iNCisuRA (scissueella) lytteltonensis. 17 



It is the commencement of the oviduct. Rapidly narrowing 

 in diameter it passes forward to the right of the posterior end 

 of the stomach and the liver lobes originating from it, and 

 maintaining a position close below the external body-wall, it 

 passes as a very much flattened and very thin-walled duct 

 along the right side of the visceral mass, gradually mounting 

 from a more ventral to a more dorsal position till it arrives 

 above the right-hand loop of the intestine. All this while it 

 has laid close to the outer body-wall, and it is extremely 

 difficult to follow its course, owing to its being flattened 

 between the liver and the external integuments. It turns in- 

 ward just above and in front of the right visceral ganglion 

 and runs in the roof of the posterior end of the mantle-cavity 

 towards the right kidney (fig. 11). Here its walls become 

 thicker and are lined by a distinct cubical epithelium. The 

 duct does not at once enter the kidney but runs along its 

 outer wall and opens into it in close proximity to the renal 

 orifice. As stated above the gonaduct opens into the kidney 

 coincidently with a reno-pericardial canal, the relations 

 being very similar to those in Trochus. The vas deferens 

 takes the same course as the oviduct. 



The alimentary tract. — The buccal bulb is relatively of 

 enormous size. There are two large odontophoral cartilages 

 on either side whose shape, as seen in section, is very similar 

 to that of the cartilages of Fissurella as figured by Boutan. 

 As shown in figs. 6, 7, and 8, the anterior and dorsal cartilages 

 are the larger, and support the radula ; the posterior cartilages 

 lie ventrad of the hinder ends of the anterior cartilages and 

 have concave upper surfaces, with which the hinder ends of 

 the latter articulate. A similar arrangement obtains in 

 Trochus, and has been well described by Randies (15). The 

 musculature of the buccal bulb is powerful, but I have not 

 attempted to follow it out in detail. It is noticeable, how- 

 ever, that the cross-striation, both of the intrinsic and ex- 

 trinsic muscles of the odontophore, is very well marked. 

 Though it is well known that these muscles are cross-striped 

 in Gastropods, I am not aware that the character of the stria- 



VOL. 55, PART 1. NEW SERIES. 2 



