365 



DESCRIPTIONS OP THE ANIMALS OF TWO LAND SHELLS FROM 

 PERAK. "SKEAT EXPEDITION IN THE MALAY PENINSULA, 

 1899-1900." 



By Lieut. -Colonel H. H. Godwin- Attsten, F.R.S. 



Bead \4:th May, 1909. 



Plate XV. 



1. Leptodontaeion Perakensis, n.sp. PI. XV, Figs. \-\d. 



Hah. — Talum, Perak ; " Skeat Expedition," in Brit. Mus. Collection. 



Shell very globose, thin, and membranaceous ; spire low, apex 

 rounded; peristome somewhat sinuate ; suture moderately impressed ; 

 no sculpture, smooth, shiny ; colour ochraceous green ; whorls 3-^- ; 

 aperture and columellar margin not seen. Only one specimen 

 received, and to examine the animal the shell was broken to extract 

 it. Major diam. 6-3 mm. ; diam. of shell figured 5-5 mm. (Figs. 1, Iff). 

 Animal (Figs. 1^, \c, \d) pale-coloured throughout, without markings 

 of anj^kind. The right shell lobe in figure (Ic) is shown rolled up by 

 contraction in the spirit ; it is long, fairly wide, of even breadth at first, 

 then naiTowing, and in life would cover the portion of the shell below 

 and on side of the periphery. The young specimen from the Cam- 

 bridge Museum, a good deal contracted by the spirit, shows the right 

 shell lobe unfolded (Fig. Ih). There is a very small left shell lobe. 

 The right dorsal lobe is large and triangular, the left dorsal lobe in 

 two distinct lappets. The foot is pointed and has a long overhanging 

 lobe. The peripodial grooves are well marked, sole indistinctly divided. 

 Length of the animal about 16 mm. 



The jaw (Fig. 2, line block) is nearly straight, narrow, the cutting- 

 edge slightly concave; it is thin and transparent, arched above, 

 merging into the muscular tissue. 



The radula (Fig. 1, line block) consists of numerous rows of similar 

 curved teeth having a great number in a row, on long narrow plates. 

 The centre tooth is unicuspid, very long and pointed, the base 

 gradually widening out. All the admedians are nearly evenly 

 bicuspid, the outer cusp being very slightly the longer. 



The genitalia (Fig. 4, line block) were not got out quite perfect. 

 An araatorial organ with a blunt point is present, also a short ovoid 

 spermatheca with club-like free end ; the penis was broken off. 



This species has most interesting similarity to Leptodontarion 

 Hiraseaniis from Formosa, both in the jaw and radula and outward 

 form, even to the globose shape of the shell, but Hiraseanun is even 

 more globose. The generative organs differ in the presence of the 

 amatorial organ and in other details. Its relationship is therefore 

 closer with the Indian species, Z. minuta of Assam, as might be 

 expected, than with the Formosan form. 



This mollusc, one of seven, had been presented to the Natural 

 History Museum by Messrs. Annandale and Bobinson in May, 1904, for 



