172 MOLLUSCA. 



proceeds to the liver on the left. The larger branch is again 

 divided, the smaller branch proceeding to the stomach. The 

 largest trunk that remains, before it leaves the pericardium, 

 has two singular bodies attached to it, consisting of com- 

 paratively large vessels, opening from this aortic branch. 

 The use of these glands is unknown. The organs of gener- 

 ation likewise exhibit some remarkable peculiarities. The 

 ovarium is situate in the posterior part of the abdomen. The 

 oviduct is tortuous in its course, passes along the surface of 

 the testicle, and, after uniting with a clavate appendage, 

 opens into a common canal. The testicle is firm, apparently 

 homogeneous in its texture, of a yellow colour, with spiral 

 ridges on its surface. The vas deferens arises from a com- 

 plex, glandular body, and unites with the common canal. 

 This common duct, before it reaches the external orifice, 

 receives the contents of the pedunculated vesicle, and has 

 attached to it a botryoidal, glandular organ, the use of which 

 is unknown, but which some suppose to be employed to se- 

 crete an acrid liquor regarded as venemous. It is obvious 

 from this structure, that the seminal fluid and eggs must 

 come in contact in the common canal, and at the single ori- 

 fice, provided they are both ejected at the same time. From 

 the orifice to the right fore-feeler there is a sulcus, leading 

 to the pore containing the retractile penis. This organ, 

 like those of the other mollusca, is solid. It terminates in 

 a small filament. The external groove is the only connec- 

 tion between it and the other sexual organs. 



There is a peculiar secretion of a purple fluid which here 

 deserves to be recorded. It issues from a spongy texture, 

 underneath the free side of the dorsal plate. Connected 

 with this cellular reservoir is a glandular body of a consider- 

 able size, which is supposed to secrete the coloured fluid. 



