256 THE CEPHALOPHORA. $ 225, 
organs. These are either combined in one individual, or the sexes are sep- 
arate. In most species there are copulatory organs, The genital organs: 
have several uneven divisions, which, when fully developed, are arranged 
as follows: A Tuba Fallopii passes from the ovary into the uterine sa, at 
whose base is an organ which secretes albumen, while at the point where it. 
is continuous with the vagina, there is a Receptaculum seminis. The male 
genital organs consist of a testicle, a Vas deferens, and a Ductus ejaculato-. 
rius which opens into a retractile penis. With the hermaphroditic species, 
these two kinds of genital organs are more or less blended together, — the 
testicle with the ovary, and the Vas deferens with the Tuba Fallopi ; very 
often also the vagina is united with the Ductus ejaculatorius, forming a- 
cloaca into which open several particular secreting organs. These differ- 
ent male and female organs are usually lined internally with ciliated 
epithelium. 
The eggs of these animals have, at their escape from the ovary, a round 
and sometimes an elliptical form, and are composed of a thin chorion en- 
closing a finely-granular vitellus of variable color, which contains a 
germinative vesicle and dot.” The sperm is white and opalescent, and. 
quite crowded with very active spermatic particles. These last are either 
of the form of Cercaria, or consist of a very long filiform body, one extrem- 
ity of which is incrassated and often of a spiral form. The trembling, 
undulatory movements of these particles cease when placed in water, with 
those species which have copulatory organs ; they become twisted into loop-- 
like forms and are finally rigid and motionless. 
1 See Carus, Erlauterungstafeln Hft. V. Taf. IT. 
fig. 4, al. (Limaz), and in Muller's Arch. 1835, p. 
491, Taf. XII. fig. 2 (Helix pomatia); Wagner, 
in Wiegmann’s Arch. 1835, I. p. 368, and Pro- 
dromus, loc. cit. p. 7, Tab. I. fig. 6, 7 (Helix and 
Buccinum) ; and Allman, loc. cit. p. 152, Pi. VIL. 
fig. 7 (Actaeon). 
2 Wagner and Erdl (Froriep’s neue Notiz. No. 
249, p. 98) have found with Chiton, Patedia, and 
Haliotis, spermatic particles of a Cercarian-form, 
that is with along body to which is abruptly at- 
tached a hair-like tail. Ihave seen a similar form 
with Vermetus gigas and triqueter. .'Those of 
Trochus also have this form, according to Kélli- 
ker (Beitr. loc. cit. p. 28), but the middle of their 
body has a slight constriction. They are hair-like, 
and taper at both extremities with Turbo, Bucci- 
num, Purpura (Kélliker, loc. cit. p. 25, Taf. I. 
fig. 5), and Sagitta (Krohn, loc. cit. p. 10, fig. 12). 
With other marine Gasteropoda, as for example, 
Carinaria, these partioles are hair-like, but with 
one of their extremities slightly incrassated (Milne 
Edwards, Ann. d. Sc. Nat. XVIII. p. 324, Pl. XI. 
fig. 7); and with Doris, Tergipes, and Paludina, 
this thickened extremity has a spiral form (K dlli- 
ker, Beitr. loc. cit. p. 35, Taf. I. fig. 6; Nord- 
mann, loc. cit. p. 52, Taf. III. fig. 8,9, and my 
observations in Muller’s Arch. 1836, p. 240, Taf. 
X.). With the pulmonate Gasteropoda, the sperm- 
atic particles have only a short incrassated extrem- 
ity of a spiral form ; see my observations loc. cit. 
1886, p. 45, Taf. II.; Paasch, in Wiegmann’s 
Arch. 1843, I. p. 71, Taf. V., and Dujardin, Ob- 
serv. au Microscope, Atlas, Pl. III. 
The development of these spermatic particles 
takes place in two large cells (Mother-cells), in 
which are formed others (Daughter-cells) which are 
changed into the spermatic particles. But the cell- 
membrane of the mother-cell, disappears quite 
* [§ 225, note 2.] My own observatioss on the 
spermutic particles of the Cephalophora and their 
early and its contents are condensed into a solid nu- 
cleus around which are grouped the daughter-cells, 
ultimately forming a bundle of spermatozoa. See, 
beside these observations of Kélliker, Nordmann, 
and Paasch, loc. cit., those of H. Meckel, in Mul-- 
ler’s Arch. 1844, p. 483, Taf. XIV. fig. 9-13, and 
the more recent researches of A dliiker, in the Neue 
Denkschrift. d. allgem. schweizer. Gesellsch. f. d. 
gesammt. Naturwissensch. VIII. 1846, p. 4, Taf. 
I. fig. 1-10 (Helix pomatia). 
The presence of two kinds of spermatic parti— 
cles in the sperm of Paludina vivipara, is a very 
remarkable fact ; see my observations in Miller’s 
Arch. 1836, p. 245, Taf. X. 
Beside the hair-like spermatic particles already 
mentioned, there are long cylindrical bodies, from 
one of the extremities of which project mapy deli- 
cate filaments having very lively motions, These 
have been described by Ehrenberg (Symbol. 
physic. Anim. evertebrat. Dec. I. Phytozoa ento- 
zoa, Appendix) as parasites under the name Pha- 
celura paludinae. 
Paasch (Wiegmann’s Arch. 1848, p. 99, Taf. 
Y. fig. 8), on the other hand, regards them as bun-- 
dles of spermatic particles of the normal form, and 
Kolliker (Beitr. loc. cit. p. 63, and Neue Denkschr, 
loc. cit. p. 41) considers them only as two forms. 
of the same kind of spermatic particle; the second 
he regards as elongated mother-cells containing 
many ordinary spermatic particles. 
For my part, I do not know how to explain this. 
fact, and 1 would willingly place the second form 
in the category of Spermatophora ; but against this. 
opinion, as against that of Kolliker, and Paasch, 
it can be urged that, with the second form, the ex- 
tremities are never thickened or spiral, as is true 
of the first, and that both forms are simultaneously 
developed in the testicle.* 
development, cerrespond closely with the above 
account. Their dd -elopment in special ce %s I have 
