24 ENDODONTICS. 



41. Philalanka depressa, Preston. 



Microcustis thivaitesi, var. depressa, Preston, Rec. Iiid. Mu^. iii, 

 1909, p. 135, pi. 22, fig. 6. 



Shell depressed-conoid, almost lenticular, pale corneous, trans- 

 lucent, shining, very finely striated and with excessively minute 

 spirals ; spire much depressed, suture deep. Whorls 4^, strongly 

 convex, closely wound. Aperture vertical, reniform ; peristome 

 acute, upper margin ascending at first, outer and basal evenly 

 arcu:ite, cokimeliar slightly dilated, vertical, 



Diam. 3"5, alt. 2 mm. 



Bah. Ceylon: Uda Pussellavva (F>'<;«^o;i). 



Mr. Preston considers this form a variety of thivaitesi, stating 

 that, except in the depressed spire, it appears to be normal. The 

 figure certainly bears out this view, but it must ha\e been very 

 badly drawn. A specimen, received by me from the authoi-, 

 differs from thivaitesi in several important respects, and the fore- 

 going description has been drawn up from it. The shell is much 

 more depressed, being almost lenticular ; the whorls are much 

 more convex above, the umbilicus is much wider, distinctly showing 

 all the whorls ; on the other hand, the region round the umbilicus 

 is not excavated as in thivaitesi, and the mouth is also different, 

 being reniform, not lunate. The whole shell has, in fact, a totally 

 different aspect, and I have no hesitation in according it specific 

 rank. 



42. Philalanka circumsculpta, Si/l-es. 



Microcytitis thwnitesi (non PfeiU'er), Jousseaume, Mt*m. See. Zool. 



France, vii, 1894, p. 272. 

 Macrochlaniys ? cirvumsculpta, Svkes, Proc. Malac. Soc. London, ii, 



1897, p. 2'3r>, pi. 1(), figs. 3 & 4 ; op. cit. iii, 1898, p. 65. 

 Philalanka circumsculpta, Godwin -Austen, Moll. Ind. ii, 1907, 



p. 194. 



Original description : — " Testa perforata, convexo - depressa, 

 nitida, cereo-hyalina ; spira breviter conoidea, apice obtusa ; 

 sutura impressa; anfr. 5, convexi, arteconvoluti, obsolete spiraliter 

 lirati, ullimus non descendens, basi inflatus; apertura lunaris ; 

 peristoma rectum, acutum, niai-gine columellari ad perforationem 

 dilatato, subrefiexo. 



" JJiam. max. 5, min. 4-7 n)m. ; alt. 3 mm.'' (fSi/l-cs.) 



Bab. Ceylon: Wataw ida ( CoUett) ; Nuwara-Eliya (/SVmo/;). 



" This species is nearly related to the Belix thivaitesi of Pfeift'er 

 (which is also obsoletely spirally lirate), but may be at once dis- 

 tinguished by the fact that its breadth is greater in proportion to 

 the number of whorls. The umbilicus is also slightly smaller in 

 the present species, the spire is not so much raised in proportion, 

 and the nucleus is larger. The sculpture is stronger than in 

 B. thivaitesi, and a few of the stronger lines of growth intersect 

 the revolving lirae, thus giving the shell a decussated appearance 

 under a lens." 



