550 GASTEROPODA. 



(1468.) Equally simple is the structure of the generative system 

 in the females of the Pectinibranchiate Gasteropods. A large ovary 

 occupies the same position as the testis of the male, and shares with 

 the liver the interior of the windings of the shell. The oviduct gene- 

 rally follows the same course as the vas deferens of the other sex, and 

 is provided with thick and glandular walls. The eggs, which are very 

 numerous, are arranged in long gelatinous ribands, and, after extrusion, 

 are glued in various ways to the surface of rocks, sea-weed, or even to 

 the shells of other Mollusca. Sometimes, in the siphoniferous tribes, as 

 for example in the common Whelk (Buccinum), the ova are enclosed in 

 tough coriaceous capsules secreted by a glandular organ in the vicinity 

 of the oviduct. These capsules contain several eggs apiece, and are 

 joined together in large bunches, such as the waves continually cast up 

 upon every beach. 



(1469.) The Heteropod Gasteropoda are hermaphrodite. In Ptero- 

 trachea the female organs consist of a distinct ovary, uterus, spermatheca, 

 and an auxiliary gland, all lodged in the visceral sacculus appended to 

 the back. The ovary (fig. 269, ^>) is of considerable size, and gives origin 

 to a slender oviduct, which, near its termination, communicates with the 

 receptacle for the ova, called the uterus (g). The spermatheca joins the 

 canal leading from the uterine cavity to the exterior of the body, which 

 likewise receives the secretion of two small glandular sacs (&) apparently 

 destined to furnish some investment to the eggs prior to their expulsion. 



(1470.) The male parts are situated in the general cavity of the body, 

 quite apart from the female apparatus. The testicles seem to be repre- 

 sented by two wavy casca (fig. 269, i), which terminate at the root of a 

 small intromittent organ (s) placed at a short distance behind the open- 

 ing of the vulva. 



(1471.) All the Tectibranchiata, Infer obranchiata, Nudibranchiata, 

 and the Pulmonated Gasteropods are hermaphrodite, having both a male 

 and female generative apparatus arranged upon the same principles 

 as those of the Snail, which have already been described at length ; 

 and to enumerate the variations which occur in the relative position 

 and organization of different parts of the reproductive system in all the 

 genera composing these extensive orders would scarcely answer any 

 useful purpose, even were it practicable within the limits of this work. 



(1472.) In the male Patella, the testicle is situated upon the right 

 side of the body, between the visceral mass and the external envelope. 

 It is of a pale-yellow colour, with a slight pinkish tint, and seems to be 

 entirely made up of minute tubes, many times folded upon themselves, 

 and imbedded in a granular-looking substance. On cutting into the 

 substance of the testicle, there flows out a milky fluid, which the micro- 

 scope reveals to contain innumerable spermatozoa, whose movements are 

 very active as long as the seminal secretion is fresh. 



(1473.) The ovary of the female occupies nearly the same situation 



