400 



GASTEROPODA. 



would seem to form a complete system in 

 itself; yet, on examining the male organ 

 of excitement, we tind it connected with 

 considerable appendages, the nature of 

 which it is difficult to conjecture. The sac 

 (') is muscular, and resembles the mus- 

 cular root of the penis in the genera already 

 described, being, as in them, capable of in- 

 version : at its base are seen two cul-de-sacs, 

 into each of which opens a long and rlexuous 

 caiuil (/, n). The canal marked n is very 

 slender, and when unfolded is four times the 

 length of the body of the animal ; its termi- 

 nation at the point most remote from the mus- 

 cular sac into which it opens is apparently 

 closed. The other tube marked I is much 

 wider and of extraordinary length; its com- 

 mencement^) isextremely convoluted and fully 

 eight times as long as the body ; its walls are 

 thin, but it is supplied plentifully with blood 

 by means of a large artery interlaced with its 

 convolutions ; at A- it becomes enveloped in a 

 fleshy mass of considerable thickness, after 

 which, assuming its original appearance, it 

 proceeds to the cul-de-sac, at the bottom of 

 which it terminates. In fig. B, 198, the muscular 

 cavity (HI) has been laid open, and the mode 

 in which the above tubes enter it has been 

 displayed; the smaller one () ends in a little 

 horny papilla (q) seen in the engraving ; the 

 larger tube (/) terminates by a kind of glans 

 penis, perforated by a large aperture and sur- 

 rounded by a kind of prepuce (p): on open- 

 ing the vessel a little before its entrance into 

 the muscular sac, it is found to conceal a 

 sharp horny dart (o), supported upon a fleshy 

 pedicle, and readily protrusible through the 

 aperture p; the analogy between this singular 

 instrument and the dart of the Snail is ob- 

 vious, for when the muscular sac (m) is 

 everted, the papilla- (f>, rj) become external, 

 and the horny point being pushed out of the 

 former will probably form a stimulus of the 

 same description. 



We have hitherto abstained entirely from 

 mixing up with our description of these prin- 

 cipal forms which the generative system of the 

 mutually impregnating Gasteropoda presents, 

 the discussions which have arisen concerning 

 the real nature of the different organs which 

 have been described, and have designated them 

 by the terms usually applied to the respective 

 parts,without reference to their individual func- 

 tions. It now, however, becomes necessary 

 to lay before our readers the principal opinions 

 which are recorded upon this subject. The chief 

 points of debate have been the bladder, and 

 the organ which we have described under the 

 appellation of testicle. The bladder is, from 

 its constant occurrence, evidently an organ of 

 some essential use : it was regarded by 

 Swammerdam as the secreting structure from 

 which the colouring fluid peculiar to some 

 species is produced," especially in the Murices 

 and others of the marine genera ; it was there- 

 fore named by him sac of (he purple ; but we 

 shall afterwards find that this fluid is derived 

 from another source. Ulainville, on the other 



hand, considers this vesicle as analogous to the 

 urinary bladder of Vertebrata ; in reference to 

 this hypothesis, however, we should be inclined 

 to ask, with Cuvier, where are the kidneys ? and 

 even upon the supposition that the secretion of 

 the bladder itself was analogous to the urinary 

 fluid, we are not aware of any chemical proofs 

 of its nature which are sufficient to establish 

 the identity. Delle Chiaje again sustains that 

 the sac of the purple is, in fact, the testis, and 

 that its secretion, poured as it constantly is 

 into the termination of the oviduct, is in re- 

 ality the fecundating fluid ; yet against this we 

 must urge the distribution of the vas deferens 

 met with in the Helices, which from its entire 

 arrangement converts the organ of excitement 

 in these animals into an apparatus of immis- 

 sion, whose nature cannot be mistaken. The 

 opinion which we consider most consonant 

 with all the circumstances of its position, is 

 that it is a reservoir for the seminal fluid 

 analogous to the spermotheca of certain insects. 

 Cuvier expressly notices the constant relation 

 which exists between the length of the penis 

 and that of the canal which leads to this sac- 

 culus, and when we remark the long chains of 

 ova which are slowly extruded in most of the 

 Gasteropoda, we are readily disposed to admit 

 of the necessity of such a reservoir, which, 

 treasuring up the semen until the eggs are 

 about to be expelled, applies it efficiently to 

 the ova as they successively pass the orifice of 

 its duct. This supposition derives additional 

 weight from what we have found to be the 

 arrangement of the seminal ducts in Vaginulus 

 and Onchidium. In the former we observed 

 that, besides the canal, which, as in the Snail, 

 perforates the root of the penis and thus be- 

 comes subservient to copulation, the vas de- 

 ferens actually pours a part of its contents by 

 a separate canal into the bladder itself, which, 

 as in all cases, communicates with the egg- 

 passage. In Onc/iiiliuni the connexion be- 

 tween the testis and this receptacle is equally 

 striking, as will be obvious on reference to the 

 drawing given above. In Aplysia, Delle Chiaje 

 considers the testicle as described by Cuvier 

 to be in reality the matrix or receptacle for the 

 ova, in which they attain their full development 

 prior to expulsion, basing his opinion upon 

 the disposition of the spiral cavity which it 

 contains. 



We are entirely left to conjecture as to the 

 uses of the other appendages found in par- 

 ticular species, and the multifid vesicles of the 

 Snail, which are wanting even in the Slug, the 

 tortuous canal connected with the penis of 

 Doridium, and the still more singular organs 

 belonging to the male apparatus of Oncliidinm, 

 must still remain the subjects of observation 

 and experiment. 



The third form of the generative system in 

 which the sexes are distinct, is met with in 

 all the Pectinibranchiate order, and in the 

 operculated Pulmonalia of Ferussac. In P>uc- 

 cimun, which we shall select as an example 

 of the general arrangement of the sexual organs 

 in the former, the male is at once distinguish- 



