Land-Mollusks from Java. 399 



einzelne Thier hat einige Eigenthliraliclikeiten, welclie die 

 Vevmuthung nalie liegen, dass reicheres Materiel ziir Auf- 

 stellung einer dritten Gattung oder TJntergattung zwingen 

 wird. Man wird mir erlauben, mich vorlaafig ia der 

 Gliederung zu bescliranken. 



" Die Unterschiede liegen theils in der Hautskulptur, tlieils 

 in der Schale, theils im Penis." {3, p. 109.) 



The peculiar studded appearance of the mantle ani the 

 general form of the animal are scarcely done justice to in 

 Simroth's figure (3, t. vii. fig. 4). 



The whole of tlie mantle, except the thin border sur- 

 rounding the shell, is studded with a dense series of wart-like 

 bodies ; these also appear on the postero-lateral portions of 

 the body (PI. VII. figs. 3, 4, and 5). When examined 

 with a pocket-lens these are seen to be irregular in size, with 

 still smaller protuberances between the larger ones (PI. VII. 

 fig. 6). The microscopical structure of the mantle agrees 

 in all particulars with that of M. javanica, described below. 



To Simroth's description of the shell I am unable to add 

 anything, for in all the three specimens none are exactly 

 alike. One point, however, seems worthy of notice ; in what 

 I take to be an old specimen the shell is much thicker and 

 the periostracum shows a tendency to fold itself beneath the 

 calcareous plate, and so gives rise to a slightly thickened rim. 



The third point Simroth [op. cit.) mentions is the form of 

 the penis, and here there are many important differences from 

 such species as J/. Frukstorferi^ Simr., and M. Bottgen', which 

 I have compared with M. javanica and discussed below. 



The Generative Organs. — Simroth's two figures (3, t. vii. 

 fig. 13 ; and A, t. xv. fig. 23) of the generative organs are so 

 very different from one another, I have considered it desirable 

 to refigure the same from my own dissections for purposes of 

 comparison. 



The vestibule is small ; looked at dorsally (PI. VII. fig. 7) 

 the vagina is seen to open on the left dorsal side, whilst the 

 penis opens into the middle portion, also dorsally. We may 

 divide this latter organ into two parts — a proximal one, having 

 a globose tubular appearance, at the distal end of which the 

 retractor muscle is inserted, and a distal portion, which is the 

 longer of the two, which passes into the vas deferens. In- 

 ternally the cavity of the penis, commencing from the distal 

 end, is a fine tube, which gradually widens and at the end of 

 the distal division gives off a short blindly-ending portion ; 

 below this it passes as a slightly narrower tube into the 

 proximal division running forward; then making a U-shaped 

 bend, it opens into a sac-like expansion, followed by two 



27* 



