182 HYPSELOSTOMA. 



Malay Peninsula: Biserat Caves, State of Jalor (Skeat 

 Exped.). 



Hypselostoma laidlawi COLLINGE, Journ. of Malacol., ix, 

 Sept. 29, 1902, p. 83, pi. 5, f. 29, 30. 



Prom the insufficient description and figure, the affinities 

 of this species cannot be determined. It is of about the size 

 of H. dayanum, but has fewer teeth parietal, columellar, 

 upper and lower palatal, according to the description. Noth- 

 ing is said of an angular lamella, which should be present if it 

 is related to the bensoniana group. Mr. Collinge's figures are 

 copied. I suspect that the artist slanted the sutures in the 

 wrong direction. The shell may be a Gyliauchen. 



Loochoo Species. 

 5. HYPSELOSTOMA INSULARUM Pilsbry. PL 32, figs. 1 to 4, 6. 



The shell is very small, conic, with wide, nearly flat base ; 

 thin, pale brown, dull and lusterless, faintly striate, and en- 

 circled with minute spiral striae. Whorls 4%, convex. The 

 penultimate whorl becomes flat in its last half. The last 

 whorl has a strong but not acute peripheral keel, which does 

 not reach to the aperture. Above the keel the whorl is flat- 

 tened and concave; below it is slightly convex. Near the 

 aperture the whorl is straightened, loses the keel and becomes 

 convex above and below, somewhat tubular. It ascends slowly. 

 The base is weakly convex with a minute central perforation 

 and a long, curved, umbilical suture. The aperture stands 

 free of the preceding whorl, and looks upward somewhat. It 

 is irregularly rounded. The peristome is continuous, free, 

 thin and expanded throughout. There are six teeth situated 

 deep in the throat, as follows: A high, compressed, deeply 

 entering angulo-parietal lamella, the angular portion of which 

 flares towards the periphery where it overrides the parietal 

 portion; a thin entering columellar lamella which curves 

 downward and descends slightly as it enters; a minute sub- 

 columellar lamella; a rather large upper palatal plica, and a 

 smaller, more deeply placed and basally situated lower palatal, 

 with a minute interpalatal plica between these two. 



Alt. 1.75, diam. 2.3 mm. 



