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THE GORGONACEA OF THE SIBOGA EXPEDITION

IV. THE PLEXAURID^E

Sib o ga- Expeditie

XIII b'

THE

GORGONACEA OF THE SIBOGA EXPEDITION

IV. THE PLEXAURID^

BY

C C NUTTING

Professor of Zoology, State University of Iowa

With 4 plates

(Aided by a grant from the ELIZABETH THOMPSON SCIENCE FUND)

late E. J. BRILL

PUBLISHERS AND PRINTERS

LEYDEN — igio

THE GORGONACEA OF THE SIBOGA EXPEDITION

IV. THE PLEXAURIDyE

BY

C. C. NUTTING,

Professor of Zoology, State L'nivevsity of Iowa.

With 4 plates.

(Aided by a grant from the elizabeth thompson science fund.)

Family Plexaurid.e Gray.

Plexaura Lamouroux. Exposition Méthodique, 182 1, p. 35.

Plexauridcc Gray. Annals and Magazine of Natural History, Series 3, Vol. IV, 1859.

Eunicea -\- Plexaura Milne Edwards et Haime. Histoire naturelle des Coralliaires, 1857, Vol. I,

pp. 146, 152.
Euniceidtc Kólliker. Icones Histologie^, II, 1865, p. 137.

Plexauridcc Verrill. Transactions Connecticut Academy of Science, Vol. I, 1869, p. 135.
Euniceidcc Ridley. Annals and Magazine of Natural History, Series 5, Vol. n, 1883, p. 253.
Plexauridcc Wright and Studer. Challenger Reports, the Alcyonaria, 18S9, p. 135.
Plexauridcc Studer. Alcyonarien aus der Sammlung des Naturhistorischen Museums in Lübeck,

1894, p. iii.
Plexauridcc Brundin. Bihang til Svenska Vet.-Akad. Handlingar, Band 22, Afd., 17, N° 3,

1896, p. 17.
Plexauridcc Thomson and Henderson. Ceylon Pearl Oyster Report, Alcyonaria, 1905, p. 304.

The original definition of the family, as given by Gray, is as follows:
"Bark granular, persistent, cork-like, without any important grooves. Cells placed equally
on all sides of the branches".

S1BOGA-EXPEDITIE XIII i'. I

7

\ usual, was quick i«> discern the most important charai t< i by which this

family can bc differentiated from its allies. Ilis definition is as follows:

"Corallum usually dichotomous or meur or less arborescent. Axis horn-like, or more or

tlly ai base. Longitudinal ducts equal, arranged regularly all around the

nchyma usually thick. Cells scattered over all parts of the surface, flat, or elevated

on prominent \ rentacles at base, and sides of the polyps stiffened with large fusiform

spieul nenchyma usually large, of various forms, must usually these are large

i with clubs or crosses",
r the purposes of this work the following definition is otïered :

enenchyma thick, without evident grooves; axis cylinder horny, or horny and calcareous,
but ointed. Primary water-vascular canals in a regular series around the axis. Calyces

on all sides of the stem and branches, often entirely included. Spicules various, usually spindles,
clubs, butterfly-shaped or Blattkeulen.

As Wright and Studer remark: "The genera belonging to the family as it now stands,
certainl) require revision".

The material secured by the Siboga Expedition that can be referred to the Plexauridae

is uot sufficiënt in extent to justify the author of this report in undertaking a n-vision of the

family, and he therefore contents himself with recogfnizingf the eenera defmed in the Challeneer

rt, and the addilion of a single new genus which seems necessary to accommodate a

remarkable species collected by the Siboga Expedition.

The most important feature in the diagnosis of genera in this family seems to be the
character of the axis cylinder, the forms of the calyces and spicules being however, of greal
service in generic description in some cases.

The following artihcial key may be of service in aiding the student to determine the
generic affinities of species.

Artificial key to the genera of Plexauruxe.

i, branches and horny axis distinctly flattened Platygorgia) '

Calyces prominent and bilabiate (Eunicea

Calyces moderately prominent, not bilabiate.

Spicules armed with long, truncate verrucae (Anthoplexaurai

Spicules small, the outer layer club-shaped iParaplexaura

neither bilabiate nor decidedly prominent. Axis not distinctl) flattened.
Axis entirely horny, except at base, or with calcareous particles deposited
in the central core.
Spicules usually spindles. horizontally or longitudinally placed in outer
r of ccenenchyma.
nchyma thick. No very large, bar-like spicules Plexaura

in tlit.- Sibi

3

Coenenchyma thin. Large, bar-like spicules very prominent. . . . Hicksonella
Spicules of outer layer clubs or "Blattkeulen" vertically placed.

Clubs large. Terminal branches long and slender Plexauroides

Clubs small. Terminal branches short (Paraplexaura)

Clubs minute, their club-ends inflated and free (Eunicella)

Axis with a central horny core, around which is a tubular casing containing
more or less calcareous matter.

Spicules large, clubs, crosses and triradiate forms predominating. . . (Plexaurella)

Spicules small, short oval spindles and doublé spindles predominating. Euplexaura

The writer is un.ible to lïnd any character in the definition of the gemis Psammogorgia Verrill by which it can be differentiated
from others of the family. He therefore gives the definition proposed by the original describer, which is as follows :

"■Psammogorgia Verrill. Corallum dichotomous or subpinnate, wilh ronnd branches. Axis horn-like. Ccenenchyma moderately
thick, the surface finely granulated with small rough spicula. Cells scattered, sometimes flat, more frequently raised in the form of rounded
verrucje. Polyps with rather large, elongated, slender warty spindles at the bases of the tentacles. Spicula of the ccenenchyma mostly short,
thick, and very rough, warty spindles and rough, warty clubs of moderate size".

(Verrill, Transactions Connecticut Academy of Science, Vol. I, Part 2, p. 414).

Synoptic view of the genera and species of the Siboga

collection of Plexaurid.e.

*The asterisk (*) denotes a new genus or species.

Plexaura.

*P. aggregata, *P. attemeala, *P. recta, *P.
p/atystoma, *P. pinnata, 'P. fiava.

Plexauroides.
P. praelouga, P. lenzii.

Euplexaura.
*E. rubra, *E. mollis, *E. reticulata.

Hicksonella.
*H. princeps.

Psammogorgia.
P. arbuscula.

The above table indicates that of the thirteen species of the Plexauridse collected, ten
appear to be new, and nearly half of the total number belong to the type genus, Plexaura.
This genus has heretofore been unrepre.sented in the East Indian Region, with the exception
of one species which Thomson and Henderson identify as a variety, (flexuosa) of P. antipathes.
The present writer is of the opinion that this form is identical with the new species P. aggregata,
described beyond.

Systematic discussion of genera and species.
Plexaura Lamouroux (emended).

Plexaura Lamouroux. Histoire des Polypiers coralligènes flexibles, 1 8 1 6, p. 424.

Plexaura Lamouroux. Exposition Méthodique, 1S21, p. 35.

Plexaura Milne Edwards et Haime. Histoire Naturelle des Coralliaires, Vol. 1, 1857, p. 152.

ra Duchassaii tti, Coralliaires « U -, Antilles, iS6o, p. 25.

1 K^llikcr. Iconcs I listo , p. I 38.

PU Wright and Studer. (. 'hallen irts, the Alcyonaria, [889, p. 1^7.

. homson and Hcnderson. Pearl Oystei Fisheries Rcports, the Alcyonaria, 1905, p. 304.

rhe original describer, Lamouroux, gave a definition for this genus that needs little
change to fit it for modern use. h is as follows:

'Polypier dendroïde, rameux, souvent dichotome; ramaux cylindriques et roides; .1
'■inent comprimé; . dans l'étal de dessication, subéreuse, ou terreuse, très-épaisse,

int peu d'eflfervescence avec les acides, et couverte de cellules éparses, grandes, nombreuses,
/ent in< I qui ne sont jamais saillantes".

Eliminating non essential points, the difinition used for the present work will be as follows:
enenchyma thick, calyces included and distributed on all sides of the stem and branches.
Spicules in the form of warty spindles and clubs, usually in two layers. Axis enrirely horny,
at the base of the stem of large specimens.

The character of the axis will ditïerentiate this genus trom Plexaurella, which greatly
it superficially, and from Euplexaura and Pseudoplexaura. The characters of the
spicules will separate it from Plexauroides and Hicksonella.

The type of this genus is Plexaura heteropora (Lamarck).

( >wing to the superficial resemblance between Plexaura and Plexaurella, both genera
abundant in species, it is impracticable, without recourse to the types, to teil which of the
species originally described should be placed in Plexaura. Both of these genera are but sparsely
represented in previous collections from the Western Pacific, or Indo-Pacific region. Hence it is
not surprising that the species in the Siboga collection are all apparently new.

1. Plexaura aggregata new species. (Plate I, figs. 1, ia; Plate IV, fig. 1).

58. Anchorage off Seba, Savu Island. Up to 27 meters.
Stat. 65*. 70 o' S., 1200 34.5 E. Flores Sea. Depth changing rapidly from 400 — 120 meters.

( <>ral bottom.
Stat. 213. Saleyer anchorage, and surroundings. Up to 36 meters.
Stat. 258. Tual anchorage, Kei [slands. Reef. 22 meters.
Stat. 515. Anchorage Ka-t ■ >! Saihis Besar, Paternoster Islands. Up to 36 meters.

Colony consisting of a dense clump of branches, 36 cm. in height. The branches all

spring from the base <>l the colony and al most immediately begin to subdivide. The base is

about 4.5 cm. broad, and the largesl branches have a diameter of about 2 cm. The branches

divide irregularly, but ordinarily the division is not dichotomous, until ultimate branchings of

■ r iolh order are attained, the result being hundreds of terminal twigs with a diameter

mm. All of the branches are round and smooth, and distinctly enlarged at their

ends. 'I he calyces are inserted on all sides of the branches, and are evenly spaced, averaeiiiL;

•ut 1 mm. apart. TIn- ccenenchyma is very thick.

The individual calyces are completely inserted. leaving the surface of the branch perfectly

re pitted by the calyx apertures. These pits are quite small, in alcoholic

pits being oval instead of round, their greater diameter being parallel to the

long axis of the branch and seldom attaining a length of over i mm. The margin appears to
be divided into shallow lobes lying horizontally. The polyps are small, with delicate fringed
tentacles, their bodies bearing eight longitudinal bands of very slender spindles. The tentacles
appear to be unarmed.

A cross section of a branch shows a horny axis surrounded by very large watervascular
canals symmetrically arranged on all sides of the axis, their cavities being larger than those
of the calyces.

S p i c u 1 e s. These are all very small and the prevalent type is a very deeply tuberculate
spindle with the tubercles arranged in definite series or zones. Clubs are also common. There
are no well-defined layers of spicules in the ccenenchyma.

Color. The colony is very light brown, in alcohol. The axis is almost black proximally,
and lightens distally. It has a slender, white core, which is not calcareous.

This species is probably identical with Plexaura antipathes var. flexuosa Thomson and
Henderson. Ceylon Pearl Oyster Fisheries Report, the Alcyonaria, 1895, p. 305.

It seems a very distinct species, however, differing from Plexaura antipathes in having
no violet spicules.

A specimen from Stat. 258 is much larger than the one described, being 90 cm. in
height, with a main stem 2 cm. in diameter. At the base there is a solid, flinty, calcareous
layer surrounding a horny core 7 mm. in diameter. The axis of the branches is entirely horny.

2. Plexaura attenuata new species. (Plate I, figs. 2, ia\ Plate IV, fig. 2).

Stat. 162. Between Loslos and Broken Islands, West coast of Salawatti. 18 meters.
Stat. 164. i°42'.5 S., i30°47'.sE. Near New Guinea. 32 meters.
Stat. 285. 8°39'.iS., 1270 4.4 E. Timor Sea. 34 meters.
"Bay of Batavia. Professor SLUITER leg.".

Specimen (incomplete) consisting of a straight, wand-like stem about 37 cm. long, from
which project three short, straight branches all of which have their distal ends broken off. The
greatest diameter of the main stem is 3 mm., tapering to 2 mm. near its distal end. The
calyces are evenly distributed on all sides of the colony, but are larger and further apart than
in Plexaura aggregata. Nearly all of the polyps are partly extended, and this gives the calyces
the appearance of being partly exserted and verruciform. In fact, however, the calyces are
hardly raised above the general level of the ccenenchyma when the polyps are retracted,
although there may even then be a slight swelling.

The individual calyces are about 1.7 mm. in diameter, and when the polyp is retracted
the calicular margin shows eight very plain scallops or lobes which are larger and deeper than
in the preceding species. The polyps are able to protrude their bodies considerable above the
calyces and still keep the tentacles folded within the body walls, where they form an acorn-
shaped mass, the individual tentacles being plainly seen within the transparent body wall. The
lower part of the polyp shows very delicate longitudinal bands of spicules.

A crus-. if the stem shows .1 thick coenenchyma in which the calyces are sunken

almost t<» the axis cylind< lals are not nearly so regular and distincl as in PUicaura

| n\. with a white noncalcareous centre.

Spicul» spicules are all smal], terete spindles with regularly disposed annular

[iving a very symmetrical pattern. Definite layers of spicules can
not be made 1 ut, .1- the) seem i<> pack the coenenchyma from the surface nearly to the axis.
rhe spi those which Kent figures as characteristic of the genus Verrucella in the

Monthly M pical Journal, Feb. 1 '. is7". Plate XI. Il, fig. 3.

rhe specimen is a light brown or tan color. The axis is dark brown and the

3. Plexaura recta new species Plate 11, figs. 3, 3a; Plate I\'. fig. 3).

Stat. 273. Anchorage off Pulu Jedan, E. coast of Am [slands I V ai 1 Banks). 13 meters.
Stat Buka or Cyrus Bay, South coast of Rotti Island. 34 metei .

Pulu Missa near Flores. J. II. DE SlSO don. 3 specimens.

1 olony flabellate in form, not reticulate, attaining a height of 59 cm. About 2 cm. above
the base the main stem divides into two, and each of these divides often, but not usually, in a
dichotomous manner until twigs of the 7,h order of division are attained. The nltimate branches
are long and slender, erect and parallel. They sometimes attain a length of 39 cm., are round,
and of approximately of the same diameter throughout. The main stem is 1 cm. in diameter
at its base, and the ultimate branches are from 2 to 3.5 mm. in diameter. The calyces are
evenly distributed on all sides and are entirely included when the polyps are retracted, leavin^
but a slightly elevated horder around the apertures. The apertures, in dried specimens, form
sharp oval openings.

The individual calyces are smal! and sunken almost to the axis. The margin is surrounded
by well-marked scallops as in the preceding species. The tentacles in the specimen desa
often protrude through these a])ertures, although the polyps themselves are entirely retracted.
The tentacles are very long, with long delicate fringes. I am unable to find any spicules in
the body walls or tentacles.

A cro tion oi a branch reveals a condition much as in the last species. The axis

is noncalcareous. with a white centre around which are a number of light-colored strands, none
of which are calcareous. The canals are proportionally small and inconspicuous, and their
arrangement can not easily be determined.

Spicules. These are ver)' short, stout, small densely tuberculate spindles, often so short
almost globular. The tubercles are so closely crowded as to cover the whole surface
almost like the round cells ot a morula. There is no division of spicules into definite layers.
dor. The colony is dark brown, in alcohol. Axis black, lightening distally. A specimen
- ■ ; is '■( cm. in height, and more profusely branched than the type described.

7

4. Plcxaura filatystoma new species. (Plate II, figs. 2, 20; Plate IV, fig. 4).

Stat. 43. Anchorage off Pulu Sarassa, Postillon Islands. Up to 36 meters.

Colony of irregular and straggling habit, 16 cm. in height. The main stem gives off
four branches of very unequal size, one of which arises about 5 cm. from the base. This
becomes the main part of the colony, bearing several short stubby branches very unequally
distributed, and one large descending branch producing a number of slender undivided branchlets
in art indistinctly pinnate manner. The diameter of the main stem and largest branch is 1.8 mm.
The calyces are entirely included and rather sparsely distributed on all sides of the stem and
branches. The polyps in retraction draw the calyx margins together so that the apertures are
almost obliterated. In the dried fragment of a branch, however, the apertures are really much
larger than in either of the preceding species.

The individual calyces, although hardly evident externally, are really considerably broader
than in the other species described. The apertures are oval, the long diameter being parallel
with the axis. The longer diameter of the calyx is about 1.5 mm. The polyps have eight
longitudinal bands of slender spindles, and the tentacles have a number of delicate spindles on
their dorsal surface. These latter are arranged in two longitudinal series on each tentacle, so
as to approach the en chevron arrangement on the proximal portions. The layers of the ccenen-
chyma are not well defined.

A cross section of a branch shows a moderately thick ccenenchyma, well-defined but not
numerous watervascular canals, and a horny axis with a white, noncalcareous core.

S p i c u 1 e s. These are rather slender, usually curved spindles of the same general type
as in Plcxaiira attenuata, but larger than any others thus far described in this report, some
of them attaining a length of 1 mm. The annular arrangement of the tubercles is not so well-
markecl as in P. attcnuata.

Color. Very pale gray, almost white, in alcohol. The axis is golden brown proximally
and very pale distally.

5. Plexaura pinnata new species. (Plate I, figs. 3, 3a; Plate IV, fig. 5).

(The locality can not be given, as the label is missing).

Colony flabellate in form, 16 cm. in height and with a spread of 9 cm. The main stem
has been broken just above the origin of the first main branch, which thus constitutes practically
the entire specimen. This branch bears numerous branchlets in a pinnate manner, but they are
neither opposite nor regularly alternate. The calyces are regularly distributed on all sides of
the stem and branches, and are about 1 mm. apart.

The individual calyces are included, there being 110 external swelling except a slight
tumidity about the margin, as in other species of this genus. The aperture is quite small, usually
round, the tentacles beino- sunken below the eight-lobed fringe around the inner side of the margin.
The polyp is much compressed, when retracted, a longitudinal section being an oval whose width
is greater than the length. There are a few delicate spindles in the polyp body and tentacles.

A cross section of the stem shows a moderately thick coenenchyma, a series of smal! but
well-defined watervascular canals, and an axis with a proportionally large white central core.

Spicules. rhese are all small, but of several types. Regular, ten-te spindles with
nilarly disposed, very prominent verrucae are common. There are also many doublé clubs
such ;b 1\ tlls "laminatoclavate" spicules1, with a marked constriction around the middle.

A number <>( crosses an- also found, the arms of the crosses being tumid and densely
tuberculate, forming a four-leaved rosette. While the coenenchyma is divided into two layers
by the watervascular system, 1 tan not determine any constant difference between the spicules
of these laj

r. The colony in alcohol is very light buffy brown. The axis is dark brown and
spicules colorless.

o. Plexaura flava new species. (Plate II, figs. i, \a-, Plate IV, fig. 6).

St.it. ui. Bay of Labuan Trini;. West coast of Lombok. iS — 27 meters.

Stat. 60. Haingsisi, Samau Island, Timor. Reef. 23 meters.

Stat. 142. Anchorage off Laiwui, coast of Obi Major. 23 meters.

Stat. 2y$. Anchorage off Pulu Jedan, Kast coast of Aru Islamls. 13 meters.

A number of fragments of apparently more than one specimen were collected at Station 19.
The largest consists of a dense tuft of branches and branchlets. and is 37 cm. long. The main
stem is S mm. in diameter, and abruptly angulated 2.2 cm. from its base. After giving off
one compound, and a number of simple branches, it divides into two approximately equal parts
12.5 cm. from its base. These branches give off numerous compound and simple branchlets. On
their proximal portions both the main branches and their compound offshoots give off terminal
twigs from all sides. On their (listal portions they give off usually simple twigs with a strong
tendency to a regularly pinnate arrangement, although occasional twigs are given off from both
the front and back of the distal parts of the colony. The pinnae are about 4 mm. apart, on
the average, and about 1.5 mm. in diameter. The main stem is rlattened, but the branches
are round. The calyces are rather more prominent than in most species of this genus, and are
distributed on all sides of the branches, with a tendency to be more crowded on the sides
than on the front and back.

The individual calyces show externally as very low verrucae. The aperture is often

mpletely closed by the contraction of the calyx margin. The polyps are completely retractile,

but the tentacles do not sink below the level of the polyp walls. Thus there appears no Iobular

margin around th<: calycular mouth, but the tentacles, in retraction, lie immediately below the

margin. The tentacles are very deeply fringed. There are a few very minute, bar-like spicules

the body walls and basal parts of the tentacles.

A section of a branch shows a rather ill defined series of watervascular canals,

is wholly corneous with a rather large central core which is white.

f the I Monlhly Microscopical Journal, Feb. 1, 1870, p. 76, plate XI. II. figs. 38, 43.

Spie ui es. The spicules are mainly spindles, straight and curved, relatively large as
compared with most of the others in the Siboga collection of this genus, but not so as compared
with some other Plexauridae. A few club-shaped forms are present.

Color. The colony is a light naples yellow, probably brighter when fresh. The axis is
brown and the spicules colorless.

This species differs in general appearance from the other species of Plexatcra in the
collection, but the writer is unable to find any structural difference, unless it be in the spicules,
which do not seem of a sufficiently different type to warrant its exclusion from the genus.

Plexauroides Wright and Studer (emended).

Plexauroides Wright and Studer. Challenger Reports, the Alcyonaria, 1889, p. 138.
Plexauroides Studer. Alcyonarien aus der Sammlung des Naturhistorischen Museums in Lübeck,

1894, p. in.
Plexauroides Brundin. Alcyonarien des zool. Museums in Upsala, 1896, p. 19.
Plexauroides Kükenthal. Japanische Gorgoniden, II. Teil, 1909, p. 27.

The orieinal definition of this o-enus is as follows :

"Colony branching, mostly in the one plane. Stem and branches cylindrical. Axis horny
dense, with the central portion calcareous. Nutriënt canals symmetrically arranged. Ccenenchyma
thin, consisting of two very distinct layers of spicules, the one nearest the axis is composed of
irregular stellate forms, the outer layer of large Blattkeule, the broad foliar expansions of which
project beyond the surface of the ccenenchyma forming a rough imbricated surface".

The polyps are numerous, fully retractile, with scarcely visible verrucae, the edges of
these latter being fringed with rows of the broad projecting folia of the Blattkeule.

Kükenthal re-defines the genus so as to exclude Plexauroides verrucosa Brundin, and
P . asper Moroff, which he places in a new genus Paraplcxaura, which he differentiates from
Plexauroides mainly on account of short terminal branches and true calyces.

Aside from the original definition, there Is no reference to the calcareous core to the
axis, and it is not referred to by Brundin in his discussion of the genus. The specimens in the
Siboga collection do ïot show this character, but there is a white core to the axis which is
not calcareous. It may possible have deceived the describer of the genus, as it looks very
much like a calcareous core.

The spicules are the characteristic feature of the genus, which may be described as follows :

Plexauridae with a horny axis, long terminal branchlets inserted calyces, ccenenchyma
rather thin, but composed of two very distinct layers of spicules. The outer layer is formed of
spicules whose proximal part bears branched, warty radiating processes projecting downward
and outward ; and whose distal portions are composed of broad, leaf-like expansions standing at
right angles to the surface of the branch when in situ. The inner layer of spicules is composed
of smaller cruciform or stellate forms.

The type of this genus is Plexauroides prerlonga (Ridley). The other known species are
P lexatiroides indica Ridley, P. unilateralis Studer, P. lenzii Studer, P. michelsoni Kükth.,
P. rigida Kükth., P. simplex Kükth. and P. filiformis Kükth.

SIBOGA-EXPEDIT1E XIII /''.

ÏO

This genus lias much in common with the genus Eunicella Verrill, especially in the
form of the spiculi

i . PUxauroides / Ridl< j

on the Zoological Collections of H. M. S. Alert, 1884,9.339.
it and Studer. Challenger Reports, the Alcyonaria, 1889, p. 13S.
var. elongata Thomson and Henderson. Ceylon Pearl Oyster Fisheries
. .ui.i. [905, p. 305.

Stal Vnchorage off Pulu Jedan, East coast of Aru [slands. (Pearl Banks). [3 meters.

Iried) flabellate in form, 62 cm. in height and about 20 cm. in spread. The
main stem gives off .1 large branch 9 cm. from its base, and this bears several lateral branches
which are usually simple and attain a length of as much as 24 cm. The remainder of the
\ consists of the continuation of the main stem and its branches. These latter are roughly
alternate in position and tend to divide dichotomously until branches of the third order are
produced. The terminal twigs are very long and slender. The diameter of the main stem
mm., and of the branches about 3 mm. The calyces are entirely inserted, and are so
completely immersed that only their openings are sein. They are evenly distributed on all
sides of the branches, their mouths hein»; about 1 mm. apart.

Nothing hut the openings of the individual calyces are to be seen in the dried specimens.
These are oval and less than 1 mm. in their longer diameter. The polyps could not be seen
in the specimens at hand.

A cross section of a branch shows a very thick ccenenchyma with a superficial layer of
* Blattkeulen" standing at right angles to the surface, and an inner layer of colorless cruciform
or stellate spicules. The watervascular canals are large and conspicuous. The axis cylinder has
a white, noncalcareous core.

Spicules. These are mainly typical "Blattkeulen" with a branched and densely tuber-
culate basal portion and a distal, disk-like comparatively smooth part. This latter portion is
often inflated in appearance and approaches very closely the Echinogorgia type, as pointed out

der in his study of Plexauroides lenzii^ besides these, which are by far the most
numerous, there are cruciform and stellate spicules of much smaller size.

C o 1 o r. The colony is bright crimson. The axis is black, fading distally to a light
enish brown. The spicules are bright red.

General distribu tion. The type was secured in Torres Strait. The Challenger found
it ofl Cape Vork at a depth of 8 fathoms. It was secured also from the Pearl Banks of Ceylon.

'1 his is a very beautiful and well marked species.

2. Plexauroides lenzii Studer.

Plexauroides lenzii Studer. Alcyonarien aus der Sammlung des Naturh. Museums in Lubeck.
14, p. 114.

Naturh. Museums in LUbeck, 1894. p. 114.

1 1

Stat. 258. Tual Anchorage, Kei Islands. 22 meters. Lithothamnion.

Stat. 273. Anchorage off Pulu Jedan. East coast of Aru Islands. (Pearl Bank). 13 meters.

Colony flabellate in form, 21 cm. in height and about 16 cm. in diameter. The main
stem forks about 2.5 cm. from its base, and one of the resulting divisions again forks, making
three main branches to the colony, which give off lateral branches in a very irregular manner,
often redividing untii branchings of the 5th and 6th orders are attained. The diameter of the
main stem is 6 mm., of the main branches 5 mm. and of the slender, straight ultimate branches
2 mm. The calyces are evenly distributed on all sides of the stem and branches, their mouths
being ordinarily about 1 mm. apart from centre to centre.

The individual calyces are included, there being nothing visible externally except a very
slight swelling around the margins, this swelling fading insensibly into the general surface of
the ccenenchyma. The calyx walls are covered with the imbricating scales or foliar expansions
of Blattkeulen that form the distal portions of the superficial layer of spicules. The polyps are
completely retractile, the calycine apertures being in most cases obliterated. The retracted polyps
are very much flattened, being really reduced to disk-shaped bodies. There are a few slender
spicules on the upper surfaces of the tentacles, there usually being two longitudinally disposed
on each tentacle.

A cross section of a branch shows the two layers of spicules characteristic of the genus,
the outer with the scarlet foliar expansions standing erect, as if radiating from the axis. The
inner layer is composed of colorless spicules which are small and of various forms. The water-
vascular canals are not well differentiated, and the axis is horny, sometimes with a hollow centre.

Spicules. The Blattkeulen are like those of the Echinogorgia type found in the Muriceidse,
but the smooth, distal foliar expansions are aggregated into a knob-like head. Sometimes this
is much flattened so as to become disk-shaped. The proximal, immersed parts of these spicules
bear dense masses of tuberculated or branched processes reaching downward and outward.
Besides these there are a number of tuberculate spindles, crosses, butterflies, clubs, etc. which
are found in the inner layer of the ccenenchyma.

Color. The colony is bright scarlet, as are the Blattkeulen.

The specimens collected by the Siboga Expedition do not show the calcareous core to
the axis cylinder described by Studer. They agree, however, so well in all other particulars
that the writer feels confident of the correctness of his identification.

Euplexaura Verrill (emended).

Eiiplexaura Verrill. Proceedings of the Essex Institute, VI, 1S69, p. 143.
Euplexaura Wright and Studer. Challenger Reports, the Alcyonaria, 1SS9, p. 143.
Euplexaura Brundin. Alcyonarien des Zool. Museums in Upsala, 1896, p. 20.
Euplexaura Kükenthal. Japanische Gorgoniden, II. Teil, 1909, p. 6.

The orginal description of the genus is as follows :

"In external characters it resembles Plexaurella, with rather large, open cells. The spicula
are mostly stout, blunt, warty spindles, and rarely small, irregular crosses".

! 2

Wrighi and Studer add to tlii^ description the character of the axis, which is really the
besl diagnostic feature of the genus. After quoting Verrill's definition they add:

■ ro this may be added that in the structure of the axis there is a general resemblance
to th.a of relia".

In spite ot' this "genera] resemblance", however, there is a very distinct difference between
the a\is of /' lla .nul that "t Euplexaura. In ;i cros-, section «'f a branch of a typical

species of P lla the clear, h<>niy core is surrounded by ;i thick envelope which is composed

<>t' .1 number of long, vermiform, white calcareous bodies enclosed in a casing of chitin. In a
similar section of Euplexaura no such definite structure of the axis is seen; but there is a
central core ,,i pure, translucent, horny material around which is a thick cylinder of horny
material extensively impregnated with lime salts. These latter sometimes scem to take the forra
of fibres, luit are nut nearly so distinct and white as the vermiform bodies of Plexaurella.
The axis of the latter genus is excellently well illustrated by Köixiker, Icones Histologie^, II,
plate XIV, fig. S. It has also been deseribed and figured by the present writer 1.

K ki NiiiAi has emended the definition of this genus in so satisfactorv a manner that
we ma) adopt his diagnosis, which is as follows:

"Koloniën in einer bbene verzweigt. Polypen fast stets ohne gesondertc Kelche direkt in
das dicke Ccenenchym zurückziehbar. Polypen stets mit konvergierenden Reihen von S])indeln
bewehrt, unter denen horizontal angeordnetc liegen. Die Rinde enthalt an der Oberflache dicke,
meist ovale Spindeln und Doppelspindeln, die dicht mit grossen Warzen besetzt sind, darunter
n kleinere, schlankere Spindeln mit regelmassigen Dornengürteln. Achse fast stets etwas
verkalkt und wenig biegsam. Die Farbung samtlicher Arten schwankt zwischen weiss, gelblich
und hellbraun".

The type of the genus Euplexaura is Euplexaura capensis Verrill. The other known
species are Euplexaura pinnata Wright and Studer, E. rhipidalis Studer, E, parciclados Wright
and Studer. /:'. anastomosans Brundin, E. curvata Kükth., E. robusta Kükth., E. crassa Kiikth.,
E. abietina Kükth., E. sparsiflora Kükth., E. erecta Kükth., E. albida Kükth., E. braueri Kükth.,
/;. paria Kükth., and the new species about to be described.

i. Euplexaura rubra new species. (Plate III, figs. 3, ,,<?: Plate IV, fig. 7).

Stat. 164. 1 42'. 5 S., I30°47'.? \'.. Near New Guinea. 32 meters.

ilony incomplete, about 8 cm. long. The basal part is lacking, and it appears that

we have but the terminal portion of the main stem. or large branch, giving off two small

il branches on one side, and one on the other. The stem and branches are round in section,

r of the tonner being 2.5 mm. and of the branches about 1.5 mm. The calyces are

rather prominent for this family, and are equally distributed on all sides of the branches.

The individual calyces are coninal in form, a typical one measuring about 1 mm. in
ight and 1.4 mm. across the base. The poKps are compleiely retractile, the summits of the

illetin from the Laboratories "f Natura] History of the State University ol I

. 8, 9 and 10.

13

calyces closing over them, but showing an eight-rayed margin. The polyps are very small, and
it is dimcult to make out their characters of spiculation on account of the intimate cohesion
of the polyp and calyx walls. It seems, however, that there are a few spindles longitudinally
arranged on the walls and tentacles.

A cross section of a branch shows the ordinary features of this family, except the structure
of the axis cylinder. This has a very decided intercalation of lime salts, the axis appearing to
be composed of fibres between which are deposited the calcareous particles in such quantities
that the axis boils violently when immersed in dilute acid. The watervascular canals seem fewer
and more widely separated than is common in the Plexauridae.

Spicules. These are all densely tuberculated spindles which are so short as to become
oval in outline, and to resemble the disk-like forms of some species of Placogorgia. There is
little variation, except in size, probably due to age.

C o 1 o r. The colony is scarlet throughout, except the polyps, which still show a yellowish
color in alcohol and were probably bright yellow in life.

2. Euplexaura mollis new species. (Plate III, figs. 4, <\ct\ Plate IV, fig. 8).
Stat. 299. io°52'.4S., i23°i'.iE. Cyrus Bay, Rotti Island. 34 meters.

Colony incomplete, flabellate and reticulate. The proximal part is missing, the specimen
being 27 cm. in height and 15 cm. broacl. The main stem, or branch, forks about 3 cm. from
its proximal end, and behind this forking a thick stump of a branch is directed backward and
a little downward. One branch of the fork is cut off 6.5 cm. from its base and is connected
by heavy anastomoses with the other branch. This latter forms the main part of the colony, a
central stem proceeding nearly to the periphery where it is dissipated in the reticulation. The
ultimate twigs are slender and but little over 1 mm. in diameter. The calyces are distributed
on all sides of the branches, their openings being about 1 mm. apart.

The individual calyces are alm os t entirely included in the ccenenchyma, and show externally
as low, dome-shaped verrucs with small round apertures, in the dried specimen. The polyps
are small and retracted so that their infolded tentacles are almost on a level with the calyx
margin in alcoholic specimen. The margin is lined with an eight-lobed membrane caused by the
infolding of the cesophageal region of the polyp. The infolded tentacles are provided with a
pseudo-operculum much like that of the Muriceidse.

A cross section of a branch shows a moderately thick ccenenchyma with two layers of
spicules imperfectly divided by the series of watervascular canals, but not showing two distinct
kinds of spicules. The axis cylinder is full of intercalated particles of lime salts, as in the last
species, and effervesces violently in weak acid solution.

Spicules. The spicules of this species are all small, even minute, in comparison with
others of the family. The most common form is a small terete spindle with relatively large tubercles
arranged in definite whorls. There are also minute globular forms, crosses and dumb-bells.

'I

I'hc small si/c of the spicul ders the surface much smoother than is usual, and the

hyma is sponge lik' in texture.

loi rhe colonj is dull, rather light, brown, or dust color.

3. /' 'iculata new spi 1 Plate III, figs. 2, 2a-, Plate 1\'. lig. 9).

i N - Paternoster [slands. 521 metei . I oral.
E. Kwandang Bay, North Celebes. Sn meters. Sand ;ind coral.
144. Aitchorage north of Salomakiëe (Dam. in Island. 45 meters, ('oral bottum and
Lithothamnii m.

rhe type of this species is .1 mere fragment, but is plainly different from others of this

- in the collection. Colony flabellate and reticulate, the part preserved being evidently from

the margin of the colony and showing the anastomoses of the branches. The fragment

2 cm. long, and consists ot a main branch which gives off two branchlets from one side.

rhe lower of these gives origin to three short stubs of branches trom its outer side and sends

forth another on the opposite side. which anastomoses with the main stem. The greatest diameter

of the stem, near the base is 2 mm., and the least diameter of twigs is 1.2 mm. The calyces

seem t" be more unevenly distributed than in other species, being almost contiguous in some

places and as mnch as 2 mm. apart in others.

rhe individual calyces, while not much exserted, have sharply cut margins and are
therefore more pronounced than in other species of the genus in the collection. When open
they have the ferm of low truncated cones, and when closed they appear as low domes. When
the polyp is fully retracted a series of eight points are seen directed towards the centre. These
points constitute a pseudo-operculum on the dorsal side of the retracted tentacles. Each opercular
flap consists of several spindles arranged en chevron on the proximal part of tentacle, and
a number of longitudinal spindles on the distal part. There is also a well marked collaret.

\ section of a branch shows the same features as have been described in the preceding
species. The axis contains a number of calcareous fibres that can be separated by boiling in potash.

Spicul es. The spicules are mainly small. but hardly minute, terete spindles which are
ely tuberculate, the tubercles seldom appearing to be in definite whorls. The spindles are
quite uniform in character.

flor. Th<- fragment is light grayish brown.

Tv imens of this species were found in the collection aftcr the above description

written. They are much larger than the type, but neither is complete. One of them is
1 2 cm. in length, and both are plainly reticulate.

Hicksonella new genus.

Plexauridse with a thick ccenenchyma, calyces included and on all sides of the branches,
i cylinder, and two very different types of spicules. < >ne type consists of very small,
spindles, and the other of comparatively large, slender, bar-like, smooth spindles
i length of 1.2 mm.

15

The type species of this genus is Hicksonella princeps Nutting.

Just as the two types of spicules furnish the generic distinction that is most prominent in
the genus Plexauroid.es, so two very different forms of spicules are here used as the diagnostic
features of the genus Hicksonella, which the author takes pleasure in naming after the accomplished
naturalist Professor Sydnev J. Hickson who has done such important work in the Alcyonaria.

i. Hicksonella princeps new species. (Plate III, figs. i, \a\ Plate IV, fig. 10).

Stat. 240. Banda Anchorage. 9 — 45 meters. Sand and coral.

Stat. 315. Anchorage East of Sailus Besar, Paternoster Islands. Up to 36 meters. Coral and
Lithothamnion.

Colony densely arborescent, forming a profusely branched clump 1 7 cm. in height and
15 cm. in diameter. Immediately above the base the colony divides into two large trunks, each
of which divides in an irregular manner until braaches of the seventh order are sometimes
attained. The larger branches tend to divide by sending off branchlets in the same plane, thus
forming a palmate structure of the main branch. Many of the secondary branches send off a
number of closely approximated branchlets from one side. The distal portions of the colony
consists of very numerous twigs in dense tufts, the ultimate branches being very short. The
diameter of the colony at base is 1.3 cm., of the main branches .5 cm. and of the ultimate
twigs 3 mm. Some of the larger branches are somewhat flattened, but the others are round.
The calyces are thickly implanted on all sides of the stem and branches. In alcoholic specimens
they are in the form of very low verrucse, which are much less pronounced in dried specimens.

The individual calyces are included, small, round, with their margins but slightly elevated
above the level of the ccenenchyma. The openings are usually quite round, but are sometimes
oval. The polyp in retraction sinks far below the surface. Inside the calyx margin is a propor-
tionately small border with eight undulations surrounding a central aperture below which the
retracted tentacles lie.

A cross section of a branch shows a thick ccenenchyma, large and regularly arranged
watervascular canals, and a horny axis cylinder with an exceptionally small central core of
white noncalcareous substance. No definite layers of spicules can be made out, although there
seems to be a distinct pellicle of ccenenchyma between the watervascular canals and the axis.

Spicules. These are of two very distinct kinds. By far the more numerous are quite
small, short, densely tuberculated spindles, so short as to be oval in outline and entirely covered
with verrucae. The second type is comparatively large slender, almost smooth, bar-like or terete
spicules attaining a length of 1.3 mm. Often one half is quite smooth and glassy, while the
other is finely tuberculate, the tubercles being very small. I am unable to find any definite
anatomical relations of these large spicules. In some cases their blunt smooth points were seen
projecting outward from the calyx walls. They are sparsely and irregularly distributed.

C o 1 o r. The colony is light buffy brown. The spicules are colorless.

A specimen of this species labeled from Station 315 is 95 cm. in length. In the one from
Station 240 the large spicules are sometimes arcuate, but otherwise resemble those described above.

16

Psammogorgia Verrill.

ill. American Journal <>f Science and Arts, XLV, 1868, p. 413.
Verrill. IVansactions Com my of Sciences, Vol. I, Part 2, 1867 — yi,

p. 414.

• and Studer. Challengei Reports, the Alcyonaria, [889, p. ux.
/'.>..". Nutting. Alcyonaria of the Californian t » >.i--t . Proceedings "f the LI. S. National

Museum. Vol. XXXV, 1909, p.

The original description of this genus by Verrill is as follows:

'Corallum dichotomous or subpinnate, with round branches. Axis horn-like. Ccenenchyma

moderately thick, the surface finely granulated with smal! rough spicula. Cells scattered, some-

times flat, more frequentl) raised in the form of rounded verrucae. Polyps with rather large

ated, slender, warty spindles at the bases of the tentacles. Spicules of the ccenenchyma

mostly short, thick and very rough, warty spindles and rough, warty clubs of moderate size".

As the author lias remarked on another occasion (loc. cit.) this genus dons not conform
very well t<> the accepted characters of the family Plexauridae, particularly in the absence of
regularity in the disposition of the watervascular canals.

The species grouped together by professor Verrill under the name Psammogorgia seem
to be nearer this family. however, than any other thus far described, and the present writer
prefers to follow Verrill in regarding it as an aberrant <^enus of Plexaurida- rather than to
raise it t<> family rank.

The type of the genus is Psammogorgia arbuscula Verrill. The other known species
are Psammogorgia fusca Verrill, P. fucosa Verrill, P. gracilis Verrill, P. simplex Nutting,
P. spauldingi Nutting, P. leres Verrill and P. torreyi Nutting.

1. Psammogorgia arbuscula Verrill.

Echinogorgia arbuscula Verrill. Proceedings Boston Society of Natural History, Vol. X,

1866, p. 329.
Psammogorgia arbuscula Verrill. American Journal of Science and Arts, XIV, 1868, p. 413.
Psammogorgia arbuscula Verrill. Transactions Connecticut Academy of Arts and Sciences.

Vol. I. Part 2, [867 — 71, p. 414.
Psammogorgia arbuscula Nutting. Alcyonaria of the Californian Coast, 1909, p. 719.

,3'.8 S., [32°48'.8E. Between Kei Islands. 560 meters. Mud.

1 ilony subflabellate in form, attaining a height of 22 cm. About 3 cm. from its base

the main stem divides into three branches, two of which are subequal and form the main part

of the colony. The third is smaller and bears two short, distant branches on the same side.

The other two are joined by the anastomoses of two branchlets, one from each. One of them

off two other branches trom one side, and the other bnt one. The terminal branches are

all long and slender, in one case attaining a Iength of about 19 cm. They are of about the

diameter 3 mm.) throughout. The calyces are unevenly distributed on all sides of the

. although there are long bare species on the back of some of the branches. Otherwise

the\ ibout 2.5 mm. apart.

17

The individual calyces are very low verrucse, scarcely elevated above the general level
of the ccenenchyma and about 2 mm. in diameter. The verrucse are surmounted by an eight-
lobed margin. Their walls are filled with spindles which appear to be closely packed without
definite arrangement. The polyps are completely retractile, but are often seen, in alcoholic
specimens, with the tentacles resting above the margin and forming an acorn-shaped mass.

The body walls have eight longitudinal rib-like bands of parallel spindles which continue
over the dorsal surface of the tentacles.

The ccenenchyma is thick, and a cross section of a branch shows that the watervascular
canals are not regular in arrangement. The axis is entirely horny.

S p i c u 1 e s. Slender acute spindles predominate, often with a narrow but well defined
bare zone in the centre. A few clubs are seen, also short, bar-like forms quite distinct from
the numerous slender spindles.

C o 1 o r. The colony is bright coral red, as are the spicules.

General distribution. Panama, and the Pacific Coast of Nicaragua, (Verrill). The
Californian Coast, (Nutting).

SIBOG A-EXPEDITIE XIII i*.

DISTRIBUTION OF THE PLEXAURIDjE COLLECTED BY THE SIBOGA EXPEDITION

List of Stations

at which Plexauridae were collected by the Sibojja Expedition, and a
List of Species collected at each Station.

lTION 19. S°44.5S., ii6°2'.5E. West Coast of Lombok. 18 — 27 meters. River mud. coral, coral
sand. PUxaura flava.

STATION 38. 7°35'.4S., U7°28'.6E. Near Paternoster Islands. 521 meters. Coral. Euplexaura reticulata.

LTION 43. Anchorage off Pulu Sarassa, Postillion Islands. Up to 36 meters. Coral. PUxaura
platy stoma,

Sr.\Ti<iN 58. Anchorage off Seba, Savu. Up to 27 meters. Sand. Plexaura aggregata.

Station 60. Haingsisi, Samau Island, near Timor. 23 meters. Lithothamnion in 3 meters and less.
Reef. PUxaura flava.

StaTïOH o'S., [20°34'.sE. üepth changing rapidly from 400 — 120 meters. Coral bottom.

/ 'Uxaura aggregata.

STATION 117. i°o'.5 N., 122 "56 'E. Kwandang Bay entrance, North Celebes. 80 meters. Sand and
coral. Euplexaura reticulata.

STATION 142. Anchorage off Laiwui, coast of Obi Major. 23 meters. Mud. Plexaura flava.

STATION 144. Anchorage North of Salomakü (Damar) Island. 45 meters. Coral bottom and Litho-
thamnion. Euplexaura reticulata.

STATION 162. Between Loslos and Hinken Islands, West Coast of Salauatti. iS meters. Coarse and
fine sand. with clay and shells. PUxaura attenuata.

Station 164. 1 \i. 5 S., i30°47'.5 E. Near New Guinea. 32 meters. Sand. smal! stones and shells.
PUxaura attenuata, Euplexaura rubra.

STATION 213. Salcyer Anchorage and surroundings. Up to 36 meters. Mud with sand. PUxaura
regata.

STATION 240. Banda Anchorage. 9 — 45 meters. Hlack sand, coral, Lithothamnion bank in 18 — 36
meters. Hicksonella princeps.

Station 258. Tual Anchorage, Kei (slands. 22 meters. Lithothamnion, sand and coral. Plexaura
ata, PUxauroides Un

j ? 1 .s S., i32°48'.8E. Arafura Sea. 560 meters. Solid bluish gray mud. Upper layer
more liquid and brown mud. Psammogorgia arbuscula.

19

STATION 273. Anchorage off Pulu Jedan, East coast of Aru Islands, (Pearl Banks). 13 meters. Sand
and shells. Plexaura flava, P. recta, Plexauroides prcelonga, P. lenzii.

STATION 285. 8°39'. iS., I27°4'.4E. Timor Sea. 34 meters. On the limit between mud and coral.
Lithothamnion. Plexaura attenuata, Euplexaura rubra.

Station 299. io°52'.4S., I23°i'.iE. Cyrus Bay, Rotti Island. 34 meters. Mud, coral and Litho-
thamnion. Plexaura recta, Euplexaura mollis.

STATION 315. Anchorage East of Sailus Besar, Paternoster Islands. Up to 36 meters. Coral and
Lithothamnion. Plexaura aggregata, Hicksonella princeps.

Specimens of Plexaura recta from Pulu Missa near Flores. J. H. DE Siso don.

Plexaura pinnata. Locality unknown, as the label is missing.

The list shows that Plexauridae were collected at 19 of the stations occupied by the
Siboga Expedition. As there appear to be somewhat more than 200 successful hauls from the
bottom it follows that members of this family were secured by about io°/0 of these hauls,
showino- that the family is meagerly represented in this region in comparison with the Muriceidae.
No station yielded more than four species, while one Station (310) yielded no less than 17
species of the Muriceidae.

But two species of Plexauridae were secured at depths of over 500 meters. One of these
was Euplexaura reticulala, from a depth of 521 meters; another was P sammogorgia arhiscula,
from a depth of 560 meters.

The family thus appears to be largely restricted to moderately shallow water, which may
in part account for the wide difference between the Atlantic and Pacific plexaurid faunae.

The genus Plexauroides is the only one in which species previously recorded are found.
Plexauroides prcelonga has been reported from Australian waters and Ceylon, and P. lenzii is
known to occur near Singapore. Neither of these localities is far from the East Indian region.

So far as the Siboga material bears testimony concerning the distribution of the Plexauridae,
that testimony is negative regarding the occurrence of species in both the Atlantic and Pacific.
It is also a notable fact that the genera Eunicea and Plexaurella, both furnishing numerous
species from the West Indies, are not at all represented in the Siboga collections.

As indicated above, the restricted bathymetric range of most of the known species of
this family may account for the correspondingly restricted geographic range. Caution must be
exercised, however, in drawing general conclusions from the limited information at our disposal.

Literature cited
in the Report on the Plexauridae of the Siboga collection.

. |. A. X. Alcyonarien aus der Sammlung dos Zoolo<dschen Museums in Upsala. Bihang til k.
Svenska Vet.-Akad. Handlingar, Hand 22, Heft IV. N° 3. Stockholm, 1

HASSAING et MlCHELOTTI. Mémoire sur les Coralliaiies des Antilles, Turin, 1860.

GRAY, 1. E. On the Arrangement of Zoophytes with Pinnated Tentacles. Annals and Magazine of Natura!
History, Uh. Series, Vol. 5. London, 1

[Kl 1;. A. [cones histiologicse, oder Atlas der vergleichenden Gewebelehre; 2te Abtheilung, der feinere
Bau iler höheren Thiere; [stes Heft, die Bindesubstanz der Ccelenteraten, Leipzig, 1865.

Ki KENTHAL, W. Japanische Gorgoniden, II. Teil; Die Familien der Plexauriden, Chrysogorgiiden und
Melitodiden. München, 1909.

Lami - 1. F. V. Histoire des Polypiers coralligènes flexibles, Paris, 18

ition Méthodique des Genres de l'ordre des Polypiers, Paris. 1S21.

MlLNE EDWARDS et HAIME. Histoire naturelle des Coralliaires, Vol. I, 1857.

NüTTING, C. C. Alcyonaria of the Californian Coast. Procecdin-s of the U. S. Xatiomd .Museum, Vol. XXXV,
Washin 909.

RlDLEY, S. O. The Coral Fauna of Ceylon, with Descriptions of New Species. Annals and Magazine of
Natura) History, ;th. Series. Vol. 11. London, 1883.

— _ Report "ii the Zoological Collections of Il.M.S. -Alert", London, 1 SS.;.

STUDER, Th. Alcyonarien aus der Sammlung des Naturhistorischen Museums in Liibeck. Separatabdruck
au Mitteilungen der Geographischen Gesellschaft und des Naturhistorischen Museums in

■eek, II. Ser., Heft 7 und S, Lübeck, [894.

A. E. Review of the Corals and Polyps of the West Coast of America. Transactions of the
inecticut Academy "f Arts and Sciences, Vol. I, Part 2, New Haven, 1867 — 71.

Proceedings of the Essex Institute, VI, 1869.

Critical remarks on the Alcyonoid Polyps in the Museum of Vale College, with descriptions of the

Xew Genera. The American Journal of Science and Arts. Vol. Xl.V. New Haven. 181

,111. E. 1'. and : Til. Report on the Alcyonaria collected by Il.M.S. ('hallen-er during the

-76. The Voyage "f Il.M.S. Challenger, Zoology, Vol. XXXI, 1S89.

EXPLANATION OF PLATES

The photographs were made from nature by the author.
The spicules were drawn under the camera lucida by Mr. Dayton Stoner.

PLATK I.

Fig. i. Plexaura rata n. sp. Natura] size. \n, part of branch 5.

Fig. 2. Plcxciurit attenuata n. sp. Natura] size. 2a, part of branch 5.
Fig. 3. Plexaura pinnata n. sp. Natural size. 3a, part of branch 5.

SIBOGA-EXPEDITIE XIII*. C. C. NUTTING. PLEXAURIDAE.

PLATE II.

Fig. i. Plexaura /lava o. sp. Natura] size. i a, part of branch 5.

Fig. 2. Plexaura platy stoma n. sp. Natura] size. 2a. part of branch 5.
Fig. 3. Plexaura recta n. sp. Xatural size. ia, part of branch 5.

SIBOGA-EXPEDITIE XIII*? C. C. NUTT1NG. PLEXAURIDAE.

Q

PLATE III.

Fig. i. Hicksonella princeps n. sp. Natural si/c. i a, part of branch ;.

Fig. 2. Euplexaura reticulata n. sp. Natural size. 2a, part of branch 5.

Fig. 3. Euplexaura rubra n. sp. Natural size. 3*7, part of branch 5.

Fig. 4. Euplexaura mollis n. sp. Natural size. 4a, part of branch 5.

SIBOGA-EXPEDITIE XIII *". C. C. NUTTINO. PLEXAURJDAE.

III

PLATE IV.

i. PUxaura ?ata n. sp. Group of 5 spicules, a, b, c, d, e. 112.

,r;ir<i attenuata n. sp. Group of 3 spicules, a, b and c. 112.
PUxaura recta n. sp. Group of 3 spicules, a, b and c. ■ 112.

4. PUxaura platy stoma n. sp. Group of 3 spicules, a, b and c. < 112.

5. PUxaura pinnata n. sp. Group of 4 spicules, <?, $, c, d. 112.

6. PUxaura flava n. sp. Group of 4 spicules, u, b, 1, d. 112.

7. EupUxaura rubra n. sp. Group of 3 spicules, a, b and c. 112.

luplexaura mollis n. sp. Group of 4 spicules. a, b, c and d. ■ 112.
9. EupUxaura reticulata n. sp. Group of 4 spicules, «, £, c, </. 112.
10. Hicksonella princeps n. sp. Group of 6 spicules, <7. /', c, d, e and ^. 112.

,1 and <!> represent one of the two genera! types, and the rest the other, or tuberculate type.

SIBOGA-EXPEDITIE XIII/<'. C. C. NUTTING. PLEXAURIDAE.

IV

9k

faal

:q> i

10

I

RÊSULTATS DES EXPLORATIONS
ZOOLOGIQUES, BOTANIQUES, OCÊANOGRAPKIQUES ET GEOLOGIQUES

ENTEEPRISES ADX
IUDES NÉEBLANDAISE3 ORIENTALES eQ 1899 1900,

a bord du 8IBOÖA

SOUS LE COMMANDEMENT DE

G. F. TYDEMAN

PUBLIÉS PAE

MA.X "WEBER,
Chef de 1'expédition.

*I. Introduction et description de 1'cxpédition, Max Weber.
*II. Le bateau et son équipemeut scieatifique, 6. F. Tydeman.
*]1I. Re'saltats hydrographiqnes, G. F. Tydeman.
IV. Foraniiuifera, F. W. Wiuter.
*lVöis. Xeuophyophora, F. E. Schulze.
V. Radiolaria, M. Hartman n.
♦VI. Porifera, G. C. J. Vosmaer et I. Ijima ').
VII. Hydropolypi, A. Billard.
* VIII. Stylasterina, S. J. Hickson et M"« H. M. Englaiid.
*1X. Siphonophora, Miles Len9 et van Riemsdijk.
*X. Hydromedusae, O. Maas.
*XI. Scyphomednsae, O. Maas.
*XII. Ctenophora, M»« F. Moser.

*XIII. Gorgonidae, Alcyonidae, J. Versluys, S. J. Hickson et
XIV. Pennatulidae, S. J. Hickson. [O. C. Nutting').

XV. Actiniario, P. Mc Murrich.
*XVI. Madreporaiia, A. Alcock ') et L. Döderlein.
XVII. Antipathaiia, A. J. van Pesch.

XVIII. Turbellaria, L. von Graf f et R. R. von S tammer.
XIX. Cestodes, J. W. Spengel.
*XX. Nematomorpha, H. F. Nier9trasz.
*XXI. Chaetognatha, G. H. Fowler.
XXII. Nemertini, A. A. W. Hubrecht.
XXIII. Myzostomidae, R. R. von S tammer.
XXIV'i. Polychaeta errantia, R. Horst.

XXIV2. Polychaeta sedeutaria, M. Caullery et F. Mesnil.
*XXV. Gephyrea, C. Ph. Sluiter.
*XXVI. Enteropueusta, J. W. Spengel.
*XXMttis. Pterobranchia, S. F. Harmer.

XXVII. Brachiopoda, J. F. vau Bemmelen.
XXVIII. Polyzoa, S. F. Harmer.
*XXIX. Copepoda, A. Scott').
*XXX. Ostracoda, G. W. Muller.
*XXXI. Cirrhipedia, P. P. C. Hoek1).
XXXII. Isopoda, H. J. Hansen.
XXXIII. Amphipoda, Ch. Pérez.
*XXX1V. Caprellidae, P. May er.

XXXV. Stomatopoda, H. J. Hansen.
* XXXVI. Cumacea, W. T. Cal man.
XXXVII. Schizopoda, H. J. Hansen.
XXXVIII. Scrtrestidae, H. J. Hansen.
XXXIX. Decapoda, J. G. de Man.
*XL. Pantopoda, J. C. C. Loman.
XLI. Halobatidae, J. Th. Ou de mans.
*XLII. Crinoidea, L. Döderlein1) et C. Vaney. .
*XLIII. Echinoidea, J. C. H. de Me ij e re.
*XLIV. Holothurioidea, O. Ph. Sluiter.
*XLV. Opbiuroidea, R. Kohier.
XL VI. Asteroidea, L. Döderlein.
*XLVII. Solenogastres, H. F. Nierstrasz.
*XLVIII. Chitonidae, H. F. Nierstrasz.
*XLIX'. Prosobranchia, M. M. Sehepman ').
*XLIX2. Prosobranchia parasitica, H. F. Nierstrasz et M. M.
*L. Opisthobranchia, R. Bergh. [Sehepman.

*LI. Heteropoda, J. J. Tesch.
*LII. Pteropoda, J. J. Tesch.

LUI. Lamellibrancbiata. P. Pelseneer et Ph. Dautzenberg.
*LIV. Scaphopoda, MUe M. Boissevain.

LV. Cephalopoda, L. Joubin.
*LVI. Tunicata, C. Ph. Sluiter et J. E. W. Ihle ').
LVII. Pisces, Max Weber.
LVIII. Cetacea, Max Weber.
LIX. Liste des algues, Mme A. Weber.
*LX. Halimeda, MUe E. S. Barton. (Mme E. S. Gepp).
*LXI. Corallinaceae, Mme A. Weber et M. F os 1 ie.
LXII. Codiaceae, A. et Mme E. S. Gepp.
LXIII. Dinoflagellata. Coccosphaeiidae, J. P. Lotsy.
LXIV. Diatomaceae, J. P. Lotsy.
LXV. Deposita marina, O. B. Böggild.
LX VI. Résultats géologiques, A. Wichmann.

Siboga-Expeditie

r

rJ0

THE

«ONACEA OF THE SIBOGA EÏPEDMÖI

IV. THE PLEXAURIDyE

BY

C. C. NUTTING

Professor of Zoology, State University of Iowa
With 4 plates

Monographie XIII bx of:

UITKOMSTEN OP ZOOLOGISCH,
BOTANISGH, OGEANOGRAPHISGH EN GEOLOGISCH GEBIED

verzameld in Neder landsch Oost-I ndië 1899 — 1900

aan boord H. M. Siboga onder commando van
Luitenant ter zee ie 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

TWIWrT

E. J. BRILL

LEIDEN

Publié Mai 1910

« Les numéros avec un astérique ont déja paru ; ceux marqués 1) seulement en pattie

Voor de uitgave \\\n 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 Waai. Oud-Consul-Generaal der Nederlanden te Kaapstad.

M B. te Amsterdam.

CONDITIONS GÉNÉRALES DE VENTE.

i°. L'ouvrage du tSiboga" se composera d'une série de monographies.

2'. Ces monographies paraitront au fur et a mesure qu'elles seront prètes.

3°. Le prix de chaque monographie sera different, mais nous avons adopté comme base générale du prix de
vente: pour une feuille d'impression sans fig. flor. O.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.

40. Ii y aura deux modes de souscription :

a. La souscription a l'ouvrage complet.

b. La souscription a des monographies séparées en nombre restreint.
I)ans ce dernier cas, le prix des monographies sera majoré de 25 °/0.

50. L'ouvrag< uni en volumes avec titres et index. Les souscripteurs a l'ouvrage complet re*evront

ces titres et index, au fur et a mesure que chaque volume sera complet.

Déja paru: c . Frix:

** •*■ Souscription Monographies

al'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. Avcc Liste des

Stations et 2 cartes * '...... n 6.75 q..

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. XL VII) 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. — „ 3.75

7e Livr. -(Monogr. XVI a) A. Alcock. Report on the Deep-Sea Madreporaria of the Siboga-
Expedition. With 5 plates ' B 4.60 „ 5.75

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

Mit 4 Tafeln und 3 Figuren im Text B 3. — v 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 „ 2.40 „ 3. —

10e Livr. (Monogr. XI) Otto Maas. Die Scyphomedusen der Siboga-Expedition. Mit 12 Tafeln. „ 7.50 „ 9.50

ue Livr. (Monogr. XII) Fanny Moser. Die Ctenophoren 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 „ 9. — „ 11.25

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

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

16e Livr. (Monogr. Lil) J. J. Tesch. The Thecosomata and Gymnosomata of the Siboga-
Expedition. With 6 plates „ 3.75 n 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 „ 12.50 „ 15.50

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

the Siboga Expedition. With 3 plates • . „ 1.50 B 1.90

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

2e Partie. Ophiures littorales. Avec 18 Planches „ 10.25 „ 12.75

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

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

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

2 plates and 4 text-figures „ 1.80 „ 2.40

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

Supplement zu der I. Abteilung. Die socialen und holosomen Ascidien. Mit 1 Tafel. „ — .75 „ 1.—

I'rix :
■ , ii Uonogni
a l'ouvragc conplol iep

I ivr. M '. Rud. Bcrgh. Die Opisthobranchiata dor Sttx ped. Mit 20 Tafeln. , 11.25 . 14.10

! ■ \ Otto Maas. l>i< 1 raspedoten Medusen der Siboga-Exp. Mit 14 Tafeln. . 9.25 , 12.50

XIII ..■ J. Versluys. 1 onfden der Siboga-Expedition.

II. Die Primnoidae. Mit 10 Tafeln, 178 Figuren im Text und einer Kartc . . . „ 12.50 , 16.75

XXI G. Herbert Fowler. The Cbaetognatha of the Siboga Expedition.

With 3 int- „ 4.20 „ 5.25

LI J. J. Tesch. Die Heteropoden der Siboga-Expedition. Mit 14 Tafdn. „ 6.75 B 9. —
30* Livi \\\ G. W. Muller. Die (Mracoden der Siboga-Exped. Mit 9 Tafeln. „ 3.50 „ 4.40

31» I ■ Franz Eilhard Schulze. Die Xenophyophoren der Siboga-Exped.

Mit 3 Tafeln , 2.40 , 3.—

Ionogr. LIV) Maria Boissevain. The Scaphopoda of the Siboga Expedition.
With 6 plates and 39 textfigures , 4.80 „ 6. —

Livi Monogr. XXVI J. W. Spengel. Studiën übêr die Enteropneusten der Siboga-Exp.

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

34c Livr. (Monogr. XX) H. F. Nierstrasz. Die Nematomorpha der Siboga-Exp, Mit 3 Tafeln. „ 2.80 „ 3.50

35<- Kille) Sydney J. Hickson und J. Versluys. Die Alcyoniden der Siboga-

Bxped. I. Coralliidae, II. Pseudocladochonus Hicksoni. Mit 3 'Tafeln und 16 Figuren im 'Text. „ 2.20 , 2.75

.:. Monogr. XXXIa] P. P. C. Hoek. The Cirripedia of the Siboga Expedition.

A. Cirripedia pedunculata. With 10 plates „ 5.40 , 6.75

37c I.ivr. (Monogr. XLIIa) L. Döderlein. Die gestielten Crinoiden der Siboga-Expedition. Mit

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

Livr. Monogr. IX Albertine D. Lens and Thea van Riemsdijk. The Siphonophores

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

39c Livr. (Monogr. XLIX'a) 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 „ 4.S0 „ 6. —

40* I.ivr. (Monogr. XI.» J. C. C. Loman. IJie Pantopoden der Siboga-Expedition. Mit 15

Tafeln und 4 Figuren im 'Text . „ 6.25 „ 7.S0

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

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

42<-- Li\r. (Monogr. XLIX1) M. M. Schepman und H. F. Nierstrasz. Parasitisohe Proso-

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

43e Livr. (Monogr. XLIX1^) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

Part II. Taenioglossa and Ptenoglossa. With 7 plates „ 4.50 B 5.60

Livr. (Monogr. XXIX.z Andrew Scott. The Copepoda of the Siboga Expedition.

l'.irt I. I lee-swimming, Littoral and Scmi-parasitic Copepoda. With 69 plates. . „ 26. — „ 32.50

45c I.ivr. (Monogr. LVI/>) C. Ph. Sluiter. Die Tunicaten der Siboga-Expedition.

II. Abteilung. Die Merosomen Ascidien. Mit 8 Tafeln und 2 Figuren im Text. j 5.75 „ 7.25

46c Livr. (Monogr. XLIX'r) M. M. Schepman. The Prosobranchia of the Siboga Expedition.

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

47e Livr. iMonoj^r. XIII h C. C. Nutting. The Gorgonacea of the Siboga Expedition.

III. The Muriceidx. With 22 plates „ 8.50 , 10.75

I inogr. XIII/''j C. C. Nutting. The Gorgonacea of the Siboga Expedition.

IV. 'The Plexauridz. With 4 plates „ 1.60 , 2. —

I flor. = Mrk 1.70 = I sri. 8 d. = frs 2.12 en chifTres arrondics.