, and as the Challenger collection
has thrown no direct light upon the embryology of the group, it is considered unnecessary
to attempt here a brief account of the process of development in an Ascidian, the more so,
as such an excellent epitome of all the best work upon this subject has been published
recently in Balfour's "Comparative Embryology," vol. ii. pp. 8 to 19.

Gemination.

Reproduction by means of more or less complicated processes of gemmation is preva-
lent in all groups of the Tuuicata, with the exception of the Appendiculariidse and the
Ascidife Simplices. Among the latter it is found, however, in the family Clavelinidse,
where it results in the formation of small societies (PI. XXXVI. fig. 2), the members
of which may either remain connected by a common vascular system, or more rarely {e.g.,
sometimes in Clavelina), may lose this connection and become independent.

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

The buds in the Tunieata are formed as outgrowths from the parent body, consisting,
probably in all cases, of part of the mantle covered by the ectoderm and enclosing a diver-
ticulum from some part of the alimentary canal. In this way portions of the hypoblast,
mesoblast, and epiblast of the parent are implicated, and these layers probably give rise
to the different systems of organs in the bud in much the same way as they do in the
embryo.

Further details as to the process of gemmation are deferred till the second part of
this Report, which will treat of the Compound and Pelagic Tunieata, among which some
form .of budding and metagenesis is almost universal.

DESCRIPTION OF THE SPECIES.

ASCIDLE SIMPLICES.

The Ascidise Simpliees, in which I include the Clavelinidse, may be denned as solitary
or social, fixed or free, but never free-swimming, Ascidians, which may reproduce by
gemmation so as to form societies of Ascidiozooids united by a common vascular system,
but in which each has a distinct test, and is not imbedded along with the other Ascidio-
zooids in a common investing mass.

This suborder, then, includes those Ascidians which are never free-swimming and arc
never imbedded in a common colonial mass. They are usually solitary, and reproduce
only in a sexual manner. In at least one family, however, reproduction takes place also
by gemmation, which results in the formation of small colonies or " societies," but in
these the different ascidiozooids are perfectly distinct, and their tests are not united into
a common investing mass, as in the Ascidise Composite. They are merely joined by
their posterior ends, usually by the intervention of a creeping stolon containing blood-
vessels, so that the different members are connected by a colonial circulatory system.

This family, the Clavelinidse, has usually been considered as a distinct suborder
(Ascidise Sociales), of equal rank with, and intermediate between, the Ascidise Simpliees
and the Ascidia? Composite ; while it has sometimes been united with the last-named
group to form the suborder Synascidiae. I have already, in the Preliminary Report,1 given
in detail my reasons for placing the Clavelinidse in the Ascidise Simpliees.

The Ascidise Simpliees may be divided into four families — the Molgulidse, the
Cynthiidaa, the Ascidiidaa, and the Clavelinidse. In the last of these, gemmation and
the formation of a colony take place ; while in the others, although the apparatus for
budding — the " blood-vessels " of the test — is present, and may even be developed into
stolon-like processes, so far as is known buds are never formed. In this property, the
power of reproducing by gemmation, the Clavelinidse differ from the other Ascidiaa
Simpliees ; otherwise they closely resemble the Ascidiidse, such genera as Ecteinascidia,
Ciona and Rhopalcea forming a passage from the one family to the other.

The Cynthiidse and the Molgulidae are more nearly allied to each other than to the
Ascidiidse, which family is less highly developed and less complex in organisation than
the two former. The Molgulidse are probably the most highly differentiated and most
elaborately complete in all their parts, while the Clavelinidas may be considered as the

1 Proc Roy. Soc Ediii., 1879-80, p. 714.

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

simplest and least developed forms, and through them must be traced the passage to the
Ascidise Compositse.

The relations between these families of Simple Ascidians may, according to our
present knowledge, be expressed serially thus : —

MOLGULID^E — CYNTHIID.E — AsCIDIIDiE — ClAVELINID^E.

Family Molgulid.e.

Body usually free, sometimes fixed, rarely pedunculated.

Test cartilaginous, coriaceous, or membranous, often covered with sand. Branchial

aperture, six-lobed ; atrial aperture, four-lobed.
Branchial Sac longitudinally folded ; internal longitudinal bars not papillated ;

stigmata more or less curved, usually arranged in spirals.
Tentacles always compound, usually much branched.
Intestine attached to the inner surface of the mantle on the left side.
Renal Sac present, upon the right side of the body.
Genitalia on the inner surface of the mantle, usually developed on both sides.

This is the highest and most complex family of the Ascidise Simplices. It is closely
allied to the Cynthiidse, from which it was first distinguished by Lacaze-Duthiers in 1877. 1

Heller,2 who had previously divided the Ascidias Simplices into families, arranged
Molgtda and its allies under the Cynthiidas ; there can be no doubt, however, that the
two groups of genera should be considered as independent families. Lacaze-Duthiers
(loc. cit.) discusses this question at length, and after pointing out the resemblance between
Cynthia and Molgula he shows clearly the distinctions between the two forms, and
establishes and defines the family Molgulidse.

The most constant and most generally useful characteristic is, as usual, to be found in
the configuration of the apertures. The branchial aperture has always six lobes, and the
atrial has always four. There are several other external characters, but none are so reliable
as these. The animal is usually free, or imbedded in mud or sand ; sometimes, however,
it is fixed like other Simple Ascidians, and a few of the newly discovered forms are
pedunculated.

The outer surface of the test is usually covered by a thick coating of sand grains and
shell fragments adhering to long hair dike processes of the test. Some Molgulidae, how-
ever, have perfectly smooth tests with no adhering sand, while on the other hand some
of the Cynthiidaa {e.g., Polycarpa molgidoides) exhibit the delicate hairs and thick sandy
coating of a typical Molgula.

The branchial sac, like that of the Cynthiidse, is longitudinally folded ; here, however,

1 Les Ascidies Simjjles des cotes de France, Arch. Zool. expfr., t. vi. p. 457.

2 Untersuchungen iiber die Tunicaten des adriatischen und Mittelmeeies, Abtli. iii. p. 1.

REPORT ON THE TUNICATA. 59

the folds are more constant in number and position. There arc almost always the same
number of folds on each side,1 and that number is either five (Molgula crystallina,
Miller), six, or seven — usually the latter. Large papilla' on tin' internal longitudinal
bars, like those characteristic of the Ascidiidaa. are never seen. Usually the bars are
perfectly smooth, but in a few species minute projections, evidently corresponding t<>
papillae, are present.

In a typical Molgula the arrangement of the stigmata is very peculiar. Each fold
projecting from the inner surface of the branchial sac is formed of a longitudinal series
of conical bags, having square external bases, and pointed internal apices, which may be
branched. The stigmata form spiral slits more or less interrupted, extending from the
base to the apex of this bag or infundibulum, as Lacaze-Duthiers names it.

The flat spaces lying between the rows of infundibula have their stigmata more
irregularly arranged, but still curved, and usually having an indistinctly marked spiral
disposition. In some of the new forms this typical arrangement is not found, the stigmata
being irregularly disposed though still curved, but occasionally almost straight.

The tentacles are compound, and are very like those of the Cynthinse and Bolteninse.
Lacaze-Duthiers mentions as characteristics of tbe Molgulid tentacles the greater number
of secondary and tertiary pinnules, their more irregular size, and less tapered extremi-
ties, and most important of all the raising up of the membrane covering their inferior
or branchial surface into puffed-out projections and folds.

The appearance of the intestine is rather characteristic of the Molgulidaa. It is firmly
attached to the mantle on the left side, and is so sunk in it that it becomes very clearly
visible from the outer surface, and seems to be in the middle of the thickness of the mantle.
The genitalia are placed on the inner surface of the mantle, and are usually developed
on both sides. On the left side the gland is close to the intestine, on its anterior edge,
however, not in the loop. The opposite gland, which is absent in the genus Eugyra,
occupies the centre of the right side ; while posteriorly to it lies the heart, separating
the genital gland from the renal organ, which has rather a characteristic appearance in
the Molgulidse, being a compact and more or less solid organ placed near the inner Burface
of the mantle towards the posterior end of the right side.

The following genera have been at various times referred to this family : — Molgula,
Eugyra, Ctenicella, Anurella, Glandula, Gymnocystis, Pera, Lithonephrya, Ccesira,
and Ascopera. Of these Molgula, Eugyra, and Ascopera are represented in the Chal-
lenger collection.

Ctenicella was founded by Lacaze-Duthiers in 1877, and is probably a good genus.
I have found it impossible, however, to accept his Anurella. It is distinguished from all
other Molgulidse by the remarkable structure of the larva, which is "amoeboid" and

1 In Molgula pyriformis (see page 79) there are seven folds on the ri^Ut Bide and six on the left It is possi I
however, that this may be an individual peculiarity.

(ZOOL. CHALL. EXP. PART XVII. 1SSJ.) R 9

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

tail-less.1 This most interesting developmental difference does not seem to be accom-
panied by any structural peculiarities in the adult form, which apparently does not
differ generically from Molgula.

Glandula, as I pointed out in the Preliminary Eeport,2 does not belong to the
Molgulidae, but should be placed in the sub-family Styelinse of the Cynthiidse.

Gymnocystis was founded by Giard in 1872 3 for van Beneden's Ascidia ampulloides,
which has been so often described, and referred to so many different genera. This species
is undoubtedly one of the Molgulidse, but I see no reason for separating it from Molgula.
Giard distinguishes it chiefly on account of the test, which is smooth and semi-cartila-
ginous, like that of some species of Ascidia. This kind of test is, however, found
in several undoubted species of Molgula (e.g., Molgula gregaria, Lesson), and graduates
into the condition characteristic of the genus. I agree, therefore, with Lacaze-Duthiers
in referring van Beneden's Ascidia a/m/pvlloides to the genus Molgula.

Pera, Stimpson, is probably either a Molgula, or an Eugyra. Nothing in the
description warrants our considering it as the type of a new genus. The species
described by Macdonald,4 from the Bellona reefs, under the name of Pera huxleyi seems
to be a Rhodosoma, and in that case belongs to the Ascidiidse.

Lithonephrya is characterised by Giard5 as having the renal organ occupied by a
large brown concretion. Otherwise it seems identical with Molgula.

Under the names of Ccesira parasitica, Ccesira Jicus, and Ccesira pellucida, Macdonald °
described in 1859 three species of Simple Ascidians from Australia. They are evidently
Molgulidae, but whether or not they differ generically from Molgula and Eugyra is very
doubtful. The tribe Cynthise Caesirse of Savigny includes the single species Cynthia dionc,
which seems from the figures and description,7 notwithstanding the assertion that both
apertures are four-lobed, to belong to the Molgulidae, and probably to the genus Molgula.
Heller 8 states that its nearest ally is Stimpson's Glandula. I cannot endorse this, as
the latter genus is closely allied to Styela, while I consider Savigny 's Cynthia dione a
species of Molgula.

Ascopcra was founded 9 for the reception of two very large new species from the
Antarctic. They are attached, pedunculated, and not incrusted ; the chief peculiarity,
however, is in the branchial sac, as the stigmata are never arranged in spirals, no
infundibula being present.

1 See Lacaze-Duthiers, Ase. Simp, des cotes de France.

2 Proc. Roy. Soc. Edin., 1880-81, p. 231

3 Archives de Zoologie experimentale et generale, t. i. p. 405.

4 J. D. Macdonald, Jour. Proc. Linn. Soc, 1862.

6 Arch, de Zool. exper., t. i. p. 404.

0 J. D. Macdonald, Trans. Linn. Soc, vol. xxii. p. 367.

7 Mem. sur les Anim. sans Vert., p. 153, pi. vii. tig. 1.

8 Unlemu'h. u. d. Tun. d. adriat. u. Mittelmeer. , Abth. iii. p. 2.
3 Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 238.

REPORT ON THE TUNIC ATA. (51

Eugyra differs from Molgula chiefly in having no true folds in the branchial sac.

and in having only a single genital gland, placed beside the intestine on the left side of
the body.

The following shows the genera of the family in a tabular form : —

Molgulim:.

Branchial sac folded
1

aper

tures

Branchial sac not folded

1

; apertures laciniated

i
Ctenicella.

Lobes of the
1

Eugyra

plain

Stigmata always
spirally

more
coiled

or less

1

Stigmata curved or straight,

never in spirals

Molgula. Ascopera.

Ascopera, Herdman.
Ascopera, Herdman, Preliminary Report, Proc. Roy. Soc. Ediu., 1S80-S1, p. 238.

Body more or less pyriform, pedunculated, attached.

Test thin, between membranous and leathery in texture, having no adhering sand

and no hair-like processes.
Branchial Sac with seven folds on each side. Stigmata straight or curved, but

not arranged in spirals.
Tentacles compound.
Genitalia developed on both sides. The gland on the left side lies ventrallv to

the rectum.

This genus is closely allied to Molgula, and has the chief characters of the family \ ery
well marked. The branchial aperture is sixdobed, and the atrial four-lobed ; the
branchial sac has seven longitudinal folds on each side ; the tentacles are compound, and
a distinct renal organ is present, lying on the right side posteriorly to the genital gland.
The external appearance, however, is not suggestive of a Molgula. The body is pedun-
culated, and was evidently attached by the posterior end of the short stalk while the
outer surface of the test is not incrusted with sand and bears no hair-like processes.

The arrangement of the stigmata in the branchial sac differs considerably in the two
species, but in neither are they disposed in spirals, as no true infundibula are present.

The intestine lies upon the left side of the branchial sac and runs an tero- posteriorly ;
it has a large genital gland at its ventral edge, while the other genital gland is situated
in the centre of the right side, projecting from the inner surface of the mantle.

<;•_> THE VOYAGE OF H.M.S. CHALLENGER.

There are two species in the genus, Ascopera gigantea with a large body and a short
peduncle, and Ascopera pedunculata with a small body and a much longer peduncle.

Ascopera gigantea, Herdman (PL I., PI. II. figs. 1-4, and PI. III. figs. 3-5).

Ascopera gigantea, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 238.

External Appearance.- — The shape is somewhat pyriform, and not compressed laterally.
The anterior end is wide, truncated, slightly cleft in the centre, and ends in a siphon at
each extremity. Behind the siphons the body swells out into a globular form, attaining its
greatest width at about two-fifths of its length from the anterior extremity; it then narrows
to become the wide peduncle constituted by the posterior two-fifths. The edges are both
convex, but the dorsal is more so than the ventral, especially towards its posterior end.
The animal is attached by the lower (posterior) end of the stalk.

The apertures are both at the anterior end ; they are distant, conspicuous, tubular,
and prominent. The branchial is at the end of a projection from the ventral edge of the
anterior end, in the form of a wide tube bent round posteriorly so as to present a convex
surface anteriorly and an open mouth posteriorly. The aperture is large and funnel-
shaped, and is bounded by six wide, low, undulated lobes separated by slight clefts. The
atrial aperture is placed at the summit of a projection from the dorsal edge of the
anterior end. This projection is larger than that on which the branchial aperture is
placed, and extends further forwards, thus rendering the atrial aperture more anterior
than the branchial. The aperture is wide, quadrangular, and directed anteriorly.
It is bounded by four lips with slightly undulated edges.

The surface of the body is even, there being no projections or marked irregularities.
It is not, however, perfectly smooth, being finely roughened all over.

The colour is a pale yellowish grey-green, with a slight tinge of brown towards the
lower end of the peduncle.

Entire length (antero-posterior), 30 cm. ; length of peduncle, 10 cm. ; greatest breadth
,(across apertures), 15 cm. ; breadth in middle of body (dorso-ventral), 12 cm.

The Test is thin and almost membranous, but tough. It is semi-transparent, and is
slightly roughened externally, but quite smooth on the inner surface.

The Mantle is delicate and membranous, with a few distant rather strong muscle bands
running transversely over about the anterior half of the right side and the left side ; they
are only absent on the dorsal part of the left side and the posterior end. At the posterior
end of the body, where the peduncle commences, the mantle is firmly united to the test,
even after immersion in alcohol.

The Branchial Sae is extremely thin and delicate, and has seven folds on each side;
those next the endostyle are rather slighter than the others. The internal longitudinal
bars are wide but delicate. The transverse vessels are also wide, and all of one size. The

REPORT ON THE TUNICATA. 63

internal longitudinal liars and transverse vessels give off trunks which branch and
anastomose, forming an irregular but close network, the meshes of which are the stigmata.

The Dorsal Lamina is a plain membrane, short, 4 mm. wide, and rather thick. There
are no ribs nor teeth.

The Tentacles are compound and large. There are eight larger and eight smaller
placed alternately, and about sixteen very minute ones intermediate to the others.

The Dorsal Tubercle is large and prominent. Both horns are much coiled, forming
conspicuous spirals.

The Alimento.ry Canal is placed on the left side of the branchial sac, lying antero-
posteriorly. The oesophagus is short and narrow ; the stomach is small and pyriform ;
the first part of the intestine is large, and turns round posteriorly to form a narrow-
loop ; the rectum runs parallel to the intestine and stomach, and is very narrow.

Genitalia are developed on both sides. The gland on the left side is sausage-
shaped, and lies parallel to the rectum on its ventral edge. The gland on the right side
is similar in shape, and is placed in front of the curved renal sac.

This is the largest Simple Ascidian with which I am acquainted. The figure (PI. I.
fig. 1) is only about three-quarters of the natural size, but otherwise it gives a very good
idea of this singular animal. The most notable points in the external configuration arc
the globular central part of the body, the narrow posterior part forming the peduncle, the
wide anterior end, and the two apertures — the atrial, the more anterior of the two, and
the posteriorly directed funnel-like branchial. Both are very wide, and it seems almost
impossible that the animal should ever be able to close them completely.

The test is remarkably thin and membranous for an Ascidian of such a size. It is,
however, very tough. It thickens towards the edges of the apertures and on the peduncle
while the thinnest region is in the centre of the right and left sides. It is very finely
roughened all over, so as to have a minutely granular texture, while at the posterior end
there are a few slight processes for attachment to stones (PI. I. fig. 1).

Thin sections show that the matrix is homogeneous, and contains large numbers of
very small bladder-cells often aggregated in heaps (PI. II. fig. 4 bl.), and minute globular,
fusiform, and stellate nucleated protoplasts (t.c).

The mantle is also very delicate, and the musculature is feeble. None of the short-
bellied muscles so characteristic of the mantle in the typical Molgulidse are found.
Sphincter muscles are present, but they arc not of great strength (PI. I. fig. 1, atrial
aperture).

The branchial sac is most remarkable, and ismuchthe most delicate form known. Its
tenuity is such between the folds, that when raised on a fine paint brush it seems like a
sheet of mucus, and scarcely holds together. It is perfectly transpar< at, and requires i<>
be stained before the structure can lie made out. PI. HI. fig. 3, represents a small

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

portion of the sac slightly enlarged, and shows the wide, but very thin transverse
vessels (tr.), and internal longitudinal bars (i.l.). One of the longitudinal folds is here
seen (br.f.), and it shows nine internal longitudinal bars, four on each side and one at the
ed^e. It is obvious from the figure how the space between two adjacent bars decreases as
you work along the fold from tbe large mesh (ink.) of the space between the folds to the free
edge of the fold. PI. II. fig. 1, represents a portion of the branchial sac more magnified
to show the complicated branching and anastomosing of the vessels, and the way in which
the stigmata lie in different planes, there being in some places as many as three systems of
vessels crossing one behind the other. A small part is shown very highly magnified in
PI. II. fig. 2, to exhibit the stigmatic ciliated cells ; over the greater part of the
vessels of the sac the cilia have been lost. Figure 3 shows a small part of the surface of
a vessel still more highly magnified ; the epithelium is squamous, and the cells are large,
delicate, and distinctly nucleated. PI. III. fig. 4, shows a part of the branchial sac
where the stigmata are much more regular, the smaller vessels being; less curved. This
is distinctly an approach to the arrangement of the stigmata in Ascopera 'pedunculata.

The dorsal lamina (PL III. fig. 5, and PI. I. fig. 2, d.l.), is wide, but short. There are
eight large and strong tentacles (PI. III. fig. 5), and the same number of much smaller
ones, while, alternating with these sixteen, there are about the same number of very
minute but still compound ones. The dorsal tubercle (PI. III. fig. 5, d.t.), is large, and
much coiled. There is no distinct peritubercular area.

The oesophageal aperture (PI. I. fig. 2) is situated far forward in the branchial sac,
and is ear-shaped, with a double lip on the right side. It lies on a flat triangular area at
the posterior extremity of the dorsal lamina, at the point of convergence of the fourteen
branchial folds (see PI. I. fig. 2, 1-7). The oesophagus (PL I. fig. 3, oe.) is short,
cylindrical, and rather narrow. It runs directly posteriorly, and opens suddenly into the
wider end of the small pyriform stomach (st.). At the posterior narrower end of the
stomach the wide intestine commences. The wall of the stomach is thick, and its outer
surface is rough from the presence of a number of small rounded projections. This
structure is continued on to the first portion of the intestine, but soon dies away ; and the
rest of the tube has a thin membranous wall through which the coiled faecal masses are
distinctly seen. The wide intestine runs directly posteriorly from the stomach for a
considerable distance ({.), then turns round ventrally, and, after running for a short
distance anteriorly, turns at right angles dorsally, so as to come in contact with the first
part of the intestine. Here the tube, which may now be called the rectum (/•.), becomes
very narrow, and during the remainder of its course lies in close contact with the first
part of the intestine, the stomach, and finally the oesophagus.

Along the ventral edge of the rectum lies the large, yellow, sausage-like, genital
gland (PL I. fig. 3, g.) with its axis directed antero-posteriorly. The duct is of moderate
length (g.d.) and projects from the anterior end, opening into the peribranchial cavity,

REPORT ON THE TIXK'ATA. 65

but at a considerable distance from the atrial aperture. The gland on the right side is
similar in size and shape. It is 4"5 cm. in length (antero -posteriorly) and 1*5 cm. in breadth,
while the membranous duct extends from the anterior end for a distance of 1*3 cm.

One large specimen of this species was obtained to the south of Kerguelen Island,
at Station 150, February 2nd, 1874; lat. 52° 4' 8., long. 71° 22' E. ; depth, 150
fathoms; bot. temp., 1°"8 C. ; hard ground.

Ascopera pedunculata, Herdman (PI. II. fig. 5, PI. III. figs. 1 and 2).

Ascopera pedunculata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 239.

External Appearance. — This species is club-shaped, and consists of an ovate or
roughly diamond-shaped body, somewhat compressed laterally, and borne on the summit
of a thick peduncle. The anterior end is straight, wide, and truncated, and is continued at
its extremities into the branchial and atrial siphons. The dorsal and ventral edges arc
nearly straight, and slope outwards and backwards to the wide posterior end. Both arc
slightly convex, and the dorsal is the shorter and more curved of the two, while the
ventral is straighter and longer. The posterior end is wide, straight, and obliquely
truncated, sloping backwards and ventrally. It joins the dorsal edge by a continuous
gentle curve, and at its ventral edge is prolonged into the large peduncle, which is twice
as long as the body, but thin, being compressed laterally. It is narrow where it joins
the posterior end of the body, but increases gradually in breadth as it proceeds backwards,
till at the posterior end, wdiere it is attached to the bottom, it is more than twice as
broad as at the anterior end.

The apertures are at the extremities of the anterior end, moderately distant, con-
spicuous, slightly projecting, and distinctly lobed. The branchial is at the ventral edge
of the anterior end, and has its six-lobed siphon bent so that the opening looks
directly ventrally. The atrial is at the dorsal edge, is four-lobed, and has the siphon
not so prominent as that of the branchial, and not bent, the aperture being directed
dorsally and slightly anteriorly.

The surface is even, there being no marked irregularities. The body, however, is
slightly and regularly roughened all over, so as to have a granular appearance. The
stalk is smooth. The colour is pale grey.

Length of body (antero-posterior), 7 cm. ; breadth of body (dorso-ventral), 7 cm. ;
length of peduncle, 17 cm. ; breadth of peduncle, 4"6 cm.

TJie Test is somewhat leathery; it is moderately thick and tough on the body, but
very thin and membranous on the peduncle. It is almost opacpie on the body, but trans-
parent on the peduncle. It is smooth on the inner surface.

The Mantle is thin and membranous, or in parts semi-gelatinous. The posterior part
is prolonged for 13 cm. into the peduncle. The musculature is feeble.

The Branchial Sac is delicate, and has seven folds on each side. The internal longitu-

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

dinal bars are wide, but delicate, and not distant. The transverse vessels are rather irregu-
lar, and there are generally several smaller vessels of different sizes placed between each pair
of larger ones. Frequently the smaller vessels do not extend the entire breadth of the
mesh. The meshes are somewhat variable. Considered as extending from one larger trans-
verse vessel to the next, they are generally elongated antero-posteriorly, but may be square
or even elongated transversely. The stigmata are of different lengths, and often run across
(behind) the transverse vessels ; they are generally straight and all placed longitudinally.

The Dorsal Lamina is broad but thin and short ; it is quite plain, with no ribs nor teeth.

The Tentacles are compound and large, sixteen in number, and of two sizes placed
alternately.

The Dorsal Tubercle is prominent, elongated transversely, and having the aperture
at the right side. The horns are large, and both coiled outwards.

The Alimentary Canal, as in the preceding species, is on the left side of the branchial
sac, lying antero-posteriorly, and chiefly along the dorsal edge and the dorsal part of the
posterior end.

Genitalia are present on both sides of the body. The gland on the left side lies ven-
trally to the intestine, whde the other genital gland occupies the centre of the right side.

This species, though agreeing with Ascopera gigantea in all important characters,
has a very different appearance (PL III. fig. 1). The proportion between body and
peduncle is the reverse of that which obtains in the last species, the peduncle beino- here
twice as long as the body. The body is somewhat similar in appearance, though much
smaller and more compressed laterally. The apertures are placed at the extremities of the
anterior end, but the atrial is turned up so as to be directly opposed to the peduncle which
arises from the ventral edge of the posterior end. Hence there is a liability to consider
the atrial aperture as forming the anterior extremity, and the peduncle the posterior, and
one is greatly tempted to describe the animal in this position. It would, however, be
distinctly an error, as the morphological anterior end is always indicated by the branchial
aperture, and the dorsal edge is that side on which the nerve-ganglion (or, for convenience
in practice, the atrial aperture) is placed. In the present case it would make an immense
difference and cause utter confusion to follow what seems the natural enough course of
considering the two opposite ends of the animal as anterior and posterior (in place of call-
ing the one the dorsal edge of the anterior end and the other the ventral edge of the pos-
terior end), as what is really the ventral edge, that on the extremity of which the branchial
aperture is placed (PI. III. fig. 1), would then become the dorsal, and the right and left
sides of the animal would also be transposed. This explains the apparent abnormality of
the principal viscera being placed on what seems the right side.

The test over the surface of the body is rather stronger than that of Ascopera
gigantea, but in the peduncle, on the other hand, it is much thinner.

REPORT ON THE TTJNICATA. 67

The mantle is thin, and towards the posterior end becomes semi-gelatinous, and
forms a solid tail-like body, which projects for a considerable distance into the large
hollow of the peduncle. In the spirit specimen this " tail " was much contracted, and did
not nearly fill up the hollow, with the walls of which it had no connection at any point.
In minute structure it is not unlike the test, but is covered externally by a complete
layer of squamous epithelium (the ectoderm) formed of diamond-shaped or short fusiform
cells. There is a homogeneous matrix containing numerous rounded, fusiform, irregular,
and stellate protoplasts, often crowded together. Here and there sinuses containing
blood-corpuscles are met with.

The branchial sac (PI. II. fig. 5) seems at first sight very different from that of
Ascopera gigantea, but a comparison with the part of the latter represented on PI. III.
fig. 4, shows that the two are not so very different after all, although the arrangement in
the present species is much more regular, and the stigmata are less curved, and run
longitudinally, thus causing the sac to have rather a Cynthiad appearance. Molgulid
characteristics are seen, however, in the irregularity in the length of the stigmata, in the
way in which they cross behind the transverse vessels, thus appearing to break up the
latter, and in the occasional presence of very delicate short transverse bars crossing the
stigmata between the adjacent fine longitudinal vessels (PI. II. fig. 5).

The dorsal tubercle has rather a remarkable appearance (PI. III. fig. 2), being placed
transversely, and elongated, so that its hollow is deep and narrow, while the horns are
large, turned outwards (one anterior, and one posterior), and equally coiled.

The oesophageal aperture is situated far forward in the branchial sac, not far from
the atrial aperture. The intestine, as in Ascopera gigantea, forms a long narrow loop,
the rectum being parallel to the first part of the intestine.

The genital gland on the left side lies on the ventral edge of the rectum, and is large,
of a bright yellow colour, and more irregular in shape than that of Ascopera gigantea.

The gland on the right side lies near the ventral edge, is large, and elongated antero-
posteriorly. Behind it is situated the crescentic thin-walled renal sac.

One specimen was obtained in the same locality at which Ascopera gigantea was found,
to the south of Kerguelen Island, at Station 150, February 2, 1874; lat, 52° i' S.,
long. 71° 22' E. ; depth, 150 fathoms; bot, temp., l°-8 C. ; hard ground.

Molgula, Forbes.

Ascidia, Miiller, Zool. Dan., vol. iv. 180G. In part.

Molgula, Forbes, History of British Mollusca, vol. i. p. 3G. 1853. In part.
Molgula, Kupffer, Jahresber. der Commiss., &c, p. 223. 1875. In part.
Molgula, Heller, Untersuch. ii. d. Tun. d. Adriat. Meer., Al.th. iii. p. 27. 1877.
Molgula and Anurella, Lacaze-Duthiers, Asc. Simp, des cotes de Fiance, p. 568.
Molgula, Traustedt, Oversigt over de lia Danmark og dets nordlige Bilande kjendte Ascidise
Simplices. Vidensk. Medd. Xat. Fon-n. i Kjoli.-idiaui, 187'J H>, p. 121. ISsO.
(zool. chall. exp. — part xvn. — 1882.) l; 10

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

Body usually globular, attached or free, often incrusted with sand. Branchial

aperture six-lobed, atrial four-lobed.
Test usually thin but tough, often having hairs on the outer surface.
Mantle thin and membranous ; musculature usually feeble ; consisting chiefly

of long radiating bundles arising from the sphincters, and of short fusiform

clumps of fibres scattered through the mantle.
Branchial Sac folded longitudinally ; stigmata more or less curved, coiled spirally

in infundibula.
Tentacles compound.

Alimentary Canal on the left side of the branchial sac.
Genitalia developed on both sides.
Renal Organ in the form of a crescentic sac placed in the centre of the right side

of the mantle, and usually containing concretions.

This genus has been so fully discussed recently by Lacaze-Duthiers in his great
monograph on the Molgulidee 1 that it seems superfluous to give a detailed account here
of the general characters. A few special points, however, require to be mentioned. As
is stated above, I have found it impossible in dealing with this collection to recognise
Lacaze-Duthiers' genus Anurella, on account of the absence in the adult animal of any
characters distinguishing it from Molgula.

None of the distinguishing features of the genus Molgula can be derived from the
external appearance. Most of the species are globular and unattached, but on the other
hand some are elongated, and some quite irregular in shape ; some are attached, and some
are even shortly pedunculated. The condition of the test also furnishes no criterion.
Typically it is thin and membranous, but covered with sand-grains attached to long
hair-like processes. Molgula gigantea has its posterior half in this condition, but the
anterior part is perfectly smooth and has no incrusting sand, while Molgula pyriformis
is perfectly free on the entire surface both from adhering sand and hairs.

The musculature of the mantle is characteristic for many of the species, but does not
hold for all. It is feebly developed on the whole, leaving the mantle transparent
(PI. V. fig. 9), and consists chiefly of (1), the sphincters round the apertures, which are
clearly defined and of moderate strength ; (2), a series of longitudinal bundles, which radiate
from the lower edge of each of the sphincters, and gradually die away as they recede
from the apertures ; and (3), of bundles of fibres scattered over the general surface of the
mantle. These last are partly the ordinary narrow greatly elongated bands found in other
groups, but they are chiefly a characteristic form found only in the Molgulidas, namely
short fusiform clumps consisting of from two to a dozen, but generally four to six, thick
short fibres closely united and tapering rapidly towards both ends so as to form a

1 Les Ascidies Simples des cotes de France.

REPORT ON THE TUNICATA. 69

spindle-shaped bundle. These fibres are usually of a clear yellow colour, and at the ends
they become continuous with a very long delicate transparent fil.re, which runs usually
for a great distance through the mantle, and may either die away or may join a similar
filament from another bundle. The whole arrangement is rather suggestive of a muscle
with a belly and two long tendons as seen in higher vertebrates.

The chief features in the branchial sac of Molgula are the distinct folds and the more
or less curved stigmata arranged in infundibula.

The alimentary canal is always situated on the left side of the branchial sac, and has
one of the genital glands in its neighbourhood, the other being placed near the centre
of the opposite side of the mantle, and always anterior to the sacdike renal organ
(PI. IV. fig. 7).

The Challenger collection contains six species of this genus, four of which were nev.
to science.

Molgula gigantea, Cunningham (sp.) (PI. IV. figs. 1-4).

Cynthia gigantea, R. 0. Cunningham, The Nat. Hist, of the Straits of Magellan, Edin. 1871.
Cynthia gigantea, R. O. Cunningham, Notes on the Reptiles, &c., obtained during the voyage of

H.M.S. " Nassau," Trans. Linn. Soc., vol. xxvii. p. 489.
Molgula gigantea, Herdman, Preliminary Report, part iv., Proc. Roy. Soc. Edin., 1880-81, p. 234.

External Appearance. — The body is oblong or oblong-ovate in shape, often cylindri-
cal, and usually compressed laterally. The anterior end is usually narrowish, but truncated
and flat. The posterior is rounded, usually broader than the anterior, and sometimes
irregular ; the dorsal and ventral edges are gently convex, and about erraal in length.

The apertures are both at the anterior end ; they are moderately distant, conspicuous,
and slightly projecting. The branchial is at the ventral edge of the anterior end, on a
distinctly sixdobed teatdike projection, and usually bent so that the aperture joints
ventrally and somewhat posteriorly. The atrial is at the dorsal edge of the anterior end ;
it is not so prominent as the branchial, is four-lobed, and directed more or less anteriorly.

The surface is even and moderately smooth in the upper part. The lower half is
thickly incrusted with sand attached to fine hair-like processes of the test.

The colour in the upper part is usually a pale slate-blue.

Length of body (antero-posterior) in a specimen of medium size, 19 cm. ; breadth of
body (dorso- ventral), 10-5 em. ; thickness of body (lateral), 7'5 cm.

The Test is coriaceous, and rather thin but tough; it is opaque, and smooth in the
upper (anterior) part, but bears hairs on the posterior part, to which sand grains are
attached, forming an incrusting coat.

The Mantle is thick ; and the musculature is strong, especially along the dorsal and
ventral edges.

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

The Branchial Sac is very thick and strong, with seven large folds on each side.
The transverse vessels are very large, few, and visible to the eye. They give off numer-
ous branches, which divide and anastomose, forming a network of wide vessels which form
the meshes of the sac. These vessels give off much smaller tubes which bound the
stio-mata. The stigmata are numerous, irregular, and arranged in spirals forming
infuudibula.

The Dorsal Lamina is a short but very broad membrane, with no ribs, but having
an irregular margin.

The Tentacles are compound, and large ; they are sixteen in number, and of two
sizes, placed larger and smaller alternately.

The Dorsal Tubercle is large and prominent, with both horns much coiled spirally.

This large species was obtained by Professor E. 0. Cunningham in the Straits of
Magellan during the cruise of the " Nassau," and was briefly described under the name of
Cynthia gigantea in the Transactions of the Linnsean Society of London for 1871.

Cunningham's description merely refers to a few features in the external appear-
ance, and is insufficient for the identification of the species. It was only when
examining the " Nassau " collection in the British Museum that I discovered that the
large Challenger Molgula from the Straits of Magellan was identical with Cunningham's
Cynthia gigantea, which had been referred to the wrong genus and family ; consequently,
while retaining the old specific name, I have treated it otherwise as a new species, and
have figured and described it anew in detail.

The external form is somewhat variable ; some specimens are almost globular, and
others fusiform, while all intermediate shapes occur. The specimen figured (PL IV. fig. 1 )
is typical as to shape, but is of small size. Cunningham mentions that the largest
specimen obtained by the " Nassau " measured " eight inches from base to apertures,
and was between four and five inches broad." Many of the Challenger specimens exceed
those dimensions, the largest being 33 cm. in length, and 17'5 cm. in breadth. This is
the next largest Simple Ascidian to Ascopera gigantea.

The following list shows the proportions between length and breadth in thirty of the
Challenger specimens : —

.

Length

Breadth

Specimen.

Length

Breadth

:imen.

(anteroposterior).

(dorso-ventral).

(antero-posterior).

(dorso-ventral)

1

5 '5 cm.

4 cm.

10

10 cm.

6

cm.

2

6 „

5 „

11

10 „

7

>j

3

6-5 ,

4 „

12

13 „

9

3)

4

7 „

4 „

13

13-5 „

9

>»

5

7 »

4-5 „

14

14 „

8

>»

6

7 „

6 „

15

15 „

7

)»

7

8 „

4 „

16

16 „

10

II

8

9-5 „

5-5 „

17

18 „

9

I*

9

10 „

5 „

18

18-5 „

10

3)

itKi'oirr on tiii: Trxic \r \.

71

P 1 Til P 11

Length

Breadth

1 i 1 1 1 ' i 1 .

(antero-

losterior).

(dc

rso-ventral)

1!)

19

cm.

10-5 cm.

20

19

?>

13 „

21

20

>)

9 ,,

22

20

)j

10 „

23

21

?j

12 „

24

24

>j

15 „

Length

Breadth

CIlIH'I).

(anteio-posterior).

(dorso-ventral)

25

25

cm.

1 1 cm.

26

26

»)

13 „

27

26

>>

15 „

28

29

»>

14 „

29

30

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17-5 „

The test is leathery in texture and is rather thin (varying from "3 to 3 ram.) but very
tough. It is quite opaque. In the upper (anterior) part, in young specimens, it is smooth
and shining, while in older ones it is wrinkled and somewhat irregular and rough. A large
part of the posterior end, varying from one-third to two-thirds (and even in some specimens
to three-quarters on the left side, which is always more incrusted than the right) of the total
length, bears numerous long delicate hairs to which sand is attached (PI. IV. fig. 1) in
such quantity as to form towards the posterior end a solid coating often 6 mm. in thick-
ness. As Cunningham observed there are frequently quantities of Hydroids, Polyzoa, and
Compound Ascidians attached to the outer surface of the test.

It varies greatly in colour. In young specimens it is a pale greyish blue or slate
colour, and is smooth and shining ; while in older specimens, where it is rough and irregular,
the colour is much darker, and varies from a dirty blue to brown.

In minute structure the test is composed of a translucent matrix in some places
homogeneous, but generally slightly fibrillated, especially near the inner surface where the
fibres are distinct and run parallel to the surface. In this matrix lie minute rounded
protoplasts and a few larger bladder-cells, and towards the outer surface numbers of yellow
and brown pigment cells, forming a distinct dark-coloured zone. Vessels are present here
and there, but are evidently feebly developed. The inner surface is lined by a layer of
columnar epithelium (the ectoderm).

The mantle is rather thick, except on the centre of the right and left sides where it
becomes membranous. The muscle bands are yellow, and are numerous and stout. They
are especially developed on the branchial and atrial siphons, forming powerful sphincters,
over the anterior end, down the dorsal and ventral edges, and round the posterior end.

The branchial sac (PL IV. figs. 2-4) is very thick and solid looking, and the folds,
which converge towards the oesophageal aperture, are well marked. Those on the right
side have their oesophageal ends attached to the dorsal continuation of the endostvle
(PI. IV. fig. 4), while those on the left side join the posterior extremity of the dorsal lamina.

There are only six to ten large transverse vessels and they run obliquely, converging
towards the short dorsal lamina (PI. IV. fig. 2, tr.)\ The infundihula (PL IV. fig. 3) are
numerous, irregular, and shallow, and the stigmata vary greatly in length.

The endostyle is conspicuous and is very long, being continued round the posterior end
of the branchial sac and up the dorsal edge as far as the oesophageal aperture.

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

The dorsal lamina (PI. IV. fig. 4, d.l.) is short and broad ; the free edge is cremated,
hut a regular series of teeth is not present.

The tentacles are large and greatly branched, and their branchial surface, from which
the pinnae spring, is usually vesicular. The shape of one of the larger tentacles is irregularly
pyramidal with the apex generally curled upwards towards the branchial aperture, so that
the lovvrer side on which the branches are placed is convex (PI. IV. fig. 4, tn.) The base
is very thick, and is seen from sections to be highly muscular. Numerous bundles of
fibres, imbedded in the connective tissue and running in all directions and interlacing,
occupy a zone extending about half-way to the centre of the tentacle.

The peritubercular area is very small, and the dorsal tubercle extends across the
prsebranchial zone almost to the base of the tentacles (PI. IV. fig. 4).

The intestine is large and lies on the left side, occupying chiefly the dorsal edge
and posterior end. The oesophageal aperture (PI. IV. fig. 4, os.a.) is situated far forward
in the sac, generally between one-third and one-fourth of the distance from the anterior
to the posterior end. In a specimen 16 cm. in length and 7 '5 cm. in breadth the
dimensions of the branchial sac were as follows: —

From peripharyngeal band to posterior end, ... 8 cm.

From peripharyngeal band to oesophageal aperture, . . . 2 ,,

From peripharyngeal band to branchial aperture, . . . 4 „

Breadth of sac at level of oesophageal ajierture, . . . 4 ,,

Breadth of sac at broadest part, . . . . . 6 „

The oesophagus is short and wide, and runs directly posteriorly from the oesophageal
aperture to open into the large stomach lying on the left dorsal edge of the posterior
part of the branchial sac. The intestine issuing from the stomach soon reaches the
posterior end of the branchial sac, and after turning towards the ventral edge runs
anteriorly for a short distance, then curving dorsally and posteriorly it returns closely
pressed against its first part, so that no open loop is formed, and finally runs anteriorly
along the dorsal edge of the branchial sac, past the oesophageal aperture, and opens into
the relatively small cloaca! part of the peribranchial cavity.

There are two ovate genital glands imbedded in the mantle, one on each side. That
on the left side lies anteriorly to the intestine, and nearer the ventral than the dorsal edge.
The glaud on the right side is nearly in the centre, and lies anteriorly and ventrally to the
large curved renal sac.

This species was obtained by the " Nassau " at two localities — Gregory Bay and near
Cape Virgins. In the Liverpool Free Public Museum1 there are some small specimens,
which were dredged by Captain W. H. Cawne Warren, off the Patagonian Bank,
lat. 41° 30' S., long. 52° 0' W.; depth, 50 fathoms.

The Challenger specimens (nearly forty) were all dredged at Station 313, January

1 I am much indebted to Mr. T. J. Moore, the curator of this excellent museum, for his kindness in allowing
me to examine specimens of this and several other species of Ascidians in the collection under his care.

KKI'oltT ON Till: TUNICATA. 73

20, 1876; lat. 52' 20' S., long. G8° 0' W. ; depth, 55 fathoms; bottom temperature,
80-8 C. ; sandy bottom.

Molgula gregaria, Lesson (sp.) (PI. IV. figs. 5-8).

Cynfhia gregaria, Lesson, Centurie Zoologique, p. 157, pL 52, fig. 3. Paris, 1830.

Gynthia gregaria, E. 0. Cunningham, Notes on the Reptiles, &c, obtaimil .luring the voyage of

H.M.S. "Nassau," Trans. Linn. Soc, vol. xxvii. p. 488.
Molgula gregaria, Herdman, Preliminary Report, Proc. Roy. Soc. Etlin., 1880-81, p. 234.

External Appearance. — The body is almost spherical or sometimes ovate, and is slight I v
compressed laterally. The posterior end is large and rounded ; the anterior is somewhat
narrower and slightly projecting. The dorsal and ventral edges are strongly and equally
convex. It is attached by the posterior end of the left side.

The apertures are both at the anterior end, and are not distant ; the branchial is low,
hemispherical, and six-lobed ; the atrial is more prominent, narrower, and four-lobed.
The surface is smooth and glistening, slightly undulating and furrowed, and occasionally
a little wrinkled. The colour is white, with usually a hyaline blue tinge.

Length of the body, 7 cm. ; breadth of the body, 8 cm.

The Ted is cartilaginous and solid ; it is moderately thick and strong, and almost
opaque ; no vessels are visible.

The Mantle is thick, but not very muscular.

The Branchial Sac is strong, with seven distinct but narrow folds on each side.
The internal longitudinal bars are strong but few. The transverse vessels are very
irregular; they divide and anastomose to form a network in the meshes of which the
irregular and complicated infundibula are set. The stigmata are rather small, and they are
curved and arranged in spirals. Broad horizontal membranes attached to the internal
longitudinal bars run alone; the chief transverse vessels.

The Dorsal Lamina is rather thin, but broad ; it is crumpled, but neither ribbed nor
toothed.

The Tentacles are large and much branched; they are fourteen in number, and of
two sizes, placed large and small alternately.

The Dorsal Tubercle is elliptical or kidney-shaped ; both horns are much coiled, and
form large spirals ; the aperture is at the right side.

This species, like the last, was first described as a Cynthia. As no account of it has ever
been published except as to the external appearance, I have given here a full description
and figures.

The specimens differ somewhat in appearance on account of the condition of the
test. This seems to vary considerably, being in some individuals thin, except at the
posterior end, while in others it is much thicker, staffer, and more opaque (as in the
specimen figured, PI. IV. fig. 5). The lobes around the prominent apertures are very
distinct, and the branchial has, in addition to the six ordinary lobes, a series of six much

7 1 THE VOYAGE OF H.M.S. CHALLENGER.

smaller placed alternately with the larger ones (PL IV. fig. 5). In minute structure,
the test is very compact (PL IV. fig. 8), having a close homogeneous matrix (t.m.), in
which large fusiform and stellate distinctly nucleated protoplasts (t.c.) are scattered. In
i lie protoplasm of some of these, clear spaces or vacuoles are visible, and these seem in
process of becoming converted into bladder-cells, but no true bladder-cells and no pig-
ment-corpuscles were noticed.

The mantle is thick and dark coloured, but is not very muscular, the chief fibres
being a series of bands radiating from each aperture (PL IV. fig. 7, m.b.), and the
sphincters. There are also much finer irregular bundles of fibres all through the
mantle.

The branchial sac is peculiarly thick and opaque (PL IV. fig. 6). The network
formed by the transverse vessels is strong, and there are broad horizontal membranes
hanging from most of the transverse vessels and attached by their ends to the internal
longitudinal bars. The stigmata are small, as the interstigmatic tubes, like all the vessels
in this sac, are strong.

The dorsal tubercle is enclosed in a triangular peritubercular area, and has a reniform
shape with the greatest length antero-posterior. Both horns are coiled inwards and form
close spirals, the posterior being the larger.

The oesophageal aperture is a little more than one-third of the way down, and the
oesophagus curves ventrally and posteriorly. The stomach is not clearly defined, and the
intestine turns anteriorly and then dorsally for a short distance, then curves abruptly on
itself and returns on the anterior side of the former part, and, closely pressed to it, passes
the oesophagus and ends near the atrial aperture. The genital gland on the left side lies
in front of the intestine on the ventral side of the rectum. The gland on the left side
(PL IV. fig. 7, g.) lies near the dorsal margin in front of the large crescentic renal sac
(PL IV. fig. 7, r.o.), which contains, occupying its centre, a large pulpy elongated mass full
of black concretions.

Lesson's specimens were got at Port Louis, Falkland Islands. Cunningham obtained
his at Gregory Bay, in the Straits of Magellan, and at Stanley Harbour, Falkland Islands.

The Challenger brought home six specimens from the Falklands, at Station 315,
January 27, 187G; lat. 51° 40' S., long. 57° 50' W. ; depth, 5 to 12 fathoms; bottom,
sand and gravel.

Molgula peduneulata, Herdman (PL V. figs. 1-3).

Molgula peduncvlata, Herdman, Preliminary Eeport, Proc. Eoy. Soc. Edin., 1880-81, p. 234.

External Appearance. — The shape is between irregularly spherical and pyriform,
it is elongated transversely, and slightly compressed laterally ; the ventral edge forms
a short thick stalk while the rest of the body is globular. The anterior end is flat and
broad, and becomes continuous at its ventral edge with the short stalk. The dorsal edge

RETORT ON THE TUNICATA. 75

and the posterior end are strongly convex ; the body is attached by the extremity of the
produced ventral edge. The sides are slightly convex.

The apertures are both on the wide anterior end. They are sessile, and not con-
spicuous ; the branchial is at the ventral edge of the anterior end just above the stalk ;
it is indistinctly six-lobed, and directed anteriorly and slightly ventrally ; the atrial is
at the dorsal edge of the anterior end, it is distinctly four chft, and directed dorsally and
a little anteriorly.

The surface is even, but finely roughened all over with a minute granulation.

The colour is white with a hyaline tinge.

Length of the body (antero-posterior), 4 cm. ; breadth (dorso-ventral), 5 cm.

The Test is cartilaginous, thick and strong. It is smooth and glistening on the inner
surface. The texture is very compact, and no vessels are visible.

The Mantle is not very thick. The muscle bands are irregular, they are distinct but
distant. The branchial and atrial siphons are well developed.

The Branchial Sac is not thick, and has seven folds upon each side. The internal
longitudinal bars are strong ; there are usually about six on a fold, and several in the
space between two folds. The transverse vessels are variable, and sometimes irregular;
horizontal membranes are usually present. The stigmata are arranged in irregular
transverse rows, rarely in spirals.

2 he Dorsal Lamina is short, but very wide ; it is thin, and there are no ribs nor
marginal teeth.

The Tentacles are large, branched, about twelve in number, and of two sizes placed
larger and smaller alternately. One very large one occurs at the ventral edge, just anterior
to the extremity of the endostyle.

TJi e Dorsal Tubercle is situated a long way posterior to the tentacular circlet ; it is
equidistant from the branchial and atrial siphons, is somewhat reniform in outline, and
is elongated antero-posteriorly. The horns are simply turned in, not coiled ; the opening
is directed dorsally and to the left.

This species is very unlike a Molgula in external appearance, and would much more
readily be referred to the Cynthiidas at first glance, while in some respects it appears to
have affinities with Ascopera. The position of the stalk is peculiar (PI. V. fig. 1).
It is a prolongation of the ventral edge, and is more anterior than posterior ; hence, in
the natural position of the animal, the atrial aperture is higher and more prominent
than the branchial. There are no hair-like processes on the outer surface of the test,
and no incrusting sand, but the surface is finely granulated all over.

The mantle is not very muscular, the bundles being rather distant (PI. V. fig. 2).
There are circular bands on the prominent branchial and atrial siphons, from each of which
a series of radiating bundles issues. The edge of the branchial siphon is indistinctly
six-lobed, while the atrial is square (PI. V. fig. 2).

(ZOOL. CHALL. EXP. — PAET XVII. — 1882.) li 11

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

The branchial sac has the stigmata rather irregularly arranged (PI. V. fig. 3). In
some places they form transverse rows, while in others they run obliquely or in spirals.
The transverse vessels are often imperfect, but horizontal membranes are generally present,
and extremely delicate ones, running only for short distances, may be seen here and there
(PL V. fig. 3). This branchial sac in some of its features indicates an approach to the
Cynthiad type. The lips of the endostyle are prominent.

One of the larger tentacles, placed on the ventral edge of the circlet, greatly exceeds
the others in size. This disproportionate development of one of the tentacles is also
found in a species of Culeolus (C. wyviUe-thomsoni), but there it is the most dorsally
placed tentacle that is gigantic.

The great distance of the dorsal tubercle from the tentacular circlet is notable. It
lies immediately under the nerve ganglion, which is seen in PL V. fig. 2, at the base of
the atrial siphon.

One specimen of Molgvla pedunculata was obtained to the south of Kerguelen
Island, at Station 150, on February 2, 1874; lat. 52° 4' S., long. 71° 22' E. ; depth,
150 fathoms ; bot. temp. 1°"8 C. ; hard ground.

Molgula horrida, Herdman (PL V. figs. 4-7).

Molgula horrida, Herdman, Preliminary Report, Proe. Roy. Soc. Edin., 1880-81, p. 235.

External Appearance. — The body is rudely ovate, inclined towards quadrangular in
shape, and somewhat compressed laterally. The anterior end is wide, rather truncated,
and convex in its ventral part. The posterior end is wider than the anterior, it is convex
but flattened in the middle. The ventral edge is strongly convex, with a depression in
the middle of its length ; the dorsal is concavo-convex, going from the anterior to the
posterior end. The body is attached by the ventral part of the left side. The
apertures are both on the right side near the anterior end ; they are not distant, are
slightly projecting, and have the lobes irregular. The branchial is half-way from the
ventral edge to the centre ; the atrial is near the dorsal edge.

The surface is irregular and rough, and is almost entirely covered with sand and
adhering animals.

The colour, when the test is visible, is dull brown.

Length of the body, 5 cm. ; breadth of the body, 5 cm.

The Test is thick, solid, and very stiff. It is smooth and glistening on the inner
surface.

The Mantle is very thick but not muscular, the bands being very fine. The siphons
are wide, funnel-shaped, and distinctly lobed.

The Branchial Sac is very thick, is of a dark green colour, and has seven folds on
each side. The transverse vessels are irregular, in fact generally indeterminable, beino-

REPORT ON THE TUNICATA. 77

broken up into a system of branching : m « 1 anastomosing tuhes, which form the b:i
of the infundibula. Large square meshes are, however, marked out by the intersection
of wide horizontal membranes with the internal longitudinal bars, and each of these
meshes contains a number of infundibula. The internal longitudinal bars are prominent,
and are connected by wide horizontal membranes, from which, as well as from the bars,
other more delicate oblique membranes spring ; these run in all directions over the inner
face of the sac. The stigmata are long, coiled spirally, and crossed here and there by
delicate radiating tubes.

The Dorsal Lamina is short, and quite plain, with no ribs nor teeth.

The Tentacles are large and branched ; they are ten in number, with some additional
very small intermediate ones.

Tlie Dorsal Tubercle is prominent, and is elongated antero-posteriorly ; both horns
are much coded, forming large spirals.

This dark, rough, and irregular-looking species has a large part of the outer surface
covered with adhering sand, &c, but there are no hair-like processes upon the test.
Both apertures are rather irregular, but the four atrial lobes are tolerably well marked
(PI. V. fig. 4). The mantle, branchial sac, and tentacles are all of a dark green colour;
and the mantle and branchial sac are very thick and opaque. The siphons (PI. V. fig. 5)
are prominent and funnel-shaped, with their margins beautifully and distinctly lobed,
the branchial having six and the atrial four. The musculature is close but very fine,
and is quite different from the characteristic Molgulid arrangement. On the right
side the mantle as usual is thinner over the region of the renal organ, the outline of
which shows through (PI. V. fig. 5).

The figure of the branchial sac (PI. V. fig. 7), though correct as to the form and
position of the parts, does not represent well the depth of the infundibula and the
thickness of the sac. The interstigmatic vessels are delicate, and are coded spirally, the
different turns of the spiral being frequently connected by fine radiating tubes. Delicate
oblique membranes (PI. V. fig. 7, o.m.) are present in considerable number, running
irregularly over the inner face of the infundibula, and attached to the network formed
by the broken up transverse vessels.

The dorsal tubercle is large and prominent. It lies in a shallow triangular peri-
tubercular area (PI. V. fig. 6), but extends nearly up to the tentacular circlet.

The genital gland on the right side, placed anteriorly to the renal sac, is large and
flask-shaped, having a short wide duct attached at its upper end. The mouth of the
duct has its margin cut up into several long delicate finger-like processes.

Two specimens, adhering together, were obtained at the Falkland Islands from
Station 315, January 27, 1876 ; lat. 51° 40' S., long. 57° 50' W. ; depth, 5 to 12
fathoms ; sand and gravel.

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

Molgula forbesi, Herdnian (PL V. figs. 8-11).

Molgula forbesi, Herdnian, Preliminary Eeport, Proc. Roy. Soc. Edin., 1880-81, p. 23C.

External Appearance. — The body is globular in shape, slightly elongated dorso-
ventrally, and not compressed laterally. The anterior end is slightly projecting, narrow,
flattened, and has a siphon at each extremity. The posterior end is wide, and regularly
rounded. The dorsal and ventral edges are both extremely convex ; the body is not
attached. The apertures are both at the anterior end, they are not distant, but are slightly
prominent. The branchial is at the ventral edge of the anterior end, and is turned
ventrally; the atrial is at the dorsal edge, and points anteriorly, it is more prominent
than the branchial.

The surface is entirely covered with a close coating of sand grains. The colour is
dull brown (due to the sand).

Length of the body, l-8 cm. ; breadth of the body, 2 cm.

The Test is not thick but stiff ; it is quite opaque.

The Mantle is thin and transparent, the viscera being seen through distinctly. The
muscle bands are numerous, but very fine. There are a few stronger circular bands
round the short tubular siphons, and a series of longitudinal bundles radiate from the
base of each siphon.

TJie Branchial Sac is rather delicate, and has seven folds upon each side. The
transverse vessels vary greatly in calibre and position, and are often quite irregular.
The internal longitudinal bars are strong, and there are three or four on each fold. The
stigmata are very irregular, being straight, and arranged in transverse rows in some
places, while in others they are curved, and form spirals, or run irregularly. Delicate
horizontal membranes are frequently present, running from fold to fold. There are also
more irregular longitudinal and oblique membranes.

The Dorsal Lamina is a short and narrow membrane with a plain edge.

The Tentacles are compound, situated on a strong muscle band. There are about
twelve large and twelve small placed alternately.

The Dorsal Tubercle is simple, and placed at the posterior end of a deep and irregular
peritubercular area. The left side of the tubercle extends further anteriorly than the
right ; both horns are turned to the left.

I have dedicated this elegant little species to Professor Edward Forbes who founded
the genus Molgula. It has a globular shape (PI. V. fig. 8) with the apertures at the
anterior end, forming what are evidently permanent projections, since the sandy coating
extends over them up to the very edge of the apertures.

The mantle is very delicate and quite transparent, allowing the viscera to be seen
through distinctly (PI. V. fig. 9). The branchial sac is also delicate, and the folds

REPORT ON THE TUNICATA. 79

are slight, with generally three or four internal longitudinal bars upon each (PI. V. fig. 10).
Usually there are no bars on the spaces between the folds, but sometimes one may be
present. These spaces are, however, traversed by narrow membranes, horizontal, oblique,
and longitudinal — the horizontal ones (PI. V. fig. 10, h.m.) indicating the positions of the
irregular transverse vessels. The stigmata are in some places arranged in complicated
spirals, while in others they form more or less regular transverse rows (PI. V. fig. 10).

The dorsal tubercle (PL V. fig. 11) is much simpler than is usual in the genus. It is
not prominent, and the horns are not spirally coded, but merely turned posteriorly. The
peri tubercular area is large and irregularly triangular, the peripharyngeal bauds bounding
it laterally having an undulating course.

The intestine (PI. V. fig. 9) is long and narrow, and the loop turns anteriorly towards
the branchial aperture, so as to partially enclose the left genital gland.

One specimen was obtained at Port Jackson, Australia. Depth, 2 to 10 fathoms.

Molgula pyriformis, Herdman (PL VI. figs. 1-3).

Molguta pyriformis, Herdman, Preliminary Eeport, Proc. Boy. Soc. Edin., 1880-81, p. 236.

E.iitTnid Appearance. — The body is pyriform or almost triangular, and is compressed
laterally; it is not attached. The anterior end is wide, straight, truncated, and has an
aperture at each extremity ; the posterior is narrow and pointed. The dorsal and ventral
edges are both convex. The widest point is at about one-third of the length from the
anterior end, and from this point the two edges taper rapidly to the narrow posterior end.
The apertures are at the extremities of the flat anterior end, they scarcely project, and
are inconspicuous. The branchial is rather the more anterior of the two, and the more
prominent, and is directed ventrally ; the atrial is quite sessile, and points anteriorly.

The surface is entirely covered with a close coating of fine sand.

The colour is dark brown (due to the sand).

Length of the body, 2 cm. ; breadth of the body, I'.j cm.

The Test is thin but stiff, and quite opaque.

The Mantle is thin, with the musculature moderately developed. The strongest
bands are those that radiate from the bases of the branchial and atrial siphons. Over
the rest of the mantle the commonest form of muscle band is a short thick fusiform
clump of fibres.

The Branchial Sac is delicate, with seven folds on the right side and six on the left.
These folds do not include the stigniatic part of the branchial sac, but are merely formed of
two or three additional internal longitudinal bars united by short transverse ducts, and
thus forming an open network. There are no transverse vessels distinct from the fine
intcrstigmatic tubes, but narrow horizontal membranes are present running transversely
from fold to fold across the intervening space. The fine interstigmatic vessels are

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

arranged in rather distant and irregular longitudinal rows of spirals. The stigmata are
huge, they are curved in the spirals and more or less linear between. Delicate radiating
tubes are frequently present.

The Dorsal Lamina is a plain narrow membrane.

The Tentacles are branched, but not large ; they' are numerous and of many sizes,
arranged indefinitely.

The Dorsal Tubercle is very simple, and is tubular ; it has a wide funnel-shaped
aperture anteriorly, which rapidly narrows as it runs backwards and becomes lost in the
neural gland. The peritubercular area is large and triangular.

This species has a curious external form, the posterior end, contrary to the usual rule,
being narrow and pointed, while the anterior is broad and flat (PI. VI. fig. 1).

The mantle is not very muscular, and over the greater part of its area the fibres are
arranged, chiefly three to six or more together, in short fusiform clumps which taper
suddenly at the two extremities and end in long delicate filaments.

The chief characteristic feature in the branchial sac (PI. VI. fig. 2) is the structure of
the folds. These are very simple and consist merely of two or three additional internal
longitudinal bars attached to each normal one by short transverse ducts, like the
connecting ducts from the transverse vessels. These ducts are placed in the same line
with the horizontal membranes, and thus seem to indicate the position of the transverse
vessels (PI. VI. fig. 2, h.m.). In some of the folds there are twice as many ducts
between the second and third internal longitudinal bar as between the first and second,
so that if, for example, the first and second bars were connected by a transverse duct at
every millimetre the second and third bars would be connected by ducts at every
millimetre and every half millimetre.

There are seven folds on the right side of the sac and only six on the left, but, as
the collection contains only one specimen of the species, this may be an individual
abnormality. The stigmata are large and in some places are arranged in spirals, forming
shallow infundibula. Between the spirals the stigmata are generally linear, and form
irregular transverse rows. They are frecpiently crossed by narrow tubes (PI. VI. fig. 2).

The dorsal tubercle is extremely interesting. It is in the simplest possible form,
being merely the widened aperture of the duct from the neural gland. This duct may
be seen distinctly (PL VI. fig. 3) running anteriorly and swelling out to form the large
funnel-shaped aperture. It is placed near the anterior end of the large and deep
triangular peritubercular area, which extends so far posteriorly as to include in its area
the greater part of the neural mass (PL VI. fig. 3, n.).

A single specimen of this species wras dredged off the coast of Buenos Ayres, South
America, at Station 320; February 14, 1876 ; kit, 37° 17' S., long. 53° 52' W. ; depth,
600 fathoms ; bottom temperature, 2°'7 C. ; bottom, hard ground.

REPORT ON THE TUN 10 ATA. 81

Eugyra, Alder and Hancock'.

Cynthia, Midler, Index Moll Groenl. 1842. In part,

Eugyra, Aid. and Han., Hancock, On the larval state of Molgula, &c, Ann. and Mag. of Nat.

Hist., ser. iv., vol. vi. p. 353, 1870.
MiJguIa, KuplVer, .lalnvslier. der ( 'mumiss., &e. 1871. In part,
Eugyra, Lacaze-Duthiers, Los Ascidies Simples des cotes de France, Arch, de ZooL exp6r. et

gener., t. iv. p. 047. 1877.
Eugyra, Traustedt, Oversigt over de fra Danmark og dets nordlige Bilande Kjendte Ascidiaj

Simplices, Vidensk. Medd. Nat. Foren. i Kj0benhavn, 1879-80, p. 428.

Body globular, unattached. Branchial aperture six-lobed ; atrial four-lobed.

Test usually thin and transparent, incrusted with sand or plain.

Branchial Sac with no folds. Internal longitudinal liars few, but broad and

ribbon-like. Infundibula formed of regularly coiled vessels, which form a

double spiral meeting at the apex.
Tentacles compound.
Genitalia forming a single mass situated on the left side close to the intestine.

The above definition of the genus is that of Hancock, slightly modified so as to admit
a species such as Euyyra Irryuelruensis, which has no glandular hairs on the outer surface
of the test and is not incrusted with sand, and so as to be in accordance with the nomen-
clature of parts adopted in this work.

The main distinction between this genus and Molyula lies in the structure of the
branchial sac, Euyyra being characterised by the entire absence of folds, the broad
ribbon-bike internal longitudinal bars, and the large and regularly coiled infundibula.

Euyyra kerguelenensis, Herdman (PI. VI. figs. 4-9).

Eugyra licrgui'lma'ii.-i.-; Herdman, Preliminary Report, Proc. Roy. Soc. Edin., 18S0-81, p. 237.

External Appearance. — The body is globular or slightly elongated dorso-ventrally
and is not compressed laterally ; it is not attached. The anterior end is broad, convex, and
flattened in the centre between the two apertures ; the posterior end is more convex.
The dorsal and ventral edges are nearly equally rounded; the sides are convex. The
apertures are both at the anterior end, they are not distant, and are conspicuous ; the
branchial is sessile, or almost so; the atrial is much more prominent, forming a short
cylindrical projection pointing directly anteriorly.

The surface is even and smooth, with the exception of a few wrinkles round the
apertures. There is no sand adhering.

The colour is a light transparent grey.

Length, including the atrial siphon, 2 cm.; breadth, 1-8 cm.

The Test is very thin and transparent, except on the atrial siphon and immediately
around the branchial aperture where it is thicker.

S2 THE VOYAGE OF H.M.S. CHALLENGER.

The Mantle is thin and membranous, and the musculature is extremely feeble ; with the
exception of a few bands radiating from the apertures, there are almost no muscular fibres.

The Branchial Sac is strong, and not folded. The internal longitudinal bars are in
the form of broad ribbon-like bands. The transverse vessels are slight and irregular ;
narrow horizontal membranes are usually present. The infundibula are large, and are
usually square or pentagonal at the base. The fine interstigmatic vessels are narrow
and much coiled, the spiral having from ten to thirty turns (generally fifteen to twenty).
The radiating vessels are slight, a few short intermediate ones are frequently present.

The Dorsal Lamina is a plain broad membrane.

The Tentacles are branched and delicate ; they are numerous, about twelve large and
twelve smaller, and three orders of simple and very minute ones alternate regularly.

Tlie Dorsal Tubercle is simple, having an elongated oval cavity ending in a quad-
rangular aperture anteriorly. It is placed in a shallow triangular peritubercular area.

This is the fourth species of Eugyra known to science, the three others being Eugyra
glutinans, Moller ( = Eugyra arenosa, Alder), Eugyra pilularis, Verrill, and Eugyra
globosa, Hancock. The discovery, so far south as Kerguelen Island, of a member of this
genus, which has been hitherto found only in the northern hemisphere, is very
interesting.

This species, though having all the characters of Eugyra well marked, differs from the
three previously known species in many particulars. Perhaps the most notable difference
is in the external appearance, as Eugyra kerguelenensi-s has a debcate transparent test
with no adhering sand, and has the atrial aperture permanently projecting on a short
cylindrical siphon (PL VI. figs. 4 and 5). The specimen represented in figure 5 differs
considerably from what is probably the normal condition of the species as shown in
figure 4. In internal structure, however, they are identical, and undoubtedly belong to
the same species. Probably figure 5 is a somewhat abnormal specimen.

The mantle is remarkably thin, and, with the exception of the bands radiating from
the apertures, there are almost no muscles, only a few delicate fibres being placed at
considerable distances.

The shallow infundibula in the branchial sac (PI. VI. fig. 8) are large and have a great
number of coils in the spiral ; up to thirty have been found, but the usual number is
between fifteen and twenty (PI. VI. fig. 8). Besides the delicate radiating vessels which
extend from the angles into the centre of the infundibulum, there are usually present
some intermediate ones of shorter extent (PI. VI. fig. 8, r.v'.).

The tentacles are delicate but very numerous. There are five distinct sizes, the
two larger of which are always compound, and the three smaller usually simple (PL VI.
fig. 6). If we number them from A to E, according to their size, the arrangement will be
found to be as follows :— A, E, D, E, C, E, D, E, B, E, D, E, C, E, D, E, A (PL VI.

REPORT ON THE TUNICATA. 83

fig. G). The series A are by far the largest, and are usually much branched. The membrane
on their posterior (branchial) surface is loose and voluminous (PI. VI. fig. 7, tn. m.).

The dorsal tubercle (PI. VI. fig. 9) is very simple, and approaches in structure that
of Mohjiiht pyrifonnis (PI. VI. fig. 3). The duct from the neural gland swells out at
the posterior angle of the peritubercular area into an elongated oval chamber, which
opens anteriorly by a simple quadrangular mouth.

Three specimens of this species were obtained at Kerguelen Island. One is labelled
" Kerguelen, 10-60 fathoms;" one " January 29, 1874, off London River, Kerguelen,
100 fathoms; " and one " Kerguelen, 10-100 fathoms."

Family Cynthiid^;.

Body usually attached, rarely free, sometimes pedunculated.

Test membranous or coriaceous, rarely cartilaginous or covered with sand.

Branchial aperture four-lobed, atrial four-lobed.
Branchial Sac longitudinally folded ; internal longitudinal bars not papillated ;

stigmata straight, never formiug spirals.
Tentacles simple or compound.

Intestine on the left side, slightly or not at all attached to the mantle.
Genitalia on the inner surface of the mantle, either on both sides or on one only.

The Cynthiidse, and especially those forming the sub-families Bolteninse and
Cynthinas, which have compound tentacles, are not far removed from the Molgulidse, and
were only separated as a distinct family by Lacaze-Duthiers in 1877. Heller previously
(1874-77) considered them as one family. The Cynthiidae form a very large group, and
contain probably more known species than the other three families of Ascidias Simplices
put together.

Savigny, in 1816,1 founded two of the genera comprised in this family, namely Boltenia
and Cynthia. The latter genus as defined by Savigny may be split up into two well-
marked sections — one containing the typical forms (the modern Cynthia), in which there are
many folds in the branchial sac and the tentacles are compound ; and the other including
the Styela-like forms with only four folds on each side of the sac and simple tentacles.

As each of these three types has been split up into genera I have thought it best to
consider them as sub-families, and they were described in the Preliminary Eeport 2
as the Cynthime, the Bolteninas, and the Styelinse.

The condition of the apertures though rather variable is quite characteristic ; there are
never more than four well-marked lobes round either branchial or atrial apertures.

1 Mi imoires sur lea Animaux .sms Vertebres, pt 2, fasc. 1.

2 Proc. Roy. Soc. Edin., Session 1880-81, p. 53.

(ZOOL. CHALL. EXP. PART XVII. — 1882.) R 12

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

Usually both openings are either four-lobed or cross-slit — that is, the lobes are triangular,
and fit together so closely as to reduce the apertures to four narrow slits, radiating from
a point so as to form a cross (PI. XX. fig. 1). In the genus Culeolus (belonging to the
sub-family Bolteninaj), however, the apertures have each less than four lobes, the branchial
being triangular and the atrial bilabiate.

The shape of the body varies greatly, more than in any other family ; ranging from the
squat blister-like Styela grossularia to the long pedunculated Boltenia, and including a
number of irregular and curious forms such as the species of Microcosmus.

The condition of the test is also variable, and can hardly be said to characterise the
family. In the majority of the species, however, and in the most typical forms (those
belonging to the Cynthinse), the test is leathery, comparatively thin, but tough aud
roughened on the outer surface. In some species {e.g., Boltenia pachydermatina,
Culeolus ivyville-thomsoni, &c.) it is thick and cartilaginous, while in a few remaining cases
(e.g., Culeolus perlucidus) it is thin and membranous.

The mantle is very muscular in the majority of the Cynthiidse, and in its most highly
developed condition consists of three layers of muscle fibres — an outer longitudinal
and an inner longitudinal separated by a middle circular. In most cases, however, the
inner layer is absent, and there are only the two well-developed layers, the outer longi-
tudinal and the inner circular crossing at right angles.

In Culeolus murrayi and most of the other Bolteninse they do not form continuous
layers, consequently the musculature has the appearance of an open network formed
by the longitudinal and circular bundles of fibres.

In some Cynthiidse (e.g., Styela oblonga) the musculature is very feeble, and is re-
duced to a few faint longitudinal bundles, while in Styela flava (PI. XX. fig. 3) the
arrangement of the fibres appears to be quite irregular, and no trace of longitudinal and
circular layers can be made out.

The branchial sac has longitudinal folds, and in typical members of the sub-family
Cynthinse they are very large, and sometimes numerous (at least twenty -four in Cynthia
grandis according to Heller).1 In the Styelinaa the folds are reduced in number and
simplified. The typical number in this sub-family is eight, four on each side ; this number
is never exceeded, but is sometimes much reduced, as in Styela grossularia, van Beneden,
where there is only a single fold.

In Culeolus and Fungidus the whole sac is much simplified by the absence of the
system of fine longitudinal or interstigmatic vessels. In all the other Cynthiidse the
stigmata are straight, and are arranged in regular transverse rows.

The tentacles are compound in the sub-families Bolteninas and Cynthinse and resemble
those of the Molgulidse, but in the Styelinse they are simple and filiform as in the
Ascidiidse.

Beitrage zur nahern Kenntniss tier Tunicaten, p. 15, Sitzber. d. k. Akad. d. Wiss., Bd. lxxvii., Abth. 1, 1878.

REPORT ON THE TUXICATA.

85

The chief differences between the sub-families may be shown in a tabular form thus

Cyntjiiih.k.

Branchial sac having more than four folds on

each side — Tentacles compound.

Branchial sac having four of less than four folds on
each side — Tentacles simple.

Body sessile or almost so.
I

CYNTHIN.E.

Body borne on a long peduncle.
I

BoLTENIN^E.

StYELIXjE.

Sub-Family Boltenin^e.

Body attached and pedunculated ; branchial and atrial apertures having either

four or less than four lobes.
Test coriaceous, membranous, or cartilaginous, not covered with sand.
Bra nch kd Sue with more than four folds on each side.
Tentacles compound.

This sub-family was formed1 for the reception of Boltcnia, Savigny, Cystingia,1
Macleay, and the new genera Culeolus and Fungulus, discovered by the Challenger
Expedition. It is more nearly allied to the Cynthinas than to the Styelinse, as it agrees
with the former group in having compound tentacles, and more than four folds on each
side of the branchial sac. The Bolteninse are distinguished from the Cynthinse by the
long peduncle upon which the body is borne.

The genera in the sub-family may be arranged in a tabular form as follows : —

BoLTEXIX.E.

Fine longitudinal vessels and stigmata
present in the branchial sac.

I
Boltenia.

No fine longitudinal vessels in the
branchial sac.

Branchial aperture fourdobed.

I
Cy&Hngia.

Branchial aperture more or
less triaugular.

Stalk relatively
short and thick.

I
/ gulw.

Stalk relatively
long and thin.

I
Cuh'ohis.

1 Preliminary Report, part hi., Proc. Roy. Soc. Edin., 1880-81, p. 53.

- This form, described by Macleay in 1823, was brought from the arctic Beaa, and, so far as lam aware, it has ii"t been
found since. From Macleay's description it evidently belongs to the Moltriiimr, and is closely allied to Boltenia. The
branchial aperture is described as four-lobed, and the atrial as irregular. The branchial sac is folded, and is stated to
have no branchial network ; possibly it is like that of Culeolus (see below, p. 90).

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

Bo? tenia, Savigny.

Yorticella, Linnaeus, Mant. Plant., p. 552. 1771. In part.

Ascidia, Miiller, Prod. Zool. Dan. 1776. In part.

Boltenia, Savigny, M£m. surles Anim. sans Vert., pt. ii. fasc. 1. 1816.

Body more or less globular, fixed on a long peduncle; apertures lateral, four-lobed.

Test coriaceous or cartilaginous.

Branchial Sac longitudinally folded, with six or more folds on each side. Fine

longitudinal vessels present, forming straight stigmata.
Tentacles compound.

This genus was founded by Savigny,1 in 1816, for the reception of pedunculated
Simple Ascidians with a coriaceous test. At that time it contained the species described
long before by Bolten (1770), but not named till the following year by Linnaeus, and a
new species Boltenia ovifera, Savigny.

Other species have been added to the genus since by Agassiz, Stimpson, Heller, and
others, and finally two new species have been discovered by the Challenger expedition.

Boltenia elegans, Herdman (PL VII. figs. 1-5).

Boltenia elegans, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 80.

External Appearance.— The, body has a quadrangular ovate shape, and is not
flattened laterally ; the anterior and posterior ends are bluntly rounded, and the dorsal
and ventral edges are nearly straight ; behind the atrial aperture the dorsal edge sinks
in somewhat towards the posterior end. The peduncle is long and thin, wiry, attached
to the ventral edge of the anterior end, and turned slightly ventrally. The apertures are
conspicuous ; the branchial is at the dorsal edge of the anterior end, directed anteriorly
and dorsally; the atrial is on the dorsal edge, two-thirds of the way down, and directed
dorsally and posteriorly.

The surface is smooth and glistening, but marked by a few creases. The colour of
the body is white, with a satiny lustre ; of the stalk light yellowish brown.

Length of body, 5.5 cm. ; breadth of body, 4 cm. Length of stalk, 36 cm. ; thick-
ness of stalk, 2 mm.

The Test is thin but tough.

TJie Mantle is strong, and the musculature regular.

The Branchial Sac has nine folds on each side, those next the endostyle being closer
than the dorsal ones. The transverse vessels are wide and distant. The internal
longitudinal bars are narrow but well marked, and run at right angles to the stigmata,
which are transverse, lying between narrow longitudinal bars which connect the transverse
vessels. The stigmata are rather long and narrow, there are about fifteen in each mesh.

1 Mem. sur les Anim. sans Vert., 2e pt. le fasc. p. 87.

REPORT ON THE TUNICATA. 87

Tlie Dorsal Lamina is represented by a scries of closely placed, large, tapering languets.

The Tentacles arc large, and branched ; they are sixteen in number, placed long and
short alternately.

The Dorsal Tubercleis large and distinct, elongated transversely but directed verti-
cally, the opening being on the right side ; both horns are coiled inwards.

This species seems at first sight very like Savigny's Boltenia ovifera, but they differ
in many particulars. The resemblance is chiefly in the external appearance (PI. VII.
fig. 1), but the surface and colour are different, Boltenia ovifera being rougher and darker.
There is a species of Boltenia in the British Museum collection, unnamed but labelled
" from Australia," which is also very similar to Boltenia elegans, and may possibly be the
same species.

The test is thin and allows the direction of the chief bundles of muscular fibres to be
seen through it in places. The muscle bands of the mantle are strong but do not form a
continuous layer. There are a number of distant parallel bands running down the long
axis of the body, and intersecting two series of bundles radiating from the apertures, so as
to form roughly quadrangular meshes (PI. VII. figs. 1 and 5, m. b.).

The branchial sac is remarkable, and has eighteen folds, nine on each side. Those
next the endostyle are more closely placed and smaller than the dorsal ones. The trans-
verse vessels are wide and distant, and the narrow internal longitudinal bars run at right
angles to them so as to form the usual series of meshes (PI. VII. fig. 2, tr. and LI.). The
fine longitudinal or interstigmatic vessels, however, run transversely in place of antero-
posteriorly, and as a result the stigmata are directed transversely, and cross behind
the internal longitudinal bars in place of running parallel to them (PI. VII. fig. 2, I. v.).
The languets and tentacles show nothing noteworthy.

The dorsal tubercle is large and has both horns coiled inwards (PI. VII. fig. 3, d. t.).
It lies in a moderately deep, triangular, unsymmetrically-shaped peritubercular area.

The intestine lies upon the left side of the branchial sac, and is seen in Plate VII.
fig. 4. The oesophageal aperture (03. a.) is placed far back in the sac, and the canal lead-
ing from it — there is no distinct stomach — runs along the ventral edge of the left side
till it reaches the anterior end of the body, where it sweeps round dorsally, and makes
two or three zig-zags along the dorsal edge(t.), so as to reach the posterior end where the
anus (a.) is placed. This is a wide aperture with a beautifully fringed margin ; it is close
to the atrial aperture, and points posteriorly and dorsally.

The genital masses are present on both sides (PI. VII. figs. 4 and 5) in the form
of elongated many lobed slightly branched organs directed antero-posteriorly, and termi-
nating close to the atrial aperture in a short genital duct (PI. VII. figs. 4 and 5, o. d.).
The left genital mass is rather the larger of the two, and lies chiefly in the intestiml
loop.

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

Two specimens (one somewhat damaged) were obtained south of Halifax, Nova
Scotia, at Station 48 ; May 8, 1873 ; lat. 43° 2' N., long. 64° 2' W. ; depth, 51 fathoms ;
hard bottom.

Boltenia legumen, Lesson.

Bohemia legumen, Lesson, Centime Zoologique, p. 149, pi. liii. fig. 1 (1830).

Boltenia coarcta, Gould, A. A., Mollusca, U. S. Explor. Exped. under C. Wilkes. Boston, 1852.

(?) Boltenia legumen, Cunningham, the Nat. Hist, of the Straits of Magellan, Edin., 1871,

pp. Ill and 263, and Notes on Eeptiles, &c, obtained during the voyage of H.M.S

"Nassau," Trans. Linn. Soc., vol. xxvii. p. 489.
Boltenia legumen, Herdman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1880-81, p. 81.

The Boltenia coarcta of Gould is evidently the same species as Boltenia legumen, which
is figured by Lesson, and is an easily recognised species. Cunningham's figure (Straits of
Magellan) shows rather a different outline, but it is probably the same species. The Chal-
lenger specimens are of various sizes, ranging from 1*3 cm. to 7 cm. in length, and from 1'2
cm. to 3 "5 cm. in breadth. The shape of the body is ovate or ellipsoidal, and it is fixed by
a short, sometimes twisted peduncle attached to the ventral edge of the posterior end of the
body, and running downwards at right angles to the ventral edge, so that the body is
supported with the dorsal surface upwards, and the anterior and posterior ends on the
same horizontal plane.

The apertures are both on the upper surface, but rather far apart, the branchial being
near the anterior end, and the atrial far back. Both are four-cleft, sessde, and very incon-
spicuous. The surface is very rough and covered with short bristle-like spines or hairs
which are sometimes branched. The specimen from Station 312 might be considered as
an echinated variety, as it has a dense coating of spines, which are usually much branched
and serrated. The colour varies from yellowish-brown through various ruddy shades to a
dark earthy brown.

The test is thin but very tough and leathery. The inner surface is pale coloured.

The mantle is moderately strong.

The branchial sac has seven folds on each side. The internal longitudinal bars are
strong and numerous ; there are about eight on a fold and the same number in the inter-
space, where the meshes are elongated transversely and contain each about ten stigmata.

The dorsal lamina is of no great breadth, but rather thick, so as to present the form of
a triangle in section. The edges are uneven but not toothed, and ribs are present along
the sides.

The tentacles are branched and of different sizes. There are twelve or fourteen, large
and small alternately, with very minute ones placed here and there at the bases of the
larger ones.

The dorsal tubercle, which lies in a small triangular peritubercular area, is large and
prominent, and has a circular outline. The aperture is small and is directed forwards.
Both horns are coiled inwards. The intestine forms a narrow loop.

REPORT ON THE TUNICATA. 89

The British Museum collection contains specimens of this species from "Philip Bay,"
"Falkland Islands," " Antarctic Seas," " Off Dungeness," '' Mouth of Peckett Harbour,"
and " Possession Bay."

The Challenger specimens are all from the Straits of Magellan and the neighbourhood
of the Falkland Islands, as follows : —

One specimen from Station 312, January 13, 1876; lat. 53° 38' S., long. 70° 56'
W. ; depth, 10-15 fathoms; bottom, mud. Eight specimens from Station 315, January
26, 27, 28, 1S76 ; lat. 51° 40' S., long, 57° 50' W. ; depth, 5-12 fathoms; bottom, sand
and gravel. One specimen from Station 316, February 3, 1876 ; lat. 51° 32' S., long.
58° 6' W. ; depth, 4-5 fathoms ; bottom, mud.

Boltenia pachydermatina, Herdman (PI. VII. figs. 6-8).

Bui tenia pachydermatina, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 81.

External Appearance. — The body is between ovate and fusiform in shape, and is
compressed laterally. The posterior (upper) end is bluntly pointed ; the anterior end is
narrow, becoming gradually continuous with the stalk ; the dorsal edge is more convex
than the ventral. The stalk is long, thick, twisted and creased, and rather tapering
downwards towards the point of attachment. The apertures are conspicuous but not
prominent, and not distant, being placed at the points of junction of the middle with
respectively the anterior and posterior thirds of the body.

The surface of the body is smooth but deeply grooved longitudinally ; the stalk is
closely wrinkled transversely.

The colour of the body is dull creamy white ; of the stalk, yellowish-brown.

Length of the body, 10 cm. ; breadth, 5 cm. ; length of the stalk, about 20 cm.

Tit e Test is very thick, tough, and stiff, between cartilaginous and coriaceous in
texture ; it is white and glistening on the inner surface.

TJie Mantle is thin but muscular, and adheres slightly to the test.

The Branchial Sac has about six folds on each side. The internal longitudinal bars are
numerous, about eight on the folds and six in the interspaces. The meshes are transversely
elongated, and contain each about nine stigmata ; they are always divided by a narrow bar.

Tfie Tentacles are compound, and densely branched. They are sixteen in number,
and of two sizes, placed large and small alternately. One of the tentacles is much larger
than any of the others.

Tlie Dorsal Tubercle is large, and circular in outline; the surface is marked with a close
and elaborate pattern.

This large and striking species, although apparently common and well known, has, so
far as I can ascertain, never been described or named. There are some very good
specimens of it in the British Museum collection, labelled as follows : — New Zealand
(about six specimens), Van Diemen's Land (about six specimens), Godthaal, Danish

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

Greenland, 80 fathoms (one specimen, labelled Boltenia clavata), New Zealand (about six
specimens, labelled Boltenia pedunculated, M. Edw.), and some others with no locality
marked. There are also some specimens in the Liverpool Free Public Museum, from
Port Chalmers, Dunedin, New Zealand. They were brought home by Dr. Millen
Cough trey, and are labelled Boltenia pedunculate/,.

In external form this species is rather like Boltenia bolteni, Linn., but they differ in
many detads of structure. The above description is taken from the large specimen. The
smaller one, which is figured (PI. VII. fig. 6), differs sbghtly in external appearance in
several respects, and has the test prolonged into a few short pointed processes scattered
here and there over the sides and posterior end, which gives it somewhat the appearance
of Boltenia gibbosa, Heller, quite a distinct species.

One of the most characteristic points in this species is the enormously thick test, of a
solid cartilaginous consistency, which suggested the specific name.

The dorsal tubercle is very peculiar. It is large and circular in outline (PI. VII. fig. 8),
while the surface is marked by a number of branched ridges forming an elaborate pattern.

Two specimens (one large and one small) were obtained from Canterbury, New
Zealand. They were presented to the expedition whde at Wellington.

Culeolus, Herdman.
Culeolus, Herdman, Prelim. Rep., Proc. Roy. Soe. Edin., 1880-81, p. 82.

Body fixed, pedunculated, more or less ovate ; the anterior end, where the long
peduncle is attached, narrower than the posterior. Branchial aperture more
or less triangular. Atrial aperture bilabiate.

Test cartilaginous, often very thin, usually rough and papillated on the outer surface.

Mantle thin ; musculature not greatly developed.

Branchial Sac with about six longitudinal folds on each side ; consisting of trans-
verse vessels and internal longitudinal bars forming a wide meshed network ;
there are no stigmata, the fine longitudinal vessels being absent. The larger
vessels, especially the internal longitudinal bars, are supported by a system
of branched calcareous spicules.

Endostyle also strengthened by numerous branched calcareous spicules.

Dorsal Lamina represented by a series of triangular languets.

Tentacles compound.

Alimentary Canal relatively small, placed posteriorly on the left side ; stomach ven-
tral, intestine turned anteriorly and dorsally, and rectum running posteriorly.

Genitalia on the inner face of the wall of the peribranchial cavity, developed on
both sides of the body.

As Culeolus is one of the most interesting of the new genera which were collected
during the Challenger expedition, I have gone more than usual into detail in the

REPORT ON THE TUNTCATA. !»1

following account. A short generic diagnosis, and a description of the six species for
the reception of which the genus was formed, were given in the third part1 of my Pre-
liminary Report on the collection. The morphological peculiarities, however, were
merely referred to ; while histological details, and remarks on the structural characteristics
and tluir hearing on our knowledge of the other members of the group, were omitted as
being out of place in a Preliminary Report intended merely to supply a short description
of the new species.

The genus Culeolus contains six species of Simple Ascidians, which in the first rough
classification of the collection were arranged in the genus Boltenia on account of their
long peduncles. A short examination, however, of their details of structure sufficed to
show that they could not be referred to that or any other known genus. Further invest i-
gation revealed several peculiarities common to the species, such as the structure of the
branchial sac, in which they differed from all previously known Simple Ascidians ;
it likewise showed that, although well-marked specific differences were present, and
characteristics might be taken from almost every organ, the six species were closely allied,
and possessed common characters, which rendered their union under one generic title
necessary.

The species may be distinguished by means of external characters alone, as shown in
the following table : —

Culcohis.
I

Peduncle turned posteriorly. Peduncle turned anteriorly.

Dorsal end fringed with papillae. Dorsal end not fringed. Dorsal end fringed with papilke. Dorsal end not fringed.

I I I I

C. recumbens. C. perlucidus. | I

Surface even. Surface very uneven. Surface even. Surface very uneven,

ft perlatus. C. murrayi. C. mosdeyi. C. wyvillc-thomsoni.

Of three of the species — Culeolus wyville-thomsoni, Culeolus perlatus, and Culeolus
moseleyi — only a single specimen was obtained, consequently in these the examination was
limited to those points which were necessary for a diagnosis of the species, and the
description below contains in addition only such observations as could be made without
further injuring the unique specimens. The other three species, each of which is repre-
sented by more than one specimen, will be described more in detail, commencing with
Culeolus murrayi, which may be taken as the type of the genus.

Culeolus murrayi, Herdman (PI. VIII. and PI. IX.).

Culeolm murrayi, Herdman, Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 83.
External Appearance. — Like the other species of the genus it consists of two parts, a
more or less oval " body " borne on the summit of a long thin " peduncle " (PI. VIII. fig. 1).

1 Proc. Roy. Sue. Edin., 18S0-S1, p. 82.
(ZOOL. CII.U.L. EXP. — PART XVII.— 1 882.) R 13

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

The shape of the body is irregularly pyriform ; it is not compressed laterally. The
anterior end is narrow, and tapers into the upper end of the peduncle. The posterior
end, on the contrary, is broad and bluntly rounded. The dorsal and ventral edges are
irregular ; they are, roughly speaking, parallel in their posterior two-thirds, and converge
rapidly in their anterior third. The sides are equally convex, the body in transverse
section being nearly circular.

The peduncle is of moderate length, thin but wiry, stiff but flexible, slightly undulating,
though straight in its general course. It is a prolongation of the anterior end of the
body, but at the point of junction turns dorsally at a right angle, so as to cross the
branchial aperture ; it is slightly enlarged at the upper and lower extremities, and else-
where it is of uniform thickness.

The branchial aperture is placed close to the anterior extremity on its dorsal edge,
consequently it is just under the peduncle (PL VIIL fig. 1). It is sessile but con-
spicuous, rather large and open, and triangular in shape — the base being anterior and the
apex posterior. It is surrounded by a broad fringe of close-set minute papillse or
processes of the test, and is directed anteriorly and dorsally. The atrial aperture is distant
from the branchial, being placed on the broad posterior extremity, a little to the dorsal side
of the middle, and directed posteriorly. Like the branchial aperture it is sessile and large.
It is bilabiate, in the form of a wide transverse slit, and is bordered by minute papilli-
form processes of the test.

The surface, which is rather irregular, being thrown into creases here and there,
especially towards the posterior end, is finely granulated all over, while larger projec-
tions form thickened borders to the apertures, and are especially developed along a line
encircling the body towards the posterior extremity. This line runs in an irregular
undulating course round the posterior end, and thus surrounds the atrial aperture (PI.
VIIL fig. 1). It reaches the posterior end of the ventral edge, but dorsally it extends
more anteriorly, so as to cut the dorsal edge about two-fifths of the way from the
atrial to the branchial aperture. Where it crosses the ventral edge it is enlarged into a
thickened mass of triangular shape, having the apex directed anteriorly ; while in the
dorsal region the belt narrows considerably, and the papilla? are of smaller size. The
surface of the peduncle is nearly smooth, slightly ridged longitudinally in parts.

The colour of the body is a dull brown with a slate-grey tinge where the surface is
least rough. The peduncle is of a pale slate-grey throughout.

The dimensions in the two specimens are as follows : —

A.

B.

Length of the body (anteroposterior),

6 cm.

5 cm.

Breadth of the body (dorso-ventral),

4-5 „

3-2 „

Thickness of the body (lateral),

4 „

3-4 „

Length of the peduncle,

15 „

9 „

Thickness of the peduncle, .

2 mm.

2 mm

REPORT ON THE TTJNTCATA. 93

Tlie Test is moderately thick and strong, but quite soft and flexible Its outer
surface is rough on account of the presence of small processes scattered thickly all over,
and developed in certain places into papilla-like tufts. These processes are of a brownish
colour, while the test at their base has a slightly grey tint ; where the processes are few or
of small size this slate colour shows, elsewhere the general appearance is brown. The
test is quite opaque.

On the inner surface, when the adhering mantle has been removed, the test has a pale
hyaline blue tint, with minute dots or punctures all over it. Under a low power of the
microscope (50 diameters) this appearance is seen to be caused by the presence of a large
number of small chambers deeply imbedded in the test (as viewed from the inner surface).
These are all very nearly of the same size, and are so numerous that the bars left between
them seem to mark out the entire surface into polygonal areas. Most of these chambers
in this view are seen to be occupied by masses of reddish-brown blood-corpuscles.

In thin sections through the test the minute papillae on the outer surface are seen to
be hollow (PI. VIII. fig. 2, t.p.), and their large bases contain the chambers seen from the
inner surface. These chambers or interior spaces of the papillae extend, however, a little
into the thickness of the test ; they are in direct connection with the blood-vessels
ramifying through the substance of the test, and frequently in sections one of the
terminal twigs of the vessels is seen entering the base of a chamber (PI. VIII. fig.
2, t.k.'). The vessels in this test seem rather feebly developed. They are not present in
large numbers in any of the sections, and they are of small size. These chambers
occupying the papillae seem to be a modification of the knobs on the ends of the terminal
twigs of the vessels so well developed in many species of the genus Ascidia, and like
them are generally filled with blood-corpuscles. Lacaze-Duthiers states1 that the hairs on
the test in the Molgulidas are merely the terminal knobs greatly developed in length.
In the present case we have them extending beyond the surface of the test as a series of
hernia-like papilla). The larger projections, however, found round the branchial and
atrial apertures, and on the belt round the posterior end, are comparable with the hairs
of the Molgulidtu, although their function appears to be different, as I have never
observed any foreign matter adhering to these processes. They are conical in shape,
taper to a blunt point, and have usually a considerable number of short lateral
branches which frequently bifurcate at the tip, and in some cases end in a clump com-
posed of several little papillae (PI. IX. fig. 3, t.k/). The whole process is hollow and
very thin-walled. It is, like the chambers at the bases of the smaller papillae,
directly continuous with the blood-vessels of the test, and usually contains blood-
corpuscles.

It is difficult to say what the use of these processes of the test can lie. Their
connection with the vascular system and their thin walls suggest a respiratory function,
1 Archives de Zoologie exp^rinnntak' et gi m rale, vol. iii. p. 314 (1874).

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

and, considering that the vessels of the test are by no means greatly developed, it would
be of great advantage probably that the blood circulating in the test should undergo
additional oxygenation.

The inner surface of the test is lined by a continuous layer of squamous epithelium.
The cells are large, regular, and distinctly nucleated ; they vary in shape from hexa-
gonal to diamond-shaped, and are usually broadly fusiform.

The remainder of the test is composed of an apparently structureless mass (PL VIII.
fio\ 2, t.m.), like the matrix of hyaline cartilage, in which are imbedded minute, circular,
fusiform, and stellate cells. A very delicate fibrillation may be detected here and there
in the matrix, but as a rule it has a homogeneous appearance. The cells are very
minute, and usually only the nucleus is visible. Often, however, a thin layer of proto-
plasm surrounding it can be made out, and from this delicate processes are occasionally
seen radiating outwards so as to give the cell a stellate appearance. No large bladder
cells nor pigment cells are present.

The blood-vessels in the test, and their large terminal dilatations in its outer layer
are lined by a layer of squamous epithelium of extreme delicacy. The nuclei of the cells
are always visible as a series of equidistant strongly refracting circular spots, dotting th>
walls of the vessels. In good specimens, however, the outlines of the cells are also
distinctly seen. The cells are large, pretty equal in size, but irregular in shape ; they
are scale-like, usually polygonal, and have sometimes undulating edges. The nuclei are
large, very distinct, circular in outline, and placed in the centres of the cells.

The peduncle is merely a prolongation of the test, and consists of the same structures
somewhat modified so as to produce the necessary toughness and rigidity. In transverse
sections under a low power (PI. IX. fig. 1), one sees that the peduncle is not a solid
mass, but is perforated by large canals, which show as more or less circular spaces in each
of which one or more blood-vessels are situated. In longitudinal sections (PI. IX. fig. 2),
it is seen that these canals are not parallel tubes, but are irregular, branching, anasto-
mosing, and of very different lengths, so that in fact they are merely a network of canals,
most of which run longitudinally. Up the centre of the peduncle, however, runs a
tube which is larger than the others, and appears to be continuous, aud of much
the same calibre throughout (PI. IX. fig. l). It communicates freely with the other
canals by lateral branches.

The test substance in which these canals are excavated presents two different
modifications. Round each canal, and round the outside of the peduncle is a layer of
hyaline semi-transparent substance (PI. IX. figs. 1 and 2, t.m.) like the compact part of
the normal test covering the body. The matrix is compact, stains faintly pink with
picro-carmine, and is apparently structureless, except in the immediate neighbourhood of
the modified tissue, where it is fibrillated. It contains numerous protoplasts which are
very minute, but distinctly nucleated. These are stained yellow by picro-carmine.

REPORT ON THE TUNICATA. 95

Outside this normal test substance, and therefore winding between the canals, air
masses and trabecule of a bright yellow-brown tissue (PI. IX. figs. 1 ami 2, t.m.v.) con-
centrically laminated — appearing as longitudinal striatum in longitudinal sections of the
bars. An examination of this tissue shows that it is merely a modification of the
neighbouring test substance caused by some sort of cornification taking place in successive
layers so as to produce the concentric lamination. The bright yellowish-brown matrix is
closely nbrillated, the bundles of fibrillar running as a rule parallel to the concentric
laminae. In this fibrous matrix numerous protoplasts are imbedded; they are very
minute, circular to fusiform in outline, and have comparatively large, brightly refracting,
circular nuclei.

The blood-vessels occupying the canals (PI. IX. fig. 1, ped. c.) and surrounded by the
unmodified test substance are of various sizes. A large trunk, and occasionally one or
more small branches from it, are found in the central large canal, while smaller vessels
occupy the other spaces ; like the canals they lie in, these vessels intercommunicate —
they form a branching and anastomosing system. The wall of all these vessels consists
of a single layer of cells. These are large and elongated, varying in shape from fusiform
to oblong, and have large and distinct circular and centrally placed nuclei, and finely
granular protoplasm. They lie with their long axes parallel to the length of the vessel,
and in transverse sections appear as small round cells.

TJie Mantle is thin but moderately strong ; it still (in spirit specimens) adheres to
the inner surface of the test, but the connection is slight, as it may be peeled off with
ease. The muscle bands are strong but distantly placed, so as to form an open network.
Most of the bands run transversely to the longitudinal axis drawn through the point of
attachment to the peduncle and the opposite extremity of the body, but a few longitudinal
bands are also present, radiating from the branchial and atrial apertures ; these lie
internally to the transverse muscles. On the branchial and atrial siphons the muscle
bands lie transversely, are more regular and parallel than elsewhere, and considerably
closer ; these can hardly be characterised, however, as sphincter muscles.

The muscle bands are flattened like ribbons, and contain on an average about fifty
fibres in their breadth. The fibres are rather large, of a much elongated fusiform shape,
and are closely packed in bundles. They stain deeply with carmine, but no distinct
nuclei are visible. In teased bundles, however, some rather smaller fibres (or series of
fibres) were noticed having swellings at intervals, or shaped like a series of spindles
joined by their ends ; these had distinct circular nuclei in the wider parts. No transverse
stripes were observed in any of the fibres.

The greater part of the mantle is composed of connective tissue, which envelopes and
stretches between the muscle bands. It is in the form of a thin layer of gelatigenous
areolar connective tissue — -a delicate transparent matrix, in many places apparently
structureless, in others finely fibrillated, and sometimes formed of bundles of white

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

fibrous tissue, penetrated by numerous branching anastomosing spaces (the "palli;il
capillaries " of some authors), and containing round, oval, fusiform, and stellate connective
tissue corpuscles.

The inner surface of the mantle is lined by a continuous layer of tesselated epithelium

—the " parietal layer of the atrial membrane " of Huxley, and the " lining membrane "

of Hancock. The cells are squamous, polygonal in outline, and rather large. The nuclei

are comparatively small, circular, central in position, strongly refracting, and stain deeply

with carmine.

The Branchial Sac is the most characteristic feature of the genus, and presents
striking peculiarities. In the present species it is of considerable size, occupying the
whole of one side of the body of the animal. To the naked eye it presents the apjaearance
of a coarse network, the meshes being very large and the vessels of considerable calibre.

A closer examination shows that, as in all the Cynthiidae, the sac presents certain
folds running longitudinally (or from the branchial to the oesophageal aperture) and
projecting from its internal surface. These folds are twelve in number, six on each
side of the sac. They are of moderate size, not very prominent, but still distinctly
visible. Those nearest to the dorsal edge of the sac are more distinct, and are more
closely placed than those towards the ventral edge, the pan- next the endostyle being
very slight.

The structure of this branchial sac is simple in the extreme (PL VIII. fig. 3).
There are two series of vessels — the transverse and the internal longitudinal bars. If
the branchial aperture be placed superiorly the transverse vessels will be found running
round the sac externally like a series of horizontally placed hoops, while the internal
longitudinal bars lie in a plane internal to the transverse vessels, and run down the
inner surface of the sac from the anterior to the posterior end. The two series of vessels
thus cross at right angles and foim a network with rectangular meshes. At their j)oints
of intersection — the angles of the meshes — the vessels intercommunicate.

The transverse vessels (PI. VIII. fig. 3, tr. and trf) are of two kinds, larger and
smaller ; they are placed alternately, and the larger vessels are about three times as wide
as the smaller ones. The meshes formed by the intersecting transverse and internal longi-
tudinal vessels are oblong, and have their greater extent antero-posteriorly or at right
angles to the transverse vessels. Over the greater part of the branchial sac, the propor-
tion between the sides of the mesh varies from 3 : 4 to 3:6 and is in most cases about
3:5, so that the transverse vessels are placed from once and a-half to twice as far from
one another as the internal longitudinal bars are. On the folds, however, the meshes are
much more elongated, in consequence of the comparative crowding together of the internal
longitudinal bars on these parts, while the transverse vessels are at the same distances as
in other regions of the sac.

The folds (PI. VIII. fig. 3, br.f.) are merely longitudinal tracts along which the

REPORT ON THE TUNICATA. 97

sac bulges to a greater or Less extenl into the interior of the cavity, so as to increase the
area of the wall, and along which the internal longitudinal bars are present in greater
number, and are therefore more closely placed than in other parts of the sac (PI. VIII.
fig. 3). In an average sixe of fold there are ten internal longitudinal bars, counting both
sides of the fold, while, in the plain space between two folds, there an- only four internal
longitudinal bars. Yet that open space is nearly as wide as the fold would be if spread out,
that is to say, it is nearly twice as wide as the fold in its normal doubled-up condition.
In fact, on an average, the internal longitudinal bars are about twice as closely placed
on the folds as they are elsewhere. They are not, however, placed at regular intervals,
but become more and more closely placed as they approach the projecting edge or crest of
the fold ; while the first bar of the fold shows but little difference from the arrangement
between the folds, the fourth, fifth, and sixth are so closely placed that the meshes are
"reduced in places to mere chinks, and are in some cases obliterated (PL VIII. fig. 3,
br.f).

A conspicuous feature in this branchial sac is the presence of spicules in the interior
of the vessels (PL VIII. fig. 3, sp.). They lie in the inner part of the wall of the vessel.
and are present in greatest number in the internal longitudinal bars, and especially near
their points of intersection with the larger transverse vessels into which the spicules
sometime- extend. I have never seen them in the smaller transverse vessels.

These spicules are composed of carbonate of lime, and are often of very considerable
size, up to •;> mm. in their greatest extent. There seems to be no prevalent form or plan
of growth for them, though they have a characteristic appearance, as they are generallv
slender and branching, and the outline is formed of gentle curves, there being no sharp
points or angles. The smallest and simplest forms noticed were minute fusiform spieula ;
these, when a little larger, began to have their outlines somewhat wavy, and frequently
one of tin' ends was forked, or a slight branch had made its appearance near the middle.
From this all stages of complication may lie found up to the largest forms which are
often considerably branched.

On examining these spicules closely with a high power, one notices that they are
invariably marked by a series of delicate lines, of which the outer ones run exactly
parallel to the outline of the spicule, following all its curves, while the more internally
placed lines do so to a less degree, and finally the series ends near the centre of the
spicule in a few concentric curves, the whole having the closest possible resemblance to a
system of contour lines on a. map (PL VIII. fig. 6). These markings no doubl
represent stages in the deposition of the carbonate of lime. In some of the spicules, if
uo1 in all of them, there exists a central cavity, which may be prolonged along the
branches to a considerable extent as fine canals, along which air and staining fluid-
were observed to pass in some of the broken spieula.

The wall of the vessels of the branchial sac is composed externally of a layer of thin

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

squamous epithelium. The cells are large, and have centrally placed round nuclei which
stain brightly with carmine. On the internal longitudinal bars the cells become modified
(PL IX. figs. 5 and 6). Towards the front or most internal part of each bar, the cells begin
to become smaller in superficial area, but deeper, and with larger nuclei. This increases
till they come to a series of cubical or short columnar cells, with large distinct nuclei,
forming a band down the front of each bar.<- These columnar cells I expected to find
ciliated, and probably they were so when living ; I have searched for the cilia carefully,
but in vain. The nuclei of all these cells stain brilliantly with carmine, and under a
moderately high power where the outlines of the cells are not distinguishable, an internal
longitudinal bar in profile presents a curious appearance (PI. IX. fig. 5). The whole
surface is scattered over with red dots, which are larger and very much more closely
placed towards the internal free edge, while further out they diminish in size and are
more distant.

The chief peculiarity about this branchial sac is its open network. The meshes
formed by the intersection of the transverse and internal longitudinal bars (PL VIII.
fig. 3, mh.) are perfectly patent, and are not filled up by any other structure, the entire
system of fine longitudinal or interstigmatic vessels so generally present in the branchial
sac being here completely absent ; so that, strictly speaking, no stigmata are present,
or, better still, the stigmata coincide with the meshes.

TJie Endostyle is a very conspicuous organ iu this species. It is of considerable size,
and has the edges of a bright opaque white colour, so that it is seen at once on looking
into the branchial sac. As usual it has the forrn of a deep groove extending along the
ventral edge of the branchial sac, and bounded laterally by raised pads. The bottom of
the groove is of a rich brown hue, but the prominent edges are of a chalky white colour.

When a small piece of the endostyle is cut out and laid on a glass slide, the edges fall
down outwards and leave the bottom of the groove exposed (PL VIII. fig. 4). One
notices then that the central brown part (PL VIII. fig. 5, c.h.a.) consists of several
narrow longitudinal bands aloug the middle, and two darker and broader bands at the
sides (l.b.b.), all outside the latter being either transparent (t.a) or chalky white (w.e.).
The central narrower bands are of various tints of brownish yellow, but none are so
dark as the lateral bands. Outside these lateral bands is a broad translucent space
{La.), and outside that comes the prominent white border (w.e.) which is now seen to
owe its colour to a series of quadrangular white patches placed side by side, and of which
every alternate patch is considerably brighter than the intermediate ones (PL VIII.
fig. 4). In some parts of the endostyle the lateral brown pads are further from the
centre than usual, and they then lie on the translucent area immediately inside the white
edges.

A microscopical examination shows that the white colour of the patches forming the
edges of the groove is due to the presence of a large number of calcareous spicules matted

REPORT ON THE TUNICATA. 99

together ; and that the brown colour of the bottom of the groove is caused by the granular
brown cell elements in that locality. The spicules are composed of carbonate of lime,
and an- very similar to those found in the vessels of the branchial sac, but here they are
larger and considerably more branched. In the prominent while edge of the endostyle
(PI. VIII. fig. 5, w.e.) each of the quadrangular patches is a dense mass of spicules
closely matted together in the centre, and rather more open at the edges where the tips
of the branches are seen projecting. The different patches are united together by the
branches which stretch from one to the other. The rather denser alternate patches
send down branches of spicules into the translucent area (PI. VIII. fig. 5), while the
intermediate patches, which are not so dense, have no connection with that area.

The translucent area, immediately inside the prominent white edge, has a series of
spicules stretching longitudinally along its centre and leaving a clear space along each
side (PI. VIII. fig. 5, t.a.). Some of these spicules are very complicated, extending for a
great distance, and branching and uniting again so as to form a tangled mass. They are
united to the spicules of the outer white edge by the branches which dip in from the
denser patches, but have no connection with the spicules of the central brown area.

When the lateral brown bands encroach upon the translucent area they lie along the
line of spicules, so as to leave a clear space separating them from the central brown area
internally and from the white edge externally. The central brown area is also provided
with spicules (PI. VIII. fig. 5, c.b.a.), but here they are not nearly so prominent on account
of the strong colour of the cells overlying them. The spicules are arranged in two longi-
tudinal series leaving a clearer space in the middle, across which however they send
branches which unite here and there. They extend laterally slightly beyond the brown
area into the clear band on the inner side of the translucent area, and may even overlap
the tips of the spicules of the translucent area, but they were never observed to unite
with them.

Over the white prominent edge and the translucent area the epithelium forming the
surface of the endostyle is clear and transparent. The cell elements, however, are distinctly
visible. In surface view they are square or polygonal cells of moderate size provided
with distinct dark nuclei. When seen in profile they are cubical. The lateral dark
brown bands are formed of columnar epithelium. The cells are very long and narrow,
and closely packed together. They taper towards their lower ends, and some of them
towards their free ends also. The nuclei are only seen in the profile view of the cells and
are variable in position, being usually in the widest part of the cells, sometimes near the
free end but sometimes deep down The surface view of these cells has the appearance
of a very fine mosaic.

The central brown ana constituting the bottom of the groove is composed of extremely
long columnar epithelium apparently not ciliated. The cell elements are here rather
difficult to distinguish. They are very greatly elongated, and are columnar or fusiform in

(ZOOL. CIIALL. EXP. — PAST XYIL— 1882.) II 1-t

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

shape. No nuclei are distinguishable, but the cell contents are throughout brown and
granular. A finely granular matter, in some places traversed by very delicate strings or
fibrillar, lay along the floor of the groove, covering the tops of the cells ; but nothing of
the nature of cilia could be detected in any part.

The Dorsal Lamina is replaced by a series of languets or tentacular processes (PL
VIII. fig. 8, I.), which are disposed in a single line along the dorsal edge of the branchial
sac from the apex of the peritubercular area anteriorly to the oesophageal opening
posteriorly.

The languets are relatively long and are very closely placed (PI. IX. fig. 14, I.). Each
has an elongated triangular form tapering from the base where it is attached to the pointed
free end. They are about 4 mm. long, and are very delicate and transparent, except
along the lateral edges and the tip, where there is a thickened border.

The histological structure of the languets is exactly similar to that of the internal
longitudinal bars of the branchial sac. They are hollow, and the thin walls are covered
in the greater part of their extent by squamous epithelium, which becomes thickened
towards the edges and the tip, where the cells are cubical, thus forming the darker border.
These cubical cells do not bear cilia.

The Tentacles are large, much branched, and of various sizes (PI. VIII. fig. 7, tn. and
tn.'). They spring from the upper margin of the praebranchial zone, and just at their
bases a strong muscular band, forming the most posterior part of the sphincter muscle,
runs round the lower end of the branchial siphon. There are sixteen principal tentacles,
eight larger and eight smaller, placed alternately; but between these there are others here
and there of a very much smaller size and having no definite arrangement. A mode-
rately sized member of the circle of eight larger tentacles (PL VIII. fig. 7, tn.) is about
12 mm. long, and has from twelve to twenty branches. Some of these branches are
simple, while others, generally about the centre of the tentacle, bear simple lateral pro-
cesses. The eight smaller tentacles (PL IX. fig. 12) are one-third to one-half of the size
of the larger ones, and have generally eight to twelve processes.

The main axis of each tentacle is an elongated tapering sac with thin walls, and has
a ridge or dark band running out from the base to the tip along the upper surface
(PL IX. fig. 12), wdiile the lower or branchial surface is soft and membranous. The
pinnae start off from the sides of the main axis rather towards the under than the upper
surface, and each of them has along its upper edge a dark ridge, while the lower surface
is membranous and plain as on the main axis. This membranous lower surface is also,
both on axis and branches, irregularly puffed out, or thrown into a series of projections
and folds, while the upper surface is straighter, and has the appearance of being more
tightly stretched.

The surface of the tentacles is covered with epithelium, thin and tesselated over the
greater part of the surface, thicker and columnar along the dark band on the upper edge

REPORT ON THE TUNICATA. 101

(PL IX. fig. 13a). The cells of the lower surface and sides are diamond-shaped or short
fusiform, and have distinct point-like nuclei (PL IX. fig. 13b and c). Those of the
band along the upper edge are cubical or low columnar, in most places the latter, and
have nuclei placed near the lower end of the cell, and only seen in a profile view (PL IX.
fig. 13e). A surface view of the dark hand shows the ends of these columnar cells as a
series of closely placed minute round areas (PL IX. fig. 13d). Underneath the epithe-
lium in the tentacles are placed here and there large spicules similar to those of the
branchial sac (PL IX. fig. 13a, sp.). In the interior of the tentacles may also be seen in
many places small collections of the large round yellowish-brown blood-corpuscles (PL
IX. fig. 13a, b.c).

The Prcebranchial Zone or the area lying between the branchial siphon and the
branchial sac, and bounded superiorly by the circlet of tentacles and inferiorly by the
peripharyngeal band, is in this species of moderate breadth (PL VIII. fig. 7). It is
about one-third of the length of the larger tentacles, and the smaller tentacles mostlv
extend just across it to the peripharyngeal band. It is perfectly smooth, and is covered
by squamous epithelium in direct continuity with that covering the lower surface of the.
tentacles.

7'//c Peritubercular Ann, or the dorsal offshoot from the prcebranchial zone, in
which the dorsal tubercle is placed, is triangular in shape (PL VIII. fig. 7, and PL IX.
fig. 15), nearly symmetrical, and relatively large, being nearly twice as long as the breadth
of the prcebranchial zone.

The Dorsal Tubercle, better known perhaps as the "olfactory" tubercle, is small, and
is situated down in the posterior angle of the peritubercular area (PL VIII. fig. 7, and
PL IX. fig. I 5, </./.). It is, however, distinctly visible, and has the form of a hemi-
spherical projection, on the surface of which is a deeply cut groove forming a crescent
with both horns curled inwards. The horns are anterior and posterior, and the concavity
is turned towards the left side.

The Peripharyngeal Band, bounding the pnebranchial zone posteriorly, is well
marked, and has the usual form of a pair of closely placed ridges separated by a narrow
groove. At the dorsal edge of the sac, where the two halves of the peripharyngeal band
turn posteriorly to bound the peritubercular area, the right half is rather higher or more
.■interior than the left (PL VIII. fig. 7, J>.j>.). At the apex of the peritubercular area the
two halves unite at the anterior extremity of the dorsal lamina.

The Nerve Ganglion is of small size, and has an elongated fusiform shape (PL IX.
fig. 15, n.g.). It lies immediately posterior to the dorsal tubercle, its anterior extremity
overlapping that organ dorsally.

The Heart is situated on the right side of the body. It lies on the inner fare of the
mantle towards the ventral edge, about midway between the branchial and atrial aper-
tures, and is placed longitudinally, running parallel with the endostyle, from which it is

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

not far distant. It is an elongated, fusiform, thin-walled sac, and is enclosed by a
membranous pericardium composed of a thin layer of connective tissue uniting an open
network of branched spicules similar to those found in the branchial sac, endostyle, &c.
This is lined by a layer of squamous epithelium. The cells are large, polygonal in
outline, and distinctly nucleated (PI. IX. fig. 11).

The wall of the heart itself is composed of regularly arranged fusiform cells, inter-
locking with each other (PI. IX. fig. 9). These cells are about twelve to sixteen times
as long as they are broad, and are perfectly symmetrical, tapering gradually towards each
end. They have large central distinct nuclei, which stain brilliantly in carmine and
logwood. These cells are all distinctly striated transversely (PI. IX. fig. 10). The
striae appear as dark bands, leaving clear spaces between them ; there are usually about
t \vi nty in each cell.

The Alimentary Canal. — The first portion of the alimentary canal, consisting of the
branchial sac or modified pharynx, has already been described ; there remain still to be
noticed the oesophagus, the stomach, the intestine, and the anus.

The oesophageal opening lies at the posterior end of the dorsal lamina near the
posterior extremity of the branchial sac. It is an irregularly triangular aperture (PI.
VIII. fig. 8, ce.a.), surrounded by a membranous lip of considerable breadth, which is
the termination of the dorsal lamina. The oesophagus (ce.) is a short tube running in
a curved course posteriorly and ventrally so as to reach round the posterior end of th
branchial sac. It then opens into the irregular stomach (st.). This organ lies along the
ventral edge of the posterior end of the branchial sac, and has a remarkable appear-
ance (PI. VIII. fig. 8, St.). It is an irregularly elongated pyriform sac, having its
intestinal or anterior end rather the larger ; its walls are curiously folded and saccu-
lated, so that in external view it is multilobed, and the lobes are covered with bunches
of little rounded processes. From its anterior larger end the intestine emerges. It is
long and simple, but rather twisted in its course, performing several slight undulations.
It runs forwards along the ventral edge of the branchial sac for about half its extent, and
then, turning abruptly, it runs back almost parallel to the first part of its course, but lying
to the left of it, and after curving round dorsally it passes to the left of the stomach and
last part of the oesophagus, to terminate close to the atrial aperture (PI. VIII. fig. 8, a.).
Just at the most anterior part of the intestine where it turns round, an irregular process
projects from it into the narrow loop (PI. VIII. fig. 8, i.e.). This is apparently a caecum
— possibly it may be an individual abnormality.

The whole of the intestine is thin walled, and its surface is smooth and of a dull
leaden-grey colour. The wall of the stomach is thicker, and is of a pale yellowish-brown
colour. There is no typhlosole or projecting fold of any sort in the intestine. The anal
termination is slightly widened, and has an undulating free edge (PI. VIII. fig. 8, a.).
The intestine contained fine mud of a dull brown colour.

e

REPORT ON THE TUNICATA. 103

The Genital Organs consist of a scries of about twelve rudely cubical masses, which
adhere to the inner surface of the mantle proper, and arc covered by the lining membrane
of the peribranchial cavity, into which they project (PL VIII. fig. 10). They are situated
rather towards the ventral edge and occur on both sides of the endostyle, the majority,
however, being on the right side.

Each genital mass consists chiefly of a spherical spermarium or testis out of which
leads a delicate somewhat undulating vas deferens. As the genital masses on each side
are arranged in two or three converging series (PL VIII. fig. 10), the testes in each series
are united by a vas deferens, and the several vasa deferentia then join to form a common
duct (PL VIII. fig. 9, v.d.), which opens into the peribranchial space near the atrial
aperture.

Round the vasa deferentia uniting the different genital masses, and round the genital
masses themselves, lie the ova (PL VIII. fig. 11, ov.), and these continue up to the point
of convergence, where there is a short wide membranous tube serving as an oviduct
(PL VIII. fig. 9, o.cl.) and opening alongside the common vas deferens.

The masses of ova are yellow, while the Lunches of spermatic vesicles composing the
testes (PL IX. fig. 17a and b, t.v.) are pale whitish yellow. The vasa deferentia show
as opacpie white lines running through the masses of ova. The ova are in various
stages of development, very young ones, in which there is httle vitellus round the
germinal vesicle (PL IX. fig. 16b), being numerous. The more mature ova (PL IX.
fig. IGa) are enclosed each in a capsule formed of cubical or low columnar cells (PL
IX. fig. 16c).

Two specimens of this species, one of them somewhat injured, were obtained in the
Pacific Ocean, west of Japan.

Station 241. June 23, 1875. Lat. 35° 41' N., long. 157° 42' E.; depth, 2300
fathoms; bottom temperature, 1°"1 C; red clay.

< hdeolus wymlle-thomsoni, Herdman (PL X. figs. 1-6, and PL XIII. figs. 5 and 6).

C Ki/ril/r-fhnmsoni, Herdman, Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 84.

External Appearance. — In this species the "body "part is rather larger and the
peduncle shorter than in Culeolus murrayi. The general shape of the body (PL X.
fig. 1) is irregularly pyriform, or almost wedge-shaped, on account of the great difference
in the width at the two ends ; there is no Literal compression. The anterior end, where
the stalk is attached, is narrow and tapering. The posterior end, on the contrary, is very
broad, but not so much rounded as in the last species. It is divided by the atrial aperture
into a dorsal and a ventral portion. The latter is straight, has a truncated appearance,
and forms almost a right angle with the posterior extremity of the ventral edge. The
dorsal portion, on the contrary, is rounded off, forming a gentle curve, ami becoming con-
tinuous with the dorsal edge. The dorsal and ventral edges are very irregular, more so

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

than in Culeolus murrayi, and diverge as they recede from the anterior end. The
greatest width is reached at about two-thirds of the length of the body from the anterior
md. From this point the ventral edge runs with a slight ventral inclination to meet
the posterior end, while the dorsal edge curves round as described above. The sides are
irregularly but about equally convex.

The peduncle is not long ; it is thin, wiry, stiffer than in the last species, but not so
flexible, and is bent in a gentle curve towards the dorsal side of the body. It is attached
to the anterior end of the body, and turns dorsally at a right angle, so as to cross the
branchial aperture (PL X. fig. 1). From its point of attachment it runs for a short
distance partly imbedded in the test, and disappears on the ventral edge. It becomes
thickened at the upper extremity where it is continuous with the anterior end of the
body, and is somewhat spread out at its lower end so as to form a base of attachment ;
otherwise it is of much the same thickness throuohout.

The branchial aperture is placed close to the anterior extremity, at the commence-
ment of the dorsal edge and immediately below the peduncle (PI. X. figs. 1 and 2). It
is sessile but very conspicuous, and, as in the last species, is large, open, and triangular
in shape — the base being anterior and the apex posterior. It has a smooth lip, bordered
by a ridge, which, on the posterior side, is cut up into a series of blunt papillae placed
side by side. The branchial aperture looks almost directly anteriorly. The atrial
aperture is at the opposite end, being placed in the centre of the large posterior ex-
tremity, and looks directly posteriorly. It is sessile, conspicuous, large, and open. It is
bilabiate, and presents the form of a transverse slit, having smooth lips, and a conspicuous
raised border on the ventral side (PI. X. figs. 1 and 3).

The surface is very irregular. It is raised into prominent, rounded, pad-like, longi-
tudinally running ridges, separated by deep creases. These ridges are again subdivided
by slighter transverse creases into small irregularly-shaped elevated areas, each of which
bears in its centre a small but prominent papilla, which may be sharp-pointed. Other-
wise the surface of the body is perfectly smooth. The peduncle is finely grooved
longitudinally throughout its length.

The colour of the body is a pale grey, having a bluish hyaline appearance in some
parts, and a warmer yellowish tinge in others. The peduncle is rather bluer, being of a
pale slate-grey throughout.

The dimensions are as follows : —

Length of the body (antero-posterior),
Breadth of the body (dorso-ventral),
Thickness of the body (lateral),
Length of the peduncle,
Thickness of the peduncle (average),

The Test is rather thick. It has a cartilaginous aj>pearance, but is quite soft ; it is,

5

cm.

4

?>

3-5

»>

10-5

jj

1-5

mm

TtEPORT ON THE TUNICATA. 105

however, stiff, and not flexible like that of Culeolus rnurmyi. The thickness varies
considerably, being much greater on the longitudinal ridges than in the hollows between.
Its external surface is perfectly smooth, except where it is raised up to form the pointed
papillae above described.

The test is quite opaque on account of its thickness ; here and there, in the thinner
parts, it has a hyaline translucent appearance. Over the whole surface minute, opaque,
light brown dots are thickly scattered, and are especially numerous at the anterior
end and round the base of the peduncle. A microscopical examination of thin section-
shows that these dots arc comparatively large chambers in the test in connection with
the blood-vessels which will be described shortly. The inner surface of the test is smoot b
and glistening — as usual I lie mantle adheres to it.

In its minute structure this test corresponds closely to that of Culeolus murrayi.
The chief difference lies in the disposition of the blood-vessels. In the present species
they are greatly developed, the test being much more vascular than in the last species.
In all the sections vessels were numerous, though most of them were of small size.
They branch and anastomose, ramifying through all parts of the test, and ending
frequently near the external surface in small rounded knobs. The finer vessels are
peculiar on account of the great distances to which they extend, and their frequently
zig-zag and cork-screw-like course (PI. X. fig. 4). Here and there, in the deeper parts of
the test, one comes across sections of the large trunks from which the smaller vessels
arise, but these are rare. Large cavities or reservoirs are also met with, both in the
deeper parts of the test, and, as in the last species, just under the external surface ; but
they are very rare. These cavities are usually filled with masses of reddish-brown blood-
corpuscles (PL X. fig. 4, b.c), and thus appear externally as the light brown dots
mentioned above.

In the creases on the outside of the test there may be seen numbers of small delicate
finger-like processes projecting beyond the surface, and in many cases these may be
traced down for a short distance through the test (PL X. fig. 4, t. p.), and observed
opening into one of the many fine vessels ramifying in the superficial layer. The finger-
like processes are hollow, and extremely thin-walled ; blood-corpuscles may be noticed
here and there in their interior, and there can be no doubt that they correspond to the
papillae covering the external surface of the test in Culeolus murrayi. In the present
case, besides being much fewer in number, they are far smaller, and their bases are not
expanded to form large cavities as in the other species. In the other details of its minute
structure, this test exactly resembles that of Culeolus murrayi.

The Mantle in this species is rather thin in relation to the size of the body. As in

the last species, it adheres slightly to the inner surface of the test, but is easily detached.

The muscle Lands are strong but distant. Most of them run transversely. A few,

however, are longitudinal, and cross the first at right angles, so as to form a wide

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

rectangular network. Sphincters can scarcely be said to be present. In minute structure
the mantle is precisely similar to that of the last species.

The Branchial Sac. — As the branchial sac is formed on the same plan as in Culeolm
murrayi no detailed description is necessary. There are six longitudinal folds on each
side, and they diminish in size from the dorsal to the ventral edge, those next the endo-
style being very slight.

The transverse vessels are of three distinct sizes, and are arranged in the following
manner (PL X. fig. 5) : — Intermediate between every two of the largest (tr.) is a
middle-sized one (tr,') separated from each of the largest by three of the smallest size
{tr.") (see also fig. 14, p. 122) so that we have in series a large one, three small ones,
a middle-sized one, three small ones, and a large one ; consecpiently seven smaller trans-
verse vessels are interposed between each pair of large ones.

Both transverse vessels and internal longitudinal bars are much closer than in Cule-
olus murrayi, and consecpiently the meshes are much smaller, usually one-eighth of the
size ; they are transversely elongated (PL X. fig. 5, and PL XIII. fig. 5), and their length
is usually to their breadth about in the proportion of five to three.

The calcareous spicules in the vessels are much smaller and less branched than in
Culeolus murrayi, but they are more numerous. They are especially plentiful in the
internal longitudinal bars. The most common form is a simple elongated spindle,
frequently bifurcated at one of the ends or having a branch from the middle so as to
form a triradiate spicule.

The Endostyle is conspicuous, and has prominent lips as in the last species, but they
are not white. Branched calcareous spicules are present in large numbers, but they do
not form such dense masses along the sides, thus accounting for the want of whiteness in
the lips. Along the edges, in the region occupied in Culeolus murrayi by the quadrate
masses of spicules, are arranged a series of very large, branched, usually irregularly
pinnate or fan-shaped spicules (PL XIII. fig. 6, s-p.). Between these there are generally
smaller and slighter spicules. From this point inwards to the centre of the endostyle,
the spicules are numerous and of moderate size, generally having the branches longer
and more slender than those in Culeolus murrayi. The central third of the organ is
traversed by dark yellowish-brown longitudinal bands as in the last species ; they
represent prominent ridges of columnar epithelium. The very centre of the groove
has a clear line down it, bounded on each side by a broad brown band (PL XIII.
fig. 6, c.b.a.), outside of which, separated by slight intervals, are two narrow brown
bands (l.b.b.).

The Dorsal Lamina is represented by a series of languets (PL X. fig. 6. d.l.). They
are large, of an elongated triangular form, and are very closely placed.

The Tentacles are sixteen in number and are branched. They are of two sizes (PL X.
fig. 6), and are placed large and small alternately. The tentacles in the two sets vary,

REPORT ON THE TUNK'ATA. 1(17

however, in size, and the large one situated close to the dorsal tubercle (tn.) is gigantic
compared with the others. The ordinary large ones (tn/) are about twice the breadth of
the prsebranchial zone, while the small ones are only one-fourth or one-third of that size.
Calcareous spicules are present, bu1 they are noi so numerous as in Culeolus
murrayi.

The Dorsal Tubercle is small, but distinct. It has a cordate form, with both horns
turned inwards, and the opening directed towards the right side (PI. X. fig. 6).

The Peritubercular Area is not so deep as in Culeolus murrayi, and has not such a
regularly triangular form. Its depth is about equal to the breadth of the prsebranchial
zone on the right (or broader) side (PI. X. fig. 6).

The Peripharyngeal Band at the edge of the peritubercular area extends further up
on the left side than on the right, so as to narrow the prsebranchial zone on that side.

There is only a single specimen of this handsome species in the collection. It is
in most excellent condition, and was dredged in the South Pacific Ocean, to the north of
the Kermadec Islands.

Station 170. July 14, 1874. Lat. 29° 45' S., long. 178° 11' W. ; depth, 630
fathoms ; bottom temperature, 4° C. ; hard ground, volcanic mud, and pieces of
pumice, &c.

Culeolus recumbens, Herdman (PI. XI. figs. 1-7, and PI. XII. figs. 1-7).

Oideolus recumbens, Herdman, Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 85.

/■'.rfenial Ajipeara nee. — In this species the body is much smaller than in either of the
preceding forms. Seen laterally (PI. XL tigs. 1 and 2) its shape is irregularly quadrate
with the angles rounded. It is elongated antero-posteriorly and rudely sub-cylindrical,
being slightly compressed laterally. Both ends are blunt; the anterior is rather nar-
rower than the posterior ; and the posterior is the more convex of the two. The dorsal
and ventral edges are nearly parallel, tapering slightly anteriorly ; the dorsal is nearlv
straight, while the ventral is a little convex, especially towards the posterior end.

The peduncle is long, thin, and tough; it is not stiff, as in the last two species, but
is very flexible, and in general appearance resembles a piece of thin string. It is attached
at the anterior end of the body on the ventral side of the branchial aperture, and in the
iii.-i part of its course it runs directly ventrally, so as to leave the branchial aperture
exposed, instead of crossing it as in Culeolus murrayi and Culeolus wyville-thomsoni.
This directly ventral course is, however, of very short extent (1-2 mm.), as it soon turns
abruptly to the right and describes a nearly semicircular curve, and then leaves the
surface of the test to which up to this point it has been closely adherent (PL XI.
tigs. 1 and 3). It is of uniform thickness throughout, except at the lower end, where
for the last few millimetres it becomes slightly thickened, and then break- up into a

(ZOOL.CHALL.E.\r. — r.VRT xvu. — 1882.) 1. la

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

mass of tangled filaments which have evidently been rooted in globigerina ooze (PI. XI.
figs. 1 and 2).

The branchial aperture is at the anterior end, terminal, and almost or quite median,
being sometimes slightly dorsal. The insertion of the peduncle just at its ventral edge
causes that point to be the most prominent part of the anterior end, and so to throw the
branchial aperture a little dorsally. The aperture is sessile, conspicuous, and of consider-
able size. It has the form of a triangular slit (PI. XL fig. 3), elongated transversely,
and having the apex directed dorsally. It has a raised lip all round, cut up into a series
of blunt rounded papillae placed closely side by side. The branchial aperture is directed
either anteriorly or anteriorly and slightly dorsally.

The atrial aperture is not so far distant as in the two previously described species. It
is situated at the junction of the dorsal edge with the dorsal extremity of the large curved
posterior end, and looks dorsally and a little posteriorly. It is sessile but prominent,
conspicuous, of moderate size, and slightly open. It has the form of a transversely elon-
gated elliptical slit (PI. XL figs. 1, 2 and 4), with a raised lip on both edges, formed, like
that round the branchial aperture, of a series of close-set blunt papilla). This aperture is
about two-thirds of the way from the branchial aperture to the middle of the posterior end.

The surface of the body is regular and even, and is pretty smooth. Here and there
sprinkled over it there are slight papillae and granulated patches. Pound the posterior
end, however, and enclosing the atrial aperture, there is a band of closely placed, slightly
larger papillae or processes, forming a structure like that seen in a similar position in
Culeolus murrayi. It is quite a narrow band, but is continuous, and forms a ring cutting
off obliquely about the posterior fourth of the body from the rest. Dorsally it skirts the
anterior margin of the atrial aperture (PI. XL figs. 1, 2 and 4), while its ventral part
separates the posterior end from the ventral edge of the body, or may lie even more
posteriorly, so that its direction, viewed laterally, is from the dorsal edge ventrally and
posteriorly.

The colour of the body is a pale grey, in some places having a yellowish-white
appearance. The peduncle is yellowish-white or of a dirty cream colour.

The dimensions are as follows : —

Length of the body (antero-posterior), . . . . . . 2-5 cm.

Breadth of the body (dorso-ventral), . . . . . . .17,,

Thickness of the body (lateral), . . . . . . . . 1 -5 „

Length of the peduncle, . . . . . . . . . 14 „

Thickness of the peduncle, ........ 1 mm.

TJie Test is thin and flexible, but tough. It is almost opaque, being only semi-
transparent in parts. The outer surface is rough and irregular, and is considerably
coated with Foraminifera, sand-grains, mud, &c.

In minute structure it is very compact (PI. XII. fig. 1). The matrix is close and

REPORT ON THE TUNICATA. 109

homogeneous, and contains only small rounded protoplasts. In several sections examine I
no vessels were found ; so that, if they are present in this test, they must be few in number.

Sections through the peduncle (PI. XII. tig. 2) show it to have a structure very similar
to that of Cideolus murrayi. The matrix is like that of the test covering the body, and
contains similar minute rounded protoplasts. It is perforated by several large holes
(PI. XII. peel, c), the sections of large tubes running longitudinally along the peduncle,
and each of them containing a large blood-vessel in its interior.

The outer surface of the peduncle has adhering to it a considerable quantity of sand-
grains, Foraminifera, shell fragments, &c, and in the sections one finds similar particles
imbedded iu the matrix often far distant from the surface (PI. XII. figs. 1 and 2).
These have doubtless become surrounded by the outward growth of the peduncle.

Tin- Mantle is very thin, and has the form of a delicate membrane adhering closely to
the inner surface of the test, from which it is separated with difficulty. The musculature
is feeble, consisting of a scries of distant transverse bands crossed by slighter and more
irregular longitudinal bands.

The Branchial Sac is a coarse network — the vessels being strong for the size of the
body. There are several longitudinal folds on each side of the sac, but they are very
slight. The internal longitudinal bars are wide and prominent. They are regularly
placed, and are apparently the strongest part of the network. The transverse vessels
are all of the same size, but they are irregular, and are much slighter than the internal
longitudinal bars. Usually the meshes are rather large and are elongated longitudinal I v
(PI. XI. fig. 5, and PI. XII. fig. 3) — the breadth being about three-fourths of the
length, but occasionally irregularly placed intermediate transverse vessels (PL XL fig. 5,tr'.)
are present, and sometimes oblique or longitudinal vessels (I. v.), usually of small calibre,
are given off from the transverse vessels, thus breaking the mesh up into compartments,
and suggesting the formation of true stigmata.

The calcareous spicules are not at all prominent, on account of their small size, but
they are pretty numerous, and often ramify considerably (PL XL fig. o, and PL XII. fig.
.".. sp.). They are mostly more branched and more irregular than those of cither Cuholus
murrayi or Calculus wyville-thomsoni. As usual they are present chiefly in the internal
longitudinal bars.

The Endostyle is broad and distinct. The prominent edges have a creamy white tint,
while the groove is brown (PL XII. tig. 4).

Calcareous spicules are not present in such numbers as in either of the preceding
species. The raised edges (w. e.) in which they are situated are semi-transparent, ami each
equals in breadth about one-fifth of the breadth of the entire organ. The spicules are
large and considerably branched but are not numerous. They resemble those of the
central part of the endostyle of Culeohis murrayi.

Laside each edge is an opaque brown area of about the same breadth as the edge (l.b.b.),

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

and divided into an outer broad lighter, and an inner narrow darker band formed of
closely packed columnar cells (PI. XII. fig. 5). Between the two opaque brown areas
lies the central fifth, which is semi-transparent but darker than the raised edge. Neither
the opaque brown areas nor the central clearer part contain spicules.

The Dorsal Lamina is replaced by a series of large triangular languets. They are
not broad at the base, and taper gradually to a blunt point. They are moderately
closely placed, there being about two to each mesh — one opposite each transverse vessel
and one between each pair.

Tlie Tentacles are branched and are very long. There are about twenty-four of them,
and they are of two sizes, placed alternately. They are more branched and larger in
comparison to the size of the body than in either of the preceding species. One of
the ordinary large tentacles measures about 9 mm. in length. Ramifying calcareous
spicules are present here and there, but they are not at all numerous.

TJie Dorsal Tubercle is of small size and is ellipsoidal in form, having no aperture,
and consequently no horns (PI. XL fig. 6, d.t.). It lies near the posterior angle of the
large triangular peritubercular area, and is immediately below the nerve ganglion, being-
situated at the right side of its anterior end.

The peritubercular area is large and of an irregularly triangular form. It is not,
however, very deep, being broad at the anterior end. The peripharyngeal bands are
narrow and undulated. As in the last species the band extends further forwards on
the left side of the peritubercular area than on the right (PL XL fig. 6, p.p.).

The Nerve Ganglion is of considerable size, and much elongated antero-posteriorly.
It is narrow and of much the same calibre throughout, swelling slightly in its atrial half.
It lies with its middle point placed about the apex of the peritubercular area (PI. XL
fig. 6). The branchial end divides into two divergent nerves (br.n.), at the origin of one
of which (the right) the dorsal tubercle is situated. The atrial end of the ganglion gives
off four nerve trunks, two ]30steriorly side by side (at.n.) and two laterally at right angles
to the axis of the sano-lion, one to each side. The left one soon subdivides into two
branches.

The Alimentary Canal. — The oesophageal opening (PL XL fig. 7, a?.) is at the posterior
end of the branchial sac, and the oesophagus is a short round tube running ventrally and
anteriorly to enter the large stomach (st.) which lies along the left side of the ventral edge
of the branchial sac. Like the stomach in Culeolus murrayi it is very irregular. It has
three prominent lobes or pouches, each of which ends in a large number of small papilla-like
processes. The intestine emerges from the anterior narrower end of the stomach, and
continues its direction forwards on the left side of the branchial sac, and then curves
round in a wide loop dorsally, and runs posteriorly as far as the level of the intestinal
end of the stomach, and there ends in the anus («.) which has its margin cut into a
papillary fringe.

REPORT ON THE TUNICATA. Ill

Genitalia.— There arc three genital glands on each side adhering to the inner
surface of the mantle They arc of an elongated pyriform shape, and have moderately
long ducts attached to them (PI. XI. fig. 7, </.).

The three on the left .side lie in the intestinal loop and close to the ventral side of the
rectum or terminal part, They arc placed with their long axes dorso-ventrally and are
in a row, one being anterior, one posterior, and one in the middle. The posterior one is
in a line with the anus towards which the ducts of all three converge. The duct of the
anterior gland is about three times as long as that of the posterior one, while the middle
one has a duct of intermediate length.

The three glands on the right side are more closely placed than those on the left.
They lie on the inner surface of the mantle about half-way between the atrial aperture and
the stomach, with their ducts directed towards the atrial aperture and their sides touching.
The ducts of all three are of much the same length.

Each gland is a pyriform mass containing ova and spermaria, and the duct is double,
consisting of a shorter and wider oviduct, and a longer and narrower vas deferens which
runs alongside the oviduct but projects beyond it.

There are eight specimens of this species. They were all taken in the Southern
Ocean, about half-way between the Cape of Good Hope and Kerguelen Island.

Station 14G. December 29, 1873. Lat. 46° 46' S., long. 45° 31' R; depth, 1375
fathoms ; bottom temperature l0-5 C; globigerina ooze.

Culeolus perlucidus, Herdman (PL XL figs. 10-14, and PI. XII. figs. 8-12).

Ouleolus ji'ii '/(<•/( /«.-,-, Herdman, Preliminary Report, Proc. Roy. Soe. Edin., 1880-81, p. 86.

External Appearance. — In this species the body and stalk have much the same
proportions as in Culeolus recumbens. The shape of the body is somewhat ovate or
pyriform, gracefully curved, and scarcely compressed laterally (PI. XL fig. 10). The
anterior end, where the body becomes continuous with the stalk, is produced and
tapering, while the posterior end is rounded and broader, though it is by no means the
widest part of the body. The dorsal edge is slightly convex forming a gentle curve,
but the ventral is extremely convex, especially at the anterior end, where it rises from
the narrow extremity in a bold curve, which attains its greatest height at about one-
third of the way to the posterior end. The two sides are equally convex.

The peduncle is long and thin, flexible, but stiffer than that of Culeolus recumbens.
It is perfectly transparent and looks like a delicate glass spine. It is attached to the
anterior end of the body, at some distance from the branchial aperture, ami is bent at
a right angle at tin; point of attachment, so that it runs ventrally and describes a gentle
curve towards the posterior end. From the anterior end it is continued, attached to the
test, along the dorsal edge fully half-way to the branchial aperture (PL XI. fig. 10).

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

This upper extremity and the base are slightly enlarged, otherwise the peduncle is of
the same thickness throughout.

The branchial aperture is situated on the dorsal edge near the anterior end, and about
one-fourth of the distance from the point of attachment of the peduncle to the posterior
end. It is very conspicuous, and projects slightly from the surface of the test. It has
the form of a transverse slit, large and open, and having its posterior edge arched so as
to form an approach to the triangular outline seen in the preceding species. The lips are
large and prominent, especially the posterior one, but smooth ; no papillary fringe is present.
The branchial aperture is directed anteriorly and slightly dorsally (PI. XL fig. 10).

The atrial aperture is not very distant from the branchial, being situated at the
junction of the dorsal edge with the rounded posterior end, and is directed dorsally and
posteriorly. It is conspicuous, but not so prominent as the branchial aperture, is of
moderate size, and gapes slightly. It has the form of a transverse slit bounded by raised
anterior and posterior lips which are both smooth.

The surface is regular, but finely granular from the presence of minute processes all
over, except on the lips of the apertures which are perfectly smooth. The surface of the
peduncle and its continuation along the dorsal edge are also smooth.

The colour is a light grey, with a translucent appearance. The peduncle is hyaline
and transparent.

The dimensions are as follows : —

Length of the body (antero-posterior),

2 cm.

Ureai 1th of the body (dorso-ventral),

1.4 „

Thickness of the body (lateral),

1-3 „

Length of the peduncle,

about 11 „

Thickness of the peduncle,

7 mm

TJie Test, like that of Culeolus recumbens, is thin and flexible, but tough. Unlike it,
however, it is transparent. It is very compact, and in minute structure resembles that
of the last species. The matrix is very close and homogeneous, and contains only rounded
and elongated protoplasts, generally arranged parallel to the surface. In the sections
examined no vessels were present, but every here and there along the inner surface small
pouches or excavations in the matrix were discovered containing blood-corpuscles (PI.
XII. fig. 8, v.). These are doubtless diverticula from the sinuses of the mantle.

The outer surface is rough from the presence of minute processes rising occasionally
into small papillas which may equal the thickness of the test in height (PL XII. fig.
8, t.p). These have generally sand-grains and minute particles of mud adhering to
them, but the general surface is not coated as in the preceding species.

The peduncle is hollow. It is a thin-walled tube, the thickness of the wall being
only about one-sixth of the total diameter. The interior of the tube is lined by a
membrane formed of tesselated epithelial cells, diamond-shaped or short fusiform, and

REPORT ON THE TUNICATA. 113

distinctly nucleated, closely resembling the epithelial lining of the blood-vessels in the
peduncle of Culeolus murrayi. No blood-corpuscles were noticed in the interior of this
tube, but there can be little doubt that it is a great sinus in connection with the blood-
vessels of the mantle.

The wall of the tube has the same structure as the test over the body, and has no
vessels in it. The outer surface is very smooth, and has no foreign matter adhering or
imbedded as in the last species.

The Mantle is a very delicate membrane which does not adhere closely to the test
as in Culeolus recumbens, but is easily separated. The musculature is feeble, and
consists, as in the last species, of intersecting bands of fibres. The network formed,
however, is very irregular, as the bands are not arranged in parallel series.

Tlie Branchial Sac is more delicate than that of Culeolus recumbens. As in that
species there are several longitudinal folds on each side of the sac, but they are very
slight, being of the simplest form possible — merely a second internal longitudinal bar
attached to each of the normal ones by a short connecting piece at each transverse
vessel (PI. XL fig. 11, ir.f.). These secondary internal longitudinal bars, representing
the ful i Is, project into the interior of the cavity. The transverse vessels are moderately
wide, all of one size, and placed distantly. Occasionally, however, much slighter inter-
mediate transverse vessels are present (PI. XL fig. 11, tr.'), dividing the meshes.

The meshes formed by the intersection of the large transverse vessels and the internal
longitudinal bars are nearly square, the antero-posterior extent being generally slightly
the greater. Each mesh is divided into two by a delicate longitudinal vessel running from
each transverse vessel to the next, and placed about midway between the two internal
longitudinal bars (PL XI. fig. 11, l.v.), so that, going round the sac dorso-ventrally, one
comes upon two internal longitudinal bars united to form a fold, a narrow longitudinal
vessel uniting the transverse vessels, and then other two internal longitudinal bars, and
so on. These narrow longitudinal vessels springing from the transverse vessels are of
course homologous with the fine interstigmatic vessels of most branchial sacs, so that in
the present species the mesh might be correctly described as containing two stigmata.

In the portions of the branchial sac examined, no calcareous spicula were detected ;
but as in some of the other species the spicules were absent over considerable areas, and
as they are sometimes very small and difficult to distinguish, I prefer to think that
spicules, though doubtless few and minute, are probably present in this species, than to
suppose that it differs from all the other species of the genus, which it otherwise so closely
resembles, in this important particular.

T/ie Endosti/le. — This organ is narrow, and not nearly so conspicuous as in Culeolus
recumbens. The most striking peculiarity, however, is that no calcareous spicules can be
detected in any part of it.

As in all the preceding species of Culeolus, there is a clear edge on each side, and a

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

central area traversed by longitudinal opaque brown bands (PI. XII. fig. 9). The
clear edge (iv.c), usually so abundantly provided with spicules and forming such a
favourable locality for observing them on account of its transparency, exhibits no trace of
them whatever. It is on each side fully a quarter of the total breadth of the organ, and
is covered with squamous epithelium. The edge is bounded internally by an opaque
brown band (l.b.b.) of moderate breadth. This, the lateral band, is separated from the
central brown area by a clear space of moderate breadth. The central area (c.b.a.) has a
median broad dark brown band running down the centre and in places traversed by a
central fine clear line. This broad band is separated by a narrow clear space from a
narrow very dark brown band on each side. These narrow bands bounding the central
area, are a little irregular in their course.

The Dorsal Lamina is represented as usual by a series of languets. They are
triangular in form, rather wide at the base and tapering to a point. They are rather
closely placed.

The Tentacles are numerous. A few of them are much larger than the others, being
of considerable size, and are much branched (PL XII. fig. 10, tn.). The remainder
are all much smaller, but are of various sizes (tn/ tn"), and have apparently no definite
arrangement.

The Dorsal Tubercle lies near the posterior end of the large and very irregular peri-
tubercular area (PI. XL fig. 12). It has the form of a short sugar doaf, the base or
open (?) end being posterior and turned towards the right side, while the pointed end is
directed anteriorly and to the left, and seems to be in direct connection with the anterior
extremity of the nervous mass. The peritubercular area is large and wide ; its breadth
at the mouth is fully greater than its depth.

The Peripharyngeal Bands are narrow but distinct. Where they bound the sides of
the peritubercular area they have a very irregular course (PL XL fig. 12, p.p.), undulating
and forming sharp folds, so as to give the generally triangular peritubercular area a very
complicated outline.

TJie Nerve Ganglion lies at the apex of the peritubercular area (PL XL fig. 12, n.g.).
It is much shorter than in Culeolus recumbens and has an oblong form, narrowed slightly
towards the ends. The posterior extremity splits into two large nerve trunks, while the
anterior is hidden in the pointed extremity of the dorsal tubercle.

The Alimentary Canal lies on the left side of the branchial sac. The oesophagus is
very short and passes over imperceptibly into the large stomach (PL XL fig. 13, st.),
which is a long irregularly fusiform body with no cajcal processes as in Culeolus
murrayi and Culeolus recumbens. The intestine, after emerging from the stomach,
continues its direction for a short distance, and then turns in a wide loop and
runs back parallel to the stomach, with the edge of which it is in connection,
passes close to the oesophageal aperture, and, curving up dorsally, ends close to the

REPORT ON THE TUNICATA. 115

atrial aperture (PI. XI. fig. 13, (/.). The long axis of the stomach and of the greater
part of the intestine lies antero-posteriorly.

Genitalia. — There is a single large genital gland on the inner surface of the mantle
on each side. Both are of pyriform shape and have short ducts directed towards the
atrial aperture (PL XI. fig. 13).

The gland on the left side is the larger of the two. It lies alongside the intestine,
not in the loop, and has its long axis parallel to that of the stomach. The gland on the
right side is considerably shorter than the other. The aperture of its duel is not far
from the anus (PL XI. tig. 13).

Each of the glands contains both masses of ova and spermaria arranged so as to form
the wall of a large cavity which occupies the interior of the pyriform mass (PL XII.
fig. 11). From sections of the gland one learns that the spermaria are arranged along
the outer surface and form a compact layer (PL XII. fig. 11, t.v.), while the ova (o.)
occupy the inner part next the centra] cavity, into which they project irregularly.

The ducts from the glands are short and consist of a closely applied oviduct and vas
deferens, the former being the wider, and the latter slightly the longer of the two.

There are three specimens of this species, two of which were more or less injured.
They were obtained in the Southern Ocean between the Cape of Good Hope and
Kerguelen Island.

Station 147. December 30, 1873; Lit. 46° 16' S., long. 48° 27' E. ; depth, 1600
fathoms ; bottom temperature, 0°.8 C. ; globigerina ooze.

Cvleolus perlatus, Suhm (sp.) (PL XL figs. 8 and 9, and PL XIII. figs. 1 and 2).

Boltenia perlata, Suhm, MS., 1873.

Culeolus suhmi, Herdman, Preliminary Report, Proc. Roy. Soc. Edin., 1880-81, p. 86.

External Appearance. — This is the smallest of the six species, and it has much the
shortest stalk. The general form of the body is between ovate and wTedge-shaped, the
anterior end being very narrow, and the posterior much wider (PL XL fig. 8). Tin
form is most definite and the outline regular; there is no lateral compression. The
anterior end is narrow but not so produced as in the last species. The posterior end is
broad but not rounded. It is an oblique line sloping backwards to form an angle with
the end of the ventral edge, and dorsally becoming continuous by a gentle curve with
the dorsal edge. The two edges are very different. The dorsal is strongly convex, rising
suddenly behind the branchial aperture, and attaining its greatest height at about one-
third of the distance to the posterior end ; the ventral edge, on the other hand, is
almost straight, forming a long low arch from the end of the peduncle anteriorly to the
line of junction with the posterior end. The two sides arc equally curved.

The peduncle is not long and is rather thin, but stiff (PL XL fig. 8). It is attached
to the anterior end of the body, and continues the line of the ventral edge. It turns
dorsally at a right angle and its course is straight as a whole, although it makes one or

(zool. cuall. Exr. — i'akt xvu. — 1882.) I; 1(3

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

two slight undulations. From its point of attachment it is traceable for a short distance
along the ventral edge, imbedded in the test. The upper and the lower ends are both
thickened, elsewhere it is of uniform thickness.

The branchial aperture is large, prominent, and very conspicuous. It is situated at
the anterior end and is terminal and median, being directly under the curve of the
peduncle (PI. XI. fig. 8). It has the form of a long transverse slit, gaping consider-
ably, and bounded by prominent, smooth, dorsal and ventral lips. It looks directly
anteriorly.

The atrial aperture is situated at the posterior extremity of the dorsal edge, just
where it passes over into the posterior end. It is sessile, but large and conspicuous, and
has the form of a transverse elliptical slit gaping slightly and bordered by smooth anterior
and posterior lips. It is directed dorsally and slightly posteriorly.

The surface is regular, but rough all over from the presence of minute pointed papilke.
Surrounding the atrial aperture, and cutting off about a third of the body, is a band of
slightly larger papillae forming a ridge like those already described in Culeolus murrayi
and Culeolus recumbens. In this species the band is not broad but is compact and
continuous, and of the same breadth throughout its course (PL XL fig. 8). It runs
from the sharp angle formed by the junction of the ventral edge and the posterior end
across the side of the test in a slightly undulating course to cut the dorsal edge at the
highest point in its curve, about one-third of the distance from the anterior to the
posterior end. It runs therefore from the most posterior point of the body anteriorly and
dorsally. The surface of the peduncle is slightly roughened, but it has no sharp papillae.

The general colour of both body and peduncle is an earthy brown. Closer
examination shows that the ground colour of the test is really much lighter, being a pale
greyish brown, and that the darker effect is due to the presence of the numerous fine
papilla? which are of a very dark brown.

The dimensions are as follows : —

Length of the body (antero-posterior), .... 8 mm.

Breadth of the body (dorso-ventral), .... 5-5 ,,

Thickness of the body (lateral), . . . . . 5 ,,

Length of the peduncle, ...... 5 cm.

Thickness of the peduncle, ...... -5 mm.

The Test is thin, but tough and rather stiff. It is quite opaque. Its outer
surface is very rough from the presence of a great number of minute, closely
placed, dome-shaped, or pointed papillae, which are scattered all over it. Each of
these papillae stands in a little area of the test separated off by a slight ridge, and the
papillae are so closely placed that these ridges divide the entire surface of the test into
diamond-shaped, hexagonal, or polygonal areas (PL XIII. fig. 2). These ridges, as well
as the papillae, are of a blackish brown colour, while the tint of the remainder of the test
is much liohter. There is no foreign matter adherinp; to the surface of the test.

The surface of the peduncle is slightly uneven, and examination under a low power of

REPORT ON THE TUNICATA. 117

the microscope reveals that this is due to the presence in the interior of a number of
trabecules, which form a close network and cause projections on the surface from the
sinking in of the matrix over the meshes (PI. XIII. fig. 1). The trabecule (t.m.c.)
arc of a rich brown colour, and stand out from the surrounding material (t.m.), which
is much paler and less opaque. Probably these trabecuke are of the same nature as the
cornified liars of test matrix separating the blood channels in the peduncle of Culeolus
murrayi.

The Mantle is a very delicate membrane, and the musculature is feebly developed.

The Branchial Sac is very delicate and has several slight folds on each side. These
are formed in the usual manner, and each has about four internal longitudinal bars (PI. XL
fig. 9, br.f.). The transverse vessels are narrow and are all of one size. The internal
longitudinal liars are wider, forming the strongest part of the network.

The meshes are large and are nearly square, usually a little elongated transversely
(PI. XL fig. 9) ; in the row on each side of the dorsal lamina they are more elongated,
the transverse extent being to the longitudinal in the proportion of six or seven to four ;
no secondary transverse vessels, fine longitudinal vessels, or other irregularities were
observed.

Calcareous spicules are present in the internal longitudinal bars. They are not very
numerous but are large and branched slightly, resembling those of the branchial sac of
Culeolus murrayi.

Ti,r Dorsal Lamina. — The languets placed along the dorsal line are large and triangular,
but rather broader and blunter than usual.

Tht Tentacles are branched, and are large compared to the size of the body. They
are sixteen in number, and are of two sizes placed long and short alternately.

They are not much branched, and contain numerous and large calcareous spicules of
the same form as those in the branchial sac. The branches are rather long and narrow.

A single specimen of this small species, slightly injured, was obtained off the east
coast of North America, south from Long Island. After the publication of the part of
my Preliminary Report in which this species was described as new under the name of
Culeolus suhmi, a MS. of Dr. R. von Willemces Suhm was placed in my hands, in which
a sketch and a brief description, under the name of Boltcuia jicrlata, n. sp., evidently
refer t«> this specimen. I have consequently substituted Suhni's specific name.

Station 44. May 2, 1873 ; hit. 37° 25' N., long. 71° 40' W. ; depth, 1 700 fathoms;
bottom temperature, 1"7 C. ; grey ooze (a blue mud).

Culeolus moseleyi, Herdman (PL X. figs. 7-12 and PL XIII. figs. 3-4).

Culeolus moscl- i/i, Ilerdman, Preliminary Report, Proc. Roy. Soc. EJin., 1880-81, p. 87.

External Appearance. — This is a small species, but it has the body and the peduncle
both rather elongated. The general outline of the body is elongated pyriform, the anterior
being the narrower tapering end (PI. X. fig. 7). The outline is pretty regular, and

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

the body is somewhat compressed laterally. The anterior extremity is very narrow and
attenuated, being more produced, and tapering more gradually than in any of the other
species. The posterior end is broad and slightly rounded, having a truncated appearance.
It forms a nearly straight line dorso-ventrally, and curves round sharply at the ends to
become continuous with the dorsal and ventral edges. These two edges are almost
equally curved. They diverge from the narrow anterior end for about half the length of
the body, at which point the greatest breadth (dorso-ventral) is attained. They then run
parallel for a short distance, and finally curve sharply and evenly into the ends of the
posterior extremity. The two sides are equally, but slightly convex.

The peduncle is rather long and thin, but stiff (PI. X. fig. 7). It is attached to
the attenuated anterior end of the body, and forms a continuous line with the dorsal
and ventral edges. It may be traced for a short distance along the ventral edge, partly
imbedded in the test. After leaving the test it runs for a short distance anteriorly, and
then curves round dorsally at nearly a right angle, and preserves a slightly undulated
course down to the base of attachment. At this point it is slightly expanded, elsewhere
it is of the same thickness throughout.

The branchial aperture (PI. X. fig. 7) is situated on the dorsal edge of the anterior
end, and is nearly one-fourth of the length of the body, from the point of attachment of
the peduncle. It is conspicuous but not prominent. It has the form of a transversely
elongated rather crescentic slit, having the concavity directed posteriorly (PL X. fig. 8),
and its anterior edge forming an angle in the middle so as to give the aperture a sub-
triangular form like that of Culeolus recumbens. The anterior and posterior lips are
not prominent and are scarcely marked. The opening is directed dorsally and anteriorly.

The atrial aperture lies in the centre of the large posterior end, and looks directly
posteriorly (PI. X. fig. 7). It is sessile but conspicuous, and is a large transverse, slightly
crescentic, slit, gaping slightly, and having no raised lips (PI. X. fig. 9). The edges are
dorsal and ventral.

The surface is even but very rough, being covered all over with conical and dome-
shaped papillae (PL X. figs. 7, 8 and 9). These papillae are larger than those scattered
over the test in any of the other species, but here they are not modified in any particular
region to form a band round the atrial aperture as in Culeolus murrayi, Culeolus recum-
bens, and Culeolus <perlatus. The surface of the peduncle is slightly roughened like that
of the last species.

The colour of the body is a pale yellowish-grey — the papillae having a decided yellow
tinge. The peduncle is darker, being of a greyish- brown colour.

The dimensions are as follows : —

Length of the borly (antero-posterior),

2 cm.

Breadth of the body (dorso-ventral),

1-2

Thickness of the body (lateral),

8 mm.

Length of the peduncle,

about 9 cm.

Thickness of the peduncle,

•75 mm.

REPORT ON THE TUNICATA. 119

The Test is rather stiff and thick — thicker than in tin- three last described species.
It is quite opaque. The outer surface is very rough, the papilla? heing larger than and
nearly as numerous as in Cuh-oltis j >,■)•/< it us. Tiny arc dome-shaped, or of a short conical
form.

The test between the papillse has a yellowish-grey tint, in some places hyaline, while,
the papillse are of an opaque yellow, thus adding greatly to the general yellow effect and
opacity of the body. There is no foreign matter adhering to the surface.

The surface of the peduncle is slightly uneven from the same cause as in the last
species. In this case, however, the trabecular are fewer in number, consequently the meshes
are much larger and are more irregular (PI. X. fig. 10). The dark brown trabecular are
distinctly visible to the eye, and the matrix between them is of a bluish-grey colour, and
semi-transparent.

The Mantle is thin, but the musculature is stronger than in the last three species.
The muscle bands are strong, and in some parts are distant, while in others they are
closely placed, forming a strong, but generally irregular, network.

Tlie Branchial Sac is delicate, and has several slight folds on each side. They
aii' similar to those in Culeolus perlatus, each having four or five internal longitudinal
bars, which, however, are rather more closely placed (PI. X. fig. 11, br.f.).

The transverse vessels are narrow and are all of the same size. The internal longitudinal
bars are wider, and, as in the last species, form the strongest part of the network.

The meshes are square and are moderately large. Here and there secondary sbghter
transverse vessels and fine longitudinal vessels (PI. X. fig. 11, l.t.) may be seen crossing
the meshes, but they are rare.

Calcareous spicules are present in the vessels as usual, chiefly in the internal
longitudinal bars. They are large and branched like those in the last species, and are
numerous.

The Endostyle. — This organ, as usual, may be divided into an outer clear edge on
each side, and a central, more opaque area (PI. XIII. fig. 3). The edge (u\e.) on each
side occupies about one-fourth of the entire width of the endostyle, and is transparent
and covered by a layer of tesselated epithelium distinctly nucleated. This edge is
bounded internally by a rather broad opaque yellowish-brown band (l.b.b.), which is
separated by a narrow clear area from a slightly broader but similar band (<■./*.".), divided
from its fellow of the opposite side by a narrow clear stripe. Consequently the central
area is traversed by four broad bands running longitudinallv, and separated by narrow
dear stripes. Calcareous spicules are plentiful, and are scattered over the entire
breadth of the organ, being present, however, in rather greater quantity in the central
area than in the clear edges. They are large and considerably branched (PI. XIII.
fig. 3, sp.).

The Dorsal Lamina. — As usual, this is represented by a scries of triangular languets.
They are rather small and pointed.

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

The Tentacles are small, and seem not to differ strikingly in size. They are very
delicate, and are very slightly branched, almost simple, having only occasional minute pinnae.
Calcareous spicules similar to those of the branchial sac are plentiful in the tentacles.

Tlie Dorsal Tubercle is rather large, and has more of the usual appearance than those
of Guleolus recumbens and Culeolus perlucidus. It is of a transversely ovate shape, with
the aperture turned towards the right side (PI. X. fig. 12). The anterior horn turns out-
wards and upwards, while the posterior horn, also turned outwards, is coiled in a close
spiral of one and a half turns. The peritubercular area is triangular and not large in
comparison with the size of the tubercle. The peripharyngeal bands forming its lateral
boundaries are straight (PI. X. fig. 12, p.p.).

The Nerve Ganglion. — The ganglion is large and of a bright yellow colour. It has an
oblong quadrangular shape (PI. XIII. fig. 4, n.g.), and gives off two large nerve trunks at
each end.

In the mantle covering the ganglion dorsally, there is a patch of branched calcareous
spicules, similar to those in the branchial sac. They are very numerous, and cross
and interlace, forming in one part of the patch a very dense reticulum (PI. XIII.
fig. 4, sp.).

The single specimen of this species is in a good state of preservation. It was obtained
in the centre of the Pacific Ocean, almost on the Equator.

Station 271. September G, 1875; kit. 0° 33' S., long. 151° 34' W. ; depth, 2425
fathoms; bottom temperature, 1° C. ; globigerina ooze.

Comparison of the Species of Culeolus.

As the six species of this genus differ in nearly all the minute details of structure, it
will be interesting to go over the more important organs, and point out the differences
and resemblances which they present in the different species.

External Appearance. — In respect to external appearance there is a strong general
resemblance between the species. They all consist of a more or less ovate body borne
on a long peduncle. In all, the a)iterior end of the body, where the peduncle is attached,
is narrower than the posterior end, and in none of them is there much lateral com-
pression.

In all the species the peduncle, after leaving the test, turns at a right angle — in two of
them (Culeolus recumbens and Culeolus perlucidus) ventrally, and in the other four
dorsally. Consequently, in all the long or antero-posterior axis lies at right angles to
the peduncle, and therefore in a more or less horizontal position. In Culeolus wyville-
thomsoni, and Culeolus perlucidus this axis comes to be inclined downwards and
posteriorly on account of the curvature of the peduncle, while in Culeolus recumbens
the peduncle is so flexible that it could not have supported the weight of the body, which
must, therefore, have rested on the bottom.

REPORT ON THE TUNICATA. 121

In the two larger species (Culeolus wyville-thomsoni and Culeolus murrayi) the
branchiaJ aperture has a clearly-defined triangular form, with the apex of the triangle
directed posteriorly. In the other four species the shape is more that of a transverse
slit, but there is a tendency in all of them towards a triangular form. This is most
clearly seen in Culeolus recumbens, where the anterior or ventral lip is straight, while the
posterior or dorsal is strongly arched, forming an angle in the middle, and in Culeolus
moseleyi where the slit is cresccntic — the apex here, however, being anterior.

In all the species the branchial aperture is situated on the dorsal side of the point of
attachment of the peduncle, and consequently in the four species in which the peduncle
turns dorsally the branchial aperture is to a certain extent hidden by it and looks more
or less downwards towards the bottom ; in Culeo/ns perlucidus, on the contrary.it is
directed upwards.

The atrial aperture is a transverse bilabiate slit in all, and is situated towards the pos-
terior end. In three species, Culeolus murrayi, Culeolus wyville-thomsoni, stud Culeolus
moseleyi, it is quite posterior, while in the other three it is a little dorsal in position.

In Culeolus iri/rille-tliomsoiii, the surface, though very uneven, is to the eye smooth ;
in the other species, however, it is rough from the presence of papillae or tufts projecting
from the surface of the test. In Culeolus perlucidus these are few in number and of small
size, but in the other four species they are larger, and in three of them, Culeolus murrayi,
< 'uleolus recumbens, and Culeolus perlatus, they are especially developed along a line
found the posterior end and surrounding the atrial aperture. Along this tract the
papillae are larger and more closely placed, so as to form a continuous band. Culeolus
moseleyi, finally, has the surface closely covered with papillae of moderate size, making it
equally rough all over.

Culeolus recumbens is the only species which has sand-grains and other foreign
matter adhering to the surface of the body and peduncle, and it may be accounted for in
this case by the position the body must have had, lying on the bottom on account of
the weakness of the peduncle.

The peduncle in all the species is thin but tough, smooth, and somewhat flexible
though stiffish, except in the case of Calculus recumbens, where, as above mentioned, it
i- weak and very flexible like a piece of string. In all, it is expanded slightly at the
lower end to form a base of attachment.

The Test. — In all the species the test is of a cartilaginous consistency, though, in
-nine ,,{' fchem, especially Culeolus recumbens and Culeolus perlucidus, it becomes mem-
branous, on account of its thinness.

The only notable peculiarities are in regard to the development and disposition of the
blood-vessels. In Culeolus murrayi they are feebly developed throughout the thickness
of the lest, but as compensation they expand at the outer surface into large closely placed
thin-walled chambers in communication with the large membranous hollow papillae. In
Culeolus wyville-thoinsoiii, on the other hand, vessels are numerous throughout the thick

122

THE VOYAGE OF H.M.S. CHALLENGE!*.

test, and terminal expansions on the outer surface are very rare. In different parts of the
test, however, usually deeply situated, there are large cavities or reservoirs full of yellowish-
brown blood-corpuscles, and appearing to the eye as minute brown dots scattered thickly
nver the test. In these species there are also found, in connection with the terminal twigs
of the vessels in the superficial layer, numbers of minute thin-walled finger-like processes
projecting beyond the surface of the test. They are found in the hollows and grooves on
the uneven surface, probably on account of the protection afforded to them in these spots.
These delicate processes doubtless represent the papillae of Culeolus murrayi.

In Culeolus perlucidus, the pouches or cavities filled with blood-corpuscles seen on the
inner surface of the test are undoubtedly prolongations from the blood-sinuses of the
mantle. No further development of the vascular system in the test was seen either in this
species or in Culeolus recumbens. In Culeolus moseleyi and Culeolus perlatus, of each of
which there are only single specimens, the test could not be examined.

The peduncle probably contains blood-vessels in all the species. In Culeolus murrain
and Culeolus recumbens the vessels are numerous, and form a network traversing the
peduncle. In Culeolus perlucidus there is a single central canal, apparently vascular.
In the remaining three species the peduncle could not be examined without injuring
the single specimens. In two of them, Culeolus moseleyi and Culeolus perlatus, a net-
work of brown bars is distinctly visible from the exterior traversing the substance of the
peduncle. These bars possibly indicate thickened or modified portions of the matrix
separating canals in which the blood-vessels lie, as seen in Culeolus murrayi.

The structure of the mantle is very similar in the six species.

The Branchial Sac. — This is much the most characteristic organ in the genus, and is
very similar in all the species.

Fia. 14. — Part of the Branchial Sac of Culeolus wyville-tlwmsoni, from the inside.
lr., large transverse vessel ; tr'., smallest size of transverse vessel ; i. I., internal longitudinal bar ; mh., mesh ; sp., spicula.

REPORT ON THE TUNICATA. 123

The arrangement found in Culeolus wyville-thomsoni is perhaps the most distinct.
Here the meshes are much smaller than in any of the other species, and three distinct
sizes of transverse vessels are present (fig. 14). In Culeolus murrayi there are two
sizes, arranged alternately. In the other four species the transverse vessels are apparently
all of equal calibre.

The number of folds in the branchial sac was only determined in two of the species,
Culeolus murrayi and Culeolus wyville-thomsoni, and in both it was six on each side.
In the other species there are several folds on each side, probably six also. The
simplest form of fold is that seen in Culeolus perlueidus, where it consists merely of one
additional bar running parallel with and attached to each internal longitudinal bar on
its inner surface. The irregular secondary transverse vessels and fine longitudinal vessels
found occasionally in Culeolus recumbens and Culeolus moscleyi are very interesting as
showing a tendency towards the formation of stigmata. This process has gone further in
Culeolus j>erlucidus, where the fine longitudinal vessels intermediate to the internal
longitudinal bars divide the meshes into spaces comparable with true stigmata.

With regard to the apparent absence of spicules in the branchial sac and endostyle
of Culeolus perlueidus, Dr. Theel informs me that in some of the Challenger Holothurids
the integument has been entirely, and in others partially, decalcified, in consequence
probably of some impurity in the spirit in which they were preserved. Possibly a
similar process has occurred in the case of this Ascidian.

The Endostyle was not examined in Culeolus perlatus. In all the other species,
ignoring the absence of spicules in Culeolus perlueidus, this organ is very similar. In
Culeolus murrayi, Culeolus ivyville-thomsoni, and Culeolus recumbens the greatest
development of spicules is in the outer clear edge, and in the last species they are confined
to that locality. In Culeolus moscleyi, however, though present in the clear edge also,
they are more plentiful over the central opaque area.

There is nothing worthy of remark in the languets along the dorsal edge of the
branchial sac.

The Tentacles. — The tentacles are very similar in all the species, and are of the
ordinary Cynthiad type. In some of the larger ones, however, especially in Culeolus
murrayi, one notices that peculiar puffing out of the lower or branchial membranous
surface of the tentacle so characteristic of the organ in the Molgulidse.1

In three of the species, Culeolus murrayi, Culeolus wycille-thomsoni, and Culeolus
perlatus, the number of tentacles is sixteen, and they are of two sizes, eight of each being
arranged alternately. In Culeolus murrayi, in addition to these, there are also a certain
number of much smaller ones of various sizes, and having no apparent symmetrical
arrangemeut. In Culeolus wyviUe-thomsoni one of the large tentacles situated in the
dorsal region is very much larger than any of the others. In Culeolus recumbens the

1 See H. de Lacaze-Duthiers, Les Ascidies Simples des cotes de France, Arch, de Zool. expex. et g£n., t. vi. p. 477.
Paris, 1877.

(ZOOL. CHALL. ESP.— fAUT xvii. — 1882.) R 17

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

tentacles are also of two sizes, arranged alternately, but here there are twelve of eaeh

si/e.

In ( 'ideal us ■perlucidus and Culeolus moseleyi the relative sizes and arrangements are
not so definite. In the latter species the tentacles are small, and are the simplest and
least branched forms found in the genus.

The Dorsal Tubercle. — This organ in Culeolus murrayi and Culeolus toyville-ihom-
soni has quite the ordinary structure, and resembles the simpler forms we usually find in
the Cynthiidse. In Culeolus moseleyi also the dorsal tubercle is not abnormal, having an
ovate form, an aperture, and two twisted horns.

In two of the species, however, Culeolus recumbens and Culeolus perlucidus the organ
is very different, and is apparently of a much simpler type. In both it takes the form of a
somewhat elhptical mass with a simple straight aperture — merely the opening of the canal
provided with thick lips, and not twisted or coiled in any way. In Culeolus perlatus I
was unable to make out the dorsal tubercle without cutting the unicpie specimen more
than I considered justifiable.

There is nothing notable about the nerve-ganglion. It occupies the usual position, is
of elongated form, and gives off nerve trunks at the branchial and atrial ends.

I was unable to make any observations on the condition of the neural gland. From
want of material I could not make a special object of this organ, and it was not noticed
incidentally along with any other parts. In Culeolus recumbens and Culeolus perlucidus,
however, where the region of the nerve-ganglion and the peritubercular area were carefully
examined, it cannot have any great development ; and it probably constitutes the mass
forming the back of the dorsal tubercle, in which case the canal leading from the gland to
the tubercle would be reduced to a minimum.

There is nothing worthy of special remark in the condition of the peripharyngeal
bands, the praebranchial zone, and the peritubercular area.

Hie Alimentary Canal. — The structure and course of the alimentary canal was
determined in those species of which there are more than a single specimen.

In all it is small relatively to the size of the body and compared with the branchial
sac ; and in all it is situated at the posterior end of the body and on the left side of the
branchial sac. In all the oesophagus is short, the stomach large and well defined, and
the intestine long and narrow, but here the general simdarity ends.

In Culeolus murrayi the anterior or intestinal end of the stomach is rather the
larger, while in Cideolus recumbens the oesophageal end is the larger. In both the wall
is pushed out into a number of csecal processes or diverticula. In Culeolus perlucidus
the stomach is more elongated, tapers towards both ends, and has no csecal processes.
Though the exact course of the intestine differs in the three species, yet in all it runs
for a short distance anteriorly along the ventral edge of the branchial sac, after leaving
the stomach, and then turns dorsally, up the left side, and finally runs back posteriorly
fco end near the atrial aperture.

REPORT ON THE TUNICATA. 125

In Culeolus recumbens the dorsal part of the intestine or rectum is short compared with
the ventral part next the stomach ; this is caused by the atrial aperture being situated on
the dorsal edge, and not at the posterior end of the body. In Culeolus mwrrayi, where
the atrial aperture is more posterior, the rectum is longer. In Culeolus perlucidus, where
the atrial aperture is not quite posterior, the great length of the rectum is caused by its
devious course.

The form and course of the alimentary canal in the genus are thus very similar to
what is found in the majority of Simple Ascidians, and may easily be derived from the
arrangement found in the genus Ascidia (fig. 15, left hand diagram) by twisting the
rectum round posteriorly, so as to allow the anus to follow the atrial aperture from the
anterior to the posterior end of the dorsal edge.

Ascidia. Cufrohtn.

Fig. 15. — Diagrams of Ascidia and Culeolus, seen from the right side, to show the course of the Alimentary Canal.

Br., branchial aperture ; At., atrial aperture ; ped., peduncle ; In., tentacles ; d.l., dorsal lamina ; ce.a., cesophageal aperture ;

St., stomach ; i., intestine ; a., anus ; 1, intestinal loop ; 2, rectal loop.

Thus the rectal loop, or second intestinal curve (2), concave anteriorly in Ascidia, is
entirely done away with in Culeolus (fig. 15, right hand diagram). In Culeolus
perlucidus there is a rudiment of it, as the rectum is long, and, after running rather
farther posteriorly and ventrally than the atrial aperture, has to curve up again dorsally,
so as to bring the anus near it. If we compare this arrangement with that found in a
species of Ascidia where the atrial aperture is placed far back on the dorsal edge, as in
Ascidia depressa, the difference will appear very slight.

The course of the intestine in Culeolus mwrrayi, where the atrial aperture is posterior
and the rectum runs straight towards it, is the simplest, and seems probably to have
been the archaic form. Culeolus perlucidus has the atrial aperture rather more dorsal in
position, and consequently there is a slight twist upwards in the terminal part of the
rectum. Ascidia is a still more modified form in which the atrial aperture is normally al
the anterior cud of the dorsal edge, and here we find the rectal loop fully developed and
the rectum running anteriorly in place of posteriorly as in Culeolus.

The Genitalia. The genital glands, like the intestine, could only be examined in the
three species of which there are more than single specimens.

126

THE VOYAGE OF H.M.S. CHALLENGER.

In all they are in the form of hermaphrodite masses projecting from the inner
surface of the wall of the peribranchial cavity, and developed on both sides. They are
near the posterior end and rather nearer the ventral than the dorsal edge, those on the
left side being in close relation to the rectum.

In Culeolus murrayi there are several quadrate genital masses on each side, more
on the right side than on the left. Each mass consists of a spherical spermarium
surrounded by masses of ova. The different spermaria are connected by a delicate vas
deferens, so that all on the one side of the branchial sac have a common opening.

In Culeolus perlucidus there is a single genital mass on each side, lying parallel with
the stomach, and having the excretory ducts directed posteriorly. In Culeolus recumbens
there are three genital masses on each side of the body, and each opens by a distinct ovi-
duct and vas deferens. In this species the rectum is distant from the stomach, and the
genital glands on the left side lie in the wide intestinal loop, while in Cideolus perlucidus
the rectum is in close contact with the stomach, the intestinal loop is narrow, and conse-
quently the genital mass lies outside on the dorsal edge of the rectum.

The species of Culeolus may be distinguished by characters taken from the condition
of the branchial sac and tentacles alone, as shown in the following table : —

Culeolus.

Transverse vessels all of

Transverse vessels of different
sizes.

2 internal longitudinal bars 4 internal longitudinal bars Transverse vessels of
upon a fold. upon a fold. two sizes.

Culeolus perlucidus.

Culeolus murrayi.

Transverse vessels of
three sizes.

Culeolus wyville-tlioms

Tentacles small, slightly branched,
all of much the same size.

Culeolus moseleyi.

Tentacles large, much branched, of two
sizes, placed alternately.

24 tentacles.

I
Culeolus recumbens.

16 tentacles.

I
Culeolus perlatus.

REPORT ON THE TUNICATA.

127

Fungulus, n. gen.
Body globular, borne on a short thick peduncle attached to the anterior end.

Branchial aperture triangular, atrial aperture bilabiate.
Test cartilaginous, but very thin, not modified on the peduncle.
Hrum-liio! Sac with several slight folds on each side ; meshes square, no stigmata.
Dorsal Lkiuuiii a plain membrane.
Tentacles compound.
Genitalia a single gland on each side.
This genus is formed for a single Ascidian, which was at first considered as a
Culeolus, but which seems to be sufficiently distinct to require a separate position. It
is abnormal amongst Bolteninse, as regards the condition of the peduncle, and on the
strength of this character alone might be placed in the sub-family Cynthinse, but it is
probably more correct to place it here beside Cuholus, with which its internal structure
shows it to have close affinities.

Fungulus cinereus, n. sp. (PI. XIII. figs. 7-10).

External Appearance. — This species is club-shaped, and consists of a rounded knob-
like body borne on a short thick peduncle. The body is globular, and not compressed
laterally. The anterior end is rather wide, is directed downwards, and becomes continuous
with the peduncle by its ventral edge. The posterior end is wide and rounded, especially
at its ventral extremity. The dorsal edge is long and straight, but the ventral is strongly
convex. The peduncle is continuous with the ventral edge of the anterior end ; it is
longer than the body, and about half as wide, and is attached by its lower extremity.

The apertures are distant, they are conspicuous, but scarcely projecting. The branchial
is at the dorsal edge of the anterior end, not far from the point of attachment of the
peduncle; it is slightly prominent, is rather large and open, and is surrounded by a circular
raised lip within which are three flat lobes leaving the aperture triangular ; it is directed
anteriorly and slightly dorsally. The atrial is close to the posterior end of the dorsal edge ;
it is sessile, and not so conspicuous as the branchial. The aperture is in the form of a
gaping transverse slit with anterior and posterior lips ; it is directed dorsally and slight! y
posteriorly.

The surface is even, but minutely roughened on the peduncle. The body is nearly
smooth, it is slightly wrinkled in parts, and a little incrusted with sand grains on the
left side.

The colour is dark grey with a slate-blue tinge in parts.

Length of the body, . . . . . 1-3 cm.

Breadth of the body,
Thickness of the body,
Length oi the peduncle,
Breadth of tin- peduncle,

1-2
11

la
•5

/ /'■ st is thin, but moderately tough, and is between cartilaginous and membranous

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

in appearance. Minute rather distant projections on the outer surface give it a finely
roughened appearance. The projections are slightly larger, and more numerous on the
lips of the apertures.

The peduncle is hollow, but has the cavity crossed by delicate trabecular formed by
prolongations of the thin test on each side. The matrix is homogeneous, but is traversed by
irregularly running delicate fibres. Small rounded protoplasts are scattered through it ;
but there are no bladder cells nor pigment corpuscles, and no vessels are visible. The outer
surface, especially of the papillary projections, is covered with adhering foreign particles,
diatoms, &c.

The Mantle is very thin, and adheres closely to the inner surface of the test. The
musculature is feeble, the bundles being narrow and distant ; they are of a light brown
colour, and form a wide-meshed delicate network.

The Branchial Sac is a wide-meshed coarse net with several folds on each side. The
transverse vessels are wide and all of one size. The internal longitudinal bars are strong,
and are only present on the folds, which are formed of three bars closely placed and united
by short transverse ducts. In each interspace between the folds, but not placed symmetri-
cally, there is a fine longitudinal vessel joining the transverse bars. The meshes formed
by the folds and the transverse vessels are square or slightly elongated transversely.
The internal longitudinal bars are cihated on the sides, but not on the internal thickened
edge.

The Endostyle is conspicuous. It is of a brown colour, and has prominent lips.

TJie Dorsal Lamina is a plain broad membrane.

TJie Tentacles are compound. They are large and considerably branched, but few in
number.

The Alimentary Canal lies on the left side of the branchial sac, towards the ventral
edge and posterior end. It is a long and narrow tube, with no distinct stomach.

The Genital Glands are two in number, one on each side of the mantle.

This is a most interesting form, on account of its evident relationship to Cideolus, as
shown by the shape and position of the apertures, the place of attachment of the peduncle
to the body, and especially in the structure of the branchial sac. The most striking-
difference from Cideolus, and in fact from all the other Bolteninae, lies in the peduncle,
which in the present species is evidently merely a short prolongation of the body (PI.
XIII. fig. 7), covered by test in the normal condition ; while in all the species of
Cideolus the structure of the test on the long thin peduncle is modified so as to give it
the appearance of being a distinct organ attached to the body. Otherwise the external
appearance is quite that of a Cideolus. The branchial aperture is anterior, just at the
dorsal side of the peduncle, while the atrial is nearly posterior (PL XIII. fig. 7).

The test is thin, and its outer surface is slightly papillated, while the lips of the trian-
gular branchial (PI. XIII. fig. 8) and bilabiate atrial apertures are rough, with rather larger

REPOKT UN THE Tl NICATA. 129

and more numerous papillae. In the small piece of test examined, no vessels were to be
seen. The mantle, like that of the smaller species of Culeolus, is thin, and the muscula-
ture is feeble but distinct.

The must striking point of resemblance, however, is in the structure of the branchial
sac (PL XIII. fig. 9). That organ lias here the same simple type hitherto found only
in Culeolus, and in Bathyoncus, one of the Styelime. The sac is especially like that of
Culeolus perlueidus, from which it differs chiefly in that there the fold is formed of
simply two internal longitudinal bars, while in the present species there are always three
( PI. XIII. fig. 9, or.f.) I have no1 been able to detect calcareous spicules in any part of the
sac. Cilia are present on the internal longitudinal bars, but seem to be confined to the sides,
being placed on the small cubical cells forming the lateral walls of the vessel, while
the columnar cells outhe free internal edge have none.

<r.a.

Fig. 16. — Diagrammatic lateral view of Fungvhu cinereus, showing the course of the Alimentary Canal.
Br., branchial aperture ; At., atrial aperture ; pal., peduncle ; br.s., branchial sac ; ce.a., oesophageal aperture ; >'., intestine ;

a., anus ; g., genital gland of left side.

I could discover no languets. A plain band, about twice the breadth of an internal
longitudinal bar, runs along the dorsal edge of the branchial sac, and appears to represent
the dorsal lamina, The endostyle is very distinct, but has no calcareous spicules. The
central area is about one-third of the entire breadth (PI. XIII. fig. 10), and is traversed
by three pairs of opaque brown bands (c.b.a., and l.b.h.) running longitudinally. One
■ >f the prominent edges in the piece examined has the blood vessels engorged with brown

I'l 1 corpuscles (PI. XIII. fig. 10, cap.), while the other edge is clear and transparent.

The tentacles are large and much branched. The exact number could not be made out,
but it is probably about eight.

The alimentary canal is undifferentiated into regions, and hangs freely in the peri-
branchial space, having no attachment (except by blood vessels) to the mantle. The
oesophageal aperture lies at the posterior end of the branchial sac (fig. 16, ce.a.), and
the tube has the following course It first runs ventrally and then anteriorly along the
ventral side of the branchial sac. It next turns dorsally ('•) and posteriorly and then
ventrally, so as to form a curve convex dorsally. It then turns posteriorly and finally
dorsally so as to form a second curve, with the concavity dorsal this time, and thus reaches

1130 THE VOYAGE OF H.M.S. CHALLENGER.

the neighbourhood of the posteriorly placed atrial aperture close to which the anus
(«.) opens.

There are two short sausage-shaped genital glands. The left one (fig. 16, #.),lies attached
to the inner surface of the mantle, in the second intestinal loop (open dorsally). The
gland on the right side is rather longer, and lies nearer the ventral edge and the posterior
end than the middle. Its short duct is directed posteriorly and dorsally.

One specimen of Fungulus cinereus was obtained in the Southern Ocean, between the
Cape of Good Hope and Kerguelen Island, at Station 147; December 30, 1873; lat.
46° 16' S., long. 4S° 27' E.; depth, 1600 fathoms; bottom temperature, 0°-S O; bottom,
globigerina ooze.

Sub-Family Cynthiisle.

Body attached, sessile or very shortly pedunculated. Branchial and atrial aper-
tures with four lobes each.

Test coriaceous, rarely cartilaginous, not covered with sand.

Branchial Sac with more than four folds upon each side.

Tentacles compound.
This sub-family includes the typical forms of the Cynthiidse — the genera Cynthia and
Microcosmus. It is clearly distinguished from the Styelinae by the structure of the
branchial sac and the tentacles, whde it differs from the Bolteninse in not having a
peduncle. The short stalk present in one or two species of Cynthia {e.g., Cynthia cerebri-
formis) is really merely the narrowed posterior end of the body.

Microcosmus, Heller.

Cynthia, Savigny, M^moires sur les Anim. sans Vertebras, pt. 2mo, fasc. 1, p. 90. 1816. In part.
Cynthia, Delle Chiaje, Memoria sulla Storia e Notomia degli Animali senza Vertebre del Regno di Napoli,

torn. iii. 1823-29. In part.
Microcosmus, Heller, Untersnch. ii. d. Tun. d. adriat. u. Mittelmeeres, Abth. 3, Wien. 1877, p. 3.
Cynthia, Traustedt, Oversigt over de fra Danmark, &c., Ascidiae Simplices, Kjobenhavn. 1880. In part.

Body attached, sessile, not incrusted with a continuous coating of sand. Aper-

tures both four-lobed.
Test coriaceous, thin but tough.

Branchial Sac with more than four folds upon each side.
Dorsal Lamina a plain untoothed membrane.
Tentacles compound.
Intestine forming a narrow loop.

Heller (1877) distinguished Microcosmus from Cynthia on account of the plain-edged
dorsal lamina and the narrow intestinal loop. In the third part of the Preliminary Beport,
published in 1880, I expressed a certain amount of doubt as to the sufficiency of the
characters on which this genus was founded.

REPORT ON THE TUNICATA. 131

T am now of opinion, however, that as these characters, and especially the condition of
the dorsal lamina, are apparently constant and are easily applied, and as the two groups
of species (Microcosmus and Cynthia) seem fairly distinct, it is, if not absolutely necessary,
at least convenient to retain both generic terms.

The Challenger expedition added two new species to the nine or ten already known,
and found a large specimen of Microcosmus polymorphus, the common Mediterranean
species, in a new locality.

Microcosmus helleri, Herdman (PI. XIV. figs. 1-4).

Microcosmus helleri, Herdman, Prelim. Rep., Proe. Roy. Soc. Edin., 1880-81, p. 54.

External Appearance. — The body is longish ellipsoidal in shape, with a projection at
the anterior end ; it is scarcely compressed laterally. It is attached by a small area at the
posterior end of the ventral edge. The anterior end narrows rapidly into the truncated
conical branchial projection ; the posterior end is broad and rounded, and the dorsal and
ventral edges are nearly straight and parallel. The branchial aperture is at the anterior
end of the dorsal edge; it is terminal, on a large projection directed anteriorly and slightly
ventrally. The atrial aperture is on the dorsal edge, about two-thirds or three-fifths of the
way down, and placed on a hemispherical projection. It is not so prominent as the
branchial aperture, and is directed dorsally and a little posteriorly.

The surface is wrinkled and roughened, but not covered with excrescences ; the
branchial and atrial projections are much corrugated and thickened ; a few Zoophytes,
Polyzoa. &c, are found adhering, especially on the left side and posterior end.

The colour is a dull gamboge yellow, with a little reddish-brown at the posterior end
and on the left side.

Length of the body, 8 cm. ; breadth of the body, 4 cm.

The Test is leathery; it is rather thin, except at the area of attachment and on the
siphons. The inner surface is white with a few yellowish-brown patches.

The Mantle is strongly muscular on the right side and the dorsal part of the left; it is
membranous on the ventral part. The musculature is strong and regular.

The muscular band at the base of the branchial siphon, and just above the circle of
tentacles, bears four large bluntly conical processes projecting into the lumen of the tube.

The Branchial Sac has six folds on each side. The alternate transverse vessels arc
larger than the intermediate ones, and about every fifteenth larger transverse vessel is very
much wider than the others. The internal longitudinal bars are numerous. There are
eight only on the folds and about twelve in the interspaces, each of which has six wide
and six narrow rows of meshes. The largest meshes contain each six to eisdit stigmata.

Tie Dorsal Lamina is a plain membrane.

The Tentacles are compound, they are twenty in number, and of two sizes placed
large and small alternately.

(ZOOL. CH^LL. EXP. — PART XVH. 1882.) R 18

13-2 THE VOYAGE OF H.M.S. CHALLENGER.

The Dorsal Tubercle is broadly cordate, with both horns rolled inwards.

In external appearance this species is not unlike Microcosmus polymorphus, Heller,
but it is scarcely so rough and irregular in shape. The apertures are both distinct and
prominent (PI. XIV. fig. 1), especially the branchial, and the test in their neighbour-
hood is considerably thickened and corrugated, elsewhere it is rather thin. The mantle
is strong, and muscle bands are greatly developed on the right side and on the dorsal region
of the left. In the branchial siphon, above (anterior to) the circlet of tentacles, four large
bluntly conical processes project from the lower edge of the sphincter muscle into the
lumen of the tube, and form a sort of imperfect diaphragm.

Another point in which this species differs from Microcosmus polymorphic, is the
branchial sac, which has only six folds on each side. The folds are rather narrow compared
with the interspaces (PL XIV. fig. 2). The transverse vessels are strong, and are usually
alternately larger and smaller (the latter are very frequently traversed by the stigmata).
Sometimes, however, there are three sizes occurring alternately (PL XIV. fig. 4, tr., tr.'
and tr."). Besides this, about every fifteenth vessel is enormously enlarged (PL XIV.
fig. 3, tr.x.), and forms a broad band traversing the sac.

There are eight or nine internal longitudinal bars on the upper side of the fold, so that
the figure (PL XIV. fig. 4, br.f.), only shows half of the fold. The meshes in the inter-
space between the folds are of two distinct sizes, and there are six of each kind. The
larger ones are overlapped by the fold, and about three of them are usually hidden
(PL XIV. fig. 2).

One specimen of this species wras obtained in Torres Strait, between Australia
and New Guinea, at Station 188 ; September 10, 1874 ; lat. 9° 59' S.; long. 139° 42' E. ;
depth, 28 fathoms ; bottom muddy.

Microcosrmis propinquus, Herdman (PL XIV. figs. 5 and 6).

Microcosmus propitiquus, Herdinan, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 55.

External Appearance. — The body is oblong-ovate or almost triangular in shape, and is
compressed laterally. It is attached by the posterior two-fifths of the ventral edge. The
anterior end is narrow, and terminates in the branchial projection ; the dorsal and ventral
edges slope backwards to the broad and rounded posterior end. The branchial aperture
is terminal, and is situated on a large projection turned ventrally and slightly to the left
side. The atrial aperture is also prominent ; it is on the dorsal edge, three-fourths of the
way from the anterior to the posterior end, and is directed dorsally.

The surface is wrinkled and minutely grooved, but not covered with excrescences ; it is
somewhat corrugated around the apertures, and has a few foreign bodies adhering.

The colour is pale yellow, with a reddish-brown tinge here and there.

Length of the body, 7 "5 cm.; breadth of the body, 5 cm.

RETORT ON THE TUNICATA. 133

The Test is leathery, it is tough but rather thin. The inner surface is white and
glistening.

The Mantle is strongly muscular on the right side, but membranous over the
viscera. A narrow membrane projects into the branchial siphon above the tentacular
circlet ; it is sbghtly crenated, but does not bear large conical processes as in Micro-
cosmus helleri.

The Branchial Sac has seven folds on each side. The transverse vessels are all of one
size. The internal longitudinal bars are strong and numerous ; there are about six on the
fold and the same number in the interspaces. The meshes are transversely elongated,
and contain each about twelve stigmata ; generally a fine transverse vessel divides the
mesh into two.

The Dorsal Lamina is not broad, but rather thick ; the edge is plain.

Tlie Endostyle is very broad.

The Tentacles are about twenty in number. There are six large, six small, and some
intermediate very minute ones which are not present in all the interspaces.

Tlie Dorsal Tubercle is irregularly cordate, and has both ends turned inwards.

This species is nearly allied to Microcosmus helleri, and is not unlike it in external
appearance (compare figs. 1 and 5 in PI. XIV.). In the details of its anatomy, however, it
differs considerably, the principal points being that the present species has fourteen folds
in the branchial sac, while Microcosmus helleri has only twelve, and that the diaphragm
in the branchial siphon is different.

The single specimen was attached by the posterior part of its ventral edge to the
interior of a bivalve shell (PL XIV. fig. 5). The branchial aperture is conspicuous, and
is directed ventrally. The test covering the siphon is not seamed and corrugated like
that of Microcosmus helleri; over the rest of the body it is considerably wrinkled. The
mantle is well developed, and forms a slight diaphragm at the base of the branchial
siphon, which, however, does not form large processes, as in the case of Microcosmus
helleri. The branchial sac (PL XIV. fig. 6) has wide meshes between the folds, contain-
ing each ten to fifteen stigmata. Most of the meshes are divided by a narrow horizontal
membrane (tr.), the wider transverse vessels (tr.) are all of one size.

One specimen was obtained off East Moncoeur Island, Bass Strait, at Station 162,
April 2, 1874; depth, 38 to 40 fathoms; bottom sandy.

Microcosmus polymorphus, Heller (PI. XIV. figs. 7 and 8).

Microcosmus polymorphus, Heller, TJntersueh. u. d. Tun. <l adriat. Mm-., Al.th. 3. p. 0.
Microcosmus polymorphus, Herdnian, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 55.
(?) Ascidia papillosa, Cams, Beitrage zur Aiiatomie und Physiologie der Seescheiden, Meckel's
Aichiv., BcL ii. p. 569, pis. vii. and viii., 1816.

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

The large specimen in the Challenger collection, which I have referred to this species
differs somewhat externally from Heller's original description of Microcosmus polymorphus.
It is smoother and less covered with excrescences. In internal structure, however, it
agrees well, and I think there can be no doubt that it is the same species.

The branchial sac is yellow, and has seven large folds on each side. The difference in
the proportion between the folds and the interspaces in this species and in Microcosmus
hclleri may be seen by comparing figs. 7 and 2 on PL XIV. There are about ten internal
longitudinal bars on each side of the fold, and five or six in the interspace ; they are very
stout. The meshes contain from ten to fourteen stigmata each (PL XIV. fig. 8).

The tentacles are about twenty in number, compound, and of two sizes, placed large
and small alternately. The dorsal lamina is smooth-edged.

This seems to be the species described in 1816, by Dr. C. G. Carus, in his " Beitrage
zur Anatomie und Physiologie der Seescheiden," under the name of Ascidia papillosa.
His fig. 2 on PL VII. is especially like the present species, and on the other hand his fig. 1
on PL VIII. shows a large rounded projection at the base of the branchial siphon : the other
figures correspond very fairly with Microcosmus polymorphus.

One large specimen of this species, 11 cm. in length and 7 cm. in breadth, was
obtained along with Microcosmus propinquus, off East Moncceur Island, Bass Strait, at
Station 162, April 2, 1874; depth, 38 to 40 fathoms; bottom sandy.

Cynthia, Savigny.

Ascidia, Linnasus, 0. F. Muller, Lamarck, Cuvier, &c. In part.

Cynthia, Savigny, Menioires sur les Animaux sans Vertebres, pt. 2me, faso. 1, 1816. In part.

Hahxynthia, Verrill, Bull. U. S. Nat. Museum, No. 15, p. 147, 1879. In part.

Cynthia, Heller, Untersueh. ii. d. Tun. d. adriat. u. Mittelm., Abth. 3, p. 9, 1877.

Cynthia, Traustedt, Oversigt over de fra Danmark, &c, Ascidia? Simplices, 1880. In part.

Body attached, sessile or very shortly stalked, rarely incrusted with sand.

Branchial and atrial apertures both four-lobed.
Test coriaceous, rarely cartilaginous.

Mantle well developed, usually with a strong musculature.
Branchial Sac with six to twelve longitudinal folds upon each side.
Dorsal Lamina with the free margin toothed.
Tentacles always compound.
Intestine forming rather a wide loop.

The genus Cynthia was founded by Savigny in 1816, for sessile Simple Ascidians with
a coriaceous test, but at that time, and for long afterwards, it included all the other
genera of the Cynthiidse, with the exception of Boltenia. Of the groups into which
Savigny divided his Cynthia, the Cynthia? Simplices most nearly correspond to the present

REPORT ON THE TUNICATA. 135

restricted genus. Macleay, in 1823, separated Styela from Savigny's genus Cynthia, but
this division was not accepted by other writers, and the term Cynthia continued to be
used in the old sense until Heller, in 1877,1 defined the four genera — Microcosmus, Styela,
Polycarpa and Cynthia, using the latter in the restricted sense in which it is employed
here.

A genus Cynthia was founded by Thompson subsequently to Savigny's ': Memoires,"
for a small group of Schizopodous Crustaceans allied to Mysis. Even although Cynthia
is not now employed strictly as denned by Savigny, still it includes the most typical forms
of Savigny's genus, and as it is generally recognised and accepted, there is no doubt that it
ought to remain. There is more chance of confusion arising from the substitution of
Halocynthia, as proposed by Verrill, than from the employment of the same generic name
in a totally distinct class of animals.

Traustedt 2 admits the distinctness of Styela from Cynthia, but does not, however,
accept Heller's Microcosmus. Hence Traustedt employs Cynthia in rather a wider sense
than that in which it is used here.

The characters of Cynthia are those of the sub-family, with the exception of the
features which distinguish Microcosmus. The body may vary greatly in shape, but is
always attached, is very rarely stalked at all, and has never a long peduncle. The
branchial and atrial apertures are both either scpiare or surrounded by four lobes. The
test is usually leathery; it may be thin but is always tough. Occasionally it is soft and
cartilaginous, but never so much so as in the genus Ascidia. There are no hairs developed
upon the outer surface,3 and there is almost never an incrusting coat of sand. The
mantle is usually very thick, and has the muscle bands strongly developed, forming two or
three distinct layers.

The branchial sac is thrown into a series of strongly-marked folds, usually six or seven
on each side, but more may be present (there are eleven upon each side in Cynfln'o
complanata, and twelve upon each side in Cynthia grandis).

The condition of the dorsal lamina is one of the characters upon the strength of
which Heller separated Microcosmus from Cynthia. In the latter genus the dorsal
lamina has its free edge bordered by a series of short languets, while in Microcosmus it is
a plain membrane. The tentacles are compound, and they do not differ appreciably from
those of Microcosmus, or of the Bolteninae.

The alimentary canal is usually large, and the stomach is distinct ; the intestine forms
a wide loop. The genitalia have various forms, but are developed upon both sides of the
body, and are usually simple or lobed elongated masses.

The Challenger collection contains nine species of Cynthia, eight of which are new

1 Untersuch. ii. d. Tun. d. adriat. und Mittelm., Abth. 3, Th. 1, Denkschr k. A_kad. Wis* nseh. Wien, Bd. xxxiv.

2 Oversigt over de fra Danmark, &c, Aseidia' Simpliees, viil. Miil.l. Nat. I'm-., Kjobi-nliavn, ls80.

3 Except upon Cynthia hispida and the anterior end of Cynthia formosa.

i:;i;

THE VOYAGE OF H.M.S. CHALLENGER.

to science. They may be distinguished by characters taken from the branchial sac alone,
as shown by the following table : —

Cynthia.

Branchial sac with 6 folds
upon each side.

!

S or 9 internal longitudinal 5 or 6 internal longitudinal
bars upon a fold. bars upon a fold.

|

9 or 10 stigmata

in a mesh.

I .
Cynthia

formosa.

6 stigmata
in a mesh.

!

Cynthia
cerebriformis.

Branchial sac with more than
6 folds upon each side.

with with with with

7 folds. 8 folds. 9 folds. 11 folds.

I I I

Cynthia Cynthia Cynthia

pallida, hispida. complanata.

About 9 internal

longitudinal bars

on a fold.

6 to 8 stigmata
in a mesh.

I
Cynthia fissa.

4 stigmata Cynthia
in a mesh, irregularis.

Cynthia arenosa.

About 4 internal

longitudinal bars

on a fold.

I
Cynthia

papietensis.

Cynthia cerebriformis, Herdman (PL XV. figs. 5-7).

Cynthia cerebriformis, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 57.

External Appearance. — The -body is irregularly pyriform; the anterior end is wide
and is bent over greatly to the right side, which is concave, while the left is prominent
and convex. The posterior end is drawn out into a short stalk, tapering towards the point
of attachment. The apertures are not distant, both are terminal, and placed at the anterior
edge of the right side, slightly projecting, and directed to the right and a little anteriorly.
The surface is suleated all over, so as to closely resemble the convoluted surface of a
brain ; four large convolutions lead up to each aperture. The posterior end and the stalk
are wrinkled, but not sidcated like the rest. The colour is dirty yellowish-white, becom-
ing brown on the stalk.

Length of the body, 6 "5 cm.; breadth of the body, 4-7 cm.

The Test is thick, and very stiff and solid ; it is white on section and on the inner
surface.

The Mantle is very thick, and is muscular at the anterior end. The branchial
siphon is short and wide ; the atrial is narrower, but nearly twice as long.

The Branchial Sac has six folds on each side. The internal longitudinal bars are
numerous, there are about nine on a fold, and the same number in the interspace. The
transverse vessels are all of the same size. The meshes are occasionally divided by
narrow horizontal membranes, and contain each six stigmata.

REPORT ON THE TTJNICATA. 137

The Dorml Lamina is represented by a series of closely placed, stout, tapering,
languets.

Tie Tentacles are branched; they are twenty in number, ten large and ten small,
placed alternately.

TJie Dorsal Tubercle is rather large ; it is elliptical in outline, and is placed with its
transverse axis directed anteriorly and posteriorly, the opening being at the right .side ;
both horns are turned in and form moderately large spirals.

This is a very striking species, and although an ordinary Cynthia in its structure, is
quite unlike any other species in external appearance (PI. XV. fig. 5). The anterior
end is large and rounded and bears the two apertures, while the posterior is prolonged
backwards into a short stalk by which the body is fixed. The entire surface is raised
into convolutions which, taken along with the yellowish white colour, suggested the
specific name cerebriformis. The apertures lie upon the right side, which is concave,
while the left is strongly convex. It looks as if the anterior end, bearing both apertures,
had been forcibly bent over, so as to form the front of the right side. The openings are
very distinct (PL XV. fig. 5), and each is surrounded by four prominent lobes.

The branchial sac (PL XV. fig. 6) is that of a typical Cynthia. The folds are large,
and have each a number of internal longitudinal bars, which are closely crowded at the
crest of the fold. The transverse vessels are all of one size and are rather strong. The
meshes are slightly elongated transversely, and are usually not divided ; they contain
from five to seven stigmata each.

The dorsal tubercle is large, and lies in rather a shallow peritubercular area (PL XV.
fig. 7). The opening between the spirals is directed to the right side ; each spiral is
composed of about two turns, but the anterior is considerably the larger one.

The oesophageal aperture lies very far forwards in the branchial sac, and there is no
distinct stomach. The digestive tube runs first posteriorly and then ventrally in irregular
curves, so as to reach the ventral edge of the body, where it turns sharply round pos-
teriorly, and then sweeps round the lower end of the body and turns anteriorly at the
dorsal edge so as to reach the neighbourhood of the atrial aperture. The general course
is similar to that found in the genus Corella amongst the Ascidiidse.

One specimen of this curious species was obtained at Port Jackson, Australia, June
3, 1874 ; depth, 30 to 35 fathoms ; bottom, rock.

Cynthia fissa, Herdman (PL XV. figs. 8-11).

Cynthia fissa, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 58.

External Appearance. — The shape is ovate, with a deep cleft at the anterior end of the
dorsal edge extending nearly half way through the body ; it is slightly flattened laterally,
and is attached by the posterior end and nearly the posterior half of the left side. The

1:n the voyage of h.m.s. challenger.

apertures are prominent ; they are placed at the extremities of the two projections formed
by the cleft ; the branchial projection is terminal, the atrial is on the dorsal edge, fully
half way from the anterior to the posterior end, and is not so long as the branchial.

The surface is very irregular, and is much wrinkled and rough ; on the right side the
chief wrinkles run transversely. The colour is yellowish-brown.

Length of the body, 2 cm. ; breadth of the body, 1 -6 cm.

The Test is strong and stiff; it is white on the inner surface.

The Mantle is thick and moderately muscular.

The Branchial Sac has six folds on each side. There are six internal longitudinal
bars on each side of a fold, and three in the interspace. The transverse vessels are wide,
and are of two sizes placed alternately. The meshes, which are transversely elongated,
contain each six to eight oval stigmata, and are sometimes divided by a narrow hori-
zontal membrane.

T7te Dorsal Lamina has the free edge terminated by a series of tentacular languets.

The Tentacles are simply pinnate, and are about twelve in number.

The Dorsal Tubercle is large and irregularly oblong, and the aperture is anterior ;
both horns are turned to the left. It lies in a small, but deeply cup-shaped perituber-
cular area.

This curious little species looks, on account of the prominent anteriorly placed
branchial and atrial apertures, as if the anterior end of the body had been deeply cleft
(PI. XV. fig. 8). In this respect, and in the markings on the surface, the species is rather
like Cynthia dura, Heller,1 from which it differs in the number of tentacles, the shape of
the dorsal tubercle and several other particulars.

Cynthia Jissa is also like Cynthia irregularis in some respects. The external
appearances are not very dissimilar, and the branchial sacs are very much alike in their
minute details (compare PL XV. fig. 9, and PI. XVI. fig. 11), but they differ in their
coarser anatomy, as Cynthia irregularis has fourteen folds while Cynthia Jissa has only
twelve. The dorsal tubercles of the two species are entirely different.

The tentacles in Cynthia Jissa are scarcely compound (PL XV. fig. 11). They
look like the tentacles of a Styela, with a series of small buds projecting from each side.
The dorsal tubercle is of the simple form very commonly found in Ascidia, and is
deeply cup-shaped, with both horns turned to the left.

Several specimens were found adhering to the test of Microcosmus polymorphous, from
Station 162, April 2, 1874 ; off East Moncceur Island, Bass Strait; 38 to 40 fathoms ;
bottom sandy.

1 Untersuclmngi/n ii. d. Tunic, des adriatischen Meeres, Abtli. 3, p. 11, pi. iii. fig. 1.

REPORT ON THE TUNICATA. 139

Cynthia formosa, Hcrdman (PI. XVI. figs. 1-5).

Cynthia formosa, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 58.

External Appearance. — This species has a spherical body and a narrow stalk.
The posterior end of the body is rounded, and the anterior is rather flatter; the
dorsal edge is slightly more convex than the ventral. The stalk is about as long as
the body, it is twisted and narrow, but expands slightly at the lower end where it is
attached. The apertures are both at the anterior end ; they are not distant, and are
prominent.

The surface is smooth on the posterior half of the body, and is covered with fine silky
spines on the anterior half ; these increase in size towards the anterior end, and culminate
in sheaves of long bristles, which surround and hide the apertures. The colour is grey.

Length of the body, T5 cm., breadth of the body, 13 cm. ; length of the stalk, 1/6 cm.

The Test is thin but tough ; it is semi-transparent on the posterior half of the body
only.

The Mantle is thin but muscular ; the muscle bands form a close net-work.

The Branchial Sac has six folds upon each side. The internal longitudinal bars
are ribbon-like, and there are about eight on a fold and four in the interspaces. The
transverse vessels are rather wide and are all of one size. The meshes are transversely
elongated, and are divided usually by three narrow membranes ; they contain each nine
or ten stigmata.

Tlie Dorsal Lamina consists of a series of small closely-placed languets, borne on the
edge of a broad lamina.

The Tentacles are large and much branched, and are about twelve in number.
Between these are a series of much smaller but also compound tentacles, placed usually
two between each pair of large ones, and these again are separated by very minute simple
proj ections.

TJie Dorsal Tubercle is simple ; it is transversely elliptical, with the opening anterior,
and the horns turned inwards.

This is a most elegant little species, and seemed at first sight, with its delicate peduncle
and the coating of bristles upon the anterior end of the body, as if it might require to be
separated generically from its congeners. It is, however, in internal structure quite a
typical Cynthia, but it is the only one which has what may properly be called a peduncle
(PI. XVI. fig. 1). Here that organ really merits its name ; it is thin and stalk-like, and
fully as long as the body. The coating of hairs is very peculiar. It is only present upon
the anterior end of the body, and around the terminally placed apertures it is exaggerated
to form two clumps of bristles which terminate the body, anteriorly. The test upon the
posterior half of the body is thin and semi-transparent and has no hairs.

(ZOOL. CHALL. EXP. — PAKT XVII. — 1882.) R 19

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

There is little noteworthy about the branchial sac. The vessels are strong and the
meshes are large, but each is divided transversely into three or four areas by delicate
membranes (PI. XVI. fig. 2). Figure 3 on Plate XVI. shows a small portion of the
branchial sac, from the external surface, where the vessels are irregular. Several stigmata
are apparently absent in two adjacent rows, leaving wide longitudinal ducts connecting
the transverse vessels.

The dorsal lamina is a wide membrane, with a series of teeth or short languets placed
along its free margin (PL XVI. fig. 4, /.). The tentacles are very numerous (PL XVI.
fig. 5). There are twelve very large ones, with a row of branched pinnae along each side
(tn.). Between each pair of these larger tentacles there are two smaller branched ones,
very like the pinnse of the larger ones, and separated from each other and from the larger
tentacles by four or five small conical projections which may be considered as simple
tentacles, so that there are three orders altogether, two of them compound and one
simple ; and there are twelve of the largest or first order, twenty-four of the second, and
about 180 of the third (PL XVI. fig. 5). The prsebranchial zone is broad and
transparent, allowing the longitudinal muscle bands to show through distinctly.

The peritubercular area is very small, and does not enclose the dorsal tubercle, which
is simple and somewhat reniform. The aperture is anterior, and the horns are simply
turned inwards and not coiled (PL XVI. fig. 5, d.t.).

One specimen of this species was obtained in Torres Strait, between Australia and
New Guinea ; depth, 3 to 1 1 fathoms.

Cynthia arenosa, Herdman (PL XVI. figs. 6-9).

Cynthia arenosa, Herdman, Prelim. Rep., Proc Roy. Soc. Edin., 1880-81, p. 59.

External Appearance. — The body is irregularly ovate or sub-triangular in shape ; it
is elongated transversely, and not compressed laterally. The posterior end is broad and
rather flat, the anterior is narrow ; the dorsal and ventral edges are convex ; and the body
is not attached. The apertures are both at the anterior end ; they are inconspicuous, are
placed close together, and are cross-slit.

The surface is entirely covered, with the exception of the siphons, by a close layer of
sand grains. The colour is grey.

Length of the body, 1 "5 cm. ; breadth of the body, 1 cm.

TJie Test is thin, but very stiff on account of the imbedded sand.

The Mantle is thin but strong; the muscle bands are well developed.

T/te Branchial Sac has six folds on each side. There are about five internal longi-
tudinal bars on each fold, and the same number in the interspace. The transverse vessels
are usually of the same size, but here and there, at distant intervals, very much wider
ones occur, which equal at least an entire row of stigmata in breadth. The meshes are

REPORT ON THE TUNICATA. HI

square, and contain about four stigmata each. They are always divided transversely by
a delicate membrane.

The Dorsal Lamina is formed of a series of small tentacular languets.

TJie Tentacles arc compound, they are few, and are placed long and short alternately.

The Dorsal Tubercle is simple; it is rudely cordate in outline, with the opening
anterior, and both horns turned inwards.

This curious little species is very unlike a Cynthia in external appearance. It is
irregularly ovate in shape, is apparently unattached, and has the entire body covered with
a close coating of sand grains (PL XVI. fig. 6). The inconspicuous apertures are not
lobed but are cross-slit, or have each the appearance of four short slits radiating from a
central point.

The branchial sac has six folds upon each side, but they are not very large, and have
only five internal longitudinal bars on the outer slope of each. The occasional very wide
transverse vessels are curious (PL XVI. fig. 7, tr.). Each looks exactly as if a complete
row of stigmata had been obliterated, especially as the delicate transverse membranes
stretch along them exactly as they do over the ordinary meshes. This branchial sac is a
little irregular in some other respects. Here and there we find one of the ordinary trans-
verse vessels (PL XVI. fig. 7, tr.') interrupted for a short distance, and two meshes thrown
into one, thus producing a few very long stigmata.

The dorsal lamina is formed of languets alone (PL XVI. fig, 7, /.). There is no mem-
brane uniting their bases. They are placed one opposite each transverse vessel, and
one opposite each horizontal membrane.

The dorsal tubercle is simple, and is more like the tubercle of an Ascidia than of
a Cynthia. The aperture is anterior, and the horns are turned inwards but are not coiled
(PL XVI. fig. 8, al.t.). The peritubercular area is shallow.

The tentacles are compound, and are few in number. They are of two sizes, and are
very similar to those of the next species, Cynthia irregularis.

Several specimens of this little species were obtained in Torres Strait, between
Australia and New Guinea, at Station 186; September 8, 1874; lat. 10° 30' S., long.
142° 18' E. ; depth, 1 to 8 fathoms ; bottom, coral sand.

Cynthia irregularis, Herdman (PL XVI. figs. 10-12).

Cynthia irregularis, Herdman, Prelim. Pep., Proe. Roy. Soc. Etlin., 1880-81, p. GO.

External Appearance. — The shape is very irregular. The body is attached to a
fragment of a shell by the right side near the dorsal edge and half way up from the
posterior end. The posterior end is small, and nearly flat; the anterior end is broad,
and is deeply cleft between the large divergent siphons, on the extremities of which the

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

apertures are placed. The branchial aperture is at the ventral edge of the anterior end;
it is prominent, and is turned ventrally and a little to the left. The atrial aperture is at
the dorsal edge of the anterior end ; it is not quite so prominent as the branchial, and is
turned dorsally and a little to the left.

The surface is very uneven, and is deeply wrinkled and rather rough. The colour is
yellow and dark brown.

Length of the body, 4 "5 cm. ; breadth of the body, 3 cm.

The Test is thin, except at the posterior end, where it is thickened ; it is tough and
opaque, and is white on section and on the inner surface.

The Mantle is rather strong and muscular.

Tlie Branchial Sac has the folds very slight and distant ; there are seven on each side.
The transverse vessels are mostly wide but irregular. The internal longitudinal bars are
numerous ; there are about nine on a fold and eight in the interspace, which has four
wide and four narrow rows of meshes. The meshes contain each about four short oval
stigmata, and are often divided by narrow horizontal membranes.

The Dorsal Lamina is formed of a series of narrow tentacular languets.

Tlie Tentacles are compound, they are very small, and consist of twelve larger ones,
with either one or two very minute ones between each pair of larger.

The Dorsal Tubercle is very large, but irregular ; it is broken up into a number of
curved pieces.

This species is very irregular in external appearance (PL XVI. fig. 10), and has a good
deal the look of a Microcosmus, with its creased and furrowed, thin but tough and stiff
test, of a yellow and brownish colour.

The branchial sac (PL XVI. fig. 11), is also rather irregular. There are fourteen folds,
but they are not very wide although each has a considerable number of internal longi-
tudinal bars upon its surface. The space between each pair of folds has usually eight rows
of meshes, four of which are wide and four narrow (PL XVI. fig. 11).

The dorsal tubercle is the most remarkable feature in this species (PL XVI. fig. 12).
It occupies the greater part of a triangular and rather deep peritubercular area, and is
present in the form of eight or nine distinct apertures of irregular shajjes, and each
bounded by a raised lip. These apertures are arranged in the form of a deeply cup-shaped
curve, and look as if they were the remains of a tubercle of the ordinary type, with the
aperture anterior and both ends bent slightly to the left, which had had its originally
single curved slit broken up into the series of separate apertures.

One specimen of this species was found at Port Jackson, Australia ; depth, 2 to 1 0
fathoms.

REPORT ON THE TUNICATA. 1 13

Cynthia 'pallida, Heller (PL XVII. figs. 17-21).

Cynthia pallida, Heller, Beitrage zui nahern Kenntnisa der Tunicaten, p. 14, Taf. iii. figa 17,

18 (Sitzb. d. k. Akad. d. Wiss., Bd. Ixxvii. Abth. 1, 1878)'.
Cynthia pallida, Herdman, Prelim. Hep., Proc. Roy. Soc. Edin., 1880-81, p. 60.

The external appearance of this species has been fully described by Heller, and the
Challenger specimens agree well with that description. The branchial sac has eight folds
ivpon each side. One specimen has nine. There arc six internal longitudinal liars upon the
side of a fold, and only three in the interspace. The transverse vessels are of two sizes
placed alternately (PI. XVII. fig. 17, tr. and lr.'). The meshes are square or slight lv
elongated transversely; they contain each six or seven stigmata, and are divided l>\ a
narrow horizontal membrane (h.'m.'). As noticed by Heller, there are curious elongated
and fusiform calcareous spicules in the branchial sac (PI. XVII. fig. 17, sp.) and mantle
of this species, and smaller ones are present in the test. When Heller described this
peculiarity in 1878, it was, I believe, the first time such a thing had been noticed. Two
of the new species of Cynthia discovered by the Challenger expedition {Cynthia
complanata and Cynthia papietensis) show similar spicules in the test, mantle, and
branchial sac.

In the present species, the spicules of the branchial sac are chiefly in the wider transverse
vessels, and the internal longitudinal bars. They are elongated, slender, and pointed at
both ends. In the mantle (PI. XVII. fig. 18, sp.) they are more crowded, and are shorter
and stouter. When enlarged sufficiently, it is seen that they are minutely echinated all
over (PI. XVII. figs. 19 and 20), and that the pointed spines lie all in one direction, and
are arranged in closely placed transverse rows.

The dorsal lamina is in the form of a series of long tapering languets, united at their
bases by a narrow membrane wThich, like the vessels of the branchial sac, contains elongated
fusiform spicules (PL XVII. fig. 21). The tentacles are of two sizes, eighteen larger and
eighteen smaller being placed alternately.

The dorsal tubercle is small, and is usually transversely ovate in shape. In one
specimen examined both horns were coiled inwards, while in another one born turned in
and the other out, forming spiral coils.

In the third part of the Preliminary Report, some small specimens from Tahiti were
included under this species. 1 have since determined that they are distinct, and they
will be described below under the name of Cynthia papietensis.

Of the specimens of Cynthia pallida in the collection, one is from Simon's Bay, Cape of
Good Hope ; depth, 10 to 20 fathoms ; and two are from Kandavu, Fiji Islands.

Cynthia papietensis, n. sp. (PL XVII. figs. 10-1G).

External Appearance. — The body is irregularly ovate or elliptical in shape: it is trans-
versely elongated, and compressed laterally. The posterior end is wide and rounded ; t he

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

anterior is also wide, and is flattened or slightly concave in the middle between the aper-
tures. The dorsal and ventral edges are short and strongly convex, and the body is
attached slightly by the left side and the posterior end. The apertures are both on the
wide anterior extremity; they are moderately distant, slightly projecting, large, and
four-lobed.

The surface is even but slightly roughened, and has a few shell fragments, &c,
adhering here and there. The colour is a warm yellowish-brown.

Length of the body (antero-posterior), 1*5 cm. ; breadth of the body (dorso-ventral),
2-3 cm.

The Test is cartilaginous, but thin and soft ; it is semi-transparent, and is well
supplied with blood-vessels with enlarged terminal knobs, and containing numerous short
rod-like echinated spicules in their walls.

Tlie Mantle is thin, and of a light brown colour. The musculature is feeble but
distinct. It contains very delicate elongated fusiform spicules.

The Branchial Sac has seven folds on each side. There are four internal longitudinal
bars on the fold, and two in the space between the folds. The transverse vessels are all
of much the same size, and delicate fusiform calcareous spicules are present in abundance
in their walls. The meshes are square or elongated transversely, and are divided by a
delicate membrane. They each contain about six stigmata.

The Dorsal Lamina is represented by a series of rather small and closely placed
tentacular languets.

The Tentacles are not large. There are fifteen larger and fifteen smaller compound
ones placed alternately, and in addition there are about thirty minute simple processes,
which alternate with the branched tentacles.

The Dorsal Tubercle is small and simple, ovate in form, and placed at the bottom of a
triangular peritubercular area ; the aperture is anterior and minute ; the horns nearly
meet, but are not coiled.

This little species is closely allied to Cynthia pallida, Heller, with which I classed it
provisionally in the Third Preliminary Report (see Proc. Eoy. Soc. Edin., 1880-81,
p. Gl); the two species differ, however, in several particulars. According to Heller,1
Cynthia pallida is also found at Tahiti.

The two specimens from 20 fathoms differ slightly in external appearance (PI.
XVII. figs. 10 and 11) from the other five. They are not elongated transversely, and
the atrial aperture is more dorsal in position (fig. 10). In colour also they differ,
being milk-white in place of yellowish-brown. At first I was inclined to consider them as
a distinct species, but as a detailed examination has revealed no structural differences,
it is probable that they are merely individual variations, or at most a local variety.

1 Beitruge zur niihern Kenntniss Jer Tunicaten, Sitzb. dor k. Akad. der Wksensch., Bd. lxxvii., 1878, p. 15.

REPORT ON THE TUNICATA. 145

The dimensions given in the description arc those of the large specimen figured
(PL XVII. fig. 11) from 10 fathoms. The rest of the specimens are much smaller, and
are about the size of the specimen figured from 20 fathoms (PL XVII. fig. 10).

The test contains numerous light brown blood-vessels, with terminal knobs (PL
XVII. fig. 14), and also minute rod-like spicules, with slightly enlarged ends and
transverse bands of minute echinations (fig. 15).

In a slide mounted by Mr. Murray during the expedition, and labelled "varia from
Papiete Harbour," there is a squeezed specimen of a small Ascidian, which in all proba-
bility belongs to this species. Nothing can be made out in it except the test, which,
however, shows the same structure as that of Cynthia pajnetensi.s, and contains exactly
similar blood-vessels and spicules.

The mantle is thin, but contains distinct brown muscle bands, and has numerous very
graceful fusiform spicules, tapering to fine points and minutely echinated in transverse
bands.

The branchial sac is like that of Cynthia pallida in most respects, but has only
fourteen folds. The transverse vessels are also apparently all of the same size, and the
meshes are not elongated transversely (PL XVII. fig. 12). The delicate fusiform
calcareous spicules (fig. 13) are found chiefly in the transverse vessels, and are very
similar to those in Cynthia pallida.

The languets (PL XVII. fig. 12, I.) are small, and very closely placed. The tentacles
(PL XVII. fig. 16) consist of three sets, two of which are compound, while the third set,
alternating with the others, is simple. The peritubercular area is regularly triangular,
and is rather deep, the small dorsal tubercle being entirely included in it (PL XVII.
fig. 12, d.t). The intestinal loop is wide.

There are seven specimens of this species in the collection, all from Papiete Harbour,
Tahiti, Society Islands, September 28, 1875. Five of them are labelled "from 10
fathoms," and the other two, " from 20 fathoms."

Cynthia complanata, Herdman (PL XVII. figs. 1-9).

Cynthia complanata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 62.

External Appearance. — The body is elongated, oblong in shape, pointed at the anterior
end, and flattened laterally; the dorsal edge is straight or slightly concave, the ventral is
convex ; the posterior end is wider than the anterior, but is narrow. The body is attached
by the ventral edge of the posterior end. The branchial aperture is terminal, quad-
rangular, tubular and wide ; the atrial is on the dorsal edge, one-third of the way down
from the branchial aperture to the posterior end ; it is slightly projecting, and is also
quadrangular and wide.

The surface is irregular but smooth, and is slightly creased. The colour is a dirty white.

Length of the body, 5 '6 cm.; breadth of the body, 27 cm.

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

The Test is soft and cartilaginous. It varies greatly in thickness, as it is thin on the
anterior half, and then hecornes thicker, while the posterior third is a solid mass of test
suhstance.

The Mantle is thin; the musculature is rather feeble; the siphons are very wide.
There are long, thin calcareous spicules found in the mantle.

TJie Branchial Sac has eleven folds on each side. There are eight internal longi-
tudinal bars on a fold, and four in the interspace. The transverse vessels are mostly of
the same size, but here and there a much larger one occurs. The meshes are slightly
elongated transversely, and contain each about five stigmata ; they are generally divided
by delicate horizontal membranes.

The Dorsal Lamina is formed of short blunt membranous languets.

The Tentacles are branched ; there are nine large and nine small placed alternately,
and about eighteen very minute intermediate ones.

Tlie Dorsal Tubercle. — The general outline is nearly circular, but considerably con
voluted. Both homs are turned inwards, and slightly coiled.

This curious species has very much the appearance of an Ascidia, except that both
the apertures are more or less square (PL XVII. fig. 1). The test is cartilaginous, and
is very thick and solid at the posterior end. It contains quantities of short rod-like
calcareous spicules (PI. XVII. figs. 2 and 3). The spicules in the mantle (PI. XVII. fig. 4)
are like those found in Cynthia pallida, Heller, but are longer and thinner. They lie in
the interior of long membranous tubes or sheaths (PI. XVII. figs. 4, 5, and 6) which run
in zig-zags in all directions through the mantle. The spicules seem to fit the sheaths
exactly (fig. 6), and the echinations are placed in regular transverse rows.

The branchial sac has a large number of folds (22), and they are all well developed
and have a number of internal longitudinal bars. The interspaces between the folds
(PI. XVII. fig. 7) are rather narrow, and have only four rows of meshes.

Occasionally very wide transverse vessels are found (PI. XVII. fig. 7), but the others
are all of one size. Small fusiform and curved spicules are found scattered chiefly through
the transverse vessels. Two of them are represented more enlarged in PL XVII. fig. 8,
to show the arrangement of the spines in regular transverse rows. The curiously con-
voluted dorsal tubercle is shown in PL XVII. fig. 9.

One specimen of this species was found at Port Jackson, Australia ; depth, 6 fathoms.

Cynthia hisjrida, Herdman (PL XV. figs. 1-4).

Cynthia hispida, Herdmau, Prelim. Rep., Proc. Roy. Soc. EdLn., 1880-81, p. 61.

External Appearance. — The body is ovate or irregularly circular in shape ; it is flat-
tened laterally, and is nearly as broad as long ; the dorsal and ventral edges are strongly
convex ; the anterior end is broadish, and straight, and the body is attached by the

REPORT ON THE TUNICATA. 147

rather narrow posterior end. The apertures are both a1 the anterior end, are moder-
ately far apart, and are placed on short dome-like projections, the ends of which are con-
spicuously four-cleft and covered with strong echinated hairs, which fringe the apertures.
The branchial is directed anteriorly, and the atrial dorsally.

The surface is more or less wrinkled, and closely covered with a short down of prickly
hairs, which occasionally, at the posterior end and most markedly around the apertui
increase in size, and form large branched bristles. The colour is dull brown, rather
lighter around the apertures.

Length of the body, G"6 cm. ; breadth of the body, 5 '6 cm.

The Test is not thick, but is leathery and tough ; it is smooth and glistening on the
inner surface.

The Mantle is thick, and the musculature is very strong and close, especially on the
siphons.

Tlie Branchial Sac has nine folds upon each side ; the ventral folds, or those next the
endostyle on each side, are very slight. The alternate transverse vessels are wider than
the intermediate ones. The internal longitudinal bars are numerous, there are about
twelve on a fold, and six to eight in the interspaces. The meshes are small and contain
each about four stigmata.

The Dorsal Lamina is formed of a double series of very small languets.

The Tentacles are compound; there are about fourteen, and they are all nearly of
the same length.

TJie Dorsal Tubercle is small, but very prominent ; it is situated on a hemispherical
projection, and is elongated transversely ; both horns are coiled inwards.

There are two specimens of this species in the collection, both from Bass Strait. The
larger specimen has the surface considerably more wrinkled and the apertures more
prominent than is the case with the other. Both are attached by their posterior ends to
the interior of bivalve shells. The apertures are very conspicuous, being placed upon
dome-shaped projections, terminated by clumps of strong branched hairs (PI. XV.
fio\ 1). The surface is strongly wrinkled, and more or less clothed with short hairs.
The test is leathery and tough, and the mantle is thick and has its musculature well
developed.

The branchial sac has eighteen folds, each of which has a Large number of internal
longitudinal bars (PI. XV. fig. 2, hr.f)

The dorsal lamina is peculiar (PI. XV. fig. 3, /. and /.')• In addition to the usual series
of triangular languets (/.), there is a second series of similar but rather smaller and more
numerous processes (/.') running parallel with the first series, and separated from it
by a shallow groove. The dorsal tubercle is small but prominent (PI. XV. fig. 4). It
is simple and symmetrical, both horns being coiled inwards.

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) K -*-1

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

Two specimens of this large species were obtained off East Moncceur Island, Bass
Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sand.

Sub-family Styelin.e.

Body attached, sessile, rarely incrusted with sand. Branchial and atrial apertures

either four-lobed or cross-slit.
Test usually coriaceous, rarely cartilaginous.
Branchial Sac with four or less than four folds upon each side.
Tentacles simple, unbranched.

This section of the Cynthiidse represents the Cynthise Styelse and Cynthise Pandocias
of Savigny's system, and corresponds to the genus Styela alone as used by Macleay,
Fleming, and Traustedt, with the addition of Pelonaia, and the new Challenger genus
Bathyoncus. It is a very distinct sub-family, and can be clearly distinguished from both
the Bolteninas and the Cynthinse by two important characters : — (l), the branchial sac has
never more than eight longitudinal folds, four upon each side ; and (2), the tentacles are
always simple.

Savigny recognised these characters in both his third and fourth tribes of Cynthise, — the
Styela? and Pandocise, and Macleay, who in 1823 formed Savigny's tribes into genera,
distinguished those with only eight folds and unbranched tentacles from Cynthia and
Caesira, which had a greater number of folds and possessed compound tentacles. But
both these writers went on to sub-divide the group further according to the condition of
the genital organs. Thus Savigny distinguished the Cynthise Pandocise from the Cynthise
Styelse on account of the presence in the former of a single ovary placed in the intestinal
loop. E. Hertwig1 has, however, shown that Savigny was mistaken as to the nature of the
body which he called the ovary, and probably the Pandocise agree with the Styelaa in
having genital glands upon both sides of the body.

Macleay formed three genera, — Styela, with at least one ovary on each side of the
body ; Pandocia, with a single ovary in the intestinal loop ; and Dendrodoa, with a single
ovary upon the opposite side of the body. Pandocia was probably founded from Savigny's
mistaken account of the Cynthise Pandocise, and Dendrodoa should, I consider, be merged
in Styela. Various modifications of the genital glands occur among the species of this
genus, and I think they can scarcely be relied upon as furnishing generic characters.

The genus Pelonaia, discovered and described by Forbes and Goodsir in 1840, and
investigated since by M'Intosh, Kupffer and Traustedt, seems to me to fall naturally into
this group. I have lately had an opportunity of dissecting Pelonaia corrugata, and it
appears to be closely allied to Styela, and certainly does not require a distinct family or
sub-family for itself.

1 JenaischeZeitsclirift, Ed. viii. p. 96.

REPORT ON THE TUNICATA. 149

Heller in 1877, 1 distinguished Potycarpa from Styela, on account of the condition of
the intestinal loop, and of the genital glands. This separation has not been accepted by
Traustedt, but, although Styela and Potycarpa are undoubtedly very closely allied, I find
it convenient, on account of the large number of species in both genera, to recognise the
distinction until some species turns up which unites the characters of the two groups, and
cannot therefore be placed in either. Consequently, with the addition of the new genus
Baihyoncus, discovered by the Challenger expedition, I recognise four genera in the
Styelinse, and distinguish them briefly as follows : —

Styelix^e.

Branchial sac normal. Branchial sac with no stigmata

in the meshes.

Xo folds in the branchial sac. Branchial sac folded. Bathyoncus.

I .
Pelonaia.

! I

Genitalia as simple Genitalia in the form of numerous

or lobed tubes. small bodies.

! I

Styela. Potycarpa.

Styela, Macleay.

Ascidia, Linnaeus, Sys. Nat., Edn. 12. 1766. In part.

Astidia, 0. F. Muller, Zool. Dan. Prod. 1776. In part.

Cynthia, Savigny, Mem. sur les Anim. sans Vert l't. ii. fasc. 1. 1S16. In part.

Styela, Macleay, Anat. Obserr. on the Tunicata. 1823.

Pandocia, Fleming, British Animals. 1828.

Cynthia, van Beneden, Eecherches sur les Ascidies. 1846. In part.

Cynthia, Forbes and Hanley, Brit. Moll., vol. i. 1853. In part.

Styela, Hancock, Anat. and Phys. of Tunicata, Journ. Linn. Soc. 1868. In part.

Cynthia, Kupffer, Jahresber. der Commiss., &c. 1875. In part.

Styela, Heller, Untersuchuugen ii. d. Tun. d. adriat. Meeres., Abth. 3. 1877.

Styela, Traustedt, ( Iversigt ever de fra Danmark, &<■., Aseidise Simplices. 18S0. In part

Body attached, sessile or almost so, rarely incrusted with sand. Branchial and

atrial apertures either four-lobed or cross-slit
Test usually thin but leathery, rarely thick and cartilaginous.
Bronchial Soc with four or less than four folds upon each side.
Tentacles always simple.
Intestine forming a narrow loop
Genitalia in the form of one or more simple, lobed, or branched tubular bodies

1 Untersuchungen ii. d. Tunicaten d. adriat. Meeri a., Abth. :;. p. 19.

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

Although Savigny in his " Memoires " introduced the name Styela, Macleay was, as

far as I am aware, the first to use it as a generic term. This was in 1823, but the genus
was not accepted by subsequent writers, and the species of Styela were included in Cynthia
until 1868, when Hancock made use of the word " Styela" in a generic sense, and 1874,
when Heller returned to the original spelling, and defined the genus Styela as it is
employed here. Kupffer (" Jahresber. der Commiss., &c," 1875) does not recognise any
of the sub-divisions of Cynthia, and Traustedt accepts Styela, not in Heller's sense, but
as including Polycarpa.

Styela is distinguished from Pelonaia and Baihyoncus very clearly by the struc-
ture of the branchial sac. It is more difficult to separate it from Polycarpa, but as I
have said above (page 149), it is convenient to give generic names to the two groups of
species, until we find a connecting link. Heller gave two characteristics by which they
differ, — (1), the course of the intestine, which in Styela forms a narrow loop, while in Poly-
carpa it takes a wide, open curve ; and (2), the genitalia, which are found in Styela as one,
two or more, but never many, long simple or branched organs, while in Polycarpa they
form a large number of generally small and rounded bodies scattered over the inside of
the mantle upon both sides of the body, and called " polycarps " by Heller.

dl.

Fig. 17. — Diagrammatic transvers section of the Branchial Sac of Slyel".
I., II., III., IV. br.f., the branchial folds ; d.l., the dorsal lamina ; en., the eudostyle ; mh., one of the meshes.

The branchial sac is found in various conditions in the genus Styela. In typical forms
it has eight well-marked folds, four upon each side (fig. 17, I., II., III., IV". br.f.), and
a greater number is never present ; but many species have less than eight. The fold
nearest to the endostyle on each side appears first to become slighter, less of a true fold,
and more of a mere crowding together of the internal longitudinal bars, and then finally
disappears. In Styela grossularia there is only one recognisable fold in the branchial

REPORT ON THE TUN H 'ATA. 151

sac, placed in the dorsal region of the right side, but usually there are indications of the
positions of more or fewer, usually of all seven, of the missing folds.1

In several of the new Challenger species (e.g., Styela flava and Styela oblonga)
the folds are absent as such, but are represented by eight longitudinal tracts, four upon
each side, along which the internal longitudinal liars are very numerous, and are much
more closely placed than in other regions of the sac. There can be no doubt that these
art: merely the folds in a rudimentary condition.

It has been necessary to modify somewhat Heller's definition of the genus, as in one
of the newly discovered species {Styela byihia) the dorsal lamina is found in the form of
languets. In most species of the genus, however, the dorsal lamina has, as Heller says, a
smooth edge.

The Challenger expedition obtained only oue known species (Styela gyrosa), the other
eleven were new to science.

Styela bythia, Herdman (PI. XVIII. figs. 1 and 6-8).

Styela bythia, Herdman, Prelim. Rep., Proe. Roy. Soc. Edin., 1880-81, p. 63.

External Appearance. — The body is between cubical and hemispherical in shape,
and it is scarcely flattened laterally. The anterior end is broad and obtuse. The dorsal
and ventral edges slope backwards and slightly outwards, and the body is attached by a
wide posterior end, sbghtly expanded at the margin. The apertures are sessde, incon-
spicuous and four-cleft ; the branchial is at the ventral, and the atrial at the dorsal end
of the anterior extremity.

The surface of the test is flat, but rough, especially at the anterior end.

The colour is dark brown, paler towards the posterior end.

Length of the body, 2 cm.; breadth of the body, 1 cm.

Tlie Test is thick ; it is very stiff, but rather brittle, and is white on section and on
the inner surface.

Tlie Mantle is reddish-brown. It is moderately thick, and is closely united to the
test.

The Branchial Sac has four folds upon each side. There is a considerable space on
each side between the endostyle and the most ventral fold. The transverse vessels are all
of one size. The internal longitudinal bars are extremely numerous, and are much
crumpled. The meshes are small and elongated antero-posteriorly ; each contains one or
two stigmata only, and is divided transversely by a delicate bar.

Tlie Dorsal Lamina is in the form of a series of short languets.

This is a very interesting species, as it presents a combination of characters not
previously known, and requiring an alteration in the definition of the genus.

1 See Herdman, On Individual Variation in Simple Ascidians, Trans. Lit Phil. Soc, Liverpool, for 1882.

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

Heller, in his diagnosis of Styela, states that the dorsal lamina has a smooth edge ;
but this species, which is undoubtedly a Styela in all its other characters, has a series of
short tapering languets along the dorsal line of the sac. Another new species (Styela
Jlava) has the dorsal lamina ribbed transversely, and slightly pectinated at the margin,
evidently a condition intermediate between that seen in Styela bythia and that found in
other members of the genus. Hence I had no hesitation in changing the characters of
the genus slightly, so as to admit of the reception of Styela bythia.

It is a compact, irregularly hemispherical species, and was dredged from 2600 fathoms,
attached to a manganese nodule, along with a specimen of Styela squamosa (PI.
XVIII. fig. 1. The lower specimen on the nodule is Styela bythia). The test is thick
and stiff, but rather brittle. It adheres closely to the mantle below, but when detached
shows a white inner surface.

The branchial sac (Pi. XVIII. fig. 6) looks rather thick and opaque. This appearance
is caused by the large number of internal longitudinal bars present. These are
broad and ribbon-like, and are so closely placed that the meshes between them usually
contain only one or sometimes two stigmata each (PI. XVIII. fig. 6). Otherwise the
branchial sac has no very notable features. The transverse vessels are all of the same size,
the meshes arc small and particularly narrow, and are all divided transversely and sym-
metrically by narrow membranes. Figure 7 on Plate XVIII. shows a small portion of the
sac from the outside and more highly magnified. The outline of the stigma is rather
irregular, and no cilia could be discovered in any part of the sac which was examined.

The languets (PL XVIII. fig. 8, /.) are short but stout, and spring from a narrow,
transversely ribbed membrane (</./.) forming the basal part of the dorsal lamina.

One specimen of this interesting species was dredged to the south of Australia, a1
Station 160; March 13, 1874; lat. 42° 42' S., long. 134° 10' E.; depth, 2G00 fathoms;
bottom temperature, 0°-2 C. ; bottom, red clay.

Styela squamosa, Hcrdman (PL XVIII. figs. 1-5).

Styela squamosa, Herdmaa, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 66.

External Appearance. — The body is roughly hemispherical, and is slightly compressed
laterally. The anterior end is very large, and rises somewhat towards its ventral
extremity; the ventral edge is nearly straight, while the dorsal is gently convex. The
body is attached by the wide posterior end, and the margin is slightly expanded. The
apertures are sessile, distant and inconspicuous. The branchial is at the ventral end, and
the atrial at the dorsal end of the anterior extremity.

The surface is smooth but scaly. The colour is creamy white and slightly yellow in parts.

Length of the body, 2 cm.; breadth of the body, 1*5 cm.

'Ihe Test is thick and solid, but soft.

Tlie Mantle is very thin, and adheres slightly to the test.

REPORT ON THE TUNICATA. 153

The Branchial Sac has two distinct folds upon each side near the dorsal edge,
and one or two more indistinct ones ventrally. The transverse vessels are all of one
size. The internal longitudinal bars are numerous. The meshes are slightly elongated
antero-posteriorly, contain each four or five stigmata, and are divided transversely here
and there by a membrane.

Tlie Dorsal Lamina is plain, and has no ribs nor teeth.

Tlie Tentacles are larger and smaller alternately. The larger ones are short and
stout.

The Dorsal Tubercle is a simple elliptical tubercle, with no visible markings.

This species (PL XVIII. fig. 1, the upper specimen) was obtained, along with Styela
bythia, from 2600 fathoms. Although the two species are not unlike in external appear-
ance, they differ greatly in their internal structure. Styela bythia has four well-marked
folds upon each side of the branchial sac, while in Styela squamosa only two are distinct
upon each side, the others being in a rudimentary state.

Then again the internal longitudinal bars in Styela squamosa, through broad and flat
as in Styela bythia, are not nearly so numerous as in that species (compare figs. 2 and 6
on PL XVIIL), and consequently the meshes are not so narrow, and usually contain four
or five stigmata in place of one or two. On the folds, however, they are of course more
closely placed, and there the meshes are more nearly of the size found in Styela bythia
(PL XVIIL fig. 4, br.f.). The meshes next the dorsal lamina contain each eight to ten
stigmata (PL XVIIL fig. 5).

The dorsal lamina also differs from that of the last species, as it is a plain
membrane with no ribs or other markings, and with no marginal teeth. (PL XVIIL
fig. 5, d. I). The tentacles (PL XVIIL fig. 3) are of two sizes, but both are small.

This species was obtained along with the last at Station 160 ; March 13, 1874 ; lat.
42° 42' S., long. 134° 10' E.; depth, 2600 fathoms ; bottom temperature, 0°"2 C; bottom,
red clay.

Styela grandis, Herdman (PL XIX. figs. 1 and 2).

Styela grandis, Herdman, Prelim. Rep., Proc. Roj'. Soc. Edin., 1880-81, p. 67.

External Appearance.— -The shape is irregularly pyriform, the anterior end being-
large and somewhat globular, whfle the posterior narrows into a short thick stalk, by
which the animal is attached. The ventral edge is straight or slightly concave ; the dorsal
is long, and strongly convex. The branchial aperture is a little to the ventral edge of the
anterior end, and is directed ventrally ; the atrial is on the dorsal edge, about two-thirds
of the way from the anterior to the posterior end, and is directed dorsally and slightly
anteriorly. Both apertures are sessile; they are not very distinctly lobed, but are
conspicuous.

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

The surface is irregular, but not rough ; towards the base it is much corrugated
transversely. The rest of the surface is more or less seamed and wrinkled. The colour
is a dirty white, becoming slightly darker towards the base.

Length of the body, 9-5 cm. ; breadth of the body, G cm.

The Test is thin and soft, but fairly strong.

TJie Mantle is very delicate, and is closely united to the inner surface of the test.
The musculature consists chiefly of a number of fine bundles of fibres running longi-
tudinally.

The Branchial Sac has four folds upon each side, and the most dorsal one on each
side is placed very close to the dorsal lamina. There are three wide internal longitudinal
bars on each side of a fold, and about six in the interspace. The alternate transverse
vessels are wider than the intermediate ones. The meshes are immensely elongated
transversely, and contain each about twenty stigmata.

Tlic Dorsal Lamina is a rather wide and perfectly plain membrane, having no ribs nor
teeth.

The Tentacles are simple ; there are twenty long with occasional small inter-
mediate ones.

The Dorsal Tubercle is heart-shaped, and both horns are turned inwards.

This is a large species, probably the largest species of Styela yet known, and it has
more the appearance of an Ascidia than of one of the Cynthiidse (PL XIX. fig. 1).
The apertures are very peculiar ; the branchial looks as if it had eight lobes and the atrial
about six (the numbers characteristic of the genus Ascidia), but in reality there are only
four principal lobes, and the others are merely small projections or folds lying between.
The stalk is clearly the slightly narrowed posterior end of the animal, by which it is
attached. This region is considerably seamed transversely.

The test is rather thin and soft, considering the size of the body, and is closely attached
to the delicate mantle lying below it.

The branchial sac has the usual eight folds, but they are not large, and have compara-
tively few internal longitudinal bars. As a result the meshes are. very wide (PL XIX.
fig. 2), and contain in the spaces between the folds as many as twenty stigmata. Most
of the transverse vessels are slight ; they are much smaller than the internal longitudinal
bars, and are alternately a little larger and a little smaller. Here and there, however, at
considerable distances, a much wider transverse vessel occurs (PL XIX. fig. 2, near the
top of the figure). All of these vessels have wide horizontal membranes attached to
their inner surfaces (PL XIX. fig. 2, h.m.).

The tentacles are simple and are of two sizes. There are twenty of the larger size,
and a smaller number of shorter ones which only occur in occasional spaces.

Two specimens of this large species were dredged in the Antarctic Ocean, to the south of

REPORT ON THE TUNICATA. 155

Kerguelen Island, at Station 150; February 2, 1874; lat. 52° 4' S., long. 71° 22' E.;
depth, 150 fathoms; bottom temperature, 1°'8 C. ; bottom, rock.

Styela gyrosa, Heller.

(?) Cynthia rrmiru.ta, Philippi, Miiller's Arcbiv, 1843.

Styela gyrosa, Keller, Uutersuch. ii. d. Tuiiioaten d. adriat. Mceres., Abth. 3, p. 15, 1877.

This large and apparently widely distributed species was found by the Challenger
expedition at Port Jackson in considerable quantity. There are some large specimens of
it from the same locality in the Liverpool Free Public Museum. They were dredged
and brought home by Mr. Patterson.

As Heller (loc. cit.) has lately given a long description of the Mediterranean specimens,
and as the Australian ones seem to correspond in all particulars, little remains to be
said here. The Challenger specimens are even more massed together into pseudo-colonies
than Heller's seem to have been, and occasionally half-a-dozen or more individuals are
found united by the fusion of their tests into a rounded clump, placed upon an irregularly
twisted peduncle, nine or ten centimetres in length.

A number of specimens were dredged in 6 fathoms of water at Port Jackson,
Australia.

Styela convexa, Herdman (PL XIX. figs. 3-4).

Styela convexa, Herdman, Prelim. Eep., Proc. Roy. Soc. Edin., 1880-81, p. 69.

External Appearance. — The body is rudely hemispherical, or bluntly conical in shape,
and is not flattened laterally. The anterior end and the sides are convex ; the posterior
end is large, and is attached to a stone, and slightly expanded at the edge. The branchial
aperture is terminal, and is placed rather to the ventral side of the middle of the anterior
end, but forms its most prominent point; the atrial aperture is moderately distant, at
the dorsal edge of the anterior end; both are sessile and inconspicuous.

The surface is moderately smooth, and is finely creased in all directions, especially
round the apertures. The colour is a dull yellowish-brown, but lighter on the margins of
the posterior end.

Length of the body, 2 cm.; breadth of the body (dorso-ventral), 2*6 cm.

The Test is thin, but very tough; it is white on section.

The Mantle is closely united to the test, and has the musculature fine but close.

The Branchial Sac has four folds upon each side. There are aboul eighl internal
longitudinal bars upon a fold, and the same number in the interspaces. The meshes
are elongated antero-posteriorly ; each contains about three stigmata, and is divided
transversely by a narrow horizontal membrane.

The Dorsal Lamina is slightly crimped but plain; the edge is even.

(ZOOL. CHALL. EXP. — PART XVII. 1882.) K 21

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

The Tentacles are simple, they are stout and rather curled, about thirty in number
and all of much the same size.

Tlie Dorsal Tubercle is simply oval; the aperture is at the narrower anterior end; the
horns are not coiled, and nearly touch.

This is an ordinary and typical Styela, except that the apertures are not clearly
four lobed, but seem to have one or two extra projections each (PI. XIX. fig. 3). The
mantle and test are closely united; both are thin but strong, the test being in the
typical Cynthiad condition — namely, tough and leathery.

The branchial sac is normal. The eight folds are well marked, and the vessels and
meshes are of an ordinary size (PI. XIX. fig. 4). Two sizes of transverse vessels were
noticed, but they do not seem to alternate regularly. Besides these, a delicate
horizontal membrane appears to be invariably present, cutting each mesh into two areas
(PI. XIX. fig. 4, tr.').

One specimen of this species was obtained in the Antarctic Ocean, to the south of
Kerguelen Island, at Station 150; February 2, 1874; lat. 52° 4' S., long. 71° 22' E.;
depth, 150 fathoms; bottom temperature, l°-8 C. ; bottom, rock.

Styela lactea, Herdman (PI. XIX. figs. 7-8).

Styela lactea, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 68.

External Appearance. — The body is nearly rectangular, varying from an oblong to
a spherical shape ; it is erect and not compressed. The anterior end is straight and wide,
the posterior end is also straight and is nearly as wide. The dorsal and ventral edges are
slightly convex. The body is attached by the whole of the posterior end. The apertures
are both anterior ; they are nearly sessile, and are four-cleft. The branchial is at the
ventral edge of the anterior end, and is directed ventrally ; the atrial is at the dorsal edge
of the anterior end, and is directed anteriorly and dorsally.

The surface is smooth, but is seamed with transverse creases and slight folds, while
longitudinal ones are seen here and there. The colour is a creamy white.

Length of the body, 4"5 cm.; breadth of the body, 3'5 cm.

Tlie Test is thick, but soft and flexible ; it is quite opaque.

TJie Mantle is closely attached to the test. The musculature is fine, and is composed
of longitudinal and transverse bands intersecting at right angles.

The Branchial Sac has four folds upon each side. The internal longitudinal bars are
rather few, but wide ; there are about six on a fold, while they are few and distant in the
interspaces. The meshes are greatly elongated transversely, some of those near the
endostyle containing thirty or forty stigmata ; they are occasionally divided by narrow
horizontal membranes.

The Dorsal Lamina is a plain membrane, with no ribs, and an even margin.

REPORT ON THE TUNICATA. 157

Tlie Tentacles are filiform ; there are about thirty very long thin ones, with inter-
mediate shorter ones.

The Dorsal Tubercle is large, and is transversely elliptical in shape ; both horns are
rolled inwards, and form large spiral cods.

This is an attractive-looking species, with its nearly rectangular form and milk-white
soft looking test. From some points of view it looks like a little white barrel. The aper-
l ures are at the extremities of the anterior end, and are distinctly cross-slit (PI. XIX.
fig. 7).

The test is not at all like that of a typical Styela, it is thick, soft and flexible. The
mantle is muscular but thin, and is closely attached to the test.

The internal longitudinal bars are wide ribbon-like bands, but they are few and dis-
tantly placed. Consequently the meshes are greatly elongated transversely, containing
usually about fifteen stigmata each (PL XIX. fig. 8), but in some cases (e.g., the most
ventrally placed meshes) as many as forty. The transverse vessels are alternately
larger and smaller (tr. and tr.% while here and there the smaller ones fail, and a row of
very long stigmata is formed. Delicate horizontal membranes are present, here and there,
between the transverse vessels, dividing parts of the meshes, but they never extend far
(PL XIX. fig. 8).

Three specimens of this species were obtained at Kerguelen Island, at depths of from
10 to 100 fathoms.

Styela exigua, Herdman (PL XIX. figs. 5 and 6).

Styela exigua, Herdman, Pielira. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 68.

External Appearance. — The body is quadrangular in shape ; it is a little longer than
broad, and is somewhat compressed laterally. The anterior end is broad and rather flat,
while the posterior end is narrower and more rounded. The body is attached slightly
by the posterior end of the left side. The apertures are sessile and inconspicuous ;
the branchial is terminal and median, the atrial is on the dorsal edge, one-fourth of
the way down.

The surface is even, but partially covered by a thin coating of sand. The colour is a

dirty grey.

Length of the body, 1 cm.; breadth of the body, 0"8 cm.

Tlie Test is cartilaginous and thick, but soft.

Tlie Mantle is very thin, and is closely united to the test.

The Branchial Sac is wide, with four folds on cadi side. The alternate transverse
vessels are wider than the intermediate ones. The internal longitudinal bars are stout ;
there are six on each fold, and only one in the interspaces. The meshes are transversely
elongated, and contain each about six stigmata.

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

TJie Dorsal Lamina is narrow, and has the margin plain.

TJie Tentacles are simple and numerous ; they are of two sizes, placed long and
short alternately.

This is the smallest species of Styela in the collection, and there is nothing notable in
its external appearance (PL XIX. fig. 5). The test, which is comparatively thick, has a
little sand adhering to its outer surface, especially upon the left side.

There are four folds upon each side of the branchial sac. They do not project much,
but have each about six closely placed internal longitudinal bars (PI. XIX. fig. 6, br.f.),
while there is only one bar in each interspace between two folds. The two rows of meshes
lying between two folds are transversely elongated, and contain each about six stigmata ;
they are occasionally divided by delicate horizontal membranes (PI. XIX. fig. 6).

One specimen of Styela exigua was obtained at Port Jackson, Australia, in from 2 to
1 0 fathoms of water.

Styela clava, Herdman (PL XIX. figs. 9, 10).

Styela clava, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 70.

External Appearance. — This species is club-shaped, the pyriform body being supported
on a stalk of variable length ; it stands erect, and is not compressed. The anterior end is
narrow, but generally straight for a short distance ; from this the body widens rapidly for
the first two-fifths of its length, and then narrows more gradually in the remaining three-
fifths, the posterior end being prolonged into the stalk, which is generally about equal to
the body in length. The apertures are both at the anterior end ; they are four-cleft, and
more or less projecting, but minute and inconspicuous. The branchial is at the ventral
edge of the anterior end, and is directed ventrally ; the atrial is at the dorsal edge of the
anterior end, is more prominent than the branchial, and therefore more anterior, and is
directed anteriorly.

The surface is very irregular ; the posterior half of the body and the stalk are creased
longitudinally, and the anterior half of the body is nearly covered by irregularly shaped,
but smooth and blunt knobs, mostly directed anteriorly. The colour is a dirty white,
with occasionally a slight yellowish tinge.

Length (total), about 7 cm.; breadth (at broadest part of head), about 2 cm.

TJie Test is tough but thin, and almost papery, except in the knobs and processes.

TJie Mantle is very delicate, and is closely united to the test ; the musculature is very
feeble.

The Branchial Sac has four narrow folds upon each side. The internal longitudinal
bars are rather numerous, about nine on a fold and twelve in the interspaces. The meshes
are transversely elongated, contain each six stigmata, and are occasionally divided trans-
versely by a narrow membrane.

REPORT ON THE TUNICATA. 159

The Dorsal Lamina is a smooth and plain membrane, with no ribs and no teeth.

The Tentacles are about thirty in number, and arc rather closely placed; they are not
large and are all of about the same length, but some are rather stouter than others.

The Dorsal Tubercle is transversely elongated, and the horns are simply curled
inwards.

This appears to be rather a common species of Styela in Japanese seas. There are
about twenty specimens of it in the British Museum collection, which were brought home
from the Inland Sea, Japan, by Captain St. John, R.N., and there are also some specimens
from the same locality in the Liverpool Free Public Museum. The species, however,
appears never to have been described or figured.

The shape is very remarkable (PL XIX. fig. 9), as the posterior end is prolonged
to form a distinct stalk, while the anterior part has the surface of the otherwise thin,
papery test raised up into knobs or tubercles, giving the animal a rugged appearance, and
making it rather difficult to distinguish the apertures. These are both at the anterior
end, but the atrial is a little in front of the branchial.

The branchial sac has the folds narrow, but the internal longitudinal bars are numerous.
The transverse vessels are of two sizes, the larger is very wide and only occurs here and
there (PL XIX. fig. 10, tr.), the other size is much smaller and more numerous. The
meshes are nearly square, sometimes a little elongated antero-posteriorly, sometimes trans-
versely, and contain four to seven (usually five or six) stigmata each (PL XIX. fig. 10).

There are about thirty rather closely placed tentacles, which vary a little in size, but are
not arranged symmetrically. Several long, tubular, and shghtly ramified genital glands
are present upon each side of the body adhering to the inner surface of the mantle.

Several specimens of this species were dredged off Kobe\ Japan, at Station 233a ;
May 17 to 19, 1875 ; lat. 34° 35' N., long. 135° 10' E. ; depth, 8 fathoms and 50 fathoms ;
bottom, mud and sand.

Styela oblonga, Herdman (PL XX. figs. 7-9).

Styela oblonga, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 65.

External Appearance. — The body is oblong and erect ; it is broadest in the middle,
tapering slightly towards the anterior end, and more towards the posterior. The anterior
end is straight, the dorsal and ventral edges are shghtly convex, and the posterior end by
which the body is attached is narrow. The apertures are four-lobed, sessile, and placed
at the extremities of the anterior end.

The surface is finely wrinkled and roughened on rather more than the anterior half,
whilst it is smooth and slightly incrusted with sand on the posterior part. The colour is
a yellowish-brown, dull on the anterior half, and brighter posteriorly.

Length of the body, 3'5 cm.; breadth of the body, 2 cm.

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

The Ted is not thick, but is tough on the upper part ; it is thinner below, except at
the posterior end, where it is considerably thickened.

Tlw Mantle is thin and the musculature very delicate.

TJie Branchial Sac has four folds upon each side ; these scarcely project, and are
formed merely by a crowding together of the internal longitudinal bars, six to nine being
placed close together, and separated by wide spaces containing only three bars each. The
meshes are elongated antero-posteriorly, contain each only three stigmata, and are each
divided transversely by a narrow membrane.

The Dorsal Lamina is narrow and much crumpled, but is neither ribbed nor toothed.

Tlie Tentacles are simple and rather large, there are twelve of them.

The Dorsal Tubercle is rather prominent, it is cup-shaped, with a wide anterior opening.

This species was probably buried in sand nearly half its length. The posterior
part of the test is of a different texture from the anterior, has a different appearance
(PL XX. fig. 7), and is incrusted here and there with sand. The apertures are both
sessde, fourdobed, and distinctly visible at the anterior extremity. The test is thin,
leathery and tough, as in the typical Cynthiidse. At the posterior end, it is considerably
thickened.

The branchial sac has the folds in a rudimentary condition. They are no longer true
folds and do not project into the cavity of the sac, but are merely longitudinal tracts
along which there is a crowding together of the internal longitudinal bars (PL XX.
fig. 8. l>r.f.). Consequently, the meshes on the inner surface of this branchial sac are
of two sizes, — (1), the ordinary ones, which are nearly scpiare and contain each usually
three stigmata ; and (2), the very much narrower ones, half a dozen rows of which
represent the branchial fold. These last contain one or sometimes only part of a stigma.
The transverse vessels are of two sizes placed alternately. The narrow horizontal mem-
branes crossing the meshes are only present occasionally, and sometimes run for very
short distances only (PL XX. fig. 8).

In this sac there are a considerable number of muscidar fibres, which are present not
only in the large transverse vessels, but also in the fine longitudinal mterstigmatic
vessels (PL XX. fig. 9, m.f.). The dorsal lamina is much crumpled, but has a smooth
edge.

One specimen of this species was dredged in the South Atlantic (off the coast
of Buenos Ayres), at Station 320 ; February 14, 1876 ; lat. 37° 17' S., long. 53° 52' W.;
depth, 600 fathoms; bottom temperature, 2° 7 C; bottom, hard ground.

Styela flava, Herdman (PL XX. figs. 1-6).

Styela flava, Herdman, Prelim. Rep., Proe. Roy. Soe. Edin., 1880-81, p. 64.
External Appearance. — The body is rudely spherical, but is slightly elongated later-

REPORT ON THE TUNICATA. 161

ally; the anterior end is convex; the dorsal and ventral edges are free and rounded.
The body is attached by the posterior end and half of each side to a piece of coral. The
apertures are sessile, four-lobed, and moderately far apart ; they are placed at the opposite
ends of the anterior extremity.

The surface of the test is flat, but is minutely scaly ; these scales are largest and
most distinctly marked around the apertures. The colour is light yellow, with a brownish
tinge at the apertures, and is white on the area of attachment.

Length (antero-posterior), 1'6 cm.; breadth (from side to side), 2*4 cm.; thickness
(dorso-ventral), 2 cm.

The Test is thin, but very tough ; it is opaque, and is white and glistening on the
inner surface.

The Mantle is rather thin ; the muscular bands are numerous, but very fine.

The Branchial Sac has four folds upon each side. These are very slight, being merely
the approximation of a number of internal longitudinal bars. There are about ten bars
at these places, and ten in the intermediate opener parts. The meshes are square
or elongated antero-posteriorly, contain each four stigmata, and are divided each into
two areas by a narrow transverse membrane.

The Dorsal Lamina is ribbed transversely, and is slightly toothed at the edge.

Tlie Tentacles are simple and of three sizes; there are fifteen large, fifteen small, and
about thirty very minute ones, placed alternately.

Tlie Dorsal Tubercle is placed at the bottom (posterior extremity) of a rather deep
peritubercular area ; it is small and irregular in shape

This is in some respects rather an abnormal Styela. It is elongated laterally and
depressed, thus forming a wide convex anterior extremity (PI. XX. fig. 1), upon which
the small cross-slit branchial and atrial apertures are placed.

The surface of the test is modified into a series of small polygonal areas, winch give it
a scaly appearance. Each of the rounded or polygonal areas is marked by a series of
roughly concentric lines (PL XX. fig. 2), something like what Heller figures1 in the
case of Cynthia dura. The mantle is thin, but the muscle bands are \ • i y numerous.
They are delicate and are placed irregularly, running in all directions and forming a close
network (PI. XX. fig. 3).

The branchial sac has the folds in a rudimentary state, and formed merely by the
crowding together of the internal longitudinal bars along certain areas. In these
regions the meshes are of course very narrow (PI. XX. fig. 4, br.f.), while in the
intermediate spaces they are rather wide, and contain each four large stigmata. The
endostyle is conspicuous in this species ; it is wider than usual, and is of a reddish brown
colour.

1 Untersuchungeii li. J. Tun. des a<lriut. Meerea, Abth. 3, pi. iii. fig. 3.

1G2 THE VOYAGE OF H.M.S. CHALLENGER.

The dorsal lamina is in a condition rarely seen in the genus Styela. It is narrow,
and the free margin is cut into a series of wide triangular notches, leaving outstanding
teeth between them (PI. XX. fig. 5). The membrane is also ribbed transversely; a long rib
runs up the centre of each tooth to the apex, while between each pair of these there are
a number (about six) of shorter ribs which do not reach the margin. This lamina presents
a condition of affairs intermediate between the usual plain smooth-edged membrane of
the typical Styela, and the large distinct languets of Styela bythia.

The tentacles are of three sizes, placed so that if we call the largest A, and the
smallest C, they have the following arrangement : — A, C, B, C, A, &c. (PI. XX. fig.
6, tn., tn.' and hi."). The peritubercular area is very large, and is much deeper than the
dorsal tubercle, which is small and occupies merely the apex. Both horns are turned to
the right, the one outwards and the other inwards (PI. XX. fig. 6, d.t.).

The intestine is a narrow tube, and the loop which it forms is rather wide, — another
point in which this species differs from the typical members of the genus.

One specimen of Styela fiava was dredged in the South Atlantic, off the coast of
Buenos Ayres, at Station 320; February 14, 1876; lat. 37° 17' S., long. 53° 52' W.;
depth, 600 fathoms ; bottom temperature, 2°-7 C; bottom, hard ground.

Styela glans, Herdman (PL XX. figs. 10-13).

Styela glans, Herdman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1880-81, p. 65.

External Appearance. — The shape is regular, and is between conical and hemi-
spherical. The highest point of the body is at the ventral edge of the anterior end. The
posterior end is large and flat, and is attached to a piece of coral. The dorsal edge is
more convex than the ventral. The branchial aperture is anterior, and is placed at the
highest part, near the ventral edge ; the atrial is on the dorsal edge, two-thirds of the
way down ; both are sessile and inconspicuous.

The surface is roughish, but regular. The colour is a dark reddish-brown.

Length of the body, l-5 cm. ; breadth of the body, 1"2 cm.

The Test is not thick, but is tough ; it is white on the inner surface.

The Mantle is very thin and membranous.

The Branchial Sac has four slight folds upon each side, about five internal longi-
tudinal bars being crowded together, and the same number placed further apart alternately.
The meshes are elongated antero-posteriorly, and contain three stigmata each. They are
divided transversely by narrow membranes.

Tlie Dorsal Lamina is a narrow membrane.

The Tentacles are simple ; they are few and of moderate size.

Tlie Dorsal Tubercle is simple ; it is nearly circular in outline.

This is a small regularly shaped species, rather like an acorn in appearance (PL XX).

V

REPORT ON THE TUNICATA. 163

fig. 10). The apertures arc sessile and inconspicuous, and in their present contracted
condition appear to be scarcely lobed. The test is coriaceous and tough, coloured dark
reddish-brown upon the outside, and white internally.

The folds in the branchial sac are in the same rudimentary condition as in the two
preceding species. On the folds there are about five closely placed internal longitudinal
bars, and between these regions there are about the same number of bars placed further
apart. The meshes in the spaces between the folds are elongated antero-posteriorly,
and contain each three stigmata. The transverse vessels are of two very distinct sizes
(PI. XX. fig. 11, tr. and tr.') placed alternately, while a still smaller size (//•."), in the
form of a delicate bar, stretches across each row of meshes. Very delicate muscle-fibres
are visible in the transverse vessels, and also in the fine longitudinal interstigmatic
vessels (PI. XX. fig. 12, which shows also the mode of union of the delicate hori-
zontal bar (tr.") with the internal longitudinal bar, i.l.). Figure 13 on Plate XX.
represents the posterior end of the ventral edge of the sac, to show the lower extremity
of the endostyle (en.), and the ridge which is continued from it round the end of the
branchial sac to join the posterior extremity of the dorsal lamina. This figure also
shows how the internal longitudinal bars (i.l.) join the flat membrane at the lower end
of the branchial sac.

One specimen of Styela glans was dredged in the South Atlantic, off the coast of
Buenos Ayres, at Station 320; February 14, 1S7G ; lat. 37° 17' S., long. 53° 52' \Y.;
depth, 600 fathoms ; bottom temperature, 2°-7 C. ; bottom, hard ground.

Styela radicosa, n. sp. (PI. XXIV. figs. 6 and 7).

External Appearance. — The body is elongated, ovate or pyriform in shape ; it is not
compressed, and is attached by the posterior end. The anterior end is produced and
pointed, the posterior is broad and rounded, and is prolonged at the edges into several
long branched processes for attachment. The dorsal and ventral edges are nearly straight,
and converge towards the narrow anterior end ; the dorsal is more convex than the ventral.
The branchial aperture is terminal ; it is sessile but conspicuous, is indistinctly lobed,
and is directed anteriorly and ventrally ; the atrial is on the dorsal edge, one-third of
the way down ; it is sessile but conspicuous, and indistinctly lobed, and it is directed
dorsally.

The surface is even and nearly smooth, in some places it is finely wrinkled trans-
versely, and more rarely longitudinally; it is slightly corrugated around the branchial
and atrial apertures. The colour is made up of various shades of creamy white, buff, and
yellowish-brown, being lighter towards the posterior end and darker on the anterior end,
and especially around the branchial aperture.

Length (antero-posterior, not including the root-like processes), 4*5 cm.; breadth
(dorso-ventral), 2*8 cm. ; thickness (lateral, at posterior end), 2'2 cm.

(ZOOL. CHALL. EXF.— PART XVII. 1882.) J; 22

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

The Test is leathery ; it is tough and firm, but thin, and is slightly thickened at the
posterior end ; it is white on section, and glistening on the inner surface.

TJie Mantle is rather thick, and is strongly muscular. It is firmly attached to the
inner surface of the test in most places.

The Branchial Sac is large and moderately strong, and has four wide folds on each
side converging towards the oesophageal aperture. The transverse vessels are nearly all of
one size. Here and there, at distant intervals, a very much larger one is present. The
internal longitudinal bars are broad and ribbon-like ; there are six on each side of a fold,
and the same number in the interspace. The meshes are transversely elongated, and
contain each six or seven stigmata.

The Endostyle is prominent and conspicuous, and is rather undulating in its course.

TJie Dorsal Lamina is a plain broad membrane, with no ribs nor teeth. It extends
for about two-thirds of the length of the branchial sac.

TJie Tentacles are simple; they are numerous, of several sizes, but not placed regularly.

TJie Dorsal Tubercle is placed in a moderately large peritubercular area ; the shape is
cordate, elongated transversely, and with the horns simply turned in ; the aperture is
anterior.

The most noteworthy feature in the external appearance of this species is the pos-
teriorly placed root-like processes of the test, which are attached to fragments of shells
and Polyzoa (PL XXIV. fig. 6) ; the longest process measures 1*5 cm. The widest part
of the animal is just in front of the rounded posterior end, and the sides converge rapidly
towards the narrow anterior end, which terminates in the branchial aperture. The surface
is nearly smooth, the wrinkles being very fine and closely placed ; they are present chiefly
on the ventral edge of the right side. There are a number of radial corrugations round
the apertures, but no distinct lobes.

The thin, tough yellowish test exactly resembles that of Microcosmus. The mantle
is of a yellowish-brown colour, and has the musculature strongly developed. It is chiefly
circular.

The folds in the branchial sac are large, and are supported by wide internal longi-
tudinal bars (PL XXIV. fig. 7). The occasional wide transverse vessel (tr.) equals in
size the height of a mesh. The stigmata have about the same breadth as the fine longi-
tudinal vessels and are very regular. The meshes are also very uniform and are never
divided transversely.

The endostyle is prominent and conspicuous, and is rather undulating in its course
along the ventral edge.

The oesophageal aperture is placed about two-thirds of the way down the dorsal edge
of the branchial sac.

REPORT ON THE TUNICATA. 165

One specimen of this species was obtained at Station 1G2, April 2, 1874, off Eas1
Moncceur Island, Bass Strait ; depth, 38 to 40 fathoms ; bottom, sandy.

Bathyoncus, n. gen.

Body ovate, sessile, slightly attached ; apertures inconspicuous.

Test membranous and transparent.

Branchial Sac with several slight folds on each side, and a larger one on the left

side near the dorsal edge ; meshes square, no stigmata.
Dorsal Lamina a plain membrane.
Tentacles simple.

Alimentary Canal on the left side.
Genitalia a single elongated gland on each side.

This genus is formed for the reception of a single small specimen, found in deep
water in the Southern Ocean. The chief peculiarity is in the structure of the branchial
sac. Further remarks will be found under the description of the species.

Bathyoncus mirabilis, n. sp. (PI. XXIV. figs. 8-12).

External Appearance. — The body is between ovate and discoidal in shape, and is
compressed laterally. The anterior end is wide, slightly convex, and almost flat. The
posterior end is narrower, and is slightly produced to form an area of attachment. The
dorsal and ventral edges are equally but slightly convex, and converge towards the
narrow posterior end. The sides are flattened. The apertures are both anterior, and
are distant, inconspicuous and sessile ; the branchial is near the anterior end of the
ventral edge, and is directed ventrally and slightly anteriorly ; the atrial is at the dorsal
edge of the wide anterior end, and is directed anteriorly and dorsally.

The surface is even and smooth, except towards the posterior end, where it is a little
irregular and rough from adhering sand, &c. The colour is pale yellowish-grey.
Length of the body, 1"4 cm. ; breadth of the body, 1*2 cm.
TJie Test is thin, membranous, and rather transparent.

TJie Mantle is thin, and the musculature is not strong. The muscle bands are
numerous and closely placed but very fine.

The Branchial Sac is very simple, forming a wide-meshed but strong network. There
is one prominent fold on the left side, near the dorsal edge ; and there arc several others,
much slighter, on each side. Each of these slighter folds is merely formed of three
internal longitudinal liars, placed closely and united by short transverse ducts, which
are twice as numerous as the transverse vessels, being placed both opposite to and
between them. The transverse vessels are wide but distant, while the internal longi-

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

tudinal bars arc very strong. The meshes intermediate to the slighter folds are large
and square, and are not subdivided by any smaller vessels.

The Dorsal Lamina is a broad plain membrane, slightly undulating at the free edge.

The Tentacles are large and simple, from twenty to twenty-five in number, and all of
one size

The Dorsal Tubercle is small and simple, nearly circular in outline, and has the aperture
anterior and rather wide. The horns are not coiled.

The Alimentary Canal is situated on the left side, near the dorsal edge.

The Genitalia are two elongated glands — one on each side.

This remarkable form is closely allied to Styela, from which it is separated generically
on account of the peculiar branchial sac, which exhibits the simple structure only known
in the two allied genera Culeolus and Fungulus.

In external appearance (PI. XXIV. fig. 8) it is small and rudely ovate, with the pos-
terior end narrow and roughened. On account of the thin and transparent test it looks
rather like a Molgnla. The mantle has a large number of muscle bands, forming a minute
network, but they are very delicate. The branchial sac (PL XXIV. fig. 9) is, however,
undoubtedly the most remarkable feature. It is formed of two series of vessels — the
transverse and the internal longitudinal — intersecting at right angles. The internal
longitudinal bars are placed in threes, and each set (forming one of the slighter folds or
projections) is held together by a double series of short transverse vessels, smaller inter-
mediate ones being placed between those which extend all round the sac. In other words, the
smaller alternate transverse vessels are confined to the folds. The meshes between the folds
(PI. XXIV. fig. 9) are large and square. As no fine longitudinal vessels are present, there
are no true stigmata. On the left side of the branchial sac, near the dorsal lamina, there is
a collection of about six or eight internal longitudinal bars, forming a much larger fold.

The tentacles (PL XXIV fig. 10) are simple and stout. They are not long, are all of
one size, and are pretty closely placed. The anterior face of each is a flattened plain
surface while the posterior or branchial is highly arched and somewhat irregular, the
membrane being loose and puffed out in parts as in most Molgulidee.

The dorsal tubercle (PL XXIV. fig. 11) is rather simple, and is placed at the anterior
extremity of the funnel-shaped tube leading to the neural gland. The peritubercular area
is not large, and has an irregularly triangular form. The nerve ganglion is large and
oblong in shape. It gives off a considerable number of nerves at each extremity. Its
anterior (branchial) end is just at the posterior angle of the peritubercular area.

The intestine is of much the same cabbre throughout its length. It is rather small,
and lies near the dorsal edge of the left side.

The genital glands are in the form of elongated undulating bodies attached to the
inner surface of the mantle, one on each side, and converging towards the atrial aperture.

RETORT ON THE TUNICATA. 107

The genital duct is formed of two tidies lying side by side — the oviduct and the
vas deferens. They open close together, not far from the atrial aperture, ami close to the
outer of two circlets of minute tentacular processes, which projecl from the inner surface
ot the cloacal wall close to the atrial aperture (PI. XXIV, tig. 12). These processes seem
like a pair of rudimentary diaphragms in the atrial siphon.

One specimen of this species was obtained in the Southern Ocean, between the Cape
of Good Hope and Kerguelen Island, at Station 147; December 30, 1873 ; lat. 40° 16' S.,
long. 48°27'E. ; depth, 1G00 fathoms; bottom temperature, 0°'8 C. ; bottom, globigeriiia
ooze.

Pol yea rpa, Heller.

Cynthia, Savigny, Mthnoires sur les Animaux sans Vert&bres. Pt. ii. fasc. 1. 1S16. In part.

Ascidia, Quoy and Gaimard, Voyage de I'Astrolabe — Zool., t. iii. 1830-34. In part.

Cynthia, Forbes and Hartley, British Mollusca, vol. i. 1848-53. In part.

Styela, Hancock, Anat. and Physiol, of Tunieata, Jouin. Linn. Sue. 18G8. In pail.

Cynthia, Kupffer, Jahresber. der Commias., &c 1875. In part.

Polycarpa, Heller, Untersuch. ii. d. Tunicaten d. adriat. Meeres., Abth. 3. 1877.

Polycarpa, Heller, Beitrage zur niihern Kenntniss der Tunicaten. 1878.

Styela, Traustedt, Oversigt over de fra Danmark, &c, Ascidise Simplices. 18S0. In pail.

Body attached, sessile, rarely stalked, occasionally incrusted with sand. Bran-
chial and atrial apertures either four-lobed or cross-slit.

Test usually coriaceous, rarely cartilaginous.

Branchial Sac with four or less than four folds upon each side.

Tentacles always simple.

Intestine forming a wide loop.

Genitalia in the form of a large number of small masses scattered over the inner
side of the mantle.

Heller separated Polycarpa from Styela in 1877, giving as the chief distinguishing
features the wide loop formed by the intestine, ami the presence of a large number of
small genital glands, to which he gave the name of " polycarps." The close relationship
of Polycarpa to Styela has been already discussed (see under Styela, p. 149).

In external appearance and the nature of the test this genus varies greatly. The typical
condition is attached and sessile, with a thin but tough and leathery test, not incrusted with
sand. A short stalk is however occasionally formed, as in Polycarpa viridis, by a pr< '^liga-
tion of the posterior end of the body, and the test may become thickened and cartilaginous
in consistency, as in Polycarpa sulcata. In some species inerusting sand is present in
quantities ranging from a few adhering grains, as in Polycarpa radieata, to a complete
coatino-, as mPolycarpa tinctor. While finally in Polycarpa molguloides the investment
is very thick, and the grains are attached to long delicate hairs as in a typical species of
the genus Molgula.

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

The mantle also varies considerably in its strength and degree of muscularity. In
Polycarpa sulcata the mantle is strong, and (in the spirit specimens) has contracted com-
pletely away from the test, while in Polycarpa quadrata and others, it is thin and
closely adherent to the inner surface of the test. The branchial sac agrees in all its
characters very closely with that of Styela. The tentacles are invariably simple, but may
differ greatly in size. The dorsal lamina may be slightly crenated at the edge, but is not
known to be transversely ribbed or distinctly toothed.

The intestine usually curves round in rather an open loop, but this varies somewhat,
and cannot be depended upon as a characteristic.

The reproductive system, however, is peculiar : there are a large number of distinct
genital masses or polycarps present, scattered over the inner surface of the mantle, and
projecting into the peribranchial space. Besides these there are usually a number of
other distinct bodies, rounded, oval, oblong, or sometimes stalked, which at first sight
appear very similar to the genital glands, but are in reality merely processes of the con-
nective tissue of the mantle, which contain numerous blood sinuses, and have been called
" endocarps." These may serve as pads to protect the genital masses lying between
them, or may be reservoirs into which the blood circulating in the mantle passes when
the body is violently contracted, as suggested by Kupffer.

There are twelve species of Polycarpa in the Challenger collection, and eleven of these
were new to science, the only known species which was obtained being Polycarpa tinctor,
Quoy and Gaimard.

Polycarpa viridis, Herdman (PI. XXI. figs. 7-14).

Polycarpa viridis, Herdman, Prelim. Eep., Proc. Eoy. Soe. Edin., 1880-81, p. 74.

External Appearance. — The body is variable in shape, but usually more or less
pyriform, the anterior end being the broadest, and the posterior forming a short stalk, some-
times more elongated, and twisted, by the lower end of which the animal is attached. Both
apertures are placed at the anterior end, generally a little to the right side of the extremity.
The branchial is terminal or subterminal ; the atrial is a little way down the dorsal edge,
and not distant from the branchial; both are four-lobed, sessile, and inconspicuous.

The surface is not uneven, but is generally more or less covered by other animals,
sand, shell fragments, &c, adhering to it. The colour is a dull green, and is darkest in
the neighbourhood of the apertures.

Length of the body, 3 cm.; breadth of the body, 2-5 cm.

The Test is not thick but is tough; it is rough externally from adhering sand, &c,
and is of a beautiful dark green colour throughout. Vessels are very numerous, and are
seen anastomosing frequently.

TIte Mantle is muscular, is closely united to the test, and is of a dull green colour.

REPORT ON THE TUNICATA. 1G9

The Branchial Sac has four folds upon each Bide. There are three small transverse,
vessels between each pair of large ones. About eight internal longitudinal baxs are
usually present on the folds, and four in the interspace. The meshes are transversely
elongated and contain each nine to twelve stigmata.

The Dorsal Lamina is narrow ; it is nut ribbed, and the margin is plain.

The Tentacles are simple, filiform, and crowded ; there are about seventy, placed long
and short alternately.

The Dorsal Tubercle is small and rudely circular in outline; the left horn is coiled
inwards, and the right outwards.

This is a curious species; the shape is rather variable, as may be seen from the two
specimens figured (PL XXI. figs. 7 and 8). The dimensions given above are those of a
fairly large individual ; some of the specimens are much smaller. The body is more or less
globular, and the stalk is always very short. The apertures are slightly prominent and
very distinctly four-cleft (PL XXI. fig. 8), the branchial is nearly terminal and towards
the ventral edge, the atrial is on the antero-dorsal edge, about a quarter of the way
round it from the branchial aperture to the posterior end. Sand, mud and fragments of
shell adhere to the stalk and the posterior part of the body, and in some cases cover most
of the surface. Where not thus concealed by foreign bodies, the surface has a rich dark
green colour, the neighbourhood of the apertures being always the darkest part.

The dark green test is closely united to the underlying mantle, which is also green.
Blood-vessels are very numerous on the test, and may be seen ramifying and anastomosing
freely (PL XXI. fig. 9, v.). Minute ovate or fusiform cells of a yellowish colour are very
numerous, scattered through the test matrix ; while in its inner part, below most of
the vessels, bundles of delicate fibres may be seen here and there, running in different
directions (PL XXI. fig. 9, /.); these do not belong to the mantle. The large dark-
coloured and mostly angular bodies, seen in fig. 9, are minute sand grains imbedded in the
test matrix. The epithelium (ectoderm) on the inner surface of the test is distinct.

The branchial sac has four distinct folds upon each side, each fold having about eight
closely placed internal longitudinal bars (PL XXI. fig. 10, br.f.). In the interspaces
the bars are rather distantly placed, and consequently the meshes are large and contain
each usually ten or eleven stigmata. The arrangement of the transverse vessels — three
smaller ones alternating with two sizes of large ones — is very well marked and constant,
and all of them have undulating or jagged edges, which appear to be due to irregular
membranous expansions at their sides (I'l. XXI. tig. 10. tr., tr.' and tr.").

Muscular fibres are present in all the vessels, and are arranged with great regularity.
The larger transverse vessels have two bands of fibres running along them, while the smaller
vessels have a single band each. Longitudinal bands are also present. Theselie intheinter-
stigmatic vessels, and each band forks as it crosses one of the larger transverse vessels,

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

o-ivino- oft* a branch for each side of the nearest stigma. These branches unite soon with
the corresponding divisions of the two adjacent bands to form the original number of
longitudinally running bundles, one for each interstigmatic vessel (PI. XXI. fig. 11).

The tentacles are numerous and are closely placed (PI. XXI. fig. 12) ; they differ
greatly in size. The dorsal tubercle is large and rather prominent (PI. XXI. fig. 12, d.t.);
both horns are coiled in the same direction, to the right.

The polycarps are numerous on the inner surface of the mantle, and vary from one to
three millimeters in length. Each is hermaphrodite, and has the ovary occupying the centre
and the rounded base (PI. XXI. fig. 13), while the elongated spermatic vesicles are arranged
around the periphery, so as to enclose and partially conceal the ova. These vesicles are
fusiform or pyriforrn (PI. XXI. fig. 14, t.v.), and their ducts join to form two canals,
one on each side, which finally unite into the single vas deferens (v.cl.), which runs along-
side the short and wide oviduct (PI. XXI. fig. 13, o.d.), and opens with it on the terminal
papilla of the polycarp.

This species was found by the Challenger expedition at Port Jackson, Australia, where
several specimens were obtained, at depths ranging from 2 to 15 fathoms, as follows : —
17th April 1874, 2 to 10 fathoms, 1 specimen ; 20th April 1874, 6 fathoms, 5 specimens ;
23rd April 1874, 6 to 15 fathoms, 4 specimens.

Polycarpa tinctor, Quoy and Gaimard (sp.) (PI. XXI. figs. 1-6).

Ascidia tinctor, Quoy and Gaimard, Voyage de l'Astrolabe — Zoologie, torn. iii. p. 608, pi. xci.
figs. 1 and 2.

I have identified this species, found in considerable quantity by the Challenger
expedition at Port Jackson, with the Ascidia tinctor of Quoy and Gaimard, entirely from
the external appearance, as depicted in the atlas of the voyage of the Astrolabe.

The characteristic appearance of the Challenger specimens is shown well on PI. XXL,
where figure 1 shows a large specimen from the left side, the projection at the right side
of the upper (anterior) end containing the atrial siphon. Figure 2 represents another
specimen from the right side, while figure 3 is from the front, and shows the two con-
spicuous, distinctly four-lobed apertures. The atrial is always more prominent than the
branchial, and is placed nearly one-third of the way down.

The test is thin and membranous, and is in all cases entirely covered with a close
coating of fine sand.

The mantle is very muscular, and is only attached to the test here and there. The
muscle fibres form continuous outer circular and inner longitudinal coats over the whole
1 >ody. The sphincters around the siphons are very strong, and there is a partial diaphragm
at the base of the atrial siphon, fringed with twenty short pointed lobes.

The branchial sac (PL XXI. fig. 4) has four well-marked folds upon each side (hi:/.),
and each of them has about eight internal longitudinal liars, while there are about the

REPORT ON THE TUNICATA. 171

same number more distantly placed in the interspaces. The transverse vessels are all
much about the same size, and most of them have wide horizontal membranes hanging
from their inner edges (PL XXI. figs. 4 and 5, tr. and A.m.). The meshes are square
or a little elongated transversely, are often divided by delicate horizontal membranes
(PI. XXI. fig. 5, h.m.), and contain four or five stigmata each. The endostyle is well
marked and may be seen distinctly running to the base of the long sac.

The tentacles are simple and are not long. They are of three sizes, placed usually
with several of the smaller ones between each pair of larger ones (PI. XXI. fig.
6, tn.).

The dorsal tubercle (PL XXI. fig. 6, d.t.) is large and prominent, and each horn forms
a spiral ; the right one is large and is turned inwards, while the left is much smaller and
coils outwards. The peritubercular area is shallow and symmetrical. Both polycarps
and endocarps are very numerous.

About a dozen specimens of Polycarpa tinctor were obtained at Port Jackson, at
depths varying from 2 to 15 fathoms.

Polycarpa minuta, Herdman (PL XXII. figs. 1-4).

Polycarpa minuta, Herdman, Prelim. Eep., Proc. Roy. Soe. Eilin., 1880-81, p. 78.

External Appearance. — This species is dome-shaped, or nearly hemispherical ; the
anterior end is convex, and the posterior is wide, flattened, attached, and slightly expanded
at the margin. The apertures are both anterior ; they are not distant, and are sessile but
distinct.

The surface is perfectly smooth and even. The colour is pale-yellowish brown.

Length of the body, 0'6 cm.; breadth of the body, 0'9 cm.

The Test is thin, but tough and strong.

The Mantle adheres closely to the test, and is very thin.

The Branchial Sac has four folds upon each side. The transverse vessels are all of
the same size. The internal longitudinal bars are very few, there being only two between
each pair of folds. The meshes are transversely elongated, and contain each six to eight
stigmata.

The Dorsal Lamina is a plain membrane.

The Tentacles are numerous and filiform.

This is a very small species of Poh/carpa, and is rather like Styela grossularia, van
Peneden, in general appearance. It forms a small blister-like prominence on the stone to
which it adheres (PL XXII. fig. 1), is perfectly smooth on the surface, and of a yellowish-
brown colour. The apertures are placed close together at the anterior end. The test and
the mantle are both very thin, and adhere together closelv.

The branchial sac (PL XXIL fig. 2) has the folds in the rudimentary condition which

(ZUOL. CUAI.L. EXF. — FART XVII. — 1882.) J; '_'.'>

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

has been already seen in several species of Styela (e.g., Styela oblonga and Sty ela flaw*).
Tiny are represented in this sac by four closely placed internal longitudinal bars (PI.
XXII. tig. 2, br.f.), forming meshes which contain each one stigma only.

The transverse vessels are all of one size, and are rather wide. The internal longitudinal
bars are broad and ribbon-like, and bound rather wide series of meshes, of which there are
three rows in each interspace. Each mesh contains six or seven stigmata, and occasionally
narrow transverse bars are present, crossing them for short distances. The tentacles are
numerous and very delicate. Each of the polycarps on the inner surface of the mantle
is somewhat flask-shaped (PI. XXII. fig. 3, g.), and has a funnel-like duct at the
narrower end. The walls of this genital mass contain scattered rod-shaped calcareous
spicula (PI. XXII. fig. 4, sp.), rather like those found in the test of Cynthia complanata.

One specimen of Polycarpa minuta was dredged in the Antarctic Ocean (to the south
of Kerguelen Island), at Station 150 ; February 2, 1874 ; lat. 52° 4' S., long. 71° 22' E.;
depth, 150 fathoms; bottom temperature, 1°"8 C. ; bottom, rock.

Polycarpa molguloides, Herdman (PL XXII. figs. 5-7).

Polycarpa molguloides, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 76.

External Appearance. — The body is transversely ovate, or sub-cylindrical ; it is
elongated dorso-ventrally and depressed ; and is attached by the wide posterior end. The
apertures are distant, they are both on the anterior end (upper surface), and are incon-
spicuous.

The surface is entirely covered by a thick layer of sand, shells, &c. The colour is dark
brown.

Length (antero-posterior), 3 cm.; breadth (dorso-ventral), 7 cm.; thickness (lateral),
4 cm.

Tlie Test is moderately thick and leathery ; it is covered with branched hair-like
processes, to which the sand-grains, &c, are attached.

The Mantle adheres closely to the test ; it is thick and rough, and the musculature
is feeble.

Tlie Branchial Sac has four folds upon each side. The transverse vessels are nearly all
of one size, but occasionally a larger one is met with. There are six internal longitudinal
bars on the folds, and four in the interspaces. The meshes are transversely elongated, and
contain each twelve stigmata.

Tl>e Dorsal Lamina is a plain membrane.

The Tentacles are numerous and crowded ; they are all of one length, and are of a dark
brown colour.

This is a very remarkable species, and is exactly like a Molgula in external appearance
(PI. XXII. fig. 5), the body being entirely covered with a thick coating of sand and

i; Knurr on the tunicata 173

shell fragments. The shape also is peculiar. It is much elongated dorso-ventrally, and

is depressed so as to form a transversely elongated sausage-shaped body.

The test also is like that of most species of Molgula, in being prolonged into branched
hair-like processes, to which the sand is attached. The branchial sac is strong, on account
of the presence of numerous very wide internal longitudinal liars (PI. XXII. figs. 6
and 7, i.h). Most of the transverse vessels are very narrow, but occasionally one meets
with one which is considerably wider. The meshes in the interspaces are transversely
elongated, and contain each about a dozen rather narrow stigmata. The whole branchial
sac, and the numerous tentacles, are of a dark brown colour.

The polycarps only project slightly, as they are imbedded in the thick mantle.

Two specimens of this curious species were dredged off East Moncceur Island in Bass
Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sand.

Pohjcarpa quadrata, Herdman (PI. XXII. figs. 8-10).

Polycarpa quadrata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 78.

External Appearance. — The body is oblong or oval in shape, erect and somewhat
compressed laterally ; both ends are broad and rounded, and the dorsal and ventral edges
are nearly straight and parallel. The body is attached chiefly by the posterior end. The
branchial aperture is terminal, sessile, inconspicuous and minute, the atrial is on the
dorsal edge, more than one-third of the way from the anterior to the posterior end, it
also is minute and inconspicuous.

The surface is considerably creased in all directions, especially round the apertures.
The colour is dirty white.

Length of the body, 2 cm.; breadth of the body, 1"6 cm.

The Test is not thick, it is tough and strong, but not stiff, and is white and glistening
on the inner surface.

The Mantle is very thin, and adheres closely to the test.

The Branchial Sac has four slight folds upon each side, and in these places the in-
ternal longitudinal bars are very numerous and close. The meshes are elongated antero-
posteriorly, and are usually divided by a narrow transverse membrane, and each contains
from one to four stigmata.

The Dorsal Lamina is a plain membrane.

TJie Tentacles are simple.

The Dorsal Tubercle is ovate in outline ; it is very minute, and is placed at the
posterior end of a deep peritubercular area.

This species has the typical Cynthiad appearance (PL XXI 1. fig. 8). The test is thick
but tough, is not covered with sand, and is of a dirty white colour. The apertures are
minute, and are both cross-slit (see atrial aperture in PI. XXII. fig. 8).

17 I THE VOYAGE OF H.M.S. CHALLENGER.

The folds in the branchial sac are formed merely by the approximation of interna]
longitudinal bars, which are very numerous, but not wide (PI. XXII. figs. 9 and 10, i.L).
The transverse vessels are of two sizes, and three of the smaller size occur between two
larger ones. The meshes are elongated antero -posteriorly, and are usually divided by a
narrow horizontal membrane attached to each fine interstigmatic vessel where they
intersect (PL XXII. fig. 10, km.).

The dorsal tubercle, which is ovate in outline and very small, is situated at the foot of
the deep peritubercular area. The intestine forms a wide loop. The polycarps are few,
only three or four apparently upon each side of the body. The endocarps, however, are
very numerous.

In some respects this species shows affinities with certain species of Styela (e.g., Styela
glans, Styela oblonga, and Styela flava), but it is quite distinct from them all; and
although the polycarps are few, the intestinal curve is like that of a Polycarpa.

Three specimens of this species were discovered adhering to the clumps of spicules
projecting from the sides of a large Hexactinellid sponge. They differ somewhat in
external form, probably on account of their mode of attachment.

The locality is off Ki Island, in the Malay Archipelago, at Station 192 ; September 26,
1874 ; kit, 5° 42' S., long. 132° 25' E. ; depth, 129 fathoms; bottom, mud.

Polycarpa pilella, Herdman (PL XXII. figs. 11-15).

Polycarpa pilella, Herdman, Prelim. Eep., Proe. Eoy. Soc. Edin., 1880-81, p. 73.

External Appearance. — The body is a little variable in shape, but is generally
spherical or ellipsoidal, occasionally rather pyriforrn, the posterior end being the narrower
of the two ; it is not compressed, and is erect ; the anterior end is wide and convex, and
the body is attached by the posterior end. The apertures are both at the anterior end ;
they are moderately far apart, and are not conspicuous.

The surface is entirely covered by a layer of sand. The colour is yellowish-brown.

Length of the body, 6 mm. ; breadth of the body, 4 mm.

T/ie Test is thin, but strong.

The Mantle is rather strong. The muscular fibres are delicate, but very numerous,
formino- a close network.

The Branchial Sac has four folds upon each side. The transverse vessels are all equal
in size. There are about eight internal longitudinal bars on the folds, and the same
number in the interspaces. The meshes are elongated antero-posteriorly, and contain each
three stigmata.

Tlie Dorsal Lamina is a plain membrane with an irregular edge.

Hie Tentacles are filiform ; there are about twenty large ones, with one or two
smaller between each pair of larger ones.

Tlie Dorsal Tubercle appears to be very variable in shape.

REPORT ON THE TUNICATA. 175

This is the smallest species of Simple Ascidian in the collection, and is probably the
smallest species known, with the exception of species of the genus Perophora. The
surface is entirely covered with a fine coating of sand, so that the body looks simply like
a little rounded pellet of sand (PI. XXII. fig. 11).

The branchial sac is delicate (PI. XXII. fig. 12), and the internal longitudinal bars are
especially slender, but they are numerous. The usual meshes are elongated antero-
posteriorly, and contain each three stigmata, but at the right side of the dorsal lamina there
is a much wider series of meshes, which contain each about nine stigmata (PL XXII.
fig. 12). Many of the rows of meshes are divided transversely by delicate membranes.

The dorsal lamina is not ribbed, but the edge is irregular and slightly toothed here
and there (PI. XXII. fig. 12, d.l.). The simple filiform tentacles are of about four sizes.
There are about twenty of the two largest sizes placed alternately, and between every two
of these are two, three or four of the two smaller sizes placed irregularly (PI. XXII.
fig. 13, tn. and '».').

The dorsal tubercle appears very variable. In one specimen examined it was irregu-
larly horse-shoe shaped, with both horns rolled inwards ; while in another specimen it
was much simpler, being merely an antero-posteriorly elongated aperture, with two slight
lateral diverticula (PI. XXII. figs. 13 and 14, d.t.). It is very large, extending across
the prasbranchial zone to the tentacles, the edges of the aperture being bounded by
columnar ciliated epithelium (fig. 14, d.t.'). There is a large rounded neural mass placed
just behind the apex of the peritubercular area, and formed chiefly of the subneural gland
(PL XXII. fig. 13, gl.n.). The prsebranchial zone is rather broad and is semi-trans-
parent, showing the circular and longitudinal muscle bundles of the mantle very distinctly
(PL XXII. fig. 13,2.).

The course of the alimentary canal is shown in figure 15, Plate XXII. The oesophagus
is short and curved, and opens into a globular stomach (at.), from which the intestine
curves ventrally and then anteriorly (/.). It does not then turn back posteriorly, but slants
across dorsally and anteriorly, to reach the neighbourhood of the atrial aperture. The
anus, which is not distant from the oesophageal aperture, has an undulating edge (PL
XXII. fig. 15, a.).

About a dozen specimens of this small species were obtained at Bahia, Brazil, in from
7 to 20 fathoms.

Polycarpa rigida, Herdman (PL XX I II. figs. 1-2).

Polycarpa rigida, Herdman, Prelim. Rep., Proc. Roy. Soc. Eilin., 1880-81, p. 76.

External Appearance. — The body is ohlong and erect, with the anterior end pointed
and the dorsal and ventral edges nearly straight and parallel. The posterior end is nearly
straight, and is moderately wide, forming the point of attachment. The branchial aperture

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

is terminal and projecting, while the atrial is on the dorsal edge, fully one-third of the
way from the anterior to the posterior end, and projecting. Both are very indistinctly
lobed.

The surface is even but roughish, and partly covered by foreign bodies. The colour
is a dull greyish-brown, but dull yellow round the apertures.

Length of the body, 8 cm. ; breadth of the body, 3 cm.

TJie Test is not very thick and not tough, but is very stiff, like cardboard. It is white
on section and on the inner surface.

The Mantle is thin, and adheres closely to the test; the musculature is feeble.

The Branchial Sac has four folds upon each side. The transverse vessels are of two
sizes, about twelve narrow ones being placed between every two larger ones. There are
about twelve internal longitudinal bars on the folds, and six in the interspaces. The
meshes are transversely elongated, and contain twelve stigmata each.

TJie Dorsal Lamina is a narrow plain membrane, with the edge even.

The Tentacles are simple and closely placed ; they are stout, and about forty in
number, all of one length.

The Dorsal Tubercle is oblong, lies in a very large triangular peritubercular area, and
is directed forwards and to the left.

This is a very large species to belong to the genus Pohjcarpa. It stands erect,
attached by the posterior end, and having the branchial aperture uppermost (PL XXIII.
fig. 1). The test, though not thick, is very stiff, and has a few shell fragments and other
foreign matter adhering.

The branchial sac is strong, and has very wide internal longitudinal bars (PI. XXIII.
fig. 2, i.l.). These are numerous, and form well developed folds. In the interspaces the
meshes are transversely elongated. The. larger size of transverse vessel is very wide, as
wide as one of the rows of stigmata. This sac is somewhat irregular in parts, and in two
places in the portion figured (PI. XXIII. fig. 2) the passage of one row of stigmata into
two rows is seen. In the middle of the lower edge of the figure some of the stigmata are
reduced to very small oval or rounded apertures. The tentacles are large, are all of one
length, and are crowded together.

The intestine forms a very wide loop. The polycarps are deeply imbedded in the
mantle, and hence only project slightly. In the genital masses some of the mature ova,
which were incidentally examined, had each several distinct germinal spots.

Two specimens of Polycarpa rigida were obtained off East Moncceur Island, in
Bass Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sand.

REPORT ON THE TUNICATA. 177

Polycarpa longisiphonica, Herdman (PL XXIII. figs. 3-G).

Polycarpa longisiphonica, Herdman, Prelim. Rep., J'roc. Roy. Soc. EJin., 1880-81, p. 77.

External Appearance. — The body is oblong, or somewhat flask-shaped, and erect.
The posterior end is large and rounded, the anterior end narrow and pointed. It is
apparently not attached, or only slightly by the posterior third of the left side. The
apertures are conspicuous, at the ends of very long siphons; the branchial is terminal,
and is directed anteriorly ; the atrial is on the dorsal edge, half way down, and is directed
dorsally and anteriorly ; it is fully as long as the branchial siphon.

The surface is covered, except on the siphons, by a fine coating of sand and shell
fragments. The colour is a dark brown.

Length of the body, 7 cm. ; breadth of the body, 4 cm.

The Test is thin and brittle, but rather stiff.

The Mantle is thin, and adheres closely to the test. The musculature is feeble.

The Branchial Sac has four folds upon each side. Every fifth or sixth transverse vessel
is wider than the intermediate ones, which are all of one size. There are eight internal
longitudinal bars on the folds, and about the same number in the interspaces. The
meshes are square, they contain each four to six stigmata, and are occasionally divided by
a narrow horizontal membrane.

TJie Dorsal Lamina is a narrow and plain-edged membrane.

The Tentacles are not very long, and are placed rather far apart. There are about
eighteen, some shorter than others, but not placed symmetrically.

The Dorsal Tubercle is circular iu outline, or somewhat horse-shoe- shaped, with both
ends turned slightly outwards.

This species resembles Polycarpa rigida in its erect body and stiff test, partly covered
with adhering foreign matter (PI. XXIII. fig. 3). If attached at all, it is only slightly
so by the posterior part of the left side. The length of the siphons upon which the aper-
tures are placed is a characteristic feature.

As in the last species, the transverse vessels are of two sizes (PI. XXIII. fig. 4, tr. and
tr.'), but here the internal longitudinal bars are narrow, and not wide as in Polycarpa
rigida. The interspaces are wide, and have each about eight rows of meshes. The
internal longitudinal bars are crowded on the folds. In one of the specimens of this
species all the vessels in the sac appear to be rather wider. The ordinary meshes in
the interspaces are square, or a little elongated transversely, and are occasionally divided
by narrow horizontal membranes.

The tentacles are of different sizes, but these are not arranged symmetrically. In one
specimen examined there were about sixteen larger tentacles and two or three very small
ones between each pair of larger. There is a double line of columnar cells (probably
ciliated when Hving) running down the anterior face of each tentacle, and becoming

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

continuous at the apex (PL XXIII. figs. 5 and 6). The polycarps are numerous and
large, and of a yellow colour.

Three specimens of this species were found at Port Jackson, Australia, in from 6 to 15
fathoms.

Polycarpa irregularis, Herdman (PL XXIII. figs. 7 and 8).

Polycarpa irregularis, Herdman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1880-81, p. 72.

External Appearance. — The body is irregularly oblong, somewhat pyriform, erect,
and rather compressed laterally. The anterior and posterior ends are narrow, and the
middle two-fourths are wide, and have the dorsal and ventral edges parallel ; the ventral
edge is straight throughout ; the dorsal slopes in its anterior and posterior fourths, but is
straight in its central two-fourths. The body is attached by the narrow but irregular
posterior end. The branchial aperture is terminal and prominent, and is surrounded by
four large lobes and four small ones ; the atrial is on the dorsal edge, rather more than
one quarter of the way down ; it is distinct.

The surface is very irregular ; it is cut up by deep grooves and folds, and is partially
covered by foreign bodies. The colour is a dirty yellowish-white.

Length of the body, 6 cm. ; breadth of the body, 3"5 cm.

The Test is rather thick and tough ; it is white and glistening on the inner surface.

The Mantle is thin, and the musculature is not strong.

The Branchial Sac has four folds upon each side. There are two or three narrow
transverse vessels between each pair of wider ones. About eight internal longitudinal
bars are present on the folds, and twelve in the interspaces. The meshes are transversely
elongated, and contain each six stigmata.

The Dorsal Lamina is narrow and smooth.

The Tentacles are linear and rather distant ; they are twenty-four in number, and are
coloured black ; some are rather smaller than the others, but are not placed alternately.

The Dorsal Tubercle is ovate in shape, but has the narrow end placed posteriorly ; it
is much convoluted and marked with black.

The surface of this large Polycarpa is curiously irregular (PL XXIII. fig. 7), especially
at the posterior end. The test is thick and tough, and of a yellowish-white colour. The
apertures are both distinct. The branchial has eight lobes, but four of them are large,
while the others are merely intermediate smaller processes or folds.

In the branchial sac there are two distinct sizes of transverse vessels. Each pair of
larger ones is separated by either three or, more rarely, two smaller ones (PL XXIII.
fig. 8). The stigmata are small, and show a considerable amount of irregularity.
Horizontal membranes are not much developed.

REPORT ON THE TUNICATA. 179

The intestine forms a wide loop. The yellow endocaxps are numerous, but rather
small.

One specimen of this species was dredged at the Philippine Islands, at Station 208 ;
January 17, 1875 ; hit. 11° 37' N., long. 123° 32' E. ; depth, 18 fathoms ; bottom, mud.

Polycarpa sulcata, Herdman (PI. XXIII. figs. 9-13).

Polycarpa sulcata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 73.

External Appearance. — The body is between ovate and pyramidal in shape, and is not
compressed. The anterior end is narrow, but rounded; the posterior end is broad and
rounded; the ventral edge is very convex, while the dorsal is convex posteriorly and
concave anteriorly. The body is attached by the posterior end of the ventral edge. The
branchial aperture is not terminal, but is twisted round to the dorsal edge; it is pro-
minent, and is directed dorsally. The atrial is on the dorsal edge, about half-way from
the anterior to the posterior end, and directed dorsally. Both are four-lobed, wide and
conspicuous.

The surface is smooth but uneven ; it is cut up by deep creases and folds into
rounded pad-like projections. The colour is a dull creamy-white.

Length of the body, 5-5 cm. ; breadth of the body, 3-5 cm.

The Test is thick and tough, but soft and not stiff. The inner surface is white, with
small dark dots over it.

The Mantle is thin, does not adhere to the test, and is of a dark brown colour; the
musculature is not strong.

Tlie Branchial Sac has four narrow folds upon each side. Three narrow transverse
vessels are usually present between each pair of wider ones. The internal longitudinal
bars are few. The meshes are transversely elongated, and contain each about eight to
twelve stigmata.

The Dorsal Lamina is smooth, and very narrow.

The Tentacles consist of twelve rather large, but not very long, distantly placed ones,
with two or three very minute ones between each pair of the former.

The Dorsal Tubercle is large and irregular, with a spongy appearance.

This species has a very peculiar external appearance (IT. XXIII. figs. 9 and 10). The
anterior end appears to have been bent over, so that the branchial aperture comes to be
directed dorsally. Both apertures are wide and square. The test is thick and tough, but
lather soft, and is raised up on its external surface into a number of large rounded knobs
and ridges. In minute structure the test is composed of a finely and closely fibrillated
matrix, having somewhat the appearance of close felt (PI. XXIII. fig. 13, t.m.), and in
this are scattered here and there large hollow spaces or vessels containing Mood cor-
puscles. These form the small dark dots which are seen with the naked eye scattered

(ZOOL. CHALL. EXP. PART XVII, — 1882.) K 24

180 THE* VOYAGE OF H.M.S. CHALLENGER.

over the inner white surface of the test, and they are merely cavities in connection
with the Mood- vessels, which may also be seen here and there in sections. A number
of smaller blood cavities are present just below the outer surface of the test, recalling the
arrangement in Ouleolus, but the larger vesicles are always more deeply placed
(PL XXIII. fig. 13).

The folds in the branchial sac are narrow, and the internal longitudinal liars are
slender. The. arrangement of the transverse vessels is shown on figure 11, Plate
XXIII. ; above the large transverse vessel (tr.) two rows of stigmata are seen passing
into one. In some parts of the sac the stigmata are longer and narrower than in the
part figured. On account of the fewness of the internal longitudinal bars, the meshes
are much elongated transversely. Muscle fibres are seen well in some of the vessels
of this branchial sac (PI. XXIII. fig. 12).

Three specimens of Pohjcarpa sulcata were dredged off Banda, in the Moluccas ;
depth, 17 fathoms.

Pohjcarpa pedata, Herdman (PL XXIV. figs. 1 and 2).

Pohjcarpa pedata, Hordman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 71.

External Appearance. — This species is irregularly club-shaped, and consists of a
long stalk supporting a somewhat globular body produced anteriorly. The posterior end
of the body is broad and rounded, and passes rapidly into the narrow stalk, which is
nearly as long as the body. The ventral edge is nearly straight ; the dorsal is strongly
convex in its posterior half, and straight in the anterior part, The animal is attached 1 iy
the extremity of the long narrow stalk. The branchial aperture is terminal, it is very
prominent, and is directed anteriorly ; the atrial is on the dorsal edge, about half way
down the body; it projects, and is directed anteriorly and dorsally; both are distinctly
four-cleft.

The surface is smooth, but grooved and creased somewhat. The colour is yellowish-
white, with a tinge of red on the stalk.

Length of the body (total), 10"5 cm.; breadth of the body, 4 cm.

The Test is thin but tough.

The Mantle is moderately thick, but adheres here and there to the test ; the musculature
is close but not strong.

TJw Branchial Sac has four folds upon each side. The transverse vessels are all of one
size. The internal longitudinal bars are numerous. The meshes are slightly elongated
transversely, and contain each five or six stigmata,

TJie Dorsal Lamina is a plain membrane.

The Tentacles are long and of a la-own colour. There are twenty -five of them, and
they are all of one length.

KKPOUT ON THE TUNICATA. 181

This is a very remarkably shaped animal (PL XXIV. fig. 1). The body is some-
wbat globular, with an anterior process containing the branchial siphon, and is supported
upon a stalk, which, however, is dearly a mere process of the posterior end. This .stalk
is about as long as the body, and is curved round ventrally. The apertures are both
prominent and distinctly four-cleft (PL XXIV. fig. 1). The surface is considerably
grooved and ridged, but otherwise smooth ; it has a yellowish -white colour.

The branchial sac presents a curious appearance in the single specimen known, from
the circumstance that all the vessels are engorged with blood corpuscles, thus forming a
natural injection. Most of the transverse vessels are of the same size (PL XXIV. fig. 2),
but occasionally a larger one is met with. The meshes are slightly elongate.! transversely,
and are rarely divided by a horizontal membrane.

The margin of the anus is cleft into a series of processes. The atrial siphon has at its
base a diaphragm, which has its free edge finely fringed. The polycarps are large ; tenta-
cular endocarps are also present.

One specimen of Pol year pa pedata was dredged near the Philippine Islands, at
Station 212 ; January 30, 1875 ; lat. 0° 55' N., long. 122° 15' E.; depth, 10 to 20
fathoms ; bottom, sand.

Polycarpa radicata, Herdman (PL XXIV. figs. 3-5).

Pohjcur-pa radicata, Herdmau, Prelim. Eep., Proc. Roy. Soc. Edin., 1880-81, p. 75.

External Appearance. — This species is club-shaped and erect, consisting of a globular
body, supported on a narrow stalk equalling the body in length. The anterior end is
rather broader than the posterior, which is continuous with the stalk ; the edges an'
convex. The stalk is long and narrow, anil spreads out somewhat at the lower end,
where it is attached. The apertures are both at the anterior end, they are sessile and
inconspicuous, with the lobes indistinct. The branchial is on the ventral edge of the
anterior end, while the atrial is about the centre, and is slightly the more anterior of the two.

The surface is even, but slightly sandy. The colour is a dull greyish-yellow.

Length (total), 3-5 cm.; breadth of the body, 17 cm. ; length of the body, 2 cm.

The Test is moderately thick and strong, but not still'.

The Mantle is closely united to the test, and is thin.

The Branchial Sac has four folds upon each side. There are three narrow transverse
vessels between each pair of wide ones. The internal longitudinal liars an' ribbon-like, tiny-
are close and numerous on the fold, but few in the interspaces. The meshes are trans-
versely elongated, and contain each six to twelve stigmata.

The Dorsal Lamina is narrow.

Tlie Tentacles are simple and numerous; there are about fifty, crowded together;
they are of different sizes, but do not alternate.

[s2 THE VOYAGE OF H.M.S. CHALLENGER.

The Dorsal Tubercle is circular or slightly elongated transversely, one end is turned
out and one turned in.

This is a curiously shaped little species, and like Polycarpa pedata has the posterior
end of the body prolonged to form a peduncle (PI. XXIV. figs. 3 and 4). The lower end
of the peduncle gives off a number of fine prolongations or rootlets, by means of which
the animal is attached.

The test is rather thick and strong, is not irregular on the surface, but has sand grains
attached here and there. The folds in the branchial sac are well marked, and have the
internal longitudinal bars closely placed, while in the interspaces they are few and distant
(PL XXIV. fig. 5); consequently the meshes are wide, and contain mostly ten or twelve
stigmata. The transverse vessels are of two sizes, arranged so that three smaller and one
larger alternate. The tentacles are numerous and closely crowded. There are numerous
yellow polycarps present.

In external appearance this species is not unlike Polycarpa pedunculata, Heller,1 but
is much smaller, and differs in several details of internal structure, such as the number of
tentacles.

Two specimens of this species were collected, both in Australia. One is from Port
Jackson, depth, 6 fathoms ; the other was trawled off Twofold Bay, south-east coast of
Australia, at Station 163; April 4, 1874; depth, 120 fathoms.

Farudy Ascidiid.e.

Body fixed ; usually sessile, rarely stalked.

Test cartilaginous or gelatinous, rarely chitinous. Branchial aperture usually

eight-lobed ; atrial aperture usually sixdobed.
Branchial Sac not folded ; internal longitudinal bars present, and usually papil-

lated ; stigmata straight or curved.
Tentacles simple, filiform.
Intestine either placed at one side of the branchial sac, or extending beyond it

posteriorly.
Genitalia always in close connection with the alimentary canal.

This is a very compact family, its only close allies being the Clavelinidse, from which
it is sharply defined by its want of the property of budding. From the other two fanidies,
the Molgulidae and the Cynthiidae, it is distinguished by its branchial sac not being-
disposed in folds. The remaining characteristics given above, though none of them alone
would sufficiently define the family, are all of importance, and when taken collec-
tively separate the Ascidiidae from other Simple Ascidians.

1 Beitrage zur nahern KennUiiss der Tunicaten, p. 24.

REPORT ON THE TUNICATA. \<\

The body is always fixed, usually by the posterior end and more or less of the left
side ; it is in almost all cases sessile, and when not so the stalk is merely a narrow pro-
longation of the posterior end, and is not comparable with the peduncle of the Bolteninse.
The test is usually cartilaginous or gelatinous, and is found in all stages between these
two conditions. In the genus Chelyosoma, an aberrant form, it is developed into horny
plates. The number of lobes surrounding the apertures may vary considerably. In the
majority of cases it is — branchial eight-lobed, atrial six-lobed, bu1 the branchial is frequently
found with seven or with nine lobes, while in Chelyosoma it is only six-lobed ; in Abyss-
ascidia, on the other hand, the branchial aperture is surrounded by fourteen lobes, and
the atrial aperture by nine. The musculature of the mantle is generally very irregular,
but in the genus dona a series of conspicuous longitudinally running bands are formed.

The branchial sac is never folded, but in many species of Ascidia it is thrown into
a series of minute longitudinal plications, which will be described in detail further on.
These must not be confused with the conspicuous folds so characteristic of the Cynthiidse
and the Molgulidse, which are entirely wanting in the present family. The internal
longitudinal bars, which are almost invariably present, are in the form of more or less
stout, rounded bars, in contrast to the ribbon-like vessels found in many of the Cynthiidse
and some of the Molgulidse. Usually in the Ascidiidse the bars bear on then- inner sides
papillae, varying in size, shape, number and arrangement according to the genus and
species. The stigmata are straight and approximately parallel, except in the genera
Corella, Corynascidia and Chelyosoma, where they are curved and arranged spirally
round certain central points. The tentacles are invariably simple, elongated, tapering
filaments, like those of the Styelinse, but usually rather thinner.

The arrangement of the viscera varies considerably. In most forms, including the
genus Ascidia, the stomach and intestine lie upon the left side of the branchial sac ; but
in the nearly allied Ciona, they extend considerably beyond the branchial sac posteriorly,
so as to form a rudimentary abdomen. In Corella and Abyssascidia, again, the stomach,
intestine, and heart are placed upon the right side of the branchial sac, and the course of
the intestine is different from that found iu Ascidia.

The genital glands are always found in close relation with the alimentary canal, gener-
ally applied to the wall of the posterior part of the stomach, or the first part of the intes-
tine, and often occupying the intestinal loop; they are never found attached to the mantle
independently of, and at a distance from, the intestine, as is so frequently the case in the
Cynthiidse and the Molgulidse.

The genus Ascidia is, even in its modern restricted sense, the typical and most impor-
tant genus of this family. It contains by far the largest number of species, and is a
central point round which the other genera may be arranged, according to their affinities.
The first oi these is Pachychlama ; this form and Ascidia are more closely allied than
any other two of the genera. At the one extreme end of the series of which As.

1-1

THE VOYAGE OF H.M.S. CHALLENGER.

and Pachychlcena occupy the centre, may be placed dona, leading towards the Clave
1 in iil;c. while two genera, Corella and Corynascidia, occupy the opposite end. Abyss-
ascidia comes in between Ascidia and Corella, while the two somewhat aberrant forms,
Rhodosoma and Chelyosoma, must be considered as allied, the former to Ascidia and
Ciona, and the latter to Ascidia and Corella, but both having marked peculiarities of
their own, which prevent their being placed in the direct line between their allies. The
remaining form, Hypobythius, is in some respects (e.g., the structure of the branchial sac)
the most abnormal of all. It is allied to Ciona, and has also affinities with Ascidia or
Pachychlcena, but cannot be placed in a direct line between them. These relationships
may be shown in a schematic form thus : —

Rhodosoma

Ciona

Ascidia

Pachychlcena

Chelyosoma

■Abyssascidia

Corella

Corynascidia

Hypobythivs

This scheme might be divided by two vertical lines, so as to separate three groups, — -
a central, containing Ascidia and Pachychlcena, and two lateral, the one containing
Corella, Corynascidia, Chelyosoma, and Abyssascidia ; and the other the three remaining
genera, Ciona and the two abnormal forms Rhodosoma and Hypobythius.

The table immediately following shows how these nine genera may be distinguished
by a few of their more important characters. It seems impossible, however, to arrange
them satisfactorily in sub-families. For example, the first division in this table, founded
on the condition of the dorsal lamina, throws Ciona in contact with Corella, and
separates it from the much more nearly allied Hypobyth his. In other respects, however,
this table is not an unnatural arrangement ; it brings Abyssascidia, Corynascidia, and
Corella into the same section, and puts Pachychlcena and Ascidia into close contact.

I: K PORT ON THE TUNICATA.

!*.->

Ascidiid.e.

Dorsal lamina present
as a membrane.

Dorsal lamina present in the
form of laiiKuets.

Branchial sac divided
into regular
meshes.

Branchial sac an
irregular
network.

Illjpollljtlliils.

Test soft and

more or less

flexible.

Ascidia.

Test hard,

very thick

and stiff.

Pachyehlaena.

Stigmata
straight.

Stigmata
curved.

Test un-
modified.

Intestine on

left side of,

and posterior

to, branchial

sac.

Ciona.

Intestine on
right side of
branchial sac.

Abyssascidia.

Test having
the anterior
part modified
so as to form

a covering
over the bran-
chial and

atrial
apertures.

Rhtidoximia.

Test modified
into horny
plates.

Chelyosoma.

Test more or
less soft and
gelatinous.

Body
pedunculated.

( 'orynascidia.

Body

sessile.

( ;>,f lla.

The family may be broken up, as seen below, into three groups according to the
structure of the branchial sac, but this is not altogether satisfactory, since it involves
the separation of Abyssascidia from its near allies Corolla and Covynascidi<< ; otherwise
it seems the most natural arrangement possible

AsCIDIIDiE.

Branchial sac with no internal longitudinal bars.

Hypobytuinx.

I
Hypobythiu .

I nternal longitudinal bars pri

Stigmata Btraij lit.

I

ASI ll'I.V.E.

I

Ciona.

Ascidia.

Pachyehlaena.

Rhodo8oma.

Abyssascidia.

Stigmata curved.

I
CoRi'i.r.ix.K.

I

i !

Corn
Chelyosoma.

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

The Challenger collection contains representatives of all these genera, with the
exception of Rhodosoma and Chelyosoma. Four of the remaining seven, namely,
HypobytMus, Pachychlcena, Abyssasddia and Corynascidia have been founded for the
reception of new forms obtained during the expedition.

Corynascidia, n. gen.

External Appearance. — Shape elongated, pyriform, pedunculated ; apertures not

lobed.
Test gelatinous or membranous.
Branchial Sac extremely delicate. Internal longitudinal bars present, but not

provided with papillae. Interstigmatic vessels coiled spirally.
Dorsal Lamina in the form of languets.
Tentacles simple, filiform.
Viscera on dorsal edge of branchial sac, running antero-posteriorly.

This curious genus is closely allied to Corella, but is so different from it in many
particulars as to necessitate the formation of a new genus. Its greatest peculiarities are
the pyriform pedunculated body, the delicate spirally coiled vessels in the branchial sac,
and the form and position of the viscera, Further remarks on its structure and affinities
will be given at the end of the description of the single species known.

Corynascidia suhmi, n. sp. (PI. XXV.).

External Appearance. — The shape is pyriform, and consists of a body which is flat-
tened laterally, and a long stalk. The body is elongated, and the anterior and dorsal
ends are short, while the ventral and posterior are greatly elongated, so as to produce a
triangular shape. The stalk is about as long as the bod)-, and is very thin where it joins
the bod)' at the ventral edge of the posterior end. It gradually iucreases in width as it
runs backwards, till at the point of attachment it is three times its original breadth. The
apertures are not lobed ; they are rather wide, and slightly projecting ; the branchial is
at the ventral edge of the anterior end, and is directed anteriorly and ventrally ; the atrial
is at the dorsal edge, and is directed dorsally. There is a deep depression in the middle
of the dorsal edge, just opposite the stalk.

The surface is smooth and pretty even. Some parts of the body are finely creased
longitudinally. The surface of the stalk is smooth and glistening. The colour is dirty
grey, with a yellowish tinge on parts of the body.

Length of the body (dorso-ventral), 7 cm.; breadth of the body (antero -posterior), 3'2
cm.; length of the stalk, 7 '5 cm.

REPORT ON THE TUNICATA. 187

The Test is between membranous and gelatinous in consistency ; it is thin and semi-
transparent.

The Mantle is very thin, and the musculature is slight. It extends for a short
distance into the upper end of the long peduncle.

The Branchial Sac is extremely delicate and filmy ; all the vessels are very narrow.
The transverse vessels are all of about the same size, and are connected by longitudinal
ducts, so as to form square meshes, in which the secondary or interstigmatic vessels are
coiled spirally, as in Corella ; each spiral has about three turns. Internal longitudinal
bars are present, but are not papillated ; they are borne on long triangular connecting
ducts.

T/ie Dorsal Lamina is represented by long triangular languets.

The Tentacles are filiform, and are very long and thin ; they are numerous, arranged
rather closely, and are of two sizes, placed alternately larger and smaller.

Tlie Dorsal Tubercle is irregularly oval in outbne. The aperture is anterior and
narrow, and the horns almost meet.

Tlie Viscera are relatively of small size, compact, and form a narrow band running
antero-posteriorly along the dorsal edge of the branchial sac.

This remarkable form seems to be a deep-sea representative of Corella, and is also
allied to Ascidia and Paclujchlcena through Abyssascidia. It is, however, quite distinct
from any of these genera.

The dimensions given above are those of the specimen from Station 299. Of the two
others, from Station 146, the perfect specimen is smaller, whde the injured one was
apparently much larger. Their dimensions are as follows : —

A. B.

Length of the hody, about 5 cm. about 8 cm.

Greatest breadth of the body, about 2 -5 cm. about 5 cm.

Breadth of the body at posterior end, 0"8 cm.

Length of the stalk, 5 cm. stalk absent.

The shape is remarkable. It is the only known stalked form among the Ascicliidas,
and is much more like an abnormal Molgulid. The body is pear-shaped, the ventral
and posterior sides being pulled out so as to form a long tapering process, which becomes
continuous with the stalk (PL XXV. fig. 1). The apertures are situated at the two
extremities of the anterior end, and are wide and tubular, but devoid of lobes.

The stalk is smooth and glistening, it is rather tougher looking than the rest of the
test, and widens as it recedes from the body to its point of attachment to a manganese
nodule (PI. XXV. fig. 1). The upper narrow part of the stalk is twisted in one of the
specimens.

The mantle is thin and membranous, with only a few distant muscle bands radiating

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) R 25

|SS THE VOYAGE OF H.M.S. CHALLENGER.

through it. The muscle bands end abruptly by dividing each into two or three conical
processes, which suddenly taper off in the manner so characteristic of the muscle bands in
the genus Corella, and also., as will be seen below, of those in the mantle of Abyssascidta
wyvillii.

The branchial sac is the most striking form known in the Ascidiidse, arid has a very
remarkable shape, its ventral, and especially its posterior, edges being greatly prolonged,
so that its posterior end comes to be much the widest part (PI. XXV. fig. 2). It is
wonderfully delicate and somewhat like a spider's web. The regularly arranged trans-
verse vessels are united by very narrow longitudinal tubes (PI. XXV. fig. 6, w.l.), so as
to form large squares in which the spirals are placed. All the vessels are very thin, with
wide spaces between them, and the spirals are converted into either squares or polygons
by the presence of four or more straight vessels radiating outwards from the centre of each
of the spirals to the four corners, and sometimes to the sides of the circumscribed square
(PI. XXV. fig. 6, r.v. and r.'v.)

The internal longitudinal bars are very delicate, and are borne on the apices of long
triangular membranous flaps or connecting ducts, which arise from the transverse vessels,
but are connected by no horizontal membranes. These flaps arise at the corners of the
squares (PI. XXV. fig. 6, c.d.), and in the middles of their upper and lower sides ;
consequently an internal longitudinal bar runs across the middle of each square contain-
ing a spiral, and there are twice as many true meshes as there are of these squares. The
true meshes (formed by the transverse vessels and the internal longitudinal bars) are
elongated antero-posteriorly.

In the first specimen examined, the languets along the dorsal edge of the branchial
sac were all of one size, triangular in shape, not long, and placed in a double row
(PL XXV. fig. 7). In one of the other individuals, however, they were found to be much
narrower and more elongated, of two distinct sizes, occurring alternately, and placed in a
single row (PI. XXV. fig. 8). The difference is considerable, but scarcely sufficient to
warrant the establishment of a distinct species.

The numerous tentacles (PI. XXV. fig. 5, tn. and in! ) are very long and thin. The
longer ones are as a rule about twice the length of the shorter ones. The endostyle. is
inconspicuous, and runs from the neighbourhood of the branchial aperture apparently only
as far as the narrow end of the sac near the point of attachment of the peduncle
(PL XXV. fig. 2, en.).

The alimentary and reproductive viscera are in many respects like those in the genera
Corella and Abyssascidia. As in the latter genus, they are very small compared with
the size of the body and of the branchial sac. They form a compact elongated mass,
lying along the dorsal edge of the sac, and a little on its right side (PL XXV. fig. 2).
The oesophagus opens at the dorsal edge, about one-half of the way down the branchial
sac, and runs posteriorly for a short distance, and then opens into the narrower

REPORT ON THE TUNICATA. 1 Ml

anterior end of the pyriform and moderately rapacious stomach (PL XXV. figs. 2 and 3, st.).
The intestine emerges from the more globular posterior end of the stomach, and stdl
runs posteriorly for a short distance, and then, having reached the posterior end of the
mantle, turns abruptly on itself from the right to the left side (PI. XXV. fig. 3, i.), and runs
anteriorly in close contact with the stomach and oesophagus. It then with a slightly undulat-
ing course continues as the rectum (PI. XXV. figs. 2 and 3, r.) up to the atrial aperture.

The genitalia (PL XXV. figs. 2 and 3, g.) form a single lobed mass covering the
posterior half of the stomach and the commencement of the intestine, but not extending
into the loop. The ducts course along the dorsal side of the intestine, and terminate
like the anus just inside the atrial aperture (PL XXV. figs. 2 and 3, g.d.).

One specimen of this species was obtained between Juan Fernandez and Valparaiso,
at Station 299; December 14, 1875; kit. 33° 31' S.. long. 74° 43' W.; depth, 2160
fathoms; bottom temperature, 1°"1 C; grey mud ; and two specimens, one considerably
injured, were obtained between the Cape of Good Hope and Kerguelen Island, at Station
146; December 29, 1873 ; kit. 46° 46' S., long. 45° 31' E.; depth, 1375 fathoms; bottom
temperature, 1°'5 C; bottom, globigerina ooze.

Corella, Alder and Hancock.

Ascidia, 0. F. Miiller, Zoologia Danica, vol. ii. 1780. In part.

Ascidia, Forbes and Hanley, British Mollusca, vol. i. 1853. In part.

Ascidia, Alder, Observations on British Tunicata, Ann. and Mag. Nat. Hist., ser. iii. vol. ii.

1863. In part.
Corella, Hancock, On the larval state of Molgula, &c, Ann. aud Mag. Nat. Hist., ser. iv. voL

vi. p. 362. 1870.
Corella, Kuptfer, Jahresber. der Commiss. 1875.

Corella, Traustedt, Oversigt over de fra Danmark, &c, Ascidias Simplices. 1880.
Corella, Traustedt, Vestindiske Ascidiae Simplices. 1881.

Body attached, sessile. Branchial aperture eightdobed, atrial sixdobed.

Test cartdaginous, but soft and semi-transparent.

Branchial Sac not.longitudinally plicated. Internal longitudinal bars present,

but not papillated ; stigmata curved; fine longitudinal vessels coiled

spirally.
Dorsal Lamina represented by languets.
Tentacles simple.

Viscera placed upon the right side of the branchial sac.
Genitalia situated on the intestinal Loop.

The species forming the genus Corel!", although now universally admitted to be very
distinct from those of Ascidia, were included in the latter genus until within the lasl
twelve to fifteen years.

In 1863 Alder pointed out the more important characteristics o£ Ascidia parallelo-

TOO

THE VOYAGE OF H.M.S. CHALLENGER.

gramma, 0. F. Miiller, and suggested that it should be separated from the other species
of Ascidia as a new genus ; but this was not formally done until Hancock, in 1870, pub-
lished a paper in the Annals and Magazine of Natural History, containing descriptions of
a laro-e number of new species of British Tunicata, two of which, Corella larvceformis
and Corella ovata, he referred to the newly-made genus. He defined the genus chiefly
by the peculiarities which Alder had pointed out seven years before as distinguishing
Corella parallelogramma, namely, the position and course of the alimentary canal, the
position of the heart upon the right side of the branchial sac, and the spiral interstig-
matic vessels.

The Challenger expedition added a third species (Corella japonica), from the Japanese
Seas, and quite recently (1881), Traustedt has described two new species (Corella minuta
and Corella eumyota) from the West Indies.

These different species may be distinguished according to the following table : —

Corella.

Atrial aperture anterior.

Atrial aperture dorsal.

Placed upon a very
long projection.

I
0. larvceformis.

Sessile.

Musculature strong
on left side.

I
C. parallelogramma.

Musculature very weak
on both sides.

I

C. minuta.

Anterior end of body wide.

Atrial aperture not far from

branchial.

I
C. ovata.

Anterior end of body narrow.

Atrial aperture distant from

branchial.

Tentacles of two
sizes.

I
C. eumyota.

Tentacles all of
one size.

I
C. japonica.

Corella japonica, Herdman (PI. XXVI.).

Corella japonica, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80., p. 472.

External Appearance. — The shape is ovate or longish ovate, the anterior end being
narrower than the posterior, which is rounded ; the ventral edge is rather more convex
than the dorsal. The body is somewhat compressed laterally, and is attached by the
posterior end and the posterior half of the lower or right side. The base is occasionally
produced into short tufts for attachment. The branchial aperture is terminal or sub-
terminal, being slightly on the left side of the anterior extremity. The atrial is about

REPORT ON THE TTJNICATA. 191

one-third of the way from the anterior to the posterior end, and on the left side, not
far from the dorsal edge. Both apertures are sessile and inconspicuous.

The surface is slightly rough, especially at the anterior end ; it is generally prolonged
here and there at the edges and the lower surface into fine hair dike branched processes.
The colour is dull grey.

Length of the body, 3 cm.; breadth of the body, 1 cm.

Tlie Test is thin, but moderately strong ; no vessels are visible

The Mantle is very delicate over most of the right side and half of the left, while on
the anterior and dorsal edge of the right side, and the anterior half of the left side
muscular bands are extraordinarily developed, and attain a great thickness (up to 0'3, and
in one or two cases 0'5, mm.). The siphons are muscular and fairly prominent. The
branchial aperture is provided with eight, and the atrial with six ring-shaped ocelli, of a
light rust colour.

Tlie Branchial Sac is not plicated. The transverse vessels are large and are all equal
in size. They are joined by short wide longitudinal vessels, thus forming square meshes
in which the spirally coiled secondary or interstigmatic vessels lie. Internal longitudinal
bars are numerous, being in excess of the wide longitudinal vessels. They are delicate
but distinct, and are united to the transverse vessels by wide horizontal membranes,
which are present in the proportion of two or three to every transverse vessel. The
stigmata are curved, and are placed spirally, in rows of square meshes separated by the
transverse vessels. The stigmata near the outside of the mesh are usually crescentic,
whde those further in are longer and are coiled spirally.

Tlie Dorsal Lamina is represented by a series of long tapering languets.

The Tentacles are very numerous, touching at their bases ; they are all of one size,
and are moderately long and filiform.

The Dorsal Tubercle is regular, the outline is between cordate and ovate, and both
horns are coiled inwards.

The Alimentary Canal is moderately large, and is placed on the right side of the
branchial sac. The stomach is nearly globular. The intestine is wide, and curves round
ventrally and posteriorly to the stomach.

The Genitalia are on the first part of the intestine, and in the intestinal loop.

This species, which agrees in all generic characters with Coretta as defined by Hancock
in 1870, is the only species collected during the Challenger expedition which can be
referred to that genus.

The general form of the body distinguishes this species clearly from Corella parallelo-
gramma, 0. F. Midler ; Corella minuta, Traustedt ; Corelhi larvceformis, Hancock; and
Corella ovata, Hancock. It is more nearly allied to Corella eumyota, Traustedt, but may,
I think, be distinguished from that species also by several details of structure. In Corella

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

japonica the atrial aperture is situated on the dorsal edge, only about one-third of the dis-
tance from the anterior to the posterior end, while in Corella eumyota it appears from
Traustedt's figures to be about half-way down. In Corella japonica the musculature is
very strongly developed along the dorsal part of the left side (PI. XXVI. fig. 2, m.b.),
while in Corella eumyota there is no such disproportionate development. The two species
differ again in the structure of the branchial sac, as Traustedt's figures show a more
irregular arrangement of the sjiirals than that found in Corella japonica.

The delicate branched processes of the test (PL XXVI. fig. 1 ) suggest the very similar
structures so well known in the Molgulidae, and in this case also sand grains are frequently
found adhering to or entangled in them, though never in any quantity.

The very remarkable muscle bands seen in the mantle, especially on the left side just
below the siphons (PI. XXVI. fig. 2, m.b.), have a considerable resemblance to those found
in Abyssascidia wyvillii, and are even thicker than in that species. In some places they
terminate very abruptly (PL XXVI. fig. 6), their wide ends breaking up into a number
of short thick pointed processes, which rapidly taper off to a fine extremity. The ocelli
round the apertures are distinct. They are of a rust-red colour, and appear ring-shaped,
possibly from the presence of a light yellowish spot in the centre of the red.

The branchial sac has the structure usually found in Corella ; the transverse vessels
and the longitudinal tubes connecting them are wide, while the internal longitudinal bars
are very narrow, and are more numerous than the rows of spirals (PL XXVI. figs. 4 and 5).
The horizontal membranes are wide, and are very numerous. They have frequently
curved prolongations or connecting ducts which join the internal longitudinal bars in
certain positions. These look as if they projected from the bars, and thus they gave rise
to the erroneous statement in the description of this species in the Preliminary Report,
that the internal longitudinal bars are provided with long curved papillae. One other
point in regard to the branchial sac must be noticed. In some places the internal
longitudinal bars are very much broken up, as seen in figure 8. A bar may end csecally
close to its point of attachment to a horizontal membrane, and may begin again at the
next membrane, leaving a gap between the two ; it may then continue normally, or it
may terminate again, in which case there will be a short piece of generally curled tube
ending csecally in both directions, and attached by the middle to a horizontal membrane
(PL XXVI. fig. 8). This irregularity in the internal longitudinal bars may also be
observed in Corella parallelogramma of our own coasts.

The languets along the dorsal edge of the sac are narrow and tapering ; they are all
of the same size, and are not placed closely (PL XXVI. fig. 7, /.). The tentacles are
very closely packed, and are apparently all of the same size. The symmetrically-shaped
dorsal tubercle (PL XXVI. fig. 9, d.t.) lies in a shallow triangular peritubercular area,
and is separated by less than half its own height from the bases of the tentacles.

The viscera are in the position usual in the genus, namely, on the right side of the

REPORT ON THE TUNTCATA. 193

branchial sac, and have the normal arrangement — the intestine turning posteriorly after
leaving the stomach, and not anteriorly as in Ascidia — but they are relatively larger,
and extend further anteriorly than in Corella parallelogram/ma. They occupy chiefly
the ventral part of the right side, and extend beyond the branchial sac, the intestine
appearing at the posterior end and ventral edge of the sac when viewed from the Left
side (PL XXVI. fig. 2, /.). In consequence of an anterior twist in the oesophagus, tin:
stomach lies nearly antero-posteriorly (PL XXVI. fig. 3), and the intestine before turning
towards the posterior end, reaches almost to a level with the atrial aperture.

The genitalia branching over the intestine in its anterior part, and occupying the loop,
are, relatively to the alimentary canal, and relatively to the genital mass in Con I In
■parcdlelogranima, and in Abyssascidia, small and inconspicuous. The vas deferens is
conspicuous, running between the stomach and the posterior part of the intestine, and
then between the oesophagus and the rectum towards the atrial aperture (shown as a
dark line in PL XXVI. fig. 3).

Nearly a dozen specimens of this species, all of much the same size, were obtained oil"
Kobe, Japan, at Station 233a ; May 17 to 19, 1875 ; lat. 34° 35' N., long. 135° 10' E.;
depth, 8 to 50 fathoms. Two specimens were also dredged in shallow water off Yoko-
hama, Japan ; and two at Hong Kong, in 1 0 fathoms.

Abyssascidia, Herdman,
Abyssascidia, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 470.

Body oblong, attached by ventral surface. Branchial aperture with about twelve
lobes, atrial with about eight lobes.

Test cartilaginous, soft and transparent.

Mantle thin. A few large distant muscle bands on left side.

Branchial Sac not longitudinally plicated ; stigmata straight.

Dorsal Lamina replaced by languets.

Tentacles simple, filiform.

Viscera on right side of branchial sac. Intestine small. Stomach shorl and wide.

Genitalia forming a round mass situated on the right side of the intestinal loop.

The genus Abyssascidia occupies a position intermediate between Ascidia and Corella,
with both of which it has affinities. It resembles the latter genus in the position
of the viscera, and in the shape and relative size of the intestine. The most striking
peculiarities of the genus are the number of lobes around the apertures and the position
and form of the alimentary canal.

The branchial sac, however, differs greatly from that of Con-lla, and exhibits
the simpler structure found in Ascidia, while the membranes hanging from the trans-
verse vessels and the languets along the dorsal edge of the branchial sac are exactly like
the same parts in Corel/".

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

The genus was formed for the reception of a single species from deep water,
A byssascidia ivy villii.

Abyssascidiawy villii, Herdman (PL XXVII. ).

Abyssaseidia wyvillii, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 470.

External Appearance. — The body is irregularly oblong in shape, rather pointed at the
anterior, and rounded at the posterior, end. It is attached to a small manganese
nodule by the lower (ventral) surface in front of the middle. The lateral edges are rudely
parallel. The body is flattened dorso-ventrally, so that the branchial aperture being
anterior, the atrial is on the upper surface, three-quarters of the way to the posterior
end, and rather to the right of the middle. In consequence of this, more of the left than
of the right side enters into the formation of the upper surface. The branchial aperture
is at the edge, sbghtly to the right of the anterior end, and has twelve or fourteen
lobes ; the atrial has eight or nine lobes, both apertures are sessile.

The surface is smooth. The colour is a very light grey, almost transparent.

Length of the body, 6 cm. ; breadth of the body, 4 cm.

TJie Test is thick ; it is rather solid, but not hard, and is transparent. No vessels are
visible. The test contains only small fusiform cells in the hyabne matrix ; there are no
bladder cells.

Tlie Mantle is very thin, the endostyle and viscera being seen distinctly through it.
A few large distant muscle bands run round the right edge, and extend over the left
side nearly as far as the endostyle. The atrial siphon is prominent, and provided with
fine muscle bands ; the branchial is also muscular, but not projecting.

Tlie Branchial Sac is large, and fills the whole mantle cavity ; it is not" plicated, and
its structure is simple. Every alternate transverse vessel is slightly wider than the
intermediate ones, and here and there the stigmata extend from one larger vessel to the
next, cutting through the intermediate smaller one. The internal longitudinal bars widen
slightly at each intersection with a transverse vessel, but bear no papillae. Tusk-shaped
ducts, to which horizontal membranes are attached, connect the transverse vessels with
the swellings on the internal longitudinal bars. The stigmata are rather wide and

o o o

irregular ; there are about three in a mesh, which is generally nearly square.

The Dorsal Lamina is reduced to a series of conical languets, which are blunt, com-
paratively short, and irregular in size.

Tlie Tentacles are few, distant, small, and filiform ; there are two at each side of the
anterior end of the endostyle, and a few others in the usual circle, but separated by nearly
their own length from each other.

The Dorsal Tubercle is carrot-shaped, tapers posteriorly, and has no visible aperture.

Tlie Nerve Ganglion is elongated. It is placed at a considerable distance from the
dorsal tubercle.

REPORT ON THE TUNIC AT A. 195

The Alimentary Canal is placed on the right side of tin- branchial saCj at the posterior
end, and is relatively small.

The Genitalia form a rounded mass of large size, which lies on the right side of the
intestinal loop at the ventral end.

This interesting form belongs undoubtedly to the Ascidiidse, notwithstanding the
large number of lobes around the apertures! These lobes are mostly well defined, but a
few are rather indistinct, consequently the numbers might be considered for the bran-
chial aperture as either twelve, thirteen or fourteen, and for the atrial as either eight
or nine (PL XXVII. fig. 1). The position of the atrial aperture, rather to the right of
the middle of the upper surface, is curious ; and the area of attachment being nearer the
anterior than the posterior end is also a peculiarity (PL XXVII. fig. 2). The body is
depressed, or flattened dorso-ventrally in place of laterally, and as a consequence the edges
are formed by the right and left sides, and not by the dorsal and ventral lines. The test
is thick and cartilaginous, but soft and very clear ; no vessels nor bladder cells were
observed. When the test is removed the body is seen to be very much smaller 1 than the
cavity in which it lies (PL XXVII. figs. 3 -and 4, and compare with figs. 1 and 2). It
is relatively narrower than when covered by the test, and has the posterior end wide on
account of the large postero-dorsal process, at the extremity of which the atrial aperture
opens (PL XXVII. fig. 3, at).

The mantle is very thin, and the muscle bands on its left side and dorsal edge
(PL XXVII. figs. 3 and 4, rn.b.) are very strong, and bear a considerable resemblance to the
musculature in the genus Corella. The muscle bands on the siphons are fine, and are
more numerous on the atrial than on the branchial. They do not form distinct
sphincters.

The branchial sac is of the simplest possible type, having no folds and not being
longitudinally plicated, the stigmata being straight, and the internal longitudinal bars
bearing no papillae (PL XXVII. fig. 7). The connecting ducts between the transverse
vessels and the internal longitudinal bars are long and curved (PL XXVII. fig. 9, c.d.),
and support between them the delicate horizontal membranes which hang round the
interior of the sac (fig. 7, A.m.).

The languets are short and blunt somewhat finger-shaped processes, placed close
together along the dorsal line, and not all of the same length (PL XXVII. fig. 11, I.).

The endostyle is normal. The tentacles are very slight, and have a curious arrange-
ment. The two pairs placed at the ventral end of the circle, and the two neighbouring
isolated tentacles, are shown in figure 12 on Plate XXVI I., and two others from the
lateral part of the circle are shown in figure 13. The long tapering dorsal tubercle
(PL XXVII. fig. 14, d.t.) lies about three times its own length in front of the elongated

1 The specimen hail Wen in spirit for about six years when examined.
(ZOOL. CIIALL. ESP. — PART XVII. — 1882.) R 26

19(5 THE VOYAGE OF H.M.S. CHALLENGER.

nerve ganglion (fig. 15), which thus comes to be placed at a considerable distance
from the branchial aperture.

The course of the alimentary canal (PL XXVII. figs. 3, 5 and 6) is very similar to
that found in Corella parallelogramma. The narrow oesophagus (PL XXVII. fig. 6, ce.a.)
opens near the base of the branchial sac at the dorsal edge, and runs horizontally (the
branchial aperture being superior) for a short distance, and then opens into the barrel-
shaped stomach (figs. 5 and 6, St.), which has its wall raised externally into about twelve
r< mnded longitudinal ridges, and is situated about half-way across to the ventral edge.
From the opposite end of this stomach the intestine curves ventrally and slightly upwards,
then downwards, and then runs parallel to its first part (PL XXVII. figs. 3, 5 and 6, L),
past the stomach and oesophagus, turns upwards, runs past the oesophageal opening, and
ends in a prominent anus (figs. 5 and 6, a.) not far from the posteriorly placed atrial
aperture. The faeces are brown.

The genital mass is situated, as is usual in the genus Corella, upon the ventral portion
of the intestine, where it turns round posteriorly after leaving the stomach.

The ovary (PL XXVII. fig. 1G, or.) forms the central part of the genital mass, and
the testis occupies the periphery, and consists of pyriform spermatic vesicles (PL XXVII.
figs. 16 and 18, t.v.) full of small spherical cells.

The oviduct and vas deferens emerge from the dorsal and posterior end of the mass,
and course along the superior (anterior) margin of the intestine (PL XXVII. fig. 5, g.d.)
to their termination.

One specimen of Abyssascklia wyvillii was obtained to the south of Australia, at
Station 160; March 13, 1874 ; lat. 42° 42' S., long. 134° 10' E. ; depth, 2600 fathoms;
bottom temperature, 0°"2 C. ; bottom, red clay.

Ascidia, Linnaeus.

Ascidia, Linnaeus, Syst. Nat., 12th Edn. 1766. In part.

Aseidia, 0. F. Miiller, Zoologia Danica. 1780. In part.

Ascidia, Cuvier, Mem. sur les Ascidies, M6m. du Mus., vol. ii. 1815. In part.

Phallusia, Savigny, Mem. sur les Anim. sans Vertebres, pt. ii. fasc. 1. 1816. In part.

Ascidia, Forbes and Hanley, Brit. Moll., vol. i. 1853. In part.

Ascidia, Alder, Observations on Brit. Tunicata, Ann. and Mag. Nat. Hist., ser. iii., vol. xi. 1863.

In part.
Ascidia, Hancock, On the larval state of Molgula, &c, Ann. Mag. Nat. Hist. ser. iv., vol. vi.

1870.
Ascidia and Ascidiopsis, Verrill, Arner. Journ. of Science and Arts, ser. iii., vol. i. 1871.
Ascidia, Heller, Untersuchungen ii. d. Tunicata adriat. Meeres., Abth. 1. 1874.
Phallusia, Kupffer, Jahresber. der Commiss., &c. 1875.
Phallusia, Traustedt, Oversigt over de fra Danmark, &c, Asc. Simp. 1880.
Ascidia and Phallusia, Julin, Becher. sur l'organ. des Asc. Simp. — Sur l'Hypophyse, &c. 1881.

RETORT ON THE TUNICATA. 197

Body attached, sessile, usually oblong or ovate in shape. Branchial aperture

eight-lobed, atrial six-lobed.
Test cartilaginous, but soft and flexible, sometimes thin and membranous; rarely

prolonged into hair-like processes, or covered with sand.
Branchial Sac never folded, sometimes minutely plicated. Internal longitudinal

bars present, and usually papillated ; stigmata straight.
Dorsal Lamina in the form of a plain, or mure or less ribbed and pectinated

membrane.
Tentacles simple.

Viscera placed upon the left side of the branchial sac.
Genitalia in the intestinal loop.

Whether the present genus should be called Ascidia or Phallusia is now a matter of
individual opinion, and it makes little difference which name is finally adopted. Ascidia
seems preferable for two reasons: — (1), it was the name first given, although in a wider
sense than as at present used ; (2), it has been more generally employed than Phal-
lusia.

Baster, in 1762 (Opuscula subseciva, vol. i.), gave the name Ascidium to a species of
Simple Ascidian. This was afterwards changed by Linnaeus to Ascidia, and under that
name all the Simple Ascidians are grouped in the 12th edition of the " Systema Naturae,"
and in 0. F. Midler's " Zoologia Danica."

Savigny, in 1816, divided Linnseus's Ascidia into the four genera — Phallusia, Cynthia,
Boltenia and Clavelina. Of these Phallusia most nearly corresponds with the present
genus, but had wider limits, including the entire family Ascidiidse. Since Savigny's time
Ascidia has been used by some authors and Phallusia by others.

The main objection to using Ascidia is, that when first proposed it included more than
what we now include in the genus, but this same objection holds in regard to Phallus/'"
also ; as used by Savigny, the latter term comprised Cwna and Corella, and was exactly
ecpuivalent to Ascidia as used by Forbes in his " British Mollusca" (1853). In precisely
the same sense, Ascidia has been used since by Alder in 1863, and by Claus in 1876,
and Phallusia by van der Hoeven in 1856, and by Kupffer in 1870.

Hancock (1870) employed Ascidia in the restricted sense in which it is used here,
and has been used by Heller and others ; while Phallusia in the same restricted sense
(i.e., not including Ciona and Corella) has been employed by Kupffer in his " Jahresber.
der Commiss., &c," 1875, and by Traustedt in 1880.

Hence it appears that whether we take the name first applied without regarding the
limits of the genus, or merely the name that was first used in the present restricted sense,
we find that Ascidia has the priority over, and has been rather more generally accepted
than, Phallusia.

IflS

THE VOYAGE OF H.M.S. CHALLENGER.

Ascidia is the largest and best known genus of the Ascidiidaa, and may be considered
as the typical form. In shape it is usually irregularly ovate or elongated antero-posteri-
orly, and it is attached by the posterior end or part of the left side of the body. It is
very rarely 1 covered with incrusting sand and other foreign bodies. Usually the bran-
chial aperture is surrounded by eight lobes and the atrial by six, but the former may
have seven or nine, and the latter five or seven.

The test is usually thick, but soft and flexible, and more or less transparent. In a
typical species (e.g., Ascidia mentula, 0. F. Muller) it is plentifully supplied with blood-
vessels, and the terminal knobs in the outer layers are surrounded by quantities of large
ovate bladder cells (fig. 18, a).

^fTt-

<$

a/.

I© /

.?*■■&

v-- * ;#-\«-

Fig. 18.— Transverse section through the test of Ascidia, showing the matrix in which lie large bladder cells (c) scattered in the inner
layers, and smaller bladder cells (a) near the surface (the left side of the figure), blood-vessels (4) with terminal knobs, and pigment
cells (d) — magnified about 40 times.

In some species (e.g., Ascidia nigra, Savigny) many of the cells become pigmented,
thus colouring the whole test and rendering it opaque. In a few cases the test is very
thin and membranous, and appears to have no vessels.

The mantle is never very thick. It is usually fairly muscular on the right side where
it lies over the branchial sac, but the muscle bands are not arranged according to a
definite system, as they are in many of the Cyntliiidse. There are a number of bundles
which radiate from the bases of the siphons, and some others which cross the anterior and
dorsal region lying between the branchial and atrial apertures. These usually form longi-
tudinally running sets of bundles, which, however, branch and anastomose so as to make
an irregular network. They are crossed at right angles, and obliquely, by a series of more
or less transversely running bands, which terminate at the dorsal and ventral edges, or
very slightly beyond them, as the left side of the body over the viscera is almost or
entirely destitute of muscular fibres. The siphons are very rarely prominent,3 and the
sphincters are usually only of moderate strength.

1 Ascidia involute, Heller, is one of the exceptions.

2 Ascidia longitubis, Traustedt, has both siphons enormously elongated, and Ascidia pyriformis, Herdinan (PI. txxiv.
fig. 3), shows the same condition in a less marked degree.

REPORT ON THE TUNICATA.

199

The branchial sac has never large longitudinally running folds, such as are found in
the Molgulidae and Cynthiidse. The system of internal longitudinal bars is always
present, and is well developed. These tubes, by their intersection with the transverse
vessels, form the meshes visible on the inner surface of the sac (fig. 19), and at the

l.v.

il.

><vvifvmf%jf

V « 9 if if

-tr.

c.d.

Fig. 19. — A Single Mesh of the Branchial Sac of Ascklia, seen from the inside.

tr., transverse vessel ; i.l., Internal longitudinal liar ; l.r., fine longitudinal vessel ; p., papilla ; p1., smaller intermediate papilla ;

c.d., connecting duct ; sg. , stigma.

corners of the meshes the internal longitudinal bars bear usually knob-bke projections or
papillae (fig. 19, p.) projecting into the interior of the sac. In some species {e.g., Ascidia
aspersa, 0. F. Midler, and Ascidia styeloides, Traustedt), these papillae are absent, or very
rudimentary; while in other species (e.g., Ascidia rneridioncdis, Herdman, and Ascidni

l.v.

Fig. 20.— Diagrammatic horizontal section through a Mesh of the Branchial Sac of Ascidia, showing the interior of the transverse

vessel, connecting duct, and papilla at the right hand end.

if., transverse vessel ; l.v., fine longitudinal vessel ; i.l., internal longitudinal bar ; p., papilla ; c.d., connecting duct;

h.m., horizontal membrane.

200

THE VOYAGE OF H.M.S. CHALLENGER.

d&pressa, Alder), a series of smaller intermediate and alternating papillae is present on
the internal longitudinal bars in addition to those at the angles of the meshes.

In the simplest condition the transverse vessels are all of one size, and the interstig-
matic vessels connecting them are placed in one plane, forming a continuous row (fig. 20) ;
but in many species (e.g., Ascidia meridionalis) there are two or more distinct sizes
of transverse vessels, which are usually placed so as to alternate regularly ; and in
some species the fine longitudinal or interstigmatic vessels are arranged so that their
line of insertion into the transverse vessels forms an undulating in place of a straight line
(fig. 21), or is even more irregular (PI. XXIX. fig. 4).

(rough

tr

11

..rd.

Fig. 21. — Diagrammatic horizontal section through a Mesh of the Branchial Sac of Ascidia, showing the arrangement of the fine

longitudinal vessels which causes "minute plication."

tr. ..transverse vessel ; l.v., fine longitudinal vessel ; i.L, internal longitudinal bar ; c.d., connecting duct ; p., papilla ; h.m., horizontal
membrane. " Crest " indicates the highest, and " trough " the lowest part of the undulation.

The result of this arrangement is that the sac, when seen from the inside, or still
better from the outside (PI. XXXI. fig. 5. and PI. XXXIII. fig. 3), where there are no
internal longitudinal bars to obscure the view, seems to be thrown into a series of
minute crimps or plaits, and this is the structure which has been called " minute
plication."

Verrill,1 in 1872, suggested that Ascidia complanata, Fabricius, should form the type
of a new genus, to which he gave the name Ascidiopsis, on account of the remarkable
structure of its branchial sac ; but from the figure given, this structure seems to be merely
the above described minute plication which is found in Ascidia mentuia, Ascidia
virginea, and a number of the oldest known and most typical species of the genus
Ascidia. The plication varies considerably in the degree to which it is present, and also
in its regularity. Usually when the sac is plicated there are several sizes of transverse
vessels, and the smaller sizes may enter into the undulations of the stigmatic vessels,
while the larger ones do not. In this case the appearance of the outer surface of the sac,
when the plication is regular, is that of a number of alternately placed projections and

1 Descriptions of some imperfectly known and new Ascidians from New England, Aiuer. Journ. Sc. and Arts, ser.
ill- , vol. iii., No. 16.

REPORT ON THE TUNICATA.

201

Br.

Its'.

Fig. 22. — Diagram of a dissection of Asculia, from the right side, to show the relatious of the different " tunics " and

cavities, the course of the alimentary canal, &c.
Br., branchial aperture; At., atrial aperture; t.., test ; m., mantle; br.s., branchial sac; 6r..«\, outer surface of branchial sac; en.,
endostyle ; d.L, dorsal lamina ; p.br., peribronchial cavity; in., tentacle; cl., cloaca; ce.a., oesophageal aperture; ty., typhlo-
sole in intestine ; a., anus ; n.g., nerve ganglion ; <jl., neural gland ; (/l.d., duct from neural gland ; >j., genital organs ; g.d., genital
duct.

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

depressions arranged antero-posteriorly between the larger transverse vessels, but not
joinino- across them (PI. XXXIII. fig. 3). In this way a series of shallow pouches is
formed, opening off the peribranchial cavity.

The dorsal lamina varies in its character, from a plain broad membrane with a smooth
edo-e and no markings, to a closely ribbed structure, with the free edge provided with one
or more series of large pointed knob or tooth-bke processes, the larger of which usually
correspond to the ends of the ribs, and are in the same line with the transverse vessels of
the sac.

The tentacles are usually large, and very frequently of several sizes, arranged
symmetrically (PI. XXXIII. fig. 5). Each tentacle is long, tapering and filiform ; it is
triangular in cross section, and is placed so that one of the sides is anterior and the
opposite angle posterior.

The dorsal tubercle is as a rule comparatively simple. The typical form in the genus
has a horse-shoe shape, with the aperture placed anteriorly, and the horns turned slightly
either inwards or outwards, but not coiled spirally, as in most of the Molgulidse and
Cynthiidae.

The stomach and intestine lie upon the left side of the branchial sac, and the usual
arrangement is that shown in fig. 22, p. 201, where the ventrally directed oesophagus leads
into a globular stomach, which reaches to the ventral edge of the body. The intestine,
after emerging from the stomach, runs anteriorly, then dorsally, and then posteriorly
to form a loop (the intestinal loop) which is open posteriorly. It then turns dorsally and
anteriorly again, becoming the rectum which runs forwards near the dorsal edge of the
left side, and completes a. second loop (the rectal loop), which is open anteriorly.

The branched ovary and testis occupy the intestinal loop (fig. 22, g.), and extend over
the adjoining parts of the stomach and intestine, while their ducts run along the pos-
terior and dorsal edge of the intestine and rectum, to open into the peribranchial cavity
anteriorly near the anus.

A renal organ is present in the form of a mass of clear thin-walled and large vesicles,
usually containing concentrically laminated yellow and brown concretions. It occupies
the rectal loop and the adjoining regions of the left side of the body.

Eleven species of Ascidia were collected during the Challenger expedition, and they
were all new to science, with the exception of the aj>parently common West Indian
species, Ascidia nigra, Savigny.

Ascidia challengeri, n. sp. (PI. XXX.).

External Abearance. — The shape of this species is irregularly oblong, with the
anterior end rather narrow ; the posterior, which forms the base of attachment, is slightly
broader, and the dorsal and ventral edges diverge slightly as they run backwards, and
are sometimes curved. The branchial aperture is anterior, terminal, or slightly on the

REPORT ON THE TUNICATA. 203

right side ; it is prominent, and distinctly lobcd. It is directed anteriorly and to the
right side. The atrial aperture is on the dorsal edge, one-fourth to one-third of the
distance from the anterior to the posterior end. It is prominent, is distinctly lobed, and
points more or less anteriorly.

The surface is rather uneven, being seamed by a number of shallow grooves, which
have mostly a longitudinal course. The posterior end of the body, which is usually
prolonged into a more or less uneven base of attachment, has often irregular rough
processes projecting from it. The colour is a dull yellowish-grey, -with occasional darker
patches, especially at the place of attachment.

Length of the body, 17 cm. ; breadth of the body, 5 '5 cm.

Tlie Test is cartilaginous and moderately thick, but soft and flexible. Vessels arc
al mndant.

Tlie Mantle is strong, and the musculature is well developed on the right side of the
body and round the apertures.

The Branchial Sac is strong, and is slightly plicated longitudinally. The transverse
vessels are of two sizes, but these are not arranged with great regularity ; usually several
of the smaller size occur between every two of the larger. The internal longitudinal
bars are strong and regular, and bear large curved papillae at the points of intersection
with the transverse vessels and smaller intermediate ones, which are usually connected by
delicate horizontal membranes. The meshes are slightly elongated transversely, ami
contain each eight to ten stigmata. Occasionally much narrower transverse vessels are
present for short distances, thus forming two rows of small stigmata in a mesh.

The Dorsal Lamina is a broad membrane, strongly ribbed transversely, and having the
edge toothed in some parts and plain in others.

TJie Tentacles are simple, not long but rather stout, and all of one size.

Tlie Dorsal Tubercle is large but simple. It lies in a shallow peritubercular area, and
extends anteriorly almost to the bases of the tentacles. The shape of the tubercle is
ovate, while the aperture is at the narrower anterior end. Both horns are turned to the
right.

This is a large and somewhat variable species, which appears to be common at
Kerguelen Island. In the first part of the Preliminary Eeport it was considered as
being identical with Ascidia mentula, 0. F. Midler, a species to which it is closely albed.

The body is elongated, and in the larger specimens is often curved (PI. XXX. fig. 1),
while in younger examples it has a much more regular form, and is not so elongated
(PI. XXX. fig. 2). In the young individual also the area of attachment at the posterior
end is comparatively small, while in the larger specimens it is much produced and irregu-
larly twisted, extending in one case more than 7 cm. beyond the posterior end of the
body.

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) E 27

204. THE VOYAGE OF H.M.S

Length
(anteroposterior),

1.

14-5

cm.

2

13

cm.

3.

13

cm.

4.

12

cm.

5.

12

cm.

6.

11

cm.

7.

6

cm.

8.

6

cm.

9.

5

cm.

10.

5

cm.

11.

4-8

cm.

12.

4-5

cm.

.S. CHALLENGER.

s of twelve

specimens of this species :-

Breadth

(dorso-ventral).

Length of the posterior
prolongation for attachment

6 cm.

3-5 cm.

6 cm.

7 cm.

6 cm.

3 cm.

6 cm.

2-5 cm.

5 cm.

i

5-5 cm.

8 cm.

3-5 cm.

2-5 cm.

3 -5 cm.

2

2-4 cm.

None.

2 cm.

None.

2-8 cm.

None.

2-5 cm.

None.

The apertures are conspicuous and distinctly lobed (PL XXX. figs. 1 and 2). The
atrial aperture is not distant from the branchial and is always more prominent.

The testis that of a typical Ascidia, and contains numbers -of large oval or spherical
bladder-cells, especially in the outer layers (PL XXX. fig. 3, bl.). Vessels are abun-
dant and branch freely, but their terminal knobs (PL XXX. fig. 3, t.k.) are rather small.

The branchial sac is very like that of Ascidia mentula. It has the same irregularity
in the disposition of the stigmata, as seen from the inside, caused by a sbght longitudinal
plication. The internal longitudinal bars are strong, and with their prominent curved
papillae form a conspicuous feature in the internal view of the sac (PL XXX. fig. 4).
Delicate horizontal membranes are present along the inner edges of the transverse vessels,
extending between the papillae, and also frequently in intermediate positions connecting the
small papilla?.

The dorsal lamina, as may be seen from a glance at figures 5, 6 and 7 on Plate XXX.,
varies considerably in its characters. Figure 6 shows what seems an unusual condition,
where the edge is crenated, and bears a number of small irregularly placed pointed pro-
cesses. The most prominent of these are always placed opposite the terminations of the
ribs. Figure 7 represents the right side of the lamina, near the base.

The dorsal tubercle (PL XXX. fig. 8, d.t.) is very large, and in the specimen
figured was not nearly contained within the shallow peritubercular area. In another
individual which was examined, the peritubercular area was much deeper and more cup-
shaped. It enclosed almost the whole of the tubercle. The anterior peripharyngeal band,
which is in close relation to the posterior end of the dorsal tubercle, lies at a considerable
distance from the dorsal ends of the right and left posterior bands, which turn posteriorly
and converge towards the anterior extremity of the dorsal lamina (PL XXX. fig. 8, p.p.).
The tentacles are comparatively short but stout.

1 This specimen was attached by the left side of the body, and has no posterior prolongation.

2 The posterior prolongation was torn in this specimen.

REPORT ON THE TUNICATA. 205

The viscera are large ; the intestinal loop is narrow, and extends for a considerable
distance anteriorly.

Specimens of this species were obtained at three localities off Kerguelen Island, Station
149, namely, Balfour Bay, January 19, 1874, 20 to GO fathoms, 5 specimens ; Royal Sound,
January 20, 1874, 28 fathoms, G specimens ; and Kerguelen, 10 to 60 fathoms, 2 specimens.

Ascidia vasculosa, Herdman.

Ascidia vasculosa, Herdman, Prelim. Rep., Proc. Roy. Soc. EJin., 1879-80, p. 465.

External Appearance. — The shape is very irregular, and is somewhat quadrangular
and depressed. The anterior end is a little prolonged and narrower than the rest, and
the body is attached by the left side near the base. The branchial aperture is not quite
terminal, being on the right side of the anterior extremity. The atrial aperture is also on
the right side, nearer the dorsal than the ventral edge, and a little in front of the middle.
Both the apertures are rather depressed and concealed.

The surface is very irregular, it is grooved and mammillated, and has Compound
Ascidians, Annelid-tubes, &c, adhering to it. It is of a light yellowish-grey colour, is not
opaque, being rather hyaline at the edges, and showing everywhere numerous blood-vessels
ramifying near the surface. The terminal twigs of the vessels, with their swollen ends,
are a prominent feature.

Length of the body, 9 cm.; breadth of the body, 5"G cm.

The Test is cartilaginous and solid, and varies in thickness from less than 0"5 mm. on
the right side behind the middle to l-5 cm. on the left side near the place of attachment.
The apertures are lobed indistinctly ; the vascular trunks enter on the left side near the
ventral edge, and branch usually cbchotomously, the terminal twigs ending in swollen
knobs. The test shows no bladder cells. It contains the usual small spherical fusiform
and stellate cells, and many minute granides. Crystals or concretions are also present,
generally in the form of short rods and crosses.

This is a specimen from the collection made at Kerguelen Island, of which nothing
remains but the test. This organ seemed to me, however, to be so distinct from that of
the other known species of Ascidia, that I described it in the first part of the Preliminary
Report under the name of Ascidia vasculosa.

The shape is very irregular, having various grooves and projections, and being covered
with several adhering animals. The blood-vessels are the distinctive feature. They are
numerous and of large size, and show very distinctly from the outer surface of the test.
Probably the crystals mentioned in the above description are a post-mortem change,
possibly the result of the long immersion in spirit.

One specimen (the test only) was found at Station 149, Royal Sound, Kerguelen
Island, January 20, 1874 ; depth, 28 fathoms.

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

Ascidia placenta, Herdman (PI. XXXI. figs. 1-3).

A*ci<Uaplar<nta, Herdman, Prelim. Rep., Proe. Roy. Soc. Edin., 1879-80, p. 715.

External Appearance. — The body is elongated, oblong, elliptical or oval in shape, and
is flattened laterally ; the anterior end is slightly the narrower, and the posterior end is
rounded. It is attached by a small area a little posterior to the middle of the left side.
The apertures are both on the right side ; they are sessde, and not conspicuous. The
branchial is nearly median and terminal ; the atrial is a short distance from the dorsal
edge, nearly half-way down from the anterior to the posterior end.

The surface is rather creased by seams running for the most part longitudinally, and
is slightly roughish or velvety.

The colour is a yellowish-grey or horn colour.

Length of the body, 6 "5 cm.; breadth of the body, 4 cm.

The Test is rather thin, soft, and easily torn. It is roughish about the base of attach-
ment. The inner surface is smooth and glistening. Vessels are feebly developed.

The Mantle is moderately muscular.

The Branchial Sac is delicate, and is slightly plicated longitudinally. The transverse
vessels are all of one size. The internal longitudinal bars are moderately strong, and
bear at the angles of the meshes very long curved papillae, connected by delicate transverse
membranes. The stigmata are long and narrow, and are usually wider than the inter-
stiomatic vessels ; there are eight to twelve in a mesh. The meshes are large and rather
longer transversely than antero-posteriorly.

The Dorsal Lamina is not ribbed, or only slightly so in places. Every here and there
a large tooth in the form of a short finger-like process is present, and between these are
usually three or four smaller ones.

The Tentacles are filiform, about twenty-four in number, and all of one length.

The Dorsal Tubercle is longish elliptical in shape, and is placed antero-posteriorly, with
the opening at the anterior end.

This species is much compressed laterally, and as its point of attachment is near the
centre of the left side, it must have lived in a more or less horizontal position, as an
expanded flattened cake-like structure (PI. XXXI. fig. 1). In external appearance it
resembles Ascidia tenera somewhat, but they differ greatly in detafls of structure.

The branchial sac is very delicate (PL XXXI. fig. 2), and the stigmata are long and in
some places rather irregular. The papillae are very large, and are found bent in all direc-
tions. The smaller intermediate ones which are occasionally present may be connected
by delicate transverse vessels, much slighter than the usual ones.

The dorsal lamina is usually devoid of transverse ribs, as represented in figure 3, but
in some parts of its extent very slight ribs are present, running towards the larger
marginal teeth.

REPORT ON THE TUNICA TA. 207

Two specimens were obtained to the south of Kerguelen Island, at Station 150 ;
February 2, 1874; hit, 52° 4' S., long. 71° 22' E.; depth, 150 fathoms; bottom
temperature, l0-8 C; bottom, rock.

Ascidia meridionalis, Herdman (PI. XXXI. figs. 4-8).

Ascidia meridional^, Herdman, Prelim. Rep., Proc. Roy. Soc. Ediu., 1879-80, p. 4G5.

External Appearance. — The shape is somewhat variable ; it is generally oval, the
anterior end being rather narrower than the posterior. The posterior end is rounded, and
the anterior more or less pointed. The body is flattened laterally, and is attached by the
posterior end and part of the left side. The branchial aperture is terminal, at tin-
extremity of a large conical process, the apex of which is inclined ventrally and to the
right ; the atrial aperture is to the right of, or on the dorsal edge, about one-third of
the way down ; it also is on a process, which, however, does not usually project so much as
the branchial one ; it is directed dorsally, anteriorly, and slightly to the right ; the lobes
of both apertures are distinct.

The surface is slightly velvety ; otherwise it is smooth, but more or less creased and
seamed. The colour is light brown or horn colour.

Length of the body, about 1 2 cm. ; breadth of the body, about 8 cm.

The Test is softish, and tears easily, it is from 1*5 to 6 millimetres thick, the left side
being thicker than the right. Vascular trunks enter about the middle of the left side,
near the ventral margin, and large vessels are seen ramifying on the inner surface, which
is smooth and shining.

TJie Mantle is moderately muscular.

The Branchial Sac is slightly plicated longitudinally. Three small transverse vessels
occur between each pair of large ones. The internal longitudinal bars are strong, and
bear short stout papUlee at the angles of the meshes, and also small conical intermediate
ones. The meshes are slightly longer transversely than antero-posteriorly, and contain
each 6 to 8 stigmata. The stigmata are elongate-elliptical in shape.

TJie Dorsal Lamina is broad, and is ribbed transversely ; the margin is serrated.

Tlie Tentacles are simple, filiform, about sixty in number, and placed long and short
alternately.

The Dorsal Tubercle is crescentic in shape, with the horns pointing anteriorly.

This is a large and well marked species ; the form is more or less oval, the anterior end
being the narrower (PI. XXXI. fig. 4). In some of the specimens, however, the shape is
a good deal more irregular than in the one figured. The apertures are placed on large
conical projections, the sides of which are channelled by the grooves leading down from
between the lobes. In one specimen the branchial aperture is only seven-lobed, while

•jus

THE VOYAGE OF H.M.S. CHALLENGER.

in another it is distinctly niue-lobed. A few Sponges, Polyzoa, &c., are attached in some
of the specimens to the left side.

The following list shows the dimensions in twelve individuals of this species : —

Length of Body.

Breadth of Body.

Length of Body.

Breadth of Body

1.

14 cm.

8 cm.

7.

1L5 cm.

7 cm.

2.

12-5 cm.

8-5 cm.

8.

1 1 cm.

7 cm.

3.

12 cm.1

13 cm.

9.

11 cm.

6 '5 cm.

4.

12-5 cm.

8 cm.

10.

8 cm.

4-5 cm.

5.

12 cm.

7 cm.

11.

7-5 cm.

5 "5 cm.

6.

12 cm.

6'5 cm.

12.

5 -5 cm.

3-5 cm.

The test is moderately thick but very soft. The blood-vessels are large and
abundant, and are conspicuous on the inner surface of the left side. Their terminal
twigs in the outer layers have enlarged knob-like ends. Bladder cells are abundant ; they
are very large throughout the inner three-fourths of the thickness, but in the outer fourth
they become smaller and are more closely packed. The ordinary minute fusiform cells
are also present. The mantle is of moderate strength ; the musculature is irregular on
the right side of the body and the anterior half of the left, while it is absent on the
posterior half of the left, over the stomach and intestine.

The branchial sac (PI. XXXI. figs. 5 and 6) is large, completely filling the mantle
cavity. It is slightly plicated longitudinally, and the stigmata are arranged in alternate
bands of narrower and wider ones corresponding with the crests and troughs of the
plications. The large transverse vessels are very wide, and are somewhat encroached
upon by the ends of the narrower stigmata. In figure 5, which shows the outer (atrial)
side of the branchial sac, one of the muscular suspensors or tubes (s.) connecting the
sac with the mantle is seen at the right hand lower corner.

The dorsal lamina (PI. XXXI. fig. 7) is broad but delicate, and the edge is strongly
serrated ; it extends a little more than two-thirds of the way down to where the oesophageal
opening is placed. The tentacles (fig. 8, tn.) are filiform, and the longer ones are very long
and thin, running out to fine terminations.

The nerve ganglion is oblong, of a yellow colour, and gives off two large nerves at
each end — one pair to the branchial and the other to the atrial aperture.

The alimentary, genital, and renal viscera form a large but flat mass upon the
posterior half of the left side. The oesophageal aperture is situated near the posterior end
of the sac, and from it the oesophagus runs posteriorly and ventrally ; the large stomach
continues the curve, running ventrally and anteriorly, and then turns directly anteriorly ;
the intestine, after leaving the stomach, continues anteriorly, then bends dorsally for
a short distance, and then runs back again posteriorly, nearly parallel to the stomach ;
finally it bends forwards, and runs anteriorly and dorsally to end in a wide anus, a little

1 This specimen was not perfect, it must have been of enormous size.

REPORT ON THE TUNICATA. 209

way inside the atrial aperture. In almost its entire course the alimentary canal is concealed
by the genital and renal glands. A system of fine tubules, branching dichotomously,
slightly swollen at the points of division, and ending in elongated enlargements, is
present upon the wall of part of the stomach and intestine. The heart lies along the
ventral edge of the stomach. The faeces in the rectum are of a dark greenish -brown
colour.

The ovary ramifies over the anterior part of the intestine and in the narrow
intestinal loop, and the oviduct is seen distinctly running from the groove between the
stomach and intestine, along the lower edge of the latter, to end near the anus, beyond
which it projects slightly. The testis is composed of numerous small oval or pyriform
vesicles of a pale yellow colour, connected with the terminal twigs of a duct which
branches dichotomously over the intestine. The vas deferens runs alongside the oviduct
as a conspicuous pale yellow tube. The oviduct is very delicate, and lies behind the vas
deferens, partly encircling it.

The renal gland is of great extent, covering almost the entire stomach and intestine.
It consists of a number of vesicles of large size, having in mass a pale brown colour.
Each vesicle is in its outer part perfectly transparent, but it encloses in its centre one
or more rather brilliant yellowish-brown concretions, which are soluble in hydrochloric
acid, and have a concentrically laminated structure, and often a dark brown centre.
Besides these brown concretions, there are also usually present in each vesicle several clear
rosette-shaped bunches of crystals, which may possibly not be urinary deposits, but may
have been formed by post-mortem changes. The vesicles are quite isolated, and com-
municate with no duct.

There are also to be seen scattered through the renal mass a number of small spherical
opaque white bodies, apparently lying quite freely in the surrounding tissues. These
dissolve with effervescence in hydrochloric acid, revealing a brown centre similar to the
concretions mentioned above. This centre also rapidly dissolves, leaving a dark brown
nucleus, which very slowly dissolves, breaking up into a brown del iris which remains
undissolved. These white bodies are probably the ultimate form of the brown concretions
seen in the vesicles.

Several specimens of this species were obtained off the coast of Buenos Ayres, South
America, at Station 320; February 14, 1876 ; lat. 37° 17' S., long. 53° 52' W.; depth.
GOO fathoms ; bottom temperature, 2°'7 C; bottom, hard ground; and two specimens in
the Straits of Magellan, at Station 313 ; January 20, 1876 ; lat. 52° 20' S., long. 68° 0' AY
depth, 55 fathoms ; bottom temperature, 8°'8 C; bottom, sand.

210 THE VOYAGE OF H.M.8. CHALLENGED.

Ascidia nigra, Savigny.

Phallusia nigra, Savigny, M6m. sur les Anim. sans Vert., part ii., 1" fasc. p. 163, pL ii.

fig. 2, pi. ix. fig. 1, 1816.
Ascidia atra, Lesueur, Descr. of several new species of Ascidia, Jour. Acad. Nat. Sc. Philadel.,

vol. iii. part 1, p. 2, pi. i. fig. 2, 1823.
Ascidia nigra, Herdman, Prelim. Rep., Proc. Eoy. Soc. Edin., 1880-81, p. 466.
Phallusia atra, Traustedt, Vestindiske Ascidia; Simplices, Vid. Medd. Nat. For. Kj0benh.,

p. 278, 1881.

At the time when the first part of the Preliminary Eeport was written, I had only
examined a single specimen, from Bermuda, of this curious species. Since then I have
received from the Challenger Office three large specimens, probably from Station 142 (off
the Cape of Good Hope). They are joined into a single mass by the fusion of the tests,
chiefly at the posterior end, so that the appearance of a colony is produced. There seems
to me no doubt that these Challenger specimens are the same species as Savigny's Phal-
lusia nigra and Lesueur's Ascidia atra, although Traustedt (loc. cit.) appears to think
otherwise. I have seen a considerable number of specimens, as in addition to those of the
Challenger expedition, Mr. Moore, the curator of the Liverpool Free Public Museum, has
kindly allowed me to examine the specimens in the collection made by the Rev. H. H.
Higgins during the " Argo " expedition. Some of these, which were collected at Antigua
and Tucacas, are very large.

One of the most striking features of this species is the test, which varies considerably
in shape, and especially in the length and direction of the siphons, but is always of a
very deep blue colour, almost black, and quite opaque. Sections show that this is due to
the presence of very large numbers of rounded pigment corpuscles, each well filled with
small dark blue pigment granules.

The apertures are distinct and prominent, but sometimes there are one or two super-
numerary lobes. The test is thick and strong, but rather brittle ; it contains numerous
blood- vessels. The mantle is fairly muscular on the right side of the body, and the
muscle bands are of a dark colour.

The branchial sac is long, and tapers to a point at the posterior extremity ; it is
plicated longitudinally, and is in some respects rather like that of Ascidia tra7islucida.
The transverse vessels are alternately wider and narrower, and occasional still wider
transverse vessels are present, alternating with from five to nine of the smaller size. The
internal longitudinal bars are strong, and bear each a series of large curved papillae at
the angles of the meshes, and smaller intermediate ones, which are only present in some
parts of the sac. The papilla? are somewhat like those in the branchial sac of Ascidia
falcigera. A number of the blood corpuscles found in the vessels are of a deep indigo
blue colour. This gives a bluish tinge to the whole sac, and to most of the other organs
of the body.

REPORT ON THE TUNICATA. 211

The tentacles are filiform and are few in number ; they are of two .sizes, placed larger
and smaller alternately, and situated rather far apart.

Ascidia nigra seems to be a common and widely distributed species. Lesueur's
specimens were from St. Vincent and (iuadaloupe, Hay of Calicoua ; and Traustedt's from
St. Croix, and St. Thomas; those obtained during the "Argo" expedition were from
Antigua and Tucacas ; and there are some specimens in the British Museum collection
from the Eed Sea. The Challenger specimen from Bermuda is rather small, measuring
about 6 cm. in its greatest length (antero-posterior), and 4 cm. in breadth. Those probably
from Station 142 are larger, being about 10 cm. in length.

One specimen of this species is from Bermuda, shallow water, and three probably from
Station 142, December 18, 1873; lat. 35° 4' S., long. 18° 37' E. ; depth, 150 fathoms;
bottom temperature, 8°"3 C. ; bottom, sand.

Ascidia falciger -a, Herdman (PL XXXII. figs. l-f>).

Ascidia faleigera, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 469.

External Appearance.- — The body is elliptical or nearly round in shape, and is usually
depressed. The area of attachment is large, including pari of the ventral edge and the
entire posterior end, and extending sometimes half-way up the left side. The edge of the
base is often expanded into a thin spreading margin. The apertures are on the upper
(right) side, near the anterior end, and not far apart ; the branchial is terminal or subter-
minal, the atrial is about two-fifths of the way down, and at a short distance from the
dorsal edge. The branchial is almost sessile, while the atrial is slightly prominent ; the
lobes are very distinct, especially those around the atrial aperture.

The surface is smooth and soft, but slightly wrinkled. The colour varies from a light
grey to a pale horn tint ; it is darker at the apertures.

The length and breadth are variable ; as an average may be taken — length of the
body, 5 cm. ; breadth of the body, 4 cm.

Tlie Test is thin all over, except at the base of attachment, wrhere it is greatly thickened,
and has small stones, &c, imbedded in it. Large vascular trunks are visible in this
thickened base, elsewhere the vessels are few and of small size.

The Mantle is moderately muscular, especially on the siphons and down the centre of
the right side.

The Branchial Sac extends to the base of the mantle, and is not longitudinally
plicated. The transverse vessels are all narrow. The internal longitudinal bars are
moderately strong, and bear long tapering papillae, which are curved like tusks, at the
anoles of the meshes ; there are no intermediate ones ; the horizontal membranes are
very broad, and form large flat vesicles occupying the concave sides of the papilla!. The
meshes are square, and each contains three to five regularly arranged stigmata.

The Endostyle is well marked, and of a yellow colour ; it ends abruptly at the base of
the ventral edge of the sac.

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) R 28

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

The Dorsal Lamina is very broad in its posterior half. It is transversely ribbed awl
minutely tuberculated at the edge, a larger process being placed opposite the end of each
transverse rib, and there are generally a few smaller ones between.

The Tentacles are thirty-five to forty in number, they are long and touch at their bases ;
longer and shorter ones generally alternate, but such is not always the case.

TIic Dorsal Tubercle is oval or elliptical in outline. The horns almost meet, and are
not turned in. The aperture is on the right side of the anterior end.

This species varies slightly in external form. Most of the specimens are more or less
depressed, like those figured (PI. XXXII. figs. 1 and 2), and vary in outline from a circular
(fig. 2) to a rudely elliptical (fig. 1) shape. A few specimens, however, are not so much
depressed, but rise in an oblong form, or rather as a sort of truncated pyramid, from
the base to the branchial and atrial apertures, which in that case may be described as
being situated respectively at the ventral and dorsal edges of the anterior end. The
expanded margin of the area of attachment is present in all the specimens, and is
considerably developed in some (PL XXXII. fig. 1) ; it has in most cases grown around
small stones and other foreign objects, which have thus come to be imbedded in the
test.

In size the specimens vary from 3 cm. in length and 2"5 cm. in breadth, to 6'5 cm.
in length and 3 "5 cm. in breadth.

The contrast between the test on the flat, solid, greatly thickened base, and on the
thin, flexible, upper portion of the body is very great ; it becomes a little thicker again
around the apertures. The vessels in the thickened posterior part of the test are very large.
The matrix of the test is hyaline, with small fusiform and stellate cells scattered through
it ; bladder-cells are few, spherical, and rather small in the outer part ; a few concretions,
generally branched, are also present ; probably they have been formed since death.

The siphons of the mantle are rather long, and the atrial is much wider than the
branchial, which is bent towards the ventral edge in the middle of its length. They are
moderately muscular.

The transverse vessels in the branchial sac are very narrow, and in some places are
so encroached upon by the ends of the stigmata above and below as to be reduced
to ziozag tubes no thicker than the longitudinal interstigmatic vessels (PI. XXXII.
fig. 3, tr.).

The long curved fang- shaped or tusk-like papillae are a characteristic feature in this
sac. They are very large as compared with the size of the meshes, and the ciliation of
their convex surfaces is very distinct. The broad horizontal membranes appear to be
stretched over the convex side of the papillae, and attached to their apices, thus forming
the flattened vesicles seen on the under sides of the papillae.

The ribs on the dorsal lamina, especially on its lower broad part (PL XXXII. fig. 4),

REPORT ON THE TUNICATA. 213

are well-marked membranes, which become less marked and die out as they approach
the free edge ; they appear to be continuations of the horizontal membranes stretching
between the papillae.

The tentacles are placed very closely ; the larger ones are of considerable length
(PL XXXII. fig. 5). The others are rather irregular, both in size and arrangement,
although often they are placed alternately, as shown in figure 5.

The neural gland lying under the nerve ganglion is large, flattened, and of a yellow
colour. The dorsal tubercle is very simple, and the aperture is thrown round to the right
side by the anterior prolongation of the left horn (PI. XXXII. fig. 6).

The oesophagus is short, and opens far back in the branchial sac, at the posterior
extremity of the dorsal lamina. The stomach is long and fusiform, and extends ventrally
and anteriorly from the oesophagus. The intestinal loop and the rectal loop are both
narrow, but deep antero-posteriorly. The stomach and the first part of the intestine are
entirely covered by the reproductive and renal glands. The genital ducts form a distinct
line running down the intestinal loop and along the edge of the rectum. The renal
vesicles contain clear yellowish-brown concretions. The ovary is much branched and
ramifies over the right side of the intestine.

At first I was disposed to consider this species as being identical with Verrill's Ascidia
mollis,1 but though closely allied they are undoubtedly distinct. The branchial sacs
especially differ considerably in details. Ascidia falcigera is also somewhat like Ascidia.
dbliqua, Alder, in external appearance, but these species differ in the form and arrangement
of the papillae in the branchial sac.

Eight or nine specimens were obtained in the North Atlantic, to the south of Nova
Scotia, at Station 49, May 20, 1873 ; kit. 43° 3' N, long. 63° 39' W.; depth, 83 fathoms;
bottom temperature, 1°'8 C; bottom, gravel and stones.

Ascidia tenera, Herdman (PI. XXXII. figs. 7-10).

Ascidia tenera, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 467.

External Appearance. — The body is oblong, or varies from oval to oblong in shape ; it
is flattened laterally. The posterior end is rounded, while the anterior end is rather blunt.
The body is attached by the posterior third of the left side. The branchial aperture is
terminal, is directed somewhat ventrally, and is sessile ; the lobes are well-marked ;
the atrial aperture is placed to the right of the dorsal border, about one-third of the way
from the anterior to the posterior end ; it is sessile, and the lobes are well marked.

The surface is soft and somewhat velvety, but marked with slight creases, mostly
longitudinal ; near the apertures, especially the branchial, it is raised into minute pointed
projections. The colour is light brownish-grey or pale horn colour.

1 Descriptions of imperfectly known or new Ascidians from New England (American Journal of Science and Arts,
ser. iii., vol. vii., 1873). This name was pre-occupied, Hancock having named a British species Ascidia mollis in 1870
(Ann. and Mag. Xat. Hist., ser. iv., vol. vi., p. 358).

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

Length of the body, 5 cm.; breadth of the body, 3 cm.

Tlie Test is thin, soft, easily torn, and transparent. Vessels are moderately developed ;
the main trunks enter on the left side near the base.

The Mantle is very thin, the muscular bands are delicate, and the course of the
alimentary canal is visible from both sides.

Tlie Branchial Sac is not plicated longitudinally. There are generally five or seven
smaller transverse vessels between a pair of larger ones. The internal longitudinal liars
are narrow but well marked ; they bear papillae at the angles of the meshes, and smaller,
more nearly conical intermediate ones. The meshes are square, and contain each three
to five stigmata, generally four. The stigmata are elongate elliptical or oblong in
shape, with rounded ends.

The Dorsal Lamina is rather broad, is delicately and rather distantly ribbed trans-
versely and has the edge pectinated ; there are one or two small intermediate teeth
between each pair of slightly larger ones — those opposite the ends of the ribs.

Tlie Tentacles are filiform, they are forty in number, and are of two sizes placed long
and short alternately.

Tlie Dorsal Tubercle is remarkably shallow ; it is basin-shaped, with a wide anterior
aperture ; it is pointed posteriorly, and has the horns scarcely turned in.

This species has the shape of a typical Ascidia, being elongated antero-posteriorly, and
attached by the posterior end of the left side (PI. XXXII. fig. 7).

The dimensions given above are those of the largest specimen, the remaining two being
a little smaller, but with much the same proportions. The specimens differ in shape,
however, when the test is removed ; one individual having the branchial aperture
prominent and placed on a short siphon, while in others it is sessile, and does not project
beyond the rounded anterior end.

The mantle and branchial sac are rather delicate ; in the latter (PL XXXII. fig. 8)
two smaller intermediate papillae are occasionally joined by a narrow vessel dividing the
mesh transversely ; here and there also the stigmata are only half the normal height, so
that a mesh or part of one contains two rows. This condition of the stigmata does not
necessarily coexist with the narrow vessel uniting the small papillse, either may be present
without the other. Both conditions are shown in figure 8 on PL XXXII.

The condition of the dorsal tubercle is remarkable (PL XXXII. fig. 10). The dorsal
ends of the peripharyngeal bands almost meet before turning posteriorly, so that no peri-
tubercular area is formed, and the dorsal tubercle merely lies in the praebranchial zone
at the anterior end of the dorsal lamina. It is very shallow, with a wide opening between
the horns anteriorly.

The viscera upon the left side of the branchial sac are not large. The cesojmagus is
short, opens into the sac far back, and leads to a comparatively small stomach. The

REPORT ON THE TUNICATA. 215

intestine is largo, but the intestinal loop is rather small. The ovary is considerably
branched, and lies chiefly upon the right side of the loop. The spermatic vesicles are of
the usual pyriform shape, and are united in twos and threes at the ends of the dichoto-
mising vas deferens ; they are found chiefly over the intestine in the lower part of the
rectal loop. The genital ducts are conspicuous along the lower edge of the rectum. The
renal vesicles cover the greater part of the left side of the stomach. They are large and clear-
walled, and contain each one or more spherical concentrically laminated brown concretion-.

This species somewhat resembles Ascidia virginea, 0. F. Midler, but is undoubtedly
distinct from it. That species differs from the present one chiefly in its greater length in
proportion to the breadth, its greater number of tentacles, the absence of intermediate
papillae on the branchial sac, the shape of the tubercle, and in the condition of the dorsal
lamina, — all fairly good characters.

Three specimens, one of them in good condition (the one figured on PI. XXXII.
fig. 7), were obtained from the western end of the Straits of Magellan, at Station 311,
January 11, 1876" ; hit, 52° 50' S., long. 73° 53' W.; depth, 245 fathoms; bottom tem-
perature, 7° '7 C; bottom, mud; and two, one of them damaged, were obtained off the
coast of Buenos Ayres, South America, at Station 320, February 14, 1876 ; hit, 37°
17' S., long. 53° 52' W. ; depth, 600 fathoms; bottom temperature, 2C,7 C. ; bottom,
hard ground.

Ascidia translucida, Herdman (PI. XXXIII. figs. 1-6).

Ascidia translucida, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 466.

External Appearance. — The body is ellipsoidal, oblong-ovate, or oblong in shape,
and is not flattened laterally; both ends are rounded. It is attached slightly by the left
side near the posterior end. The apertures are sessile, and are both on the right side, —
the branchial is nearly terminal and median, while the atrial is more than a third of the
way down, and at a considerable distance from the dgrsal edge.

The surface is smooth and glossy. The colour is a very light grey, almost transparent,
and the vascular ramifications show as white markings over the left side and the margins
of the right.

Length of the body, 2-2 cm.; breadth of the body, 1*2 cm.

The Test is moderately thick and solid, and is transparent. The vascular trunks
enter near the centre of the left side ; they are of large size and branch freely ; they are
clearly visible externally, except in the centre of the right side.

T7ie Mantle is thin and membranous.

The Branchial Sac is longitudinally plicated, and shows externally a well-marked
division into pouches. The internal longitudinal bars are strong, and bear rather long
curved papillae at the angles of the meshes; there are no intermediate ones. The trans-
verse vessels are all of much the same size, and the horizontal membranes are broad. The

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

meshes are nearly square, the transverse extent being slightly the greater; each contains
six to eight stigmata.

The Dorsal Lamina is ribbed transversely ; between each pair of ribs a slighter one,
extending only half way to the margin, is generally present ; the edge is plain.

The Tentacles are simple and rather short and stout ; they are thirty to thirty-five in
number, and of two sizes, placed long and short alternately.

The Dorsal Tubercle is serpentiform, greatly elongated laterally, and disposed in a
series of irregular folds ; the horns at the extremities are not coiled.

In the specimen figured (PI. XXXIII. figs. 1 and 2), the vascular ramifications in the
test are very conspicuous ; they show as delicate white lines spreading over the left
(lower) side (fig. 2) and round the margins and the posterior end, but seem to die away
on the right side, in the centre of which none are visible (fig. 1). The other two
specimens in the collection have the vessels in the test more feebly developed, and they
do not form so prominent a feature in the external appearance.

The apertures are distinct but not conspicuous, and their lobes are not well marked.
The atrial aperture is placed very far round on the right side, being nearer to the centre
than to the dorsal edge (PI. XXXIII. fig. 1).

The plication of the branchial sac is very distinctly seen on the external surface
(PI. XXXIII. fig, 3), the pouches being large and clearly marked. The stigmata are not
long, but are often pointed at their ends ; shorter and more irregular ones are frequently
present. The papillae at the angles of the meshes are large (PI. XXXIII. fig. 4), and
have wide horizontal membranes attached to them.

The dorsal lamina is narrow and plain edged, but is distinctly ribbed transversely
(PI. XXXIII. fig. 6) ; about half the ribs are slighter than the others, and do not extend
to the free edge.

The condition of the dorsal tubercle is very remarkable (PL XXXIII. fig. 5). Instead
of forming a single large curve, with the ends more or less coiled, as is usual in the
Ascidiidae, it has a serpentine course, being thrown into a series of folds, and having its
long axis directed transversely (parallel to the peripharyngeal bands). The tubercle lies
in a shallow and wide peritubercular area, with a narrow but deep diverticulum extend-
ing posteriorly from its central part (PI. XXXIII. fig. 5).

Three specimens of Ascidia translucida were obtained at Kerguelen Island, January
1874 ; depth, 28 fathoms.

Ascidia cylindracea, Herdman (PI. XXXIII. figs. 7-9).

Ascidia cylindracea, HurJman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1879-80, p. 714.
External Appearance. — The shape is oblong and nearly cylindrical ; the posterior
end is rounded and wider than the truncated anterior end ; the ventral edge is nearly

REPORT ON THE TUNICATA. 217

straight, while the dorsal is slightly concave. The body is attached by the posterior end
and the lower half of the left side. The apertures are both at the anterior end, they are
distinct, and the lobes are well-marked ; the branchial is towards the ventral edge, and
sessile ; the atrial is on the dorsal edge, forming a slight rounded projection.

The surface is smooth, but slightly creased. The colour is a light yellowish-grey.

Length of the body, 2 cm.; breadth of the body, 1*2 cm.

The Test is of moderate thickness, it is transparent, and shows vascular ramification.-.

Tlie Mantle has a well-marked musculature.

The Branchial Sac is extremely delicate, and is not plicated. The vessels are all very
slender, and the transverse vessels are of much the same size throughout ; the internal
longitudinal bars are narrow, but well-marked, and have minute papillae at the corners of
the meshes, and connected by very narrow horizontal membranes. The meshes are nearly
square, the antero-posterior extent being generally slightly the greater. The stigmata
are long and narrow ; they are very regular, and are placed three or four in a mesh.

The Dorsal Lamina is narrow, has a plain edge, and is scarcely ribbed ; at the base a
number of convoluted ribs commence, but they die out before reaching the edge.

The Tentacles are filiform ; they are very long and numerous, with their bases almost
touching.

This is a very elegant little species, it is well-shaped, stands erect, and is semi-trans-
parent. The projection of the atrial aperture causes a slight concavity in the dorsal
edge, and adds to the width of the blunt anterior end (PI. XXXIII. fig. 7).

The branchial sac (PI. XXXIII. fig. 8) is very regular, and is the most delicate one
known in the genus Ascidia ; the stigmata are long and are closely packed, reducing the
transverse and fine longitudinal vessels to a very small size. Occasionally the stigmata
break through a transverse vessel for a short distance, and extend for twice the usual
length (see fig. 8, near i. I.). The internal longitudinal bars are slight, but distinct and
very straight. The papilla? at the angles of the meshes are minute but rather thick ; they
are connected by very narrow horizontal membranes, closely attached to the transverse
vessels. Occasionally very minute intermediate papillae are present on the internal
longitudinal bars for a few meshes ; they are also connected by fine horizontal membranes
(PI. XXXIII. fig. 8, tr.'), which span the uninterrupted stigmata, a fine transverse vessel
not being formed.

The dorsal lamina is narrow, and has a plain edge (PI. XXXIII. fig. 9). A number
of ribs, commencing at the ends of the transverse vessels of the branchial sac, form
thickened convoluted bands on the inner part of the lamina, but they die out long before
reaching the- edge ; in some parts they are hardly so well marked as is represented in figure 9.

In this specimen the entire lamina is distinctly marked by a network of capillary
ramifications, which are engorged with blood corpuscles of a reddish-brown colour; they

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

are especially prominent in a band running along the lamina in about the middle of its
breadth (PI. XXXIII. fig. 9).

I was unable to make out the condition of the dorsal tubercle without cutting up the
single specimen in the collection more than seemed proper.

One specimen of Ascidia cylindracea was trawled off Twofold Bay, Australia, at
Station 163 ; April 4, 1874 ; lat. 36° 56' S., long. 150° 30' E.; depth, 120 fathoms.

Ascidia despecta, Herdman (PL XXXIII. figs. 10-12).

Ascidia despecta, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 715.

External Appearance. — The shape is oval, the anterior end being narrow while the
posterior is wider and rounded. The dorsal edge is rather more convex than the ventral.
The body is somewhat compressed laterally and is attached by the posterior half of the
left side. The branchial aperture is terminal, or almost so ; the atrial is not distant,
being on the dorsal edge, about one-fourth of the way from the anterior to the posterior
end ; both apertures are sessile and not conspicuous.

The surface is covered with small soft projections, giving it a rough appearance. The
colour is grey.

Length of the body, 17 cm.; breadth of the body, 1 cm.

The Test is thin, and nearly transparent, showing fine vascular ramifications.
The main trunks enter near the centre of the area of attachment. At the posterior end
of the left side the test is prolonged into a few short tufts for attachment.

TJie Mantle is of moderate thickness.

The Branchial Sac is not plicated longitudinally, and it is rather strong. The
transverse vessels are narrow, and are all of much the same size. The internal longi-
tudinal bars are stout, and bear large roddike papillae at the corners of the meshes ; there
are no intermediate ones. The meshes are slightly longer transversely than antero-
posteriorly ; each contains three to five stigmata, generally four.

Tlie Dorsal Lamina is wide, and is transversely ribbed ; the ribs form rather large
projections on the free margin, which is otherwise plain.

TJie Tentacles are large and numerous, about twenty to twenty-five in number ; they
are all of one length.

This is a soft, roughish, dull grey species, of an ovoid form, with inconspicuous
apertures. It is semi-transparent, the outline of the mantle showing through the test
pretty distinctly (PI. XXXIII. fig. 10).

The branchial sac is rather strong, the stigmata being small and the vessels thick
(PI. XXXIII. fig. 11). The transverse vessels are all of one size, and the stigmata are
regular, short, and elongate-elliptical in shape. The papilla? are rod-shaped, stout, and
prominent.

REPORT ON THE TUNKATA. 219

The dorsal lamina is wide and the ribs are strong ; like those on the dorsal lamina of
Pachychlcena obesa, they rather increase in size as they approach the free margin, on
which they form considerable projections (PL XXX 111. fig. 12).

I was unable to determine the nature of the dorsal tubercle without injuring the
unique specimen.

One specimen of Ascidia despecta was obtained at Kerguelen Island, in January 1874.
from a depth between 10 and 100 fathoms.

Ascidia pyriformis, Herdman (PL XXXIV. figs. 1-6).

Ascidia pyriformis, Herdman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1879-80, p. 468.

External Appearance.— This species is irregularly pear-shaped ; the anterior end is
narrow and pointed, the posterior is broad and rounded. It is attached by a small area
near the posterior end of the left side. The branchial aperture is terminal, and is placed
on a long, somewhat conical projection, turned dorsally ; the sides of this projection are
channelled by eight grooves leading down from between the lobes of the aperture. A
strong elevated ridge extends from the base of the branchial projection along the anterior
part of the dorsal edge. The atrial aperture is sessile, and is placed at the posterior
extremity of this ridge, being about half-way from the anterior to the posterior end, and
directed posteriorly.

The surface is irregular ; it is slightly rough, and is prolonged into a few short
thickish tufts for attachment at the base ; the globular posterior end is incrusted with
sand and shell fragments. The colour is a dull dirty grey.

Length of the body, 5 cm. ; breadth of the body, 3 cm.

The Test is remarkably thin, except on the siphons and the ridge connecting them,
the latter being very thick.

The Mantle is moderately muscular over the right side of the body and on the siphons ;
it is membranous over the large distended left side. The body, when the test has been re-
moved, is very peculiarly shaped. The right (branchial) side is flat, narrow, and elongated
antero-posteriorly ; while the edges of the mantle forming it are produced into a thin
margin, which runs out at intervals, especially round the posterior end, into fine points
attached to the inner surface of the test. The left (visceral) side, on the other hand, is large,
globular, and distended, extending beyond the branchial ana laterally, but not reaching
so far posteriorly. The siphons are long and narrow, the branchial is terminal, and is
directed anteriorly ; the atrial is about hall-way from the end of the branchial siphon to the
posterior end of the body, and is directed dorsally and a little anteriorly. A crested ridge
extends from the base of the branchial to the base of the atrial siphon, and similar
crested ridges extend down both siphons from the lobes round the apertures. The pro-
jecting points of these ridges are received into minute pits on the inner surface of the test.

The Branchial Sac is of moderate size ; it is long, pointed at the dorsal edge of the

(ZOOL. CUALL. Exr. — PART XVII. — 1882.) R 29

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

lower end, and longitudinally plicated. The transverse vessels are narrow, and all of
much the same size. The internal longitudinal bars are strong, and the papillae are
large, but of one size only. The meshes are square, and contain each three or four
stigmata.

Tie Endostyle is conspicuous, and terminates at the base of the ventral edge of the sac.

The Dorsal Lamina is closely ribbed transversely, and the margin is bluntly serrated.

The Tentacles are very numerous and crowded ; they are long and slender, varying
in thickness, but all of much the same length.

Tie Dorsal Tubercle is very comjjlicated, and occupies a deep triangular perituber-
cular area. It forms an irregularly curved and coiled pattern, with no obvious horns.

This is a very remarkable species, and in external appearance (Plate XXXIV. figs.
1 and 2) is distinctly pyriform. The dimensions given above are those of the smaller
specimen; the other one measures 7 '5 cm. in length, and 4 cm. in breadth; it has
several Ascidians and a few other animals adhering to its test.

The greater part of the test is remarkably thin and easily torn ; on the elevated ridge,
however, between the siphons (PL XXXIV. figs 1 and 2), it is very thick. In one of the
specimens a Crenella was found imbedded in this part of the test.

The body, when removed from the test, has a most characteristic appearance (PL
XXXIV. fig. 3). The siphons are long, narrow, and echinated, the branchial measuring
1*2 cm., and the atrial 0"8 cm. in the smaller specimen, while in the larger they are 1*8 cm.
and 1"4 cm. respectively.

On the right side of the body there is a " branchial area," defined by the extension of
the mantle into a sort of free crenated border, the points between the crenations being
produced into longer or shorter sharp processes. The ventral part of this branchial area is
raised into a smooth rounded pad (PL XXXIV. fig. 3). This, at the anterior end, joins an
irregular collar which surrounds the base of the branchial siphon, and is continued as a
crested ridge along the dorsal edge to the base of the atrial siphon, lying under the
prominent ridge which was noticed as running between the two siphons in the description
of the external appearance. The large, globular, visceral side, when viewed from the
right, appears outside the branchial area dorsally, and more especially ventrally.

The plication of the branchial sac is not well marked, and produces, as seen from
the inside (PL XXXIV. fig. 4), merely a little irregularity in the position and direction of
the interstigmatic vessels. The slanting direction in which the transverse vessels run in
the part of the branchial sac figured (fig. 4) is not constant, but was observed in one part
of the branchial sac.

The condition of the dorsal tubercle is very remarkable. The peritubercular area is
triangular and deep, and its cavity is entirely occupied by a convoluted dark marking
(PL XXXIV. fig. 5, d.t.), which appears to represent the dorsal tubercle. The

REPORT ON THE TUNICATA. 221

tentacles are numerous, and a little irregular, lmt not of two sizes arranged symmetrically.
The dorsal lamina has its ribs very closely placed (PI. XXXIV. fig. 6), and the edge is
distinctly serrated.

Two specimens of this curious species were found at Port Jackson, Australia, at a
depth of 6 fathoms.

Pachychhvna, n. gen.

Sub-genus Pachychlmna, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 461.
Body attached, sessile. Branchial aperture eight-lobed, atrial six-lobed.
Test cartilaginous, very thick, solid and opaque.
Branchial Sac longitudinally plicated. Internal longitudinal bars bearing large

papillae at the angles of the meshes. Stigmata straight.
Dorsal Lamina in the form of a membrane.
Tentacles simple.
Viscera large, placed on the left side of the branchial sac.

In the first part of the Preliminary Report, I distinguished the three species forming
the present genus from the other species of Ascidia, on account of the remarkable thickness
and solidity of the test. This feature suggested Pachychlmna as an appropriate sub-generic
title. As, however, I have not recognised any other sub-genera among Simple Ascidians,
and as it is objectionable to introduce new grades into classification, unless absolutely
necessary, it will be more convenient to consider Pachychlmna of generic rank, at least
until some form is found which links it to Ascidia. That such a form may be found I
have no doubt. Pachychlcena and Ascidia are closely allied, and although the specimens
of the two genera in the Challenger collection are clearly distinguishable, it is easy to
imagine a species, or a series of species, uniting their characters, and forming a gradual
transition from the one to the other.

The three species of Pachychlcena described below agree in the following particulars : —
The body is sessile and attached, but of different shapes. The test is thick and opaque,
and of a firm cartilaginous texture. The branchial sac is longitudinally plicated, and
is of considerable thickness. The meshes are transversely elongated (PI. XXVIII.
figs. 2 and 7, and PL XXIX. fig. 4), and have large papillae at their angles; no smaller
intermediate papillae are present. The specimens of two of the species were all more or
less injured, so that the exact determination of the body form is impossible, but the single
specimen of the remaining species, Pachychlama oblonga, is in perfect condition.

Pachychlcena oblonga, Herdman (PI. XXIX. figs. 1-9).

Pachychlama oblonga, Herdman, Prelim. Pep., Proc. Roy. Soc. Edin., 1879-80, p. 461.
External Appearance. — The body is irregularly oblong in shape, widest about the
middle, and narrowing somewhat towards the anterior end, which is obtuse and flattened ;

•222 THE VOYAGE OF H.M.S. CHALLENGER.

the posterior end is rather drawn out, and is attached to the interior of a large bivalve
shell, which is in a three-quarters closed condition, constricting the test of the Ascidian.
The branchial aperture is not terminal, but is placed on the right side near the ventral
v(\<u\ and about one-fifth of the distance from the anterior end to the point where the body
suddenly narrows at the mouth of the shell ; it is directed ventrally, posteriorly, and to
the right. The atrial aperture is on the right side, near the dorsal margin, and slightly
anterior to the branchial aperture ; it is directed dorsally and anteriorly.

The surface is smooth but mammillated very strongly on the anterior half and the
right side, especially near the branchial aperture, where a few more sharply cut papillae are
visible.

The colour is a light smoky brown, rather deeper in tint at the anterior end.

Length of the body, 8 cm. ; breadth of the body, 4 cm.

The Test is cartilaginous, thick, and of a light greyish -brown colour throughout.
Vascular trunks enter the test on the left side about half-way down, and large vessels are
seen ramifying on the inner surface ; dark-coloured terminal twigs with swollen ends are
very numerous in the outer layer. Elliptical cells, partly filled with pigment, are numerous
throughout the whole test. Bladder cells are few and of small size ; in the peripheral
layers around the ends of the vessels, however, they are crowded, but very small.

The Mantle is moderately thick and muscular.

The Branchial Sac is longitudinally plicated. The transverse vessels, which are all
nearly of one size, divide the grooves formed by the plication into rows of pouches, which
are rather irregularly placed, and have no relation to the internal longitudinal bars. The
meshes are transversely oblong, and contain each about eight to ten stigmata. The papillae
are large and expanded.

The Dorsal Laminais ribbed transversely, and is strongly pectinated at the margin, a
rib running out to the apex of each tooth.

The Tentacles are numerous and filiform ; there are sixty-two large ones, and about the
same number of very minute intermediate ones. These last are so small as to be easily
overlooked ; usually one is placed between each pair of large tentacles, but in some spaces
there appears to be none.

The Dorsal Tubercle is large, and irregularly oval in outline ; the right horn is
turned outwards and the left horn inwards.

This is a well characterised and rather peculiar species. The elongated posterior
portion of the test is probably accidental and due to the position of the animal in the
interior of a shell (PL XXIX. fig. 1). Seen from the ventral aspect (PL XXIX. fig. 2), it
seems as if the anterior end had been bent over towards the right side, thus accounting
for the lateral position of the branchial aperture. The atrial aperture is only four-lobed,
1 tut this may be an individual peculiarity.

REPORT ox Tin: TCNICATA. 223

The surface, especially towards the anterior end, is raised into a series of strongly
marked projections, very similar to those seen in Ascidia mammillata.

The test owes its dark colour partly to the small pigment cells (I'l. XXIX. fig. 3,p.c.)
which are scattered so plentifully through its substance, and partly, especially in the
peripheral part, to the vessels, which are very dark in colour. In the outer layer
(PI. XXIX. fig. 3) the swollen terminal knobs of the small twigs form a dark band. The
bladder cells (fig. 3, bl.) are very small.

The branchial sac has a characteristic appearance ; this is chiefly due to the large papilla?,
which are shaped like paddles or La Crosse bats (PI. XXIX. figs. 4 and 5), when seen
from the side, but are simply rod-like or tapering when seen from above (figs. 4 and 6). The
whole sac is strongly plicated, but the crests and troughs are very short, as none of the
transverse vessels enter into the plication. There are wide membranous connecting ducts
(PI. XXIX. figs. 5 and 6, c.d.), which unite the internal longitudinal bars to the trans-
verse vessels. The endostyle is normal.

The teeth on the free margin of the dorsal lamina are large and rather close together,
and the ribs are distinctly continued out to their points (PI. XXIX. fig. 7, d.L).

The small intermediate tentacles (PL XXIX. fig. 9, tn.1) are curious ; they are very
minute in comparison with the others. They are present in the great majority of the
interspaces, but are wanting in a few of them, one of which is seen in figure 8, imme-
diately above the dorsal tubercle. The peritubercular area is shallow.

One specimen, in excellent condition, was obtained off East Moncceur Island, Bass
Strait, at Station 1G2; April 2, 1874; depth, 38 to 40 fathoms; bottom, sandy.

Pachychlcena obesa, Herdman (PI. XXVIII. figs. 1-5).

Pachychlcena obesa, Herdman, Prelim. Rep., Proc. Roy. Soc. EJiu., 1879-80, p. 4G2.

External Appearance. — The shape of this species is unknown, on account of the
absence of the greater part of the test ; it was probably oval or irregularly spherical, and
the anterior end must have been broad and irregularly rounded. The apertures are not
distant, they are fairly conspicuous but depressed.

The surface is smooth and slightly mammillated. The colour is a dark earthy brown.

Length of the body, probably about 10 cm. ; breadth of the body, about 6 em.

The Test is cartilaginous, thick (8 mm.), solid, rigid and opaque; vessels are visible
on the internal surface. It contains also numerous pigment cells and some bladder cells
in the outer layers.

The Mantle is thick on the right (branchial) side of the body, and on the siphons,
but is not very muscular ; it is membranous on the large distended left (visceral) side.
The siphons are long and rather narrow.

The Branch ud Sue is long and narrow, and pointed at the posterior end ; it is longi-

22-1 THE VOYAGE OF H.M.S. CHALLENGER.

tudinally plicated, and the grooves are cut up into pouches which are seen clearly on the
external surface. The transverse vessels are usually larger and smaller alternately. The
internal longitudinal bars are strong, and bear large, irregular, often cleft or lobed papillae.
The meshes are transversely oblong, and each contains about six stigmata.

The Dorsal Lamina is ribbed transversely ; the ribs are rather wide, and project in the
form of small teeth on the free margin.

TJie Tentacles are filiform, slender, and of two sizes, placed large and small alternately;
they are probably thirty to thirty-five in number.

This species seems closely allied to the last described one (PachycMcena oblonga), but
on account of the imperfect condition of both the specimens in the collection, many of the
characters could not be determined. The small portion of the test remaining, suggests
that the shape was more or less spherical, at least as far down as the place of attachment.
The anterior end is broad. The apertures in place of being prominent are depressed
(PI. XXVIII. fig. 1), and in neither of the specimens can the number of lobes around them
be determined. The depression of the apertures can scarcely be due to contraction, on
account of the excessive thickness and rigidity of the test (PL XXVIII. fig. 1).
Probably the depression was advantageous in rendering the test at the margin of the
opening less solid, and thus permitting a certain amount of motion around the apertures.

The test contains many ellipsoidal pigment cells, varying from -g-j^ to -5^ of a
millimetre in their long diameter ; they are very regular in outline, and contain each one
or more strongly refracting circular bodies, and some granular dark yellow pigment.
These are thickly scattered throughout the test. Bladder cells are present in the outer
layers, where the terminal twigs of the blood-vessels are also seen, generally filled with
yellow corpuscles.

The mantle differs greatly in its thickness on the two sides of the body. It is thick
on the siphons, which are necessarily long and narrow (PI. XXVIII. fig. 1).

The branchial sac has a very different appearance according as it is viewed from the
inside (PL XXVIII. fig. 2) or the outside (PI. XXVIII. fig. 3). Internally the internal
longitudinal bars and their curiously shaped papillae are the most prominent features ; the
plication of the stigmatic part is also visible, but the pouches are indistinct (PL XXVIII.
fig. 2). Externally, on the other hand, the pouches are the most evident characteristic (PL
XXVIII. figs. 3 and 4), while the internal longitudinal bars are not seen. The transverse
vessels are of two sizes, and the smaller ones enter into the longitudinal plications, while
the larger ones interrupt it, hence the crests and troughs extend each across two meshes
(PL XXVIII. fig. 4), and the pouches contain each two rows of stigmata (figs. 3 and 4).

The ribs on the dorsal lamina (PL XXVIII. fig. 5) are broad and band-Like, and
rather increase in width as they approach the free margin, from which they project as
small teeth.

REPORT ON THE TUNICATA. 225

The branchial aperture is so damaged in both specimens that it is impossible to make
out the exact number of tentacles and the condition of the dorsal tubercle.

Two specimens, both more or less injured, were obtained off East Moncceur Island,
Bass Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sandy.

Pachychlama gigantea, Herdman (PL XXVIII. figs. 6-11, and PL XXIX. fig. 10).
Pachychlcena gigantea, Herdman, Prelim. Rep., Proc. Roy. Soc. EJin., 1879-80, p. 463.

External Appearance. — The shape of this species, as far as can be made out, is
irregularly oblong, the right side being larger than the left. Probably the body is
attached by the posterior part of the ventral edge. The branchial aperture is eight-lobed,
terminal, and placed on a large irregularly rounded projection turned towards the left side
The atrial aperture is six-lobed, and is also on a large projection, situated on the dorsal edge ;
from one-third to half-way down from the anterior to the posterior end. The lobes of
both apertures are irregular, but prominent.

The surface is very irregular, and in some places is almost covered by foreign bodies.
The colour is a warm yellowish-grey.

Length of the body, about 12 cm.; breadth of the body, 5 to 7 cm.

TJw Test is cartilaginous, very thick (varying from 2 mm. to 4 cm.), solid, rigid, and
opaque ; it is white in mass with a hyaline tint where thin, and yellowish -grey on the
external surface. Large vessels ramify in the inner laj^er ; the vascular trunks probably
enter the test at the base of the right side towards the ventral edge. The terminal twigs
of the vessels are sometimes slightly swollen, but scarcely knobbed ; in some places they
are almost covered by bundles of rod-like or tapering yellowish crystals. The bladder
cells are very small, and are abundant in the outer part of the test around the small
vessels, where yellow pigment cells are also present.

The Mantle is strongly muscular over the right side and on the siphons, while on the
left side it is membranous. In several places, especially between the siphons and at the
anterior extremity of the endostyle, it is marked with dark red.

The Branchial Sac is very thick, coarse, opaque, and of a brown colour. It is longi-
tudinally plicated, and has the grooves broken up into pouches by the larger transverse
vessels. On the external aspect of the sac certain very wide transverse vessels are
connected by equally wide, irregularly placed longitudinal vessels, thus forming an
external network of quadrangular meshes, each of which contains about four rows of
stigmata. The internal longitudinal bars are stout and bear strong conical papillae. The
meshes are much elongated transversely, and each contains twelve to twenty stigmata.

TJie Endostyle is not conspicuous, it is yellowish, with a dark red line down each side.

Tli e Dorsal Lamina is wide, and is strongly ribbed transversely, but not pectinated.
It becomes wider and thinner as it approaches the oesophageal aperture, and then narrows
again rapidly after passing it.

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

The Tentacles are long and stout, they are situated on a very strong muscular ring,
and are about sixty in number; they are all of much the same size, a few are slighter
than the rest, but are not placed regularly.

Tlie Dorsal Tubercle is cordate and very large (measuring 3 "5 millimetres antero-
posteriorly) ; the horns are very long, and are both coiled inwards spirally.

Tlte Alimentary Canal is wide. The oesophageal opening is situated at about three-
quarters of the distance from the anterior to the posterior end of the branchial sac.

This large species has a characteristically solid and cartilaginous test, and may be con-
sidered the type of the genus Pachychlcena. In both the specimens part of the ventral edge,
the posterior end, and a portion of each side is wanting. Still enough remains, taking both
sj)ecimens together, to enable us to form a pretty complete idea of the original shape and
proportions (PL XXVIII. fig. 6, which is formed by combining parts of the two).

Some parts of the surface are incrusted with a brownish Alga, while Polyzoa, Hydroids,
Cirripedes, Compound Ascidians, &c, adhere to or are imbedded in the substance of the
test. The proportions of the two specimens vary slightly ; they are as follows : —

Length of the body.

Greatest breadth.

Distance from the centre of the
branchial to the centre of the
atrial aperture.

A. 1 2 cm.

(Dorso-ventral) 7 cm.

4-5 cm.

B. 124 cm.

(Right to left side) 5'8 cm.

7 cm.

The test, which is probably the thickest and most solid known among Simple Ascidians,
is light-coloured throughout ; it contains numerous blood-vessels, and, in the outer layers
small bladder cells and yellow pigment cells. The crystals found on the vessels in the
test are rod-like or more irregular, large and of a distinct yellow colour on the larger
branches, while on the terminal twigs they are smaller, tapering, disposed in radiating
bunches, and generally colourless (PI. XXIX. fig. 10). I think it is probable that all
these deposits are due to post-mortem changes, caused possibly by the alcohol, and that
they do not exist in the living test.

The body when removed from the test is so shrunken as only to occupy about
half its cavity.1 The siphons are very long, especially the branchial, and diverge at
an angle of more than 90°. The right (branchial) side of the body is flat, while the left is
enormously developed, the viscera forming a large projection. In consequence of this the
body appears to have three sides, — a right and two left (one dorsal and the other ventral),
— or in other words, is roughly triangular in transverse section. The cloaca is filled
with light grey, gelatinous fsecal matter.

The branchial sac is peculiarly thick and opaque, and the wide network of larger vessels
on the external surface (PL XXVIII. fig. 8, e.l. and tr.) gives it a very coarse appearance.

1 This is after about six years' immersion in alcohol.

REPORT ON THE TUNICATA. 227

The longitudinal plication and the formation of pouches is very irregular, and as usual
is more evident on the outer than on the inner surface of the sac. The strong internal
longitudinal bars and their stout papillae make the meshes seem smaller than they really
are, an effect which is increased also by their great transverse elongation (PI. XXVIII.
fig. 7) ; the stigmata, however, are of a fair length. The connective ducts, between the
external network of the branchial sac and the vessels of the mantle, are very wide, and are
compressed so as to appear like flat bands.

The dorsal lamina is wide and strong, but it is not toothed (PL XXVIII. fig. 11).
The tentacles (figs. 9 and 10, tn.) are numerous and very large. They spring from a
projecting pad, which forms a ring round the base of the branchial siphon. The dorsal
tubercle (PI. XXVIII. fig. 10) is very large, and lies in a triangular peritubercular area. It
is peculiar, on account of the extent to which the horns are coiled ; the two spirals fill the
whole internal area of the organ.

The viscera upon the left side of the branchial sac are large. The alimentary canal
has the usual course, but the intestinal loop extends for a considerable distance anteriorly,
and is bent round dorsally so as almost to meet the rectum, and thus enclose a large circular
area which is occupied by a mass of renal vesicles. The genital organs are on the
intestinal loop in its most anterior part. Their ducts are conspicuous along the posterior
edge of the terminal part of the intestine.

Two specimens of this large species were obtained at Simon's Bay, Cape of Good Hope,
in from 10 to 20 fathoms.

Hypobythius, Moseley.

Hypobythius, Moseley, On two new Forms of Deep-Sea Aseidians, obtained during the Voyage of
II. M.S. Challenger, Trans. Linn. Soc., ser. ii., Zool., vol. i. p. 287.

Body cup-shaped or pyriform, pedunculated, attached. Apertures circular, not

Test cartilaginous, but soft and thin.

Branchial Sac not folded, and with no internal longitudinal bars. Stigmata small,

rounded, and irregularly placed.
Dorsal Lamina a plain membrane.
Viscera forming a compact elongated mass on the dorsal edge of the branchial sac.

This genus was founded by Moseley in 187(1, but was no1 characterised apart from the
description of the single species then known, Hypobythius calycodes. A damaged speci-
men of a second species, Hypobythius moseleyi, was found recently in the collection, and is
described below.

There is considerable difficulty in referring this remarkable uvuus to its proper position,
and possibly it ought to he made the type of a fifth family of Ascidia? Simplices, the Hypo-

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) R 3u

•_'-_S THE VOYAGE OF H.M.S. CHALLENGER.

bythiidse. It certainly has no near affinities with either the Molgulidse or the Cynthiidse,
and I have placed it here amongst the Ascidiidse because we have no evidence that it
possesses the power of reproducing by gemmation. Setting this negative character aside,
the genus seems to me to be more closely allied to the Clavelinidse than to the Ascidiidse,
and if allowed to remain in the latter family, must be regarded as an abnormal member,
not conforming to some of the most important characteristics, and displaying features
which show it to be an annectent form between the Ascidiidse and the Clavelinidae. It
agrees with the latter family in having the apertures circular and not lobed, and differs
from all the other Ascidiidse in having no internal longitudinal bars in the branchial sac.
Further remarks upon the peculiarities and affinities of the genus will be found below the
descriptions of the two species.

ILjpobijthius calycodes, Moseley (PI. XXXVII. figs. 1-5).

Ili/pobi/thim calycodes, Moseley, Trans. Linn. Soc. Lond., ser. ii., Zool., vol. i. p. 287.

This is one of the two species described by Professor Moseley in his paper " On two
new Forms of Deep-Sea Ascidians, obtained during the Voyage of H.M.S. Challenger,"
published in December 1876. As I have been able, from an examination of the single
fragmentary specimen, to add little to Mr. Moseley's excellent account of this species, I
shall merely transcribe the most important parts of that description, and refer for further
]iai'tieulars to the original paper.

" The animal has the form of an inverted cone, compressed laterally so as to have an
oval transverse section. From the apex of the inverted cone is continued a cylindrical
stem, which is enlarged towards its inferior extremity (PI. XXXVII. fig. 1). The
test is hyaline and extremely transparent. Where it is simple it is thin and flexible, but
in certain spots it is strengthened and rendered stiff by the presence in it of rounded or
plano-convex masses or plates of denser tissue, which are tough and cartUaginous in con-
sistence, and which are disposed over the surface of the test in a nearly symmetrical
manner. These plates are extremely conspicuous when the test is held up to the light
and viewed by transmitted light, because they refract the light strongly ; and the pattern
formed by them on the test when thus viewed has a very peculiar appearance. The dis-
position of the plates on the ventral surface of the body wfil be seen from figure 1 , that
on the dorsal surface from figure 2 (PI. XXXVII. ).

" A series of globular lobes range on either lateral margin of the body, and give it
here considerable rigidity, and a ridge of highly condensed tissue runs across the body at
the upper margin of its dorsal surface. A series of flattened plates is disposed over the
inferior region of the ventral aspect of the body, whfle the superior region of the same
aspect, covering the gill sac and perforated by the inhalent aperture, is entirely devoid
of plates, very thin and flexible, and most perfectly transparent. On the dorsal aspect of
the body a very large plate occupies the middle line inferiorly, whilst immediately above

RETORT ON THE TUNICATA. 229

it two pairs of oblong plates (PI. XXXVII. fig. 2, t.t.) form a stiff shield for the principal
viscera, which lie upon them. Two series of oval plates range on either side of the larger
median ones, and extend up as far as the exhalent aperture. The test tunic is continual
downwards from the upper region of the body to form the outer wall of the cylindrical
stem, thus forming a tube. The lower end of this tube is widened out into a funnel-
shaped mouth, and in the specimen had apparently been torn away from some object of
attachment.

"The substance of the test is composed of transparent hyaline tissue, in which are
embedded small bodies, the larger of which have a length of from *007 to '014 mm.
They are irregular in form, sometimes crystalline, or with apparently crystalHne contents.
They are not sensibly altered in appearance by the action of acetic acid, and no efferves-
cence is produced in the test tissue by that re-agent. The bodies are present in the
greatest abundance in the test-tissue at the base of the stem. In the plates of denser
tissue they are rather less abundant than elsewhere. The test forms a simple sac,
continuous with the tubular cavity of the stem.

" The exhalent orifice is an aperture in the test, situate at the end of a short tube
projecting externally on the dorsal aspect just below the nerve ganglion. Into it the
ducts of the generative glands and the rectum open. The inhalent aperture was entirely
obliterated in the only specimen obtained ; it must have lain on the ventral aspect of the
body, since the dorsal wall was intact. The arrangement of the muscular fibres and
remnants of attachment of the gill sac seemed to indicate the position for it given in the
figure, where it is introduced conjecturally (PI. XXXVII. fig. 1, br.).

" Closely attached to the inner surface of the test-wall is a delicate tunic (the mantle)
containing muscles. The muscles occur in the form of very fine bands, which have a
nearly parallel course. The series of bands springing from near the region occupied by
the heart, follow the curved inner surface of the test-cavity towards its superior margins.
The muscles are disposed most thickly in the lateral regions. The mesial region of the
dorsal surface is entirely devoid of them, but they extend over the whole ventral wall.
Only the lateral fibres are indicated in the figure ; they are prolonged superiorly in a
horizontal direction along the upper margin of the dorsal wall of the test-cavity. The
tubular cavity of the stem is filled by a core composed of muscular fibres embedded in
gelatinous tissue, a prolongation of the mantle.

" Of the gill sac only a small portion remained intact in situ, but fragments here and
there attached indicated an arrangement as shown in the figure. The small portion
in situ lay over the nerve ganglion. The fenestrations in the membrane are small, simple,
and irregular (PI. XXXVII. fig. 4).

"The mouth is situate nearly in the middle line (fig 1, ce.a.). It leads by a short
transparent oesophagus to a stomach (st.), which has opaque walls corrugated externally ;
and this viscus leads into a rectum which curves up to end at the exhalent aperture.

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

" Beneath the stomach is a tubular heart with a wide vessel leading from it downwards
towards the stem (PI. XXXVII. fig. 1, /;,).

" In the loop formed by the cesojihagus, stomach, and rectum is the large ovisac or ovary,
which is circular in outline. The elongate tubular testis running parallel to the rectum in
the middle line terminates posteriorly internally to the ovisac, its lower end spreading out
into a series of ramifications, which appear very like large nerve fibres. The testis-tube
opens into the exhalent aperture close to the rectum, as does also the oviduct, wrhich lies
to the dorsal side of the testis-tube and in the same line with it.

" The ovisac wras full of very large ova,measuring as much as 1'5 millimetres in diameter.
These ova, on slight pressure being applied, were discharged from the oviduct. They
were found to consist of a very thick transparent test, with contents composed of oily
yelk-globules, without a germinal vesicle.

" The testis was tumid, and full of an opacpue wdnte matter, which was discharged on
pressure in tenacious threads composed of spermatozoa.

" The spermatozoa are very small. They were examined under a Hartnack No. 10
(immersion system). They consist of an elongate rod-like head, measuring -005 milli-
metres in length, and an excessively fine tail, the length of which could not be determined.
All the spermatozoa examined had a small transparent vesicle attached to one side of their
heads, as shown in the figures (PI. XXXVII. fig. 5)."

The above comprises almost the whole of Professor Moseley's description of this
remarkable form, and I have only a few remarks to add. Mr. Moseley supposed that it
was allied to Boltenia. The peduncle, however, is deceptive, and does not indicate any
relationship to the Bolteninae. The whole organisation, and especially the structure of
the branchial sac, taken along with the fact that, as far as is known, reproduction is not
performed by gemmation, shows that Hypobythius must be referred to the Ascidiidae,
among which we have already a new deep-sea pedunculated genus, Corynascidia.

The body form in Hypobythius calycodes is vase-shaped, with a moderately long
peduncle attached to the narrow posterior end, whde the anterior end is broad and
truncated. The atrial aperture is placed on the dorsal edge near the anterior end, while
the branchial aperture is indistinguishable, and must have been on the torn anterior end,
but probably of much smaller size than is represented by Mr. Moseley in his restoration
(PI. XXXVII. fig. 1).

The test is cartilaginous and thin, except in certain localities, where denser carti-
laginous thickenings or nodules are developed symmetrically, as seen in Plate XXXVII.
figures 1 and 2. They are especially developed along the dorsal edge, outside the
viscera, and it wdl be seen that in this locality in Hypobythius moseleyi also the test is
somewdiat strengthened.

The mantle is thin and membranous, and has a feeble but distinct musculature.
The muscle bands are very fine but numerous. They run longitudinally, and are chiefly

REPORT ON THE TUNICATA. 231

on the sides, the dorsal edge being entirely free from them, as in Hypobyihius moseleyi.
In some places on the sides they are placed very closely, and have a curiously undulating
course (PI. XX XVII. fig. 3).

The longitudinal arrangement of the chief bands of the musculature recalls the twelve
or fourteen parallel and longitudinally running muscle bands in the allied genus Ciona,
and also the usually longitudinal arrangement of the musculature in the Ckvelinidae.

The branchial sac is the most remarkable characteristic of Hi/pobyt/iius, and distin-
guishes it from all other Simple Ascidians. There are no folds, and there are no internal
longitudinal bars, a condition which is only equalled in simplicity by the sac in the genus
Clavelina. Only a single system of vessels can be recognised, branching and anastomosing
so as to form a close network (PI. XXXVII. fig. 4), the small rounded meshes of which
are the stigmata. The tentacles and dorsal lamina cannot be made out.

The viscera form an elongated compact mass along the dorsal edge of the branchial
sac (PL XXXVII. fig. 1). The alimentary canal is simple, forming a U shaped loop open
anteriorly. This seems at first sight an abnormal arrangement, but if the intestine
(fig. 1, r.) be pulled more to the left and ventrally (towards the right hand side of the
figure), so as to lie upon the left side of the branchial sac, the relations of the parts of the
alimentary canal will be found to be much the same as those in Ascidia, or any other
typical Simple Ascidian.

The globular ovary and the ramified testis lie together in the intestinal loop, between
the stomach and the intestine, and the oviduct and large vas deferens (called by Moseley
the tubular testis) run anteriorly alongside the rectum, and on its right hand side, which,
if the intestine be pulled ventrally, as suggested above, would become the dorsal side, the
normal position of the genital ducts in the Ascidiidae.

One specimen, somewhat damaged, was obtained by the trawl in the North Pacific Ocean,
at Station 248 ; July 5, 1875 ; lat, 37° 41' N., long. 177° 4' W.; depth, 2900 fathoms;
bottom temperature, 1°"1 O; bottom, red clay, with concretions of peroxide of manganese.

Hypobyihius moseleyi, n. sp. (PI. XXXVII. figs. 6-9).

External Appearance. — The body is of an elongated pyriform shape, compressed
laterally, and attached by the posterior end. The anterior end is broad and slightly
rounded ; the posterior is narrow, produced, and tapers to the small terminal area of attach-
ment. The dorsal and ventral edges are long, and converge posteriorly from the end of the
wide anterior extremity. The apertures are both anterior, large, and open, but sessile, and
apparently not lobed ; the branchial is near the ventral edge of the anterior end, and is
directed anteriorly; the atrial is at the anterior extremity of the dorsal edge, and is
directed anteriorly and slightly dorsally.

The surface is smooth all over. The colour is yellowish-grey, pale brown in parts.

Length of the body, 9 cm.; breadth of the body, 4 cm.

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

The Test is cartilaginous, but thin and almost membranous; it is slightly thickened
alung; the dorsal edge ; it is soft and easily torn, and is semi-transparent.

The Mantle is thin a. id membranous ; it adheres closely to the inner surface of the test.
The musculature is feeble ; the bands are light brown in colour, but are narrow and distant.

Tlie Branchial Sac is not folded ; it is thin, but of moderate strength on account of the
small size of the stigmata. The vessels form a close irregular network. The stigmata are
small and circular, or polygonal, and have no definite arrangement,

The Endostyle is narrow. It is not prominent, but distinct, and extends down to the
ventral edge of the narrow posterior end of the sac, and then turns and ascends the dorsal
edge, as far as the oesophageal aperture, which is situated about half-way up the sac.

The Dorsal Lamina is a very narrow plain membrane, with no folds nor thickenings.

The Dorsal Tubercle is elongated antero-posteriorly ; it is placed near the atrial
aperture ; the right horn is large, and is curved outwards to the right.

The Nerve Ganglion is small, oval, and placed a little way posterior to the dorsal
tubercle ; it has the rounded neural gland rather on its right side.

The Viscera. — The intestine and genitalia form an elongated compact mass along the
dorsal edge of the branchial sac.

This interesting specimen was in such bad condition that at first sight it seemed like a
confused mass of lacerated and entangled membranes. It has evidently been torn from
end to end along the right side, and part of the mantle and branchial sac are entirely
gone, while what remains is in parts displaced and hanging in shreds. Consequently it
has been impossible to give the external form with precision, and no trace of the tentacles
has been discovered.

The external shape is more or less pyriform, with the anterior end wide and the
posterior narrow, and produced to form a short peduncle (PI. XXXVII. fig. 6). The
apertures are placed at the extremities of the anterior end, and are large circular holes
apparently not lobed. The test is thin and soft, It is slightly thickened along the
dorsal edge, forming a pad over the viscera corresponding to the plates (fig. 2, t.t.) in
the last species, but no cartilaginous nodules are present, It is not modified in any way
on the peduncle.

The mantle has a few narrow light brown muscular bands running chiefly longitudi-
nally along the middle of each side. There are none down the dorsal and ventral edges.
They are not crumpled as in the mantle of the last species (compare figs. 3 and 9 on
PL XXXVII.) , and the arrangement is very suggestive of the musculature of some of the
Clavelinidae.

The branchial sac (PL XXXVII. fig. 7) is veiy simple, being formed by a network of
vessels, all similar, and having no symmetrical arrangement. There are no folds, and no
internal longitudinal bars.

REPORT ON THE TUNICATA. 233

The dorsal lamina is a simple narrow membrane, projecting from the dorsal line of the
branchial sac, and having its surface in direct continuity with that of the neighbouring
vessels (PI. XXXVII. fig. 7, d.l).

The dorsal tubercle is rather large (PL XX.W'II. fig. H, d.t.) ami lias the right horn
curved outwards, while the left is rudimentary. The posterior end is rounded, and the
anterior aperture is almost obliterated. The nerve ganglion is roundish or subtriangular,
and gives off numerous nerve trunks (PL XXXVII. fig. 8, n.g.). The neural gland
(n. (jl.) is large and ovate, and lies to the right side of the ganglion. It is connect ed
with the dorsal tubercle by a distinct duct.

The viscera form an elongated mass on the dorsal edge of the branchial sac, below the
thickened part of the test, and are arranged very much as in Hypobythius calycodes.

The single fragmentary specimen of Hypobythius moselcyi was obtained in the South
Atlantic, off the coast of Buenos Ayres, at Station 320; February 14, 1876 ; lat. 37° 17' S.,
long. 53° 52' W. ; depth, 600 fathoms ; bottom temperature, 2°7 C. ; bottom, hard ground.

Ciona, Fleming.

Ascidia, Linnaeus, Sys. Nat., 12th Edit. 1766. In part.

Ascidia, 0. F. MiiUer, Zool. Dan., vol. ii. 1780. In part.

Phallusia, Savigny, Mem. Anim. sans Vert. Pt. ii. fasc. 1. 1816. In part.

Ciona, Fleming, British Animals. 1828.

Ascidia, Forbes and Hanley, British Mollusca, vol. i. 1853. In part.

Ciona, Hancock, On the larval state of Molgula, &c, Ann. Mag. Nat. Hist, ser. iv. vol. vi.

1870.
Ciona, Heller, Untersuch. ii. d. Tun. d. adriat. Meeres, Abth. ii. 1875.
Ciona, Kupifer, Jahresber. d. Commiss. 187"'.
Ciona, Traustcdt, Oversigt over de fra Danmark, &c, Ascidiae Simplices, Kj0benhavn. 1880.

Body sessile, attached ; branchial aperture eightdobed, atrial sixdobed.

Test gelatinous or cartilaginous, but soft.

Mantle with the musculature chiefly in the form of a small number of distinct

longitudinally running bands.
Branchial Sac not plicated; internal longitudinal bars papillated ; stigmata

straight.
Dorsal Lam in" in the form of languets.
Tentacles simple.
Intestine lying on the left side of the body, and extending beyond the branchial

sac posteriorly.

Savigny, in his " Memoires," divided the genus Phallusia into three tribes: —
the Phallusia! Pireme, the Phallusiae Simplices, and the Phallusia? Cionas; the last of which
he characterised as having the branchial sac shorter than the mantle and the viscera

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

extending beyond the branchial sac posteriorly. In this section he placed the two species
Ascidia intestinalis, Linmeus, and Ascidia canina, 0. F. Midler.

In 18 28, •Flerning(" British Animals," p. 468), adopting Savigny's term, founded the genus
Oiona, for the common British species Ciona intestinalis. For a considerable time, how-
ever, this name was not received, and we find in Forbes and Hanley's " British Mollusca"
(1853), the two species intestinalis and canina still retained in the genus Ascidia.

Things remained in this condition till 1870, when Hancock (Ann. and Mag. of Nat.
Hist., ser. iv., vol. vi.) revived Ciona as a generic name, gave it a full and satisfactory
definition, and added a new species, Ciona fascicidaris. The name has since been used
by Kupffer, Heller, and Traustedt, and may now be considered as firmly established.

The body in Ciona is always sessfle and attached, and is usually elongated antero-
posteriorly. The test is soft and almost gelatinous, being flaccid and transparent when
living. The musculature of the mantle is equally developed upon both sides of the body,
and is rather characteristic. A few strongly marked bundles — twelve to fourteen in Ciona
intestinalis — are found running longitudinally from the bases of the siphons at the anterior
end to the opposite extremity of the body. The other muscle bands, which are transverse
and obhcpie, are very much weaker and more irregularly arranged. On account of the
strength of the longitudinal bands, and the softness of the test, the body has very great
powers of contraction.

The branchial sac is neither folded nor plicated when living and expanded, but usually
when a specimen, which has been put into alcohol living, and has contracted its whole
body forcibly, is examined, the branchial sac is found to be crumpled and corrugated, so
as to give very much the appearance of " minute plication." This is merely caused, how-
ever, by the pressure of the surrounding mantle, and when that has been removed the
sac may be spread out so as to assume more the look of its natural structure.

The most characteristic features of Ciona are the dorsal lamina, which is in the form
of languets, like those of Corella, and the alimentary and genital viscera, which are situated
upon the left side of the branchial sac, as in Ascidia, but extend beyond it posteriorly, so
as to form a rudimentary abdomen. In this last character Ciona differs from both
Corella and Ascidia, and shows affinity with Ecteinascidia and some of the other
Clavelinidae.

This genus contains only a small number of species. In addition to Ciona cam mi,
0. F. Midler, Ciona intestinalis, Linnpeus, and Ciona. fascicularis, Hancock, which
have been mentioned above, there remain the Ascidia corrugata of the " Zoologia Danica,"
which is probably either Ciona canina or Ciona intestinalis, Alder's1 Ascidia .pulchella,
which may possibly be merely a variety of Ciona intestinalis, and Verrill's2 Ciona

1 Observations on British Tunicata, Ann. and Mag. Nat. Hist. ser. iii., vol. xi., 1863.

2 Description of some imperfectly known and new AscidianB from New England, Amer. Jourii. of Sci. and Arts,
ser. iii., vol. i., No. 2, 1871.

UK PORT ON Till: Tl NK 'ATA. 235

tenella, which is also closely allied to Ciona in/rsfiualis. Finally, the Challenger expe-
dition has discovered two new species, which 1 have dedicated to the founders of the
genus, Savigny and Fleming.

Ciona flemingi, Herdman (PI. XXXIV. figs. 7-10).

Ciona flemingi, Herdman, Prelim. Rep., Proc. Eoy. Soc. Edin., 1879-80, p. 4G1.

External Appearance. — The body is somewhat pyriform and elongated; the anterior
end is wide, and the posterior much narrower, forming a short stalk turned vent rally, and
attached to some foreign body by the extremity of its right side. The apertures are
situated at the anterior end, and are inconspicuous; the branchial is near the ventral
edge, the atrial is near the dorsal edge; they are equally far forward, the most anterior
point of the body being placed between them.

The surface is smooth ; the colour is light grey.

Length of the body, 2 '2 cm. ; breadth of the body, 8 mm.

Tlie Test is thin, soft, and almost gelatinous ; it is transparent, the body showing
through distinctly. The vessels are few.

The Mantle is normal ; the musculature is rather feebly developed, consisting chiefly
of a few straight bundles running longitudinally.

The Branchial Sac is rather thick, small, and shrunken-looking. The transverse
vessels are all of much the same size. The internal longitudinal bars are coarse and strong ;
they are much crumpled, and bear irregular knob-like papillge at their intersections
with the transverse vessels ; no intermediate papillae are present. The meshes have their
greatest extent longitudinal, and contain each two to three elongate-elliptical stigmata.

The Dorsal Lamina is reduced to a series of languets. Each is short ami stout, and
has a hook or tusk-like form.

TJtc Tentacles are simple, all of one length, and twelve in number.

TJie Dorsal Tubercle is cordate, small, and has both horns turned inwards.

TJie Viscera extend beyond the branchial sac posteriorly.

This little species seems to be distinct from the i'rw species hitherto referred to the
genus. The body form, the short languets, and the small number of tentacles, are
all very characteristic features. The short stalk mentioned above is very slight (PI.
XXXIV. fig. 7), and is merely the narrowed posterior end of the body. It is not suffi-
cient to affect the general statement that the body is sessile in Ciona.

The musculature of the mantle is not very strong, but takes the form of longitudinal
bands so characteristic of the genus.

The branchial sac, when first opened, showed the contracted and irregularly crumpled
condition so frequently seen in spirit specimens of Ciona intestinalis, ami caused by the
pressure of the strongly contracted mantle lying over it.

(ZOOL. CHALL. EXP. — PAET XVII. — 1882.) E 31

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

The internal longitudinal bars and the papillae are very strong and coarse, and the
former are placed pretty close together (PI. XXXIV. fig. 8), so as to bound long narrow
meshes, each usually containing two stigmata only.

The languets along the dorsal line of the sac are very short, and are curved so as to
have a hooked shape (PL XXXIV. fig. 9). The tentacles are very few, and are all of one size.

The dorsal tubercle (PL XXXIV. fig. 1 0) is simple, and is very similar to that of
Ciona intestinalis.

One specimen of this species was dredged off Gomera, Canary Islands, February 10,
1873, in 78 fathoms.

Ciona savignyi, n. sp. (PL XXXV. figs. 1 and 2).

External Appearance. — The shape is probably oblong and nearly cylindrical, like that
of Ciona intestinalis; the posterior end of the body is rounded and broad. The dorsal
and ventral edges are nearly straight, tapering somewhat anteriorly. The body is
attached by the left side at what would probably be one-third of the way forwards from
the posterior end in the fully expanded condition. The apertures are rather close,
terminal, and inconspicuous through contraction.

The surface is smooth, except at the posterior end of the left side and the ventral edge.
The colour is whitish grey, hyaline where the test is thin.

Length of the body, 1*3 cm.; when expanded, probably 2 to 2 "5 cm. ; breadth of the
body, 1*2 cm.

T/ie Test is moderately thick and strong, but is transparent. Vessels are present, but
not conspicuous.

The Mantle is thin, but strong ; and the musculature is well developed. A few strong-
longitudinal bands of fibres run down nearly the whole length of the body to the posterior
end, and are crossed by closer, but weaker, chiefly transverse, fibres, which are not arranged
in broad bands.

The Branchial Sac is rather strong, and is not plicated. The alternate transverse
vessels are wider than the intermediate ones. The internal longitudinal bars are narrow,
and bear large paddle-shaped papillae at the angles of the meshes, and no intermediate
ones. The meshes are rather larger transversely than longitudinally, and contain each
about five rather large stigmata ; each mesh is generally divided transversely by a narrow
horizontal membrane connecting the internal longitudinal bars, but not interrupting the
stigmata.

The Endostyle is conspicuous, undulating, and opaque white.

The Dorsal Lamina is formed by a series of rather large and close-set languets.

The Tentacles are filiform, and are rather long and numerous.

The Viscera extend posteriorly for a short distance beyond the branchial sac, and
form the posterior end of the body.

REPORT ON THE TUNICATA. 237

The single specimen of this Ciona is contracted into an almost square bod)- ; the
whole anterior end, to the extent of probably nearly half the total length, is retracted,
and the test forms a raised pad all round the slightly sunken ana in which the apertures
are found (PL XXXV. fig. 1). A similar condition is often produced in Ciona. intestindlis
by sudden immersion of the living animal in alcohol.

The specimen is attached to a fragment of some kind of fibrous plant by the left Bide
of the body, nearly two-thirds of the distance from the posterior to the anterior end, or
at what would in the expanded condition be about one-third of the way up. The posterior
end is free and rounded, and is pretty broad ; the anterior end, judging from the distance
between the apertures, must have been narrow.

The test is strong, but transparent, the wide intestine showing through distinctly
at the posterior end of the left side ; along the dorsal edge of the right side it is consider-
ably roughened, rising here and there into slight tufts and processes.

The mantle is muscular, and resembles that of Ciona vntestinalis more than Ciona
flemingi. The longitudinal bands are well-marked, and are often double.

In the branchial sac the papillae are very large and expanded, being of the wide paddle
shape found in several species of Ascidia. The stigmata are large, and consideraMy
wider than the fine longitudinal interstigmatic vessels ; they frequently break through the
slighter transverse vessels, and extend from one larger vessel to the next (PL XXX V.
fig. 2). Wide horizontal membranes extend from papilla to papilla, along the transverse
vessels, and narrower ones are often present, dividing the meshes transversely between the
papillae, but not interrupting the stigmata.

The languets are large, and form a conspicuous fringe along the dorsal edge of the
branchial sac. The endostyle is white and conspicuous, and the tentacles are long.

On account of the great state of contraction of the anterior end of the specimen, and
especially of the siphons, I was unable to make out satisfactorily the condition of the
dorsal tubercle. To the naked eye it seemed small and compact, and is probably simply
rounded or cordate, like the tubercles of Ciona intestincdis and Ciona flemingi.

One specimen of Ciona savignyi was dredged off Kobd, Japan, at Stat inn 233a ; May
17 to 19, 1875 ; lat. 34° 35' N., long. 135° 10' E. ; depth, 8 fathoms and 50 fathom- ;
bottom, mud and sand.

Family Clavelinid^e.

Body fixed, posterior end usually prolonged into a short stalk, which may give off
creeping stolons ; never coated with sand grains.

Test gelatinous, rarely cartilaginous. Apertures usually not lobed, or only indis-
tinctly so.

Branchial Sac not folded ; internal longitudinal bars usually absent, when present
they are not papillated ; stigmata straight.

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

Tentacles simple, filiform.

Intestine always extending beyond the branchial sac posteriorly.
Genitalia placed in the intestinal loop. Reproduction by gemmation is also usual,
and results in the formation of colonies.

For a detailed account of my reasons for considering the Clavelinidse as Simple
Ascidians, I must refer to the second part of the Preliminary Report.1 It will be
sufficient here to mention that in organisation the Clavelinida? are most closely allied to the
Ascidiidse ; that if we consider only the structure of a single individual, an Ecteinascidia
might be placed in the same genus wTith a Ciona, and that the property of reproducing by
gemmation and forming colonies is really the only essential character which separates the
Clavelinidse from the Ascidiidse ; and finally, that this property of budding cannot
be considered as forming a strict line of demarcation, since all the apparatus necessary for
the process is present in a more or less developed condition in other Simple Ascidians, and
has been observed in species of Ascidia 2 and Ciona3 to produce stolons similar to those
of a Clavelina. On account of their property of reproducing by gemmation the Claveliuidaj
must be considered as having a closer affinity to the Compound Ascidians than have any
others of the Simple Ascidians. They form a passage between such forms as Ciona in the
Ascidiidse and Diazona in the Compound Ascidians.

The Challenger genus Ecteinascidia is an interesting connecting bnk between t he-
other Clavelinidse and the Ascidiidse. It forms colonies by gemmation, and therefore
belongs to the Clavelinidse, but in the rest of its characters it more closely approaches
Ciona than Clavelina.

The curious form which Philippi described in 1843, under the name of Rh o pal 'cea, must
for the present remain unplaced as to family. It was described as a Simple Ascidian,4
but the account given of it and the figures published certainly suggest that it belongs
to the Clavelinidse, and will probably find a place near Ecteinascidia. In opposition to
this view, the internal longitudinal bars of Rhopal&a are figured as being distinctly
papillated, a condition of things of which I have never seen a trace in any specimen of
Ecteinascidia. For a determination of the affinities of this interesting species we must
be content to wTait till we have some information as to the important point of whether it
possesses the property of reproducing by gemmation.

Setting Rhopalaa aside, there remain three genera which undoubtedly belong to this
family, viz. : — Clavelina, Ecteinascidia, and Perophora, each of which is represented by
several species. The three genera are very distinct, and are easily separated from one

1 Proc. Roy. Soc. Ediu., 1879-80, p. 714.

" I have found specimens of Ascidia aspersa, 0. F. Muller, with long stolon-like processes extending from the test
at the posterior end and left side of the body.

3 e.g., frequently in large individuals of Ciona intestinalis, Linnaeus.

4 This was subsequent to the publication of Milne-Edwards' Memoir creating the group of Social Ascidians.

EEPOET ON THE TUNICATA. 239

another. Clavelina and Ecteinascidia, though differing so decidedly in the structure of
the branchial sac, are rather more closely allied than is either of them to Perophora, which
agrees, however, with Clavelina in the absence of internal longitudinal bars. In the
shape of the branchial sac, and its relations to the viscera, Peropltom may be compaivi]
to Ascidia, while Ecteinascidia and Clavelina represent dona amongst the Ascidiidae ;
even in Perophora, however, the intestine sometimes extends slightly beyond tin- branchial
sac posteriorly.

These three genera may be distinguished briefly thus : —

Clavelinidj:.

Branchial sac having internal Branchial sac having no internal

longitudinal hars. longitudinal bars.

Ecteinascidia

Intestine extending beyond Intestine at side of bran-

the branchial sac, so as to chial sac; no abdomen,

form an abdomen.

Clavelina. Perophora.

The Challenger collection contains two species of Clavelina, and three other forms
which necessitated the formation of the genus Ecteinascidia. Perophora is not
represented.

Ecteinascidia, Herdman.

Ecteinascidia, Herdman, Prelim. Rep., Proc. Eoy Soc Edin., 1879-80, p. 722.

Body oblong, usually tapering posteriorly. Apertures indistinctly lobed.

Test cartilaginous or membranous.

Mantle thin, musculature moderately strong.

Branchial Sac having internal longitudinal bars, but no papillae; stigmata

straight.
Dorsal Lamina in the form of languets.

Tentacles simple.

Viscera extending beyond the branchial sac posteriori}".

This genus was formed for the reception of three new species of colony-forming
Simple Ascidians, with non-papillated internal longitudinal bars in their branchial sacs.
This character distinguishes them from both Perophora and Clavelina, and necessitated
the formation of a new genus.

240

THE VOYAGE OF H.M.S. CHALLENGER.

Ecteinascidia has its nearest ally in Clavelina, and is intermediate in its characters
betweep that genus and Ciona, thus leading towards the Ascidiidas. The three species
differ considerably in external appearance, and are also easily distinguished by the structure
of their branchial sac and other internal organs.

They may be separated, according to the conditions of their tests, by the following

table : —

Ecteinascidia.

Test membranous.

Ecteinascidia turbinala.

Test cartilaginous.

Test thin in the upper
part, of a dark colour.

Ecteinascidia fusca.

Test thick all over, of a
light grey colour.

Ecteinascidia crassa.

Ecteinascidia crassa, Herdman (PI. XXXVI. figs. 12-14).

Ecteinascidia crassa, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 723.

External Appearance. — The body is irregular in shape, it is rudely triangular, or rather
of a flattened pyramidal form, and is attached by an extended base to a clump of sponge
spicules. The anterior end is narrow but more or less rounded. The sides are irregular ;
the posterior end is wide and expanded. The apertures are both near or at the anterior
end, they are sessile and inconspicuous, and no lobes are visible.

The surface is rather irregular, but not rough. The colour is a warm grey, slightly
yellowish in places.

Length of the body, 1*6 cm. ; breadth of the body (at the posterior end), 1*5 cm.

Hie Test is strong, cartilaginous, and very thick.

TJie Mantle is strongly developed, and the muscle bands are thick.

The Branchial Sac has delicate but distinctly marked undulating internal longitudinal
bars, borne on large triangular connecting ducts. No papillae are present. The transverse
vessels are all of one size, and are rather wide. The stigmata are elongate-elliptical in
shape, and are very regular. The meshes are nearly square, and contain generally three
stigmata each.

The Dorsal Lamina is in the form of lanmiets.

The Viscera extend considerably beyond the branchial sac, and form a distinct
abdomen.

This is a small and rather irregular species, which differs notably in external appear-
ance from the other two species, inasmuch as its posterior end is wide, and expands into
a broad base in place of tapering to form a short stalk.

REPORT ON THE TTJNICATA. 241

A second specimen in the collection differs somewhat in its proportions from the one
figured (PI. XXXYI. fig. 12) and described above. Its dimensions arc as follows :-
length, 2 cm. ; breadth at the posterior end, 3"5 cm. Consequently, in this specimen H i
base is even broader than in the other, and exceeds the Length of the body.

The test in this species is solid, and is in one of the specimens enormously developed,
forming a large mass, in which the body of the individual is imbedded. The anteriorly
placed apertures are both sessile, and have no visible lobes.

The branchial sac is strongly contracted and rather crumpled. The stigmata are
shorter than, but similar in shape to, those of the other two species (PI. XXXYI. fig.
13). The internal longitudinal bars are very fine, and are slightly undulated; they are
attached to the summits of very large triangular flaps or connecting ducts, which 1
from the wide transverse vessels (PI. XXXYI. figs. 13 and 14).

The tentacles are simple and filiform, but I was unable, without injuring the single
specimen examined, to determine their number, and the condition of the dorsal tubercle.
These are points, however, of secondary importance, and the species is, I believe, sufficiently
characterised without them.

The alimentary and genital viscera extend in this species for a considerable distance
beyond the branchial sac, so as to form a distinct abdomen, which is almost as large as
the thorax, and is connected with it by a narrow pedicle traversed by the oesophagus, the
intestine, and the genital ducts.

Two specimens of Ecteinascidia crassa were found attached to the spicules of a large
Hexactinellid sponge, dredged off Ki Island, at Station 192 ; September 26, 1874 ; lat.
5° 42' S., long. 132° 25' E. ; depth, 129 fathoms; bottom, mud.

Ecteinascidia fusca, Herdman (PI. XXXYI. figs. 7-11).

Ecteinascidia fusca, Herdman, Prelim. Rep., Proc. Roy. Soe. Edin., 1879-80, p. 723.

External Appearance. — The individuals of this species are united into a colony by
a short thick irregular stolon. The shape of each individual is very elongated, some are
rudely club-shaped. The anterior end is wide and truncated ; the posterior half is narr< >wer,
contorted, and passes down into the stolon. The apertures are nearly terminal, both are
placed upon the right side of the extremity ; the branchial is near the middle, and the
atrial near the dorsal edge.

The surface is smooth but uneven, especially at the posterior end, where knobs and
processes are usually present. The colour is dark brown.

Length of the body, 47 cm. ; breadth of the body, 1*5 cm.

The Testis cartilaginous, stiff, opaque, and thickish, especially in the posterior part.
sometimes it is rather thin at the anterior end. Vessels are present.

The M antle is thin ; the muscular bands are distant, bul well-marked, and are of a
reddish-brown colour. The larger bundles run longitudinally.

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

The Branchial Sac is delicate. The internal longitudinal bars are narrow but distinct ;
they are undulating, and are supported by broad horizontal membranes, provided with
triangular flaps, to the apices of which the bars are attached. There are no papillse. The
transverse vessels are narrow, and all of one size. The meshes are regular, elongated
antero-posteriorly, and contain each about three long and regular stigmata, with parallel
sides and rounded ends.

TJie Dorsal Lamina is represented by a series of long narrow languets, with undula-
ting edges, and tapering to a fine point.

The Tentacles are filiform, few, and distant.

The Dorsal Tubercle is irregularly oval in outline.

Tlie Viscera are prolonged beyond the branchial sac posteriorly, and extend into the
narrow posterior part of the body.

This is a strong and moderately large species (PI. XXXVI. fig. 7). The individuals
or Ascidiozooids are united by a short rough stolon, which is merely a prolongation of
their posterior ends. On this stolon the test is very thick and strong ; while over the
anterior part of the body it is usually thinner ; in one individual the dark-brown longi-
tudinally running muscle bands of the mantle show through distinctly. The posterior
part of the body, into which the intestine is prolonged, is much narrower than the anterior
or branchial region. The apertures are both near the anterior end, and are not far apart.
They are sessile, but distinct, and are lobed, though usually only indistinctly and irre-
gularly. When most distinct, the lobes seem to be six round the atrial aperture and
seven or eight round the branchial.

The appearance of the mantle is rather characteristic, the dark reddish brown muscle
bands showing very distinctly as fine distant lines on the thin membrane.

The branchial sac (PL XXXVI. fig. 8) is rather like that of Ecteinascidia crassa ; it
differs from it chiefly in the stigmata being longer, while the transverse vessels are
relatively narrower, and in having the large triangular connecting ducts or flaps of the
horizontal membranes shorter and placed rather further apart (PI. XXXVI. figs. 8 and
13). In Ecteinascidia crassa the points of these flaps, when laid down on the sac (fig. 13),
extend past the tops of the stigmata of the next row, while in the present species they
only extend three-quarters of the way down the stigmata of their own row (fig. 8).
In consequence of the length of the stigmata, the meshes in the present species are
elongated antero-posteriorly, while in the Ecteinascidia crassa they are square (compare
figs. 8 and 13, PI. XXXVI. ). The stigmata are usually very regular, with rounded
ends. Figure 9 shows a slight irregularity which was noticed.

The languets in this species are long and narrow, tapering gradually to a point. When
stretched out, each overlaps the succeeding one by about half its length (PI. XXXVI.
fig. 11, I.). They are arranged down the centre of a wide membranous area which runs

REPORT ON THE TUNICATA. 243

along the dorsal edge of the branchial sac, and is crossed transversely by the horizontal
membranes which bear the languets. At each side of this membranous area, just where
the stigmata commence, is a row of smaller languets, exactly similar in size, shape, and
position to the triangular flaps which support the internal longitudinal liars; these two
rows, however, at the sides of the dorsal lamina, bave no bars attached to their apices
(PL XXXVI. fig. 11).

The tentacles are not numerous, and arc all of one length (PI. XXXVI. fig. 10, tn.).
They spring from a circular band of muscular fibres which forms the posterior end of the
branchial sphincter.

The dorsal tubercle is ovate in outline, and lies in a shallow peritubercular area, out
of which it projects fully half way across the praebranchial zone to the base of the
tentacles (PL XXXVI. fig. 10, d.t.). The neural gland and the ganglion form a
rounded opaque mass, situated immediately posteriorly to the dorsal tubercle.

One colony of Ecteinascidia fusca, formed of several individuals, was obtained at
Banda, Moluccas ; depth, 17 fathoms.

Ecteinascidia turbinata, Herdman (PL XXXVI. figs. 1-0).

Ecteinascidia turbinata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1879-80, p. 721.

External Appearance. — In this species many individuals are united into a colony by
delicate, much-branched, but short stolons. The shape of each individual is elongated,
and sometimes almost pyriform. The anterior three-fourths is nearly cylindrical, while
the posterior part tapers rapidly to a short slender stalk, continuous with the stolon. The
anterior end is broad, truncated or rounded. The apertures are sessile and minute, they
are both at the right side of the anterior end, and are not lobed.

The surface is smooth. The colour is a light yellowish-brown.

Length of the body, 3 cm.; breadth of the body (near the anterior end) 1 cm.

TJie Test is thin and membranous ; it is transparent.

The Mantle is thin.

The Branchial Sac is simple. The internal longitudinal bars are narrow, but well
marked, they are borne on stout connecting ducts ; there are no papillae. The transv
vessels are all of one size, and are very wide ; no horizontal membranes are present. The
meshes are greatly elongated antero-posteriorly, and contain each two or three long narrow
stigmata.

The Dorsal Lamina is represented by a series of tentacular languets.

The Tentacles are simple and filiform, and are of three lengths placed alternately ; there
are about twenty of the long and twenty of the medium size, and forty of the short ones.

The Dorsal Tubercle is elongated, and tapers posteriorly. The aperture is anterior, and
the horns are coiled.

The Viscera extend slightly beyond the branchial sac posteriorly.

(3DOL. CHALX. EXP. — r.YRT XVII. — 1S82.) R 32

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

This is a very elegant species, and differs from the two other species of Ecteinascidia
externally in its more definite shape and the delicacy of its test. The individuals are
united by their narrow posterior ends to a delicate, much-branched stolon (PL XXXVI.
fig. 2). They are attached to this stolon at short intervals, and consequently are crowded
pretty closely together, forming large colonies (PL XXXVI. fig. 1). Buds of various
sizes are also found here and there attached to the stolons (fig. 2). The shape of
the individuals or ascidiozooids varies from cylindrical to conical, the anterior end being
broad and rounded, while the posterior is narrow. The test is very thin and quite trans-
parent, allowing the viscera to be seen through distinctly.

The branchial sac is rather different from those of Ecteinascidia crassa and Ectein-
ascidia fusca. The transverse vessels are extremely wide, and have no horizontal mem-
branes attached to them (PI. XXXVI. fig. 3). The internal longitudinal bars are narrow,
and are borne on strong but short connecting ducts, which widen out as they approach
the bar, and are narrow where they join the transverse vessels. They are very different
from the wide triangular flaps found in Ecteinascidia crassa and Ecteinascidia fusca.
The meshes are much elongated antero-posteriorly, and the stigmata are narrower in
comparison to the interstigmatic vessels than in the other two species of Ecteinascidia.

The languets (PL XXXVI. fig. 6. 1.) are of moderate length, are rather distantly placed
(about their own length apart), and are tentacular in shape, in place of being triangular
and flattened antero-posteriorly as usual. The membranous area on which they are
placed is much narrower than in EcteinaSi idia fusca, but has a band of muscular fibres
running down its centre (fig. 6).

For a short distance on each side of this dorsal membranous area there is no internal
longitudinal bar, although short papillae are seen projecting from the transverse vessels in
a longitudinal row on each side, and evidently representing the connecting ducts
(PL XXXVI. fig. 6, c.d.).

The tentacles are very dissimilar, the longest ones being about seven times as long as
the shortest. The intermediate ones are scarcely half the length of the longest ones.
Calling them A, B, and C, they are found to be arranged alternately thus : — A, C, B, C, A,
&c. (PL XXXVI. fig. 4, tn., tn.' and tn."). The elongated dorsal tubercle tapers from the
anteriorly placed aperture so as to become carrot-shaped.

On account of the length of the branchial sac, the alimentary and genital viscera only
extend slightly beyond its posterior end. The stomach is small, and forms the posterior
end of the visceral mass. The intestine after leaving it runs for a short distance
anteriorly, and then slopes across the left side of the posterior part of the branchial sac
from the ventral to the dorsal edge, along which it is continued anteriorly, as the con-
spicuous dark-coloured rectum, towards the anteriorly placed atrial aperture (PL XXXVI.
figs. 1 and 2).

The genital glands occupy the intestinal loop ; the ovary is placed alongside, and

REPORT ON THE TUNICATA. 245

curved parallel with the intestine, and the testis is in the concavity of the ovary (PI.
XXX\ I. fig. r>). The vas deferens has a remarkable course. It arises from the side of
the testis opposite to the ovary and intestine, and runs for a short distance away from
these organs towards the dorsal edge. It then turns anteriorly, and converges towards
the rectum, which it crosses close to the anus (fig. 5, v. J.).

In the Liverpool Free Public Museum there are several colonies of Ecteinascidia tur-
binata, from Alexandria Harbour ; 3 to 5 fathoms.

The Challenger expedition obtained one large colony, of about twenty adult indi-
viduals and some buds, at Bermuda, in .shallow water.

Clavelina, Savigny.
Ascidia, 0. F. Miiller, Zoologia Danica, vol ii. 1780. In part.
Ascidia, Cuvier, Mem. du Mus., t. ii. 1815. In part.
Clavelina, Savigny, Memoires sur les Aniniaux sans Vertfebres, linl partie, 1st fasc, p. 87 ; ami

Tableau Systematique, p. 171. 1816.
Clavelina, Milne-Edwards, Observations sur lea Ascidies Couiposees des cotes de la Mauclie.

Mem. Inst. France, t. xviii. 181:}.
Clavelina, Giard, Recherches sur les Synascidies, Arch. Zool. exper. et geiu'r., t. i. 1S7_'.

Body oblong, more or less stalked.

Test gelatinous or cartilaginous. Apertures circular, not lobed.

Mantle thin.

Branchial Sac with no internal lonp-itudinal bars: stigmata straight.

Dorsal Lamina in the form of languets.

Tentacles simple.

Viscera extending beyond the branchial sac posteriorly.

In 1816, Savigny founded this genus for the reception of two species, which had
previously been classed under Ascidia, viz.: — Ascidia borealis, Savigny ( = Ascidia clavata,
Pallas), and Ascidia lepadiformis, Muller. He characterised the genus in his
" Memoires" as including pedunculated Simple Ascidians with a gelatinous test. In the
"Tableau Systematique " (p. 171), he gives a full diagnosis, which might almost stand
unmodified as the definition of the genus as used at the present day. It is as follows : —

" Corps pedicure par- la base, a enveloppe gelal incuse ou cartilagineuse.

" Orifice branchial depourvu de rayons ; Tanal de meme.

"Sac bra nchiat 'non plisse, tres-court, et n'arrivaht pasau milieu de la tunique, surmonte'
de filets tentaculaires simples; les mailles du tissu respiratoixe depourvues de papi

"Abdomen totalement inferieur. Foie nul ou peu distinct des parois de L'intestin.
Point de c6te s'etendant du pylore a la m is.

" Ovaire unique, compris dans l'abdomen."

Savigny seems not to have known of the power of budding possessed by the Clave-
linidae, and as far as the genus Clavelina was concerned, Milne-Edwards was the first, in

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

hisgreal work on the Compound Ascidians, to show that they reproduced by gemmation,
all bough Long before Lister ' had pointed out the same fact in another genus of the famdy,
/', rophora.

Milne-Edwards gave a very full account of the anatomy and physiology of Clavelina,
and described several species at considerable length. He proposed that Clavelina and
Perophora should be separated from the Simple Ascidians, with which up till that time
(1842) they had been associated, and he formed for their reception a group, the Ascidire
Sociales, intermediate between Simple and Compound Ascidians, and independent of
both.

Griard, in his "Beehercb.es sur les Synascidies," published in 1872, adds little or
nothing to Milne-Edwards's account of the genus Clavelina, which he places along
with Perophora and the Compound Ascidians, in his Synascidiae.

Clavelina, is the typical genus of the Clavelinida?, and shows most of the characteristic
features of the family in a marked degree. It differs from Perophora chiefly in the
relation of the intestine to the branchial sac, and in having a more or less well developed
abdomen. From Ecteinascidia it is separated by the total absence of internal longitudinal
liars in the branchial sac.

The two new species of Clavelina discovered during the Challenger expedition differ
somewhat from the previously known species of the genus in the external appearance of
the colony, as in both cases the individuals are crowTded together, and the stolons are
present merely in the form of a thick mass of test substance continuous with and
uniting the posterior ends of the individuals.

Clavelina oblonga, Herdman (PL XXXV. figs. 6-10).

Clavelina oblonga, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1579-80, p. 724.

External Appearance. — The individuals are closely united into a colony by their
posterior ends, which form a thick irregular stolon. The shape of each ascidiozooid
is irregularly oblong, sometimes club-shaped or more irregular. The anterior end is wide
and rounded ; the posterior is generally very narrow. The apertures are sessile, not
lobed, and are placed both at the anterior end.

The surface is smooth, with occasional transverse wrinkles, especially towards the
posterior end. The colour is light yellowish-grey, nearly white.

Length of the body of a single individual, 2 cm. ; breadth of same, 0'6 cm. ; height
of the colony, 6 cm.

The Test is thin, especially at the anterior end ; it is transparent.

The Mantle is moderately strong. The margins of the apertures are much pigmented,
but not so as to form definite ocelli.

1 Philosophical Transactions for 1834. Part II.

REPORT ON THE TUNICATA. 247

The Branchial Sac is simple. The transverse vessels are all of one width ; they bear
horizontal membranes. No internal longitudinal bars are present. The stigmata are
short, and elongate-elliptical in shape. The interstigmatic vessels are strong.

The Dorsal Lamina is reduced to a series of languets. These are short, conical, and
tentacular, and are separated by about their own length. Tiny spring from a narrow
membranous band.

The Tentacles are short and stout ; the}- are about twenty in minilier, placed long and
short alternately.

The Dorsal Tubercle is small and irregularly oval in outline; the horns project
laterally at the anterior end.

This species forms a very elegant-looking colony of an elongated shape (PL XXXV.
fig. G). The posterior ends of the individuals are in close contact, and sink into a
common base or stolon, which forms the axis of the colony. The bodies of the separate
individuals are more or less club-shaped on account of the anterior end being much wider
than the posterior.

The test is of a soft cartilaginous consistency, intermediate between the thin
gelatinous test of Clavelina lepadiformis, and the thick cartilaginous one of Clavelina
c ) tor mis.

The branchial sac, though simple, is not delicate (PI. XXXV. fig. 7) ; the interstigmatic
fine vessels are strong, and nearly as broad as the stigmata. The transverse vessels are
moderately wide, and bear plain, not very wide horizontal membranes, which when
laid out flat scarcely cover even the tops of the stigmata immediately below them. The
ciliated stigmatic cells are short and rounded (PI. XXXV. fig. 9, sg.c).

The languets are short and stout, and are placed on a narrow membranous hand
extending- alone the dorsal edge of the branchial sac. Their liases are continuous with the
horizontal membranes of the transverse vessels (PI. XXXV. fig. 8).

The tentacles are short but strong. The larger ones are swollen about half-way up.
Jn one place two shorter tentacles occurred between a pair of larger ones (PL XXXV.
fig. 10, in.').

One colony of this species, consisting of about forty individuals, was dredged at Ber-
muda, in shallow water.

Clavelina enormis, Herdman (PL XXXV. figs. 3-j).

Clavelina enormis, Herdman, Prelim. Rep., Prop. Roy. Soc. E<lin., 1879-80, p. 725.

External Appearance. — The individuals are united into a colony by their posterior
ends, which form a common base of irregular shape. The shape of each individual is
rudely oblong. The anterior end is wide, but irregular. The apertures are sessile,
inconspicuous, and not lobed ; they are both at the anterior end.

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

The surface is smooth, but irregular, especially on the posterior part. The colour is
greyish, with a slight brown tinge.

Length of the body of a single individual, 3 cm. ; breadth of the same, 07 cm. ;
height of the colony, 4 cm.

The Test is cartilaginous and opaque ; it is moderately thin on the anterior half ;
posteriorly it is thicker, wrinkled, and incrusted with sand.

The Mantle is well developed.

The Branchial Sac is simple, but rather strong. The transverse vessels are all of one
size, with wide horizontal membranes hanging from them. No internal longitudinal bars
are present. The stigmata are regular, short, and narrow, with rounded ends. The fine
interstigmatic vessels are stout.

The Dorsal Lamina is represented by a series of very large triangular languets, placed
closely.

The Tentacles axe stout, and of two sizes, placed long and short alternately; there
are about twelve of each size.

This is an irregular species, and the only specimen in the collection is almost certainly
to some extent abnormal (PI. XXXV. fig. 3). The united posterior ends of the ascidio-
zooids form a common irregularly-shaped base, which has probably been hypertrophied
by, and owes its irregularity to, adhering to the surface of a mass of Balani.

The test is cartilaginous and strong. It is thick posteriorly and on the base, but is
much thinner at the anterior extremities of the individuals, and on their thoracic or
branchial regions. Two of the individuals are united together along one side by their
tests, which thus form a common investing mass. This is of course an abnormality,
probably caused merely by the very close proximity of the two individuals.

The branchial sac is strong, the stigmata being slight and the transverse and inter-
stigmatic vessels stout ; the latter are usually twice as broad as the stigmata (PI.
XXXV. fig. 4). The horizontal membranes hanging from the transverse vessels are very
wide, and when laid out flat reach three-quarters of the way to the next transverse vessel,
covering the greater part of the row of stigmata between (PL XXXV. fig. 4). The stig-
mata are very regular.

The languets in this species are very different from those seen in Clavelina oblonga
(compare figs. 5 and 8 on PI. XXXV.). Here they are numerous, placed close together,
thin and membranous, triangular in shape, and of large size. They spring from a broad
dorsal membranous band, and their bases are continuous with the broad horizontal
membranes extending round the branchial sac.

One colony of this curious Clavelina, consisting of four adult individuals and several
buds, was obtained at Simon's Bay, Cape of Good Hope, in 10 to 20 fathoms.

GEOGRAPHICAL DISTRIBUTION.

We know as yet very little as to the Geographical Distribution of the Tunicata — far
too little to make generalisations of much value. Still it will be useful to future investi-
gators to tabulate what has been already determined, even if in many cases it shows
merely negative results. But it must be borne clearly in mind, when examining the
following statements, that only a very small area of the sea bottom was examined al
each Station, and that Tunicates might very possibly be abundant in a locality from which
none are here recorded.

I have divided the track of the Challenger round the world into a series of comparat ively
short stages, so as to show roughly the localities between which the different observing
Stations lie. These stages are arranged in the order in which they were traversed by the
expedition, and consequently the Stations are in chronological order, and the lists of
species occur in the order in which they were collected. The chief objects of this arrange-
me it are to show — (1), the approximate positions of the Stations at which Tunicates were
oh lined, and (2), the list of species from each Station.

Between England and the Canary Islands the following Tunicate was dredged : —
Off Gomera, the Canary Islands, 10th February 1873 ; depth, 75 fathoms.
Ciona jl&mingi.

Between the Canary Islands and the West Indies no Tunicata were obtained.

Between the West Indies and Halifax the following Tunicata were obtained : —
Off Bermuda, June 1873 ; in shallow water.
Ascidia nigra.
EctcinKscidta turb'uiata.
Clavelina oblonga.
Station 44, May 2, 1873; Lit. 37° 25' N., long. 71° 40' W.; depth, 1700
fathoms; bottom temperature, l°-7 O; bottom, grey ooze.
Culeolus perlatus.
Station 48, May 8, 1873; lat. 43 2' X., long. 04 2' W.; depth, 51 fathoms;
bottom, rock.

Boltenia elegans.1

The label in the bottle is marked Le Have Bank, Xova Scotia, 75 fathoms.

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

Between Halifax and Bermuda the following Tunicate was dredged : —

Station 49, May 20, 18/3 ; lat. 43° 3'K, long. 63° 39' W.; depth, 83 fathoms ;
bottom temperature, l°-8 C; bottom, gravel and stones.
Ascidia falcigera.

Between Bermuda and the Canary Islands no Tunicata were obtained.

Between the Canary Islands and Bahia the following Tunicate was obtained : —
Off Bahia ; depth, 7 to 20 fathoms.
Poly car pa pilella.

Between Bahia and the Cape of Good Hope no Tunicata were obtained.

Between the Cape of Good Hope and Kerguelen Island the following Tunicata were
collected : —

Simon's Bay, Cape of Good Hope ; depth, 10 to 20 fathoms.
Cynthia pallida.
Paclt yd* 1 1 en a g iga i } tet t .
Clavelina enormis.

Station 142, December 18, 1873; lat. 35° 4' S., long. 18° 37' E.; depth, 150
fathoms ; bottom temperature, 80-3 C. ; bottom, sand.
Ascidia nigra (?).1

Station 146, December 29, 1873 ; lat 46° 46' S., long. 45° 31' E.; depth, 1375
fathoms; bottom temperature 1°'5 C; bottom, globigerina ooze.
Culeolus recumbens.
Corynascidia suh mi.

Station 147, December 30, 1S73; lat, 46° 16' S., long. 48° 27' E.; depth, 1600
fathoms; bottom temperature, 0° '8 C; bottom, globigerina ooze.
Culeolus perlucidus.
Fungulus cinereus.
Baihyoncus mirdbilis.

Between Kerguelen Island and Melbourne, Australia, the following Tunicata were
collected : —

Station 149, off Kerguelen Island, January 1874; depth, 10 to 110 fathoms.
January 19, 1874; Balfour Bay, 20 to 60 fathoms.
Ascidia challengeri.

1 It is the locality which is doubtful, not the name of the species.

REPORT ON THE TUNICATA. 251

20th January 1874 ; Royal Sound, 28 fathoms.
Ascidia clifillnnji'.ri.
vasculosa.
translucida.
29th January 1874 ; oft* London River, 110 fathoms.

Eugyra herguelenensis.
No date; off Kerguelen, 10 to 100 fathoms.
Eugyra Tcerguelenensis.
Styela lactea.
A sc idia ch alle ngeri.
despecta.
Station 150, February 2, 1874; hit, 52° 4' S., long. 71° 22' E.; depth, 1 30
fathoms ; bottom temperature, 1°'8 C; bottom, rock.
Ascopera gigantea.

pedunculate/,.
Molgula pedunculated.
Styela grandis.
convexa.
PolycarjHi minuta.
Ascidia placenta.
Station 160, March 13, 1874 ; lat. 42° 42' S., long. 134° 10' E.; depth, 2G00
fathoms; bottom temperature, 0°-2 C; bottom, red clay.
Styela bythia.

squamosa.
Abyssascidia wyvillii.

Between Melbourne and New Zealand the following Tunicata were collected : —

Station 162, April 2, 1874; off East Moncoeur Island, Bass Strait; depth, 38
to 40 fathoms ; bottom, sand.
Microcosmus polymorph us.

propinquus.
Cynthia Jissa.

hispida.
Styela radicosa.
Polycarpa rigida.

rnolguloides.
Pachychkena ohlonga?
obesa.

1 The label on the bottle containing this spei in* o is marked 86 fathoms.
(zool. ceall. zzv. — part xvir. — 1882.) E 33

THE VOYAGE OF H.M.S. CHALLENGER.

Station 163, April 4, 1874; lat. 3G° 5G' S., long. 150° 30' E.; depth, 2200
fathoms ; bottom temperature, 0°'7 C; bottom, reel clay. Trawled in 120
fathoms,1 off Twofold Bay.
Polyca/rpa radicata.
Ascidia cylindracea.

Port Jackson, Australia ; 17th April to 23rd May 1874 ; 2 to 20 fathoms.
Molgula forbesi.
Cynthia cerebriformis.
irregularis,
complanata.
Styela gyrosa.
exigua.
Polycarpa tinctor.
vivid is.

longisiphonica.
radicata.
Ascidia pyriformis.

Canterbury, New Zealand.

Boltenia pachydermatina.

Between New Zealand and the Fiji Islands the following Tunicata were collected : —

Station 170, July 14, 1S74 ; lat. 29° 55' S., long. 178° 14' W.; depth, 520
fathoms ; bottom temperature, 6°"0 C; bottom, rock.
Culeolus wyvillc-thomson i.

Kandavu, the Fiji Islands ; July 27, 1S74.
Cynthia pallida.

Between the Fiji Islands and Hong Kong, China, the following Tunicata were
dredo-ed : —

Station 18G, September 8, 1874; lat. 10° 30' S., long. 142° 18' E.; depth, 8
fathoms ; bottom, coral sand.
Cynthia arenosa.
formosa.2

Station 188, September 10, 1874; lat, 9° 59' S., long. 139° 42' E.; depth, 28
fathoms ; bottom, mud.
Microcosm us helleri.

1 The two Asuidians tiro almost certainly from this depth.
- This species is labelled "Torres Straits, 3 to 11 fathoms."

RErORT ON THE TUNICATA. 253

Station 192, September 26, 1874; off Ki Island, lat. 5° 42' 8., lung. 132 25'E.;
Noon; depth, 129 fathoms; bottom, mud.
Polycarpa quadrata.

Ecteinascidia crassa.

Banda, Malay Archipelago, October 1, 1874; depth, 17 fathoms.
Polycarpa sulcata.
Ecteinascidia Jusca.

Between Hong Kong and New Guinea the following Tunicata were collected : —
Hong Kong, China; depth, 10 fathoms.
Corella japonica.

Station 208, January 17, 1875; lat. 11° 37' N, long. 123° 32' E.; depth, 18
fathoms ; bottom, mud.

Polycarpa irreg ula ris.

Station 212, January 30, 1875 ; lat, 6° 55' N,long. 122° 15' E.; depth, 10, 14
and 20 fathoms ; bottom, sand.
Polycarpa peek tta.

Between New Guinea and Japan the following Tunicata were dredged : —

Station 233a, May 17 to 19, 1875; Kobe, Japan; lat. 34° 35' N., long. 135
10' E.; depth, 8 fathoms and 50 fathoms; bottom, mud and sand.
Styela clava.
Corella japonica.
Ciona savignyi.

Off Yokohama, Japan; shallow water.
Corella japonica.

Between Japan and the Sandwich Islands the following Tunicata were obtained : —

Station 241, June 23, 1875; lat. 35° 41' N., long. 157° 42' E.; depth, 2300
fathoms ; bottom temperature, 1°"1 C. ; bottom, red clay.
Culeolus murray i.

Station 248, July 5, 1875; lat. 37° 41' N, long. 177° 4' W.; depth, 2900
fathoms; bottom temperature, l°'l C; bottom, red clay.
Hypobyth ins calyco< h '■$.

Between the Sandwich Islands anil Valparaiso the following Tunicata were collected : —
Papiete Harbour, Tahiti, Society Islands; depth, 10 to 20 fathoms.
Cynthia papietensis.

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

Station 271, September 6, 1875 ; lat. 0° 33' S., long. 151° 34' W.; depth, 2425
fathoms ; bottom temperature, 1°'0 C. ; bottom, globigerina ooze.
Culeolus moseleyi.

Station 299, December 14, 1875; lat. 33° 31' S., long. 74° 43' W.; depth,
21 GO fathoms ; bottom temperature, 1°"1 C; bottom, grey mud.
Corynascidia suhmi.

Between Valparaiso and the Falkland Islands the following Tunicata were dredged : —
Station 311, January 11, 187G ; hit, 52° 50' S., long. 73° 53' W.; depth, 245
fathoms ; bottom temperature, 7°'7 C. ; bottom, mud.
Ascidia tenera.
Station 312, January 13, 1876 ; lat, 53° 38' S., long. 70° 5G' W.; depth, 15 to
10 fathoms ; bottom, mud.
Boltenia legumen.

Station 313, January 20, 1876; lat, 52° 20' S., long., 68° 0'W.; depth, 55
fathoms ; bottom temperature, 8°-8 C; bottom, sand.
Molgula gigantea.
Ascidia meridionalis.

Between the Falkland Islands and Buenos Ayres, South America, the following
Tunicata were collected : —

Station 315, January 26, 27, 28, 1876 ; lat. 51° 40' S., long. 57° 50' W.; depth,
5 to 1 2 fathoms ; bottom, sand and gravel.
Molgula grcga ria.

horrida.
Boltenia legumen.
Station 316, February 3, 1876 ; lat, 51° 32' S., long. 58° 6' W. ; depth, 4 to 5
fathoms ; bottom, mud.
Boltenia legumen.

Station 320, February 14, 1876 ; lat. 37° 17' S., long. 53° 52' W. (off the coast
of Buenos Ayres) ; depth, 600 fathoms ; bottom temperature, 2°-7 C. ;
bottom, hard ground.

Molgida pyriformis.
Styela flava.
oblonga.
glans.
Ascidia meridionalis.

tenera.
Ilypobythius moseleyi.

REPORT ON THE TUN 1< ATA. 255

Between Buenos Ayres and England no Tunieata were obtained.

The above arrangement has given, of course, information ;is to llie bathj-mctrica]
distribution, as well as the geographical, bnt a better general notion of the latter alorn
may be obtained by grouping the above Stations at which Tunieata were collected int..
geographical regions, as is shown in the following list.1 The principal object in this
case is to give the Tunicate Fauna of each of these regions, as known from the
Challenger investigations.

In the North Atlantic (East) the following Tunicate was found : —
Off Gomera, Canary Islands.
Qiona Jlemingi.

In the North Atlantic (West) the following Tunieata were obtained : —
Off Bermuda.

Ascidia nigra.

Ecteinascidia turbinata.

Clavelina oblonga.
At Station 44.

Cideolus perlatus.
At Station 48.

Boltenia elegans.
At Station 49.

Ascidia falcigcra.

Off the east coast of South America the following Tunicate was dredged: —
Off Bahia.

Poly car pa pilella.

At the Cape of Good Hope and neighbourhood the following Tunieata were
collected : —

At Simon's Bay.

Cynthia pallida.

Pachychlcena gigantea,

Clavelina enormis.
At Station 142 (?).

Ascidia nigra.

' lathis case all details as to the exact position, depth, temperature, &c, of the Stations b
these have already been given in full in the first lint.

251] THE VOYAGE OF H.M.S. CHALLENGER.

t Iff Keronelen Island and in the neighbourhood the following Tunicata were collected:

At Station 14G.

Ci i leolus recumben s .
Corynascidia suhmi.
At Station 147.

Ci i leol us perl itcid us.
Fungulus einereus.
Baihyoncus mhxtbilis.
At Station 149, Kerguelen Island.
Eugyra kergudenensis.
Styela lactea.
Ascidia despecta.

challenge ri.
vasculosa.
translucida.
At Station 150.

Ascopera gigantea.

pedunculated
Molgula pedunculata.
Styela grandis.
convexa.
Polycarpa minuta.
Ascidia placenta.

Off South Australia and New Zealand the following Tunicata were collected :—

At Station 160.

Styela bythia.

squamosa.
j. 1 byss< iscidia try villi i.

At Station 162.

Microcosmus polymorpluis.

propinquus.
Cynthia Jissa.

hispida.
Styela radicosa.
Polycarpa rigida.

molguloides.
Pachychlcena oblonga.
obesa.

REPORT ON THE TUN H 'ATA. 25i

At Station 1G3.

Polycarpa radicata.

A.<<-iilin ci/Iijulrwen.

At Port Jackson, Australia.
Molgula forbesi.
Cynthia cerebriformis.
irregularis.
complanata.
Styela gyrosa.
exigua.
Polycarpa tinctor.
viridis.

longisiphonica.
radicata.
Ascidia piriformis.

From Canterbury, New Zealand.

Boltenia pachydermatina.

In the Southern Pacific Area the following Tunicata were dredged : —

At Station 1 70.

Culeolus wyville-thomsoni.

At Kandavu, Fiji Islands.
Cynthia pallida.

At Station 271.

Culeolus rnoseleyi.

In the seas of the Malay Archipelago the following Tunicata were dredged : —

At Station 186.

Cynthia arenosa.
formosa.

At Station 188.

Microcosm us helleri.

At Station 192.

Polycarpa quadrata.
Ecteinascidia crassa.

•2.38 THE VOYAGE OF H.M.S. CHALLENGER.

At Banda.

Polycarpa sulcata.
Ecteinascidia fuscu.

Off Hong Kong, China.

Corella japon ica.

At Station 208.

Polycarpa irregularis.

At Station 212.

Polycarpa pedata.

Off Japan the following Timicata were dredged : —

At Station 233a.

Styela clava.
Corella japon ica.
Ciona savignyi.

Off Yokohama,

Corella japonica.

In the Northern Pacific Area the followine- Tunicata were dredged : —

At Station 241.

Culeolus murrayi.

At Station 248.

If y j >obyt hius cali/codes.

In Papiete Harbour, Tahiti, Society Islands.
Cynthia papietensis.

Off the Southern end of South America the following Tunicata were collected

At Station 299.

Corynascidia suhmi.

At Station 311.

Ascidia tenera.

At Station 312.

Bot 'tenia legumen.

At Station 313.

Molgula gigantea.

Ascidia meridional is.

REPORT ON THE TUNICATA. 259

At Station 315.

Molgula grega/ria.
horrida,

Boltenia legumen.

At Station 316.

Boltenia legumen.

At Station 320.

Molgula pyriform is.
Styela fiava.

oblonga.
glans.
Ascidia meridionalis.

tenera.
Hypobythius moseleyi.

This list seems to show that Tunicata are very much more abundant at some localities
(e. g., Station 150, Station 162 and Station 320) than at others; but it must be noted
that in some cases, such as Kerguelen Island, the length of the list is caused, to a
certain extent, by the much greater time spent by the expedition in investigating that
region. Some of the areas in the above list, however, at which there were a large number
of observing stations, show singularly few Ascidians. For example, in the eastern portion
of the North Atlantic, and off the east coast of South America, only a single species was
obtained in each locality. Then again, only three species were found in the South Pacific
Area, and only two in the North Pacific. On the other hand, some much smaller areas
have a long list of species, — for example, fifteen species were obtained in the neighbour-
hood of Kerguelen Island, and twenty-three in the area comprising Australia and New
Zealand.

In the table given below, the geographical regions already made use of have been
grouped together to form seven great areas, namely: — the North Atlantic, the South
Atlantic, the Southern Ocean (the region lying to the south of the Indian Ocean, and
including Kerguelen Island), the seas of the Malay Archipelago (the area lying between
Australia and China), the North Pacific, the South Pacific, and the shores of the southern
end of South America. This last area lias been separated from the South Atlantic and
South Pacific Oceans, to which it should strictly belong, because of the large number of
Tunicata found in the neighbourhood of Cape Horn, and the difficulty of dividing them
into an east coast and a west coast series.

As the species are arranged in systematic order, this table shows at a glance the
distribution of any particular species, genus, or family in the great ocean basins.

(zool. CHALL. EXP. PART XVII. 1882.) R 34

260

THE VOYAGE OF H.M.S. CHALLENGER.

Table showing the Distribution of the Families, Genera, and Species of
asctdle slmplices throughout the great ocean basins.

Species.

Family Molgulidje,

Ascopera gigantea,

pedunculata,

Molgula gigantea,
gregaria,
pedunculata,
horrida, .
forbesi, .
pyriformis,

Eugyra kerguelenensis,

Family Cyntiiiidj;

Boltenia elegans, .
legumen, .
pachydermatina,
Culeolus murrayi, .

wyville-tTwmsoni,
recti mbrns,
perlucidus,
perlatus, .
moseleyi, .
FunguVus cinereus,
Microcosmus helleri,

propinquus,
polymorphic,
Cynthia cerebriformis,
fissa,

formosa, .
arenosa, .
irregularis,
pallida, .
papietensis,
complanata,
hispida, .
Styela bythia,

squamosa, .
grandis,
gyrosa,
convexa,

Atlantic. Atlantic.

North

South

Southern
( Icean,

+
+

+
+

+
+

4.
Ssas mi
Malay
Archip.

+
+

North
Pacific.

South
Pacific.

7.

Seas of

South

America.

+

+
+
+
+

+
+
+
+

+
+

+

+

REPORT ON THE TUNIC ATA.

201

Species.

Styi la lactca,

exigua,

clava, .

radicosa,

oblonga,

Jlava, .

glum, .
Bathyoneus mirabilis,
Polycarpa pedata, .
viridis, .
tinctor, .
minuta,
molguloidet
quadrata,
pUella, .
rigida, .
longisiphoniea
irregular!*,
sulcata,
radicata,

Family Ascidudje.

Corynascidia suhmi,

Corella japonica, .

Abyssascidia, wyvillii,

Pachychlcena oblonga,
obesa,
gigantea,

Ascidia rm ridionalis,
chdllengeri,
vasculosa,
translucida,
tenera,
pyriformis,
faleigera, .
cylindracea,
despecta, .
nigra,
placenta, .

Hypobythius calyco Us,
moseh yi,

Giona flemingi,
savignyi,

North
Atlantic

+

South Southern
Atlantic, Ocean.

4.

.-. i . ol

Blab]

Archil).

+
+
+

North

South
Pacific.

Seat i.f

+
+

+
+

+
+

+

+
+

+
+

+
+
+

262

THE VOYAGE OF H.M.S. CHALLENGER.

Species.

1.

North
Atlantic.

2.

Soul li
Atlantic.

3.

Sunt hciu
Ocean.

4.
Seas of
Malay
Arehip.

5.

North
Pacific.

6.

South
Pacific.

7.

Seas of

South

America.

Family Clavelinid2e.

Ecteinascidia crassa, ......

+

fusca, ......

+

turbinata, ......

+

Clavelina dblonga, .......

+

enormis, ......

+

The preceding table shows — first, that the Challenger expedition obtained Simple
Ascidians in all of the seven great areas into which the seas of the globe have been
divided ; and secondly, that they were much more abundant in the Southern Pacific
Ocean1 than in any of the other regions.

Of the Molgulidse, Ascopera and Eugyra are confined to the Southern Ocean, while
Molgula is found in the Southern Ocean and also in the South Pacific, and round the
southern end of South America. Hence the family is not represented 2 in the Atlantic
Ocean, the North Pacific, and the Seas of the Malay Archipelago.

The great family Cynthiidas has representatives in all the oceanic areas — and the
Bolteninse also occupy them all, with the exception of the South Atlantic and the Seas of
the Malay Archipelago.

The Cynthinse are chiefly from the South Pacific area, but are also represented in the
North Pacific, the South Atlantic, and the Malay regions, while they are entirely absent
in the North Atlantic, the Southern Ocean, and round the southern end of America.

The fctyelinse are also chiefly from the South Pacific Ocean, but are represented in all
the other areas, with the exception of the North Atlantic.

The Ascidiidas arc entirely wanting only from the Seas of the Malay Archipelago, and
they are pretty equally distributed over the other six regions.

The Clavelinidse, finally, occur in the North Atlantic, the South Atlantic, and the
Malay region, and are unrepresented in the remaining four areas.

In the following table, the last illustrating the geographical distribution of the Ascidias
Simplices, the occurrence of the different genera and species according to the latitude is

1 This region is of much greater extent than the " Southern Pacific Area " used previously (page 257), and
includes, in addition to it, the Australian region, in which a large number of species were obtained.
- All these statements as to distribution refer, of course, to the Challenger collection only.

REPORT ON THE TTJNICATA.

2G3

shown in both northern and southern hemispheres. A + means merely that the species
opposite which it is placed was found by the Challenger expedition somewhere between
the limits of latitude which the column represents. Hence it may indicate more than
one occurrence of the same species.

North Latitude.

45°-40<

+

40°-30° 30°-20° 20°-10°10°-0

Genus.

Species.

Ascopera gigantea, .
/,, diu/rtdtita,

Molgula giganlea,
gregaria,

pedunmlata,

horrida,

forbad,

pyriformis,
Eugyra Jcerguelenensis,
Boltenia elegans,

legumen,

liaclnjtlfniiatina
Culeolus murrayi, .

wyoille-thomsoni,

recumbens,

[icrhiruhix,

perlatus,

moseleyi,
Fungulus cineri us,
Microcosmit* In lleri,

prqpinquus,
polymorphus,
Cynthia cerebriformis,

fissa, .

furmosa,

arenosa,

inrgidarin, .

pallida,

papii /- nsis,

complanata,

hispida,
Styela byfhia,

squamosa,

tir<in>l is,

gyrosa, .
convexa,
laetea, .

South Latitude.

0°-10° 10°-20° 20°-30° 30°-40° 40°-45'

+

+

+
+

+

+
+

+
+
+
+

+
+

+
+

+
+
+
+
+
+

+
+

+
+

+
+
+

+
+

>6 1

THE VOYAGE OF H.M.S. CHALLENGER.

North Latitude.

45°-40° 40°-30° 30°-20° 20°-10° 10°-0'

+

+

+
+

+
+

Genus. Species.

Sty/a exigua, .
clava, .
gblonga,
flava,
glaiis, .
radicosa,
Polycarpa viridis, .
Hnctor, .
m in a ta, .
molguloides,
quadrata,
pilella, .
rig/da,

longisiphonicc
irregularis,
sulcata, .
pedata, .
radicata,
Batli yoncus mirabilis,
Corynascidia suh m i,
Gorella japonica,
A byssascit lia wyvillii,
Paehychlama obesa,

giganlea,
oblomga,
Ascidia cludlsngeri, .
vasculosa, .
placenta,
nigra,

meridionalis,
falcigera, .
/<!< era,
translucida,
cylindracea,
despecta,
pyriformis,
dona flemingi,
savignyi,
Hypobyihius calycodes,

mostleyi,
< 'I'irclma enormis, .

oblouga,
Ecieinascidia turbinata,
fusca, .
ei'assa, .

South Latitude.

0°-10° 10'-20o 20°-30° 30°-40° '40°-5&

+
+

+

+
+
+
+
+
+

+
+

+
+
+

+
+

+

+
+

+

+
+
+

+
+

REPORT ON THE TUNICATA. 265

This table brings out very forcibly — first, the greal preponderance of Ascidians in
the southern over the northern hemisphere, there being about six times as many entri
on the right hand side of the table as on the left; and secondly, the atrandanee of
Tunicata in the far south, the two last divisions on the right hand side (30° to 40° and
40° to 55°) 25° in all, containing each of them more entries than all the other divisions,
both north and south latitude, taken together.

Consequently, it appears from the Challenger investigations that Simple Ascidians are
not abundant in the northern hemisphere, and are comparatively scarce in tropical latitudes,
while they attain their greatest numerical development in southern temperate regions.

Taking up particular groups of species, we find that the Challenger Molgulidae were
all obtained in the southern hemisphere, and between the latitudes of 30° and 55° S.
Two species of Molgula were found between 30° and 40° S., while all the rest, including
the genera Ascopera and Eugyra, and most of the species of Molgula, are from latitudes
between 40° and 55° S.

The Cynthiidse range over both hemispheres, extending from between 40° and 45°
north latitude, to between 50° and 55° south latitude. The sub-family Bolteninse has
an equally extended range, but is most abundant in the far south. The number of
species found in the extreme right hand column (40° and 55° south latitude) equal
those in all the other columns put together.

In the genus Boltenia, one species occurs in the extreme north, while the other two
are from far south, the genus being unrepresented in intermediate latitudes.

The genus Culeolus has also a very considerable horizontal range, two of the species,
Culeolus murrayi and Culeolus perlatus, being found in the northern hemisphere, while
the remaining four are from the southern. Those in the northern seas are from the
temperate zone, while of the southern forms, one, Culeolus moseleyi, is from near the
equator ; one, Culeolus wyville-thomsom, from between 20° and 30° south latitude, and
the remaining two species are from much further south. The nearly allied Fungvlus
einereus is also from high latitudes in the southern hemisphere.

The sub-family CynthinaB is, with the exception of Cynthia pcupietensis, confined to
the southern hemisphere, but none extend beyond the parallel of 40°. Microcosmus bas
one species near the equator, while the remaining two are from much further south. In
the genus Cynthia, also, most of the species are from the Southern temperate zone, three
only being found in tropical latitudes.

The sub-family Styelinse is represented by three species north of the equator, while the
remaining twenty-two are from the southern hemisphere, and the great majority of them
from south of 30° S. latitude.

In the genus- Styela, all the species, with the exception of one (Styela clava) from
the northern hemisphere, are from the southern temperate region, and most of them are
from between the parallels of 30° and 40° S.

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

The single species of Bathyoncus is from far south.

Polyca/rpa has two representatives in the northern hemisphere, and three in the
southern tropical zone, while the remaining seven species are from the southern temperate
regions.

Of the seven genera of the Ascidiidse, two, Corella and dona, are confined to the
northern hemisphere, and three, Abyssascidia, Corynascidia, and Pachychlcena, are
purely southern.

Ascidia is only represented by one species in the northern hemisphere, the remaining
ten species being confined to southern temperate regions. None of the Challenger
Ascidiidse occur in the tropics.

Hypobythhis has one species in the northern hemisphere and one in the southern,
both at considerable distances from the equator.

The Clavelinidse are almost equally represented in the two hemispheres, having two
species north of the equator and three to the south. Clavelina has one species in each
temperate zone, and is not represented at intermediate latitudes. Ecteinascidia, finally,
has one species [Ecteinascidia turbinata) in the northern temperate region, while the
remaining two are from the southern tropics.

BATHYMET1UCAL DISTRIBUTION.

The remarks made at the commencement of the section upon Geographical Distribu-
tion in regard to the uncertainty of the results, on account of tin- scantiness of our know-
ledge, apply with ecpial force to the question of distribution in depth.

The first table given below shows the range in depth of the specie.-,, genera, and
families of Simple Ascidians. The names are arranged systematically, and the extreme
limits of depth at which each species has been found are given.

The depth is not known in the case of Boltenia pachydxvrmati?ia, as t lie two specimens
of that species in the collection were presented to the expedition at Wellington,
New Zealand.

Family, Genus, and Species.

Range in Depth.

MOLGULID.E

Ascopera gigantea, .....

L50 fathoms.

pedunculata,

150

Mulgula gigantea,

55 .,

gregaria,

5-10 „

pedunculata, .

150 „

horrida,

5-12 „

forbesi, .

2-10 „

pyriformis,

600

Eugyra kr.rguel< nensis,

10-100

CyXTHIID/E —

Biilti/nid fji'gitn.i, ......

51

legumen,

1 -'-•' „

pachydermatina,

(?)

Culeolus murrayi,

2300

wyville-thomsoni,

630

recumbent,

1375

perlucidus,

L600

perlatus,

1700 „

moseleyi,

2425

Fnngulus cinereiis,

1600

Microcosmus helb ri,

28 „

propinquits,

38-40

pulymorp/ins,

38 10

(Z ,. CHALL. EXP. — PAhT XVII. — 1882.)

i; 35

268

THE VOYAGE OF H.M.S. CHALLENGER.

Family, Genus, and Species.

Range in Depth.

Cynthia cerehriformis, .....

G-l.j fathoms.

fissa,

38-40

formosa,

3-11

arenosa,

1-8 „

irregularis, .

2-10

pallida,

10-20

jiilpii fensis,

10-20

cornplanata, .

6 „

h ispida,

38-40

Styela byfhia,

2600

squamosa,

2600

grand!*, .

150

gyrosa, .

G

convexa, .

150

lactea,

10-100

exi'jua,

2-10 „

clava,

8-50

oblonga, .

600

flava,

600

glans,

600

radicosa, .

38-40

Bathyoncus m irabilis,

1600

Polyaarpa viridis,

2-15

tindor,

2-15

minuta,

150

molguloides,

38-40

quadrata, .

129

pilella,

7-20

rigida,

38-40

longisiphonica,

6-15

irregularis,

18

sulcata,

17

pi'data,

10-20

radieata,

6 and 120

ASCIDIID.E

Corynascidia mhmi, .....

1375-2160

Corella japoniaa,

8-50 „

Abyssascidia wyvillii, .

2600

PachycMcena obesa,

38-40

gigantea,

10-20 „

oblonga,

38-40

Ascidia challengeri,

10-60

vasciilosa.

28 „

placenta,

150 „

nigra, .

Shallow water, and 150 fathoms.

REPORT ON THE TUNICATA.

269

Family, Genus, and Species.

Range in 1 lepth.

Ascidia meridionalis,
falcigera,
tenera, .
translueida,

55 and 000 fathoms.

83 „
245 and GOO

28

ri/Iindnirra,

despecta,

pyriformw,

Hypobijtliins ealycodes,
moseleyi,

Ciona flemini/i, .

120
10-100

6 „
2900
600 „
75

savignyi, .

8-50

Clavelinid.e —

Ecteinascidia crassa, .....

] 29 fathoms.

fusca,
turhinata,

17 „
Shallow water.

Clavelina oblonga,
etwrmis,

10-20 fathoms.

From this table it is a simple matter to determine the range in depth of any
particular genus, e.g. : —

Molgula . extends from 2 to 600 fathoms.

Styela . 2 to 2600 „

The four families of Ascidiae Simplices are found to have the following limits : —

The Molg-ulidaa range from the shore to 600 fathoms.
The Cynthiidaa „ „ 2600 „

The Ascidiidse
The Clavelinidao

2600
L29

Hence it appears that there is no family peculiar to deep water, as inch of the four has
species ranging from a few fathoms of water downwards. The Clavelinidae have as yet
not been found at a depth greater than 129 fathoms, and most of the species inhabit much
shallower water. If Ecteinascidia crassa be excepted, the Challenger specimens of the
Clavelinidas are all from less than 20 fathoms.

The MolguhVhe are represented in the abyssal zone 1 by Molgula pyriformis, at 600
fathoms, while the remaining species range between shallow water and 150 fathoms.

The Cynthiidse and Ascidiidse have both a much wider distribution in depth, and
each of them contains genera whieli are peculiarly abyssal. In the Cynthiidae the sub-

1 500 fathoms and upwards.

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

families Bolteninae and Styelinae range into deep water, while the Cynthinse are all found
in less than 40 fathoms. Among the Bolteninae, Boltenia is from shallow water, while
Culeolus is a peculiarly deep-water genus, but has a considerable range, viz., from 630 to
2425 fathoms. Five of the species are from upwards of 1000 fathoms, four from over
1500, and two from upwards of 2000. Thus they all belong to the abyssal fauna.
Fungulus, which is closely allied to Culeolus, is also a deep-water form.

Iu the StyelinaBj Styela has a range of from shallow water up to 2600 fathoms.
Five species belong to the abyssal fauna, three of them being from 600 fathoms, and two
from 2600. The remaining species of the genus are all from less than 150 fathoms.

Polycarpa is a shallow-water genus, ranging from quite shallow water to 150 fathoms,
and therefore having no representative in the abyssal zone. The remaining genus of the
Styelinse, Bathyoncus, is the only peculiarly deep-water genus in the sub-family. It was
found at a depth of 1600 fathoms.

In the Ascidiidae the majority of the species are from small depths, but two genera,
Corynascidia and Abyssascidia, are peculiar to very deep water, while two species of
Ascidia (Ascidia meridionalis and Ascidia tenera) also range into the abyssal zone.
The remaining species are distributed from shallow water up to 150 fathoms. The species
of Corella, Pachychlcena and Ciong are from depths of less than 100 fathoms.

If the range of depth at which Simple Ascidians were found (from the shore down to
2600 fathoms) be divided into five zones, the following results will be arrived at : —

I. — Between the shore and 50 fathoms forty-seven species were found, viz. : —

Molgula gregaria.

horrida.

forbesi.
Eugyra kerguelenensis.
Boltenia legumen.
Microcosmus h elleri.

propinquus.
polymorphus.
Cynthia hispid a.

cerebriformis.

Jissa.

formosa.

arenosa.

irregularis.

complanata,

pallida.

papietensis.

REPORT ON THE TUNICATA. 271

St ye/ 1 1 gyrosa.
lactea.
i .liijnu.
clava.
radicosa.
Polycarpa tinvtor.
viridis.

longisiphonica.
irregularis.
sulcata.
pilella.
molguhides.
rigida.
pedata.
radicata.
Co rella japonica.
Pachychlcena obest u

gigantea.
oblonga.
Ascidia challengeri.
vasculosa.
nigra,
translucida.
despecta.
pyriformis.
Ciona savignyi.
Ecteinascidia t urbinata.

fusca.
Clavelina enonms.
oblonga.

In this list thirteen genera and four families are represented.

II. Between 50 fathoms and 500 fathoms twenty-two species were found, viz. : —

Ascopera gigantea.

pedunculata.
Molgula gigantea.

pedunculata.
Eugyra kerguelenensis.
Bol tenia elegans.

•272 THE VOYAGE OF H.M.S. CHALLENGER.

Styela grandis.

lactea.
convexa.
Polycarpa quadrata.
minuta.
radicata.
Ascidia ckaMengeri.
placenta.
11 igra.

tneridionalis.
falcigera.
tenera.
cylindracea.
despecta.
Ciona flemingi.
Ecteinascidia crassa.

In this list nine genera and four families are represented.

III. — Between 500 fathoms and 1000 fathoms eight species were found, viz.: —

Molgida piriformis.
Culeolus ivyville-thomsoni.
Styela Jlava.

oblonga.

glans.
Ascidia meridionalis.

tenera.
Hypobytlwis moseleyi.

In this list five genera and three families are represented.

IV. — Between 1000 fathoms and 2000 fathoms six species were found, viz.: —

Culeolus recuml>ens.

perlucidus.

perlatus.
Fwngulus cinereus.
Buthyoncus mirabilis.
Corynascidia sidimi.

In this list four genera and two families are represented.

REPORT ON THE TUNICATA. 273

V. — Between 2000 fathoms and 3000 fathoms seven species were found, viz.: —

CiiJcolusmurriiiji.
moseleyi.
Styela bythia.

squamosa.
Corynascidia suhmi.
Abyssascidia wyvillii.
Hypobythius calycodes.

In this list five genera and two families are represented.

From these lists it appears that Simple Ascidians are much more common in shallow
than in deep water, and that comparatively few — twenty species in all — extend into
the abyssal zone, while more than twice as many species are found between the shore
and 50 fathoms as between 50 fathoms and 500.

These lists, however, do not represent accurately the whole state of affairs, as they do
not take into account the greater facilities for collecting in shallow water, nor yet the
relative numbers of the deep and the shallow-water dredgings performed during the
voyage.

Hence the following list, showing the number of dredgings taken by the expedition
in the different zones, and the proportion of them at which Simple Ascidians were found,
is necessary, in order to give a complete idea of the bathymetrical distribution : —

In 32 dredgings at from 0-50 fathoms, Ascidias Simplices occurred 10 times,1 or at 31 per cent, of the Stations.
„ 51 „ 50-500 „ „ 10 „ 20

„ 23 „ 500-1000 „ „ 2 „ 9

„ 94 „ 1000-2000 „ „ 3 „ 3

„ 1G1 „ 2000-3000 „ „ 5 „ 3

The column of percentages brings out clearly that although Simple Ascidians extend
into very deep water, and are fairly well represented in the abyssal zone, still they are
chiefly a shallow- water group, and attain their greatest numerical development immedi-
ately around coasts in a few fathoms of water.

It seems impossible to establish any relation between the occurrence of Simple
Ascidians and the nature of the bottom. The shallow-water forms appear to affect mud

1 In addition to this, Simple Ascidians were collected from depths le a than 50 fathoms al nine 1 calities which

are not given in the list of Stations, viz. :— Bermuda, Bahia, Simon's Bay, Port Jackson, Kandavu, Bauda, Hoi -
Koiifr, Yokohama, and Tahiti.

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

or sandy mud, but those from deep water are found on various kinds of deposit, including
" grey ooze," " globigerina ooze," " red clay," and " hard ground."

Temperature also appears to have little influence upon the distribution of the
Ascidise Simplices, as the temperatures of their localities range from nearly freezing point
upwards.

SUMMARY AND GENERAL REMARKS.

As I intend to reserve the discussion of any questions which affect the Tunicata as a class
till the conclusion of the second part of this Report, I have confined myself in the presenl
section to a brief summary of the chief additions made by the Challenger expedition to
our knowledge of the Simple Ascidians ; to a few remarks upon structural points of
novelty or interest, which are not sufficiently brought out in the systematic part ; and to a
discussion of the phylogenetic relations of the Ascidise Simplices, so far as our present
knowledge of the group will permit us to make such investigations.

In the following pages the remarks upon the different species are arranged in the
order in which the genera occur in the preceding systematic part of the work, beginning
with the highest and working downwards.

Among the Molgulidse the most interesting new forms are the two species of Ascopera.
Like so many of the species from deep water, they have the posterior end of the body
prolonged to form a peduncle by which the animal is attached. In this respect, and in
having no hairs upon the test, and no adhering sand grains, they differ from typical
Molgulids. These peculiarities are, however, found in one of the species referred to the
genus Molgula, namely, Molgula pedunculata. The two species of Ascopera differ in
all their internal organs as well as in external appearance. The branchial sacs are very
distinct. That of Ascopera pedunculata (PL II. fig. 5) is regular, and has rather the
appearance of the branchial sac of one of the Cynthiidse, on account of the tendency of
the stigmata to lie in transverse rows. In Ascopera gigantea, on the other hand, they
are always irregularly curved and placed (PI. II. fig. 1), and consequently the sac in this
species has more of the characteristically Molgulid appearance.

Molgula pedunculata shows affinities with Ascopera, not only in having a short
peduncle, and in the absence of adhering sand, but also in the structure of the branchial
sac, which has the stigmata in some places very slightly curved, and arranged in trans-
verse rows very much as in Ascopera pedunculata (compare PL V. fig. 3, and PL II.
fig. 5). However, this Cynthiad arrangement is continued for short distances only.

The only other branchial sac among the Molgulidse which requires special notice is
that of Molgula pyriformis (PL VI. fig. 2). The longitudinal folds are in a rudimentaxy
condition, exactly corresponding to that found in Styela oblonga and Styela glans,
among the Cynthiidse. The stigmatic portion of the sac does not enter into the
folds, which are represented merely by longitudinal tracts, along which the interna]

(ZOOL. CHALL. EXP. — PART XVII. — 1882.) R 36

27 6 THE VOYAGE OF H.M.S. CHALLENGER.

longitudinal bars are more than usually close. In Molgula piriformis there are only three
internal longitudinal bars in each of these regions, but, as I have shown elsewhere,1 in
the case of Styela grossularia, a more rudimentary condition even may be traced through
a series of gentle gradations into a well-developed fold.

The dorsal tubercle is very variable in the Molgulidae. In typical species of the genus
Molgula it is usually cordate or reniform in outline, with both horns coded inwards, but
not forming large spirals. In Molgula forbesi (PL V. fig. 11), we find a comparatively
simple tubercle, with one horn turned out and one in, while in Molgula gigantea, and in
Ascopera gigantea (PL III. fig. 5), the spirals are very large, quite as large as in any of
the Cynthiidae, which are usually supposed to have the most complicated tubercles. In
Molgula pyriformis (PL VI. fig. 3), and Eugyra kerguelenensis (PL VI. fig. 9), on the
other hand, the dorsal tubercle is found in the simplest possible condition, namely, as
the slightly enlarged aperture of the duct from the neural gland bounded by a plain
prominent margin, circular in the one case, and quadrangular in the other. It is rather
puzzling to find this simple condition of the dorsal tubercle in the most highly
differentiated family of Simple Ascidians, and it does not in the least help us towards a
solution of the question why in so many other forms the aperture of the duct of a gland
should have acquired such a complicated structure. However, the complexity of the
dorsal tubercle is evidently not correlated with that of the other organs, as we sometimes
find it in very different conditions in two species which, from the rest of their structure,
seem closely allied.

Among the Cynthiidae the sub-family Bolteninae contains the greatest novelties. It
has always been an interesting group, as it contains the rarest and least known forms.
The Challenger expedition has revealed the existence of a small group of pedunculated
Ascidians, apparently confined to great depths, and having several striking peculiarities.
These are more nearly allied to Boltenia than to any other previously known genus, and
have been placed in two closely related new genera — Culeolus and Fungulus.

On account of the great interest attaching to these forms, I have gone into very con-
siderable detail in their description, and especially in that of Culeolus murrayi, the only
large species of which there were two specimens in the collection.

As I have shown in the tables given in the two preceding sections of the Report, both
the horizontal and the vertical distributions are wide in this genus. The localities of the
species are widely separated, and occupy all the great oceans: — one species being from
the North Atlantic, off the east coast of North America ; two from the Southern Ocean,
between the Cape of Good Hope and Kerguelen Island ; one from the South Pacific, to
the north of the Kermadec Islands ; one from the North Pacific, east of Japan2 ; and one

1 On Individual Variation in Simple Ascidians, Trans. Lit. and Phil. Soc, Liverpool, 1882.

2 While these sheets were passing through the press, I received from the Challenger Office a tube containing a
small specimen of a Culeolus from this locality (Station 241, 2300 fathoms). It is evidently a new species, and will be
described and figured in the second part of this Report.

REPORT ON THE TUNICATA. 277

from the centre of the Pacific Ocean, on the equator. It is a curious fact that not more
than one of the species was obtained at any single locality. The only two from the same
neighbourhood are Culeolus recumbens and Culeolus perlucidus, which were obtained at
consecutive Stations (Nos. 146 and 147) in the Southern Ocean.1 The first of these
stations is the most southern locality for the genus, while Station 44, the locality for
Culeolus perlatus, is the most northern extension.

Culeolus wyville-thomsoni, which is by far the least deep form of the genus, has a
thicker and more ordinary looking test than any of the other species. Otherwise the
depth seems to have no effect, the two deepest forms, Culeolus murnvji and Culeolus
moseleyi, having thick, opaque tests, while much the most fragde and transparent form
is Culeolus perlucidus, from the intermediate depth of 1600 fathoms.

It seems impossible to establish any relation between the nature of the bottom and
the occurrence of this genus. Three of the localities are marked globigerin a ooze. Two
of these, Stations 146 and 147, are very pure and typical examples of this deposit, while
the third, Station 271, has a considerable admixture of Radiolarians and Diatoms. Of the
three remaining localities, one, Station 241, is a red clay; another, Station 170, is a
volcanic deposit, composed of fragments of rock and pumice, with a little mud ; while the
last, Station 44, is a blue mud, formed of continental debris.

The most important morphological peculiarity is undoubtedly the very remarkable
condition of the branchial sac, which is found in all the species of Culeolus {e.g., PL
VIII. fig. 3), in Fungulus ctnereus (PL XIII. fig. 9), and in the curious little species
Bathyoncus mirabilis (PL XXIV. fig. 9.) one of the Styelinas, but also a deep-water
form. It is quite distinct from the branchial sac in any other known Simple Ascidians,
and it is interesting to find it present in a member of a different sub-family. This
peculiar and simple structure, in which stigmata are apparently not formed, in consequence
of the suppression of the fine interstigmatic vessels, at first naturally suggests the
simple mesh-work found in Pyrosoma; but I am inclined to believe that the true structure
of the sac in that genus is a double row of laterally placed stigmata, running transversely
in place of longitudinally, and crossed at right angles by the internal longitudinal Inns.
In this case the branchial sac of Pyrosoma shows a simplified state of the condition found
in Boltenia elegans,2 where the stigmata are transverse (PL VII. fig. 2.), and is entirely
different from the branchial sac of Culeolus. Consequently, lam not of opinion that the
simple form of sac seen in Culeolus, Fungulus and Bathyoncus is a primitive form which
has survived, but think, on the contrary, that it is an after modification of a more compli-
cated type, which has probably taken place independently in the Bolteninaa and Styelinae,
and after the separation of these two groups by the development of compound tentacles

i And Culeolus murrayi, and the new species from Station 241.

2 I very much doubt even this being the survival of a primitive character, as Boltenia is certainly a highl) modified
form.

27*

THE VOYAGE OF H.M.S. CHALLENGER.

in the former. I incline to this view since it permits us to place in close relationship all
the pedunculated forms, whether possessing an ordinary or a modified branchial sac, and
does not necessitate the independent origin, in two distinct groups, of two sets of very
different characters, namely, compound tentacles and a peduncle, but merely of one — the
modification of the branchial sac. And this modification has probably taken place after
the separation of the Bolteninae from the Cynthinse (both these groups have arisen from
the StyelinaB previously), because we do not find any traces of the modified branchial sac
among the Cynthinse. The following scheme shows what I imagine to have been the
sequence of these stages in the evolution of the Cynthiidaj : —

Branchial sac not folded.
Tentacles simple.
No peduncle.

B. Branchial sac folded.

I
(Cynthiid^e).

Ascidia.
Ciona, $c.

(Styelin^e).

Styela.
Polyearpa.

C. Tentacles compound.

(Cynthinj;).

E. Branchial sac
modified.

I

Bathyoncus.

D. Peduncle.

I
(Boltexix^e).

Cynthia.
Microcosmus.

E'. Branchial sac
modified.

I
Culeolus.

Fungulus.

Boltenia.

The whole family seems to have sprung originally from a simple sessile form (marked
A. in the scheme), with the branchial sac not folded, and unbranched tentacles, of which the
present Ascidia, or more probably Ciona, is the comparatively little modified descendant.
From such a form the ancestral branch of the Cynthiidas would be first distinguished by a
longitudinal folding of the branchial sac, a condition which we find common to the three
sub-families. This hypothetical form (B. in the scheme) had still simple tentacles, and is
represented at the present day by the Styelinse. From this bne the Cynthinse and
Boltenime were later distinguished by the tentacles having become branched in their
common ancestor (C. in the scheme), and we find the comparatively slightly modified
descendants of this form in the Cynthia and Microcosmus of the present day. The next
stage in differentiation was the formation of a peduncle in the ancestral form of the Bol-
tenina3 (D. in the scheme), represented now by Boltenia. Hence the Bolteninae have been

REPORT ON THE TUNICATA. 279

separated off from the Cynthinse, since the latter group became distinct from the Styclinaa
through the development of compound tentacles. Next comes the modification of the
branchial sac, a change consisting in the suppression of the interstigmatic vessels, which
appears to have taken place in the Styelinae and the Bolteninse independently, and
resulting in the evolution of two forms (E. and E'. in the scheme), which were tin-
ancestors of Bathyoncus on the one hand and of Culeolus and Finujuhis on the other.

The above is what seems to me the simplest and most natural method of accounting
for the structural relations of the present genera, the only difficulty being the independent
origin of the modified branchial sac in two distinct groups. And the difficulty is increased,
since it is not evident what is the advantage of the structure seen in Culeolus, or what is
the reason of the modification. The idea that that structure is possibly better suited to
certain conditions consequent upon living at great depths is probably not correct, since
we find other Simple Ascidians, from as great or greater depths, having the normal struc-
ture of branchial sac, such as Abyssascidia ivyvillii, Corynascidia sidirni, Sty el a squamosa,
and Styela bythia, although it is true these forms are, according to my phvlogenetic
scheme (page 286), all less highly developed than at least Culeolus and Fungvlus, and
probably than Bathyoncus also.

A very notable feature in Culeolus is the condition of the blood-vessels in the test in
some of the species {e.g., Culeolus murrayi). This structure, when I first saw it in section
(PL VIII. fig. 2), at once suggested to my mind the idea that it was an accessory res-
piratory apparatus, and I still incline to that view. It is not difficult to imagine how the
blood-vessels in the test might, especially if the supply was not abundant, become branched
in the superficial layers of the organs, and swollen in their end twigs, in order that the blood
circulating in the test might thus receive a little additional aeration, and in this way the
large blood- vesicles and hollow papillae of Culeolus murrayi could be explained. Possibly
the enlarged terminations of the vessels seen in the tests of so many other Ascidians may
not only be the same structure in a less developed condition, but may also perform the
same function in a slighter degree. A glance at the diagram of the circulation in a
Simple Ascidian (page 280), will show that when the heart contracts ventro-dorsally
the test receives almost pure blood, but that when, on the other hand, it contracts dorso-
ventrally the blood carried to the test is impure blood, which has been returned from the
viscera, and is on its way to the branchial sac. From a consideration of this arrangement,
it is obvious how advantageous it would be for the Ascidian if the test could act, even
to a slight degree, as an accessory respiratory organ, and could allow the blood circulating
in its superficial layers to be brought into such close relation with the external medium
as to render possible a certain amount of oxydation.

In those forms where the terminal twigs of the blood-vessels are prolonged into
delicate processes of the test, these hair-like structures have generally acquired a second
function — that of attaching to their surfaces sand grains, small stones, shell fragments, and

280

THE VOYAGE OF H.M.S. CHALLENGER.

tv..

Fig. 23. — Diagrammatic longitudinal section of Ascidia, showing the heart, the blood-vessels, the branchial sac,
the alimentary canal, &c. , from the left side.

.si., branchial siphon ; at. si., atrial siphon ; t., test ; TO., mantle ; br.s., branchial sac ; p.br., peribronchial cavity ; cl., cloaca ; n.g.,
nerve ganglion ; In., tentacle ; gl., neural gland ; ce.a., oesophageal aperture ; St., stomach ; i., intestine ; r., rectum ; a., anus ; cm.,
genital organs ; g.d., genital ducts ; h., heart; c.sp., cardio-splanchnic vessel ; v.t., vessel to the test; t.k., terminal knob on vessel
in test ; v.t!., vessel from the test ; v. St., vessel to the stomach, &c. ; v.m., vessel to the mantle ; v.m!., vessel from the mantle •, d.v.,
dorsal vessel ; tr., transverse vessel of branchial sac; l.v., fine longitudinal vessel of branchial sac ; «</., stigmata of branchial sac ;
v.v., ventral vessel ; br.c, branchio-cardiac vessel ; sp.br., splanchno-branchial vessel.

REPORT ON THE TTJNICATA. 281

other foreign bodies, so as to form a continuous, more or less solid, protecting, and
concealing coat. This property is characteristic of the Molgulidae, hut we find it more
rarely, though just as well developed, in other families, as, for example, in the case of
Polycarpa molguloides (PI. XXII. fig. 5) in the Cynthiidae, and Ascidia conchilega in
the Ascidiidae.

In other cases, again, we find the protective covering of sand adhering directly to the
test, no hair-like processes having been developed. Under these circumstances, the coat ing
is usually more or less imperfect, and rarely attains any great thickness ; in Polycarpa
tinctor (PI. XXI. figs. 1-3), however, there is a complete layer of sand over the outer
surface of the test.

Calcareous spicules are present in the internal tissues of two genera of Simple Ascidians,
viz., Culeolus and Cynthia, and in each case they are found in several species of the
genus. They are, however, very different in their character in the two genera, being
irregularly branched, and with smooth surfaces in Culeolus (Plates VIII. to XIII.),
while they are simply rod-shaped or fusiform in Cynthia, but have their surfaces minutely
echinated (Plate XVII.).

In Culeolus they are present in all the species except Culeolus perlucidus, chiefly in
the walls of the endostyle and the branchial sac, but also in the tentacles, the dorsal
lamina, and other organs. But though varying in details, such as size, stoutness, number,
and length of branches, &c, according to the species and organ, still they have throughout
the genus, wherever found, a very great similarity. They have a characteristic appearance
which is difficult to describe, but which seems to depend upon their irregular, but
rather graceful, mode of branching, their invariably rounded angles and curved ends,
and lastly, upon the system of concentric markings, like contour lines, in their interior
(PI. VIII. fig. 6).

In the genus Cynthia, on the other hand, the calcareous spicules have a totally different
appearance. They have been found in three species, namely, Cynthia pallida, Heller,
where they were first discovered, Cynthia convplanata, Herdman, and Cynthia
papietensis, n. sp., and they occur in the test and the mantle, but especially in the
vessels of the branchial sac.

Just as in the case of the spicules of Culeolus, so also in Cynthia, the spicules, though
differing in various details according to the species and the part of the body in which
they are found, still have throughout a very characteristic appearance. They are always
elongated in shape, sometimes cylindrical, often more or less fusiform, but they are never
branched (PI. XVII. figs. 3, 8, 13, 15, and 19). The outer surface is always orna-
mented with usually closely-placed transverse rows of very minute spine-like processes,
which give a most characteristic appearance to the spicule, and render it very easily
recognisable in any tissue (PI. XVII. figs. 5, 6, and 20).

In all cases, in both Culeolus and CynlJii", these spicules appear to be formed in the

•_N-_> THE VOYAGE OF H.M.S. CHALLENGER.

connective tissue part of the mantle, branchial sac, or other organ, and in one species,
Cynthia complanata, the spicules of the mantle are enclosed in very distinct membranous
sheaths (PI. XVII. figs. 4, 5, and 6), and curiously enough the sheaths of different spicules
are connected by continuations of their ends, so that the different spicules are united to
form a system of tube-like structures winding through the tissues of the mantle.

As to the function of these calcareous spicules, I am not prepared to make any definite
statement. The first idea which presents itself is naturally that they are for the purpose
of giving strength and support to the organs in which they are present ; and this is
probably the correct explanation in the case of Culeolus. In that genus, on account of
the large meshes, and the want of fine longitudinal bars, the branchial sac is singularly
weak and fragile ; and the presence of the large branched spicules in the chief vessels
(very frequently placed at their points of intersection, so as to extend into several and
strengthen their junction) must materially add to the firmness and solidity of the organ.

This, however, cannot apply in the case of Cynthia. There the branchial sac is as
strong as in most Simple Ascidians. And the species in which calcareous spicules have been
found seem to require support as little as any of the other species of the genus. Besides,
the spicules in Cynthia are, as has been pointed out above, very different in their
characters from those of Culeolus, and do not seem as if they would be nearly so suitable
for the purpose of strengthening a delicate organ. Consequently, I think it is probable
that they have a different function in this genus.

In the Styelinse, besides a number of new species belonging to the large genera Styela
and Polycarpa, a specimen from deep water was collected, which has necessitated the
formation of the new genus Bathyoncus. The chief structural peculiarity of this form,
namely, its much modified branchial sac, has already been discussed above in connection
with Fungulus and Culeolus.

Besides Bathyoncus mirabilis, the only deep-water Styelinse are two new species of
Styela — Styela bythia and Styela squamosa. The former of these has distinct languets
(PL XVIII. fig. 8) along the free edge of the dorsal lamina — which is usually a plain
membrane in the Styelinse — and the latter has only two well-marked folds upon each
side of the branchial sac ; but with the exception of these two points, Styela bythia and
Styela squamosa are fairly typical representatives of the otherwise shallow- water genus
Styela.

In one of the new species of Polycarpa, the inconspicuous Polycarpa minuta, small
rod-shaped calcareous spicules are present, scattered through the prolongation of
the connective tissue of the mantle, which forms the covering of the polycarp (PI.
XXII. fig. 4), but they do not seem to be present in any of the other organs of the body.

In the family Ascidiidaa, out of the four new genera formed for Challenger sjjecimens,
three, viz., Hypobythius, Corynascidia, and Abyssascidia are somewhat aberrant; while
the fourth, Pachycldcena, is closely allied to Ascidia. Corynascidia is undoubtedly

REPORT ON THE TUNICATA. 283

allied to Coretta, while Abyssascidia is a link between Corynascidia and Ascidia. Like

some of the other deep- water forms, — c.//., Hypobythius, Funynlns, and some of the species
of Cideolus, — Corynascidia has the body pedunculated, and the test is soft and fragile,
both in that genus and in Abyssascidia. The alimentary canal, also, in all these abyssal
forms is small relatively to the size of the branchial sac and of the body generally, while
the mantle and branchial sac are always delicate.

The stomach and intestine vary considerably throughout the Ascidiidse in theil
relation to the branchial sac, but it is possible to trace the passage of one form into the
other. The simplest and central arrangement seems to be that which prevails in the
genus Ciona, where the oesophagus continues the antero-postcrior line of the branchial
sac, and thus throws the stomach and the first part of the intestine behind the branchial
sac. In Ascidia and in Paclujchlama a change has been effected, probably by the
branchial sac having extended down on the right side of the stomach and intestine,
resulting in the arrangement shown in figure 22, page 202.

In Corella the relation is very different, and the conditions of affairs found in
Corynascidia and Abyssascidia are intermediate between that seen in Corella and the
primitive arrangement in Ciona. In Corynascidia the stomach and intestine, which
reach as far back as the posterior end of the branchial sac, but do not extend beyond it,
are situated along the dorsal edge of the sac, and, if anything, slightly on the right side
(PL XXV. fig. 2). This condition might be brought about in a Ciona, by making
the posterior end of the branchial sac extend down upon the ventral side of the stomach,
instead of upon the right side as in Ascidia. Then in Abyssascidia, where the stomach
and intestine are at the posterior end of the right side of the sac (PL XXVII. fig. 3),
the process commenced in Corynascidia has advanced still further, and the branchial sac
has extended posteriorly upon the left side, in place of the ventral edge. Finally, in
Corella (PL XXVI. fig. 3) we find the same relation as in Abyssascidia, but here the
stomach and intestine- are still more completely upon the right side of the sac, so as to
form a perfect contrast to the arrangement in Ascidia; and in this respect Corella
japonica seems more advanced than Corella pa. rail el o<j ran una, where the disposition of
the intestine is more like that seen in Abyssascidia.

It is more natural, I think, to attribute these changes to a posterior prolongation of
the branchial sac, the stomach and intestine remaining comparatively passive, than to
suppose that the arrangement found in Ciona has become modified into those in Ascidia
and Corella, by the stomach and intestine having moved up in the one case upon the
left side of the branchial sac, and in the other upon the right, while in Corynascidia
they have occupied the dorsal edge.

Ciona shows also the simplest arrangement in the structure of the branchial sac. In
most of the species of Ascidia, the complication described under the name of longitudinal
plication has been produced, while in Corella and some other forms the stigmata have

(ZOOL. CHALL. EXP. — PART XVII. — 1682.) K 3(

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

become spirally coiled, and both, these changes have been caused by modifications of the
fine interstigmatic vessels. The most abnormal form of branchial sac is that found in
the genus Hypobythius, where there are no internal longitudinal bars. I am inclined to
believe this to be a secondary modification, since we occasionally find in species of
Ascidia, and especially of Corella (PI. XXVI. fig. 8), places where the internal longi-
tudinal bars are irregular and partially absent.

The dorsal lamina is found in several different conditions in the Ascidiidse. Probably
the primitive state was a series of languets, which were outgrowths from the dorsal line
(A' the sac, corresponding to the connecting ducts arising from the transverse vessels.
This simple condition is found in Ciona, and several other genera, while in Ascidia and
Pachychlama the languets have become more or less completely united by a membrane,
the dorsal lamina proper, but still show traces of their original arrangement by projecting
in the form of transverse ribs and marginal teeth. The simpler condition of a series of
tapering languets is found constantly amongst the lowest family of Simple Ascidians, the
Qavelinidae, whde the more modified and probably much more efficient organ, the plain
lamina, prevails in the highest and most complex family, the Molgulidse. In the inter-
mediate families, the Ascidiidse and the Cynthiidse, both conditions and all the transition
stages by which the one graduates into the other are found.

Neither of the two previously known genera of the Ascidiidse in which the test is
remarkably modified, namely, Rhodosoma and Chelyosoma, were collected during the
Challenger expedition, but two of the new forms show notable peculiarities in the test,
Packychiama having it greatly thickened all over, while Hypobythius ealycodes, Moseley,
has a series of symmetrically placed nodular, cartilaginous thickenings in the otherwise
thiu and membranous test.

A few lines will suffice for the faindy Qavelinidae, as I shall leave the discussion of re-
production by gemmation for the second part of this Report ; and the affinities of the new
Challenger genus Ecteinascidia have already been fully discussed in the systematic part.
In this genus, and still more in Clavelina, all the organs are found in a simple condition,
not unlike that seen in Ciona among the Ascidiidse. In Clavelina internal longitudinal
liars are totally wanting, the stomach and intestine extend beyond the branchial sac, and
the dorsal lamina is in the form of lan°-uets.

Two of the species of Ecteinascidia (Ecteinascidia fusca and Ecteinascidia turbinata)
supply us with evidence as to the homology of the languets with the connecting ducts
of the branchial sac. In Ecteinascidia fusca the connecting ducts are broad and
triangular (PL XXXVI. fig. 8, c.d.), and the languets (PI. XXXVI. fig. 11, I.) are also
flattened and triangular, although of course longer, while a short distance at each side of
them, just at the right and left edge of the dorsal area of the sac, is a row of processes very
simdar in every way to the connecting ducts, but having no internal longitudinal bars
attached to their apices, which hang freely, like those of the languets (PI. XXXVI. fig. 11).

REPORT ON TFTE TUNICATA. •>.">

Then again, in Ecteinascidia turbinated, where the eonnecting ducts ;ire not expanded
and triangular (PI. XXXVI. fig. 3), the languets arc merely finger-like processes
(PL XXXVI. fig. G, /.), and running down the two sides of the d irsal area are a series of
processes, which are shaped exactly like the connecting ducts, but are free at their ends,
like the languets beside them (PL XXXVI. fig. 6). Hence, it seems to mc that there
can be little doubt that the languets, and therefore the ribs and teeth of the dorsal lamina,
correspond to the connecting ducts of the branchial sac, and not to the papilla,' of the
internal longitudinal bars.

In conclusion, I give a table (page 286), showing what seem to me to be the
genetic relationships between the different groups of the Ascidise Simplices. As this is
founded merely upon the anatomy of the adult forms, it is of course liable to contain
errors of detail, but the main lines are probably correct. The wisdom of attempting to
form a genealogical scheme out of such insufficient data, will, I doubt not, be cpuestioned
by some, but if of no further value, the table serves at least to show the connection in
some of the most important points of structure between the different genera.

The ancestral form of all the Simple Ascidians I imagine to have been something like
a Clavelina without a peduncle (A. in the table). That is to say, it had a body which was
elongated antero-posteriorly, so as to allow the stomach to lie behind the branchial sac ;
it had unbranched tentacles, and a simple branchial sac, with no folds and no internal
longitudinal bars; and finally, it had the power of reproducing by gemmation. From such
a form it is easy to derive Clavelina, by the change (shown at 1) of the posterior end of
the body into a peduncle. Before this took place, however, two series of forms must '
have split off from the main line: one of these, by a change (2) in the relations of the
branchial sac and the stomach, produced the genus Perophora, while the other, by
the development of internal longitudinal bars in the branchial sac, became a form (P>.)
which was probably the common ancestor of all the other Simple Ascidians, and which, by
the addition of a peduncle (3), attained the structure of Ecteinascidia.

After this point a change must have taken place in the main line, from B. onwards,
resulting in the loss of the power of reproducing by gemmation, as this quality is
possessed by none of the remaining groups ; and thus a form was produced, having all
the characters of the genus Ciona. This was the common ancestor of the AscidiidaB,
the Cynthiidse, and the Molgulidae, and, after the separation of a form (C.) having the
branchial sac folded, of the AscidnVke alone. From this central Oiona-]ike being,
Abyssascidia and Corella on the one hand, and PachychUma and Ascidia on the other,
may be derived, by changing the relations of the stomach to the branchial sac in a manner
which has been already described (page 283).

Eeturning to C, the common ancestor of the Cynthiidaa and MolgulidaB, we find it

1 This and other objectionably dogmatic words which occur in the following description an- merely used to avoid
circumlocution. As has been already Btated, I fully recognise the hypothetical nature el' these investigations.

l>si;

THE VOYAGE OF H.M.S. CHALLENGER.

must have been a form with no peduncle, simple tentacles, internal longitudinal bars and
folds in the branchial sac, with the stomach probably posterior, and having no power of
gemmation. Such a form is represented, probably with little change, by the genera
Stt/ela aud Polycarpa, while Bathyoncus has diverged at the point 7. Pelonaia, which
like Bathyoncus differs from the other Styelime in having the branchial sac modified, is
probably of comparatively -recent formation, as some of the species of Styela show
tendencies in the same direction, — i.e., towards the loss of the branchial folds. From the
main stem between C. and Styela, a form D. has branched off, which had compound ten-
tacles, and was the common ancestor of the Cynthinas, the Bolteninse, and the Molgulidse.

Phylogenetic Table of the Ascidi^e Simplices,

Ascopcra.
Molgula.

Clenicella,

Culcolua.
Fimgulus.

Eugyra.

No folds in
branchial sao,

10.

Boltcnia.

Branchial sac modified.

Cynthia.
9. Microcosmus.

Peduncle.

E. Stigmata

curved and

generally in

spirals.

Styela.
Polycarpa.

Bathyoncus.

D. Tentacles compound.

Branchial sac modified.
I 7.

Fachychl&na. Abyssascidia.
Aseidia. Corella.

Ciona.

Stomach on
left side.

C. Branchial sac folded. 6.
I

Stomach on
right side.

No reproduction

by gemmation. Ecicinascidia.

4.

PerqpAora.

Clavel.ina.

Peduncle. Stomach on
| 3. Peduncle, left side.

B. Internal longitudinal bars
iu the branchial sac.

A. Body not pedunculated :

branchial sac not folded, and

with no internal longitudinal bars ;

stomach posterior to branchial sac ;

tentacles simple.

A, B, C, D, aud E are hypothetical ancestral forms of large groups, while 1-10 are points where a change of strncture
is supposed to have taken place, resulting in the divergence of one or more genera from the main line.

REPORT ON THE TUNICATA. 287

The direct descendants of such a form arc probably the genera Cynthia and Micro-
cosmus, while from this stem two side branches have arisen, one (E.) resulting in the
ancestors of the family of the Molgulidse, and the other by the development of a peduncle
(8), leading to the Bolteninse, and especially to the genus Boltenia — Culeolus and
Fungulus heing comparatively recent modifications (9).

E. is a modified Cynthiad form, in which the interstigmatic vessels have heeonie curved
and probably spirally coiled, so that the branchial sac has the structure found in the
typical Molgulidse. The genus Eugyra has probably been formed by the divergence from
the mainline, between E. and Molgula, of a form (10) in which the folds in the branchial
sac had become rudimentary.

INDEX.

The figures in dark type indicate the page on which the genus or species is described.

Abyssascidia, Herdm., 31, 38, 46, 183, 184, 185, 186,
187, 188, 193, 266, 270, 282, 283.
wyvillii, Herdm., 188, 192, 194, 251,
256, 279 (PL xxvii).
Alder, 7, 26.

Alimentary canal, 45, 51, 283.
Alternation in circulation, 6, 51.
Amaroucium, 48, 51, 55.
Amoeboid larva, 59.
AnureUa, 9, 59, 67, 68.
Aperture, atrial, 31.

branchial, 31, 32.
Appendicularia, 7, 8, 40, 42, 48, 53.
Appendiculariidse, 31, 36, 40, 41, 51, 55.
Aristotle, 5.
Aseidia, Miiller, 67, 86, 189, 196, 233, 245.

Linn., 6, 35, 46, 49, 51, 54, 55, 60, 93, 125,
134, 135, 138, 141, 146, 149, 154, 167,
184, 185, 187, 193, 196, 221, 231, 234,
266, 284.
ampulloides, van Ben., 60.
aspersa, O. F. Mull., 199, 238.
atra, Lesueur, 210.
borealis, Sav., 245.
canina, O. F. MiilL, 234.
challengeri, n. sp., 201, 250, 251, 256 (PL

XXX.).

clavata, Pall., 245.

complanata, Fabr., 200.

compressa, 42.

conchilega, 281.

corrugata, O. F. Mull., 234.

cylindracea, Herdm., 216, 252, 257 (PL

xxxiii. figs. 7-9).
depressa, Alder, 125, 199.
despecta, Herdm., 218, 251, 256 (PI. xxxiii.

figs. 10-12).

Aseidia falcigera, Herdm., 210, 211, 250, 255 (PL

xxxii. figs. 1-6).
fusifvrmis, Herdm., 42.
intestinalis, Linn., 234.
invohda, Heller, 198.
lepadiformis, O. F. MiilL, 245.
longitubis, Heller, 198.
mammillata, Cuv., 31, 44.
mentula, 14, 46, 198, 200, 203, 204.
meridionalis, Herdm., 199, 200, 207, 254,

258, 259, 270 (PL xxxi. figs. 4-8).
mollis, Han., 213.

Yerrill, 213.
ni<jra, Sav., 198, 201, 210, 211, 249, 250,

255.
obliqua, 213.

papittosa, C. G. Cams, 133.
parallelogramma, O. F. MiilL, 189.
plan nt„, Herdm., 206, 251, 256 (PL xxxi.

tigs. 1-3).
pulchella, Alder, 234.
pyriformis, Herdm., 219, 252, 257 (PL xxxiv.

figs. 1-6).
scahra, 44.

styeloides, Traust., 199.
lenera, Herdm., 206, 213, 254, 258, 259, 270

(PL xxxii. iigs. 7-10).
tinctor, Q. and G., 170.
tmnslucida, Herdm., 210, 215, 251,256 (PL

xxxiii. figs. 1-6).
vasal"*,, Herdm., 205, 251, 256.
venosa, 38.

mrginea, O. F. MiilL, 31, 45, 50, 200, 215.
Ascidiacea, 25.
Ascidite Composite, 25, 28, 29, 31, 35, 39, 41, 42, 18,

49, 51, 55, 57.
Salpiformes, 25.

290

THE VOYAGE OF H.M.S. CHALLENGER.

Ascidiie Simplices, 25, 28, 38, 40, 42, 49, 57, 58.

Sociales, 28, 57.
Ascidiidas, 29, 31, 34, 35, 38, 41, 49, 50, 57, 58, 60,

84, 182, 187, 262, 269.
Ascidina?, 185.

Ascidiopsis, YerriU, 196, 200.
Ascidium, Easter, 5, 6, 197.
Ascopera, Herdm., 59, 60, 61, 75, 262, 275.

giganfea, Herdm., 45, 62, 66, 67, 70, 251,

256, 275, 276 (PI. i., PI. ii. figs. 1-4 ; PI.
iii. figs. 3-5).

pedunculate, Herdm., 62, 64, 65, 251, 256,
275 (PI. ii. fig. 5 ; PI. iii. figs. 1, 2).
Atria, 32, 39, 40.
Atrium, 39.
Audouin, 7.
Baster, 5, 197.

Bathyoncus,-n. gen., 129, 148, 149, 150, 165, 270, 282.
mirabilis, n. sp., 165, 250, 256, 266, 277
(PI. xxiv. figs. 8-12).
Bladder cells, 28.
Blood, 53.

Blood corpuscles, 53.
Blood-vessels, 29, 32, 52, 279.

Boltenia, Sav., 5, 6, 83, 84, 85, 86, 91, 134, 230, 265,
270.
bolteni, Linn., 90.
clavata, 90.
coarcta, Gould, 88.
elegans, Herdm., 86, 249, 255, 277 (PI. vii.

figs. 1-5).
gibbosa, Heller, 90.
legumen, Less., 88, 254, 258, 259.
ovifera, Sav., 86, 87.
pachydermatina, Herdm., 45, 84, 89, 252,

257, 267 (PL vii. figs. 6-S).
pedunculata, M.-Edw., 90.
perlata, Suhni, MS., 115, 117.

Bolteninre, 30, 41, 46, 83, 84, 128, 130, 148, 183, 262,

265, 270, 278.
Botryllidc-e, 25.
Botrylloides, 48.

BotryUus, 5, 6, 39, 41, 48, 51, 52, 53, 56.
Branchial sac, 31, 45, 51, 277, 283.

siphon, 32.
Brooks, 55.
Ciesira, 59, 148.

ficus, 60.

parasitica, 60.

7» llucida, 60.

Capillaries, 217.
Carus, C. G., 6, 134.
Chamisso, 6.
Chandelon, 49.

Chelyosoma, 7, 31, 34, 38, 183, 184, 185, 186, 284.
Chevreulius, 8.
Ciliated arcs, 36.

Ciona, Fleni., 31, 35, 38, 39, 46, 51, 57, 183, 184,
185, 197, 233, 237, 238, 240, 266, 270,
283, 284.
canina, O. F. Miill., 234.
fnscicularis, Han., 234.
flemingi, Herdm., 235, 237, 249, 255 (PI.

xxxiv. figs. 7-10).
intestinalis, Fleni., 234, 235, 237, 238.
savignyi, n. sp., 236, 253, 258 (PI. xxxv. figs.

' 1, 2).
tenella, Verrill, 234.
Circulation, direction of, 51.
Classification, 25.

Clavelina, Sav., 6, 31, 35, 46, 49, 51, 54, 55, 197, 231,
239, 240, 245, 266, 284.
enormis, Herdm., 247, 250, 255 (PL xxxv.

figs. 3-5).
lex>adiformis, 247.

oblonga, Herdm., 246, 248, 249, 255 (PL
xxxv. figs. 6-10).
Clavelinidse, 31, 35, 38, 41, 46, 57, 58, 182, 184, 234,

237, 239, 262, 266, 269, 284.
Cloaca, 39.
Connectives, 39.

Corella, 34, 38, 46, 51, 137, 1S3, 184, 185, 186, 187,
188, 189, 193, 195, 197, 234, 266, 270,
283.
eumyota, 190.
japonica, Herdm., 190, 192, 253, 258 (PL

xx vi.).
larvceformis, 190, 191.
minuta, 190, 191.
ovata, 190.

parallelogramma, 38, 190, 191, 192, 193,196,
283.
Corellinae, 185.

Corynascidia, 34, 38, 183, 184, 185, 186, 230, 266,
270, 282, 283.
svhmi, 186, 250, 254, 258, 279 (PL

XXV.)

Course of intestine, 283.
Crenella, 220.
Ctenkella, 9, 59, 61.

REPORT ON THE TUXICATA.

•J!M

Culeolus, Herdm., 31, 39, 46, 50, 53, 84, 85, 90, 127,

128, 129, 1GG, 180, 265, 270, 276, 279,

281.
Comparison of the species of, 120.
mosrh,/,; Herdm., 91, 117, 25-1,257,265,

277 (PL x. figs. 7-12; PI. xiii. figs. 3, 4).
murrayi, Herdm., 84, 91, 103, 104, 105,

106, 107, 108, 109, 110, 113, 114, 116,

117, 118, 253, 258, 265, 276, 277 (PI.

viii., PI. ix.)
perlatus, Suhm, 91, 115, 118, 119, 249, 255,

265, 277 (PI. xi. tigs. 8, 9 ; PL xiii. figs.

1,2).
perlucidus, Herdm., 84, 91,111, 120, 129,

250, 256, 277, 281 (PL xi. tigs. 10-14:

PL xii. figs. 8-12).
recumbem, Herdm., 91, 107, 111, 112, 113,

114, 116, 118, 120, 250,256, 277 (PL xi.

figs. 1-7 ; PL xii. figs. 1-7).
sitkmi, Herdm., 115, 117.
wyville-thomsoni, Herdm., 41, 76, 84, 91, Distoma, 35.

103, 107, 109, 252, 257, 265, 277 (IJL x. Distribution, Bathymetrieal, 267.

Cynthia papietensis, Herdm., 136, 143, 253, 258, 265,
281 (PL xvii. figs. 10-16).

r, rrueosa (?) Philippi, 155.
Cynthia.' Caesirae, Sav., 60.

Pandocias, Sav., 148.

Simplices, Sav., 134.

StyeJse, Sav., 148.
Cynthiidae, 29, 30, 34, 38, 41, 46, 49, 50, 53, 54, 57,
58, 75, 83, 124, 182, 183, 199, 262, 265,
269, 275, 276, 278.
Cynthime, 34, 41, 59, 83, 84, 85, 127, 130, 148, 160,

I'll.', 265, 270, 278.
( 'ystingia, 85.
Dinih-iuliia, 148.
Diar.ona, 35, 238.
Didemnidae, 25.
Didemnum, 48, 51, 55.
Diplosoma, 8.
Diplosomidas, 25.
Distomidae, 25.

figs. 1-6 ; PL xiii. figs. 5. 6).
Cuvier, G.
Cynthia, M0IL, 81.

Sav., 6, 54, 58, 83, 130, 131, 134, 148, 1 10,

150, 167, 180, 197, 265, 281.
Thompson, 135.
arenosa, Herdm., 136, 140, 252, 257 (PL

xvi. figs. 6-9).
cerebriformis, Herdm., 130, 136, 252, 257

(PL xv. figs. 5-7).
complanata, Herdm., 135, 136, 143, 145, 172.

252, 257, 281, 282 (PL xvii. tigs. 1-9).
dione, Sav., 6, 60.
Jura, Heller, 138, 161.
fissa, Herdm., 136, 137, 251, 256 (PL xv.

figs. 8-11).
formosa, Herdm., 135, 136, 139, 252, 257

(PL xvi. figs. 1-5).
gigantea, Cunningham, 69. 70.
grandis, Heller, 34, 84, 135.
gregaria, Lesson, 73.
I, is,, Ida, Herdm., 135, 136, 146, 251, 256

(PL xv. figs. 1-4).
irregularis, Herdm., 45, 136, 138, 141, 252,

257 (PL xvi. figs. 10-12).
pallida, Heller, 136, 143, 144, 145, 146,

250, 252, 255, 257, 281 (PL xvii. figs.

17-21).

(ZOOL. CHALL. EXP. — PART XVII. — 1882.)

Geographical, 249.
Doliolidaa, 25.

Doliolum, 7, 8, 28, 31, 36, 39, 42, 43, 49, 55.
d. nticidatiiin, 36.
miilleri, 36.
Dorsal lamina, 38, 284.

tubercle, 44, 45, 276.
Edi inmndia, Herdm., 46, 234, 238, 239, 246, 266,
284.
erassa, Herdm., 240, 244, 253, 257,

269 (PL xxxvi. figs. 12-14).
fusca, Herdm., 240, 241, 244, 253, 258,

284 (PL xxxvi. tigs. 7-11).
turbinata, Herdm, 240. 243, 24i'. 255,
266, 284, 285 (PL xxxvi. figs. 1-6).
Endocarps, 168.
Endostyle, 36.

Eugyra, A. and H, 34, 53, 59, 60,61, 81, 262.
■a, Alder, 82.

g/nl„,-a, I [.Mi., 82.

tinans, Mull., 82.
kergudemensis, Herdm., 44, 81, 251, 256, 276
(PI. vi. tigs. 4-9).
. Wnill, 82.
FoL, 10, 37, 51, 55.
Fungulus, n. gen., 85, 127, 166, 27", 276.

n. sp., 127, 250,256, 265, 277 (PI.
xiii. figs. 7-10).

l; 38

292

THE VOYAGE OF H.M.S. CHALLENGER.

( remmation, 55, 56, 57.
Genital organs, 53.
Glandula, Stimp., 59, 60.
Gymnocystis, Giard, 59, 60.

Hairs, 28, 58, 139, 147.
Halocynthia, Verrill, 134, 135.
Hancock, 26, 150.
Hasselt, van, 6.
" Haus," 28.
Heller, 10, 26, 155.
Hertwig, 0., 9.
Hertwig, R, 9, 26.
Huxley, 7, 49, 51.
Hypobranchial groove, 36.
Hypobythinse, 185.

Hypobyihius, Mos., 184, 185, 186, 227, 266, 282, 284.
calycodes, Mos., 2, 227, 228, 233, 253,

258 (PI. xxxvii. figs. 1-5).
moseleyi, n. sp., 227, 230, 231, 254,

259 (PI. xxxvii. figs. 6-9).
Hypophysial gland, 43.

Julin, 10, 27.

Kowalevsky, A., 8.

Krohn, 8.

Kuhl, 6.

Kupffer, 8, 26, 150.

Lacaze-Duthiers, H. de, 9, 26.

Lamarck, 6.

Langnets, 38, 39, 284.

Larvacea, 25.

Linnaeus, 6, 197.

Lithonephrya, Giard, 50, 59, GO.

Liver, 48, 49.

Liverpool Free Public Museum, 72, 155, 159, 245.

Macdonald, 8.

Mantle, 30, 39.

Mertens, 7.

Meshes, 33.

Microcosms, Heller, 32, 130, 135,142, 164, 265.

helleri, Herdm., 131, 133, 134, 252, 257

(PI. xiv. figs. 1-4).
polymorphus, Heller, 131, 132, 133, 136,

138, 251, 256 (PI. xiv. figs. 7, 8).
propinquus, Herdm., 132, 134,251, 256

(PI. xiv. figs. 5, 6).
Milne-Edwards, H, 7, 26.
Minute plication, 35, 200.

Molgula, Forbes, 9, 59, 60, 61, 67, 81, 166, 167, 172,
173, 178, 262, 269.
Kupffer, 67, 81.

Molgula ccepiformis, 53.

crystallina, M0IL, 59.

forbesi, Herdm., 78, 252, 257, 276 (PI. v.

figs. 8-11).
gigantea, Cunningham, 41, 68, 69, 254, 258,

276 (PL iv. figs. 1-4).
gregaria, Lesson, 60, 73, 254, 259 (PI. iv.

figs. 5-8).
horrida, Herdm., 76, 254, 259 (PI. v. figs.

4-7).
pedunculated, Herdm., 41, 74, 251, 256, 275

(PL v. figs. 1-3).
pyriformis, Herdm., 44, 68, 79, 83, 254,
259, 269, 275, 276 (PL vi. figs. 1-3).
Molgulidse, 30, 33, 34, 41, 46, 48, 49, 50, 52, 57, 58,

83, 84, 93, 123, 166, 182, 183, 199, 269.
Moseley, 2, 293.
Miiller, O. F, 6.
Muscular system, 30.
Nervous system, 41.
Neural gland, 43.
Nucleus, 48, 51.
Ocelli, 42.

Octacnemus bythius, Mos., 2.
<_)i/,vjil< lira, 7.
Olfactory tubercle, 44.
Otocyst, 42.

PachycMtma, Herdm., 46, 183, 184, 185, 186, 187,
221, 266, 270, 282, 283, 284.
gigantea, Herdm., 225, 250, 255 (PL
xxviii. figs. 6-11 ; PL xxix. fig. 10).
olesa, Herdm., 219, 223, 251, 256 (PL

xxviii. figs. 1-5).
oblonga, Herdm., 221, 224, 251, 256
(PL xxix. figs. 1-9).
Pallas, 5.

Pamhcia, 148, 149.
Papilla?, 33, 35.
Pelonaia, 7, 54, 148, 149, 150, 286.

corrugata, 30, 148.
Pera, 59, 60.

huxleyi, 60.
Peribronchial cavity, 39.
Pericardium, 50.
Pericoronal ridge, 36.
Peripharyngeal band, 32, 36.
Pcron, 6.
Perophora, 46, 49, 175, 238, 239, 246.

listeri, 7.
Phallusia, Sav., 6, 196, 197, 233.

KKPOKT ON Till: TIWM'ATA.

l'!.:;

Phattusia aira, 210.

mammillafa, Ctiv., 8.
nigra, Sav., 210.
Phallusiae Cionse, Sav., 233.
Pirenae, Sav., 233.
Simplices, Sav., 233.
Phylogenetic table, 286.
Pigment, 42, 53.
Pituitary body, 43.

Polycarpa, Heller, 54, 135, 149, 150, 167, 174, 2GG,
270.
irregularis, Herdm., 178, 253, 258 (PL

xxiii. figs. 7, 8).
longisiphonica, Herdm., 177, 252, 257 (PI.

xxiii. figs. 3-G).
minuta, Ilerdm., 171, 251, 25G (PI. xxii.

figs. 1-4).
molgulouhs, Herdm., 58, 167, 172, 251,

256, 281 (PI. xxii. 5-7).

pcdata, Herdm., 180, 182, 253, 258 (PL

xxiv. figs. 1, 2).
peduuculata, Heller, 182.
pildla, Herdm., 174, 250 (PL xxii. figs.

11-15).
quadrata, Herdm., 168, 173, 253, 257 (PL

xxii. figs. 8-10).
radicata, Herdm., 167, 181, 252, 257 (PL

xxiv. figs. 3-5).
rigida, Herdm., 175, 177, 251, 256 (PL

xxiii. figs. 1,2).
sulcata, Herdm., 167, 1G8, 179, 253, 258

(PL xxiii. figs. 9-1 3).
tinctor, Q. and G., 167, 168, 170, 252,

257, 281 (PL xxi. figs. 1-6).
variant, 30.

viridis, Herdm., 30, 167, 168, 252, 257
(PL xxi. figs. 7-14).
Polyclinidse, 25.
Position, 26.
Praebrancliial zone, 32.

Pgrosoma, 6, 7, 28, 31, 36, 39, 43, 48, 49, 51, 55, 277.
Pyrosomida3, 25, 41.
Renal organ, 49.

Ehodosoma, 8, 60, 184, 185, 18G, 284.
RJiopalcea, 46, 57, 238.

Salpa, 6, 7, 28, 31, 36, 39, 43, 49, 50, 51, 55.
Salp<e, 7, 55.
SalpidEB, 25.
Sand, 58.

Savigny, 6, 26, 150.
Sohalk, 6.

Schlo8ser, 5.
Schmidt, C, 7.

Sense organs, 42.
Sphincter, 30, 32.

Spicules, 29, 98, 143, 146, 281, 282.
Stigmata, 32.
St impson, 8.
Stolon, 28.

Styda, Hun., 149, 150, 167.

Styda, Mad., 7, 38, 54, 60, S3, 135, 138, 148, 149,
162, 166, 167, 168, 269, 270.
bythia, Herdm., 151, 153, 162, 251, 256,265,

279, 282 (PL xviii. figs. 1 and 6-8).
dava, Herdm., 158, 253, 258, 265 (PL xix.

figs. 9, 10).
convexa, Herdm., 155, 251, 256 (PL xix. figs.

3,4).
exigua, Herdm., 157, 252, 257 (PL xix. figs.

5,6).
flava, Herdm., 84, 151, 152, 160, 172, 174,

254, 259 (PL xx. figs. 1-6).
glans, Herdm., 162, 174, 254,259, 275 (PL xx.

figs. 10-13).
grandis, Herdm., 153, 251, 256 (PL xix.

1,2).
iifixcii/'iriii, van Pen., 34, 45, 84, 150, 171, 276.
gyrosa, Heller, 151, 155, 252, 257.
lactea, Herdm., 156, 251, 256 (PL xix.

7, 8).
oblonga, Herdm., 84, 151, 159, 172, 174, 254,

259, 275 (PL xx. figs. 7-9).
radicosa, n. sp, 163, 251, 256 (PL xxiv. figs.

6,7).
squamosa, Herdm., 152, 251, 256, 279, 2>2

(PL xviii. figs. 1-5).
(uberosa, 48.
Styelrase, 41, 60, 83, 85, 129, 130, 14S, 1S3, 262, 265,

270. 278.
Suhm, E. von Willemces, 117.
Tentacles, 32, 41.
Test, 28, 30, 31.
Tethyum, 5, 6.
Thaliacea, 1, 25, 41, 48.
Traustedt, 10, 27.
Typhlosole, 48.
Uric acid, 50.
I rochord, 31, 42.
Cssow, 9.

Vascular system, 50.
1 'ortia llu. Linn., S6.

EXPLANATION OF THE PLATES.

I am indebted to Professor Moseley for the drawings of Hypobijtlt'ws cahjiixlrs, from
which figures 1, 2 and 5 on Plate XXXVII. have been prepared. Figure 1 on Plate
XVIII. is taken from a careful drawing executed for Mr. Murray by Mr. George West.

With the exception of these four, all the figures have been lit In >u iaj >li< -< 1 by .Mr.
Frederick Huth, jun., from my own drawings, supplemented, in the case of a few of the
views of the external appearance, by the actual specimen represented.

It may be well to mention that some of the branchial sacs represented are " combina-
tion figures," formed of small portions from several different specimens pieced together.
It was necessary to adopt this plan, in order to show the various important points of
structure within the compass of a reasonably small figure.

With the exception of a few which are only slightly enlarged, all the magnified
figures were drawn as seen by one of the following combinations, and are marked in the
explanations with the number of the objective used : —

Hartnack, obj. 4, with medium ocular
Hartnack, obj. 5. ,, ,,

Hartnack, obj. 7, ,, ,,

Hartnack, obj. 10 (water immersion),
Zeiss, obj. TV (oil immersion), with ocular 4

x 50
x 180
x 330
x 750
x 950

LIST OF ABBREVIATIONS.

a.

the anus.

cap.

at.

the atrial aperture.

<■Ji.li. .

at. n.

the nerves arising from the atrial

end of the ganglion.

e.d.

at.t. .

atrial tentacles.

b.c.

the blood corpuscles.

d.l. .

hi.

the bladder cells in the test.

d.t.

hi:

the branchial aperture.

e.l.

h,:f. .

the longitudinal folds in the bran-

chial sac.

en.

hr.rt. .

the nerves arising from the bran-

.'■

chial end of the ganglion.

:/• • •

(zool.

CHALL. EXr. — TAUT XVII. 1SS2.)

the capillaries.

the central brown area in the endo-

style.
the connecting duct in the bran hial

sac.
the dorsal lamina.
the dorsal tubercle,
the external longitudinal vessels in

the branchial sac.
the end style,
fibres in the test,
the hermaphrodite genital mass.
R 39

•_".m;

THE VOYAGE OF H.M.S. CHALLENGER.

g.d.

<jl.it.

."■•-'■
g.v.
h.

h.i.
li.m.

/'.

i.e.

i.l.

i. v.
I.
I',
l.b.h.

l.v.

the genital ducts.

tho subneural gland.

the germinal spot in the ovum.

the germinal vesicle in the ovum.

the heart.

the hepatic tubules.

the horizontal membranes in the

branchial sac.
the intestine,
the intestinal coecum.
the internal longitudinal bars in the

branchial sac.
blood-vessel to the intestine,
the languets.
smaller languets.
the lateral brown bands in the endo-

style.
the fine longitudinal (or inter-

stigmatic) vessels in the branchial

sac.

m.

the mantle.

m.h.

the muscular bands in the mantle.

m./.

the muscular fibres in the branchial

sac.

mJi.

the meshes in the branchial sac.

mh.n. .

a narrow mesh in the branchial sac.

mh.w. .

a wide mesh in the branchial sac.

n.

the neural mass.

n.y. .

the nerve ganglion.

0.

a mature ovum.

(>'.

a young ovum.

o.d.

the oviduct.

OB.

the oesophagus.

ce.a.

the oesophageal aperture.

a.m.

the oblique membranes in the bran-

chial sac.

v.

the ovary.

P-

the papilla? on the internal longi-

tudinal bars of the branchial sac.

j/.

the small intermediate papillae.

p.c. .

a pigment corpuscle.

ped.

the peduncle.

ped.c. .

the cavity in the peduncle.

ped.v, .

the blood-vessels in the peduncle.

p.p. .

the peripharyngeal bands.

r.

the rectum.

r.o.

the renal organ.

sg.

srjx.

sp.
St.

ts.v.

t.

t.a.
t.e.
t.e.

t.1k

t.k'.

t.h.i:

t.m.

t.rn.c

in.

in., in".

tn.m.

t.p.

ti:

tr'., tr

trab.
tr.x.

t.i.
H.t'.

t.v.

V.

v.d.
n\ e.

w.l.

the radiating vessels (angular) in

the branchial sac.
the radiating vessels (interangularj

in the branchial sac.
suspensor or connective between

branchial sac and mantle,
the stigmata in the branchial sac.
the stigmatic or ciliated cells in the

branchial sac.
the spicules,
the stomach.

the spiral vessels in the branchial sac.
the test.

the translucent area in the endostyle.
the small cells in the test,
the terminal enlargement of a blood-
vessel in the test,
the terminal knob on vessels in the

test,
a modification of t.k.
cornified papilla on the test,
the matrix of the test.
a part of the test cornified.
a tentacle,
smaller tentacles,
the membrane on the branchial side

of the tentacle,
a papilla on the outer surface of the

test,
the transverse vessels in the bran-
chial sac.
smaller transverse vessels in the

branchial sac.
the brown trabecular in the peduncle,
extra wide transverse vessel in the

branchial sac.
a thickening of the test.
the same for the support of the

viscera.
a testicular vesicle.
a blood-vessel in the test,
the vas deferens,
the white (or clear) edge of the

endostyle.
the wide longitudinal vessel in the

branchial sac.
the praebranehial zone.

PLATE I.

PLATE I.

Ascopera gigantea, Herdman.

Fig. 1. Ascopera gigantea, from the left side ; three-fourths of the natural size.

Fig. 2. The neighbourhood of the oesophageal aperture, seen from the interior of tin
branchial sac, showing the aperture, the posterior end of the dorsal lamina,
and the (esophageal extremities of the fourteen branchial folds; natural size.

Fig. 3. Dissection to show the course of the alimentary canal, seen from the right side, and
exposed by the removal of the mantle and the branchial sac, showing the
oesophagus, stomach, intestine, rectum, genital gland, and part of the muscula-
ture of the left side of the mantle ; natural size.

M "Challenger."

/■;, i

Fur. 3.

r,, z.

tU.

W A Herimaa, del

tthgA

ASCOPERA G1GANTEA, Herdman.

F Huth, Li£h» E*n*

PLATE II.

PLATE II.

Figs. 1-4. Ascopera gigantea, Herdman.
Fig. 5. Ascopera pedunculata, Herdman.

Fig. 1. Part of the branchial sac of Ascopera gigantea, between two folds, seen from the
inner side, magnified, showing a. transverse vessel (tr.), two internal longi-
tudinal bars (i.l.), and the stigmatic network between (Hartn., obj. 4).

Fig. 1. A small portion of the last figure, greatly magnified, to show the ciliated cells
(sg.c.) lining the stigmata (Hartn., obj. 7).

Fig. :>. Squamous epithelial cells from the surface of a transverse vessel: much magnified
(Hartn., obj. 10).

Fig. 4. Part of a- section through the test of Ascopera gigantea, showing the stellate
cells and small bladder cells ; magnified (Hartn., obj. 5).

Fig. 5. Part of the branchial sae of Ascopera peduncidata, seen from the inside; magnified
(Hartn.. obj. 6).

The Voyage of HM.S "Challenger"

Tumcata.Pl II.

Fig. 5

s3

Fur Z

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Fig 1

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n

W.A.Herdma:

FIG? 1-4 A5C0PERA G 1 G A NTE A , RerdmarL FIG. 5 A5COPERA P E D U N C U LATA , Herdmar..

PLATE I

PLATE III.

Figs. 1 and 2. Ascopera pedunculata, Herdman.
Figs. 3-5. Ascopera gigantea, Herdman.

Fig. 1. Ascopera 'pedunculata, from the left side ; three-fourths of the natural size.

Fig. 2. The dorsal tubercle of Ascopera pedunculata ; enlarged.

Fig. 3. Part of the branchial sac of Ascopera gigantea, seen from the interior; enlarged,

showing a branchial fold (br.f.) and part of the intermediate area (mh.).
Fig. 4. Part of tin1 branchial sac of Ascopera gigantea, between two internal longitudinal

liars, to show an unusually simple and regular arrangement of the stigmata;

magnified (Hartn., obj. 4).
Fig. 5. The dorsal region of the anterior end of the branchial sac of Ascopera gigantea,

showing the dorsal tubercle, part of the tentacular circlet, the branchial folds,

dorsal lamina, &c ; natural size.

The Voyage of H M :. ' '■ ■

PI. III.

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tD%&-,<sa»ocvar,

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FIGS 1-2 ASCOPERA PEDUNCULATA, Herman. FIGS 3-5 ASCOPERA GIGANTEA, Herdman

PLATE IV.

PLATE IV.

Figs. 1-4. Molgula gigantea, Cunningham.
Figs. 5-8. Molgula gregaria, Lesson.

Fig. 1. Molgula gigantea, a small specimen, from the left side ; natural size.

Fig. 2. Part of the branchial sac of Molgula gigantea, from the inside, natural size, t<>

show the longitudinal folds (br.f.), and the distant transverse vessels (tr.).
Fig. 3. Part of the preceding figure, between two folds, greatly enlarged, to show the

infundibula and the stigmata (Hartn., obj. 4).
Fig. 4. Dorsal part of the branchial sac of Molgula gigantea, from the inside, natural size,

showing the dorsal tubercle, the peripharyngeal bands, part of the tentacular

circlet, the dorsal lamina, the oesophageal aperture, and part of the branchial

sac
Fig. 5. Molgula gregaria, a large specimen, from the dorsal edge of the right side :

natural size.
Fig. 6. Part of the branchial sac of Molgula gregaria, from the inside ; magnified (Hartn.,

obj. 4).
Fig. 7. Dissection of the viscera on the right side of the mantle in Molgula gregaria, from

the inside, showing the genital gland (g.), and the renal organ (''■".);

natural size.
Fig. 8. Part of a section through the test of Molgula gregaria, showing the large stellate

protoplasts (t.e. ), in some of which clear vacuoles have appeared : magnified

(Haitn.. obj. 7).

The Voyage of H.M.S:'Chalienger"
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FIG3 1-4 MOLGULA G1GANTEA, Cunningham FIG5 5-8 MOLGULA GREGARIA, Lesson.

PLATE V.

Figs. 1-3. Molgida pedunculata, Herdman.
Figs. 4-7. Molgula horrida, Herdman.
Figs. 8-11. Molgula forbesi, Herdman.

Fig. 1. Molgula 'pedunculata, from the left side and anterior end ; natural size.

Fig. 2. The same with the test removed, showing the siphons, the musculature of the

mantle, and the position of the nerve ganglion ; natural size.
Fig. 3. Part of the branchial sac of Molgula pedunculata, seen from the inside ; magni-
fied (Hartn., obj. 4).
Fig. 4. Molgula horrida, from the right side ; natural size.
Fig. 5. The same with the test removed, to show the funnel-like siphons, the musculature

of the mantle, and the position of the renal organ on the right side ; natural

size.
Fig. G. The dorsal tubercle, and part of the tentacular circlet of Molgula horrida, seen

from the inside ; enlarged.
Fig. 7. Part of the branchial sac of Molgula horrida, seen from the inside ; magnified

(Hartn., obj. 4)
Fig. 8. Molgula forbesi, from the right side ; natural size.
Fig. 9. The same with the test removed, seen from the left side, showing the position

of the alimentary canal and the genital gland ; natural size.
Fig. 10. Part of the branchial sac of Molgula forbesi, seen from the inside; magnified

(Hartn., obj. 4).
Fig 11. The dorsal tubercle and the peritubercular area of Molgida forbesi ; magnified

(Hartn., obj. 4).

The Voyage of H .M.S." Challenger':

Fu,.l.

;

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p.p.

Fuf.r

Fig. JO.

M

W A.Heramnr..ael.

FIGS 1-3 MOLGULA P E D U N C U L AT A , Kerdman FIG? 4-7 MOLCULA HCRRIDA, Herdmar.

FIG5 8-11 MOLGULA FORBES I, Herdman.

PLATE VI.

PLATE VI.

Figs. 1-3. Molgula pyriformis, Herdman.
Figs. 4-9. Eagyra kerguelenensis, Herdman.

Fig. 1. Molgula pyriformis, from the left side ; natural size.

Fig. 2. Part of the branchial sac, seen from the inside, showing two of the branchial folds,

and an interspace ; magnified (Hartn., obj. 4).
Fig. 3. The peritubercular area and dorsal tubercle ; magnified (Hartn., obj. 4).
Fig. 4. Eugyra kerguelenensis, from the right side ; natural size.
Fig. 5. Another specimen of the same species, from the right side ; natural size.
Fig. 6. Part of the tentacular circlet, magnified, showing the different orders of tentacles

(Hartn., obj. 4).
Fig. 7. Portion of one of the branched tentacles, to show the loose membrane (tn.m.)

upon the posterior surface ; much magnified (Hartn., obj. 5).
Fig. 8. Part of the branchial sac of Eugyra kerguelenensis, from the inside, showing a

complete mesh and an infundibulum ; magnified (Hartn., obj. 4).

Fig. 9. The peritubercular area and dorsal tubercle of Eugyra kerguelenensis, showing

the simple quadrangular aperture of the duct, from the inside ; magnified
(Hartn., obj. 4).

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PLATE VII.

PLATE VII.

Figs. 1-5. Boltenia elegant;, Herdman.

Figs. 6-8. Boltenia pachydermatina, Herdman.

Fio-. 1. Boltenia elegans, from the right side ; natural size.

Fig. 2. Part of the branchial sac of the same species, from the inside, showing parts of

two folds (br.f.), and the transversely placed stigmata in the interspace

(Hartn., obj. 4.)
Fig. 3. The peritubercular area and dorsal tubercle, from the inside ; natural size.
Fig. 4. Dissection of the left side of the body, to show the alimentary canal and genital

organs, from the right side ; natural size.
Fig. 5. The right side of the mantle, from the inside, showing the genital gland, and the

network of muscle bands ; natural size.
Fig. 6. Boltenia pachydermatina, a small specimen, from the right side ; natural size.
Fig. 7. Part of the branchial sac, from the inside ; magnified (Hartn., obj. 4).
Fig. 8. The surface of the dorsal tubercle ; much enlarged.

The Voyage of HIS "Challenger."

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PLATE VIII.

PLATE VIII

Ctdeolus murrayi, Herdman.
Fig. 1. Cvleolus murrayi, from the left side ; natural size.
Fig. 2. A section through the outer part of the test, to show the blood-vessels (v.), papillae

{t.p.), and enlarged knobs (t.k/) ; magnified (Hartn., obj. 4).
Fig. :J. Part of the branchial sac, from the inside, showing one of the branchial folds (br.f.) :

magnified (Hartn., obj. 4).
Fig. 4. Part of the endostyle, with the edges laid out flat ; slightly enlarged.
Fig. 5. Part of the endostyle, seen from the inside, showing the clear edges, the spicules,

and the central brown bands ; magnified (Hartn., obj. 4).
Fig. 6. A portion of one of the large branched spicules from the branchial sac. to show

the concentric lines ; greatly magnified (Hartn.. obj. 10).
Fig. 7. The dorsal part of the anterior end of the branchial sac, seen from the inside,

showing a large (tn.) and a small (tn.') tentacle, the peritubercular area, the

dorsal tubercle, the praebranchial zone, &c. ; slightly enlarged.
Fig. 8. Dissection, showing the alimentary canal from the oesophageal aperture («■"•)

onwards ; slightly enlarged.
Fig. 9. The terminations of the genital ducts ; magnified (Hartn., obj. 4).
Fig. 10. The genital glands of the right side ; natural size.
Fig. 11. Part of the last figure, more enlarged, showing the testis and the surrounding o\ a.

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PLATE IX.

PLATE IX.

Culeolus murrayi, Herdman.

Fig. 1. A transverse section through the peduncle of Culeolus murrayi; magnified

(Hartn., obj. 4).
Fig. 2. Part of a longitudinal section through the same peduncle ; magnified (Hartn., obj. 4).
Fig. 3. One of the hollow papillae from the outer surface of the test ; magnified

(Hartn., obj. 4).
Fig. 4. Blood corpuscles from the interior of a papilla ; much magnified (Hartn., obj. 7).
Fig. 5. Part of an internal longitudinal bar from the branchial sac ; much magnified

(Hartn., obj. 5).
Fig. 6. A small portion of the last figure more magnified (Hartn., obj. 7).
Fig. 7. Calcareous spicules from the thin layer of mantle covering the viscera on the left

side ; magnified (Hartn., obj. 4).
Fig. 8. Part of the same layer of mantle, more magnified, to show the epithelium

(Hartn., obj. 7).
Fig. 9. The wall of the heart ; much magnified (Hartn., obj. 7).
Fig. 10. A few of the fusiform muscle-cells from the last figure ; more enlarged

(Hartn., obj. 10).
Fig. 11. Part of the pericardial membrane, showing a spicule (sp.), and the polygonal

epithelium ; much magnified (Hartn., obj. 7).
Fig. 12. One of the smaller tentacles, showing spicules, blood corpuscles, &c. ; magnified

(Hartn., obj. 4).
Fig. 13. DetaUs of structure of a tentacle —

a. The tip of a tentacle ; much enlarged (Hartn., obj. 5).

b. and c. Parts of the epithelium of the surface of a tentacle ; much enlarged

(Hartn., obj. 7).

d. Surface view of the short columnar cells of the free (anterior) edge ; much

magnified (Hartn., obj. 7).

e. The same cells ; profile view.

Fig. 14. Part of the dorsal lamina, showing the languets ; enlarged.

Fig. 15. The neighbourhood of the nerve ganglion, showing also the dorsal tubercle

(d.t.) ; slightly enlarged.
Fig. 16. The structure of the ova ; magnified.

a. A mature ovum, showing the germinal vesicle (g.v.), and germinal spot (g.s.)

(Hartn., obj. 7).

b. A young ovum, with comparatively little \ltellus around the germinal

vesicle (Hartn , obj. 7).

c. The outer edge of the mature ovum, more enlarged, showing the capsule of

cubical epithelium (Hartn., obj. 7).
Fig. 17. The structure of the testis —

a. Clump of spermatic vesicles ; magnified (Hartn., obj. 4).

b. The end of a vesicle ; more enlarged (Hartn., obj. 7).

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PLATE X.

PLATE X.

Figs. 1-6. Culeolus icyville-thomsoni, Herdman.
Figs. 7-12. Culeolus moseleyi, Herdman.

Fig. 1. Culeolus wyville-thomsoni, from the left side ; natural size.

Fig. 2. The branchial aperture ; natural size-

Fig. 3. The atrial aperture ; natural size.

Fig. 4. A section through the test, to show the modifications of the blood-vessels ;
magnified (Hartn., obj. 4).

Fig. 5. Part of the branchial sac, from the inside, showing one of the branchial folds (brf.) ;
magnified (Hartn., obj. 4).

Fig. 6. The dorsal region of the anterior end of the branchial sac, showing the inside of
the branchial siphon, the tentacles, the prsebranchial zone, the peri-
pharyngeal baud, the peritubercular area, the dorsal tubercle, the languets,
and part of the branchial sac ; slightly enlarged.

Fig. 7. Culeolus mosdeyi, from the right side ; natural size.

Fig. 8. The branchial aperture ; natural size.

Fig. 9. The atrial aperture ; natural size.

Fig. 10. Part of the peduncle, showing the brown trabecular ; enlarged.

Fig. 11. Part of the branchial sac, from the inside, showing one of the branchial folds
(br.f.) ; magnified (Hartn., obj. 4).

Fig. 12. The dorsal tubercle and peritubercular area ; magnified (Hartn., obj. 4).

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PLATE XT.

PLATE XL

Figs. 1-7. Culeolus recumbens, Herdnian.

Figs. 8-9. Culeolus perlatus, Suhm.

Figs. 10-14. Culeolus perlucidus, Herdman.

Fig. 1. Culeolus recumbens, a specimen seen from the right side ; natural size.

Fig. 2. Another specimen, from the left side ; natural size.

Fig. 3. The branchial aperture of fig. 1 ; natural size.

Fig. 4. The atrial aperture of fig. 1 ; natural size.

Fig. 5. Part of the branchial sac, from the inside ; magnified (Hartn., obj. 4).

Fig. 6. The dorsal part of the anterior end of the branchial sac, showing the peri-
pharyngeal bands, the nerve ganglion, and the dorsal tubercle ; magnified
(Hartn., obj. 4).

Fig. 7. Dissection, showing the alimentary canal and the genitalia of both sides ; slightly
enlarged.

Fig. 8. Culeolus perlatus, from the left side ; natural size.

Fig. 9. Part of the branchial sac, from the inside, showing a fold (br.f.) ; magnified
(Hartn., obj. 4).

Fig. 10. Culeolus perlucidus, from the right side ; natural size.

Fig. 11. Part of the branchial sac, from the inside, showing two of the simple folds
(br.f.); magnified (Hartn., obj. 4).

Fig. 12. The dorsal part of the anterior end of the branchial sac, showing the peri-
tubercular area, the dorsal tubercle, the peripharyngeal bands, and the nerve
ganglion; magnified (Hartn., obj. 4).

Fig. 13. Outline of the alimentary canal and the genital glands ; slightly enlarged.

Fig. 14. Part of one of the genital masses cut to show the hollow interior and the ducts ;
somewhat enlarged.

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PLATE XII.

PLATE XII.

Figs. 1-7. Guleolus recumbens, Herdman.
Figs. 8-12. Ctileolus perlucidus, Herdman.

Fig. 1. A section through the test of Guleolus recumbens, showing foreign particles

imbedded in the outer part (left side of figure) ; magnified (Hartn., obj. 4).
Fig. 2. A transverse section through the peduncle of the same species, showing the

cavities (ped.c), and the imbedded foreign particles ; magnified (Hartn.,

obj. 4).
Fig. 3. Part of the branchial sac, from the inside, showing a fold (br. f.) ; magnified

(Hartn., obj. 4).
Fig. 4. Part of the endostyle, showing the clear edges, with spicules, and the central

opaque area ; magnified (Hartn., obj. 4).
Fig. 5. Columnar cells from the brown band of the endostyle ; much magnified (Hartn.,

obj. 7).
Fig. 6. The terminations of the genital ducts; magnified (Hartn., obj. 4).
Fig. 7. One of the genital glands, enlarged, showing the ducts.
Fig. 8. A section through the test of Culeolus perlucidus, showing the papillae on the

outer surface ; magnified (Hartn., obj. 4).
Fig. 9. Part of the endostyle, showing the clear edge (w.e.), and the central more

opaque area (e.b.a.) ; magnified (Hartn., obj. 4).
Fig. 10. Part of the circlet of tentacles, showing three orders (tn., tn'. and tn.") ; magnified

(Hartn., obj. 4).
Fig. 11. Part of a section through one of the genital glands, showing the spermatic

vesicles externally, and the ova internally ; magnified (Hartn., obj. 4).
Fig. 12. Part of the wall of the stomach, with the lining epithelium scraped off, showing

the branched hepatic (?) tubules, with enlarged ends ; much magnified

(Hartn., obj. 7).

The. Voyage of H.M.S"Challenger'.'

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PLATE XIII.

PLATE XIII.

Figs. 1 and 2. Culeolus perlatus, Suhm.
Figs. 3 and 4. Culeolus moseleyi, Herdman.
Figs. 5 and 6. Culeolus wyville-thomsoni, Herdman.
Figs. 7-10. Fungultis dnereus, n. sp.

Fig. 1. Part of the peduncle of Culeolus perlatus, showing the brown trabecular ;

enlarged.
Fig. 2. Part of the surface of the test, showing the papillae ; enlarged.
Fig. 3. Part of the endostyle of Culeolus moseleyi, showing the spicules (sp.), the clear

edges (w.e.), and the central opaque area ; magnified (Hartu., obj. 4).
Fig. 4. The nerve ganglion of Culeolus moseleyi, and the patch of spicules in the mantle

over it ; magnified (Hartn.. obj. 4).
Fig. 5. A small part of the branchial sac of Culeolus wyville-thomsoni, seen from the

outside ; magnified (Hartn., obj. 4).
Fig. (5. Part of the endostyle of Culeolus wyville-thomsoni, showing the clear edge (w.e.)

the calcareous spicules (sp.), and the central area of opaque brown bands ;

magnified (Hartn., obj. 4).
Fig. 7. Fungulus dnereus, from the right side ; natural size.
Fig. 8. The branchial aperture ; enlarged.
Fig. 9. Part of the branchial sac, seen from the inside, showing one of the branchial

folds (br.f.) ; magnified (Hartn., obj. 4).
Fig. 10. Part of the endostyle, showing the clear edges (w.e.), and the central opaque

area. The left side of the figure shows the sinuses injected with blood

corpuscles; magnified (Hartn., obj. 4).

The Voyage of H.M.S."Challenger."

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FIG? 5-6 CULEOLUS WYVILLE-THOMSONI, Herdman. FIGS 7-10 FUNGULUS C I N E.R E US, n sp.

PLATE XIV

PLATE XIV.

Figs. 1-4. Microcosmus helleri, Herdman.

Figs. 5 and 6. Microcosmus propingxias, Herdmau.

Figs. 7 and 8. Microcosmus pdlymorphus, Heller.

Fig. 1. Microcosmus helleri, from the left side ; natural size.

Fig. 2. Part of the branchial sac of the same, seen from the inside, to show the folds ;
natural size.

Fig. 3. Part of the branchial sac of the same, seen from the outside, to show the enor-
mous transverse vessel (tr. x.) ; magnified (Hartn., obj. 4).

Fig. 4. Part of the branchial sac of the same, seen from the inside ; magnified (Hartn.,
obj. 4).

Fig. 5. Microcosmus propinquus, from the left side ; natural size.

Fig. 0. Part of the branchial sac of the same, seen from the inside ; magnified (Hartn.,
obj. 4).

Fig. 7. Part of the branchial sac of Microcosmus polymorphus, seen from the inside, to
show the folds ; natural size.

Fig. 8. A portion of the same sac; magnified (Hartn., obj. 4).

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PLATE XV.

PLATE XV.

Figs. 1-4. Cynthia hispida, Herdman.
Figs. 5-7. Cynthia cerebriformis, Herdman.
Figs. 8-11. Oynthia flasa, Herdman,

Fig. 1. Cynthia hispida, a specimen from the left side ; natural size.

Fig. 2. A part of the branchial sac, seen from the inside, showing a fold (br.f.) ; magnified

(Hartn., obj. 4).
Fig. 3. Part of the dorsal lamina, showing the two series of languets (I. and //) ; magnified

(Hartn., obj. 4).
Fig. 4. The dorsal tubercle ; natural size and enlarged.
Fig. 5. Cynthia cerebriformis, a specimen from the right side ; natural size.
Fig. 6. A part of the branchial sac, seen from the inside, showing a fold (br.f.) ; magnified

(Hartn., obj. 4).
Fig. 7. The dorsal tubercle and part of the peritubercular area, &c. ; magnified (Hartn.,

obj. 4).
Fig. 8. Cynthia fissa, from the right side ; natural size.
Fig. 9. Part of the branchial sac of Cynthia fissa ; seen from the inside, and showing a

fold ; magnified (Hartn., obj. 4).
Fig. 10. The dorsal tubercle and the peritubercular area of Cynthia fissa; magnified

(Hartn., obj. 4).
Fig. 11. One of the tentacles of Cynthia fissa, showing the short papilla-like pinnae;

magnified (Hartn., obj. 4).

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FIG3 8-11 CYNTHIA FISSA, Kerdman.

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PLATE XVI.

PLATE XVI.

Figs. 1-5. Cynthia formosa, Herdman.
Figs. 6-9. Cynthia arenosa, Herdman.
Fi_-s. 10-12. Cynthia irregularis, Henlman.

Fig. 1. Cynthia /< - i, from the right side ; natural size.

Fig. 2. Part of the branchial sac of Cynthia formosa, seen from th- - : magnified

(Hartn., ob> 4).
Fig 3. A -mall portion of the branchial sac of Cynti seen from the inside,

showing an irregularity ; magnified (Hartn.. obj. 4 (.
Fig. 4. Part of the dorsal lamina of Cynthia formosa, showing the marginal languets (/.);

magnified (Hartn.. obj. 4).
Fi^r. 5. The dorsal region of the anterior end of the branchial sac. showing the dorsal

tubercle (d.t.), the peritubercular area, the preebranchial zone, and part of

the circlet of tentacles [tn. and tn.'.): magnified (Hartn., obj. 4).
Fig. 6. Cynthia i - \ a specimen seen from the right side ; natural size.

Fig. 7. Part of the branchial sac of Cyntl - . seen from the inside, and showing

two of the folds (brf.), two interspaces, and part of the dorsal lamina (1.) ;

magnified (Hartn., obj. 4).
_. 8. The dorsal tubercle and peritubercular area of Cynthia arenosa; magnified (Hartn.,

obj. 4).
Fig. 9. A small portion of the modified test lining the branchial siphon of Cynthia.

magnified (Hartn., obj. o).
Fig. 10. Cynthia irregularis, from the left side : natural size.
Fig. 11. Part of the branchial sac of Cynthia irreavla - n from the inside, and

showing a fold (br.f. <. and several irregular areas ; magnified (Hartn., obj. 4).
Fig. 12. The peritubercular area and dorsal tubercle of Cynthia irret '$; magnified

(Hartn., obj. 4).

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PLATE XVII.

PLATE XVII.

Figs. 1-9. Cynthia complanata, Herdman.
Figs. 10— 1G. Cynthia papietensis, n. sp.
Figs. 17-21. Cynthia pallida, Heller.

Fig. 1. Cynthia complanata, seen from the right side ; natural size.

Fig. 2. A small portion of the test of Cynthia complanata, showing the calcareous

spicules (sp.) ; magnified (Hartn., obj. 4).
Fig. 3. Some of the calcareous spicules from the test, enlarged to show the arrangement

of the echinations ; much magnified (Hartn., obj. 7).
Fig. 4. A small portion of the mantle, showing the musculature and the spicules ;

magnified (Hartn., obj. 4).
Fig. 5. Some of these calcareous spicules (sp.) enlarged, showing the membranous sheaths

connecting them ; much magnified (Hartn., obj. 7).
Fig. 6. Parts of these spicules and their sheaths ; still more magnified to show details

(Hartn., obj. 10).
Fig. 7. Part of the branchial sac, seen from the inside, showing two of the folds (br.f.)

and the interspace; magnified (Hartn., obj. 4).
Fig. 8. Two of the calcareous spicules from the branchial sac in the last figure ; much

magnified (Hartn., obj. 7).
Fig. 9. The dorsal tubercle of Cynthia complanata, showing the convoluted course of the

slit ; enlarged.
Fig. 10. A small specimen of Cynthia papiete7isis, seen from the right side ; natural size.
Fig. 11. A larger specimen of the same species, seen from the right side ; natural size.
Fig. 12. Part of the branchial sac of Cynthia papietensis, seen from the inside, showing a

fold (brf.), an interspace, part of the dorsal lamina (I.), the dorsal tubercle

(d.t.), and the peritubercular area; magnified (Hartn., obj. 4).
Fig. 13. Two of the calcareous spicules from the same branchial sac ; much magnified

(Hartn., obj. 7).
Fig. 14. Part of the test of Cynthia papietensis, showing the branched vessels (v.), termi-
nating in knobs (t.k), and the calcareous spicules (sp.) ; magnified (Hartn.,

obj. 4).
Fig. 15. Three of the calcareous spicules from the test in the last figure, much enlarged to

show the screw-nail appearance (Hartn., obj. 7).
Fig. 16. Part of the circle of tentacles in Cynthia papietensis, showing three orders, two

compound (tn. and tn'.), and one simple (tn".) ; magnified (Hartn., obj. 4).
Fig. 17. Part of the branchial sac of Cynthia pallida, seen from the inside; magnified

(Hartn., obj. 4).
Fig. 18. A small portion of the mantle of Cynthia pallida, showing the calcareous spicules

(sp.) ; magnified (Hartn., obj. 4).
Fig. 19. Some of these calcareous spicules, more enlarged (Hartn., obj. 7).
Fig. 20. A small portion of one of the spicules, still more enlarged, to show the arrange-
ment of the minute echinations (Hartn., obj. 10).
Fig. 21. Part of the dorsal lamina of Cynthia pallida, showing the languets (I.), and the

spicules (sp.) ; magnified (Hartn., obj. 4).

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PLATE Will.

PLATE XVIII.

Figs. 1-5. Sti/ela squamosa, Herdman.
Figs. 1 and 6-8. Styela bythia, Herdman.

Fig. 1. A black manganese nodule, to which are attached a Brachiopod and two species

of Styela. The upper specimen is Styela squamosa, the lower is Styela bythia ;

natural size. (From a drawing by Mr. George West.)
Fig. 2. Part of the branchial sac of Styela squamosa, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. Part of the circle of tentacles of Styela squamosa, showing two sizes (in. and tn.') ;

magnified (Hartn., obj. 4).
Fig. 4. Small portion of the branchial sac of Styela squamosa, showing a fold (br.f.),

seen from the inside ; magnified (Hartn., obj. 4).
Fig. 5. Another part of the branchial sac of Styela squamosa, seen from the inside, show-
ing a piece of the dorsal lamina (d.l.) ; magnified (Hartn., obj. 4).
Fig. 6. Part of the branchial sac of Styela bythia, seen from the inside, showing the

closely- placed and crumpled internal longitudinal bars (i.l.) ; magnified

(Hartn., obj. 4).
Fig. 7. A small portion of the last figure, much magnified, to show the wavy outline of

the stigmata (Hartn., obj. 5).
Fig. 8. Part of the dorsal lamina of Styela bythia, showing the languets (/.); magnified

(Hartn., obj. 4).

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FIG3 1-5 STYELA SQUAMOSA , HerdmaTi F I Gs 1 and 6 - 8 ST Y E L A BYTHIA, .

PLATE XIX.

PLATE XIX.

Figs. I and 2. Styela grandis, Herdman.
Figs. 3 and 4. Styda convexa, Herdman.
Figs. 5 and G. Styda exigua, Herdman.
Figs. 7 uud S. Styela lactea, Herdman.
Figs 9 and 10. Styela clava, Herdman.

Fig. 1. Styela grandis, a specimen seen from the left side ; natural size.

Fig. 2. Part of the branchial sac of Styela grandis, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. Styela convexa, seen from the left side ; natural size.
Fig. 4. Part of the branchial sac of Styela convexa, seen from the inside; magnified

(Hartn., obj. 4).
Fig. 5. Styela exigua, from the right side ; natural size.
Fig. 6. Part of the branchial sac of Styela exigua, showing a fold (br.f.), seen from the

inside ; magnified (Hartn., obj. 4).
Fig. 7. Styela lactea, a specimen from the right side ; natural size.
Fig. 8. Part of the branchial sac of Styela lactea, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 9. Two specimens of Styela clava ; natural size.
Fig. 10. Part of the branchial sac of Styela clava, seen from the inside ; magnified

(Hartn., obj. 4).

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FIG5 7 8 S. LACTEA. FIG5 9-10 S.CLAVA, Herdmaii

PLATE XX.

PLATE XX.

Figs. 1-6. Styela flava, Herdman.
Figs. 7-9. StyeJa dblonga, Herdman.
Figs. 10-13. Styela glans, Herdman.

Fig. 1. Styela fiava, from the dorsal edge ; natural size.

Fig. 2. A'sinall portion of the test of Styela Jlava,saxfa,ce view ; magnified (Hartn., obj. 4).
Fig. 3. A small portion of the mantle of StyeJa flam, .showing the musculature:
magnified (Hartn., obj. 4).
Part of the branchial sac of StyeJa flava, showing a fold (br.f.), seen from the

inside; magnified (Hartn., obj. 4).
A small part of the dorsal lamina, showing the denticulations and ribs ; magnified

(Hartn., obj. 4).
The dorsal region of the anterior end of the branchial sac, showing the dorsal
tubercle (d.t.), the peritubercular area, and part of the circle of tentacles
{tn., tu'. and tit".) ; magnified (Hartn., obj. 4).
Styela oblonga, from the right side ; natural size.

Part of the branchial sac of Styela oblonga, showing a fold (brf.), seen from the
inside ; magnified (Hartn., obj. 4).
Fig. 9. A small portion of the last figure, much enlarged, to show the stigmatic cells

(sg.c), and the muscular fibres (m.f.) (Zeiss., obj. }\).
Fig. 10. Styela glans, from the right side ; natural size.
Fig. 11. Part of the branchial sac of Stijela glans, seen from the inside; magnified

(Hartn., obj. 4).
Fig. 12. A small portion of the last figure ; much enlarged (Hartn., obj. 5).
Fig. 13. The posterior end of the ventral edge of the branchial sac, seen from the inside^
showing the posterior extremity of the endostyle, and its continuation round
the posterior end of the sac to join the end of the dorsal lamina ; magnified
(Hartn., obj. 4).

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PLATE XXL

PLATE XXI.

Figs. 1-6. Polycarpa tinctor, Quoy and Gaimard.
Figs. 7-14. Polycarpa viridis, Herdman.

Fig. 1. Polycarpa tinctor, a specimen from the left side ; natural size.

Fig. 2. Another specimen from the right side ; natural size.

Fig. 3. The anterior end of another specimen : natural size.

Fig. 4. Part of the branchial sac of Polycarpa tinctor, showing a fold (br.f.), seen from

the inside; magnified (Hartn., obj. 4).
Fig. 5. A small portion of the last figure ; more enlarged (Hartn., obj. 5).
Fig. 6. The dorsal end of the anterior extremity of the branchial sac, showing the dorsal

tubercle (d.t.), and part of the circle of tentacles (tn.) ; slightly enlarged.
Fig. 7. Polycarpa viridis, a specimen from the right side ; natural size.
Fig. 8. Another specimen, seen from the right side ; natural size.
Fig. 9. A small part of the test of Polycarpa viridis, showing the network of vessels (v.) ;

magnified (Hartn., obj. 4).
Fig. 10. Part of the branchial sac of Polycarpa viridis, showing a fold (br.f.), seen from

the inside ; magnified (Hartn., obj. 4).
Fig. 11. A small part of the last figure, more highly magnified, showing the arrangement

of the muscular bundles (Hartn., obj. 5).
Fig. 12. The dorsal tubercle (d.t.), the peritubercular area, and part of the circle of

tentacles (tn. and tn.'), of Polycarpa viridis; magnified (Hartn., obj. 4.)
Fig. 13. One of the " polycarps," showing the ovary and the oviduct (o.d.), and vas

deferens (v.d.) ; magnified (Hartn. obj. 4).
Fig. 14. A small portion of the testicular part of the polycarp, showing the testicular

vesicles (t.v.), and the vas deferens (v.d.) ; highly magnified (Hartn., obj. 5).

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FIG5 1-6 POLYCARPA TINCTOR, Quoy and Gaimard. FIG5 7-14 POLYCARPA VIRID1S, Herdman.

PLATE XXII,

PLATE XXII.

Figs. 1-4. Polycarpa minuta, Herdman.
Figs. 5-7. Polycarpa molguloides, Herdman.
Figs. 8-10. Polycarpa quadrata, Herdman.
Figs. 11-15. Polycarpa pilella, Herdman.

Fig. 1. Polycarpa minuta ; natural size.

Fig. 2. Part of the branchial sac of Polycarpa minuta, seen from the inside, showing a

fold (br.f.) ; magnified (Hartn., obj. 4).
Fig. 3. One of the "polycarps" of Polycarpa minuta ; enlarged.
Fig. 4. A small portion of the last figure, much magnified, showing the ova (o.) and the

calcareous spicules (sp.) (Zeiss, obj. ^).
Fig. 5. Polycarpa molguloides, a specimen of the natural size, showing the outer coating

of sand.
Fig. 6. Part of the branchial sac of Polycarpa molguloides, seen from the inside; magnified

(Hartn., obj. 4).
Fig. 7. Another small portion, showing the wide internal longitudinal bar (Hartn., obj. 4).
Fig. 8. Polycarpa quadrata, a specimen seen from the right side ; natural size.
Fig. 9. Part of the branchial sac of Polycarpa quadrata, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 10. A small portioh of the same branchial sac, more enlarged, showing the mode of

junction of the horizontal membrane (h.m.) with the longitudinal vessels

(l.v.) and the internal longitudinal bars (i.l.) (Hartn., obj. 5).
Fig. 11. A number of specimens of Polycarpa pilella ; natural size.
Fig. 12. A small portion of the branchial sac of Polycarpa pilella, showing a fold (br.f.),

and part of the dorsal lamina (d.l), seen from the inside ; magnified (Hartn.,

obj. 4).
Fig. 13. The dorsal part of the posterior end of the branchial siphon of Polycarpa pilella,

seen from the inside, showing the dorsal tubercle (d.t,), the neural mass

(gl.n.), part of the dorsal lamina (d.l.), the prajbranchial zone (2.), and part

of the circle of tentacles (tn. and tn.') ; magnified (Hartn. obj. 4).
Fig. 14. The dorsal tubercle from the last figure, enlarged to show the ciliated cells round

the aperture (Hartn., obj. 5).
Fig. 1 5. The alimentary canal of Polycarpa pilella, showing the oesophagus, stomach, and

intestine ; enlarged.

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FIG? 1-4 POLYCARPA M1NUTA, HerdmaTi .
FlGs 8-10 P. 9 U AD RAT A, Herman.

FIGS 5-7 P. MOLGULOtDES, Herdman
FIG* 11-15 P. PILELLA, Herdman.

PLATE XXIII.

PLATE XXIII.

Figs. 1 and 2. Polycarpa rigida, Herdman.
Figs. 3-6. Polycarpa lonyisiphonica, Herdman.
Figs. 7 and 8. Polycarpa irregularis, Herdman.
Figs. 9-13. Polycarpa sulcata, Herdman.

Fig. 1. Polycarpa rigida, a specimen seen from the left side ; natural size.

Fig. 2. Part of the branchial sac of Polycarpa rigida, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. Polycarpa longisiphonica, from the left side ; natural size.
Fig. 4. Part of the branchial sac of Polycarpa longisiphonica, seen from the inside ;

magnified (Hartn., obj. 4).
Fig. 5. The tip of one of the tentacles of Polycarpa longisip>honica, seen from the side ;

magnified (Hartn., obj. 5).
Fig. 6. The same, seen partly from the front ; magnified (Hartn., obj. 5).
Fig. 7. Polycarpa irregularis, a specimen seen from the right side ; natural size.
Fig. 8. Part of the branchial sac of Polycarpa in-egtdaris, seen from the inside ;

magnified (Hartn., obj. 4).
Fig. 9. Polycarpa sulcata, a specimen seen from the dorsal surface ; natural size.
Fig. 10. Another specimen, seen from the right side ; natural size.
Fig. 11. Part of the branchial sac of Polycarpa sulcata, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 12. A small portion of the last figure, more magnified, and showing muscular fibres

in the vessels (Hartn., obj. 7).
Fig. 13. Part of a section through the test of Polycarpa sulcata, showing the fibrous

matrix (t.m.), the vessels (v.), and the cavities and terminal knobs (t.k.),

containing blood corpuscles (Hartn., obj. 7).

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FIGS 1-2 POLYCARPA R1G1DA, Herdman.
F1GS 7-8 P. IRREGULARIS, Herdman

FIG3 3-6 P.LONGISIPHON1CA, Herdman
FIG5 9-13 P SULCATA, Herdman

PLATE XXIV.

PLATE XXIV.

Figs. 1 and 2. Polycarpa pedata, Herdman.
Figs. 3-5. Polycarpa radicata, Herdman.
Figs. 6 and 7. Styela radicosa, n. sp.
Figs. 8-12. Bathyoncus mirdbilis, n. sp.

Fig. 1. Polycarpa pedata, from the right side ; natural size.

Fig. 2. Part of the branchial sac of Polycarpa pedata, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. Polycarpa radicata, a specimen seen from the right side ; natural size.
Fit;. 4. Another specimen of the same species, from the left side ; natural size.
Fig. 5. Part of the branchial sac of Polycarpa radicata, showing a fold (br.f.), seen

from the inside ; magnified (Hartn., obj. 4).
Fig. 6. Styela radicosa, from the right side ; natural size.
Fig. 7. Part of the branchial sac of Styela radicosa, seen from the inside ; magnified

(Hartn., obj. 4).

Fig. 8. Bathyoncus mirdbilis, from the left side ; natural size.

Fig. 9. Part of the branchial sac of Bathyoncus mirdbilis, showing two of the simple folds

(br.f.), seen from the inside; magnified (Hartn., obj. 4).
Fig. 10. Part of the circle of tentacles of Bathyoncus mirdbilis ; magnified (Hartn., obj. 5).
Fig. 11. The dorsal tubercle (d.t.), and peritubercular area of Bathyoncus mirdbilis;

magnified (Hartn., obj. 4).
Fig. 12. Part of the wall of the cloaca in Bathyoncus mirdbilis, seen from the inside, and

showing the terminations of the oviduct (o.d.) and vas deferens (v.d.), and

part of tin1 two circles of atrial tentacles (at.t.) ; magnified (Hartn., obj. 5).

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FlGs6-7 STYELA RADICOSA, n. sp. FIG? 8-12 BATHYONCUS M 1 R A B I L I S , n. sp.

PLATE XXV.

PLATE XXV.

Corynascidia suhmi, n. sp.

Fig. 1. Corynascidia suhmi, from the right side ; natural size.

Fig. 2. A semi-diagrammatic figure of a dissection, from the right side, showing the rela-
tions of the viscera (stomach, intestine, genital gland, &c.) to the branchial sac;
natural size.

Fig. 3. The alimentary and reproductive viscera of Corynascidia suhmi, seen from the
ventral surface, showing the course of the intestine (i. and r.), and the position
of the genital gland (g.) on the stomach (st.) ; natural size.

Fig. 4. The dorsal tubercle ; magnified (Hartn., obj. 4).

Fig. 5. Part of the circle of tentacles, showing the two sizes (tn. and tn.') alternately
placed (Hartn., obj. 4).

Fig. 6. Part of the branchial sac of Corynascidia suhmi, seen from the inside ; magnified
(Hartn., obj. 4).

Fig. 7. Part of the dorsal lamina, showing the double series of languets (/.) ; magnified
(Hartn., obj. 4).

Fig. 8. Part of the dorsal lamina of another specimen, where the languets are longer, and
are of two sizes, placed alternately ; magnified (Hartn., obj. 4).

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PLATE XXVT.

PLATE XXVI.

Corella japonica, Herdman.
Fig. 1. Corella japonica, from the left side ; natural size.
Fig. 2. The same, with the test removed, seen from the left side, showing the musculature

of the mantle ; natural size.
Fig. 3. The same, from the right side, showing the alimentary canal, &c. ; natural size.
Fig. 4. Part of the branchial sac, seeu from the interior ; magnified (Hartn., obj. 4).
Fig. 5. A small portion of the branchial sac, seen from the outside ; much magnified

(Hartn., obj. 5).
Fig. 6. Part of the musculature of the mantle ; magnified (Hartn., obj. 4).
Fig. 7. Part of the dorsal lamina showing the languets (I.) ; enlarged.
Fig. 8. The condition of the internal longitudinal bars in some parts of the branchial sac ;

seen from the inside ; magnified (Hartn., obj. 4).
Fig. 9. The dorsal part of the anterior end of the branchial sac, showing the dorsal tubercle

(d.t.) and the tentacles (tn.) ; magnified (Hartn., obj. 4).

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CORELLA JAPON1CA, Iman.

PLATE XX VII.

PLATE XXVII.

Abysaasei-dia wyvillii, Herdmaii.

Fig. 1. Abyssascidia wyvillii, from the upper or dorsal surface ; natural size.

Fig. 2. The same, from the lower or ventral surface ; natural size.

Fig. 3. The same, with the test removed ; seen from the right side, showing the mantle.

with muscular bands, the alimentary canal, and the atrial siphon ; natural size.
Fig. 4. The same, from the left side, showing the muscular bands in the mantle and the

branchial siphon ; natural size.
The viscera, seen from the right side, showing the alimentary canal and the

genital mass ; enlarged.
The same, from the left side ; enlarged.

Part of the branchial sac, seen from the inside ; magnified (Hartn., obj. 5).
A small portion of the preceding figure ; greatly enlarged (Hartn., obj. 7).
Part of an internal longitudinal bar, from fig. 7, showing the junction with a

connecting duct (c.d.) ; greatly enlarged (Hartn., obj. 7).
Fig. 10. Epithelial cells from the surface of a horizontal membrane of the branchial sac ;

much magnified (Hartn., obj. 10).
Fig. 11. Part of the series of dorsal languets ; magnified (Hartn., obj. 4).
Fig. 1 2. Anterior extremity of the endostyle (en.), and part of the tentacular circlet (tn.) ;

magnified (Hartn.,- obj. 4).
Fig. 13. Another part of the tentacular circlet; magnified (Hartn., obj. 4).
Fig. 14. The dorsal tubercle and peripharyngeal bands; magnified (Hartn., obj. 4).
Fig. 15. The nerve ganglion; magnified (Hartn., obj. 4).
Fig. 16. Part of the edge of the genital mass, showing testicular vesicles (t.v.), and ova

(or.) ; magnified (Hartn., obj. 4).
Fig. 17. Some of the ova; much magnified (Hartn., obj. 7).
Fig. 18. Two testicular vesicles ; much magnified (Hartn., ol >j. 7).

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PLATE XXVIII.

PLATE XX VII I.

Figs. 1-5. Pachychlcena obesa, Herdmau.
Figs. 6-11. PacJiyehlcena gigantea, Herdmau.

Fig. 1. Pachychlcena obesa, from the dorsal edge and part of the right side ; the greater
part of the test has been removed ; natural size.

Fig. 2. Part of the branchial sac of Pachychlcena ooesa, seen from the interior; magnified
(Hartn., obj. 4).

Fig. 3. Part of the same branchial sac, seen from the exterior; magnified (Hartn., obj. 4).

Fig. 4. A small portion of the last figure ; more enlarged (Hartn., obj. 5).

Fig. ">. Part of the dorsal lamina ; magnified (Hartn., obj. 4).

Fio-. 6. Pachychlcena gigantea, from the left side ; natural size.

Fig. 7. Part of the branchial sac of Pachychlcena gigantea, seen from the interior; magnified
(Hartn., obj. 4).

Fig. 8. Part of the branchial sac, seen from the exterior, showing the external wide-
meshed network, &c. ; magnified (Hartn., obj. 4).

Fig. i). The interior of the branchial siphon, showing the tentacles and the strong
muscular ring ; natural size.

Fig. 10. The dorsal tubercle, peripharyngeal band, peritubercular area, and tentacles ;
slightly enlarged.

Fig. 11. Part of the dorsal lamina of Pachychlcena gigantea ; very slightly enlarged.

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PLATE XXIX.

PLATE XXIX.

Figs. 1—9. PachycJilama ohlonga, Herdman.
Fig. 10. Pachychlcena gigantea, Herdman.

Fig. 1. Pachychlcena oblonga, from the right side ; natural size.

Fig. 2. The same, from the ventral edge ; natural size.

Fig. 3. A small portion of a section through the peripheral layer of test, showing the

terminal knobs of the blood-vessels, the pigment cells, &c. ; magnified (Hartn.,

obj. 4).
Fig. 4. Part of the branchial sac of Pachychlcena oblonga, seen from the interior; magnified

(Hartn., obj. 4).
Fig. 5. A small portion of the last figure ; more enlarged (Hartn., obj. 5).
Fig. 6. A small portion of the same branchial sac, showing a papilla edge-ways, an internal

longitudinal vessel, a connecting duct, and a transverse vessel ; much magnified

(Hartn., obj. 5).
big. 7. A part of the dorsal lamina; magnified (Hartn., obj. 4).
Fig. 8. The dorsal part of the anterior end of the branchial sac of Pachychlcena oblonga,

showing the dorsal tubercle, the peripharyngeal band, and the bases of the

tentacles ; magnified (Hartn., obj. 4).
Fig. 9. Part of the tentacular circlet of Pachychlcena oblonga ; magnified (Hartn., obj. 4).
Fig. 10. Terminal twigs of the blood-vessels in the test of Pachychlcena gigantea, show-
ing crystals attached to their outer walls (Hartn., obj. 7).

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FIG 10 P. G1GANTEA, Herdman.

PLATE \\\.

PLATE XXX.

Aseidia challengeri, n. sp.

Fig. 1. Aseidia challengeri, a large specimen, seen from the right side ; natural size.

Fig. 2. A much younger specimen, from the right side ; natural size.

Fig. 3. Part of a section through the test of Aseidia challengeri, showing vessels (r.)

1 "ladder cells (hi.), &c. ; magnified (Hartn., obj. 4).
Fig. 4. Part of the branchial sac, seen from the inside ; magnified (Hartn., obj. 4).
Fig. 5. Part of the dorsal lamina of Aseidia challengeri, seen from the left side; magnified

(Hartn., obj. 4).
Fig. 6. Another part of the same dorsal lamina, with a crenated and toothed edge, seen

from the left side ; magnified (Hartn., obj. 4).
Fig. 7. Another part of the same dorsal lamina, near the base, where it is wide and has

strongly marked ribs ; seen from the right side ; magnified (Hartn., obj. 4).
Fig. 8. The dorsal part of the anterior end of the branchial sac, showing the dorsal

tubercle (d.t.), the prjebranchial zone, with muscle bands («i.&.) showing

through, and two of the large tentacles (tn.) ; magnified (Hartn., obj. 5).

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ASCIDIA CHALLENGERI, n. sp.

PLATE XXXL

PLATE XXXI.

Figs. 1-3. Ascidia placenta, Herdinan.
Figs. 4-S. Ascidia meridionalis, Herdman.

Fig. 1. Ascidia placenta, seen from the right side ; natural size.

Fig. 2. Part of the branchial sac of Ascidia placenta, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. Part of the dorsal lamina of the same species ; magnified (Hartn., obj. 4).
Fig. 4. Ascidia meridionalis, seen from the right side ; natural size.
Fig. 5. Part of the branchial sac of Ascidia meridionalis, seen from the outside, and

showing the attachment of one of the "connectives" (.«.) to a transverse

vessel ; magnified (Hartn., obj. 4).
Fig. (3. Part of the same branchial sac, seen from the inside ; magnified (Hartn., obj. 4).
Fig. 7. Part of the dorsal lamina of Ascidia meridionalis; magnified (Hartn., obj. 4).
Fig. 8. The dorsal part of the anterior end of the same branchial sac, showing the dorsal

tubercle (d.t.), the prsebranchial zone with muscle bands showing through,

and three of the tentacl°<s one long (tn.) and two short (in/) ; magnified

(Hartn., ol>j. 4,.

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FIG5 1-3 ASCI DIA PLACENTA, Heraman. FIG5 4-8 ASC I D I A M E R I D I 0 N A L I S , Herman.

PLATE XXXII.

PLATE XXXII.

Figs. 1-6. Ascidia falcigera, Herdman.
Figs. 7-10. Ascidia tenera, Herdman.

Fig. 1. Ascidia falcigera, from the right side ; natural size.

Fig. 2. Another specimen of the same species, from the right side ; natural size.

Fig. 3. Part of the branchial sac of Ascidia falcigera, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 4. Part of the dorsal lamina of the same species ; magnified (Hartn., obj. 4).
Fig. 5. Part of the tentacular circlet; magnified (Hartn., obj. 4).
Fig. 6. The dorsal tubercle of Ascidia falcigera ; magnified (Hartn., obj. 4).
Fig. 7. Ascidia tenera, from the right side ; natural size.
Fig. 8. Part of the branchial sac of Ascidia tenera, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 9. Part of the dorsal lamina of the same species; magnified (Hartn., obj. 4).
Fig. 10. The dorsal tubercle and peripharyngeal band of Ascidia tenera ; magnified

(Hartn., obj. 4).

The Voyage of H M. S "Challenger"

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F!GS 1-6 ASCID1A FALC1GERA, Rerdman. FIG5 7-10 ASCIDIA TENERA, Herdman.

PLATE XXXIII,

PLATE XXXIII.

Figs, 1-6. Ascidia translucida, Herdman.
Figs. 7-9. Ascidia cylindracea, Herdman.
Figs. 10-12. Ascidia despecta, Herdman.

Fie. 1. Ascidia translucida, from the right .side : natural size.

Fig. 2. The same from the left side, showing the vascular ramifications in the test ;

natural size.
Fig. 3. Part of the branchial sac of Ascidia translucida, seen from the outside, and

showing "minute plication" ; magnified (Hartn., obj. 4).
Fig. 4. Part of the same branchial sac, seen from the inside ; magnified (Hartn., obj, 4).
Fig. 5. The tentacles and the dorsal tubercle, &c, of Ascidia translucida ; magnified

(Hartn., obj. 4).
Fig. (5. Part of the dorsal lamina of the same species ; magnified (Hartn., obj. 4).
Fig. 7. Ascidia cylindracea, from the right side ; natural size.
Fig. 8. Part of the branchial sac of Ascidia cylindracea, seen from the inside; magnified

(Hartn... obj. 4).
Fig. \). Part of the dorsal lamina of the same species, showing the sinuses engorged with

blood corpuscles; magnified.
Fig. 10. Ascidia despecta, from the right side ; natural size.
Fig. 11. Part of the branchial sac of Ascidia despecta, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 12. Part of the dorsal lamina of the same species ; magnified (Hartn., obj. 4).

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PLATE XXXIV

PLATE XXXIV.

Figs. 1-6. Ascidia pyriformis, Hirdman.
Figs. 7-10. Ciona flemingi, Herdman.

Fig. 1. Ascidia pyriformis, from the right side ; natural size.

Fig. 2. The same specimen from the left side ; natural size.

Fig. 3. Another specimen with the test removed, seen from the right side, showing the

shape of the body, the siphons, &c. ; natural size.
Fig. 4. Part of the branchial sac of Ascidia pyriformis, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 5. The dorsal tubercle of the same species ; magnified (Hartn., obj. 4).
Fig. 6. Part of the dorsal lamina of Ascidia pyriformis ; magnified (Hartn., obj. 4).
Fig. 7. Ciona flemingi, from the right side ; natural size.
Fig. 8. Part of the branchial sac of Ciona flemingi, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 9. Part of the series of dorsal languets of the same species ; magnified (Hartn., obj. 4).
Fig. 10. The dorsal tubercle of the same species: slightly enlarged.

The Voyage of H.M. ^'Challenger.'

(XXIV

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FIG5 1-6 ASCIDIA PYR1F0RMIS, Herdman. FIGS 7-10 CIONA FLEMINGI, Herdman

PLATE XXXV.

PLATE XXXV.

Figs. 1 and 2. Ciona savignyi, n. sp.
Figs. 3-5. Clavelina enormis, Herdman.
Figs. 6-10. Clavelina oblonga, Herdman.

Fig. 1. Ciona savignyi ; natural size.

Fig. 2. Part uf the branchial sac of Ciona savignyi, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. 3. A colony of Clavelina enormis; natural size.
Fig. 4. Part of the branchial sac of Clavelina enormis, seen from the inside ; magnified

(Hartn., obj 4).
Fig. 5. Part of the dorsal lamina of the same species, showing the large triangular

languets (/.) ; magnified (Hartn., obj. 4).
Fig. 6. A colony of Clavelina oblonga; natural size.
Fig. 7. Part of- the branchial sac of Clavelina oblonga, seen from the inside; magnified

(Hartn., obj 4).
Fig. 8. The dorsal part of the branchial sac of Clavelina oblonga, seen from the inside,

showing some of the languets (/.) ; magnified (Hartn., obj. 4).
Fig. 9. Part of the same branchial sac, seen from the inside; much magnified

(Hartn., obj. 5).
Fig. 10. Part of the tentacular circlet of Clavelina oblonga, showing large and small

tentacles; magnified (Hartn., obj. 4).

The Voyage of H.M.S"Challenger"

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FIG? 1-2 CIONA SAVIGNYI , i:.sp. , FIG5 3-5 CLAVELINA ENORMIS, Herdman.

FIG? 6-10 CLAVELINA OBLONGA, Herdn

PLATE XXXVI.

PLATE XXXVI.

Figs. 1-G. Edeinascidia turbinata, Herdman.
Figs. 7-11. Edeinascidia fusca, Herdman.
Figs. 12-14. Ecteinascidia crassa, Herdman.

Fig. 1. A large colony of Ecteinascidia turbinata ; natural size.
Fig. 2. Three individuals from the same colony, showing the stolons ; natural size.
Fig. 3. Part of the branchial sac of Ecteinascidia turbinata, seen from the inside; mag-
nified (Hartn., obj. 4).
Fig. 4. Part of the circle of tentacles of the same species, showing three sizes (///., tn.' and

tn.") ; magnified (Hartn., obj. 4).
Fig. 5. The viscera on the left side of the mantle in Ecteinascidia turbinata, showing the

relations of the genital glands ; slightly enlarged.
Fig G. The dorsal part of the branchial sac of the same species, seen from the inside.

showing the tentacular languets (/.) and the rudimentary connective ducts

(c.d.) ; magnified (Hartn., obj. 4).
Fig. 7. Ecteinascidia fusca, seen from the right side ; natural size.
Fig. 8. Part of the branchial sac of Ecteinascidia fusca, seen from the inside ; magnified

(Hartn., obj. 4).
Fig. !». A small part of the branchial sac of Ecteinascidia fusca; much enlarged

(Hartn., obj. 7).
Fig. 10. Part of the dorsal region of the anterior end of the same branchial sac, showing

the dorsal tubercle (d.t.), the prsebranchial zone, and three of the tentacles

(tu.) ; magnified (Hartn., obj. 4).
Fig. 11. Part of the dorsal region of the branchial sac of Ecteinascidia fusca, showing

the languets ; magnified (Hartn., obj. 4).
Fitr. 12. Ecteinascidia crassa ; natural size.
Fig. 13. Part of the branchial sac of Ecteinascidia crassa, seen from the inside ;

magnified (Hartn., obj. 4).
Fig. 14. The internal longitudinal liars (id.) and their connecting ducts (c.d.), from the

branchial sac of Ecteinascidia crassa; much enlarged (Hartn., obj. 5).

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FIG? 1-6 ECTE I N ASC I D I A T U R B I N AT A , Herdman. FIG? 7-11 E . F U S C A , H - :man.

FIG? 12-14- E.CRASSA, Herdman.

PLATE XXXVIT.

PLATE XXXVII.

$

Figs. 1-5. Hijpohythhis cahjcodes, Moseley.
Figs. 6-9. Hypobythius moseleyi, n. sp.

Fig. 1. Hypobythius cahjcodes, seen from the ventral surface, and showing the body and
peduncle, the cartilaginous thickenings of the test (t.t.), the branchial (br.)
and atrial (at.) apertures, and most of the internal organs ; half the natural
size. (From a drawing by Professor H. N. Moseley.)

Fig. 2. Outline of the dorsal side of the body of Hypobythius caly codes, to show the
atrial aperture (at.), and the symmetrical arrangement of the nodules of
thickened test (t.t.) ; much reduced. (From a drawing by Professor H. N.
Moseley.)

Fig. 3. A small portion of the mantle of the same species, to show the arrangement of
the muscle bands (m.b.) ; magnified (Hartn., obj. 4).

Fig. 4. Part of the branchial sac of Hypobythius calycodes, showing the rounded stigmata
(sg.) formed by the irregular vessels (ti\) ; magnified (Hartn., obj. 4).

Fig. 5. Two spermatozoa (one seen sideways) of Hypobyth his cahjcodes; much magnified.
(From a drawing by Professor H. N. Moseley.)

Fig. 6. Outline of the body of Hypobythius moseleyi; about the natural size.

Fig. 7. The dorsal part of the branchial sac of Hypobythius moseleyi, showing the stig-
mata (sg.), and the dorsal lamina (d.l.) ; magnified (Hartn., obj. 5).

Fig. 8. The dorsal region of the anterior end of the branchial sac of Hypobythius moseleyi ',
showing the dorsal tubercle (d.t.), the nerve ganglion (n.g.), the neural
gland (n.gl.) the peripharyngeal bands (p-P-), and the commencement of
the dorsal lamina (d.l.) ; much magnified (Hartn., obj. 5).

Fig. 9. Part of the mantle of Hypobythius moseleyi, showing the arrangement of the
muscle bands (rn.b.) ; magnified (Hartn., obj. 4).

The Voyage of H M Z ."Challenger"

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