I4P Records of the Indian Museum. [Voi,. XVI, 



further species ' from the Shan States to the Indian fauna, namely 

 L. shanensis of which several extinct phases as well as the living 

 form have been described; and the highly peculiar L. mimctica. 



The shell is extraordinarily plastic in Limnaea and it is of 

 great importance that the genitalia, the radula and the structure 

 of the upper jaw should, whenever possible, be examined in the 

 identification of the species. In the genitalia we find the most 

 constant differences in the relative lengths of the different parts of 

 the main ducts, in the form of the penis sheath and in the presence 

 or absence of the spermathecal duct. 



Limnaea acuminata, Lamarck, 

 (Plate V, fig. I). 



tSqo. Linmaea acuminata varr. pafiila and riifescens, Von Martens, Conch. 

 Mitfli. I, pp. 75, 76, pi. xiVj figs. 1-3. 



We confine this name to the forms in which the outer margin 

 of the aperture of the shell is regularly curved, thus excluding 

 both L. chlamys, Benson and L. amygdalum, Troschel. 



The radula (fig. i) is rather broad. The lateral teeth have three 

 distinct cusps ; there are about nine rows of lateral teeth on each 

 side of the central tooth, but there is no very abrupt difference 

 between the lateral and the marginal teeth, of which there are at 

 least twenty rows on each side. The central tooth is practically 

 unicuspid, and the single cusp is narrowly produced. The lateral 

 teeth are very broad, their central cusp is not much larger than 

 the two lateral ones, which are subequal; the outer lateral cusp is 

 considerably nearer the base of the projecting part of the tooth than 

 the inner one. The marginal teeth have from three to six rather 

 short and blunt cusps, the outermost of which is situated near the 

 base of the projecting part. 



The central piece of the horny upper jaw is broad and strongly 

 convex, but hardly beak-like ; it is of a dark brown colour. 



The genitalia are of normal type. The duct of the herma- 

 phrodite gland is short and coarse, never much longer than the 

 gland itself, it does not appear to be swollen at the point at which 

 the male and female ducts diverge. In the male duct the part 

 between the prostate and this point of divergence is slightly 

 longer than that between the prostate and the proximal end of the 

 penis-sheath, which is of considerable length, sausage-shaped and 

 rather narrow. The albumen and accessory glands are rather large 

 in the specimens examined ; they arise close together and are 

 situated much nearer to the uterus than to the hermaphrodite gland. 

 The oviduct is very short ; the uterus is elongate and narrow ; 

 and the sperniatheca, which is pear-shaped when fully mature, is 

 almost sessile. 



1 Annandalc, Rec. hid. Mvs., XIV, pp. 107-109, pi. x, figs. 5, 8, 9, pL xi. 

 fio-s. 2, 3, 4 (1918). 



