298 ZONITIDJE. 



The only part of this original description which was wrong 

 relates to the tongue-shaped process or shell-lobes : these were 

 seen to be present in the second specimen soaked out ; they are 

 small, particularly the right, and might easily be overlooked in 

 life. This had clearly a pointed foot, not divided beloAv as in 

 Macrocldamys, with an indistinct central fold, no peripodial 

 grooves, very dark grey, a rather smooth surface with a pale 

 narrow peripodial border. 



From the two soaked-out specimens I have been able to make 

 out much more of the genitalia than the first alone presented, 

 which was incomplete (fig. 90, E'). 



The generative organs are most interesting and fall in with the 

 dissimilarity to Zonitoid genera, such as Macroclilamys, presented 

 in the external characters. They are altogether different from 

 any species of Indian Land Molhisca I have hitherto seen, 

 particularly in the form of the dart-sac. The penis is a simple 

 tube bent on itself near the short retractor muscle. The sperma- 

 theca is long and ample. The oviduct in both cases was destroyed, 

 but in the second specimen the junction of the vas deferens was 

 intact. The dart-sac is short, rounded at the distal end, and on 

 being opened out a blunt leathery solid dart was disclosed. 

 Attached to the head of the dart-sac at its central point is a tube 

 of great length : in the first specimen this is thin at first, then 

 SAvelling out much larger in several coils, and again becoming 

 thinner ; in the second specimen this rope-like tube is more 

 uniform in size, much coiled together where it is attached to a 

 glandular mass, this was much broken up, but a large portion 

 was seen enveloping a part of the spermatheca. 



This long rope-like attachment to the dart-sac, which in the 

 first specimen had no attachment, left very much that was 

 doubtful as to what it could be ; the second specimen clears this 

 up, and we are presented with an amatorial organ similar in its 

 main points to that met with in the genus Byalia, particularly 

 in that of I), striata var., described by me in the 'Proceedings 

 of the Malacological Society,' vol. vii, pt. 2, June 1906. 

 This is an extremely interesting point of resemblance — con- 

 fined to one organ, and yet not shared in by several important 

 characters. In Byalia there is a large mucous pore, and the 

 peripodial margin is fringed as in the Zonitidse generally. There 

 are no shell-lobes either. There are minor details in the genitalia 

 which may be noted : the spermatheca in DyaMa is very small, 

 the dart is calcareous. The radula is of the same type in both, 

 the laterals being aculeate. The penis in both is of the same 

 simple type. The radula of the Dafla form has 98 rows of teeth 

 and the formula 



55 . 1 . 12 . 1 . 12 . 1 . 55 

 68 . 1 . 68 



The centre tooth is tricuspid, the admedians also tricuspid, the 

 inner cusp high up, the outer one lower down ; the 13th tooth 



