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SIBOGAEXPEDITIE.

Siboga-Expeditie

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VERZAMELD IN

NEDERLANDSCH OOST-INDIË 1899— 1900

AAN BOORD H. M. SIBOGA ONDER COMMANDO VAN

Luitenant ter zee le kl. G. F. TYDEMAN

UITGEGEVEN DOOR

Dr. MAX WEBER

Prof. in Amsterdam, Leider der Expeditie

■

(met medewerking van de Maatschappij ter bevordering van het Natuurkundig
Onderzoek der Nederlandsche Koloniën)

BOEKHANDEL EN DRUKKERIJ

VOORHEEN

E. J. BRILL
LEIDEN

Siboga-Exp editie

XXXVIII

THE

SERGESTIDjE OF THE SIBOGA EXPEDITION

BY

H. J. HANSEN

Gjentofte (near Copenhagen)

With 5 plates and 14 text figures

-=S*-i®««§<=-

late E. J. BRILL

PUBLISHERS AND PRINTERS

LEIDEN — 1919

THE SERGESTID£ OF THE SIBOGA EXPEDITION

BY

H. J. HANSEN,

Gjentofte (near Copenhagen).

With 5 plates and 14 text figures.

This well defined and most interesting family has with good reason been divided into
two sub-families: Sergestinae and Luciferinse. The first sub-family comprises four genera:
Sergestes H. Milne-Edw., Petalidium Sp. Bate, Sicyonella Borradaile (Apkareocaris Calm.) and
Acetes H. Milne-Edw., while the genus Liicifer Vaughan Thomson {Leucifer H. M.-Edw.)
constitutes the Luciferinse. With exception of Petalidium all genera are represented in the
"Siboga" collection. Ot Sergestes, Sicyonella and Acetes the expedition has secured a good
material, containing some undescribed species, while the collection of Ltuifer is exceedingly rich.
The Zoological Museum in Copenhagen possesses of the genera in question a good material,
which in many cases has been most useful for comparison, and with the kind allowance of the
Editor of the "Siboga" work I have even been able to include in the present paper descriptions
with figures of forms — most of them from the Indo-Chinese seas — not gathered by the
"Siboga"' of the hitherto imperfectly known genus Acetes. As the degree of our knowledge of
the four genera is very different, it is found adequate to deal with each genus according to
the state of the literature.

In the treatment of the genera and species I have introduced a special study ot the male
copulatory organs on the first pair of pleopods, the petasma. Various authors have published
a more or less good outline of the petasma of a single form or of two species, but only one
author, S. J. Smith, has given a more detailed representation of the petasma in a single species
[Sergestes roèusttcs Smith), and nobody has attempted a comparative investigation in any of
the genera. As in the order Euphausiacea, the petasma has shown itself to afford as a rule
the best and most reliable specific characters; it is always very important, and in some cases
it is even absolutely necessary to possess an adult male in order to be able to determine a

SIBOGA-EXPED1T1E XXXVIII.

.'4832

species vvith absolute certainty, to separate it from a closely allied form taken in the same or
in another sea. Therefore I give a detailed representation of the petasma in every species. As
the organ is very complicate in the genus Sergestes, white it is more or less reduced in the other
genera, it will be expediënt to give a description of the petasma in the general treatment of the
genus named, and later on at each of the other genera to mention its reduction or structure.

I. Sub-Family Sergestin^;.
Sergestes H. Milne-Edw.

This genus was established in 1830 by H. Milne-Edwards (Ann. Sci. Natur. t. XIX,
1830) on a single species. Since that remote year numerous authors have published larger or
smaller contributions to our knowledge, but among them only some of the most important are
mentioned here. — In 1859 a valuable paper was published by Henrik Kröyer (Forsog til en
monographisk Fremstilling af Kraebsdyrslaegten Sergestes, in: K. D. Vidensk. Selsk. Skrifter, 5.
Reekke, naturv.-math. Afd., 4. B.), in which he described and figured on five plates 15 species,
all new, but the majority of them briefly characterized by him in a preliminary paper in 1855. —
In three papers published 1882 — 86 S. J. Smith gave excellent descriptions with good figures
of 3 species from the Atlantic. — In 1888 the great work by C. Spence Bate on Decapoda
Macrura (Rep. Voy. "Challenger", Zool., vol. XXIV) wasissued, in which a very large con-
tribution to our knowledge of Sergestes and its larval forms is found; the author established
in all 24 species of Sergestes as new. — Some years after I wrote a treatise on this genus
(On the Development and the Species of the Crustaceans of the genus Sergestes, in : Proc.
Zool. Soc. London, Dec. 1, 1896). It contains a review of the whole literature from 1830 to
1895 and an enumeration of all species, in all 59 (or, if the dead-born genus Sciacaris Bate is
included, 60 species) of the genus Sergestes. Furthermore it is proved that only about 20 of
these species have been established on adult animals, and that some of these species must be
cancelled as synonyms, while the remaining majority, nearly two scores of species, had been
founded on larval forms in the MastzgoJ>tts-sta.ges ; besides it was shown that some of the larvae
established as separate species are Mastigo/>its-stages of species already known as adults, while
other larvae belong to forms unknown in the adult stage. Finally, based on the literature and
on a rich material of adults and larvae of forms living- near the surface and belonging- to the
• Copenhagen Museum, I gave a view of all forms. — A later publication of mine (H. J. Hansen:
The Crustaceans of the genera Petalidiiim and Sergestes from the 'Challenger', with an account
of luminous organs in Sergestes challengeri n. sp., in: Proc. Zool. Soc. London, Jan. 20, 1903)
contains a critical revision of the "Challenger" material preserved in the British Museum (Natural
History); its most important point is the discovery of a large number of complex luminous
organs in a single form. — It is deemed unnecessary to enumerate here the numerous papers
published since 1895, which contain contributions on Sergestes \ some among them are quoted
on the following pages.

The copulatory organs, the pet as ma, much be dealt with at length. In 191 3
K. Stephensen (The copulatory Organ (Petasma) of Sergestes vigilax (Stimps.) H. J. H., in:
Mindeskrift for Steenstrup, 191 3) shovved that the petasma begins to be visible in the Masti-
go/>7<s-stage and has a gradual development; he gives six figures to illustrate the development
and makes some remarks on them, but he did not undertake a more close comparative invest-
igation. For the rest, already in 1896 I had pronounced (op. cit.) that "the petasma itself does
not become completely developed at once to its final shape". But when Stephensen writes :
"As may be seen the petasma varies very much with the age, and thus may not be used as
a specific character", this conclusion is extremely wrong. In the order Euphausiacea the copul-
atory organs, to which also the not very necessary name "petasma" could be applied, show a
gradual development, but while it in the adult specimens is of extreme importance for the
separation of species — and Zimmer, Tattersall and others have foliowed me as to this nearly
fundamental question — I have as a rule not taken into account the lobes and processes in
not full-grown males, and at least in its earlier stages the petasma is too little developed. And
the state of things is the same in Sergestes. But in order to obtain good and practical results
it is necessary to adopt an appropriate plan as to the petasma in adult specimens and to carry
through a nomenclature for its essential elements. According to my experience from the Euphau-
siacea, I think that the left organ ought as far as possible to be chosen; when the animal is
seen from below consequently the petasma on the side turning to the right. This organ is cut
off, laid on a glass-plate in glycerine diluted with water, cautiously spread as far as possible
by the aid of two minute knifes, then a small glass-cover is applied in such a way that the
organ is not much pressed, and the organ is then drawn, consequently from behind (from below).
Furthermore the distal portion of its median and most important, ramified part ought to be
drawn with a higher degree of enlargement both from behind and, after the organ has been
turned, from in front. When each petasma of several species has been drawn with its lobes
turning upwards on the paper in the way described, the organs are easily compared and the
differences affording specific characters catch the eye. The right organ is completely symmetrical
with the left, but the latter ought to be preferred. It may be added that when one has made
himself acquainted with the petasma in a few species or when he has a number of satisfactory
figures at hand, he may as a rule find it unnecessary to remove the petasma from any male in
order to use it for determination, as the examination with a good pocket-lens will be sufficiënt.
The petasma consists of three main-parts, viz. pars media (PI. I, fig-. ia, m., fig. 2a,m.,
fig. 6e, ;;/.), an inner plate, pars astringens (PI. I, a. in figs. ia, 2a, $è, ja; PI. II, a. in
fig. 2g), and an outer plate, pars externa (PI. I, fig. ia, e.). Pars astringens (a.) is always
a thin and generally rather large plate, which is fixed along the proximal portion of the inner
margin of pars media; the plate has generally a longitudinal folding, and its inner margin
which is long and straight, is equipped with a large number of extremely small hooks, by which
the plate of the left organ is coupled with the corresponding plate of the right one. Pars
externa (e.) projects from the proximal part of the outer margin of pars media ; it consists of
a rather large plate, lamina externa (PI. I, lam. in figs. ia, 2a, $6, 6e, ja, and PI. II,
lam. in fig. 2g) which anteriorly is produced into a generally long process, processus

u n c i f e r (pii. in the same figures), a name chosen for the reason that in most species (but
not in S. orientalis, PI. II. fig. 2g) it is deeply incised at the end on the inner side, so that
a strong hook is formed. Pars media {PI. I, fig. ia,m., fig. 2«, ?«., fig. 6e, m.) is the largest
and by far the most important portion of the petasma; it is connected with the peduncle of
the pleopod by a short piece projecting from the outer side near the base (see f. inst. PI. I,
fig. ja); at the origin of that piece is found a process, processus basalis (PI. I. pb. in
figs. ia, 2a, T,b, 6e, ja) directed (on the figure) backwards and inwards, and differing in shape
according to species. Inside that process is seen an incision, and inside this the inner proximal
portion of pars media, which has its proximal margin incurved and in the main transverse.
More or less beyond the middle pars media is-ramified, with a process and some branches or
lobes. I have attempted to find out the homologies of these ramifications in the different species
and have named them accordingly, because it is necessary to mention each process in the
description of the species. The first of these ramifications is named processus ventralis (pv.
in the figures), as it originates on the posterior or lower side of pars media; it differs exceedingly
in shape and affords excellent characters, as may be observed by a comparison of pv. in the
following figures on PI. I: figs. \b and \c, 2b and 2c, $c and $d, 4/ and q.g, jb and je,
and it has no hooks excepting in 5. Gardineri (figs. 2b and 2c), while in 5. seminudus (figs.
7 b and j c) it is armed with thick, short spines, and in 5". orientalis (PI. II, fig. 2/1, pv.) it is
quite small. The portion beyond the origin of processus ventralis is named capitulum, and
it has generally four lobes, in a few cases five or six. The most proximal lobe projects mainly
on the outer side and is named lobus armatus (PI. I, Ia. in figs. ib and ie, 2b and 2c,
2,b and 3 c, jb and je, and more anomalous in figs. \f and 4g, 6/ and 6g); it has always
a number of hooks ; the arrangement of these hooks and sometimes their size together with
shape and size of the lobe afford fine characters. The hooks on this lobe and on most or all
the other lobes show considerable differences in shape and extreme differences as to size, and
the membrane around them is generally invaginated, frequently to such a degree that the hook
is completely retracted. (In 1S82 S. J. Smith published a good description with figures of such
hooks in Scrgcstes robustus). The three other lobes are named respectively : lobus connec-
tens (Ie.) which projects mainly outwards and has a single hook or generally a number of
hooks ; lobus terminalis (//.) which varies as to hooks, and lobus inermis (li.) which
originates at the inner margin of the capitulum, possesses hooks in 5". Gardineri (figs. 2a and
2 b) but not in the other forms, and is wanting in S. Challengeri and S. fulgens (PI. I, figs. 4./
and 4g, figs. 6/ and 6g). But in the two last-named species we find on the anterior side of
the capitulum near the origin of processus ventralis two lobes, lobi accessorii (lac. on the
figures quoted) which have no equivalent in the other species, and both are armed with hooks.
In S. orientalis and S. Edwardsii a lobus accessorius is observed on the posterior side of the
capitulum towards its inner margin (PI. II, lac. in figs. 2/1, 2k and 3 a).

In 1896 I divided the species of Sergestes into two groups according to the length and
thickness of the third pair of maxillipeds as compared with third pair of legs, and the equip-
ment with bristles or spines on their distal joints. With a small amelioration in the wording of
the second of the two diagnoses this division is still very useful, and is reprinted later on,

The first of these groups was divided into two sub-groups according to the relative length of
the ciliated part of the outer margin of the exopod of the uropods, and this character is still
valid. Since 1896 some new species have been established; besides I have seen adult specimens
of a good number of species unknown to me twenty-two years ago, and my special study ot
the petasma shows that most species must be revised, as there exists some hitherto unrecog-
nized forms, and that many of the statements on distribution in the literature are not trust-
worthy. Though I have far from finished my intended investigations of the genus Sergestes
(and Petalidiuni) x) I think that a new tabular view of the species of the first group may be
useful. But before undertaking this attempt some remarks on the synonymy etc. ought to be
made. (On the forms of the second group nothing new can be communicated here, as the
ttSiboga" gathered only a single species).

Sergestes tenuiremis Kr. was established on a specimen in the Mastigopus-stage. In 1896
I stated that a specimen measuring 23 mm. had just acquired the black eyes, but I thought
that the adult was unknown. The study of partly new material from the Atlantic yielded the
result that 6". tenuiremis must be the Alastigopus of S. Króyeri Bate or more probably of
5". phorc2is Faxon, two species which are more closely allied than hitherto supposed. But as it
seems to be impossible to decide with absolute certainty whether the Kröyerian larva belongs
to S. p korens or to the other form I propose to drop the name tenuiremis, at most keeping
it as a designation for that elongated larval form.

Of S. bisulcatus Wood-Mason I have examined a co-type from the Indian Museum,
Calcutta, and three specimens described later on from the "Siboga". All specimens agree on
the whole well with Alcock's description. In 1893 Faxon established S. phorezes, but in 1895
he referred his specimens "with some doubt" to 5. bisulcatus Wood-Mason. Judging not only
from the shape of the rostrum as figured by Faxon, but especially from his figure of the
petasma his form cannot belong to Wood-Mason's species, and consequently the name S. phorcus
must be re-established. In his "South African Crustacea", Part III, 1905, Stebbing describes and
figures a form which agrees excellently with S. phorcus, but not with 5. bisulcatus, though he
follows Faxon in applying the latter name and cancelling 5. phorcus as a synonym. In the
material collected by the Prince of Monaco several adult specimens of S. phorcus are found.

S. prehensilis Bate is closely allied to S. bisulcatus Wood-Mas., but the eyes are larger
with shorter stalks, the antennular peduncles shorter as comparëd with the squama, and the
distal part of their first joint is broader. Besides the petasma of 5. prehensilis Bate differs very
considerably from that of S. bisulcatus \ Dr. W. T. Calman has kindly examined the petasma
in the holotype of 5. prehensilis Bate in the British Museum (Natural History) for me, and
according to his figures of the distal half of pars media the processus ventralis tapers from the
base to the obtuse end, lobus armatus is not half as long as in S. bisulcatus, with 3 hooks
on or near the end, lobus terminalis is thicker with about 7 hooks on the most distal part 01
its posterior side, lobus inermis is nearly twice as broad as long and with the end feebly

1) A paper on the Sergestida; gathered by the French expeditions "Travailleur" and "Talisman" in the Mediterranean and the
Atlantic is nearly ready for the press, and at present I work out the Sergestida: collected by the Prince of Monaco in the same seas.
Besides I hope later to study a fine material from the Pacific, etc.

produced 1). Sergentes prehensilis Nobili (1906) from lat. I4°57/N., long. 5i0io'E. cannot be
S. prehensilis Bate or S. bisulcatus Wood-Mason; whether is may be S. phorcus Faxon is
very uncertain.

Whether 5. viollis Smith from the North Atlantic is only a synonym to 5". japonicus
Bate cannot be settled with absolute certainty before the petasma of a male from the Japanese
seas has been studied; Bate's types in the British Museum are females. At present I am apt
to maintain my earlier opinion that 5. mol/is Smith is a synonym to 5". japonicus Bate.

5". rubro-guttatus Wood-Mason (1891) is probably impossible to determine with any
certainty from the description in the literature. An adult specimen received from the Museum
in Calcutta is an adult male of S. corniculum Kr.. But from the "Siboga" I have a number
of specimens of a closely allied form, S. seminudus n. sp., which can only be separated from
S. corniculum Kr. by the structure of the petasma. As I do not know whether 5. seminudus
is also to be found in the Bay of Bengal, the Andaman Sea or the Arabian Sea, it is impossible
to decide whether under the name 5. rubro-guttatus A. Alcock has only referred specimens
of 5. corniculum Kr. or besides some belonging to 5. seminudus n. sp.

Diagnoses of the two Group s.

Group I: Third maxillipeds at most but little longer, sometimes shorter
than third pair of legs; it first joint rarely, the second-fourth joints never
obviously incrassated in proportion to the joints in third legs, its two
distal joints with numerous bristles along both margins.

Group II: Third maxillipeds considerably or much longer than third pair
of legs, its four pjoximal joints considerably or (generally) very
much incrassated or partially almost inflated in proportion to the
joints in third legs, its two distal joints with a lesser number of bristles, most of
them or all small or minute, or totally naked along the one margin, the sixth joint
with a number of spines very different in length along the other margin, and a feebier
armature may also be found on the fifth joint.

Conspectus of the Species of Group I.

Only adult and subadult specimens are taken into consideration.
A. On the exopod of the uropods the ciliated part occupies considerably less than half of the
exterior margin.

a. The two distal joints of the antennular peduncles slender; third joint as long as or
longer than the inner margin of the second. Supra-ocular and hepatic spines well
developed.

1) 5. prehensilis Nakazawa and Terao (Zool. Mag. Vol. XXVII, n° 329) must be quite different from 5. prehensilis Bate, as
pars media of the petasma according to their figure (kindly copied for me by Dr. W. T. Calman) differs extremely from that in S. prehen-
silis Bate and every other species of the genus seen by me.

y.. Third joint of the antennular peduncles as long as or longer than first joint.

Species i — 2 : S. atlanticus M.-Edw. [S. Frisii Kr.), and
5". cornutus Kr.

(3. Third joint of the antennular peduncles very considerably shorter than first joint.

Spec. 3 — 4: S. arcticus Kr., and 5. affinis H. J. H.

b. The two distal joints of the antennular peduncles considerably or much thickened ;
third joint slightly or very considerably shorter than the inner margin of the second.
Supra-ocular spines always, hepatic spines most frequently wanting.

a. Eyes seen from above scarcely or at most a little broader than their stalks.
Third joint of the antennular peduncles slightly shorter than the inner margin of
second joint. Integument of the body soft and completely membranaceous.

Spec. 5 — 7: S. japonicus Bate [S. mollis Smith), S. inozes
Faxon, and S. profundus Bate.

r{j. Eyes seen from above considerably or much broader than their stalks. Third
joint of the antennular peduncles somewhat or considerably shorter than the inner
margin of second joint. Integument of the body moderately soft or somewhat
rigid, less membranaceous.

f. No luminous organs on the body or the appendages.

§. A process or protuberance on the inner side of the eye-stalks near
the eye. Spec. 8 — 9: S. Kröyeri Bate, and S. Gardineri Kemp.

§§. No distinct protuberance on the eye-stalks (in 5. phorcus a feeble
rudiment of a protuberance).

Spec. 10 — 13: 6\ phorcus Faxon, 5. bisulcatus Wood-
Mas., 5. prehensilis Bate, and 6". robushis Smith.

ff. Numerous luminous organs distributed on the body, especially on its lower
surface, and on most of the appendages.

Spec. 14 — 17: S. Challengeri H. J. H., 6". fulgcns n.sp.,
(S. splcndcns n. sp. in MS., Atlantic), and 5. glorio-
sus Stebb.

B. On the exopod of the uropods the ciliated part occupies somewhat more than half of the
exterior margin. (Slender forms with the antennular peduncles long).

Spec. 18 — 19 : 5". cornicuhim Kr., and S. seminudus n. sp.

It may be added that this conspectus is not only an analytical key aiding at the deter-
mination of specimens, but it gives besides a kind of classification, as the forms are collected
into small natural tribes. {Acheles arachnipodus Cocco (1832), which seems to be a species of
Sergestcs, is omitted, as it is probably impossible to recognize the form with complete certainty;
"Sergestes arachnipodus De Natale (ex Cocco)" as described and figured by Riggio (1905), must,
according to the equipment with spines of processus ventralis of the petasma, be S. arctictis Kr.).

The material collected by the "Siboga" comprises adult specimens of seven species.

8

A good part of the larvae can be determined, and among them are found specimens in the
Masiigopus-stages of .S. atlanticus M.-Edw., of which adult specimens were not taken, but as
these larvae can be determined with certainty, 5". atlanticus is dealt with below. — A single
specimen of a Mastigopus belongs to a hitherto unknown species of Group II, but it is omitted
as being somewhat mutilated and besides indeterminable.

1. Serges tes atlanticus M.-Edw.

1830. Ser gestes atlanticus H. Milne-Edwards, Ann. Sci. Natur. T. XIX, p. 346, PI. X.
1859. Ser gestes Frisii Kröyer, Kgl. Danske Vid. Selsk. Skrifter, 5. Raekke, Naturv.-math.

Afd. IV, 2, p. 235, Tab. I, Fig. \,a — v.
1888. Ser gestes atlanticus Bate, Challenger Rep. Vol. XXIV, p. 389, Pis. LXVIII & LXIX

(at least partially).
1896. Sergestes atlanticus H. J. Hansen, Proc. Zool. Soc. London for Dec. 1, 1896, p. 951.
1903. Sergestes atlanticus H. J. Hansen, Proc. Zool. Soc. London for 1903, p. 58.

The Mastigopus.

1859. Sergestes ancylops Kröyer, 1. c. p. 262, Tab. III, Fig. 8, a — e.
1888. Sergestes ancylops Bate, 1. c. p. 413, PI. LXXV, fig. 2.
1888. Sergestes ovatoculus Bate, 1. c. p. 408, PI. LXXIV, fig. 2.
1896. "-Sergestes ancylops" H. J. Hansen, 1. c. p. 952.

Stat. 203. Sept 19. Lat. 3°32'.5S., long. i24°is'.5E. Hensen vertical net, from 1500 m.

I Mastigopus.
Stat. 225. Nov. 8. 5700 m. N. 2790 E. from Southpoint of South-Lucipara-island. Horizontal

cylinder. 1 Mastigopus.
Stat. 276. Jan. 9. Lat. 6°47'.5 S., long. I28°40'.5 E. HENSEN vertical net, from a depth of

750 m. 1 Mastigopus.

The curious shape of the eyes, seen from above, renders the Mastigopus of S. atlan-
ticus easy to distinguish from all other forms hitherto known. In 1896 I pointed out that S.
ancylops Kr. and S. ovatoculus Bate are animals in Alastigopus-stages of 5. atlanticus, and in
1903 I gave a critical revision of the animals referred by Bate to S. atlanticus.

The Copenhagen Museum possesses an extremely large collection of adult and subadult
specimens of 5. atlanticus, all gathered near the surface or at most in some few fathoms below
it, and generally during the nights. S. atlauiic?ts belongs to the open ocean, and it is one of
the few species of Sergestes, which during all stages live near or not very far from the surface.

2. Sergestes inous Faxon. PI. I, figs. \a — \c.

1893. Sergestes inous Faxon, Buil. Mus. Comp. Zool. Vol. XXIV, p. 216.
1895. Sergestes inous Faxon, Memoirs Mus. Comp. Zool. Vol. XVIII, p. 208, PI. LI, figs. 2 — id.
1901. Sergestes sp. ? inous Alcock, Descr. Catal. Indian Deep-Sea Crust. Dec. Macrura and
Anomola, p. 50.

Stat. 35. March 28. Lat. 8°o'.3 S., long. u6°59'E. 1310 m. Deep sea trawl. 1 large male.
Stat. 175. August 30. Lat. 2°37'.7S., long. I30°33'.4E. 191401. Deep sea trawl. 1 immature

male.
Stat. 208. Sept. 22. Lat. 50 39' S., long. I22°I2'E. 1886 m. Deep sea trawl. 1 immature

specimen.

The large male measures 88 mm. from the tip of the rostrum to the apex of the
telson ; though very large, it is considerably smaller than Faxon's type, which was 1 1 3 mm.
long. This species is similar and very closely allied to 5. japonicus Bate (S. mollis S. I. Smith)
but it is very much larger, and differs, as already pointed out by Faxon and Alcock, sharply
by the posterior branchia of third pair of thoracic legs. The specimens from the "Siboga" have
the third maxillipeds mutilated, consequently I cannot fill up the gap in our knowledge.

The petasma (figs. \a — \c) which affords specific characters, has never been described.

Lamina externa {lam.) of pars externa (e.) is very long, a little longer than processus uncifer (pte.),

and its proximal half has its outer margin slightly convex. The processus ba'salis (pó.) is rather

slender, moderately short, with an acute angle on the otherwise moderately broad terminal part.

The middle portion of pars media (;«.) is rather slender. Processus ventralis (pv.) is long, nearly

straight, moderately slender, slightly broader beyond the middle than at the base, while its

distal fifth tapers to the subacute end. Lobus armatus (Ja.) is much curved, decreasing from

before the middle to the narrowly rounded end; somewhat less than its proximal half of the

inner side has a moderate number of invaginated hooks, and a somewhat shorter distal portion

of the anterior and the outer sides has several hooks, while the long middle portion

of the lobe is completely unarmed. Lobus connectens Je.) is long, protruding beyond

the other rami of pars media, thick at the base, subconical, with the end narrow but obtuse;

the outer surface of the lobe has a good number of hooks, the most proximal among them

quite small, and the terminal narrow part of the lobe has similar small hooks both on the

inner and the anterior surface. Lobus terminalis (//.) is very short and thick, with a moderate

number of small hooks at the end and along the distal part of the outer and the inner margin.

Lobus inermis Ji.) is only about one-third as long as lobus connectens, curved, very slender with

the end acute and without any hooks. Pars astringens (a.) does not exhibit any peculiarities.

The petasma described is allied to that of S. japonicus1), but differs in several features;
lobus inermis is more slender, curved and acute; lobus connectens has its proximal two-thirds
much thicker and besides a lower number of hooks, as the lobe in S. japonicus has numerous
hooks on the major part of its posterior surface and at the distal half of the inner margin .
lobus armatus is much thicker than in the other form and its long middle portion without
hooks, while in S. japonicus the lobe has numerous hooks distributed in its whole length both
on the posterior side and especially on its anterior side towards the inner margin. Among these
characters those found in the last-named lobe are probably the most valuable.

Distribution. — The type was secured in the tropical East Pacific at lat. 4°3'N.,
long. 8i°3i'W., 899 fathoms. The specimen described by Alcock has been taken in the
Arabian Sea, 1091 fathoms.

3. Ser gestes Gardineri Kemp. PI. I, figs. 2a — ie.

1913. Sergestes gardineri Stanley Kemp, Trans. Linn. Soc. Lond. 2. ser., Zool. Vol. XVI,
pt 1, p. 55, PI. 7, figs. 2—5.

1) Figured in my forthcoming report on the Sergestida: from the "Travailleur" and the "Talisman".
SIBOGA-EXPEDITIE XXXVIII.

IO

Stat. 141. August 5. Lat. i°o'.4S., long. I27°25'.3E. 1950 m. HENSEN vertical net, from
1 500 m. depth to surface. 1 adult male.

Stat. 230. Nov. 14. Lat. 3°58'S., long. i28°2o'E. HENSEN vertical net, from a depth of
2000 m. to surface. 1 adult female.

This species is somewhat small; the largest "Siboga" specimen, the female, is 26 mm.
lono-, and the adult male a little smaller. The body is somewhat thick, the legs moderately
short and a little robust. It has on the whole been well described by Kemp, but the eyes and
their stalks do not agree fully with his figures, and besides some particulars and especially a
representation of the petasma must be added.

The carapace and its rostrum has been fully described by Kemp ; it may be noted, that
the distal part of the rostrum, beyond the dorsal tooth, is more straight in my animals than
figured by him. His description and figures of the eyes disagree somewhat with my specimens-,
the eyes are in both sexes conspicuously larger than figured by Kemp and considerably broader
than their stalks, somewhat broader than deep; besides the cornea is as long as the outer
margin of the distal joint of the stalk; the protuberance at the inner margin of the stalk near
the cornea is a little conical, quite low, and broadly obtuse. — Kemp's statement that in the
antennulae the third joint of the peduncle is slightly longer than the second does not agree
with his fig. 3, as the inner proximal part of 'second joint must be counted; in reality second
joint is in the female a little longer than the third, and in the male the difference in length
is still more conspicuous ; besides the second joint is somewhat thicker in the male than in the
female, while there is considerable difference in the third joint between the sexes, as in the
female it is about as broad as deep, while in the male it is a little obliquely compressed, seen
from above as broad as in the female, but much deeper than broad. The two proximal joints,
and especially the first joint, of the clasping organ in the male are short and somewhat thick,
but the organ is unfortunately rather mutilated. The antennal squama has its rather narrow
end more transversé and the outer terminal tooth longer than in Kemp's fig. 3 ; the squama
has numerous small darker dots arranged in its whole length in a straight line a little nearer
to the inner than to the outer margin.

To Kemp's description of the appendages may be added that third pair of maxillipeds
is a little shorter and more slender than third pair of legs ; in the only maxilliped not mutilated
I was unable to detect any subdivisions of the terminal joint. Fourth pair of legs, when directed
forwards, reaches slightly beyond the end of the rostrum ; their two distal joints are somewhat
broad, the terminal one being scarcely five times as long as broad; fifth pair of legs about
half as long as the fourth. As to the branchise and the uropods is referred to Kemp.

The petasma (figs. 2a — 2 c) is very characteristic. Lamina externa {lam.) of pars externa
is short, much shorter than processus uncifer {pit.) and has its outer margin concave at the
middle ; the process named differs from that in other forms by the shape of the subterminal
incision, which in 5\ Gardineri is longer than deep, while in other species it is narrow, deeper
than long. Processus basalis {pè.) is very broad, moderately long, distally very broadly rounded.
Pars media is moderately robust at the middle. Processus ventralis {pv.) is long, curved, scarcely
tapering from somewhat from the base to the end, which is cut off obliquely and equipped

1 1

with about six hooks of middle size. Lobus armatus {la.) is of moderate size, thick at the base
and tapers to the end; it has a good number of hooks along the inner side from rather near
the base to the end, and a few hooks on the front side near the end. Lobus connectens (/e.)
is not half as long as lobus armatus and as thick as processus ventralis at the middle ; it has
a good number of hooks on most of its anterior side and a few on the posterior side. Lobus
terminalis (//.) is long, straight, a little tapering, with about four hooks spread along the outer
margin and three hooks at the most distal part of the inner margin. Lobus inermis (//.) is
long, thicker than the other lobes, somewhat curved, distally tapering to the obtuse end, with
about four hooks at the distal part of the outer margin and three large hooks at the distal
part and the end of the inner margin.

Remarks. — ■ In possessing a very distinct protuberance on the eye-stalks near the
cornea S. Gardineri agrees with 6". Kröyeri Bate, but differs from all other species of this
sub-group (in the other sub-group, comprising S. cornimlum Kr. and S. semimidus n. sp., a
distinct protuberance is less or more developed). 5. Gardineri differs from 5. Kröyeri in being
much smaller, in having the protuberance mentioned much lower and of another shape, in a
totally differently formed rostrum, and other particulars. The petasma in 5. Kröyeri has never
been described; that in S. Gardineri differs from those hitherto known of the species in group I
in three features, viz. the shape of the subterminal incision in processus uncifer, the occurrence
of hooks on the end of processus ventralis, and the existence of hooks on lobus inermis.

Distribution. — Kemp recorded several specimens from three localities in the western
part of the Indian Ocean somewhat south of the line, two among them in depths between
750 and 500 fathoms.

4. Ser gestes bisulcatns Wood-Mason. PI. I, figs. $a — T,d.

1891. Sergestes bisulcatus Wood-Mason, Ann. Mag. Nat. Hist. 6 ser. Vol. VII, p. 190.

1901. Sergestes bisulcatus Alcock, Illustr. Zool. Investigator, PI. L, figs. 1, la, ïb.

1901. Sergestes bisulcatus Alcock, Descr. Cat. Indian Deep-Sea Crust. Dec. Macrura and
Anomala, p. 49.

Stat. 46a. April 7. Lat. 8° o'. 5 S., long. u8°34'.7E. 1600 m. Deep sea trawl. 1 adult female.
Stat. 185. Sept. 12. Lat. 3° 20' S., long. i27°22'.9E. Manipa Strait. Hensen vertical net,

from 1536 m. to surface. 1 adult male.
Stat. 217. Oct. 31. Lat. 6°4o'.6S., long. 123° I4'.7 E. 2477 m. Deep sea trawl. 1 immature

specimen.

In general aspect somewhat similar to S. robustus S. I. Smith. Alcock has published
a description which on the whole agrees well with the "Siboga" specimens and with a co-type
received by the Copenhagen Museum many years ago from the Museum in Calcutta. Here it
may be sufficiënt to mention some particulars and describe the petasma.

The rostrum is somewhat ascendant (fig. 3), moderately long, acute; the lower margin
has its distal third or nearly more than its distal half feebly or somewhat concave, while the
upper margin is a little or slightly convex or feebly angular beyond the middle. The eyes are
large, nearly as long as broad, distinctly depressed, much broader than the stalk and slightly

12

lono-er than the outer margin of its distal joint; the stalk is manifestly longer than in S. robustus.
The antennulse in the main as in 5". robustus, but second and third joints of the peduncle are
distinctly less thick, especially third joint is longer in proportion to its depth than in S. robustus,
and there is much less difference between the thickness of its proximal part and near its end
than in the species named; furthermore third joint is similar in both sexes, somewhat compressed,
and conspicuously shorter than second joint. The antennal squama is rather far from reaching
the middle of the third peduncular joint of the antennulae; it has the terminal margin of
moderate length, a little convex and nearly transverse, and the marginal spine is well developed.
The terminal joint of third maxillipeds is divided into four joints subequal in length, but each
of the two distal subjoints is again divided into two joints; the result is thus six subjoints in
all. Fourth pair of legs, when stretched forwards, reach a little beyond the apex of the rostrum ;
the two distal joints are proportionately narrower than in 5. Gardineri. The posterior branchia
above third pair of legs is a little more than two-thirds as long as the anterior, and about as
long as the second branchia above fourth legs, while this last-named branchia is scarcely three-
fourths as long as the anterior branchia above the same legs. All these four branchiae are long
and closely set, rather similar to those in 5. robustus, from which they differ in the feature,
that the posterior branchia of each of the two sets is shorter in comparison with the anterior
branchia of the same segment than in 5. robustus.

Alcock's description of the petasma is completely insufficiënt. — Lamina externa {lam.)
of pars externa is short, much shorter than processus uncifer (pu.), with the outer margin feebly
ano-ular a little beyond the middle, and its proximal part nearly straight; processus uncifer is
uncommonly slender, with the subterminal incision normal, somewhat deep. Processus basalis {pb.)
is nearly straight, rather slender, moderately short, slightly broader beyond the middle than at
the base, with the distal fourth rapidly tapering to the acute end. Processus ventralis (pv.) is
rather long, moderately strong, a little curved, tapering a little from the base to the middle,
while the distal half widens gradually a little again and then tapers to the acute end. Lobus
armatus (la.) is long, reaching beyond the processus ventralis; it is somewhat curved, thick at
the base and then tapering considerably ; the distal half is moderately slender, keeping at least
the same thickness to the oblong and tapering terminal part; the obtuse end has a very large
hook; on the inner side a large hook is found considerably beyond the middle and a smaller
hook near the middle, while the proximal half of the inner margin has about seven small hooks,
some of them even shaped as acute, somewhat curved papilla;. Lobus connectens (Ie.) is, seen
from behind (fig. 3^), nearly totally overlapped by the lobus terminalis; it is moderately short,
thick (fig. 30Q, tapering to the truncate end which has a couple of hooks, while some minute
hooks are found on the distal part of the inner margin. Lobus terminalis (It.) is rather long,
curved, its basal third very thick, as it is expanded on the outer side, and the outer margin
of this part has about seven small hooks; the distal two-thirds taper to the truncate end which
has a very large hook. Lobus inermis (li.) is somewhat shorter than lobus connectens but reaches
to its end; it is moderately stout at the base but tapers rapidly, so that its distal third is very
slender; it has no hooks.

Length cannot be stated with accuracy, as the adult specimens are much curved. The

13

female is not far from being 62 mm. long, thus about as large as the largest specimen measured
by Alcock; the male is not inconsiderably shorter than the female.

Remarks. — S. bisulcatus is allied to the common North-Atlantic form S. robustus
Smith, but differs in having the cervical furrow very pronounced on the dorsal surface of the
carapace, another shape of the rostrum, proximal half of third joint of the antennulêe less thick,
and in some other particulars; the petasma is very different from that in S. roóustus. As pointed
out above, S. bisulcatus Faxon (= S. bisulcatus Stebbing) is another species, which must keep
its older name S. phorcus Faxon.

Distribution. — According to Alcock this species is common in the Bay of Bengal,
the Arabian Sea, and the Andaman Sea; the depths recorded are from 145 to 902 fathoms.

5. Sergestcs Challengeri H. J. H. PI. I, figs. \a — <\k.

1903. Sergestes Challengeri H. J. Hansen, Proc. Zool. Soc. London for 1903, vol. I, p. 61,

PI. XII, figs. 2a — 211.
191 3. Sergestes challengeri Stanley Kemp, Trans. Linn. Soc. London, Zool. 2. ser., Vol. XVI,

pt I, p. 54, PI. 7, fig. 1.

Stat. 46a. April 7. Lat. 8° o'. 5 S., long. 11834'./ E. 1600 m. Deep sea tjawl. 1 adult female.
Stat. 89. June 21. Pulu Kaniungan ketjil. 11 m. Shore exploration. 1 immature male.
Stat. 141. Aug. 5. Lat. i°o'.4S., long. i27°25'.3E. 1950 m. Hensen vertical net, from 1500 m.

depth to surface. 2 females.
Stat. 143. Aug. 7. Lat. i°4'.5 S., long. 127° 52'.6 E. 1454 m. Hensen vertical net, from 1000 m.

depth to surface. 2 young specimens.
Stat. 148. Aug. 10. Lat. O0 if.6 S., long. 1290 14.5 E. 1855 m. HENSEN vertical net, from

IOOO m. depth to surface. 1 adult male, 2 immature specimens, and 1 Mastigopus.
Stat. 185. Sept. 12. Lat. 3°2o'S., long. i27°22'.9E. Hensen vertical net, from 1536 m. to

surface. 5 adult males, 4 females, 2 immature specimens.
Stat. 243. Dec. 2. Lat. 4°30.2S., long. i29°25'E. Hensen vertical net, from 1000 m. to

surface. 2 young specimens.

a. Adult Specimens. — This species was established on a single mutilated specimen.
A large number of luminous organs were pointed out, and no other species with such organs
was known. In 1905 Stebbing described an allied species, 5". gloriosus, from off South Africa,
but in this form the luminous organs are still considerably more numerous than in S. Challengeri,
and the animal is much larger. In the manuscript to the paper on the Sergestidae from the
"Travailleur" and "Talisman" I have described a third species secured by the last-named
expedition in the tropical Atlantic; this species, which I name S. splendens n. sp., is as large
as S. gloriosus, viz. about 50 mm. in length, but it differs from S. gloriosus and agrees nearly
with 5". Challengeri as to the number of luminous organs. Finally, the "Siboga" has captured
many specimens of a fourth species, to be described later on, S. fulgens n. sp. ; it is about as
large as S. gloriosus and S. splendens, while the largest specimen of S. Challengeri hitherto
seen is only 35 mm. long, and most of its specimens are less than 30 mm. These four luminous
species are very closely allied, in reality very similar in most features; S. gloriosus must be the
most easy to determine as it has a much higher number of luminous organs on the antennal
squama, the sides of the carapace etc. than found in the three other species.

In 191 3 Stanley Kemp published, based on about 4 specimens, a supplement to my
description of the mutilated specimen of S. Cliallengcri. He was able to describe and figure
the eyes, and it may be added that they are somewhat large, seen from above (fig\ 4Ó) about
as long as the inner margin of the distal joint of the stalk and very considerably broader than
the distal part of this joint. His specimens differed somewhat from the 'Challenger' type in the
shape and direction of the rostrum, but I have found some variation in this process, and add
a drawing (fig. 4a) showing its most common shape in the adults. His remarks on two joints
in the second pair of maxillipeds is correct. Finally he investigated the number and position
of the photophores ; he found the 1 1 7 organs enumerated by me, and it must be added that
he pointed out that the organs on the side of the carapace turn invvards, and according to my
observation there are generally 4, sometimes 5 organs in the line on each side of the carapace.
Furthermore he found 18 organs on appendages — eye-stalks and the two posterior pairs of
thoracic legs — missing in my type, finally in all 4 organs on the three posterior abdominal
segments and not observed — probably overlooked — by me. I may here correct a statement
in my paper as to the organs on first pair of thoracic legs; each leg has, as stated, 3 organs,
but one is placed proximally on the third joint, the two others near each end of fourth joint.
As three pairs of appendages have never been examined, it may be added here that third
pair of maxillipeds have 4 organs, each placed distally on second to fifth joints; each leg of
second and third thoracic pair has 3 organs, viz. 2 on the lower side of third joint, respectively
near the base and at the distal end, and a single organ distally on fourth joint. These three
pairs of appendages have consequently together 20 organs, which added to the number of
organs already known give the result that 159 organs, or, when the sides of the carapace have
in all 9 or 10 organs, 160 or 161 organs are found in this species. — It may otherwise be
sufficiënt to refer the zoologist to my earlier description and drawings of S. Cliallengcri as to
all external features excepting the third maxillipeds and differences between the two sexes,
which are entirely unknown.

Third maxillipeds are not inconsiderably shorter than third pair of legs ; the terminal
joint is divided into four sub-joints, the first considerably shorter than the second which is
somewhat shorter than the third and a little shorter than the fourth.

The antennulae show strong sexual difference. Third peduncular joint in the female is
robust and distinctly deeper than broad; seen from the side and slightly from below (fig. 4^)
its distal third has the margins nearly parallel, and this part is a little less deep than the
proximal half. In the male the third joint is scarcely as long as in the female of the same size
but much deeper, and its distal third is below produced into a large triangular part (fig. 4c),
the distal lower corner of which is a triangular, acute process directed downwards and much
forwards-, in one specimen the front margin of the produced or expanded part has a smaller
triangular tooth above the process mentioned (fig. \d), while in other specimens this tooth is
rudimentary or wanting (fig. 4c). — The lower antennular flagellum is in the female simple as
usual, in the male (fig. 4c) its clasping organ is strongly built and characteristic. The upper
process from its first joint is seemingly nearly divided into two portions, the proximal one being
moderately thick and a little curved with the convex margin upwards, while the distal portion,

15

which is somewhat shorter and more slender than the proximal, is strongly curved with the
convexity downwards and the end acute. Second joint is thick at the base and tapers to the
end ; its upper margin has about twelve thick setae, the few proximal of them moderately short,
while the othecs are quite short and towards the end extremely short, more similar to teeth
than to setae; third joint is moderately thick, expanded upwards from base to end; the other
joints are slender.

The petasma is very different from those in the preceding species, but so similar to that
in the following form, S. fulgens, that the outline of the organ in the last-named species (fig. 6 e)
is deemed sufficiënt for conveying a general idea, while the distal half of pars media in 5.
Challengeri is shown from behind (fig. 4/) and from in front (fig. 4^). Lamina externa {la. in
fig. 6e) is considerably shorter than processus uncifer (/«.), with the outer margin angular
beyond the middle, its proximal part concave and the distal part a little convex; processus
uncifer is somewhat slender, with its most distal part a little or not widened on the inner side
(fig. 4/j). Processus basalis is somewhat slender, a little curved, distally subacuminate and acute.
Pars media is somewhat robust. Processus ventralis {pv. in figs. \f— \g) is of middle length,
moderately thick at the base, from which it tapers nearly gradually to the acute end, and its
distal part is curved much outwards. Lobus armatus {la.) is long and thick; it has an extremely
large hook on the inner side somewhat from the end, which is cut off and has a large hook,
while about nine hooks, the six distal moderately large, the others small, are seen as a ven-
oblong group on the posterior side near the outer margin. Lobus connectens (/ir.) is scarcely
half as long as lobus armatus, very thick and besides much expanded towards the end, which
has a long terminal margin rather deeply excavated somewhat nearer its inner than its outer
end, so that the most distal part of the lobe is divided into two short and thick secondary
lobes, the outer considerably thicker than the inner; the distal margin of the inner secondary
lobe has three large hooks, the distal and outer margin of the outer lobe has about seven
smaller hooks, and besides the entire lobe has on the front side (fig. \g) a median longitudinal
row of hooks and about three hooks towards the outer margin somewhat before the end. Lobus
terminalis (//.), which is almost as long as lobus armatus, is very peculiar and without hooks ;
its proximal part is directed essentially inwards, and then it suddenly is bent, directed forwards
and distally curved outwards ; its distal end is in the specimen figured deeply concave with each
lateral corner produced into a triangular, acute process, but this end varies much individually,
as sometimes only one produced and acute lateral angle is found, sometimes the end is feebly
emarginate and generally it is rounded (as in 5. fulgens, fig. 6 f). Where the subproximal bend
is found on the lobe, the angle protrudes less or more, and from comparison with the organ
in S. splendens n. sp. (Atlantic) I am induced to think that this protruding part is a quite
rudimentary lobus inermis. Finally we find on the front side of pars media (fig. \g) near the
origin of processus ventralis two lobi accessorii {lac), the outer slender and rather long with
a large hook on the end, the inner lobe scarcely half as long but much thicker than the other,
with about six hooks on its anterior side.

Length of a large adult male 31.5 mm., of a large female 35 mm.

6. Younger Stages. — One of the smallest specimens with black eyes is scarcely

ió

1 7 mm. long. The eyes are distinctly smaller with their stalks proportionately longer, and the
rostrum is less produced than in the adults, but the most interesting difference is that fewer
photophores are found. These organs are well developed on the lower side of the thorax, but
on each side of the carapace only one organ exists, while the antennal squama, which is easily
examined, has only two organs ; the more special, very difficult search for photophores has not
been undertaken. — One of the largest specimens with the thick outer layer of the eyes
yellowish, is 13 mm. long; it is a transition-stage between the real Mastigopus and the young
specimen with black eyes just mentioned. It differs in having the antennular peduncles (fig. 42)
conspicuously less robust and the eyes considerably smaller with their stalks longer-, the rostrum
has a small, acute angle above, while its distal part is slender, acute-, the two posterior pairs
of thoracic legs are less developed, and sixth abdominal segment has its posterior upper angle
produced into a very small spine. Several well developed photophores are found on the lower
side of the thorax; second maxilliped has at least four organs, and an organ is found on the
lower side of the eye-stalks near the eye, but no organ could be discovered on third maxil-
lipeds, on the thoracic legs, the sides of the carapace and above all on the lower side of the
antennal squamse. — Figs. \l and 4^' represent respectively the anterior part of the body and
the exopod of left uropod of a real Mastigopus measuring 12.3 mm. in length. It is seen that
the rostrum (<?.) is small with a small upper tooth, while the eye-stalks are long, so that the
eyes, which are considerably larger than in the stage just mentioned, are situated above the
articulation between first and second joint of the antennular peduncle; this peduncle is as usual
in Mastigoptis-ioxm?, rather slender; fifth and sixth abdominal segments each with a small spine
on the upper posterior angle ; the ciliated part of the outer margin of the exopod of the uropod
(as usual in this sub-group of Sergestes) distinctly longer in proportion to the naked part than
in the adult ; finally it was impossible to find any photophores on the ventral side of the thorax
or on second maxilliped, and they are probably entirely wanting.

Remarks. The differences between S. Ckalletigeri, S. splendens n. sp. (from the Atlantic)
and 5. ftilgens are mentioned in the description, with remarks, of the last-named form.

Distribution. — The 'Challenger' specimen was taken at "Lat. i90a/.35S., long.
i79°4i'.50 E.; off Matuku, Fiji Islands; depth 315 fathoms". Kemp's specimens were gathered
in the western part of the Indian Ocean, viz. at lat. io°27'S., long. 5i°i7'E., 800 — o and
1000 — o fathoms, and "6 miles N. N.W. of Desroches Atoll", 200 to o fathoms.

Sergestes sp. PI. I, fig. 5 a.

Stat. 100. June 29. Lat. 6°n'N., long. 1200 37'. $ E. 450 m. Dredge. 1 adult male.

The single male, which measures 32.5 mm. in length, cannot belong to 6". Challengeri\
it is very closely allied to this species, agreeing with it in the petasma and every other
particular, but the third joint of the antennular peduncle and the lower flagellum are very
different. The distal part of that third joint (fig. 5a) is slightly expanded downwards, but its
lower part is produced considerably forwards, with its terminal inferior corner cut off obliquely
and bearing a long and extremely thick, acute seta or spine. The lower flagellum differs

17

extremely from the clasping organ in the male 5. Challengeri or 5. fulgens, as it is more
similar to the flao-ellum in a female, from which it differs only in having the second joint
(fier. ca) lono-er and above at the end produced into a small, obtuse process. Third joint of the
peduncle and the proximal joint of the lower flagellum are rather similar to the same parts in
the Atlantic form S. splendens, through showing differences in two or three small particulars;
the petasma agrees with that in S. Challengeri, and differs from 5. splendens in a few small
features. The specimen is mentioned here, as future investigators with a richer material of these
luminous forms of Sergestes ought to keep outlook in order to solve the difficulties.

6. Sergestes fulgens n. sp. PI. I, figs. 6 a — 6g.

Stat. 312. Febr. 14. Lat. 8° 19' S., long. ii7°4i'E. Saleh-bay, North coast of Sumbawa. 274 m.
Trawl. 22 specimens, 16 of which are adult males.

This species is so closely allied to 5. Challengeri that a half-grown female can scarcely
with absolute certainty be distinguished from an adult female of the last-named species excepting
by the fact, that in the latter the antepenultimate thoracic segment has its lower surface between
the coxae adorned with keels and protuberances, which are not found in the immature S. fulgens.

S. fulgens is much larger and looks proportionately more robust than -5. Challengeri.
The rostrum (fig. 6a) is distinctly longer than deep, thus somewhat more produced than in
S. Challengeri. The eyes are seemingly a little larger in proportion to first joint of the anten-
nular peduncles, and a little longer in proportion to their stalks than in 5. Challengeri. The
terminal joint of third maxillipeds (fig. 6d) is as in the last-named species divided into four
sub-joints, each of the two distal conspicuously longer than the second and especially than the
first, but third sub-joint is sometimes, but scarcely always, more or less distinctly subdivided
into two joints, as shown in the figure. By far the best character between S. fulgens and the
other luminous forms is the shape of third joint in the antennular peduncle in the male. This
joint (fig. 6b) is extremely characteristic and shows no variation worth mentioning in the numerous
adult males examined. The distal third of the joint is on the lower side produced strongly
downwards, somewhat forwards and a little inwards as a plate which has a very deep and
rounded terminal incision so that both the lower anterior and the posterior corner of the plate
have each a long process ; the anterior process is straight and considerably longer than the
posterior, a little curved process, and both processes have the end obtuse. The clasping organ
of the lower flagellum (fig. 6e) is shaped nearly as in vS. Challengeri, but the curious setse along
the upper margin of second joint are about sixteen, and the most proximal setae are longer,
the most distal ones thicker than in S. Challengeri. — The carapace has on each side either
6 or 5 photophores in a row.

The petasma (figs. 6 e — 6g) is so similar to that in S. Challengeri described above that
some remarks may be sufficiënt. The distal part of processus uncifer (fu.) is conspicuously
expanded inwards. The hooks on the posterior side of lobus armatus (la.) near its outer margin
are smaller and somewhat more numerous than in 5. Challengeri. Lobus connectens (Ie.) has
the distal margin less deeply curved, the outer lobe more narrow, the inner broader than in

SIBOGA-EXPEDITIE XXXVIII. 3

i8

the preceding species, besides the hooks along the outer and the distal margins are a little
smaller and a little more numerous, and the hooks in the longitudinal row on the anterior side
(fig. 6g) are considerably smaller. The inner proximal bend on lobus terminalis [It.) is more
produced almost as a low and broad protuberance. The inner one of the accessory lobes
(fig. 6g, lac.) is short and thick.

Rem ark s. — It may be seen that the two really valuable specific differences between
S. fulgens and S. Challengeri are the size of the adults and the shape of third joint in the
male antennular peduncles. But this joint differs strongly in the two forms, and as no inter-
mediate form has been observed the character must be of specific value. In my description of
S. splendens (manuscript on the 'Talisman' Sergestidae) I have pointed out that the same third
joint in this species differs rather little from that in the female, as it has no process directed
downwards, furthermore that the lower antennular flagellum in the male has its proximal part
somewhat feebly thickened with a rather small and distally rounded protuberance on second
joint, thus the whole structure differing widely from what is found in S. Challengeri and S.
fulgens, but somewhat similar to the above-mentioned indeterminable male from "Siboga"
Stat. ioo. In the French paper I have also described and figured the ventral side of the four
posterior thoracic segments of the female, showing the adornment of the antepenultimate seg-
ment between the coxa^, and pointing out that a similar structure is found in S. Challengeri
and S. fulgens, but that in these the keels, and especially the two posterior protuberances, are
less developed than in S. splendens, differences not easy to use as characters and scarcely
possible to figure accurately. Finally the petasma of S. f eigens differs from that in S. splendens
in some minor particulars, among which those found in the shape of lobus terminalis are
perhaps the most important.

7. Serges/es seminudus n. sp. PI. I, figs. ja — "je-, PI. II, figs. ia — \f.

Stat. 66. May 7 — 8. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer.

8 — 10 m. Plankton. 6 Mastigopus.
Stat. 144. August 7—9. Anchorage north of Salomakiëe-(Damar-)island. 45 m. Plankton.

6 Mastigopus.
Stat. 148. Aug. 10. Lat. o°i7'.6S., long. 1290 14'. 5 E. Hensen vertical net, from 1000 m.

depth to surface. 4 specimens (1 is an adult male).
Stat. 157. Aug. 15 — 16. Lat. o°32'.9S., long. I30°I4'.6E. 45 m. Plankton. 1 Mastigopus.
Stat. 168. Aug. 22 — 23. Anchorage North of Sabuda-island. 6^ m. Surface. 1 Mastigopus.
Stat. 177a. Sept. 1. Lat. 2°3o'S., long. I29°28'E. Townet. 1 Mastigopus, 3 Acantliosoma.
Stat. 185. Sept. 12. Lat. 3°2o'S., long. i27°22'-9E. Manipa-strait. Hensen vertical net, from

1536 m. to surface. 3 males, 1 large female.
Stat. 189a. Sept. 12. Lat. 2°22'S., long. I26°46'E. Townet. 1 Mastigopus.
Stat. 194-197. Sept. 15. Lat. i° 55'-i°45'.3 S., long. 126°39'-I27°8'.3 E. Plankton. 1 Mastigopus.
Stat. 203. Sept. 19. Lat. 3°32'.5S., long. I24°I5'.5 E. Vertical net from 1500 m. depth to

surface. 1 young specimen, 1 Mastigopus.
Stat. 223. Nov. 6. Lat. 5°44'.7S., long. i26°27'.3E. Surface. 1 Mastigopus.
Stat. 230. Nov. 14. Lat. 3°58'S., long. i28°2o'E. Hensen vertical net, from a depth of

2000 m. to surface. 1 adult male.
Stat. 276. Jan. 9. Lat. 6° 47'. 5 S., long. i28°4o'.5 E. Hensen vertical net, from 750 m. to

surface. 1 Mastigopus.

19

a. Ad uit Specimens (PI. I, figs. 7 a — 7 c ; PI. II, figs. ia — 16). — Very similar to
S. comiculum Kr. Both species together constitute a sharply defined tribe of group I of Sergestes.
Here may be given a somewhat detailed description of S. seminudus, but as it is so similar to
* 5. comiculum that it will be difficult to point out any valid specific difference between them
excepting in the male petasma, it may be sufficiënt to refer to my figures of various parts of
S. comiculum to be found in the future paper on the Sergestidse from the French expeditions.

The animal is slender, with a considerable distance between the mouth and the insertion
of the eye-stalks. The carapace is considerably compressed ; its rostrum is small or even very
small, somewhat or only a little produced forwards, with the distal parts of the upper and the
lower margin strongly converging and the end acute or produced into a minute, acute tooth.
A supra-ocular spine is wanting, but its crest is very conspicuous; the hepatic spine is small
but very distinct. The gastro-hepatic groove is deep, and from its postero-lateral angle a very
conspicuous keel runs forward to the antenna. The upper and the anterior margin of the
branchial area is limited by a deep groove, and along the upper margin runs a strong keel,
while the cervical groove above the front part of the branchial area is nearly or quite indistinct.
The abdomen scarcely affords any valuable character; its sixth segment is a little less than
twice as long as deep.

The eyes are somewhat small, conspicuously shorter but much broader than the slender
and a little elongate distal joint of their stalks; on the inner margin of the stalk a little behind
the cornea is seen a rounded protuberance which sometimes is about as high as broad, most
frequently lower than broad. The antennular peduncles are long, about two-thirds as long as
the dorsal line of the carapace; first joint has its distal half narrower than in the preceding
species; second and especially third joint is slender; third joint is considerably shorter than the
first, somewhat longer than the second, and slightly thicker in the male than in the female.
The clasping organ on lower male fiagellum is slender and shaped as in S. comiculum. The
antennal squama tapers considerably towards the rather narrow, rounded end, and the tooth
on the outer angle is very small ; squama reaches the middle of third antennular joint. Third
pair of maxillipeds are a little shorter than third pair of legs, but the three proximal joints
are broader than in these legs; the terminal joint (fig. \a) is divided into 8 or 7 subjoints
(I have found both numbers in specimens from the same locality), but the interpretation is that
the joint is divided into 4 subjoints gradually distinctly shorter from the first to the fourth, and
that each of the three distal subjoints and sometimes besides the first subjoint is again sub-
divided into two joints. Fig. 1 b exhibits the long and thin terminal joint of first pair of legs.
The exopod of the uropods is about five times as long as broad and tapers from a little from
the base to the narrow end; scarcely two-thirds of its outer margin is ciliated, and there is no
marginal tooth.

The branchiae are somewhat similar to those in S. arcticus\ first branchia above third
pair of legs is conspicuously more than twice as long as the second, which is about as long
as the second branchia above fourth legs, while the first branchia above fourth legs is some-
what or considerably longer, and more than half as long as first branchia above third legs.

The petasma (figs. "ja — je) shows interesting features. Lamina externa {lam.) is distinctly

20

shorter than processus uncifer {f>u.); the proximal part of its outer margin is a little concave
and considerably longer than the distal part ; processus uncifer is somewhat slender. Processus
basalis (pb.) is of moderate length, conical, acute. Pars media is moderately slender. Processus
ventralis (pv.) is rather long, at the base extremely broad and tapers rapidly so that it in
more of half of the length is of moderate thickness; at the end it is expanded and cut off
vvith the terminal margin obliquely concave and the distal interior corner produced as a triangular,
acute process; in front along the terminal margin is found 8 triangular teeth. Lobus armatus
(/#.)- projects beyond the processus ventralis ; it is somewhat thick at the base, decreases towards
the obtuse end and is straight or only a little curved; its whole inner margin has a
row with about 13 hooks, the small terminal one included. Lobus connectens (Ie.) is
somewhat small, oblong triangular, directed outwards with about 8 hooks on the distal half of
its anterior side. Lobus terminalis {It.) is moderately short, not decreasing in breadth to the
obliquely rounded end and curved outwards-, its terminal part has a good number of hooks
especially on the margin and the front side. Lobus inermis (li.) is considerably longer than
lobus terminalis, directed forwards and somewhat inwards, tapers from rather near the base to
the narrow subacute end, and it has no hooks. — - (The thelycum differs much from that in
S. fulgens or S. Challengeri, but having only a single full-grown female it was found very
difhcult to draw a good figure, and without a figure a description of the protuberances and
impressions has scarcely any value).

Length of the adult female 46 mm., of a large male 37 mm.

b. MastigopusS t a g e s. — These larvse are scarcely discernible from those of S. corni-
culum Kr., which has been established on such larvae measuring according to Kröyer scarcely
13 mm. Kröyer and Bate published descriptions and figures of such forms. In 1896 I described
a young stage measuring 6.4 mm. in length; in 1903 I pointed out that 5. longirostris Bate
is a very young Mastigopus of the same species. The A/astigopus-stages of 5. comiculum and
and S. seminudus are distinguished from those of all other species of Group I by the exopod
of the uropods, as the ciliated part of the outer margin occupies from a little more than half
to about three-fifths of its length ; in the youngest specimens the end of the naked portion has
a well developed spine, and this spine is gradually reduced in size according to age, and dis-
appears in large specimens. The largest Afastigoptis in the "Siboga" material is 12 mm. long
and has the rostral process very thin and moderately short ; one of the smallest specimens
measures 4.3 mm. not including the very long rostral process which reaches the middle of the
eyes; both specimens are from Stat. 144. The descriptions by Kröyer, Bate, and myself,
and the figures published by Kröyer, Bate, and Chun of various stages of the Mastigopus
of 5. corniailum (and the very young stage named S. longirostris Bate) may be sufficiënt
for the present.

c. Acanthosoma (or Mysis-) S t a g e (PI. II, figs. ir — 1/). — Together with a single
Mastigopus 3 specimens of Acatithosoma were found in the Plankton material, and for various
reasons, viz. length of rostrum, shape of the eyes and of the exopod on the uropods, they
must belong to this species. The rostrum (fig. ie) is about half as long again as the carapace
in the median line, with many fine spines. The carapace (figs. ie — id) has four pairs of long

21

processes; the first pair are in reality the supra-orbital spines which are nearly as long as the
eye-stalks and have several fine spiniform processes. Second pair project from the antero-lateral
angles; each process has about six long or very long branches, and on the distal part some
small spines. Third pair a little behind second pair but much higher upwards on the vaulted
carapace, and these processes are probably homologous with the gastro-hepatic spines ; fourth
pair originate considerably behind the middle of the carapace somewhat above its lateral margin ;
each process of these tvvo pairs has about four moderately long branches on its proximal third,
and some spines on the distal portion. Each of the five anterior abdominal segments (figs. i c
and i e) has three very long processes, one dorsal and one on each lateral margin, and these
processes are spiniferous and with branches towards their base; sixth segment has only the
dorsal process. Distal joint of the eye-stalks about half as long as the median line of the
carapace ; the eyes are large (fig. i d), considerably deeper than broad and placed not quite
vertical on the stalk. The antennular peduncles are not much shorter than the carapace, two-
jointed, with first joint more than three times as long as the second ; upper flagellum about half
as long as the peduncle, two-jointed, while the lower flagellum is a mere knot. The antennal
squama (sg.) is very narrow and a little longer than first antennular joint, with the distal marginal
spine extremely long and projecting uncommonly remote from the end of the squama. Third
maxillipeds and all five pairs of thoracic legs with both endopod and exopod; in the two
posterior pairs the exopod is about twice as long as the endopod. All pleopods are very con-
spicuous, each consisting of a single, very oblong joint. The uropods (fig. i ƒ) are long and
very slender; the peduncle has the outer angle produced into a long, spiniform process; the
exopod has the ciliated part of the outer margin a little more than twice as long as the naked
part, and at the end of the latter is found a somewhat long, spiniform process. The telson is
peculiarly shaped; its proximal third is broad, subrectangular, with a spine at each postero-lateral
angle; then it tapers rapidly to the middle, while its terminal part is again a little broader
and deeply divided into two branches; a pair of dorsal spines are seen considerably from the
end, and each branch has a small spine above and terminates in a very long and strong spine. —
Length without rostrum 2.5 — 3.2 mm.

Remarks. — As already stated, the only valid specific differences between S. semi-
nudus and 6". comiculum hitherto found are in the structure of the male petasma. The males
of the two species are instantly separated by the shape and equipment of the lobus armatus,
which in 5. seminudus is more slender with hooks along- the whole inner margin and no hook
near the distal end of the anterior side, while in 6". comiculum the lobe is proximally consider-
ably thicker with about three conspicuous hooks along the proximal part of the inner margin,
some quite small hooks at the terminal margin, an extremely big hook on the front side near
the end, but no hooks along the distal half of the inner margin to near the end. Furthermore
lobus connectens has in 5. comiculum no hooks on its anterior side, the lobus terminalis a
somewhat other shape than in 5. seminudus, and processus ventralis a higher number of teeth
at the distal margin. Judging from the size of adult specimens of both species S. comiculum
is somewhat to considerably larger than S. seminudus.

A male specimen from the Bay of Bengal received from the Museum in Calcutta as

22

S. rubro-gttttatus Wood-Mason belongs to S. corniculum ; which consequently is found at least
in the more western part of the Indian Ocean. 5". corniculum Kr., which was established on
specimens in the Jl/asiigoptts-stage from the tropical Atlantic, is common at least in the northern
subtropical area of that ocean, and judging from its Mastigopus it is known from lat. 420 N.
to lat. 300 S. In 1896 I wrote that I had seen specimens of S. corniculum from the Indian
Ocean and ranging into the Pacific to the Matelota island and to lat. i6°7o'N., long. i32°E.;
these specimens were either Masiigopus-forms or quite young animals with black eyes, but as
the adult males from the "Siboga" belong to the hitherto unknown species S. semimidus, and
as I think it nearly impossible to separate young specimens or Masiigopzis-stages of this species
from those of S. corniculum, the statements quoted on the distribution in the Indian Ocean
and the Pacific show only the distribution of this tribe consisting of two species, and at least
the major part or perhaps nearly all of the specimens in question belong in all probability to
5. seminudus.

Species of Group II.
8. Sergestes orientalis n. sp. PI. II, figs. ia — 2q.

Stat. 2>7- March 30—31. Sailus Ketjil, Paternoster islands. 27 m. and less. Surface. 5 Mastigopus.
Stat. 40. April 2. Anchorage off Pulu Kawassang, Paternoster islands. 12 m. Tovvnet. 2 Masti-
gopus.
Stat. 66. May 7 — 8. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer.

8 — 10 m. Plankton. 1 young specimen, 7 Mastigopus.
Stat. 96. June 27. South-east side of Pearl bank, Sulu-archipelago. 15 m. Townet, surface.

2 Mastigopus, 1 Acanthosoma, 1 Elaphocaris.
Stat. 106. July 4. Anchorage off Kapul-island, Sulu-archipelago. 13 m. 1 Mastigopus.
Stat. 118. July 13. Lat. i°3S'N., long. i24°28'.2E. Hensen vertical net, from 900 m. to

surface. 1 specimen.
Stat. 125. July 18—19. Anchorage off Sa wan, Siau-island. 27 m. Plankton. 1 Mastigopus.
Stat. 128. July 22. Lat. 4°27'N., long. I25°25'.7E. 1645 m. Hensen vertical net, from 700 m.

to surface. 2 Mastigopus.
Stat. 131 — 133. July 25. About lat. 50 $6'. 7 N., long. I26°25'E. Plankton. 1 Mastigopus.
Stat. 141. August 5. Lat. i°o'.4S., long. I27°25'.3E. 1950 m. Hensen vertical net, from

1500 m. depth to surface. 1 specimen. 1 Mastigopus.
Stat. 143. Aug. 7. Lat. i°4'.5 S., long. i27°52'.6E. 1454 m. Hensen vertical net, from 1000 m.

to surface. 4 specimens, 1 Mastigopus.
Stat. 144. Aug. 7 — 9. Anchorage North of Salomakiee-(Damar-)island. 45 m. Plankton. 4

Mastigopus.
Stat. 146. Aug. 9. Lat. o° 36' S., long. I28°32'.7E. 512 m. Tovvnet, surface. 1 specimen, 1

Mastigopus.
Stat. 148. Aug. 10. Lat. o° if.6 S., long. I29°I4'.5E. 1855 m. Hensen vertical net, from

IOOO m. depth to surface. 8 specimens, 1 Mastigopus.
Stat. 157. Aug. 15 — 16. Lat. o°32'.9S., long. I30°I4'.6E. 45 m. Plankton. 6 Mastigopus.
Stat. 168. Aug. 22 — 23. Anchorage North of Sabuda-island. 63 m. Townet, surface. 2 Mastigopus.
Stat. 172. Aug. 26 — 28. Gisser, anchorage between this island and Ceram-Laut. 18 m. Plankton.

1 Mastigopus.
Stat. 177a. Sept. 1. Lat. 2°3o'S., long. I29°28'E. Townet. 1 young specimen, 20 Mastigopus

and Acanthosoma.
Stat. 185. Sept. 12. Lat. 30 20' S., long. I27°22'.9E. Hensen vertical net, from .1536 m.

depth to surface. 4 specimens, 4 Mastigopus.

23

Stat. 189a. Sept. 12. Lat. 2°22'S., long. 1260 46' E. Townet. 2 Mastigopus.

Stat. 194—197. Sept. 15. Lat. i° 53'-5 — i°45'-3 S., long. 1260 39— 127°8'.3 E. Plankton. 3

Mastigopus.
Stat. 203. Sept. 19. Lat. 30 32'.5 S., long. i24°is'.5E. HENSEN vertical net, from 1500 m.

depth to surface. 8 specimens, 1 Mastigopus, 1 Acanthosoma.
Stat. 206 or 207. Sept. 21. Buton-strait. Surface. 3 Mastigopus.
Stat. 220. Nov. 1 — 3. Anchorage off Pasir Pandjang, west coast of Binongka. 27S m. Townet,

surface. 1 Mastigoptis.
Stat. 225. Nov. S. 5700 m. N. 2790 E. from Southpoint of South-Lucipara-island. 894 m.

Horizontal cylinder. 1 young specimen, 1 Mastigopus.
Stat. 230. Nov. 14. Lat. 3°58'S., long. i28°2o'E. Hensen vertical net, from 2000 m. depth

to surface. 7 specimens.
Stat. 245. Dec. 3. Lat. 4°i6.sS,, long. I30°I5'.8E. Townet. 7 specimens.

a. Adult Specimens (PI. II, figs. 2a — 2k). — Closely allied and similar to S. Ed-
wardsii. The carapace is moderately compressed; its rostrum is rather short, directed forwards
and somewhat upwards, nearly obliquely triangular, acute and even acuminate, as the distal
part of both the upper and the lower margin is a little concave. The supra-orbital spines are
somewhat small, acute; the hepatic spines well developed. The gastro-hepatic groove is well
developed, the cervical groove not discernible. The eyes are somewhat small, scarcely depressed,
only a little broader than the stalk ; the stalk is rather long in proportion to the eyes, as the
outer margin of its distal joint is about half as long again as the eyes. The peduncles of the
antennulae are somewhat long; first joint moderately narrow with the distal half of the outer
margin convex ; second joint is rather slender, a little shorter than the third joint which is
slender, similar in both sexes and about as long as the first. The lower flagellum of the male
with its clasping organ is shown in fig. 26 from the outer side; a description is scarcely
needed, but it may be remarked that the very long, strong and much curved spiniform
process reaches about to the middle of the 6-jointed part of the flagellum beyond the base
of the process. The antennal squama reaches beyond the middle of third antennular joint; it
tapers considerably to the narrow end so that the terminal margin is quite short, while the
outer terminal spine is very distinct. Third pair of maxillipeds is very long, a little more than
twice as long as the carapace, somewhat more than two and a half times as long as first
thoracic legs and more than half as long again as third pair of thoracic legs; the four proximal
joints are much thickened, third and especially fourth joint besides depressed so that the latter
joint, seen from above, is considerably broader than visible on fig. 2c, and this joint has about
a dozen fine bristles of very different length along the inner margin (not visible on the figure)
and some five short bristles along the outer margin ; fifth and sixth joints are much depressed
— in reality compressed but turned so that they look as depressed — with the outer and
inner margins 'nearly parallel ; fifth joint has about its distal fourth cut off as a subjoint, its inner
margin has a number of fine bristles and three long, moderately slender spines, and on the
lower surface near the outer margin a smaller number of bristles. Sixth joint is divided into
4 subjoints, the two proximal distinctly longer than the two others, and the second a little
longer than the first, and each of the two distal subjoints is again subdivided into two joints
subequal in length; thus in all 6 subjoints are found. Sixth joint has 2 spines on the end, the

24

inner long and strong, the other thinner and distinctly or very considerably shorter; on the
inner margin first and second subjoints have each on the end a very long and strong spine,
fourth subjoint a considerably smaller spine; on the inner margin of all subjoints together is
found in the leg exhibited (fig. 2 c, a.) in all 37 spines — the terminal not included — extremely
different in size and several among them very small ; on the lower side near the outer margin
is found a long, thin spine near the end of first and second subjoints, and sometimes a cor-
responding but quite small spine is observed on fourth subjoint. The thoracic legs are slender;
first pair (figs. 2ci and 2 e), as already stated, small, with a conspicuous, oblong, curved, acute
tooth or robust spiniform process on the dorsal side of third joint, and the terminal joint not
subdivided. Second pair have on the dorsal side of third joint a curved acute process which
is longer than in first pair; third pair, when stretched forwards, reach about the end of the
antennular peduncle. Fourth pair (fig. 2 f) is a little shorter than the first, with the two distal
joints somewhat narrow; fifth pair is unusually short, and their two distal joints narrow with
rather few natatory cilise. The exopod of the uropods tapers from somewhat from the base to
the narrowly rounded end ; its outer margin is ciliated in the whole length and feebly concave
from somewhat from the base to the end.

The branchiae above the thoracic legs are long; above third pair a branchia and a
lamella; above fourth pair two branchiae, the first slightly shorter than that above third pair,
the second somewhat shorter and considerably narrower than the first, but of the same regular,
oblong shape and very well developed.

The petasma (figs. 2g — 2t and fig. 2k) differs extremely from that in any species of
group I. Pars externa is small, its lamina {lam.') is very oblong, more than half as long again
as broad and broadest in front, with the posterior two-thirds of the outer margin concave and
the anterior third convex; processus uncifer {pn.) is reduced, conspicuously less than half as long
as lamina externa, and its terminal part rounded without any incision. Pars media is extremely
broad; processus basalis is a large, triangular plate a little broader than long with the end
narrowly rounded. Processus ventralis {pv.) is quite minute, oblong-triangular, with the distal
part very narrow. Lobus armatus {la.) is short, extremely broad and divided by a short but
very broad terminal incision into two diverging branches; several small hooks are observed at
the inner margin of the inner branch, and numerous small hooks on the anterior side and at
the end of the outer branch. Lobus connectens {lc.) is moderately short and very thick with
the end broadly rounded ; it has many conspicuous hooks on the posterior side and along the
inner margin. Lobus terminalis {II.) is moderately short, very slender, subcylindrical, with a
single very large hook on the obtuse end. Lobus inermis (//.) is larger than any of the other
lobes, directed forwards and much inwards, very thick to the broad, very obtuse end, and without
hooks. At the base of lobus inermis is found a very slender lobe terminating in a very large
hook; as no corresponding ramification is found in the preceding forms it is named lobus acces-
sorius {lac). Pars astringens («.) is small, but the coupling hooks along its inner margin are
well developed.

Length of a large male 19 mm., of a male from the Chinese Sea 20 mm., of a
female 16 mm.

2.5

b. Mastigopus- Sta ges (figs. 2/ — 2«). — The stages of this species are scarcely discer-
nible from those of S. Edwardsiï, which have been described and figured by Kröyer and Bate
as .S. oaclatus Kr., and a young stage by Kröyer as S. brachyorrhos Kr. ; besides these stages
were mentioned by me in 1896. A large Mastigopus (from Stat. 144) is 10.8 mm. long; the
long eye-stalks with the large, very oblique eyes are in the main as in the much younger
animal shown in fig. 2/; the rostrum is considerably produced, proportionately about twice as
long as in the adult; the terminal joint of third pair of maxillipeds (fig. ini) is divided into
4 subjoints, and each of the two distal subjoints shows a feeble transverse line, thus a rudim-
entary division into two joints, while the equipment with spines of all 6 subjoints differs widely
from what is found in the adult. The abdominal segments without dorsal spines, excepting sixth
segment which has a minute spine on the upper terminal angle. The outer margin of the
exopod of the uropods ciliated nearly to the base, thus almost as in the adult; telson long and
nearly as in the adult. — Fig. 2 / exhibits the carapace with eyes, antennulae and antennal
squama of a small specimen measuring (without rostrum) 4.3 mm. length; it is seen that the
rostral process is more than one-third as long as the carapace in the median line, and that
the supra-ocular and hepatic spines are rather long. The long eye-stalks with the very oblique
eyes show the shape peculiar to this form. The antennular peduncles are only two-jointed, the
first joint is long, very slender from the end to a little from the base, and this basal part is
widened and produced into a triangular, acute process ; the lower flagellum is a minute joint.
The abdomen has in this specimen a very distinct spine at the upper hind angle of each of
the three posterior segments; the telson is short, only a little longer than in the still younger
form mentioned below and similar in shape ; the outer margin of the exopod of the uropods is
ciliated in 8/9 of its length, and at the end of the short, naked basal part a quite rudimentary
spine is seen. — A still younger Mastigoptis is only 3.3 mm. (rostrum not included); its rostrum
and the supra-ocular and hepatic spines are still longer than in the preceding larva ; second
abdominal segment has a minute dorsal spine considerably before the end, third and fourth
segments each a moderately long dorsal spine a little from the end, fifth and sixth segments
each a similar spine from the hind angle. The telson is short (fig. 2;/), seen from above shaped
in the main as in the Acanthosoma-s,X.a.gz (fig. 2q\ consequently broad from the base to con-
siderably beyond the middle, then somewhat narrowed, with each posterior angle produced in
a short process terminating in a spine ; the outer margin of the exopod of the uropods (fig. 2 u)
is ciliated in scarcely 5/0 of its length, and the naked part terminates in a spine.

c. Acantkosotua- (or Mysis-) S t a g e (figs. 20 — 2q). This stage, which has never been
described, is somewhat similar to that of 5. semzmtdus, but differs in various features. The
rostrum is about as long as the median line of the carapace, with a number of fine spines.
The carapace has the same four pairs of processes as in 5. semzmtdus and besides a process
posteriorly in the median line. The first pair of processes, in reality the supra-orbital spines,
are very long, more than half as long as the rostrum, curved, with some fine spines. The three
other pairs are not half as long as the first pair; the two lateral pairs have lateral branches
near the base and more distally a few fine spines. The posterior process originates at the hind
margin of the carapace, is directed forwards and a little curved, about half as long as the

I00

SIBOGA-EXPEDITIE XXXVIII.

26

rostrum. The abdominal segments have the same dorsal and lateral processes as in S. semi-
nudus, but first segment has besides (fig. 2 o) a pair of sublateral, rather short and subcylindrical
protuberances a little from its anterior end. The eye-stalks are distinctly shorter than in the
Mastigopus shown in fig. 2/, but thicker towards the large, thick, oblique eyes. The antennular
peduncles (al) without any articulation ; the upper flagellum conspicuously less than half as long
as the peduncle, unjointed, and the lower flagellum short though much longer than in 5. semi-
■nudus. The antennal squama (sq.) very narrow, with the distal marginal spine extremely long
and originating proportionately considerably behind the end of the squama. The telson (fig. 2q)
is short, scarcely twice as long as broad ; its distal part is narrowed and the end strongly
emarginate, with a spine from each much produced lateral angle, but no other spines are found
on the telson. The exopod of the uropods has its outer margin ciliated in somewhat more than
3/4 or in almost 4/5 °f lis length, and a rather long spine is seen at the end of the naked part.
Length without rostrum 3 mm.

Remarks. — S. oricntalis is so closely allied to S. Edivardsii Kr. that to begin with
I had not separated it, but a closer examination gave the result that the petasma differs con-
siderably from that in the Atlantic species. As the petasma in the latter form was unknown
I thought it nearly necessary to insert a drawing (PI. II, fig. 5 a) for comparison. It is seen
that in S. Edwardsii processus ventralis (pv.) is still much smaller and subcylindrical ; the outer
branch of lobus armatus (la.) is long and moderately slender, and the long lobus inermis (li.)
is longer and only half as thick as in 5. oricntalis. It may be noted that I have inspected
the petasma in some specimens of both species and found the differences constant. I have not
been able to find other absolutely valid specific differences between the two forms; yet it may
be mentioned that S. Edivardsii is frequently somewhat larger than 5. oricntalis, that the two
terminal spines on sixth joint of third maxillipeds are subequal in length and frequently in
thickness in S. Edwardsii, while in 5. oricntalis they differ generally more conspicuously in
size, and in some specimens the spine on the angle is twice as long as the other ; furthermore
fourth subjoint of sixth joint in third pair of maxillipeds has in S. Edwardsii a moderately or
rather long spine on the lower side near the outer margin, while in S. oricntalis this spine
is either quite short or wanting.

Adult and subadult specimens of S. Edwardsii and .S. oricntalis differ from all other
species of group II in having sixth joint of third pair of maxillipeds divided into 6 subjoints,
while all the other species hitherto known have only 4 or 5 subjoints, and besides in having
the entire outer margin of the exopod of the uropods ciliated, which is not the case in any
other species of the genus.

Distribution. — The Copenhagen Museum possesses male specimens of S. oricntalis
from a place a little south-east off South Africa, and from the Chinese Sea at lat. iq°i4'N.,
long. 11 6° 6' E. (Capt. Andréa). No male of this species has been taken in the Atlantic, while
5. Edivardsii has not been discovered in the Indian Ocean or the Pacific.

27

Sicyonella Borradaile (Aphareocaris Calm.).

This characteristic genus has been somewhat curiously treated. In 1875 the Russian
zoolocist PAULSon established the genus Aphareus on a single species, A. inermis Pauls., from
the Red Sea ; it was referred to the family Penaeidse. As Paulson's paper is not only rare but
published in the Russian language, G. Nobili in 1906 fortunately translated the original description
of Aphareus into French and reproduced two of the figures; besides he suggested that the
o-enus ought to be referred to the Sergestidse. In 19 10 Borradaile established the genus Sicyo-
nella on a new species, 5". maldivensis Borr. ; he described the animal and added two figures,
but he did not perceive that the genus was identical with Paulson's Aphareus, and he referred
it to the subfamily Sicyoninae, of the family Penaeidse, which was rather unfortunate, and the
worst result of his classification is the misleading generic name. In 191 3 W. T. Calman proposed
the name Aphareocaris for Aphareus Pauls. which was preoccupied, but overlooked that the
genus was identical with Sicyonella Borrad., and according to the rules of priority the latter
name must be applied. Calman referred his form A. elegans Calm. to the family Sergestidae,
pointed out several important characters as to which the genus agrees with Sergestes, and
besides three eenene differences between it and Sergestes-, amoncr these the character based on
the male antennula? cannot be maintained, as later seen by Calman himself. He described a
single species, A. elegans, from the Torres Straits, and added 16 figures; his investigation and
his figures are so good that I have found it unnecessary to redescribe the type, its appendages
and branchiae or to draw new figures of the entire animal or most of its appendages. — In
19 14 Calman published an additional note, as Dr. H. Balss had drawn his attention to the
similarity between Aphareocaris Calm. and Sicyonella Borrad. He discussed the differences
between Borradaile's statements and his own in 19 13, suggested that his A. elegans Calm.
most probably had been established on an immature specimen, and that it must be considered
as a synonym to Sic. maldivensis Borrad., but whether this conclusion may be safe is to be
discussed later on. Finally Calman published a new figure of the petasma of the adult Sic.
maldivensis, which renders it possible to recognize this species with absolute certainty.

Sicyonella Borrad. differs from Sergestes in the following characters. 1) The first pair
of legs have a well developed chela which is wanting in Sergestes; 2) second an third pairs
of legs have the chela much more developed with the fingers much longer in proportion to
the hand than in Sergestes; 3) the two last pairs of legs have seven joints, while in Sergestes
the seventh joint is absent; 4) telson has some pairs of dorsal spines, but no spines in Sergestes;
5) the processus ventralis of the male petasma is cleft into two very long branches, while it is
undivided in Sergestes. In all these characters, excepting perhaps the last mentioned, Sicyonella
stands nearer to the Penaeidae than Sergestes. The main differences between the Penaeidae and
Sergestes-Sicyonella together with figures illustrating most of the generic features of Sicyonella
are to be looked for in Dr. Calman's paper.

Three species have been established in the literature, among which Sic. maldivensis
Borrad. can be determined with certainty by the aid of Calman's figure of the petasma in his

28

second paper, while it remains uncertain whether S. elegans Calm. is a valid species or a
synonym, as according to Calman's figures in his first paper its petasma seems to differ more
from that in the adult Sic. maldivensis than might be expected between petasma in the immature
and that in the adult male of the same species. It cannot be settled with any certainty whether
Sic. inermis Paulson is identical with Sic. nialdivensis Borrad. or a separate species before new
specimens have been gathered in the Red Sea.

In the "Siboga" material 2 species are found, viz. Sic. maldivensis Borrad. and a fine
new species; of the latter I have fortunately also a good material from the Gulf of Siam.

1. Sicyonella maldivensis Borrad. PI. II, figs. \a — \g.

1910. Sicyonella maldivensis Borradaile, Trans. Linn. Soc. London. 2n|l Ser. Zool., Vol. XIII,
pt 2, p. 259, PI. 16, fig. 3, ia.

191 3. (?) Aphareocaris elegans Calman, Journ. Linn. Soc. London, Zool. Vol. XXXII, p. 219,

PI. 16, figs. 1 — 16.

1914. Sicyonella maldivensis Calman, Ann. Mag. Nat. Hist., ser. 8, Vol. XIII, p. 259, figs. A, B.

Stat. 164. August 20. Lat. i°42'.5 S., long. i30°47'.5 E. 32 m. Sand, small stones. Dredge.

2 females.
Stat. 213. Sept. 26 — Oct. 26. Saleyer-anchorage and Surroundings. Depth up to 36 m. Coral-

reefs, mud and mud with sand. 2 males, 1 female.
Stat. 323. Febr. 24 — 25. Sangkapura-roads, Bawean-island. 12 m. Mud. 11 small specimens.

Description. — Dorsal crest of the carapace with two acute teeth, not including
the short, acute rostral process. Eyes distinctly larger in the male (fig. \d) than in the female
(fig. 4<5); in the female the distance from the base of the long second joint of the eye-stalk to
the end of the cornea is somewhat more than two and a half times as long as the breadth
of the cornea, while in the male the same distance is only somewhat more than twice as long
as the breadth of the cornea. The antennular peduncles in the female moderately long; the
inner margin of its two distal joints combined nearly as long as the same margin of first joint;
second joint rather broad, not quite twice as long as broad, and its inner margin nearly one-
fourth as long again as third joint, which is somewhat slender. In the male the two distal
joints combined are considerably longer than in the female, with their inner margin very con-
spicuously longer than that of first joint; second joint is a little longer and proportionately a
little narrower than in the female, and its inner margin is slightly shorter than third joint, which
is distinctly thicker and considerably longer than in the female. The lower flagellum in the
male (fig. \c) has the proximal portion widened with the lower margin somewhat convex, while
the upper margin is very concave excepting towards both ends of the widened portion, so that
in reality only the short proximal and the longer distal parts of the portion with the lower
margin convex are thick ; the upper margin of the curved portion is equipped with a little more
than twenty spines which are long on the thick parts, shorter and considerably less closely set
on the middle part of the concavity. — The antennal squama reaches in the female about to
the middle of third antennular joint, in the male rather little beyond second joint.

First pair of legs moderately slender; fifth joint (fig. 4 «f) is somewhat shorter than the
chela and has on the lower side a peculiarly shaped group of pectinate spines answering to a

group in Ser gestes-, the chela is not fully six times as long as broad, with a longitudinal row
of thin spines on the subproximal part of the lower side near the margin; the hand is a little
more than half as long again as the movable finger. Third pair of legs much longer and much
more slender than first pair; the chela in an adult female is about fourteen times as long as
broad, and the hand is scarcely three times as long as the movable finger.

The petasma (figs. 4 e — \g) is very characteristic. Pars externa is not small but peculiarly
reduced; its lamina (lam.) is more than twice as long as broad, with a very obtuse angle of
the outer margin somewhat before its middle ; processus uncifer (pu.) is less than half as long
as the lamina but broad, önly twice as long as broad, tapering towards the broadly rounded
end, which has no hook. Processus ventralis (pv.) is very long, divided to rather near the base
into twö branches, the longest situated behind the other, and covering its major part when the
petasma is seen from behind (figs. 4c and 4/"); the posterior branch has its distal half divided
again into two branches, the outer somewhat slender, straight and terminating in a hook, the
inner somewhat longer, rather curved and considerably broader than the other, and its distal
part is expanded outwards forming a plate which has one extremely large hook and a small
hook at the outer margin; the anterior branch of processus ventralis is moderately slender,
but nearly its distal fourth is expanded essentially and very strongly outwards, constituting a
transverse plate which has a row of small hooks at the inner margin and a few similar hooks
at the terminal margin. Lobus armatus (la.) projects far beyond the insertion of the processus
ventralis and about from the middle of the capitulum; it is directed wholly outwards, thus
nearly vertical on the main direction of pars media; it is broad, rather long and tapers con-
siderably beyond its middle to the obtuse end; an extremely large hook is seen on its distal
margin somewhat from the end, and five smaller hooks near the oblique terminal margin.
Along the inner margin of the sub-proximal half of the capitulum is found a somewhat feeble
expansion with about six hooks near the margin (fig. $g), and it terminates in a rudiment of
a lobe; the whole expansion may perhaps be considered as a kind of lobus accessorius. Lobus
terminalis (//.) is directed forwards, straight, somewhat short and slender, with several minute
hooks near the inner margin and at the end; at its base projects outwards and a little forwards
a triangle with the end obtuse and equipped with two hooks, and this triangle I consider as
the lobus connectens (Ie.). Lobus inermis does not exist. Pars astringens (fig. \e, a.) is broad,
moderately long, with a long row of coupling hooks.

Length of a male 23 mm., of a female 24 mm.

Remarks. — Calman's figures of the petasma taken from one of Borradaile's types
of Sic. maldivensis show that the "Siboga" specimens belong to the species described by
Borradaile. But it seems to me somewhat doubtful that Sic. (Aphareocaris) elegans Calm. is
the young male of Sic. maldivensis, because the petasma, according to Calman's figures, must
be so different from that in Sic. maldivensis that I cannot think it to be a not fully developed
organ of the latter species. The differences between Sic. maldivensis and the following species
are pointed out later on.

Distr ibu tion. — Borradaile writes: "Specimens were taken throughout the Maldives
and in Cargados Carajos in various depths".

3Q

2. Sicyonella antennata n. sp. PI. II, figs. $a — 5c; PI. III, figs. \a — 1/.

Stat. 258. Dec. 12 — 16. Tual-anchorage, Kei-islands. 22 m. Lithothamnion, sand and coral.

1 male, 1 female.
The Copenhagen Museum possesses 14 specimens taken by Dr. Th. MORTENSEN in 1900 in

the Gulf of Siam at various localities, viz. between Koh Mesan and Cape Liant, 9fathoms;

Koh Kahdat, 4 — 5 and 5 fathoms, and South of Koh Mak, 5 — 6 fathoms.

Description. — Rostrum with dorsal crest nearly as in Sic. maldivensis. Eyes distinctly
larger in the male (fig. 1 a) than in the female (fig. 1 ff) and larger than in the preceding species ;
in the female the distance from the base of the long second joint of the stalk to the end of
the cornea is distinctly more than twice as long as the breadth of the cornea, while in the
male the same distance is scarcely twice as long as that breadth. The antennular peduncles in
the female a little longer and distally more slender than in the female of Sic. maldivensis-, the
inner margin of the two distal joints combined is distinctly longer than that margin of first
joint; second joint a little longer than in Sic. maldivensis, with the inner margin slightly longer
than, or as long as, third joint. In the male the two distal peduncular joints are elongated,
the inner margin of both joints combined only somewhat less than twice as long as the inner
margin of first joint; third joint proportionately slender and considerably longer than the second.
The lower flagellum in the male (fig. 5*7) in the main as in Sic. maldivensis, yet differing in
having a much lower number of spines on the concave margin.

First pair of legs (fig. 5Ó) a little more slender than in Sic. maldivensis; the chela is
shorter than fifth joint, a little more than six times as long as broad, and the hand is some-
what more than half as long again as the movable finger. Third pair of legs still more slender
than in Sic. maldivensis-. the chela of a female (fig. 5 f) is about sixteen times as long as the
breadth of the hand at its middle, and the hand is somewhat more than three times as long
as the movable finger.

The petasma (figs. \d — if) differs strongly from that in Sic. maldivensis. The pars
ëxterna is about as large as in Sic. maldivensis, but somewhat differently shaped ; the lamina
externa {lam.) is twice as long as broad, with the obtuse angle on the outer margin somewhat
before the middle; processus uncifer (pit.) is considerably more than half as long as the lamina,
narrow from the base to the rounded end which has no incision. A processus basalis is not
developed. Processus ventralis (pv.) is very long, as in Sic. maldivensis divided into two branches,
but the proximal undivided part is more than one-third as long as the whole process; the
posterior branch is broad at the base, but tapers rapidly towards the middle, and distally it is
divided into two secondary branches (fig. ie), the inner nearly shorter than broad with a row
of small hooks along the terminal margin, while the other secondary branch is generally longer,
more narrow and directed much outwards, with some small hooks near the end; the anterior
branch of processus ventralis is considerably shorter than the posterior, narrow excepting towards
the base which is extremely expanded, and the terminal part of the branch is somewhat widened
and rounded, with a good number of minute hooks on both sides. The capitulum, or distal
main portion of pars media excepting proc. ventralis, is so different from that in Sic. maldi-
vensis and from those in species of Sergestes known to me that I cannot interpret all the lobes

3i

with certainty. Along the most proximal part of the inner margin a narrow area with a good
number of hooks is seen (fig. ie), probably a remnant of a lobus accessorius a little less developed
than in Sic. maldivensis. This area is found on a moderately thick, very oblong body, which
near the middle of the posterior side has two rather slender, subcylindrical lobes directed back-
vvards and outwards, and each terminating in an extremely large hook; the outer of these
processes is not improbably lobus armatus {ld.), but the other must be an accessory lobe (lac).
More distally on the posterior side of capitulum is seen a somewhat long, very slender lobe
directed mainly forwards and terminating in a rather large hook; this lobe (Ie.) may answer to
lobus connectens in Sergestes. The capitulum terminates in a long, gradually tapering lobe,
lobus terminalis (//.), which is nearly spirally twisted and has on one side a very large number
of minute hooks ; at the base of lobus terminalis a very short, truncate lobe projects forwards
and inwards and terminates in a very large hook; this last-named protuberance is perhaps lobus
inermis (? li.). — Pars astringens (fig. i d, a) is very broad, with the usual marginal row of
coupling hooks.

Length of a large male 25 mm., of a small male 18.5 mm.; a very large female measures
31.5 mm. in length, but adult females are sometimes considerably smaller, about 25 mm. long.

Remarks. — The male is instantly distinguished by the elongated antennular
peduncles and the peculiar petasma; the female can be separated from that of Sic. maldivensis
by the eyes, the two distal joints of the antennular peduncles, and the relative length of the
antennal squama.

Distribution. — The localities hitherto known are enumerated above immediately
after the "Sibora" station.

'&■■

Acetes H. M.-Edw.

Diagnosis. — Body rather slender; general aspect nearly as in Sicyonella. Carapace
anteriorly with a short crest, armed with a single denticle or most frequently with two denticles,
and produced into a short rostral process. Supra-orbital and hepatic spines vvell developed.
Antennulse with second joint in the peduncle somewhat short; third joint in the female con-
siderably, in the. male from considerably to twice or almost three times longer than the second ;
the lower flagellum in the male with the clasping organ as in Sergestes. Antenna; as in Sergestes.
Mandibles (PI. III, fig. 2e) mainly as in Sergestes-, palp 3-jointed, with first joint very short,
second long and slender. Maxillulae (PI. III, fig. 2/) with both lobes well developed, but without
palp. Maxillse (PI. III, fig. 2g) with only a single undivided lobe, while the palp (p.) is well
developed, somewhat broad. First pair of maxillipeds (PI. III, fig. 2/1) differ considerably in
shape from those in Sergestes-, the distal lobe is long, very oblong-triangular with the end sub-
acute; the palp is wanting, but exopod (ex.) and epipod (ep.) are well developed. Second pair
of maxillipeds (PI. III, fig. 22') have the third joint long, much longer than the second and
about as long as the fifth, which is very long, while the sixth is short and slender; exopod
wanting; epipod and podobranchia well developed. Third pair of maxillipeds slender and long,
but always somewhat or considerably shorter than third pair of legs; each leg with only six
joints, as second joint is fused with the third; the two distal joints are undivided (PI. III, fig. 2k);

32

above the maxilliped a single pseudobranchia is found. First pair of thoracic legs much shorter
than third maxillipeds, terminating (PI. III, fig. 2 /) in a quite short, but not rudimentary chela,
and its fingers have a kind of brush near the end; sixth joint near the base and the preceding
joint near the end each with a close row of stiff, short setae nearly as those found in Scrgestes.
Second pair of legs considerably longer than the first and much shorter than the third pair:
second and third pairs slender and terminating in a very short chela agreeing with that of first
pair; all three pairs with seven joints, but without epipod or exopod. Fourth and fifth pairs
of legs wanting, but in the male a couple ot very thick protuberances are found, marked off
from the trunk by a suture or rather an articulation, directed mainly forwards and answering
to the coxae of a pair of legs, in all probability fifth pair (as already interpreted by Kishinoye) ;
these protuberances, which afford specific differences, are on the following pages described as
the genital coxae {ge. on PI. III, fig. 2 u). Above the thoracic legs four pleurobranchiae are
found, situated respectively above the three legs and above the place were the fourth leg,
which is wanting, would be placed, but I have found 110 rudimentary lamellar branchia behind
any of the four pseudobranchiae.

The petasma is much reduced as compared with those in Sergestes and Sicyonella ; pars
externa has no processus uncifer, pars astringens is frequently wanting, and the distal portion
of pars media has few ramifications, in most species only a processus ventralis and a capitulum
without special lobes.

Remarks. — The genus Acctes differs from Sergestes in several characters: the maxil-
lulse and the first maxillipeds without palp, the maxillse with undivided lobe, first pair of legs
with a short chela as the two following pairs, fourth and fifth pairs of legs wanting excepting
the coxae of (probably) fifth pair in the male, finally only five pleurobranchiae above third pair
of maxillipeds and the thoracic legs. — In the absence of two pairs of thoracic legs Acetes
agrees with Lucifer, but otherwise it is far removed from this peculiar genus and related to
Sergestes and Sicyonella.

The species of Acetes are very similar in general aspect, and all are rather small animals.
The eyes are nearly as large in the female as in the male. Specific characters found in both
sexes are few, viz. the number of denticles — one or two — on the rostral crest, the size of
the eyes, the relative length of the proximal thickened part of the upper flagellum of the
antennulae, the length of the ciliated portion of the outer margin of the exopod of the uropods
as compared with the whole margin, finally to some degree the second joint in third pair of
legs. The males show excellent specific characters in the relative length of third joint of the
antennulae, in the joints of the lower antennular flagellum and especially in the structure of its
clasping organ, finally in the structure of the petasma. In the females the ventral area at and
behind the base of last pair of legs affords most useful characters. The females are on the
whole somewhat or even considerably larger than the males.

The genus Acetes was established by H. Milne-Edwards in 1830 (Ann. Sci. Natur.
T. XIX, p. 350; PI. XI, figs. 1 — 9) on a species captured in the Ganges estuary and named
A. indicus. His representation is fairly good, but the description of the form is of course now
unsatisfactory. Fortunately his fig. 9, exhibiting the caudal fan, shows that the ciliated part of

33

the outer margin of the exopod of the uropods occupies scarcely one-third of the whole margin,
and supposing this feature to be correctly drawn we have here an excellent specific character,
which shows that A. indicus H. M.-Edw. differs from all the Asiatic forms seen by me and
besides from any other species described in the literature, excepting A. americanus Ortmann
from the Amazon estuary. The seas south and south-east of Asia evidently contain a good
number of species of the genus Acetes; their distribution seems frequently to be somewhat
restricted, and I think that A. indicus, taken in a place far distant from any other locality
tbr any Acetes seen by me or described by other authors, has never been rediscovered, but
ought to be looked for in the Ganges estuary.

It may be useful here to give a complete list of the species of Acetes hitherto established.
In 1859 H. Krüyer published an elaborate representation of a form which he referred to
Sergestes and named S: serrulatus Kr. ; he said he had found a couple of specimens among
"different Crustacea from the most northern Kattegat". Already in 1896 I pointed out that 5.
serrulattis Kr. in reality is an Acetes ; as the Copenhagen Museum possesses one of Kröyer's
two specimens I am now able to show that the Museum also possesses specimens from Java
and to redescribe the form; that the locality "the most northern Kattegat" is extremely wrong
does not require further comment. — In 1893 Ortmann (Ergebnisse der Plankton-Expedition,
Decap. und Schizop. Bd. II, G. b., p. 39, Taf. II, Fig. 2) established a species from the Atlantic,
A. americamis Ortm., taken in the 'estuary of the Amazon river. — In 1905 Kishinoye (Annota-
tiones Zool. Japonensis Vol. IV, pt. 4, p. 163) described and figured a fourth species, A. japo-
nicus Kishin., captured at various places in "the western parts of Japan" and in Korea; according
to the somewhat imperfect figure of the petasma and for another reason A. japonicus is allied
to but distinct from A. dispar n. sp., but whether it may be identical with A. chinensis n. sp.,
to be described later on cannot be settled, as the male of A. cliinensis n. sp. is unknown, and
Kishinoye's description of the female genital area is imperfect and the area not figured. —
In 1905 G. Nobili published a preliminary description and in 1906 a more detailed account
(Ann. Sci. Natur. Zool. 9. ser., t. IV, p. 23, PI. I, figs. 5- — -^e) of a new species, A. erythrcsns
Nobili, from the Red Sea; this species is larger than any seen by me, as the largest males
measured 33 mm. in length, and the description together with the rather poor figure of the
petasma is probably sufficiënt for recognizing the male.

In the literature the five species enumerated have been established by five authors, as
no writer has seen specimens of more than a single form. Of these five species only one, viz.
A. serrulatus Kr., is known to me, but I think that of the four others at least three are
recognizable. The "Siboga" has secured two species, both new and tolerably represented, and
besides a third form of somewhat doubtful quality. The Copenhagen Museum possesses two new
species respectively from the Brazils and La Plata, furthermore from the "Siboga" area and the
Gulf of Siam males and females of four species, viz. A. serru/atus Kr., one of "Siboga" forms, and
two other species; finally females of at least two species from the seas near China. The result
is that I can describe on the following pages no less than seven valid species represented in
both sexes, the female of an eighth species, male and female of a species of doubtful quality,
and the female of a variety or a new species.

SIBOGA-EXPEIHTIE XXXVIII. c

34

The species of Acetes live near the coasts, sometimes in the estuary of large rivers or
even in such rivers, generally in tropical and subtropical seas or countries, but yet going so
far northwards as to Korea. The different species are similar in general aspect and therefore a
careful investigation is necessary; probably there exist still a good number of undiscovered
forms, and the geographical distribution of each species seems to be somewhat or much restricted.
Judging from my material numerous specimens can frequently be taken in the same haul.

I. Species from Asia.

In all species from the seas south and east of Asia known to me the rostral crest has
two denticles behind the acute tip. In the female the antennal squama reaches to, or distinctly
beyond, the middle of third joint, but is far from reaching the end; in this sex the coxae of
third pair of legs have always a somewhat large, protruding tooth on the distal inner angle,
while the inner margin of the coxae is concave, and the proximal inner corner is produced into
a flat, rounded protuberance.

It is easy to give a key to the males, but as to the females it is preferred' to make it
somewhat imperfect, because one of the best specific characters is the shape and structure of
the genital area, which is next to impossible to deal with in a key.

Key to the Males.

A. Antennular peduncles with the third joint not much longer than in the
female, only about half as long again as the inner margin of second joint,
and shorter than the lower flagellum. The antennal squama reaches
rather considerably beyond the end of second antennular joint. (Petasma
has a well developed pars astringens with marginal coupling hooks).

a. Coxae of third lees with a triangailar tooth on the distal inner
angle. In the petasma the capitulum is scarcely one-third as long

again as processus ventralis A. vulgaris n. sp.

b. Coxae of third legs without any tooth on the distal inner angle.
In the petasma the capitulum is elongated, about twice as long

as processus ventralis Acetes sp.

B. Antennular peduncles with the third joint very much longer than in
the females, between twice and three times as long as the inner margin
of second joint and at least almost twice as long as the lower flagellum.
The antennal squama reaches scarcely or slightly beyond the end of
second antennular joint.

a. Trochanter of third pair of legs without any tooth on the inner
margin near its end.

a. Ciliated part of the outer margin of the exopod of the
uropods conspicuously shorter than the glabrous part.

o

5

f Clasping organ of the lower antennular flagellum
without any protuberance on the upper margin of
the curved part of the "branch". Petasma has a well
developed pars astringens with the row of marginal

coupling hooks A. Sibogcv n. sp.

ff Clasping organ of the lower antennular flagellum with
a conspicuous protuberance directed backwards from
the angularly bent upper margin of the "branch".

Petasma without pars astringens A. serrtilatus Kr.

p. Ciliated part of the outer margin of the exopod of the

uropods nearly or fully as long as the glabrous part . . A. dispar n. sp.
b. Trochanter of third pair of legs with a conspicuous triangular

tooth on the inner margin near its distal end A. spiniger n. sp.

Key to the Females.

A. Ciliated part of the outer margin of the exopod of the uropods con-
spicuously shorter than the glabrous part.

a. Trochanter of third pair of legs without any tooth on its inner

margin near the end. . A. vu/garis n. sp., A. Sibogce n. sp., and A. serrtilatus Kr.

b. Trochanter of third pair of legs with a conspicuous triangular

tooth on the inner margin just before the end A. spiniger n. sp.

B. Ciliated part of the outer margin of the exopod of the uropods nearly

or fully as long as the glabrous part. A. dispar n. sp., and A. chinensis n. sp.

i. Acetes vulgaris n. sp. PI. III, figs. 2a — 2r.

Stat. 4. March 9. Lat. 7°42' S., long. II4°I2'.6'E. Anchorage off Djangkar (Java). 9 m.

Coarse sand. 2 females.
Stat. 47. March 8 — 12. Bay of Bima, near south fort. 55 m. Mud with patches of fine coral

sand. 1 female.
Stat. 311. Febr. 12 — 13. Sapeh bay, east coast of Sumbavva. Up to 36 m. Mud and sand.

1 female.

The Copenhagen Museum possesses specimens from the following four localities, of which
two are within the "Siboga" area.

Surabaya, Java. Capt. AndkÉa. 1870. 2 males.

Cheribon, Java. Capt. AnüRÉa. 1870. 8 males, 5 females.

Malakka. Cand. pharm. MARIUS Jensen. Very large number of specimens.

Koh Kahdat, in the Gulf of Siam. Dr. Th. MoRTENSEN 25/I 1900. Large number of specimens.

M a 1 e. — Eyes a little larger than in the other species, their transverse diameter being
conspicuously more than half as long as the distal joint of the stalk with eye. Antennulae (fig. 2 a)
with the two distal joints of the peduncle a little longer and thicker than in the female (fig. 26),
taken together not much longer than the outer margin of first joint; third joint scarcely or at

36

most half as long again as the inner margin of second joint. Thickened part of the upper
flagellum about as long as the inner margin of second peduncular joint. Lower flagellum con-
spicuously longer than third peduncular joint, with 16 — 20 joints; its proximal part constitutes
a shaft for the clasping organ and is distinctly 3-jointed (fig. 2c/)\ the main "branch" of the
organ has its proximal 4-jointed part conspicuously and evenly curved, and the joints decrease
gradually in thickness; the fifth joint of this "branch" is nearly thicker than the fourth, with a
close row of 4 or 5 strong spines directed downwards and often somewhat outwards, while each
of the three preceding joints and the sixth joint has a single, much shorter spine, and the part
beyond fifth joint contains 8 — 12 joints; obliquely below and outside the base of the main
"branch" originates a single very strong and long, moderately curved spine, which reaches
almost the above-named row of spines. The antennal squama reaches always rather considerably
beyond the end of second antennular joint, but never to the middle of the third. Coxae of third
pair of legs (fig. 111) with a very distinct, triangular, acute tooth on the distal inner angle, and
the proximal inner corner is rectangular; the trochanter has 110 tooth near the distal end of its
inner margin. Genital coxae (fig. 211, ge.) obliquely triangular, a little longer than broad, distally
produced into a somewhat narrow, a little curved, subacute process. Exopod of uropods (fig. im)
somewhat more than four and a half times as long- as broad, and on the outer margin the
ciliated part occupies about two-fifths of the whole length.

The petasma (figs. 2p — 2r) is proportionately well developed. Pars externa (e.) is large,
about twice as long as broad, with the distal inner angle subrectangafiar, and more than the
distal third of the outer margin is somewhat convex. Pars astringens (a.) has a very long inner
margin equipped with coupling hooks. Pars media has its proximal portion free and rather
broad, with the basal margin somewhat concave so that two protuberances are formed, the
inner short, the outer much longer, oblong-triangular, and directed much outwards. Considerably
beyond the basal portion described is seen at the outer margin a piece connecting pars media
with the pleopod. The capitulum (c.) and processus ventralis (j>v.) are combined comparatively
small, not much more than one-fourth of pars media ; proc. ventralis is very robust, oblong-
triangular, a little curved, acute, without armature; the capitulum itself is distinctly but not
much longer than" proc. ventralis, scarcely even one-third as long again as the process, thick,
only a little more than twice as long as thick, much narrowed beyond the middle, but the
distal part is moderately thick though at its middle less than half as thick as the proximal
part, and broadly obtuse; seen from behind (fig. 2q) some quite small hooks are perceived near
the end, but seen from in front (fig. 2 r) two extremely large hooks are observed at the outer
margin beyond the processus ventralis, more distally a distinctly or much smaller hook, and at
the end some small hooks.

Length of a large male (from the Gulf of Siam) 24.5 mm., but sometimes the sex is
considerably smaller, a small male from Surabaya being only 17.3 mm. long.

Female. ■ — The sex differs from the male in the antennuke, the coxae of third legs
and, of course, the genital area. The peduncles of the antennulae (fig. 26) are somewhat shorter,
so that the antennal squama reaches distinctly beyond the middle of third joint; second and
third joints less robust than in the male and combined nearly as long as the outer margin of

first joint; third joint about half as long again as second; thickened part of the upper flagellum
longer than the inner margin of second joint; lower flagellum even a little longer than the two
distal peduncular joints combined, in a good-sized specimen with about 24 joints. Coxee of third
pair of legs (iïg. 2 o) with the inner margin concave, as the proximal inner corner is produced
mainly inwards as a small, rounded plate; trochanter without any tooth near the end of the
distal inner margin.

The genital area is characteristic (fig. 2 o) ; inside the small plate from the proximal angle
of each coxa is seen a rounded protuberance, and somewhat behind these two protuberances
a deep, transverse, distinctly procurved furrow runs across the surface of the body separating
the two posterior thoracic segments, and the median part of the surface behind the furrow has
a conspicuous impression.

Length a good-sized female from the Gulf of Siam 27 mm., while a very large specimen
from Cheribon (Java) measures 33 mm.

Remarks. — As this species has been taken at more localities and in much larger
numbers than any of the other forms, I give it the name A. vulgaris. It has amnities to
" Acetes sp." to be mentioned presently and to A. Sibogce n. sp., but not to any other species.

Acetes sp. PI. III, fig. 3 a.

Stat. 47. March 8 — 12. Bay of Bima, near south fort. 55 m. Mud with patches of fine coral
sand. 1 male, 2 females.

In a bottle with 16 specimens of both sexes of A. Sibogce and 1 adult female of A.
vulgaris I found 3 specimens, 2 among them adult, which are closely to A. vulgaris but show
a few differences indicating a development between A. vulgaris and A. Sibogce.

The Male, which is 23 mm. long, agrees with A. vulgaris as to the length of the
joints in the antennular peduncles, and differs consequently from A. Sibogce which has third
peduncular joint much elongated ; in the lower flagellum fifth joint of the jointed "branch" has
only 2 long spines, while the sixth joint has one, and the seventh 2 long spines. Coxse of
third pair of legs agree with those in A. Sibogce and differ from A. vil! garis in having no
tooth on the distal inner angle. Genital coxae nearly as in A. Sibogce. In the petasma the
processus ventralis (fig. 3 a) has the outer margin more sinuate than in A. vulgaris, and the
capitulum differs strongly from that in A. vulgaris, as it is nearly twice as long as processus
ventralis and a little more than three times as long as broad, with the thick part distinctly
longer than the more slender, tapering distal part; furthermore the distal part is much longer
than in A. vulgaris and towards the end very slender; the armature on the front side of the
capitulum differs considerably from what is found in the two species mentioned, the three hooks
at the proximal part of the outer margins are present, but the proximal hook is enormous and
the two other rather small, besides a good number of small hooks are arranged on the front
surface mainly in a longitudinal row from near the big hook to near the end, and the most
distal part has several irregularly arranged small or minute hooks.

An adult female, which is slightly larger than the male, agrees completely with

38

A. vulgaris in the shape of the genital area excepting that the couple of protuberances between
the basal parts of the coxse of third pair of legs are quite absent; in this feature it agrees
with A. Sibogcr, but differs from this form in having no vestige of an elevated area between
the coxse and the transverse furrow.

Remarks. — It may be seen that the two specimens described exhibit characters found
in A. vulgaris and others found in A. Sibogce, while in the spines on the lower antennular
flagellum, in the armature on the capitulum of the petasma and in the female genital area they
differ from the two species named. Having only i male and i adult female I do not venture
to establish a nevv species, though it is impossible to refer the specimens either to A. vulgaris
or to A. Sibogce; one is nearly tempted to suppose that the specimens may be bastards between
the two species. Future students who possess a good material of this dubious form and allied
species, may decide the question.

2. Acetes Sibogce n. sp. PI. III, figs. 4a — \h.

Stat. 47. March 8 — 12. Bay of Bima, near south fort. 55 m. Mud with patches of fine coral

sand. 16 specimens of both sexes.
Stat. 323. Febr. 24 — 25. Sangkapura-roads, Bawean-island. 12 m. Mud. 10 adult males, 16

adult females, and 22 immature specimens.

Male. — Eyes (fig. \a) smaller than in A. vulgaris, as the transverse diameter of the
cornea is slightly more than half as long as the distaj joint of the stalks with eye. Antennulae
with second joint conspicuously longer and thicker than in the female, third joint slender and
very elongated, not fully two and a half times as long as the inner margin of second joint.
Thickened part of upper flagellum a little shorter than the inner margin of second joint. Lower
flagellum at most a- little longer than the inner margin of second peduncular joint, with 13
joints (fig. 4<5); the shaft of the clasping organ is 3-jointed, the jointed main "branch" with only
10 joints, consequently considerably shorter than in A. vulgaris, while its proximal half is rather
curved and armed below with spines nearly as in that species; a single long, robust, moderately
curved spine originates beneath the base of fourth joint of flagellum and reaches nearly to the
spines on fifth joint of the main "branch". Antennal squama reaches to the end of second
antennular joint. Coxse of third pair of legs (fig. 4 af) without any vestige of a tooth at the
distal inner angle. Genital coxse (fig. \d) as long as broad, with the terminal corner produced
as a very short, subacute process. Exopod of uropods (fig. 4 c) nearly four and a half times
as long as broad; on the outer margin the ciliated part occupies slightly more than two-fifths
of the whole length.

The petasma (figs. 4/ — \li) is related to that in A. vulgaris, but shows some differences.
The inner margin with hooks of pars astringens is considerably shorter than in A. vulgaris,
while the differences observed in the pars externa and the proximal half of pars media are
slight. The processus ventralis [pv.) is not as long as in A. vulgaris, and its outer margin is
much more sinuate. The capitulum (c.) is rather different; it is twice as long as processus
ventralis and more than three times as long as thick ; a little more than its distal third is a
slender process tapering to the narrow, obtuse end; near the outer margin towards the processus

39

ventralis two gigantic hooks are seen on the front side (fig. \h), and at the end of the narrow
part two or three minute hooks are seen on both sides.

Length 15.7 mm.

Female. — Similar to the male excepting in the antennulse, the coxae of third pair
of legs, and the genital area. The peduncles of the antennulae as in the female A. vul garis, so
that a reference to the description is sufficiënt; lower flagellum consists of about 14 joints, and
it is almost as long as the two distal peduncular joints combined. Coxse of third pair of legs
with the inner side nearly as in the female A. vulgaris, having at the distal end a strong
tooth (fig. 4e), the inner margin concave and the produced rounded small plate at the base;
trochanter with the produced inner end sometimes close to next joint, sometimes turned a little
outwards and then seen as a free acute angle or minute tooth, but no tooth is, as in A. spi-
niger, found on the inner side just before the end.

The genital area (fig. \e) differs from that in A. vulgaris \ there is no tracé of protuber-
ances between the coxae of third legs; the deep transverse furrow is sinuate, having its sub-
lateral parts procurved and the median part recurved. Between the coxse and the furrow the
median third of the lower surface has an elevated area which has its raised lateral margins
somewhat convergent, while the posterior margin is bent a little backwards at the middle,
and each half is a little concave or frequently straight (fig. \e shows the area in its most
developed form).

Length 21.7 mm.

Remarks. — A. Sibogce is more allied to A. me/garis than to any of the following
species; its male differ from A. vulgaris especially in the long third joint of the antennulae,
in having no distal tooth on the coxae of third legs, and in the capitulum of the petasma,
while the males of the following forms differ from those of A. vulgaris and A. Sibogcz in having
the genital coxae broadly rounded anteriorly and no pars astringens on the petasma.

3. Acetes dispar n. sp. PI. III, figs. $a — 5/ and PI. IV, fig. ia.

Not gathered by the "Siboga", but the Copenhagen Museum possesses specimens from
two localities, one of which is within the "Siboga" area.

Cheribon, Java. Capt. AndrÉa 1870. 1 male, 4 females.

Lem Ngob, Gulf of Siam, in a mangrove-swamp. Dr. Th. MüRTENSEN 23/XII 1899. 2 males
and 1 immature specimen.

Male. — Transverse diameter of the eye (fig. 5 a) only about half as long as the distal
joint of the stalk with eye. In the antennular peduncles second joint is half as long as the
first; third joint is slender and very elongated, more than two and a half times as long as
the inner margin of second joint; thickened part of the upper flagellum somewhat shorter than
the inner margin of second peduncular joint. Lower flagellum a little longer than the inner
margin of second peduncular joint, with 13 joints; the shaft of the clasping organ (fig. 5 b) is
proportionately longer than in A. vu/garis, 3-jointed with first joint long; the main "branch"
has 10 joints, the proximal part is considerably curved with 2 or 3 small spines on fifth joint.

4o

i longer spine on each of the two preceding joints and i spine on the side of second joint •.
third joint of the shaft is produced in a protuberance below the insertion of the main " branch"
and on that protuberance two spines are inserted, both strongly curved, the lower robust,
extremely long, reaching the spines on fifth joint of the main "branch", the upper spine scarcely
half as long as, and much more slender than, the other. Antennal squama reaches to the end
of second joint of the antennulse. The coxse of third legs (fig. 5 d) with a tooth at the distal
inner angle, while the trochanter has no tooth near its inner end. Genital coxae (fig. 5 d) con-
siderably broader than long, anteriorly very broadly rounded. Exopod of uropods (fig. 5*") nearly
four and a half times as long as broad; the ciliated part of the outer margin is almost as long
as the glabrous part.

The petasma is most characteristic (figs. $e — 5/"). Pars astringens is completely wanting;
pars externa (e.) is somewhat large, about three times as long as broad, with the inner margin
rather concave, so that the plate is broader towards the base and considerably beyond the
middle than at the middle. Pars media has its proximal part somewhat broader than in the two
preceding species, and its basal margin is somewhat feebly concave, while the outer corner is
more produced than the inner. Processus ventralis (pv.) which originates before the middle of
pars media, has the proximal half thick, ovate, while its distal half is a slender, acute needie.
When considering the portion beyond the insertion of processus ventralis as the capitulum (c.),
its proximal major part is moderately thick, while the most distal part is broader, somewhat
widened especially inwards and forwards, oblique-ovate, with numerous hooks on the outer part
both on the posterior and the anterior surface.

Length 12.5 mm.

Female. — Eyes and antennulae nearly as in the female A. Siboga-, lower flagellum
scarcely as long as third and half of second peduncular joint combined; antennal squama does
not quite reach the middle of third antennular joint. Coxae of third pair of legs (fig. 1 d) in the
main as in the females of A. vul garis and A. Sibogcz-, trochanter without any tooth near the
distal inner end. Exopod of uropods as in the male, consequently differing from the females
of the two species mentioned in having the ciliated part of the outer margin almost or fully
as long as the glabrous part.

The genital area (fig. 1 a) is characterized by a large, subquadrangular plate somewhat
broader than long; the plate begins between the posterior part of the coxae of third legs
and reaches considerably behind the transverse furrow separating the last thoracic segment
from the penultimate; when the animal is inspected from the side, it is easily observed that
this plate protrudes freely below the ventral surface of the segments, and that a longitudinal
section through the plate would be very oblong-triangular ; seen from below the plate has its
posterior angles broadly rounded and the posterior margin otherwise rather deeply concave ;
each lateral part of the plate is elevated as a kind of keel, and the median line and the
posterior margin are. a little elevated, so that the plate has two hollowed areas.

Length of the largest specimen 15 mm.

Varietas vel sp. n. 1 — The Copenhagen Museum possesses 5 females taken pelagically
at lat. 24°i7'N., long. 11 8° 15' E. by Capt. Suenson. They agree with A. dispar in all features

4i

excepting the genital plate. In these females the plate (fig. 2#) is less broad and considerably
shorter than in the typical A. dispar, and it reaches onJy to or a little beyond the transverse
furrow; its posterior margin is somewhat concave or nearly straight, and the keels on its lower
surface are feeble. Length of a large specimen 22 mm. — Having no males I am unable to
settle whether these females are only a variety of A. dispar or belong to a separate species.

Remarks. — A. dispar is instantly separated from all forms known to me, excepting
A. chincnsis n. sp., in having the ciliated part of the outer margin of the exopod of the uropods
almost or fully as long as the glabrous part. Judging from the petasma it is allied to A. japo-
nictis Kishinoye, but as the Japanese author, who had a rich material of his form, does not
mention any sexual difference in the length of third joint of the antennular peduncles, it is
impossible to refer the typical A. dispar to his form, because the third joint mentioned is so
very much elongated in the male A. dispar, that it seems to be impossible that Kishinoye
could overlook such a sexual difference. Perhaps the females described as a possible variety
belong to the Japanese form.

4. Acetes chinensis n. sp. PI. IV, figs. 3a — 3^.

Not taken by the "Siboga", but the Copenhagen Museum possesses females from the
following localities.

Lat. 330 10' N., long. 12o,0iS'E. 40 fathoms. Capt. Suenson, 17 Sept. 1897. 5 females.
Formosa Channel, 25 fathoms. Capt. SUENSON, 23 May 1897. 1 female.

F e ma Ie. — It agrees with A. dispar in the antennulêe, the coxae and trochanteres of
third pair of legs and the exopod of the uropods (fig. $ó), but differs sharply in the shape of
the genital plate. Inside the small rounded plate projecting from the proximal inner corner of
each coxa of third legs a minute protuberance is found. Seen from the side the posterior part
of the genital plate is much thicker than in A. dispar; seen from below (fig. 3a) the plate
overreaches somewhat the furrow between the two last thoracic segqnents; from its broad base
its lateral margins converge strongly backwards and curve finally so much inwards, that the
posterior margin is their direct continuation ; the latter margin is incised at the middle; the
lower side of the plate has a broad, longitudinal excavation which especially in its posterior half
is deep, so that each lateral part of the plate looks as a thick, oblong protuberance.

Length 22 — 32 mm.

Remarks. — The genital plate differs so much from that in A. dispar that the animals
must belong- to a separate species, possibly A. japonicus Kishinoye, and it can not be difficult
to recognize the species with certainty.

5. Acetes serrulatus Kröyer. PI. IV, figs. 4a — \h.

1S59. Ser gestes serrulatus Kröyer, Kgl. D. Vid. Selsk. Skrifter, Math.-naturv. Afdeling IV, 2,
p. 268, Tab. IV, fig. 12, a — g.

The "Siboga" has not secured this species, but the Copenhagen Museum possesses it
from 3 places, 2 of which within the "Siboga" area.

SIBOGA-EXPEDITIE XXXVIII. 6

Surabaya, Java. Capt. AndrÉA 1870. 5 males, 9 females.
Cheribon, Java. Capt. ANDRÉA 1870. 1 male.
"Indo-Chinese Sea", ScHMlDT. 1 female.

Male. — Eyes (fig. 40) smaller than in A. vulgaris, their diameter being generally a
little less than half as long as the distal joint of the stalk vvith eye. Peduncles of the anten-
nulae nearly as in A. dispar; third joint from a little less to more than two and a half times
as long as the inner margin of second joint. Thickened part of upper flagellum conspicuously
shorter than the inner margin of second joint. Lower flagellum (fig. 4c) differs considerably from
those in all other species; it contains only 12 joints, as fourth and fifth joints are fused; its shaft
looks as if it consisted of only two moderately long joints, while the oblong and much more
slender third joint has the insertion of fourth joint on its upper side at the base, as the third
joint is produced considerably in advance of that insertion ; fourth joint, the first of the main
"branch", is almost vertical on the third, slender at the middle and with a triangular, very
conspicuous protuberance projecting backwards from its upper posterior angle. Second and third
joints of the main "branch" each with a long and strong spine below at the end, and a short,
robust spine on the outer side; fourth joint with 3 moderately long spines below, while the 5
remaining joints are more slender and without spines. From the protruding end of third joint
of the shaft two extremely long spines project, both nearly straight to somewhat from the end,
and the apical part is curved strongly upwards; the lower spine is somewhat longer and thicker
than the upper and reaches to the distal group of spines on the main "branch". — The
antennal squama reaches to or slightly beyond the end of second antennular joint. The coxae
of third pair of legs with a tooth from the distal inner angle (fig. 4c); the trochanter without
tooth near the end. Genital coxee (fig. \e) much broader than long, anteriorly broadly rounded.
Exopod of uropods (fig. \d) a little less than five times as long as broad; on the outer margin
the ciliated part is obviously shorter than the glabrous portion, as it occupies from scarcely
less to a little more than two-fifths of the whole length.

The petasma (fig. \g) is very curious. Pars astringens is wanting. Pars externa (ei) is
four times as long as broad, with the inner margin straight to near the end, the outer margin
subparallel with the inner to considerably beyond the middle, and then evenly curved to the
distal inner angle. Pars media is proportionately very slender excepting towards both ends; its
proximal part is at the free end produced into an inner and an outer process, both very oblong,
curved respectively strongly inwards and outwards, with their ends obtuse ; processus ventralis
wanting; the distal half of pars media, the capitulum, has its proximal portion slender, and
then it is expanded on the outer side, so that this flattened portion is somewhat more than
half as long again as broad, with about 7 hooks along the convex outer margin (fig. 4//), while
the broad end is cut off transversely and armed with a big, triangular spine.

Length 11. 5 — 16.5 mm.

Female. — Very similar to the female of A. dispar as to the eyes, the antennular,
and the coxae of third legs. The antennal squama reaches the middle of third joint of the
antennulae. Trochanter of third legs without any tooth near the end. Exopod of uropods as in
the male, consequently differing from that in the female A. dispar. The genital area (fig. 4/)

is uncommonlv simple; the furrow between the last and the penultimate thoracic segment is
quite free, deep, and curved a little forwards; there are no protuberances between the coxse
and no plate, but the transverse somewhat narrow area, marked off posteriorly by the furrow
and anteriorlv by the limit between fourth and third segment running between the posterior
part of third coxse, is very convex in the longitudinal direction.

Length of a large specimen 20.5 mm.; the type for fig. 4/ is 15.5 mm. long.

Remarks. — The male A. serndatus is easily distinguished from all other forms by
the triano-ular protuberance from the upper end of first joint in the main "branch" of the lower
antennular flagellum ; the reduced and curiously shaped petasma affords another fine character.
The female is distinguished by the genital area. — It may be noted that in the female from
the Indo-Chinese Sea the front crest on the carapace has only a single dorsal denticle, the
posterior, as the anterior denticle, which is small in normal specimens, has vanished.

6. Acetes spiniger n. sp. PI. IV, figs. 5« — 5/2.

Not captured by the "Siboga", but the Copenhagen Museum possesses specimens from
3 localities, one among them within the "Siboga" area.

Surabaya, Java. Capt. Andréa 1870. 6 females.

10 miles off Rangoon. HANSEN & THALBITZER. About 35 specimens.

uIndo-Chinese Sea". ScHMIDT. I male, 2 females.

Male. — Transverse diameter of the eyes a little less than half as long as the distal
joint of the stalk with eye. Antennulae (fig. 5 a) with second joint a little elongated and some-
what thickened; third joint very elongated, from a little more than twice to a little less than •
three times as long as the inner margin of second joint, and 'when this joint is extremely long
it is proportionately more slender than when it is only a little more than twice as long as the
margin mentioned. Thickened part of the upper flagellum considerably shorter than the inner
margin of second peduncular joint. Lower flagellum (fig. 5 c) considerably longer than second
peduncular joint, with 12 distinct joints; the shaft is long, one-third of the whole flagellum,
3-jointed, and third joint with the end a little produced, free; first joint of the main "branch"
long, in reality consisting of two joints completely or — in a single male - - somewhat incom-
pletely fused; the four proximal joints of the main "branch" taken together feebly curved,
compressed and somewhat high, highest at the middle; second and third joints each with a
moderately long spine below, and fourth joint with a row of 6 or 7 spines, the distal ones
short (in the large male from the Indo-Chinese Sea first joint has a spine below, the spines on
the three other joints are longer, and fourth joint has 8 spines). Third joint of the shaft has
above at the middle a somewhat small, spiniform, curved process looking mainly forwards, and
its end has the usual extremely long, thick spine, the submedian part of which is much curved,
and the spine reaches to the spines on fourth joint of the main "branch"; before the insertion
of the very long spine a short, straight spine originates near the end of the upper margin of
the joint. Antennal squama reaches to or slightly beyond the end of second antennular joint.
Coxae of third pair of legs (fig. 52) with a good-sized tooth at the distal inner angle; the

44

trochanter has a very conspicuous, triangular tooth on the inner side just before the end. Genital
coxae (fig. 5 e) much broader than long, anteriorly rather broadly rounded. Exopod of uropods
(fig. 5 d) slender, five times as long as broad ; on the outer margin the ciliated part occupies
more than two fifths, but conspicuously less than half of the length.

The petasma (figs. 5^ — 5^) has no pars astringens. Pars externa (e.) is about three
times as long as broad, and from a little beyond the middle the feebly convex outer margin
converges with the inner margin to the narrow but obtuse end. Pars media is moderately
slender; its proximal free part is long, with the outer margin concave to near the base, as this
most proximal part is expanded on the outer side and the basal margin is oblique, not concave.
Processus ventralis (pv.), which originates at the middle of pars media, is a very long, acute
needie reaching to somewhat from the end of the capitulum (c.) and with the base itself widened ;
the capitulum is more than three times as long as broad, narrower at the base than before
the middle, with the outer margin somewhat convex to the broad, rounded end-, numerous
nooks are arranged both on the anterior and the posterior side along the outer margin and
on the terminal portion.

Length 18 mm., a single large specimen 22 mm.

F e m a 1 e. — Eyes and antennulae in the main as in the females of the preceding forms ;
thickened part of the upper flagellum of the antennulae at least as long as second peduncular
joint; lower flagellum as long as second and third joints combined, with about 20 joints. Antennal
squama reaches about to the middle of third antennular joint. Coxse of third pair of legs (fig. 5 ƒ)
as in the female A. vulgaris, with the distal inner tooth very developed ; trochanter as in the
male with a very conspicuous, acute tooth on the inner side just before the end. Exopod of
uropods as in the male.

The genital area (fig. 5/) differs much from that in any preceding species. Inside the
posterior rounded process from each coxa is seen a rounded protuberance ; the furrow between
the penultimate and the last thoracic segments has its middle portion extremely developed, the
part of the penultimate segment situated behind each coxal protuberance is elevated as a high
and rather large, rounded protuberance directed somewhat. backwards and therefore overlapping
a small part of the furrow ; between these two pairs of protuberances the segment is deeply
excavated, and this excavation continues on the most anterior part of the last segment which
has a pair of oblong, essentially transverse protuberances narrowing the excavation from
each side.

Length generally 25 — 29 mm. ; an extremely large specimen measures 33.5 mm.

Remarks. — A. spiniger is easily separated from the five preceding species by the
tooth on the inner margin of the trochanter of third legs. In the male the clasping organ of
the antennulae and the petasma, in the female the genital area afford other excellent specific
characters. - - It may be noted that in the large male from the "Indo-Chinese Sea" the third
joint of the antennulae is less elongated (only a little more than twice as long as the inner
margin of second joint) than in the males from off Rangoon, and its clasping organ on the
antennulae is also a little more spinose, but these differences are only variation of slight
importance.

45

3^K

7.G.1)

i(-«)

II. Species from the Atlantic side of America.
7. Acetcs brasiliensis n. sp. Figs. 1 — 7 in the text.

The Copenhagen Museum possesses this species from a single place.
Brazil. COLLIN. 1 male, 1 female.

Male. — The anterior keel on the carapace has only a single tooth (fig. 1), as the
denticle, which in most forms exists between the tooth mentioned and the rostrum, has disap-
peared. The rostrum is short with the end obtuse. Eyes about as in A. spinigcr. AntenrTulae
with the peduncle long; third joint very
eloneated, a little less than two and a
half times as long as the inner margin
of second joint. (The thickened part of
the upper flagellum mutilated). Lovver
flagellum (fig. 2) has lost its distal joints
in my specimen ; its shaft is 3-jointed ;
the two proximal joints of the main
"branch" are apparently fused and have
a close row of 6 thick, obtuse spines,
and outside this row 2 spines ; the fol-
lowing joint has a strongly curved and
very robust spine twice as long as any
of the other spines, but the third joint
of the shaft has no produced free part,
and no tracé could be found of the
very long spine projecting in all other
species from that free part. The antennal squama reaches the end of second joint of the
antennulae. Coxse and trochanteres of third pair of legs without any tooth at their distal
inner angle. Genital coxa? considerably broader than long, anteriorly very broadly rounded.
Exopod of uropods (fig. 3) nearly four and a half times as long as broad ; the ciliated part
occupies scarcely two-fifths of the outer margin, and a minute tooth is seen at the end of the
glabrous part.

The petasma (figs. 4 — 6) is peculiar. Pars astringens is completely wanting. Pars externa
well developed, about two and a half times as long as broad; its distal two-fifths triangular
and slightly longer than broad. Pars media is moderately slender; its free proximal part is
long with the lateral margins subparallel, and the basal margin somewhat deeply and obliquely
concave, while the inner proximal corner is produced into a somewhat short, obtuse process,
the outer corner much broader, rounded. Beyond the insertion of pars externa pars media
narrows greatly to the thickened capitulum, and a processus ventralis could not be made out;
the capitulum is subglobular, but consists of four lobes, the inner long, sausage-shaped (fig. 5),

Figs. 1 — 7. Acctes brasiliensis n. sp.
Fig. 1. Front end of the carapace of the male.

Fig. 2. Proximal parts of upper and lower flagellum of left male antennula.
Fig. 3. Exopod of left male uropod.
Fig. 4. Left petasma, from behind.
Fig. 5. Capitulum of the same petasma, from behind.
Fig. 6. Same capitulum, from in front.
Fig. 7. Genital area and proximal parts of third legs of a female.

46

much curved and terminating in four thick and short spines ; the three other lobes are much
shorter, and each produced into an acute point.

Length 15.5 mm.

F e ma Ie. — Rostrum and crest as in the male. (The antennulae mutilated, only the
first joint present). Coxae of third pair of legs (fig. 7) with the major part of the inner margin
convex and no tooth below or at the end, while the proximal inner corner is produced into a
protuberance about as in the species from Asia. The genital area (fig. 7) is moderately short
but broad; the median part of its posterior margin, the transverse furrow, is strongly procurved,
while each sublateral part is produced backwards and very broadly rounded ; the genital area
thus limited posteriorly is, seen from below, distinctly elevated, and its median part is longi-
tudinally a little concave, but no tubercles are observed.

Remarks. — A. brasiliensis seems to be allied to A. americamis Ortmann, from the
estuary of the Amazon River. Both species agree in having only a single median tooth behind
the rostrum. Unfortunately Ortmann's figure of the copulatory organ is poor and small, and
of the clasping organ on the male antennulae he has no figure or description, so that these
organs, which always afford good characters, cannot be compared with the features in A. brasi-
liensis. But two features remain which render it impossible to refer A. brasiliensis to the species
established by Ortmann. He has examined specimens of both sexes and has not a word on
any sexual difference in the length of third joint of the antennulae, but in A. brasiliensis that
third joint is so strongly elongated in the male that he could not have overlooked this feature.
In Ortmann's fig. 27 the exopod of the uropod has the glabrous part of the outer margin some-
what more than twice as long as the ciliated part, and thus the ciliated part is proportionately
very much shorter in A. americamis Ortm. than in A. brasiliensis.

8. Acefes paragnayensis n. sp. Figs. 8 — 14 in the text.

The Copenhagen Museum possesses a large number of specimens collected by Dr. William
Sürensen in a lagoon at Rio Paraguay near its junction with Rio Parana. A single specimen
was taken by the same Zoologist in the outlet of Riacho del Oro in Rio de la Plata in feebly
brackish water.

Male. — The rostrum (fig. 9) is acuminate, acute; the median crest has posteriorly a
strong tooth, and between this tooth and the end of rostrum is a rudimentary denticle or at
least an angular bend. Eyes rather large, nearly as in A. vulgaris. Antennulae (fig. 8) with
the peduncle nearly as in A. vulgaris, as the third joint is slightly longer than in the female
and considerably less than half as long again as the inner margin of second joint; the thickened
part of the upper flagellum nearly as long as third peduncular joint. Lower flagellum (figs. 10 — 1 1)
has its shaft moderately short, 3-jointed; the main "branch" has its proximal part curved some-
what upwards, the four proximal joints fused so that only the most distal of the articulations
is partly developed, with about 4 obtuse spines at the base on the lower side, while the third
joint has a very large protuberance downwards and outwards vertically on its joint, and this
protuberance is as deep as the diameter of the joint, almost as deep as broad, somewhat

47

compressed with the angles rounded; beyond this thicker proximal portion the flagellum contains
6 slender joints; the third joint of the shaft is a little produced below, and this protuberance
has a very long, strong-, a little curved spine directed forwards and reaching a little beyond
the protuberance on the main "branch". Antennal squama reaches distinctly beyond the middle
of third joint of the antennular peduncle. Coxse of third pair of Iegs with most of the inner
margin convex and no tooth at its distal end, but on the lower side of each coxa near the
inner margin protrudes (as in the female, fig. 14) a large, oblong, acute process directed down-
wards, much forwards and a little or somewhat outwards; trochanter without any tooth at the
distal inner end. Genital coxse obliquely triangular, broader than long, with the front end sub-

4t.(,H)

nW

t^)

«e-»)

Figs. S — 14. Acetes paraguayertsis n. sp.

Fig. 8. Front part of carapace with left eye, antennula and antenna

of a male.
F'S' 9- Upper front part of carapace of the same male.
Fig. 10. Lower male flagellum, from the outer side.
Fig. II. Proximal part beyond the shaft of the same flagellurii, from

the inner side.

Fig. 12. Exopod of left uropod of a male.

Fig. 13. Left petasma, from behind ; a. pars astringens, e. pars

externa, m. pars media.
Fig. 14. Proximal parts of third legs and the genital area of a

female.

acute, and an impression on the inner side. Exopod of uropods (fig. 12) unusually broad, about
three and a half times as long as broad; the ciliated part occupies scarcely two-fifths of the
outer margin, and the glabrous part terminates in a minute tooth.

The petasma (fig. 13) is most peculiar. Pars astringens («.) is very broad, and its inner
margin with numerous coupling hooks. Pars externa (e.) is an oblong plate not quite three
times as long as broad, with the distal part broad and obliquely rounded. Pars media (m.) has
'its free proximal portion short with the basal margin oblique and somewhat concave; the distal
half is a free plate with the lateral margins subparallel, the terminal margin somewhat oblique,
a little concave at the middle, and the lateral corners are broadly rounded; this portion has
no vestige of any hooks or processes, and therefore I am not quite sure that the males are
really adult.

Length 19 mm.

Female. — Rostrum with crest and the eyes about as in the male. Antennulae with
second and third joints of the peduncle a little shorter but scarcely more slender than in the
male; thickened part of upper flagellum as long as third joint of the peduncle; lower flagellum
is somewhat longer than third peduncular joint, with about 14 joints. Antennal squama reaches
the end of the antennular peduncle. Coxa; of third pair of legs nearly as in the male (fig. 14).

48

The genital area (fig. 14) has a somewhat small, rounded tubercle behind the produced
posterior corner of each coxa; the furrow between the penultimate and the last thoracic segment
is, excepting near the sides, extremely curved with the concavity turning forwards, and the area
between this concave furrow and the tubercles mentioned is raised as two large and proportion-
ately high, a little oblong, rounded knots separated by a deep median impression.

Length 2 1 mm.

Remarks. A. paragnayensis differs from all species described in this paper in

having the exopod of the uropods considerably broader in proportion to its length, and in
possessing a process on the lower surface of the coxae of third pair of legs, while in other
forms a process or tooth, when it exists, projects from the distal inner corner of the coxae. The
shape of the exopod of the uropods excludes the possibility that this species could be identical
with A. americanus Ortm. — Most of the specimens are small and decidedly immature; some
among the females are certainly adult ; as to the males I believe that some few specimens are
adult, but as the curious petasma is without hooks, acute processes or spines on pars media,
I am not absolutely certain.

It is interesting that this species has been taken in a tributary to Rio de la Plata more
than a hundred geographical miles from the Atlantic.

II. Sub-Family Luciferix.k.
Lucifer Thomps.

With good reason the genus Lucifer J. Vaughan Thompson — or Leucifer H. Milne-
Edw. — has been separated from the other genera of Sergestidae and established as type for
a sub-family. The general morphology is on the whole well known. In* 1882 Brooks elucidated
the metamorphosis of an Atlantic species, L. Faxonii Borrad., and the material of larval stages
secured by the "Siboga" is so small that I leave this topic out of consideration. But the
"Siboga" gathered enormous quantities of subadult and adult specimens, in reality a quite unique
collection. To separate and name the species with the assistance of the existing literature was
found to be impossible, and the result is that I was forced to work out a kind of monograph.
The zoological Museum in Copenhagen possesses a good collection of this genus; the majority
of the specimens was taken at a large number of localities in the tropical and the warmer
temperate areas of the Atlantic, but besides specimens are to hand from Aden, the Bay of
Bengal, various other places in the Indian Ocean and finally from the Bay of Yeddo, Japan.
Consequently I think to possess specimens of every species inhabiting the Atlantic and the
tropical seas south of Asia, but unfortunately I have almost no material from the Pacific
excepting the areas from southern Japan to the Philippines, and it may be possible that the
vast Pacific contains a single or two hitherto unknovvn forms.

Before mentioning the literature and the specific characters it may be stated that I have
separated six species; even of the most rare of these form I have seen a good number of

49

specimens. All six species are represented in the "Siboga" collection. From the Atlantic I have
only two species, L. typus M.-Edw., and L. Faxonii Borrad.; L. typus is extremely common
in the Atlantic and scarce in the area explored by the "Siboga".

The o-enus was established in 1829 by J. Vaughan Thompson, who figured an Atlantic
specimen, but did not name the species; in 1837 H. Milne-Edwards named it L. typus, but
had not seen any specimen. According to Thompson's figure it is a species with long eye-
stalks, and as only one form with long-stalked eyes has been found in the Atlantic, where it
is extremely common, the name L. typus must be kept for this species. In 1837 Milne-Edwards
also established a species from the Indian Ocean, L. Reynaudii; his figure does not allow a
determination, and it is interesting to observe that Dana (1852) described and figured a species
with short eye-stalks, and Spence Bate (1888) a species with long eye-stalks under the name
L Reynaudii. Judging from Milne-Edwards' figure I think he examined a species with long
eye-stalks, but as two species with such eye-stalks exist in the Indian Ocean it will forever be
impossible to produce a valid interpretation, and the name L. Reynaudii ought to be dropped. -
In 1852 Dana described and figured 4 species, viz. a form with short eye-stalks determined
as L. Reynaudii and three new species. Though Kemp (19 13) says : " Dana's treatment is
fortunately very good and surpasses that of nearly all subsequent writers", I must unfortunately
maintain that it is poor. What Dana described and figured as L. Reynaudii is one of the forms
with short eye-stalks, but it is impossible to recognize it. Kemp believes that a feature seen by
Dana, viz. the presence of a pair of spinules on sixth abdominal segment of the male, is a
valid specific character, but it is no character ; these spinules are those always present in the
females and generally lost in the males, but I have found them in single specimens of L. Faxonii
and L. Hanseni Nobili. Dana's new species L. acestra is decidedly one of the two species with
long eye-stalks, it is a male, and if the figure exhibiting the telson is not very incorrect the
specimen drawn was not quite full-grown and, judging from the place of the protuberance on
the lower side of telson and especially from the shape of the posterior ventral process on sixth
abdominal segment, the specimen in question belonged to L. typus M.-Edw. Of the two other
species established by Dana as new L. pacificus is completely unrecognizable, while L. acicularis
is a quite young, not even half-grown specimen still showing two larval characters, viz. the
very short "neck" and the telson nearly as long as the uropods. — In 1905 Nobili established
and in 1906 he described more elaborately and figured a new species with short eye-stalks,
L. Hanseni, which can be recognized with certainty, as he pointed out in the text and showed
in the figures two characters, in which this species differs from all others known to me; his
animals were taken in the Bay of Djibouti (the Red Sea).

So many species had been established in 19 14. Several other authors, viz. Eydoux &
Souleyet, Claus, Dohrn, Semper, Faxon, Boas, Ortmann, Brooks and Kemp, had mentioned
or even published figures of Lucifer, referring their specimens with or without a query to L.
typus or L. Reynaudii, or distinguishing the form only as Lticifer sp. or Lucifer sp. n. ? Some
few of these publications, especially those worked out by Claus and Brooks, give important
contributions to our knowledge of the type, but for discrimination between forms they are of
slight or no significance. — In 1915 L. A. Borradaile published a treatise : "On the Species

SIBOGA-EXPED1TIE XXXVIII. 7

5Q

of Lucifer and their Distribution", in which he gave a tabular view of the forms, and besides
synonymy with notes on each species. The material examined by him seems to have been
proportionately small, and many of the characters used in the key are based 'on the figures or
descriptions in the literature. But most of these characters are either wrong or for some other
reason of slight or no value. He adopts L. Reynaudii M.-Edw. and the three species established
by Dana, even L. acicularis based on semi-larval characters; furthermore he describes a new
species, L. inermis, which is only a synonym to L. Hanseni Nobili (he had overlooked Nobili's
above-named paper, but in 1 9 1 6 in another paper he withdraws L. inermis as a synonym) ;
finally he establishes 5 new species on differences in the descriptions or figures published by
earlier authors; the result is that he has in all 11 species. As J. V. Thompson has figured a
Lucifer, and Dana's L. acestra is without any rostrum, he considers this feature as a real
specific character, though it is only an error, as a rostral process is always well developed in
my immense material. The shape of the terminal part of the exopod of the uropods differs
according to sex, and besides it exhibits some individual variation, so that this part cannot be
used as a character in the way applied by Borradaile in his key. Errors in earlier figures
as to length of the thoracic legs are also used as characters. Among his five new species
based on the literature only one can be accepted, viz. L. Faxonii Borrad., because it can be
recognized, as it is the only species with short eye-stalks inhabiting the Atlantic, at least north
of the line.

Of the 1 2 species established in the whole literature only 3 can be adopted, viz. L.
typus M.-Edw., L. Faxonii Borrad., and L. Hanseni Nobili. L. tyfus has long and L. Faxonii
short eye-stalks, and both were founded on specimens taken in the Atlantic north of the line,
where no other form of the genus lives ; L. Hanseni (L. inermis Borr.) can be recognized by
Nobili's figure. All the remaining names in the literature must be cancelled forever either as
synonyms or as quite unrecognisable. As already mentioned I have in all 6 species, 3 of which
I must name.

Every adult male can be determined with absolute certainty, as the structure of the
petasma affords excellent specific characters. Adult females of two species can always be
determined with certainty, but I have not been able to find any really sharp character between
females of the two species with long eye-stalks or between the females of two of the four
species with short eye-stalks, viz. L. penicillifer n. sp. and L. intermedius n. sp. ; yet it may
be added that the majority of the females of the two last-named species can be separated,
but some females of the two species are closely similar. More than half-grown but immature
specimens can generally be determined, when adult females of the same forms can be separated.
The "Siboga" frequently captured specimens of three or four species in the same haul. The
analytical keys and the description of the species may elucidate sufficiently the specific
characters, differences according to sex and individual variation ; only the male petasma must
be described here.

The petasma is fixed on the inner side of the peduncle of the pleopod (Pis. IV and V,
several figures) ; it projects forwards and obliquely downwards as a somewhat thick plate, and
its distal part is obliquely folded strongly inwards and besides directed a little downwards. The

5i

basal portion of this incurvate part is broad, while its terminal portion is moderately or very
narrow (f. inst. PI. V, figs. ie, 2g, $g, 4/), and it lies obliquely or nearly transversely on the
inner side of the pleopod, in the main or wholly beyond the fixed part of the petasma. The
result is that when the animal lies on the right side, thus turning the left side upwards, it
is impossible to see half or more than half of the petasma of left pleopod, as both its
broad proximal part and its terminal more or less narrow portion is covered by the peduncle
of the pleopod. As the shape of the narrow portion of the petasma is of the highest import'ance
for determining the species, and this ought to be possible without damaging the specimen by
cutting off one of the pleopods of first pair, I may advise the student to place the male in
some drops of water on an object glass so, that its right side is turned upwards, and then
with a needie to discard the first right pleopod backwards or forwards, so that the inner side
of left petasma and especially its narrow part is freely seen from above, and then to look
on its shape under a magnifying power of 140 or 150 times. When one has acquired some
experience, an examination of this simple kind will be sufficiënt for determining instantly every
adult male in comparing the shape of the narrow portion of the petasma with my figures. But
when an investigation of the whole structure of this narrow portion shall be undertaken it is
necessary to remove the pleopod, partly unfold the petasma so that its narrow portion is directed
considerably forward or nearly parallel with the pleopod (PI. IV, figs. 6g and je; PI. V, fig. \ni),
and undertake a partial dissection of the narrow portion under a simple microscope magnifying
about ióo times.

In comparing the petasma with those in Sergestes or Sicyonella great differences are seen.
Of the three main-parts observed in these genera two, viz. pars externa and pars astringens,
are completely wanting in Lucifer, while pars media, which in Sergestes, Sicyonella and Acetes
is fixed by a somewhat short, proportionately narrow stalk, has in Lucifer no such stalk, but
an extremely broad basal pars lying flatly on the inner side of the pleopod. The narrow
terminal portion answers to the distal third or two-fifths of pars media in Sergestes. In all species
of Lucifer the narrow portion constitutes a kind of sheath open on the side and enclosing a
well chitinized element {pv. in many figures on Pis. IV and V) which I think is homologous
with processus ventralis in Sergestes and most species of Acetes. In two species, L. Faxonii and
L. Hanseni, this process is shaped as a long, acute needie (PI. V, figs. 3/2 — 32', figs. \n — 4.0);
in L. penicillifer it is broader (PI. V, figs ii — -2k), distally shaped as an oblong, concave lamella
with its bifid end adorned with numerous short chitinous threads, so that a bipartite brush is
formed. In L. interniedius processus ventralis is a narrow, robust plate (PI. V, figs. if — ig, pv.)
distinctly widened near the end which is deeply cleft. In L. typus and L. orientalis the same
process is a somewhat broad plate (PI. IV, figs. 6/2 and 6k, figs. 7/ — jg, pv.) with its distal
half widened and cleft by a long and deep incision differently shaped in the two species. The
sheath is rather simple in L. Faxonii and L. Hanseni, where it is oblong conical, somewhat
curved (PI. V, figs. i,g — 3/2, figs. \m — \n) with the end more or less acute, and its side opposite
the base is well chitinized (ch.), while the proximal side is so membranous that it is easily
overlooked. In L. penicillifer the membranous part (PI. V, figs. 2g — 2/2, ?u.) of the sheath
shows an angle and is not easily perceived ; the distal part of the sheath is well chitinized

52

(PI. V, figs. 2g — -2?', c/i.) and much of it scabrous from numerous small, sharp knots; besides
it is slender with die end distinctly expanded and oblique. In L. intertnedius the well chitinized
part of the sheath has its end broadly rounded, and somewhat before the end on the side
opposite the base of the petasma two plate-shaped, rather conspicuous protuberances (/. in
PI. V, figs. \e, \f, ig), and on the distal part of inner surface a number of nearly regular,
transverse, very fine but conspicuous lines {s. in fig. if). In L. typus and L. orientalis the
terminal part of the petasma is considerably thicker than in the four other species; in L. typus
(PI. IV, figs. 6g — 6//) its rather broad end is obtuse with a nearly rudimentary, triangular
protuberance ; in L. orientalis (PI. IV, figs. je — jf) the end is broad and divided into three
.triangular lobes; in both species nearly more than the distal third of the inner surface is adorned
with transverse, conspicuous lines (s.). In L. typus the sheath encloses not only the above-named
plate-shaped processus ventralis, but besides a long, well chitinized, stick-shaped process (PI. IV,
figs. 6k and 6k, k.), which has its distal part strongly bent so that the process is a hook with
a long shaft and the end very acute; I am unable to interpret the morphological equivalence
of this hook which does not exist in the five other species. The figures and the explanation of the
plates will add various particulars and help to the understanding of the brief description given.

In all species a protuberance is observed on the front margin of the first male pleopod
slightly beyond the petasma. The shape of this protuberance (p. in PI. IV, figs. 6g and je,
PI. V, figs. ie, 2g, $g> 4^> 4m) ar>d its equipment with prickles on the end is not without
specific value.

The 6 species may be divided into two groups, separated by some characters.

A. Distance between the labrum and the insertion of the eye-stalks somewhat or only a little
longer than the eye-stalks with eyes (the basal short joint of the stalks included). Posterior
ventral process on sixth abdominal segment in the male with its distal part swollen. Terminal
portion of the petasma moderately thick, and the processus ventralis shaped as a somewhat
broad plate without any terminal brush.

B. Distance between the labrum and the insertion of the eye-stalks almost twice or more than
twice as long as the eye-stalks with eyes. Posterior ventral process on sixth abdominal
segment tapers to the narrow, obtuse end. Terminal portion of the petasma rather or very
slender, and the processus ventralis never shaped as a somewhat broad plate without brush,
but either slender or terminating in a bipartite brush.

Group A.

The animals of this section differ in aspect very considerably from those of group B by
the long eye-stalks. These stalks have besides their major part very slender; the eyes are
conspicuously larger than in group B, and larger in the males than in the females. The exopod
of the uropods is very narrow, in the males from more than five to six times as long as broad,
in the females from five to somewhat more than five times as long as broad.

The group comprises only 2 species. While I have been unable to find any sufficiently
sharp difference between the females of these species, their males are extremely easy to separate
by the following key.

53

a. On the telson the posterior margin of the large ventral protuberance
is somewhat remote from the end of the telson, and the same is
the case with the distal pair of dorsal spines. The petasma has the
end rather broad and obtuse, at most with a rudimentary protuber-
ance ; the plate-shaped processus ventralis has the bottom of its deep
terminal incision transverse, and the sheath encloses besides a long-
stalked hook L. typus H. M.-Edw.

i. On the telson the posterior margin of the' big ventral protuberance
is near the end of the telson, and the same is the case with the
distal pair of dorsal spines. The petasma is at its end proportionately
broad and produced into three triangular lobes; the plate-shaped
processus ventralis has the terminal incision extremely deep and
tapering to the acute end, and the sheath encloses no hook. . . L. orientalis n. sp.

i. Lucifer typus H. M.-Edw. PI. IV, figs. 6a — 6k.

1829. Lucifer J. Vaughan Thompson, Zool. Researches, IV, p. 58, PI. VII, fig. 2.

1837. Leucifer typus H. Milne-Edwards, Hist. Nat. Crust. T. II, p. 469.

1852. Lucifer acestra Dana, U. S. Expl. Exped. Crust. I, p. 671, PI. XLIV, figs. 9, a — i.

[At least partim].
1871. ? Lucifer Reynaudi Dohrn, Zeitschr. wiss. Zool. Bd. XXI, p. 357, Taf. XXVII, Fig. 1 — 10.
[882. Lucifer Reynaudii Bate, Challenger Rep., Zool., Vol. XXIV, p. 466, PI. LXXXTV.

[At least partim].

Borradaile, in Ann. Mag. Nat. Hist. ser. 8, Vol. XVI, p. 227 — 230 (191 5), has the
following four names: L. typtis H. M.-Edw., L. acestra Dana, L. Clansi Borrad. and L. Batei
Borrad., all referring to figures of L. typus, while two of the authors quoted have in all
probability, judging from their lists of localities, mixed up specimens of L typus and L. orientalis.

Stat. 128. July 22. Lat. 40 27' N.. long. I25°25'.7 E. 1645 m. Hensen vertical net, from 700 m.

to surface. 16 specimens (cf and Q).
Stat. 129. July 22 — 23. Anchorage off Kawio- and Kamboling-islands, Karkaralong-group.

23 — 31 m. 5 specimens ((ƒ and 9)-
Stat. 133. July 25. Anchorage off Lirung, Salibabu-island. Depth up to 36 m. 2 males (and

females together with both sexes of L. orientalis).
Stat. 194. Sept. 15. Lat. i°53'.5S., long. i26°39'E. 1504 m. Townet. 5 specimens ((ƒ and Q)-

Description. — The distance between labrum and the insertion of the eye-stalks is
abput one-seventh as long again as eye-stalks with eyes: the major part of these stalks is very
slender, and the large eyes conspicuously larger in the males than in the females. The anterior
ventral process on sixth abdominal segment in the male (fig. 6 a) is almost as long as the
posterior, slender, while the swollen distal part of the posterior process is bent considerably
upwards. In the male telson (fig. 6e and 6/) the ventral protuberance is directed downwards
and slightly or conspicuously forwards ; the lower margin behind the protuberance is more than
half as long as the protuberance itself, and the posterior pair of dorsal spines on the telson
are placed above or slightly beyond the posterior margin of the protuberance, so that these
spines are rather removed from the conspicuous outer pair of terminal spines. — The exopod

54

of the uropods differs as usual in the two sexes. In the male (figs. 6 a— 6 c) it is from a little
more than five to more than five and a half times as long as broad, and the apical marginal
process vs moderately long or very long, but the terminal part of the uropod shows yet con-
siderable individual variation, as sometimes the end of the uropod has its margin somewhat
flatly curved, which is the case when the marginal process exhibits itself nearly as a continuation
of the uropod, while sometimes the end of the uropod has the margin deeply curved, and in
this case the process originates a little before the terminal upper angle of the uropod; forms
intermediate between the two shapes described are common. In the female the exopod is five
times as long as broad; its end (fig. 6d) is oblique so that the marginal spine, which is smaller
than in the males, originates slightly or somewhat before the upper terminal angle of the uropod,
and reaches to or a little beyond that angle.

The petasma is shown in fig. 6g from the inner side and partly unfolded, so that its
terminal portion is removed from the pleopod. This terminal portion is seen to be proportionately
robust as compared with its shape in the forms figured on PI. V; in fig. 6// it is shown with
transmitted light, and the shading is made according to the degree of chitinization. The end is
broad, flatly and obliquely rounded with a rudimentary protuberance ; the long hook {Ji) is very
conspicuous, and the lamelliform processus ventralis (pv.) rather distinct. Fig. 6i exhibits the
same portion, but the proc. ventralis has been removed. The transverse, undulating, fine, dark
lines are distinct on both figures. Fig. 6 k exhibits the terminal portion of a third specimen ;
the lamelliform proc. ventralis is turned out of the sheath ; a special description of this process
is scarcely needed, and only one thing may be emphasized, viz. that the bottom of the deep
terminal incision is transverse. The process at the front margin of the pleopod beyond the
insertion of the petasma is seen (fig. 6g) to be slender, much longer than thick, with two or
three sometimes nearly indistinct prickles on the rounded end.

Length of a large male (from the tropical Atlantic) 12.4 mm., of a large female 12 mm.

Distribution. — ■ L. lypus is evidently far from common in the "Siboga" area, as it
was taken only at four places, and three among these are even rather near each other. The
Copenhagen Museum possesses it from Manilla ("Galathea"); from lat. ió°8'S., long. iii°5o'E.
(Capt. Andréa), and from the Bay of Bengal ("Galathea"); furthermore from more than thirty
localities in the Atlantic, and from Messina. Of the Atlantic places more than twenty five are
north of the line, the most northern at lat. 340 io' N., long. 42°io/ W. ; the two most southern
localities are respectively lat. 28°43/S., long. 25°i4/W.. and lat. 40°32/S., long. 52°2'W.
As our Museum possesses such a rich material from so many places in the Atlantic, and I
did not find a single male specimen of the other species with long eye-stalks among the
material from this Ocean, I think that all specimens referred to L. reynaiidi M.-Edw. (Z. acestra
Dana) by Ortmann (1893) and taken by the German Plankton-Expedition belong to L. typus.
Ortmann says that it is "eine echte Plankton-Form, die sich nur in den warmeren Meeren
findet, dort aber so allgemein verbreitet ist, dass sie fast in allen Fangen erhalten wurde"; he
enumerates an enormous number of stations where it has been gathered, and hts Taf. X, a.
track-chart of the expedition, shows its quantitative occurrence ; the most northern of the stations
is in the Florida current far south of New Foundland about at lat. 42° N.

55

As no author has separated the two species of this group from one another, and as
L. orietitalis is much more common in the Indian Ocean than L. typus, all localities found in
the literature on the occurrence of a species with long eye-stalks in that Ocean or in the
Pacific must be discarded as without value.

2. Lucifer orientalis n. sp. PI. IV, figs. ja — jg.

Stat. 37. March 30 — 31. Sailus Ketjil, Paternoster-islands. 27 m. and less. 24 specimens.
Stat. 66. May 7 — 8. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer.

8 — 10 m. Plankton. 12 specimens.
Stat. 81. June 14. Pulu Sebangkatan, Borneo-bank. 34 m. Plankton. 2 specimens.
Stat. 104. July 2 — 3. Sulu-harbour, Sulu-island. 14 m. Townet. 1 specimen.
Stat. 106. July 4. Anchorage off Kapul-island, Sulu-archipelago. 13 m. Townet. 4 specimens.
Stat. 133. July 25. Anchorage off Lirung, Salibabu-island. Depth up to 36 m. 2 males (and

females together with L. typus).
Stat. 136. July 29 — Aug. 3. Ternate anchorage. 23 m. Townet, surface. 60 specimens.
Stat. 138. August 3. Anchorage on the east coast of Kajoa-island. 66 m. Townet, surface.

8 specimens.
Stat. 140. Aug. 4 — 5. Bay of Batjan. 13 m. Townet. 3 specimens (cf, 9)-
Stat. 141. August 5. Lat. i°o'.4S., long. I27°25'.3E. 1950 m. HENSEN vertical net, from

1500 m. depth to surface. 10 specimens.
Stat. 143. Aug. 7. Lat. i°4'.5 S., long. I27°52'.6E. 1454 m. Hensen vertical net, from 1000 m.

to surface. 1 male.
Stat. 148. Aug. 10. Lat. o°i7'.6S., long. 1290 14'. 5 E. 1855 m. Hensen vertical net, from

1000 m. depth to surface. 1 female.
Stat. 157. Aug. 15 — 16. Lat. o^'.gS., long. I30°I4'.6E. 45 m. Townet. 1 male, 1 female.
Stat. 177a. Sept. 1. Lat. 2°3o'S., long. I29°28'E. Townet. 2 females.
Stat. 189a. Sept. 12. Lat. 2°22'S., long. 126° 46' E. Townet. 7 specimens.
Stat. 194-197. Sept. 15. Lat. i°53'.5-i°45'.3 S., long. 1260 39-i27°8'.3 E. Plankton. 2 males.
Stat. 203. Sept. 19. Lat. 30 32'.5 S., long. I24°I5'.5E. Hensen vertical net, from 1500 m.

depth to surface. Numerous specimens.
Stat. 220. Nov. 1 — 3. Anchorage off Pasir Pandjang, west coast of Binongka. 278 m. Townet,

surface. 20 specimens.
Stat. 225. Nov. S. 5700 m. N. 2790 E. from Southpoint of South-Lucipara-island. 894 m.

Horizontal cylinder. 9 specimens.
Stat. 243. Dec. 2. Lat. 4°3o'.2S., long. I29°25'E. Hensen vertical net, from a depth of

1000 m. to surface. 1 female.
Stat. 245. Dec. 3. Lat. 4° 16.5 S., long. i30°i5'.8E. Townet, surface. 4 specimens.
Stat. 276. Jan. 9. Lat. 6°47.5 S., long. i28°4o'.5 E. Hensen vertical net, from 750 m. to

surface. 7 specimens.
Near Stat. 300. Between Timor and Lomblen. Plankton. 4 specimens (cf, Q).

Description. — Very similar in aspect to L. typus. The eye-stalks are still slightly
longer, as the distance between their insertion and the labrum is only about one-tenth as long
again as eye-stalks with eyes. The ventral processes on sixth abdominal segment in the male
(fig. 70) about as in L. typus, excepting that the swollen distal half of the posterior process is
bent feebly upwards, conspicuously less than in L. typus. The male telson (fig. J d) has the ventral
protuberance more semiglobular with the middle part of its lower margin more convex than in
L. typus, furthermore the lower margin of the telson behind the protuberance is very short,
twice or three times shorter than in L. typus, and the posterior pair of dorsal spines are situated

56

only a little in advance of the outer terminal spines. The exopod of the uropods is in the
male (fig. "ja) a little more narrow than in L. typus, about six times as long as broad, and
the marginal process is frequently still more produced (fig. jö) than in L. typus. In the female
the exopod is a little or somewhat more than five times as long as broad; its end is sometimes
shaped as in L. typus, sometimes the terminal margin is considerably oblique (fig. je), and
then the marginal spine reaches almost or fully as far backwards as the upper distal angle.

The petasma (fig. j é) has the terminal portion thicker than in L. typus, and it terminates
in three triangular lobes. Fig. 7/, drawn with transmitted light, exhibits these lobes, the fine
transverse Unes (s.) on the two largest lobes, furthermore the enclosed processus ventralis (pv.).
In fig. jg the sheath is seen from another side, open, and the processus ventralis is turned
totally out and bent backward; this rather broad, lamellar process differs considerably from
that in L. typus in having the terminal incision much deeper and narrowing to its acute end ;
the long hook-shaped process found in L. typus is entirely wanting. The process at the front
margin of the pleopod beyond the insertion of the petasma is nearly as in L. typus, but with
some more prickles on its end.

Length of good-sjzed specimens of both sexes 1 [.5 mm.

D istri buti on. — The list of the localities shows that L. orientalis has been taken
at more than twenty stations; it is thus much more common in the "Siboga" area than L. typus,
but in most cases the number of specimens is small. The Copenhagen Museum possesses L.
orientalis from two places, viz. Manilla ("Galathea") and Aden (Mr. H. Mortensen) ; the last-
named locality, at the entrance to the Red Sea, is of interest.

Group B.

The animals belonging to this section differ in aspect very considerably from those of
group A by the proportionately short eye-stalks (PI. IV, fig. 8; PI. V, figs. 2a, 30, 40). These
are sometimes rather slender to somewhat from the eyes, but most frequently they are moder-
ately or decidedly inverted conical; the eyes are smaller in proportion to the animal than in
group A, and only slightly or not at a!l larger in the males than in the females. The exopod
of the uropods differs in breadth according to species and sex, from slightly more than five to
only four times as long as broad.

The group comprises 4 species. The females of two of the species, L. Faxonii and L.
Hanseni, can be separated from one another and from the two other species, L. intermcdius
and L. penicillifcr, but it is sometimes impossible to separate with certainty females of the
two last-named species. — The following keys may be useful for students of the genus.

Key to the Males.

a. Terminal portion of the petasma has the end broadly rounded, a
number of fine transverse lines on the inner side of its distal part,
and two freely protruding, very conspicuous, small plates at the front
margin. Proc. ventralis is a narrow plate with its broader terminal

57

part deeply incised, but with any brush. (First antennular joint at
most reaching the front margin of the eyes and generally distinctly

shorter) L. intermedius n. sp.

l>. Terminal portion of the petasma has the end distinctly expanded as
a kind of oblique plate, the distal part has no transverse lines and
no protruding plates, but its convex proximal side is scabrous from
small, transverse, sharp knots. Proc. ventralis is a moderately slender
plate terminating in a more or less distinctly bipartite brush. (First
antennular joint reaches at most slightly beyond the front margin
of the eyes, and is generally a little shorter, not reaching to that

maro-in) '. . . . L. penicillifer n. sp.

c. Terminal portion of the petasma with the end acute, and no trans-
verse lines or protruding plates or scabrousness. Proc. ventralis is a
slender needie with acute end.

a. Exopod of uropods with the marginal process reaching beyond
the upper terminal angle. (First antennular joint overreaches

conspicuously the eyes) L. Faxonii Borrad.

8. Exopod of uropods with the dentiform marginal process termi-
nating conspicuously and generally far before the upper terminal
angle. (First antennular joint about as long as or a little longer
than the eyes) L. Hanseni Nobili.

K e y t o the Females.

a. Exopod of uropods from somewhat more than four to a little less
than five times as long as broad; the marginal spine terminates only
somewhat or a little before the distal upper angle or even beyond
that angle.

a. First antennular joint reaches at most a little and most frequently

not beyond the eyes L. intermedius n. sp., and L. penicillifer n. sp.

8. First antennular joint reaches considerably beyond the eyes . L. Faxonii Borrad.

b. Exopod of uropods somewhat broad, only about four times as long
as broad; its marginal tooth terminates very considerably before the

distal upper angle * L. Hanseni Nobili.

3. Lucifer intermedius n. sp. PI. IV, figs. Sa — &ó; PI. V, figs. ia — \g.

Stat. 7. March. 11. Lat. 7°55'.sS., long. ii4°26'E. 15 m. and more. 5 specimens.

Stat. 35. March 28. Lat. 8°o'.3 S., long. ii6°5o/E. 1310 m. Surface. 15 specimens.

Stat. t,j. March 30—31. Sailus ketjil, Paternoster-islands. 27 m. and less. Surface. Numerous

specimens.
Stat. 66. May y—8. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer.

8 — 10 m. Large number of specimens.

SIBOGA-EXFEDIT1E XXXVIII. °

58

Stat. 75. June S. Lat. 4°57'.4S., long. ii9°2'.3E. 18 m. Hensen vertical net, from 11 m.

to surface ; electric light in net. 4 specimens.
Stat. Si. June 14. Pulu Sebangkatan, Borneo-bank. 34 m. Plankton. 4 specimens.
Stat. 106. July 4. Anchorage off Kapul-island, Sulu-archipelago. 13 m. Plankton. 1 specimen.
Stat. 109. July 5 — 6. Anchorage off Pulu Tongkil, Sulu-archipelago. 13 m. Plankton. 3 specimens.
Stat. 117^. July 12. Lat. i°i5'N., long. I23°37'E. Townet. Many specimens.
(?Stat. 132). July 25. About Lat. 5°56'.7N., long. i26°2s'E. Townet. Many specimens.
Stat. 136. July 29 — Aug. 3. Ternate anchorage. 23 m. Plankton. 12 specimens.
Stat. 138. Aug. 13. Anchorage on the east coast of Kajoa-island. 66 m. Plankton, iospecimens.
Stat. 141. Aug. 5. Lat. i°o'.4S., long. I27°25'.3E. Hensen vertical net, from 1500 m. depth

to surface. 3 specimens.
Stat. 144. Aug. 7 — 9. Anchorage North of Salomakiëe-(Damar-)island. 45 m. Plankton. 3

specimens.
Stat. 157. Aug. 15 — 16. Lat. o°32'.9S., long. I30°I4'.6E. Townet. 4 specimens.
Stat. I77a. Sept. 1. Lat. 2°3o'S., long. I29°28'E. Townet. 13 specimens.
Stat. 189*. Sept. 12. Lat. 2°22'S., long. I26°46'E. Townet. 11 specimens.

Description. — The distance between the labrum and the insertion of the eye-
stalks about, or slightly more than, tvvice as long as the stalks with eyes; the stalks are not
conical but subcylindrical to somewhat before the eyes (fig. Sa). First antennular joint at most
reaching the anterior margin of the eyes, generally distinctly shorter. On sixth abdominal seg-
ment (fig. 1 a) the fitst ventral process is as long as, or generally somewhat or much shorter
than, the second, very acute, a little curved and placed about mid-way between the base of
the segment and second process; the latter tapers to the rather narrow, obtuse end. Telson in
the male (fig. Só) differs considerably from those in group A in having the ventral protuberance
much smaller; this protuberance is directed downwards and only a little or slightly backwards.
Exopod of uropods in the male (fig. ia) five or a little more than five times as long as broad;
the short terminal margin is transverse or a little oblique (figs. 1 b and 1 c), because the marginal
process, which varies much in length, originates a little in front of or below the upper distal
angle of the exopod, and the process overreaches somewhat or very much the transverse hind
margin. In the female the exopod is a little broader, not fully five times as long as broad;
the terminal margin is rather oblique (fig. 1 d), and the marginal process terminates below or
a little before the upper distal angle of the exopod.

The petasma^ (figs. ie — ig) has the terminal portion rather narrow and very peculiar.
The end is broadly rounded without any protuberance, but on the distal lateral margin two
protuberances are very conspicuous, the proximal much broader than the distal, and at a closer
investigation, especially when the organ is examined from in front (fig. 1 g), each protuberance
{/.) is seen to be a freely protruding, obliquely inserted plate with its free margin almost semi-
circular; the distal part of the inner side of the terminal portion is adorned with a good number
of fine but very distinct transverse lines (fig. 1 e, and especially fig. 1 ƒ, s.) about as in the
species of group A. The processus ventralis (pv.) is a very long, narrow plate with its distal
part somewhat widened, and its end is deeply and broadly incised with the bottom of the
incision rounded, and without any brush. The process (/>.) on the front margin of the pleopod
beyond the petasma is slender with a few prickles on the end.

Length of a male 10.3 mm., of a female 11 mm.

59

Remarks. — The name L. intermedius is given to this species, as it, though belonging
in general aspect and most characters to group B, has in the petasma the distally deeply incised
processus ventralis, and especially the transverse lines on the distal inner side of its terminal
portion. Besides, the eye-stalks are not conical as f. inst. in L. Faxonii, and the exopod of the
uropods is somewhat narrow. The male resembles that of L. Faxonii and differs from the two
other species of this group in having on the exopod of the uropods the marginal process or
tooth conspicuously or much overreaching the upper distal angle of the exopod; the female
can frequently, but sometimes not, be distinguished with absolute certainty from every female
of L. penicillifer.

Dist r ibu tio n. — According to the list oflocalities this species is rather common in
the major part of the "Siboga" area. The Copenhagen Museum possesses it from lat. o°i4'N.,
long. io7°6/E. (Capt. Andréa); Chinese Sea, Hongkong — Shanghai ("Galathea"), and a good
number from the Gulf of Yeddo, Japan ("Galathea").

4. Lttcifcr penicillifer n. sp. PI. V, figs. 2a — 2k.

Stat. 7. March 11. Lat. 7°S5óS., long. ii4°26 E. 25 m. and more. 11 specimens.

Stat. 16. March 15 — 16. Bay of Kankamaraan, S. coast of Kangeang. 22 m. Electric light

in vertical net. 15 specimens.
Stat. 35. March 28. Lat. 8° 0.3 S., long. ii6°5o,'E. Surface. Numerous specimens.
Stat. ij. March 30 — 31. Sailus ketjil, Paternoster-islands. 27 m. and less. Large number of

specimens.
Stat. 40. April 2. Anchorage off Pulu Kawassang, Paternoster-islands. 12 m. Townet. 2

specimens.
Stat. 66. May 7 — 8. Bank between Bahuluvvang and Tambolungan, South of Saleyer. 8 — 10 m.

Plankton. Large number of specimens.
Stat. 81. June 14. Pulu Sebangkatan, Borneo-bank. 34 m. Plankton. 8 specimens.
Stat. 93. June 24 — 25. Pulu Sanguisiapo, Tawi-Tawi-islands, Sulu-archipelago. 12 m. Plankton.

(night). i specimen.
Stat. 96. June 27. South-east side of Pearl-bank, Sulu-archipelago. Townet. About 30 spe-
cimens.
Stat. 98 — 99. June 28 — 30. Lat. 6° 9' — 6°7'.5 N., long. i2o°2i' — I20°26'E. Townet. Numerous

specimens.
Stat. 99. June 28 — 30. Lat. 6° 7'. 5 N., long. I20°26' E. 16 — 23 m. Surface. Numerous specimens.
Stat. 105. July 4. Lat. 6° 8' N., long. i2i°i9'E. 275 m. Plankton. Many specimens.
Stat. 106. July 4. Anchorage off Kapul-island, Sulu-archipelago. 13 m. Townet. Large number

of specimens.
Stat. 107. July 5. Lat. 6° i'.5 N., long. i2i°28'E. 1 specimen.
Stat. 109. July 5 — 6. Anchorage off Pulu Tongkil, Sulu-archipelago. 13 m. Townet. Many

specimens.
Stat. 112. July 7. Lat. 30 1' N., long. 122° 2' E. Horizontal cylinder. 2 specimens.
Stat. 117a. July 12. Lat. I°I5'N., long. I23°37'E. Townet. Numerous specimens.
Stat. 125. July 18 — 19. Anchorage off Sawan, Siau-island. 27 m. 4 specimens.
Stat. 128. July 22. Lat. 4°27'N., long. I25°25'.7E. Hensen vertical net, from 700 m. to

surface. 3 specimens.
Stat. 136. July 29 — Aug. 3. Ternate anchorage. 23 m. Townet. Many specimens.
Stat. 138. Aug. 3. Anchorage on the east coast of Kajoa-island. 66 m. Townet. Large number

of specimens.
Stat. 140. Aug. 4 — 5. Bay of Batjan. 13 m. Townet. About 25 specimens.

6o

Stat. 141. Aug. 5. Lat. i°o'.4 S., long. I27°25'.3E. 1950 m. HENSEN vertical net, from 1500 m.

to surface. Many specimens.
Stat. 143. Aug. 7. Lat. i°4'.S S., long. I27°52'.6E. 1454 m. Hensen vertical net, from 1000 m.

depth to surface. 6 specimens.
Stat. 144. August 7 — -9. Anchorage north of Salomakiëe-(Damar-)island. 45 m. Townet. Large

number of specimens.
Stat. 146. Aug. 9. Lat. o° 36' S., long. I28°32'.7E. 512 m. Townet. 3 specimens.
Stat. 157. Aug. 15 — 16. Lat. o°32'.9S., long. I30°I4'.6E. 45 m. Townet. 4 specimens.
Stat. 165. Aug. 20 — 22. Anchorage on North-east side of Daram-island, East coast of Misool.

49 m. Townet. Numerous specimens.
Stat. 168. Aug. 22 — 23. Anchorage North of Sabuda-island. 63 m. Townet. Many specimens.
Stat. 174. Aug. 28 — 29. Waru-bay, North coast of Ceram. 18 m. Townet. 8 specimens.
Stat. 177a. Sept. 1. Lat. 2° 30' S., long. I29°28'E. Townet. Large number of specimens.
Stat. 1S4. Sept. 11 — 12. Anchorage off Kampong Kelang, South coast of Manipa-island. 36 m.

Townet. Many specimens.
Stat. 185. Sept. 12. Lat. 3°2o'S., long. i27°22'.9E. Hensen vertical net, from 1536 m. to

surface. 23 specimens.
Stat. 189a. Sept. 12. Lat. 2°22'S., long. I2Ó°46'E. Townet. Many specimens.
Stat. 194. Sept. 15. Lat. i°53'.5S., long. I2Ó°39'E. Townet. Many specimens.
Stat. 194 — 197. Sept. 15. Lat. i°53'.S — 1°45'-3 S., long. I2Ó°39' — I27°8'.3E. Plankton. 4

specimens.
Stat. 203. Sept. 19. Lat. 30 32'.5 S., long. I24°i5'.s E. Hensen vertical net, from 1500 m. to

surface. 9 specimens.
Stat. 206. Sept. 21. Buton-strait. Surface. 4 specimens.
Stat. 220. Nov. 1 — 3. Anchorage off Pasir Pandjang, West coast of Binongka. 278 m. Townet.

6 specimens.
Stat. 225. Nov. 8. 5700 m. N. 2790 E. from Southpoint of South-Lucipara-island. 894 m.

Horizontal cylinder. Many specimens.
Stat. 243. Dec. 2. Lat. 4°3o'.2S., long. I29°25'E. Hensen vertical net, from 1000 m. to

surface. 1 specimen.
Stat. 245. Dec. 3. Lat. 4° 16'. 5 S., long. I30°I5'.8E. Townet. Many specimens.
Near Stat. 300. Between Timor and Lomblen. Plankton. 4 specimens.
Stat. 315. Febr. 17 — 18. Anchorage East of Sailus Besar, Paternoster-islands. Surface. 6

specimens.

Description. — The distance between labrum and the insertion of the eyes is more
than twice as long as eye-stalks with eyes; the stalks either shaped as in L. intermedius or some-
what conical (fig. 2 a). First antennular joint reaches at most slightly beyond the eyes, but generally
it is a little shorter, not reaching the front margin of the eyes. Sixth abdominal segment in
the male (fig. 2 ö) nearly as in the preceding species. Exopod of uropods in the male (fig. 2 ö)
a little less slender than in L. intermedius, about four and a half times as long as broad;
its terminal margin (figs. 2 c and 2 d) is somewhat or considerably oblique, and the marginal
process is a moderately long or short triangular tooth not reaching beyond the upper distal
angle of the exopod and generally terminating a little or somewhat before it. In the female
the exopod is generally between four and four and a half times as long as broad; its terminal
margin (fig. 2 e) is considerably or very oblique, and the marginal tooth as in the male.

The petasma (figs. ig — 2/) is instantly distinguished from that in any other species by
the peculiar shape of its terminal portion. The membranous part [in. in figs. 2g and 2 //) is
seen overlapping a portion of the proximal part of the petasma, and it has a rounded angle.
The well chitinized part (ck.) of the terminal portion is rather curved with a large number of

6i

small, sharp tubercles on much of the inner side and especially on the major distal part of its
convex margin (figs. 2/1 and 22); before the end this chitinized part is somewhat narrow, and
the end itself is obliquely and distinctly expanded. The processus ventralis is somewhat flattened,
narrower at the base and broader towards the end which is somewhat incised and adorned with
a consequently bipartite brush of numerous short chitinous threads. The brush is frequently easy
to see without preparation, and the brush together with the distinctly widened plate-shaped end
•of the sheath are excellent speciiïc characters. — The protuberance (fig. 2g, pi) on the front
margin of the pleopod is oblong as in the preceding forms.

Length of a male 9.5 mm., of a female 10.8 mm.

Remarks. — The male can always be determined with certainty. Most frequently the
shape of the end of the üropods is sufficiënt, but in some specimens this end is not very
different from the shape sometimes found in L. intermedius or, rarely, L. Hanseni, and in such
cases an inspection of the shape of the petasma will instantly decide the question. But in some
cases I have found it impossible to decide whether a female belonged to L. penicillifer.

Distribu tion. — L. penicillifer is extremely common in the "Siboga" area, as it
has been taken at more than forty stations, in reality in the majority of the Plankton samples
containing specimens of the genus. And at a number of stations from a hundred to a thousand
specimens were taken, probably in the same haul. The Copenhagen Museum possesses specimens
from the Bay of Bengal ("Galathea" Exped.); at lat. 4°2o'N., long. io7°2o'E. (Capt. Andréa);
lat. i5°i4'X., long. n8°E. ("Galathea"); Formosa Strait ("Galathea"); Manilla ("Galathea");
Ghinese Sea, Hongkong- — Shanghai ("Galathea"), and Gulf of Yeddo ("Galathea").

5. Lucifer Faxonii Borrad. PI. V, figs. 2>a — 3*'-

1878. Lucifer typtest Faxon, Stud. Biol. Lab. Johns Hopkins Univ. 3, p. 113, PI. VII, [teste

Borradaile].
1882. Lucifer sp. Brooks, Phil. Trans. Roy. Soc. London, Vol. 173, I, p. Sj, Pis. 7 — 9, figs. 61 — 75.
1915. Lucifer faxoni Borradaile, Ann. Mag. Nat. Hist. Ser. 8, Vol. XVI, p. 228.

Stat. 66. May 7 — 8. Bank betvveen Bahuluwang and Tambolungan, South of Saleyer. S — 10 m.
Plankton. 12 specimens.

Stat. 98—99. June 28—30. Lat. 6° 9'— 6°/.$ N., long. I20°2i' — I20°26'E. Tovvnet. 14 spe-
cimens.

Stat. 117a. July 12. Lat. i°I5'N., long. 123° 37' E. Townet. 2 specimens.

Stat. 125. July 18 — 19. Anchorage off Sawan, Siau-island. 27 m. 4 specimens.

Stat. 136. July 29 — Aug. 3. Ternate anchorage. 23 m. Tovvnet. 1 specimen.

Stat. 13S. Aug. 3. Anchorage on the east coast of Kajoa-island. 66 m. Townet. Large number
of specimens.

Stat. 140. Aug. 4 — 5. Bay of Batjan. 13 m. Townet. 2 specimens.

Stat. 144. Aug. 7 — 9. Anchorage North of Salomakiëe-(Damar-)island. 45 m. Tovvnet. n spe-
cimens.

Stat. i77a. Sept. 1. Lat. 2°3o'S., long. I29°28'E. Tovvnet. 15 specimens.

Stat. 184. Sept. 11 — 12. Anchorage off Kampong Kelang, South coast of Manipa-island. 36 m.
Townet. 8 specimens.

Stat. 1S5. Sept. 12. Lat. 3° 20' S., long. I27°22'.9E. HENSEN vertical net, from 1536 m. depth
to surface. 1 specimen.

Stat. 189». Sept. 12. Lat. 2°22'S., long. i26°46'E. Townet. 2 specimens.

62

Stat. 194. Sept. 15. Lat. I°S3'.SS., long. I26°39'E. Townet. 21 specimens.

Stat. 194 — 197. Sept. 15. Lat. i°53'.5 — 1°45'-3 S., long. I26°39' — I27°8'.3E. Plankton. 5 spe-
cimens.

Stat. 203. Sept 19. Lat. 3°32'.sS., long. i24°i5'.sE. Hensen vertical net, from 1500 m.
to surface. 8 specimens.

Stat. 206. Sept. 21. Buton-strait. Surface. 1 specimen.

Stat. 216. Oct. 30. Lat. 6° 49' S., long. I22°43'E. 2190 m. FoWLER closing net, from 975 to
415 m. depth. 4 specimens.

Stat. 220. Nov. 1 — 3. Anchorage off Pasir Pandjang, west coast of Binongka. 278 m. Townet.
5 specimens.

Stat. 230. Nov. 14. Lat. 3°58'S., long. i2S°2o'E. Hensen vertical net, from 2000 m. depth
to surface. 1 specimen.

Stat. 245. Dec. 3. Lat. 40 i6'.5 S., long. i30°is'.8E. Townet. 12 specimens.

Near Stat. 300. Between Timor and Lomblen. Plankton. 3 specimens.

Description. — Eye-stalks with eyes shorter in proportion to the body than in L.
intermedius and conspicuously less than half as long as the distance between their insertion
and the labrum; the stalks increase gradually and considerably in thickness from the base to
the eye. First antennular joint in the male reaches somewhat beyond the front margin of the
eyes (fig. 3 a); in the females this joint is frequently proportionately still longer, and in such
cases it reaches very considerably beyond the eyes. In the male the two ventral processes on
sixth abdominal segment (fig. $ó) are shaped nearly as in L. intermedius, but the anterior
process is placed more backwards, consequently considerably more distant from the base of the
segment than from the second- process. Exopod of uropods in the male (fig. 3 è) about five
times as long as broad ; its terminal margin is slightly or rather considerably oblique (figs. 3 c
and 3</), and the marginal process, which varies much in size, reaches always in the "Siboga"
specimens to or, generally, beyond the upper distal angle of the exopod (as to the Atlantic
specimens see "Remarks"). In the female the exopod is almost as narrow as in the male, but
the terminal margin is always rather oblique, and the marginal process which is long (fig. 3^)
or short, does not always reach so far backwards as the upper distal angle.

The petasma (figs. $g — 3/) differs much from those in the preceding forms, but is rather
similar to that in L. Hanseni. lts terminal portion tapers gradually from the base to the acute
end; it is considerably curved, and a short part near the end is curved distinctly in the opposite
direction. Processus ventralis (J>v. in figs. 3// and 32) is shaped nearly as a needie, tapering to the
very acute end. The protuberance (/. in figs. 3^ and 3//) on the front margin of the pleopod
is as long as, or longer than, broad at the base, with some or several prickles on the end.

Length of a male 11 mm., of a female 11.5 mm.

Remarks. — L. Faxonii is in general aspect somewhat similar to L. intermedius, but
the males of both species differ generally distinctly from L. pcnicillifer in the shape of the
exopod of the uropods. Both sexes of L. Faxonii differ from the two species mentioned in the
length of the first antennular joint in proportion to the eyes, and this feature affords a fine
specific character. From Cruz Bay, St. Jan, West Indies, the Copenhagen Museum possesses a
large material; the males differ most frequently from the "Siboga" specimens in having the upper
distal angle of the exopod of the uropods reaching to or beyond the end of the marginal tooth,
but in a few specimens the tooth reaches beyond that margin as in most "Siboga" specimens.

63

As no other species with short eye-stalks is known from the whole Atlantic, the name
L. Faxonii given by Borradaile to the form figured by Faxon and Brooks and captured north
of the line in that Ocean can be applied with certainty.

Distribution. — The list of localities and number of specimens show that L. Faxonii
is moderately common in the major part of the "Siboga" area. The Copenhagen Museum pos-
sesses specimens from some places in the Atlantic: lat. 330 N., long. 470 W. ("Galathea" Exped.);
Cruz Bay, St. Jan, West Indies (Dr. Th. Mortensen) ; off Puerto Cabello (Commodore H. Ki.er);
lat. 4°3o'N., long. 2802O/W. (Hugo Muller); lat. 23°S., long. 420 W. (Jonas Beldring). -
The specimens from the Atlantic taken by the German Plankton-Expedition and referred by
Ortmann to L. typus belong certainly to the present species; on its occurrence Ortmann wrote
(op. cit. 1893, P- 41)» tnat m contradistinction to the other species (dealt with by me above as
the real L. typus H. M.-Edw.) it is "sehr lokalisiert: ausser je einem, offenbar versprengten
Exemplar im Floridastrom und der Sargasso-See (nahe Bermuda) fand er sich zahlreich an einer
bestimmten Stelle des südlichen Aequatorialstroms. (nahe Fernando Noronha) und massenhaft
auf der Küstenbank vor der Tocantins-Mündung".

6. Lucifer Hanseni Nobili. PI. V, figs. \a — 40.

1905. Lucifer Hanseni Nobili, Buil. Mus. d'Hist. Natur. 1905, n" 6, p. 394.

1906. Lucifer Hanseni Nobili, Ann. Sci. Natur., Zool. 9. ser., T. IV, p. 25 (with fig. 3), PI. II, fig. 1.

191 5. Lucifer inermis Borradaile, Ann. Mag. Nat. Hist. ser. S, Vol. XVI, p. 229.

1916. Lucifer hanseni Borradaile, Brit. Antarct. Exped., Crust. I, Decapoda, p. 83.

Stat. 7. March 11. Lat. 7°5S'.5S., long. ii4°26'E. 15 m. and more. 1 specimen.

Stat. 16. March 15 — 16. Bay of Kankamaraan, S. coast of Kangeang. 22 m. Electric light

in vertical net. 1 specimen.
(Stat. 26 — 32). March 23. Lat. 8°3,5'.i — 9°2' S., long. 1 I5°3i'.2 — 1 is°47'E. Surface. 1 specimen.
Stat. 35. March 28. Lat. 8°o'.3S., long. ii6°59'E. Surface. 6 specimens.
Stat. 2>7- March 30 — 31. Sailus ketjil, Paternoster-islands. 27 m. and less. 4 specimens.
Stat. 50. April 16 — 18. Bay of Badjo, West coast of Flores. Depth up to 40 m. Plankton.

3 specimens.
Stat. 66. May 7 — 8. Bank between Bahuluwang and Tambolungan, South of Saleyer. 8 — 10 m.

Plankton. Numerous specimens.
Stat. 71. May 10 — June 7. Makassar and surroundings. Depth up to 32 m. Townet. About

25 specimens. (Most of the specimens small with black eyes).
Stat. 9S — 99. June 28 — 30. Lat. 6° 9' — 6°7'.5 N., long. I20°2i' — i20°26'E. Townet. 2 specimens.
Stat. 99. June 28 — 30. Lat. 6° 7'. 5 N., long. i20°26'E. 16 — 23 m. Townet. Numerous specimens.
Stat. 104. July 2 — 3. Sulu harbour, Sulu-island. 14 m. Townet. 4 specimens.
Stat. 105. July 4. Lat. ó°8'N., long. I2I°I9'E. 275 m. Plankton. 2 specimens.
Stat. 106. July 4. Anchorage otï Kapul-island, Sulu-archipelago. Townet. Large number of

specimens.
t Stat. 109. July 5 — 6. Anchorage off Pulu Tongkil, Sulu-archipelago. 13 m. Townet. Many

specimens.
Stat. 128. July 22. Lat. 4°27'N., long. I25°25'.7E. 1645 m. HENSEN vertical net, from 700 m.

to surface. 1 specimen.
Stat. 136. July 29 — Aug. 3. Ternate anchorage. 23 m. Townet. Many specimens.
Stat. 13S. Aug. 3. Anchorage on the East coast of Kajoa-island. 66 m. Townet. 2 specimens.
Stat. 141. Aug. 5. Lat. i°o'.4S., long. I27°25'.3E. 1950 m. HENSEN vertical net, from 1500 m.

to surface. Many specimens.

64

Stat. 142. Aug. 5 — 7. Anchorage off Laiwui, coast of Obi Major. 23 m. Electric light in

vertical net. Very large number of specimens. (The specimens with black eyes).
Stat. 143. Aug. 7. Lat. i04-5 S., long. i27°52'.6E. 1454 m. Hensen vertical net, from 1000 m.

to surface. 2 specimens.
Stat. 144. Aug. 7 — 9. Anchorage North of Salomakiëe-(Damar-)island. Townet. Numerous

specimens.
Stat. 146. Aug. 9. Lat. o°36'S., long. I28°32.7E. 512 m. Townet. 2 specimens.
Stat. 157. Aug. 15 — 16. Lat. o° 32'.9 S., long. I30°I4'.6E. 45 m. Townet. 10 specimens.
Stat. 165. Aug. 20 — 22. Anchorage on North-east side of Daram-island, East coast of Misool.

49 m. Townet. 2 specimens.
Stat. 168. Aug. 22 — 23. Anchorage North of Sabuda-island. 63 m. Townet. 1 specimen.
Stat. 174. Aug. 28 — 29. Waru-bay, North coast of Ceram. 18 m. 2 specimens.
Stat. I77a. Sept. 1. Lat. 2°3o'S., long. 129° 28' E. Townet. Many specimens.
Stat. 184. Sept. 11 — 12. Anchorage off Kampong Kelang, South coast of Manipa-island. 36 m.

Townet. 3 specimens.
Stat. 185. Sept. 12. Lat. 3°2o'S., long. I27°22'.9E. Manipa-strait. Hensen vertical net, from

1536 m. to surface. 4 specimens.
Stat. 189a. Sept. 12. Lat. 2°22'S., long. i2Ó°46'E. Townet. 15 specimens.
Stat. 194. Sept. 15. Lat. i°53'.sS., long. I26°39'E. 1504 m. Townet. 17 specimens.
Stat. 194—197. Sept. 15. Lat. i° 53.5 — 1°45'.3 S., long. I26°39'— 127°8'.3 E. Plankton. 2 spe-
cimens.
Stat. 203. Sept. 19. Lat. 30 32.5 S., long. i24°is'.5E. Hensen vertical net, from 1500 m. to

surface. 8 specimens.
Stat. 206. Sept. 21. Buton-strait. Surface. 2 specimens.
Stat. 216. Oct. 30. Lat. 6°49'S., long. I22°43'E. 2190 m. Fowler closing net, from 975 to

415 m. depth. 2 specimens.
Stat. 220. Nov. 1 — 3. Anchorage off Pasir Pandjang, West coast of Binongka. 278 m. Townet.

1 specimen.
Stat. 223. Nov. 6. Lat. 5°44'.7 S., long. I2Ó°27'.3E. 4391 m. Surface. 1 specimen.
Stat. 225. Nov. 8. 5700 M. N. 2790 E. from Southpoint of South-Lucipara-islands. 894 m.

Horizontal cylinder. 30 specimens.
Stat. 245. Dec. 3. Lat. 4° 16.5 S., long. 130° 15.8 E. 4956 m. Townet. 7 specimens.
Stat. 276. Jan. 9. Lat. 6°47'.5 S., long. i28°4o'.5 E. Hensen vertical net, from 750 m. to

surface. 2 specimens.
Near Stat. 300. Between Timor and Lomblen. Plankton. 3 specimens:
Stat. 315. Febr. 17 — 18. Anchorage East of Sailus Besar, Paternoster-islands. Surface. 1 specimen.

Description. ■ — This species shows some variation in various particulars. Eye-stalks
with eyes vary from a little more to conspicuously less than half as long as the distance between
their insertion and the labrum (fig. 4 a); the stalks nearly as in L. penicillifer, as sometimes
they are conspicuously inverted conical, and sometimes increasing feebly in thickness to near
or beyond the middle. First antennular joint in both sexes either reaches a little beyond the
eyes or, and perhaps most frequently, it is proportionately shorter, reaching to (fig. 4a) or not
fully to the front margin of the eyes. Sixth abdominal segment in the male somewhat (fig. 4Ó)
or, most frequently, much deeper (fig. 4X') in proportion to its length than in the preceding
forms; the first ventral process is much shorter than the second, and sometimes quite small
(fig. 4/Ê); besides it is always distinctly nearer to the second process than to the base of the
segment, and in most males the distance between the median point in the base of the two
processes is about half, or even only one-third, as long as the distance from the base of the
segment to the first process ; second process tapers always to the obtuse end, but it varies

considerably in thickness. In the female the sixth segment is alsu proportionately deeper than
in the other species. That the telson varies in shape is shown in figs. \h and 4/, representing
that appendice in two males from the same station. In the male the exopod of the uropods is
observed in specimens from the same locality to vary from being four and a half times as long
as broad, but generally it is only slightly or somewhat more than four times as long as broad;
the upper distal angle of the exopod reaches alvvays beyond the end of the marginal tooth
which is small, and excepting in a few small specimens (fig. xf) this tooth is placed much
(fig. ac) or very much (fig. \d) in advance of the upper distal angle. In the female the exopod
is about four times as long as broad, and the marginal tooth is placed far before its end
(figs. \e and \g).

The petasma (figs. 4/ — 4-0) is rather similar to that in L. Faxonii. lts terminal portion
is proportionately shorter; its acute or subacute end less produced and it is not curved in the
opposite direction towards the end. The processus ventralis {jro. in figs. \u and xo) has its distal
half shaped as a curved, acute needie differing somewhat in shape from that in L. Faxonii.
The protuberance on the front margin of the pleopod generally short (p. in figs. 4/ and xm)
and very broad in proportion to its length, with several or many prickles.

Length of a male 9 mm., of a large female 11.6 mm.

Remarks. — Nobili's figures and his footnote on p. 27 (1. c.) are sufficiënt for
recognizing the species with certainty. As already pointed out in the description, it shows not
inconsiderable individual variation, and one curious point is not mentioned above. In the spe-
cimens from nearly all the "Siboga" stations the eyes are light opaque or brownish, but in the
hundreds of specimens from Stat 142 the eyes are internally partly or totally black, and the
same colour is also found in some specimens from Stat. 71,411 numerous specimens from Colombo
gathered in 1898 and even in some specimens secured by the "Galathea" Expedition more
than seventy years ago. One is tempted to think that the difference in the colour of the eyes
might be a specific character, but in spite of a good deal of trouble I have been unable to
find any other character, not even in the petasma, and the variation found in other features
was independent of the colour of the eyes.

Distribution. — The long- list of localities shows that L. Hanseni has been taken
at almost as many places in the "Siboga" area as L. penicillifer, but the number of specimens
of L. Hanseni is, taken as a whole, ver)- much lower, probably not one-third as large as of
L. penicillifer. Nobili established L. Hanseni on specimens taken at Djibouti (the Red Sea),
and Borradaile records numerous specimens gathered in Melbourne harbour. The Copenhagen
Museum possesses specimens from Colombo, Ceylon (Mr. H. Mortensen); the Bay of Bengal
("Galathea" Exp.); Lower India, and the Chinese Sea ("Galathea"). Consequently it has a very
wide distribution in the Indian Ocean and in at least a considerable part of the Pacific.

EXPLANATION OF THE PLATES.

PLATE I.

In all figures representing the male petasma or the distal half of its pars media the following lettering
is used. a. pars astringens; e. pars externa; lam. lamina externa of pars externa; pu. processus uncifer of
pars externa; m. pars media; pb. processus basalis; pv. processus ventralis; la. lobus armatus ; Ie. lobus
connectens; li. lobus inermis; //. lobus terminalis; lac. lobi accessorii.

Fig. I. Ser gestes inous Faxon.

Fig. i a. Left petasma, from behind ; X /■

Fig. 1 b. Distal portion of pars media of the same petasma, from behind; X 19.

Fig. ir. Distal portion of pars media of the same petasma, from in front; X 19.

Fig. 2. Ser gestes G ar diner i Kemp.

Fig. 2a. Left petasma, from behind; 20.

Fig. 2b. Distal portion of pars media of the same petasma, from behind ; X 40.

Fig. 2c. Distal portion of pars media of the same petasma, from in front; X 40.

Fig. 3. Sergestes bisitlcatus Wood-Mason.

Fig. 3#. Front end of the carapace of a female, from the left side ; X 6.

Fig. 3<5>. Left petasma, from behind; X 13-

Fig. 2>c- Distal portion of pars media of the same petasma, from behind; X 30.

Fig. T,d. Distal portion of pars media of the same petasma, from in front; X 30.

Fig. 4. Sergestes Challengeri H. J. H.

Fig. 4a. Front end of the carapace of a female, from the left side; X 13.

Fig. 4b. Right eye-stalk with eye of a female from Stat. 46a, from above; X 23/2-

Fig. 4c Third joint of left antennular peduncle with the proximal parts of the two flagella of a male from

Stat. 185, from the left side; X 15-

Fig. \d. Third joint of left antennular peduncle of another male from Stat. 185, from the left side; X '^/^

Fig. 4e. Third joint of left antennular peduncle of a female, from the left side; X 2%-

Fig. 4/. Distal portion of pars media of left petasma of a male from Stat. 185, from behind; X 32.

Fig. 4g. Same distal portion of pars media of left petasma, from in front; X 32.

Fig. 4/1. Distal half of processus uncifer of the same petasma, from behind ; X 32.

Fig. 41. Antenor part of a very young specimen, 13.3 long, from Stat. 143, from above; X 13.

Fig. 4k. Exopod of left uropod of a Mastigopus, 12.3 mm. long, from the outer side; X 14.

Fig. 4/. Anterior part of a Mastigopus, 12.3 mm. long, from Stat. 148, from the left side; X 13. a. rostrum; X 32.

Fig. 5. Sergestes sp.

Fig. 5«. Third joint of left antennular peduncle with the proximal parts of both flagella of an adult male
from Stat. 100, from the outer side; X 9-

Fig. 6. Sergestes fulgens n. sp.

Fig. 6a. Anterior part of the carapace with left eye and the basal parts of antennula and squama of a

male, from the left side; X 6.
Fig. 6b. Third joint of left antennular peduncle with the lower flagellum and the proximal part of the

upper flagellum of an adult male, from the left side ; X 9-
Fig. 6c. Proximal half (the clasping organ) of the lower flagellum of the same antennula, from the outer

side; X 24.
Fig. 6d. Distal part of third maxilliped of a male; X 14. The terminal setae wanting.
Fig. 6e. Left petasma, from behind; X 12.

Fig. 6/. Distal portion of pars media of the same petasma, from behind; X 22.
Fig. 6g. Same distal portion of pars media of left petasma, from in front; X 22.

Fig. 7. Sergestes seminudus n. sp.
Fig. ja. Left petasma, from behind; X 16.

Fig. jb. Distal half of pars media of the same petasma, from behind; X 31.
Fig. 7<\ Distal half of the same pars media of left petasma, from in front; X 31.

SibogcL-Expe-clttte.. X.XXVHL H. J Hatts en. Sorgesttdoe.

PI .

f! .' M ' ans*n dfl .

1 Seiyestes inous Saam. 2 S Gardaierv K„mp. 3. S bUuJcatus W,od,-Mz*,n. j S ChaZlengerL Tf.J.H.

S. SergesteS sp. , J 6S.ful<jensn.sP. 7. S. semimidus n-rf. T.KHoUvr to-

PLATE II.

Fig. i. Sergestes seminudus n. sp. (Continued).
Fig. ia. Sixth joint and distal part of fifth joint of third maxilliped ; X 12.
Fig. \b. Distal part of first thoracic leg; >< 12.
Fig. 1 c. Carapace, anterior appendages and the two anterior abdominal segments of an Acantliosoma, from

above; >< scarcely 16. The four processes on right half of the carapace and the distal part of

the antennas omitted. <z.' antennula; a.2 antenna; sq. squama.
Fig. ld. Carapace, left eye and proximal parts of left antennula and antenna of another Acantliosoma, from

the left side ; X 34- s1- squama.
Fig. ie. Dorsal part of the five anterior abdominal segments of an Acantliosoma, from the left side; >< 30.
Fig. if. Terminal part of sixth abdominal segment, telson and left uropod of an Acantliosoma, from above; X 35-

Fig. 2. Sergestes orientalis n. sp.
Fig. 2a. Front end of the carapace of a male, from the left side; X 14.
Fig. 2b. Lower flagellum of right antennula of a male, from the outer side; X 35-
Fig. 2.c. Left third maxilliped — the basal joint omitted — of a male, from the outer side; X 9- <*■• the

six subjoints of sixth joint and the end of fifth joint; X 20.
Fig. 2d. First left thoracic leg of the same male, from the outer side; X 9-
Fig. 2e. Distal part of the same first thoracic leg, from the outer side; X 34.
Fig. 2/". Fourth left thoracic leg of the same male, from the outer side; X 9-
Fig. 2g. Left petasma, from behind ; ; 30. a. pars astringens ; lam. lamina externa, and pu. processus

uncifer, both portions of pars externa; pb. processus basalis.
Fig. 2 h. Distal portion of pars media of the same petasma, from behind; X 48. la. lobus armatus, bifurcate;

Ie. lobus connectens; li. lobus inermis; It. lobus terminalis; lac. lobus accessorius; pv. processus

ventralis.
Fig. 2z. Same distal portion of pars media of left petasma, from in front; X 48. The lettering as in fig. 2/1.
Fig. 2k. Distal portion of pars media of left petasma of a male from lat. 190 14' N., long. 116° 6' E., from

behind; X 47. The lettering as in fig. 2/1.
Fig. 2/. Carapace with eyes, major part of the antennulae, and antennal squamae of a Mastigopus, 4.3 mm.

long, from above; X 16.
Fig. 2m. Distal part of left third maxilliped of a Mastigopus, 10.8 mm. long, from the outer side, X 22.
Fig. 211. Sixth abdominal segment with telson and left uropod of a young Mastigopus measuring 3.3 mm.,

from the left side ; X 23. Setas on the upper margin of the exopod omitted.
Fig. 20. Carapace with eyes, antennula;, antennal squamas and first abdominal segment of an Acantliosoma,

from above; X 20. «.' antennula; sq. squama.
Fig. 2p. Carapace with left eye, antennula, antennal squama and proximal part of antennal flagellum of

another Acantliosoma, from the left side ; X 20.
Fig. 2q. Posterior part of sixth abdominal segment with telson and left uropod of the Acantliosoma shown

in fig. 20, from above; X 32.

Fig. 3. Sergestes Edwardsii Kr.
Fig. 3a. Distal portion of pars media of left petasma of a specimen from the Atlantic at lat. 3°9' N., long.
23°ii'W., from behind; X 47- The lettering as in fig. 2/1.

Fig. 4. Sicyonella maldivensis Borradaile.
Fig. 4a. Anterior right part of carapace with eye, antennula and antennal squama of a male from Stat. 164,

from above ; X 9-
Fig. 4b. Anterior right part of carapace with eye, antennula and antennal squama of a female from Stat. 164,

from above ; X 9-
Fig. 4c. Terminal part of right antennular peduncle with the proximal parts of both flagella of a male,

from the inner side; X 24.
Fig. 4d. Distal joints of first thoracic leg of a female, from below; X 22.
Fig. 4e. Left petasma, from behind; '/ 21. a. pars astringens; lam. lamina externa, and pu. processus

uncifer, of pars externa.
Fig. 4/. Distal half of pars media of the same petasma, from behind; X 42. la. lobus armatus; Ie. lobus

connectens; It. lobus terminalis; pv. processus ventralis, ramified (see text).
Fig. 4g. Same distal portion of pars media of the petasma, from in front; X 42. The lettering as in fig. 4/'.

Fig. 5. Sicyonella antennata n. sp.
Fig. 5#. Terminal part of right antennular peduncle with the proximal parts of both flagella of a male,

from the outer side; X 21.
Fig. 5^. Distal joints of first thoracic leg of a female, from below; X 20.
Fig. 5 f. Distal part of third thoracic leg of the same female; X 20.

Sïboga i:\-r-.liii,- XXXVID S.J.HA2fSEK. Sergestidoe.

/'/ //

// .1 II,:,:,-,, .!■■!

_/ Se r;[.*.K/ ,■ x ï,'n, i tiuili/.v n sp. 2.S. "r/ril tn li.v n sp 3. S.JZdbmaprïLsvi Ar.

l[. Siayorv&ïla m >i ■/ </; r>r n»ris fiot-fod .7 Sic a n h-u ti ,i l u n j-p.

i \ \i..iifT .«.-

PLATE III.

Fig. i. Sicyonella antennata n. sp. (Continued).

Fig. ia. Anterior part of an adult male, from above; X 7-

Fig. ib. Anterior right part of carapace vvith eye, antennula and squama of an adult female, from Stat. 258,

from above ; X 9-
Fig. ie. Exopod of left uropod of a male; X scarcely 7.
Fig. ld. Left petasma, from behind ; X 20. a. pars astringens; lam. lamina externa, and pu. processus

uncifer, of pars externa.
Fig. ie. Distal half of pars media of the same petasma, from behind; X 38. la. lobus armatus ; Ie. lobus

connectens; ? li, probably lobus inermis; //. lobus terminalis; lac. lobus accessorius; pv. processus

ventralis, cleft into two main branches.
Fig. \f. Same distal half of pars media of the petasma, from in front; X 38. The lettering as in fig. ie.

Fig. 2. Acetes vulgaris n. sp.

Fig. 2a. Anterior part of a male, from above; X i3/%-

Fig. 2b. Anterior right part of carapace with eye, antennula and squama of an adult female from the Gulf

of Siam, from above; X 13/i>-
Fig. 2c. Front end of the carapace of a female, from the left side; X 17.

Fig. 2d. Proximal part of left lower antennular flagellum of a male, from the outer side; X 33-
Fig. 2e. Left mandible of a male, from belovv; X 14-
Fig. 2/. Left maxillula of the same male, from below ; X 14.
Fig. 2g. Left maxilla of the same male, from below; X H- P- palp.

Fig. 2/1. Left first maxilliped of the same male, from below; X 14. ep. epipod ; ex. exopod.
Fig. 2z'. Left second maxilliped of the same male, from behind; X 14. br. branchia; ep. epipod.
Fig. 2k. Distal part of left third maxilliped of the same male; X 23.
Fig. 2/. Distal part of left first thoracic leg of the same male; X 23.
Fig. 2111. Left uropod of a male, from the outer side; X 7-

Fig. 211. Posterior part of thorax of a male, from below; X II. I.3 third thoracic leg; ge. genital coxse.
Fig. 20. Posterior part of thorax of a female, from below; X II. s.* fourth (penultimate) thoracic segment;

.f.5 fifth (last) thoracic segment.
Fig. 2p. Left petasma, from behind; X 22. a. pars astringens; e. pars externa.
Fig. 2q. Distal portion of pars media of the same petasma, from behind; X5I- c. capitulum ; pv. processus

ventralis.
Fig. 27'. Distal portion of pars media of the same petasma, from in front; X 51- c- capitulum; pv. processus

ventralis.

Fig. 3. Acetes sp.
Fig. 3«. Distal portion of pars media of left petasma of a male from Stat. 47, from in front; X 44-

Fig. 4. Acetes Sibogte n. sp.

Fig. 4a. Anterior part of the carapace with right eye, antennula and squama of a male, from above; X 9-
Fig. 4b. End of third peduncular joint of left antennula with lower flagellum and the proximal part of

upper flagellum of a male, from the outer side; X 38.
Fig. 4c. Exopod of left uropod of a male; X il.
Fig. ^d. Posterior part of thorax of a male, from below ; X 13-
Fig. 4e. Posterior part of thorax of a female, from below; X 13-
Fig. 4/. Left petasma, from behind; X 28.
Fig. 4g. Distal half of pars media of the same petasma, from behind; X 46. c. capitulum; pv. processus

ventralis.
Fig. 4I1. Same distal half of pars media of the petasma, from in front; X 46. The lettering as in fig. 4g.

Fig. 5. Acetes dispar n. sp.
Fig. 5rt. Anterior part of the carapace with right eye, antennula and squama of a male from Cheribon

(Java), from above; X II.
Fig. $b. End of third peduncular joint of left antennula with the lower flagellum and the proximal part

of upper flagellum of a male from Siam, from the outer side; X 39-
Fig. 5c. Exopod of left uropod of a male; X 14-
Fig. i,d. Posterior part of thorax of a male, from below; X 35/s-

Fig. 5^. Left petasma, from behind; X 32. c. capitulum; e. pars externa; pv. processus ventralis.
F'g- 5/- Distal portion of pars media of the same petasma, from behind ; X 66.

Sïbogw-ZxpeMtie AXYVJ1I H.J.KAMSEN, Sergestidoe.

VI. III.

Ju

LSieyone.Ua antennaM n.y ZAcetes imlgwrLr juap. :!,h •■!■:<■ *p. y d Sii, ■.,/./• ».. sP.

IIJII.J„so-n del. ■' ' '/'•"'/""• " -V>

TV.MeUer te.

PLATE IV.

Fig. I. Acetes dispar n. sp. (Continued).
Fig. ia. Postcrior part of thorax of a female, from below ; X 21.

Fig. 2. Acetes dispar var. vel sp. n.
Fig. 2a. Posterior part of thorax of a female from lat. 240 17' N., long. ii8°I5'E., from below; X <3-

Fig. 3. Acetes cltinensis n. sp.
Fig. 3«. Exopod of left uropod of a female; X 7-
Fig. ib. Posterior part of thorax of a female, from below; X 13.

Fig. 4. Acetes serridatus Kröyer.
Fig. 4a. Anterior part of the carapace with the right eye, antennula and antenna of a male, from above; X 9-
Fig. 4b. Front end of the carapace of a female, from the left side; X 29.
Fig. 4c. End of third peduncular joint of left antennula with lower flagellum and the proximal part of

upper flagellum of a male, from the left side; X 39-
Fig. 4d. Exopod of left uropod of a male; X II-

Fig. 4e. Posterior part of thorax of a male, from below; X 27/r ge. genital coxae.
Fig. 4 f. Posterior part of thorax of a female, from below; X 15-

Fig. 4g. Left petasma, from behind; X 33- c. capitulum ; e. pars externa; m. pars media.
Fig. 4/1. Capitulum of the same petasma, from behind; X 72.

Fig. 5. Acetes spiniger n. sp.
Fig. 5«. Anterior part of carapace with right eye, antennula and squama of a male, from above; X scarcely 7.
Fig. 5$. Front end of the carapace of a male, from the left side; X 29.
Fig. 5 c End of third peduncular joint of left antennula with lower flagellum and the proximal part of

upper flagellum of a male, from the outer side; X 30.
Fig. $d. Exopod of left uropod of a male; X 9.

Fig. 5 r. Posterior part of thorax of a male, from below; X 13. ge. genital coxae.
Fig. 5/. Posterior part of thorax of a female from Surabaya (Java), from below; X 10.
Fig- Sg- Left petasma, from behind; X 22. e. pars externa; c. capitulum; pv. processus ventralis.
Fig. 5 h. Distal half of pars media of the same petasma, from behind ; X 38. c. capitulum ; pv. processus ventralis.

Fig. 6. Lucifer typits H. M.-Edw.

Fig. 6a. Posterior part of abdomen with left uropod of a male from lat. 5°3i ' N., long. 23°i5'W., from

■the left side; X scarcely 17.
Fig. 6b. Terminal part of the exopod of the uropod shown in fig. 6a; X 50.
Fig. 6c. Terminal part of the exopod of left uropod of another male; X 50.

Fig. 6d. Terminal part of the exopod of left uropod of a female from the same locality in the Atlantic; X 50.
Fig. 6e. Telson of a male from the same locality, from the left side; X 43-
Fig. 6/. Telson of another male from the same locality, from the left side; X 43.
Fig. 6g. Major part of the peduncle of first left pleopod of a male from lat. 5°3i'N., long. 23°i5'W.,

from the inner side; X 78. The petasma is partly unfolded and its rather narrow terminal

portion removed from the pleopod. p. process at the margin of the pleopod beyond the petasma.
Fig. 6/1. Terminal portion of the same petasma drawn with transmitted light so that the strongly chitinized

parts are rendered with dark shading; X 160. h. long-stalked hook; pv. processus ventralis;

s. dark undulating transverse lines.
Fig. 6i. Terminal portion of another petasma drawn with transmitted light, and processus ventralis has

been taken out; X 160. The lettering as in fig. 6/1.
Fig. 6k. Terminal portion of a third petasma, seen from behind; X 160. The processus ventralis, pv., has

been turned out of the sheath, s/i. ; //. hook.

Fig. 7. Lucifer orientalis n. sp.

Fig. ja. Posterior part of abdomen with left uropod of a male from Stat. 203, from the left side; 14.

Fig. jb. Terminal part of the exopod of the uropod shown in fig. ja; X 50.

Fig. je. Terminal part of the exopod of left uropod of a female; X SO.

Fig. jd. Telson of a male, from the left side; X 43-

Fig. je. Peduncle of first left pleopod of a male from Stat. 203, from the inner side; X 54- The petasma
is partly unfolded and its narrower terminal portion removed from the pleopod. p. process at
the margin of the pleopod.

Fig. jf. Terminal portion of the same petasma drawn with transmitted light; X 160. pv. processus ven-
tralis; s. transverse lines.

Fig. j g. Terminal portion of another petasma, seen from behind, and the processus ventralis, pv., has been
turned completely out of the sheath; 160.

Fig. 8. Lucifer intermedius n. sp.

Fig. 8a. Front end of cephalothorax with left eye, antennular peduncle, and basal part of antenna with

squama, sa., of a male from Stat. $J, from the left side; , 21.
Fig. Sb. Telson of a male, from the left side; X 40.

Sïboga ~ExpedUte V.Y.VVIH IL.MLvxnkk Serg-estidoe

/'/ IV

/ .1 ,'tes cbisjHiv rv.sp. SAtüspar var.vel sy.rv. 3A.ch>Ti£TisLs n..ip. 4- Ase.vi-uXa.tus Kt. SA.spi.iviqer-n.nf.
HJII„„..„ .1.1 t' lutïifei- typus TI.ÏÏ-Mm 7. L. orierUaZiS n.sp 8.L. Lntert>ie.dius n sp. f \.U,.lUr *

PLATE V.

Fig. i. Lucifer intermedius n. sp. (Continued).

Fio-. \a. Posterior part of abdomen with left uropod of a male from Stat. 37, from the left side; X iali-

Fig. 1 b. Terminal part of the exopod of the uropod of the same male ; X 60.

Fig. \c. Terminal part of the exopod of left uropod of another male from Stat. 37; X 60.

Fig. id. Terminal part of the exopod of left uropod of a female from Stat. 37; X 60.

Fig. ie. Major part of the peduncle of first left pleopod of a male from Stat. 37, from the inner side; X 74- The petasma
is in its normal position, with its terminal portion across the peduncle. /. two protruding plates or lamella?;
m. membranous part of the sheath ; p. process at the margin of the pleopod.

Fig. 1 ƒ. Uistal third of left petasma, drawn with transmitted light, so that the strongly chitinized parts have dark shading,
and seen from the inner side; X 17°- l- two protruding plates; ///. membranous part of the sheath; pv. pro-
cessus ventralis; s. fine dark transverse lines.

Fig. ig. Distal third of another petasma seen mainly from the outer side; X 170. /. two protruding plates; pv. processus
ventralis, turned out of the sheath.

Fig. 2. Lucifer penicillifer n. sp.
Fig. 2<7. Front end of cephalothorax with left eye, antennular peduncle, and basal part of antenna with squama, of a

male, from the left side; X 22.
Fig. 2b. Posterior part of abdomen with lelt uropod of a male from Stat. 109, from the left side; X 18.
Fig. 2 c. Terminal part of the exopod of the uropod of the same male; X 54-
Fig. 2</. Terminal part of the exopod of left uropod of another male; X 54-
Fig. 2t'. Terminal part of the exopod of left uropod of a female; X 54-
Fig. 2/. Telson of a male, from the left side; X 52.
Fig. 2g. About half of the peduncle of first left pleopod of a male from Stat. 109, from the inner side; X 78. The petasma

is in its natural position, with its terminal portion across the pleopod. c/i. strongly chitinized distal part of

the sheath; m. membranous part of the sheath; p. process on the peduncle.
Fig. 2 li. Distal third of left petasma drawn with transmitted light and seen from the inner side; X 180. ch. strongly

chitinized scabrous part of the sheath ; 111. membranous part of the sheath ; pv. processus ventralis.
Fig. 2/. Terminal portion of another left petasma, from the outer side; X 180. ch. strongly chitinized scabrous part of

the sheath; pv. processus ventralis, turned out of the sheath.
Fig. 2k. Processus ventralis of a fourth petasma showing its end to be bipartite; X *So.

Fig. 3. Lucifer Faxonii Borrad.

Fig. 3«. Front end of cephalothorax with left eye, antennular peduncle, and basal part of antenna with squama, of a
male from Stat. 184, from the left side; X 23.

Fig. 3 b. Posterior part of abdomen with left uropod of a male from the same locality, from the left side; X 12.

Fig. 3<r. Terminal part of the exopod of left uropod of a male; X 4°-

Fig. 7>d. Terminal part of the exopod of left uropod of another male; X 4°-

Fig. 3 c. Terminal part of the exopod of left uropod of a female from the same station ; X 4°.

Fig. 3/. Telson of a male, from the left side; X 35-

Fig. 3"-. Major part of the peduncle of first left pleopod of a male from Stat. 184, from the inner side; X 78- The
petasma is in its natural position, with its terminal portion across the pleopod p. process on the peduncle.

Fig. 3/1. Distal third of the petasma removed from the pleopod, of which a small part together with a small portion of
the broad part of the petasma is shown, from the inner side; X i4°- A process on the peduncle; pv. pro-
cessus ventralis visible through the sheath.

Fig. 3/. Terminal portion of the petasma of another male, from the inner side; X J7°- cl>- strongly chitinized distal
part of the sheath ; ///. membranous part of the sheath ; pv. processus ventralis turned out of the sheath.

Fig. 4. Lucifer Hanseni Nobili.

Fig. 4a. Anterior half of cephalothorax of a male (black-eyed specimen) from Stat. 142, from the left side; X iS.

Fig. 4b. Posterior part of abdomen with left uropod of a male from Stat. 142, from the left side; X 18.

Fig. 4c. Terminal part of the exopod of left uropod of a male from the same station; X 48-

Fig. 4d. Terminal part of the exopod of left uropod of another male from the same station; X 48.

Fig. 4e. Terminal part of the exopod of left uropod of a female from the same station; X 4§.

Fig. 4/. Exopod of left uropod of a quite small, perhaps scarcely adult male, 7 mm. long, from the same locality, viz.
Stat. 142; X 3°-

Fig. 4g. Exopod of left uropod of a young female, 5.7 mm. long, from the same locality; X 33-

Fig. 4/1. Telson of an adult male from the same station, from the left side; X 43-

Fig. 4/. Telson of another adult male from the same station, from the left side; X 43-

Fig. 4k. Sixth abdominal segment of a male (with the eyes yellowish brown) from Stat. 106, from the left side; X 16.

Fig. 4/. Part of the peduncle of first left pleopod of a male from Stat. 106, from the inner side; X 77- The petasma is
almost in its natural position, as its distal part is on the figure turned only slightly to the left. p. process on
the peduncle.

Fig. 4111. Peduncle (the basal part omitted) of first left pleopod of a male from Stat. 142, from the inner side; X 80.
The petasma is unfolded, so that its distal half is parallel with the peduncle. p. process on the peduncle.

Fig. 411. Distal half of the petasma exhibited in fig. 4//1 and drawn with transmitted light, from the inner side; X 160.
c/i. strongly chitinized part of the sheath ; pv. processus ventralis.

Fig. 40. Terminal portion of the petasma of another male from the same station, from the inner side; X 160. pv. pro-
cessus ventralis, turned out of the sheath, sh.

Siiuya Expeditie. XXXVIJI. 11 J '.HANSKN, Sergestidce.

l7>

ld

Ir

1&

2a

-,■

2<l

W

3J

'Sc

if

Ifn-

/■•'

Kt

iLJ llansen d&l .

1. Lucifer iiiLerm.e.Aiu^s n.sp. 2. L. penieiXtifer n,.tp. 3 L.Fa.-voiiii /Jo,-,„<?

±. L. llanseiii NbiiU .

T. N.iKller sa

Livr. LXXXVI.

RESULTATS DES EXPLORATIONS
ZOOLOGIQUES, B0TAN1QUES, OCÉANOGRAPHIQUES ET GÈOLOGIQUES

ENTBEPRISKS AUX
CNDE3 NÉERLANDAISES OEIENTALES en 1899 — 1900,

a bord du 8IBOGA

SOUS LE COMMANDEMENT DE

G. ?. TYDEMAN

PUBLIÉS PAR

MAX WKBKR,

Chef de 1'expédition.

*I.

*II.

*1I1.

IV.

*Vfbis.

V.

*VI.

*VII.

*VIII.

*IX.

*x.

*XI.

*XII.

*XIII.

*XIV.

*xv.

*XVI.

*XVII.

XVIII.

XIX.

*xx.

*XXI.

XXII.

XXIII.

*XXIV'.

XXI VJ.

«XXV.

*XXVI.

«XXVItó.

XXVII.

♦XXVIII.

*XXIX.

*XXX.

*XXXI.

*XXXII.

XXXIII.

«XXXIV.

XXXV.

«XXXVI.

«xxxvn.

♦XXXVIII.

* XXXIX.

«XL.

XLI.

«XLII.

«XLIII.

«XLIV.

*XLV.

«XLVI.

«XLVII.

«XLVIII.

«XLIXi.

«XLIX2.

*L.

«LI.

«Lil.

«lui.

«LIV.

LV.

*LVI.

«LVU.

lvhl

*LIX.
«LX.
«LXI.
«LXII.
LXIII.
LXIV.
«LXV.
LXVI.

Introduction et description de 1'expédition, Mai Web er.
Le bateau et son équipement scieutifique, G. F. Tydeinan.
Résultats hydrographiques, G. F. Tydeman.
Foraminifera, (F. W. Winter f)-
Xenophyophora, F. E. Schulze.
Radiolaria, M. Hartmann.
Porifera, G. C. J. Vosmaer et I. Ijima ').
Hydropolypi, A. Billard1).

Stylasterina, S. J. Hickson et M'lo H. M. England.
Siphonophora, M"es Lens et van Riemsdijk.
Hydromedusae, O. Maas.
Scyphomedusae, O. Maas.
Ctenophora, M'le F. Moser.

Gorgonidae, Alcyonidae, J. VerBluys, S. J. Hickson,
[C. C. Nutting et J. A. Thomson ').
Pennatulidae, S. J. Hickson.
Actiniaria, P. Mc Murrich1).
Madreporaria, A. Alcock et L. Dödcrlein1).
Antipatharia, A. J. van Pesch.

Tarbellaria, L. von Graff et R. R. von Stummer.
Cestodes, J. W. Spengel.
Nematomorpha, H. F. Nier9trasz.
Chaetognatha, G. H. Fowler.

Nemertini, (A. A. W. Hubrech t f) et Mme G. Stiasny.
Myzostomidae, R. R. von Stummer.
Polychaeta errantia, R. Horst1).
Polychaeta sedentaria, M. Ca uil e ry et F. Mesuil.
Gephyrea, C. Ph. Sluiter.
Enteropneusta, J. W. Spengel.
Pterobranchia, S. F. H arm er.
Brachiopoda, J. F. van Bemmelen.
Polyzoa, S. F. Harmer ').
Copepoda, A. Scott1).
Ostracoda, G. W. Muller.
Cirripedia, P. P. C. Hoek.
Isopoda, H. F. Nierstrasz ').
Amphipoda, Ch. Pérez.
Caprellidae, P. May er.
Stomatopoda, H. J. Hans en.
Cumacea, W. T. Cal man.
Schizopoda, H. J. Hans en.
Sergestidae, H. J. Hansen.

Ilecapoda, J. G. de Man, J. E. W. Ihle et J. J. Tesch ').
Pantopoda, J. C. C. Loman.
Halobatidae, J. Th. Oudemans.
Crinoidea, L. Dóderlein et Austin H. Clark.
Echinoidea, J. C. H. de Me ij e re.
Holothurioidea, C. Ph. Sluiter.
Ophiuroidea, R. Kohier.
Asteroidea, L. Doder lei n ').
Solenogastres, II. F. Nierstrasz.
Chitonidae, H. F. Nierstrasz.
Prosobranchia, M. M. Schep man.

Prosobranchia parasitica, H. F. Nierstrasz et M. M.
Opisthobranchia, R. Bergh. [Schep man.

Heteropoda, J. J. Tesch.
Pteropoda, J. J. Tesch.

Lamellibranchiata, P. Pelseneer et Ph. Dautzenberg ').
Scaphopoda, M'lo M. Boissevain.
Cephalopoda, L. J o u b i n.
Tunicata, C. Ph. Sluiter et J. E. W. Ihle.
Pisce3, Max Web er.
Cetacea, Max Weber.
Liste des algues, Mm» A. Weber ').
Halimeda, MUe E. S. Barton. (Mme E. S. Gepp).
Corallinaceae, Mme A. Weber et M. F os 1 ie.
Codiaceae, A. et Mme E. S. Gepp.
Dinoflagellata. Coccosphacridae, J. P. LotBy.
Diatomaceae, J. P. Lotsy.
Deposita marina, O. B. Böggild.
Résultats géologiques, A. Wichmann.

Siboga-Expeditie

THE

OF THE SIBOGA

BY

H. J. HANSEN

Gjentofte (near Copenhagen)
With 5 plates and 14 text figures

Monographe XXXVIII of:

UITKOMSTEN OP ZOOLOGISCH,
BOTANISCH, OCEANOGRAPHISGH EN GEOLOGISGH GEBIED

verzameld in Nederlandsch Oost-Indië 1899 — 1900

aan boord H. M. Siboga onder commando van
Luitenant ter zee ie ld. G. F. TYDEMAN

UITGEGEVEN DOOR

Dr. MAX WEBER

Prof. in Amsterdam, Leider der Expeditie

(met medewerking van de Maatschappij ter bevordering van het Natuurkundig
Onderzoek der Nededandsche Koloniën)

BOEKHANDEL EN DRUKKERIJ

YOO&liEEK

E. J. BRILL

LEIDEN

Publié Juin 1919

* Les numéros avec un astérique ont déja paru; ceux marqués 1) seulement en partie

Déia oaru: Prix:

** * Souscription Monographies

a 1'ouvrage complet séparées

ie Livr. (Monogr.XLIV) C. Ph. Sluiter. Die Holothurien der Siboga-Expedition. Mit ioTafeln. ƒ 6. — / 7.50

2e Livr. (Monogr. LX) E. S. Barton. The genus Halimeda. With 4 plates „ 1.80 „ 2.40

3e Livr. (Monogr. I) Max Weber. Introduction et description de 1'expédition. Avec Liste des

Stations et 2 cartes B 6.75 „ 9.—

4e Livr. (Monogr. II) G. F. Tydeman. Description of the ship and appliances used for scientific

exploration. With 3 plates and illustrations „ 2. — „ 2.50

5e Livr. (Monogr. XLVII) H. F. Nierstrasz. The Solenogastres of the Siboga-Exp. With 6 plates. „ 3.90 „ 4.90
6e Livr. (Monogr. XIII) J. Versluys. Die Gorgoniden der Siboga-Expedition.

I. Die Chrysogorgiidae. Mit 170 Figuren im Text „ 3. — B 3.75

7e Livr. (Monogr. XVI a) A. Alcock. Report on the Deep-Sea Madreporaria of the Siboga-
Expedition. With s plates B 4.60 „ 5.75

8e Livr. (Monogr. XXV) C. Ph. Sluiter. Die Sipunculiden und.Echiuriden der Siboga-Exp.

Mit 4 Tafeln und 3 Figuren im Text. ... "....„ 3. — „ 3.75

9e Livr. (Monogr. Vla) G. C. J. Vosmaer and J. H. Vemhout. The Porifera of the Siboga-
Expedition. I. The genus Placospongia. With 5 plates B 2.40 „ 3. —

ioe Livr. (Monogr. XI) Otto Maas. Die Scyphomedusen der Siboga-Expedition. Mit 12 Tafeln. „ 7.50 „ 9.50
ne Livr. (Monogr. XII) Fanny Moser. Die Ctenophören der Siboga-Expedition. Mit 4 Tafeln. „ 2.80 „ 3.50
12e Livr. (Monogr. XXXIV) P. Mayer. Die Caprellidae der Siboga-Expedition. Mit 10 Tafeln. „ 7.80 „ 9.75
13e Livr. (Monogr. III) G. F. Tydeman. Hydrographic results of the Siboga-Expedition. With

24 charts and plans and 3 charts of depths B 9. — B n.25

14e Livr. (Monogr. XLIII) J. C. H. deMeijere. Die Echinoidea der Siboga-Exp. Mit 23 Tafeln. „ 15.— „ 18.75
15e Livr. (Monogr. XLVtf) René Koehler. Ophiures de 1'Expédition du Siboga.

ie Partie. Ophiures de Mer profonde. Avec 36 Planches B 16.50 „ 20.50

16e Livr. (Monogr. Lil) J. J. Tesch. The Thecosomata and Gymnosomata of the Siboga-
Expedition. With 6 plates B 3.75 B 4.70

17e Livr. (Monogr. LVI«) C. Ph. Sluiter. Die Tunicaten der Siboga-Expedition.

I. Abteilung. Die socialen und holosomen Ascidien. Mit 15 Tafeln „ 6.75 „ 9.

18e Livr. (Monogr. LXI) A. Weber— van Bosse and M. Foslie. The Corallinaceae of the Siboga-
Expedition. With 16 plates and 34 textfigures B 12.50 „ 15.50

19e Livr. (Monogr. VIII) Sydney J. Hickson and Helen M. England. The Stylasterina of

the Siboga Expedition. With 3 plates B 1.50 „ 1.90

20e Livr. (Monogr. XLVIII) H. F. Nierstrasz. Die Chitonen der Siboga-Exp. Mit 8 Tafeln. „ 5. — „ 6.25
21e Livr. (Monogr. XLV£) René Koehler. Ophiures de 1'Expédition du Siboga.

2e Partie. Ophiures littorales. Avec 18 Planches B 10.25 » I2-75

22e Livr. (Monogr. XXVIto) Sidney F. Harmer. The Pterobranchia of the Siboga-Expedition,

with an account of other species.. With 14 plates and 2 text-figures B 6.75 „ 9. —

23e Livr. (Monogr. XXXVI) W. T. Calman. The Cumacea of the Siboga Expedition. With

2 plates and 4 text-figures B 1.80 „ 2.40

24e Livr. (Monogr. LVI«) C. Ph. Sluiter. Die Tunicaten der Siboga-Expedition.

Supplement zu der I. Abteilung. Die socialen und holosomen Ascidien. Mit 1 Tafel. „ — .75 „ 1. —
25e Livr. (Monogr. L) Rud. Bergh. Die Opisthobranchiata der Siboga-Exped. Mit 20 Tafeln. „ 11.25 » i4-!o
26e Livr. (Monogr. X) Otto Maas. Die Craspedoten Medusen der Siboga-Exp. Mit 14 Tafeln. „ 9.25 „ 12.50
27e Livr. (Monogr. XIII a) J. Versluys. Die Gorgoniden der Siboga-Expedition.

II. Die Primnoidae. Mit 10 Tafeln, 178 Figuren im Text und einer Karte. . . „ 12.50 „ 16.75
28e Livr. (Monogr. XXI) G. Herbert Fowler. The Chaetognatha of the Siboga Expedition.

With 3 plates and 6 charts B 4.20 „ 5.25

29e Livr. (Monogr. LI) J. J. Tesch. Die Heteropoden der Siboga-Expedition. Mit 14 Tafeln. „ 6.75 „ 9. —
30e Livr. (Monogr. XXX) G. W. Muller. Die Ostracoden der Siboga-Exped. Mit 9 Tafeln. „ 3.50 „ 4.40
31e Livr. (Monogr. lVóis) Franz Eilhard Schulze. Die Xenophyophoren der Siboga-Exped.

Mit 3 Tafeln B 2.40 „ 3.—

32e Livr. (Monogr. LIV) Maria Boissevain. The Scaphopoda of the Siboga Expedition.

With 6 plates and 39 textfigures B 4.80 „ 6. —

33e Livr. (Monogr. XXVI) J. W. Spengel. Studiën über die Enteropneusten der Siboga-Exp.

Mit 17 Tafeln und 20 Figuren im Text B 14. — B 17.50

34e Livr. (Monogr. XX) H. F. Nierstrasz. Die Nematomorpha der Siboga-Exp. Mit 3 Tafeln. „ 2.80 „ 3.50
35e Livr. (Monogr. XIII*;) Sydney J. Hickson und J. Versluys. Die Alcyoniden der Siboga-
Exped. I. Coralliidse, II. Pseudocladochonus Hicksoni. Mit 3 Tafeln und 16 Figuren im Text. „ 2.20 „ 2.75
36e Livr. (Monogr. XXXI«) P. P. C. Hoek. The Cirripedia of the Siboga Expedition.

A. Cirripedia pedunculata. With 10 plates B 5.40 B 6.75

37e Livr. (Monogr. XLlla) L. DÖderlein. Die gestielten Crinoiden der Siboga-Expedition. Mit

23 Tafeln und 12 Figuren im Text B 8. — „ 10. —

38e Livr. (Monogr. IX) Albertine D. Lens and Thea Van Riemsdijk. The Siphonophores

of the Siboga Expedition. With 24 plates and 52 textfigures „ 13.50 „ 16.75

39e Livr. (Monogr. XLIX'rt) M. M. Schepman. The Prosobranchia of the Siboga Expedition.
Part I. Rhipidoglossa and Docoglossa, with an Appendix by Prof. R. Bergh.

With 9 plates and 3 textfigures B 4.80 ,, 6. —

40e Livr. (Monogr. XL) J. C. C. Loman. Die Pantopoden der Siboga-Expedition. Mit 15

Tafeln und 4 Figuren im Text B 6.25 „ 7.80

,41e Livr. (Monogr. LVIc) J. E. W. Ihle. Die Appendicularien der Siboga-Expedition. Mit 4

Tafeln und 10 Figuren im Text „ 4.80 „ 6. —

42e Livr. (Monogr. XLIX2) M. M. Schepman und H. F. Nierstrasz. Parasitische Proso-

branchier der Siboga-Expedition. Mit 2 Tafeln „ 1.20 „ 1.50

Prix:

Sonscription Monographïes
a 1'ouvrage complet séparées

43e Livr. (Monogr. XLIX'ó) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

Part II. Taenioglossa and Ptenoglossa. With 7 plates ƒ

44e Livr. (Monogr. XXIXa) Andrew Scott. The Copepoda of the Siboga Expedition.

Part I. Free-swimming, Littoral and Semi-parasitic Copepoda. With 69 plates. .
45e Livr. (Monogr. LVlb) C. Ph. Sluiter. Die Tunicaten der Siboga-Expedition.

II. Abteilung. Die Merosomen Ascidién. Mit 8 Tafeln und 2 Figuren im Text.
46e Livr. (Monogr. XLIX'c) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

Part III. Gymnoglossa. With 1 plate „ — .80

47e Livr. (Monogr. XIII b) C. C. Nutting. The Gorgonacea of the Siboga Expedition.

III. The Muriceidse. With 22 plates

48e Livr. (Monogr. XIII3') C. C. Nutting. The Gorgonacea of the Siboga Expedition.

IV. The Plexauridse. With 4 plates

49e Livr. (Monogr. L.Vld) J. E. W. Ihle. Die Thaiiaceen (einschliesslich Pyrosomen) der

Siboga-Expedition. Mit 1 Tafel und 6 Figuren im Text

oe Livr. (Monogr. XIII32) C. C. Nutting. The Gorgonacea of the Siboga Expedition.

V. The Isidas. With 6 plates

ie Livr. (Monogr. XXXVII) H. J. Hansen. The Schizopoda of the Siboga Expedition. With

16 plates and 3 text figures

2e Livr. (Monogr. XIII P) C. C. Nutting. The Gorgonacea of the Siboga Expedition.

VI. The Gorgonellidae. With 1 1 plates

3e Livr. (Monogr. XV a) J. Playfair Mc Murrich. The Actiniaria of the Siboga Expedition.

Part I. Ceriantharia. With 1 plate and 14 text figures

4e Livr. (Monogr. XIII£4) C. C. Nutting. The Gorgonacea of the Siboga Expedition.

VII. The Gorgonidse. With 3 plates

5e Livr. (Monogr. XXXIX a) J. G. de Man. The Decapoda of the Siboga Expedition.

Part I. Family Penaeidae

6e Livr. (Monogr. LXII) A. & E. S. Gepp. The Codiaceae of the Siboga Expedition including

a Monograph of Flabellarieae and Udoteae. With 22 plates .

7e Livr. (Monogr. Xlllb5 C. C. Nutting. The Gorgonacea of the Siboga Expedition.

VIII. The Scleraxonia. With 12 plates

8e Livr. (Monogr. XLIX'd) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

Part IV. Rachiglossa. With 7 plates

9e Livr. (Monogr. Vla') G. C. J. Vosmaer. The Porifera of the Siboga-Expedition.

II. The genus Spirastrella. With 14 plates

6oe Livr. (Monogr. XXXIX a') J. G. de Man. The Decapoda of the Siboga Expedition.

Part II. Family Alpheidae

61e Livr. (Monogr. LUIa) Paul Pelseneer. Les Lamellibranches de 1'Expédition du Siboga.

Partie Anatomique. Avec 26 planches .

62e Livr. (Monogr. XXIV' a) R. Horst. Polychaeta errantia of the Siboga Expedition.

Part I. Amphinomidae. With 10 plates

63e Livr. (Monogr. LUIb) Ph. Dautzenberg et A. Bavay. Les Lamellibranches de 1'Expéd.

du Siboga. Partie Systématique. I. Pectinidés. Avec 2 planches .

64e Livr. (Monogr. XLIX1,?) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

Part V. Toxoglossa. With 6 plates and 1 textfigure

65e Livr. (Monogr. LVII) Max Weber. Die Fische der Siboga-Expedition. Mit 12 Tafeln und

123 Figuren im Text

66e Livr. (Monogr. XLIX/) M. M. Schepman. The Prosobranchia, Pulmonata and Opistho-
branchia Tectibranchiata Tribe Bullomorpha of the Siboga Expedition.

Part VI. Pulmonata and Opisthobranchia Tectibranchiata Tribe Bullomorpha. With

2 plates „ 1.75 „ 2.20

6je Livr. (Monogr. XXXI b) P. P. C. Hoek. The Cirripedia of the Siboga-Expedition.

B. Cirripedia sessilia. With 17 plates and 2 textfigures „ 8. — „ 10. —

68e Livr. (Monogr. LlXa) A. Weber-van Bosse. Liste des Algues du Siboga.

I. Myxophyceae, Chlorophyceae, Phaeophyceae avec Ie concours de M. Th. Reinbold.

Avec 5 planches et 52 figures dans Ie texte

69e Livr. (Monogr. XXXIXa) J. G. de Man. The Decapoda of the Siboga Expedition.

Supplement to Part I. Family Penaeidae. Explanation of Plates

70e Livr. (Monogr. Vila) A. Billard. Les Hydroïdes de 1 Expedition du Siboga.

I. Plumularidae. Avec 6 planches et 96 figures dans Ie texte

71e Livr. (Monogr. XXXIX/>) J. E. W. Ihle. Die Decapoda brachyura der Siboga-Expedition.

I. Dromiacea. Mit 4 Tafeln und 38 Figuren im Text

72e Livr. (Monogr. XXXII a) H. F. NierstraSZ. Die Isopoden der Siboga-Expedition.

I. Isopoda chelifera. Mit 3 Tafeln

73e Livr. (Monogr. XVII) A. J. van Pesch. The Antipatharia of the Siboga Expedition. With

8 plates and 262 textfigures

74e Livr. (Monogr. XXXIXa') J. G. de Man. The Decapoda of the Siboga Expedition.

Supplement to Part II. Family Alpheidae. Explanation of Plates

75e Livr. (Monogr. XXVIIIa) Sidney F. Harmer. The Polyzoa of the Siboga Expedition.

Part I. Entoprocta, Ctenostomata and Cyclostomata. With 12 plates

76^ Livr. (Monogr. XXXIXa2) J. G. de Man. The Decapoda of the Siboga Expedition.

Part III. Families Eryonidae, Palinuridae, Scyllaridae and Nephropsidae. With

4 plates „ 3.75 „ 4-75

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Prix :

Souscription Monographies
a l'ouvrage complet séparées

77e Livr. (Monogr. XIV) Sydney J. Hickson. The Pennatulacea of the Siboga Expedition,

with a general survey of the order. With 10 plates, 45 text figures and 1 chart .... ƒ10.75 / 13.50
78e Livr. (Monogr. XXXIX£') J. E. W. Ihle. Die Decapoda brachyura der Siboga-Expedition.

II. Oxystomata, Dorippidae. Mit 39 Figuren im Text. : „ 1.90 „ 2.40

79e Livr. (Moncgr. LXV) O. B. BÖggild. Meeresgrundproben der Siboga-Expedition. Mit

1 Tafel und 1 Karte „ 2.25 „ 3. —

8oe Livr. (Monogr. XXIVó) R. Horst. Polychaeta errantia of the Siboga Expedition.

Part II. Aphroditidae and Chrysopetalidae. With 19 plates and 5 textfigures . . . . „ 7.75 „ 9.75
8 1« Livr. (Monogr. XLVIö) L. Döderlein. Die Asteriden der Siboga-Expedition.

I. Die Gattung Astropecten und ihre Stammesgeschichte. Mit 17 Tafeln und 20 Figuren

im Text „ 8.75 „ 11.—

82e Livr. (Monogr. XXXIX c) J. J. Tesch. The Decapoda brachyura of the Siboga Expedition.

I. Hymenosomidae, Retroplumidae, Ocypodidae, Grapsidae and Gecarcinidae. With 6 plates. „ 5.. — „ 6.25
83e (Monogr. XLII^) Austin H. Clark. The unstalked Crinoids of the Siboga Expedition.

With 28 plates and 17 textfigures „ 16. — „ 20. —

84e Livr. (Monogr. XXXIXc1) J. J. Tesch. The Decapoda brachyura of the Siboga Expedition.

II. Goneplacidae and Pinnotheridae. With 12 plates „ 6.75 „ 9. —

85e Livr. (Monogr. XXXIX ö2) J. E. W. Ihle. Die Decapoda brachyura der Siboga-Expedition.

III. Oxystomata: Calappidae, Leucosiidae, Raninidae. Mit 71 Figuren im Text. . . . „ 5.60 „ 7. —
86e Livr. (Monogr. XXXVIII) H. J. Hansen. The Sergestidae of the Siboga Expedition. With

5 plates and 14 text figures. „ 4.50 „ 6. —

Voor de uitgave van de resultaten der Siboga-Expeditie hebben bijdragen
beschikbaar gesteld:

De Maatschappij ter bevordering van het Natuurkundig Onderzoek der Nederlandsche Koloniën.

Het Ministerie van Koloniën.

Het Ministerie van Binnenlandsche Zaken.

Het Koninklijk Zoologisch Genootschap » Natura Artis Magistra" te Amsterdam.

De >Oostersche Handel en Reederij" te Amsterdam.

De Heer B. H. de Waal, Oud-Consul-Generaal der Nederlanden te Kaapstad.

M. B. te Amsterdam.

The Elizabeth Thompson Science Fund.

Dr. J. G. de M. te Ierseke.

CONDITIONS GÉNÉRALES DE VENTE.

i°. L'ouvrage du „Siboga" se composera d'une série de monographies.
2°. Ces monographies paraitront au fur et a mesure qu'elles seront prêtes.

30. Le prix de chaque monographie sera différent, mais nous avons adopté comme base générale du prix de
vente: pour une feuille d'impression sans fig. flor. 0.15; pour une feuille avec fig. flor. 0.20 a 0.25;
pour une planche noire flor. 0.25; pour une planche coloriée flor. 0.40 ; pour une photogravure flor. 0.60.

4°. Il y aura deux modes de souscription

a. La souscription a l'ouvrage complet.

b. La souscription a des monographies séparées en nombre restreint.
Dans ce dernier cas, le prix des monographies sera majoré de 25 %•

5°. L'ouvrage sera réuni en volumes avec titres et index. Les souscripteurs a l'ouvrage complet recevront
ces titres et index, au fur et a mesure que chaque volume sera complet.

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