$ 97. THE ECHINODERMATA. 9T 
the sg filling the empty spaces between the double rows of ambulacral 
vesicles. 
They consist of widely ramified, deeply interlocked coeca, having always 
proper excretory ducts, which open upon the génital plates of the back of 
the shell.“® There are here always five of these organs, and the genital 
plates, alternating with the ocellary ones, surround the anus.“ In some 
species of the Clypeastridae, and Spatangidae, there are, perhaps, only four 
of these organs, judging from that number of the plates.“ In the Holo- 
thurinae, these organs have a very different arrangement. They consist of 
widely-branched coeca,™ floating, as loose clusters, freely in the cavity of 
the body, and opening through a single common excretory duct, situated 
below the osseous circle, and between the oral tentacles. 
The testicle, which is of a whitish color, consists of a cluster of cylindri- 
eal sacs, branched and interlocked with each other.“ But the ovary is 
pale red, very long, branched, a little flattened, and extends even to the 
posterior end of the body. 
As the only exception among these animals, the Synaptinae are her- 
maphrodites. But it should be stated that we know of them only through 
Synapta Duvernaea. It is said that here the testicles and ovaries are 
united in one and the same organ.©? Three or four long.cylindrical sacs 
float in the cavity of the body, and have an excretory duct which opens 
back of the osseous circle. .At the enoch of procreation, vesicular pro- 
longations appear on their interior surface, in which are formed spermatic 
particles. The spaces between these prolongations are filled by a pultace- 
ous mass, in which appear eggs. 
In the Sipunculidae, and Kchiuridae, there are only two or four simple 
cylindrical contractile pouches attached to the ventral wall. 
It is yet 
undetermined whether their contents escape by rupture, or through special 
openings. 
15 The separate sexes of Echinus were first 
shown by Peters; see Muller’s Arch. 1840, p. 
143, 
16 See Tiedemann, loc. cit. p. 85, Taf. X. fig. 1, 
4, 8 ; and especially Vulentin, Monogr. &c. p. 103, 
Pi. VIIL. 
VW With Echinanthus, Mellita, Rotula, Scutella 
(see Agassiz. Monogr. des Scutelles), and Spa- 
tangus arcuarius, and ovatus, I can count only 
four genital plates, while in Encope, and Clypeas- 
ter, { find five; yet Valentin (Repertorium, 1840, 
p- 801) expressly speaks of five genital organs in 
Spatangus violaceus. 
18 Wagner and Valentin were the first who 
noticed the scxual differences of Holothuria tubu- 
losa; see Froriep’s neue Not. No. 249, p. 99. 
19 See Wagner, Icon. zoot. Tab. XXXII. fig. 11 
'Holothuria tubulosa). I have already remarked 
86), that the white cylindrical pedicella, taken 
by some zovtomists as testicles (Delle Chiaje, loc. 
cit. I, p. 97, Tav. VIII. fig. 1. 0.), are distinct from 
the genital organs, and communicate directly with 
the intestinal canal. 
20 See the Catalogue of the Physiol. Series, &c., 
loc. cit. IV. Pl. XLIX. fig. 1. ¢. (Holothuria tub- 
ulosa). . 
21 Quatrefages, Ann. d. Sc. Nat. loc. cit. p. 66, 
Pl. IV. fig. 1, q. Pl. V. fig. 1. 
22 This deep confusion of the organs of two sexes 
is something so remarkable, that one cannot but. 
believe that Quatrefages has here taken the 
parent sperm cells for the eggs. 
23 In Sipunculus, and Phascolosoma, there is 
observed on each side, a little front of the anus, a 
sac attached to the side of the body (see Delle 
Chiaje, loc. cit. Tav. I. fig. 5, 8. s. and Grube, 
Miuller’s Archiv. 1837, Taf. XI. fig. 1. vo). 
These have been regarded as genital organs. In 
Sipunculus nudus, Grube has found eggs not 
only in these sacs, but in the cavity of the body 
also. It may, therefore, be questioned if the eggs 
escape from the sacs into the cavity of the body, 
whence they are expelled through an opening at its: 
posterior extremity, or if they are accidentally 
introduced from without with the water, during 
respiration. In this last case, these sacs should 
have excretory ducts; and there are, indeed, im 
Sipunculus nudus, two external fossz opposite 
the point of insertion of the sacs (see Delle 
Chiaje, loc. cit. Tav. I. fig. 2, f.), and in which, it 
is said, there are two very small openings. Ac-— 
cording to Forbes and Goodsir, the genital sacs 
of the male Echiurus vulgaris cortain a seminal’ 
liquid, with very active spermatic particles, while 
those of the female are filled witk sggs; see Fre- 
riep’s neue Not. loc. cit. p. 281 fig. 20, 22, 12, 
f. f 
*[§ 97, note 23.) For the sexual organs of Sipunculus, see Peters (Muller’s Arch. 1850, p. 
