152 PROCEEDINGS OF THE MALACOLOGICAl SOCIEXY. 



to a slit in the right border of the mantle, marking the line of 

 junction between the right and left shell lobes which are still free in 

 the genus Macrochlamys. The posterior margin of this slit extends 

 forwards, and is overlapped by the anterior one. The common genital 

 orifice is situated behind to the right tentacle. The foot has a narrow 

 pedal groove, and is marked at its edge with dark lineoles, while the 

 sole shows some slight traces of differentiation into three portions. 



The shell (PI. IX, Figs. 2-2») is to all intents and purposes internal, 

 and is somewhat oval in shape, with a light-coloured periostracum, 

 it is convex above, while on the under side either the original hollow 

 may remain or this may be filled up with shelly matter, even to the 

 extent of rendering the under surface convex. The lines of growth 

 are well marked, and the apex of the shell, which lies on the right 

 side of the posterior end, is directed downwards. An important 

 point is that the viscera are not carried behind the mantle into the 

 foot. The jaw (PI. IX, Fig. 3) is a simple structure, with 

 a prominence in the middle ; while the radula shows a central 

 tricuspid tooth flanked by laterals, with large meso-cones, distinct 

 ecto-cones, and ento-cones (PL IX, Fig. 4) that may be but barely 

 distinguishable ; the typical marginals (Fig. ^a) follow after a larger 

 or smaller number of transitional teeth, and are bicuspid, the meso- 

 and ecto-cones being practically equal in size. 



The genitalia (PI. IX, Fig. 5) seem to be very much like those 

 of Girasia as described by Godwin- Austen. A dart sac is present, 

 shown on the right-hand side in the figure ; a swelling of the free 

 oviduct takes place that appears to be characteristic ; the penis, 

 as in the last-named genus, is sharply bent at the point where an 

 appendix bearing the retractor muscle is given off ; an epiphallus 

 follows which is prolonged as a blunt and short flagellum beyond 

 the insertion of the vas deferens. The sperraatophore (capreolus), 

 so far as it could be made out in M. JDussumieri, is shown in Fig. 6 ; 

 in the spermatheca there were some seven or eight of the shafts 

 without projections; a bunch of these latter was, however, discovered 

 attached to a broken head, and the two have been combined in Fig. 6, 

 to give as correct a representation of the structure as possible. 



This genus is evidently very nearly allied to Oirasia, but differs 

 in the following characters, as pointed out by Godwin-Austen when 

 instituting the synonymous genus Behhania. The depression in which 

 the visceral hump is sunk is squarish, not V-shaped ; the pedal 

 grooves are not so deep nor so well shown, and the segmented margin 

 is narrower ; the orifice in the mantle is much smaller, as also is the 

 shell, which is reduced, while the radula has a larger number of 

 teeth in each row. 



The question as to the dart sac being larger must, one would think, 

 apply to girth, ^ since that of Maric^lla Beddomei seems comparatively 

 larger than that of Girasia Radha, while that of Maricella I)ussumieri 



1 During the reading of this paper Lieut.-Col. Godwin-Austen signified that this 

 was what was meant. 



