1074 MALAYSIAN LAND AND FRESHWATER MOLLUSCA, 
front above the mouth, whicli is sub-cii’cular and angular 
anteriorly in young specimens, which also present a little 
canaliculate prolongation, wdiich is obliterated little by little 
as the animal is developed, leaving when completely closed only 
tlie appearance of a triangular area traversed longitudinally by a 
linear scar, and lea\*ing in that state a rounded double peristome. 
Internal lip relatively less thick, deeper coloured, and more 
shining ; external reflected, but not always perfectly united with 
the inner. Operculum testaceous, somewhat thick, with a central 
nucleus, and composed of two plates ; external face multispiral, 
sliglitly concave in the middle ; internal face few whorls, also 
slightly concave in the middle ; margin with a feeble keel. 
The foot is not divided as in the Cyclostomidse, where there 
are two longitudinal parts independent of each other for crawling 
The animal is long, with a very thin mantle, whose anteiior 
border is simple and not papillose ; head and muzzle short, thick, 
the latter grooved transversely on its upper face ; buccal orifice, 
when open, oval, and showing the extremity of the raduhi, but 
Avhen the mouth is closed it is a simple slit ; tentacles short, 
thick, transversely striate, slightly constricted at the base, of a 
uniform reddish color ; eyes at the external base well pigmented 
and placed on short, obtuse, and slightly convex peduncles ; foot 
thick, fleshy, wide, short, oval, obtuse, truncate in front, round 
behind. There is a large pedal sinus in front, but no trace of 
that longitudinal division which is common in the family of 
Cyclostomidfe, but the foot is rather that of the family of 
Cyclophoridee. The upper part of the foot carries the operculum, 
the adherence of which is circular, with an umbilicated non- 
central projection, which corre.sponds to the nucleus of the 
internal face, so that half the organ is free, like the genus 
Cyclophoms. The sexes are distinct, the females being a little 
larger in size. The mouth has two mandibular plates, brown, 
chitinous, and solid, visible to the naked eye, but when magnified 
displaying a facetted structure roughly hexagonal or rounded. 
This may possibly be some arrangement connected with the eyes 
of the animal, or a facetted eye-structure like that which exists 
