1886.] 



0. F. von Mollendorff— r/ie LanclsJiells of PeraJc 



315 



and myersi, Haines, from Siam. Of none of these I have been able to 

 compare specimens ; from the published descriptions I glean the follow- 

 ino; differences between the four forms. 



Name. 



gravida. 



onouhoti. 



tnyersi. 



elephas. 



Axis. 



35 



35 



39 



50—57 mill. 



Umbilica- 

 tion. 



Perforate. 



Subumbilicate. 



Narrow. 



Narrow. 



Colour. 



Whitish brown 

 (fusco-albida). 



Deep violet 

 brown (saturate 

 fasco-violacea). 



Incarnate 



brown 



(carneo-fusca). 



Reddish incarnate 

 or orange. 



Sculpture. 



Rather smooth 

 (laeviuscula, 

 vix striatula). 



Slightly striate 

 (striatula). 



Sublsevigate. 



SubloBvigate. 



Last whorl. 



* * # 



* # # 

 Slightly and 



suddenly 

 ascendent. 



Foveolato-mal- 

 leatus. 

 Deeply descen- 

 dent, ascen- 

 dent at the 

 aperture. 



With irregular 



spiral sulci. 



Obliquely 



descendent. 



With distinct rather 

 irregular transverse 

 stripes. 

 Strongly descen- 

 dent, close to the 

 aperture very little 

 ascendent. 



Suture. 



Impressed, 

 m.arginate. 



Not mentioned. 



Slightly 

 impressed. 



Impressed, very 



distinctly mai'gi- 



nate. 



Aperture. 



Circular. 



Angulate oval. 



Angulate oval. 



Almost circular. 



Peristome. 



Whitish, incras- 

 sate, with an 

 inner groove 

 (intus late sul- 

 catum). 



Orange red, 

 duplicate, outer 

 margin at the 

 insertion pro- 

 ducted upwards. 



Incrassate, the 

 upper inser- 

 tion angulate. 



Orange, multi- 

 plicate, abnormally 

 thick, outer margin 



at the insertion 

 producted upwards. 



Imperfect as this comparison from mere diagnosis must necessarily 

 be, it seems to entitle the Perak shell to specific distinction. 



56. Mr. de Morgan mentions (1. c, p. 70) a second species, H. jous- 

 seaumei, de Morg., from the Pluss valley, which is said to differ from 

 H. elephas by the much smaller size, the white colour, the greater size 

 of the last whorl at its beginning, the penultimate whorl having a 

 rather prominent gibbosity at the right side, the flattening of the last 

 whorl being more distinct, the margination of the sutui'e deeper im- 

 pressed, the narrower umbilicus, and the less reflected peristome. The 

 41 



