BULLEN : SUMATRAN LAND AND FKESH-WATEK MOLLUSCA. 



127 



11, Clausilia Sumatrana, Martens; and 12, C. robustior, n.sp. 



Dr. E. von Martens' described two forms of his Clausilia Sumatrana, 

 which he termed var. a and var. b. He did not, however, give them 

 the varietal names, attenuata and hrevior, as stated by Mr. Sykes,'^ 

 those being merely the first words of the descriptions respectively. 

 I have never seen such a large specimen (31Jmm. in length) of the 

 var. a, as described by Martens, the largest example that has come 

 under my notice being only 30 mm. long, the actual length of 

 Martens' figure. When placed side by side with the var. b (hereafter 

 named rohistior) I cannot believe that they belong to the same species, 

 the form is so very unlike, and the number of whorls is constantly 

 different, judging from the specimens examined. The large example 

 above referred to, from Mount Sago, has 11 J whorls, which are 

 peculiar on account of their exceptional flatness. This, however, 

 may partly be due to attrition. It also presents a very remarkable 



abnormality of the peristome in the form of a loop at the termination 

 of the lamella superior. This irregularity of growth is doubtless due 

 to an accident, as evidences of a fracture of the lip at this point are 

 observable. It is, however, so very peculiar that I have thought it 

 worth figuring. The sculpture of the body-whorl, which is only 

 slightly worn, is not quite similar to that of the short form (var. b), 

 being a trifle coarser, but the 5 plicae suturales, which vary in number 

 from 5-7 in the short variety, are of the same character exactly. 



Three other examples of this species from Loeboek Bangko are 

 intermediate in size between vars. a and h, being 25 mm. in length, 

 and consist of 10-10^ whorls. Thej^ are conspicuously more slender 

 than var. b (robustior) and the spire more tapering, but in sculpture 

 and with regard to the plicae they are almost similar, the former, 

 however, being coarser, as in the large abnormal specimen from 

 Mount Sago. 



1 Preuss. Exped. Ost-Asien, Zool., vol. ii, p. 379, pi. xxii, figs. 17-1 7c. 



2 Proc. Malac. Soc, vol. i, p. 28. 



