1919-] N. Annandale & B. Prashad : Fauna of Yunnan. 419 



The head is distinctly spindle-shaped, bluntly pointed in front 

 and tapering to a short contracted neck behind. The snout is of 

 moderate length. The mouth is a longitudinal slit, entirely ven- 

 tral in position except when the head is much contracted, with 

 tumid, corrugated lips The tentacles are rather stout but taper 

 to their apex. They are situated rather far back on the head. 

 The eyes are very large and prominent, though sessile. They 

 seem to have a peculiar construction, being covered with integu- 

 ment except for a minute pinhole in the centre. The retinal cup 

 is relatively large, deeply pigmented and of an oval shape. The 

 situation of the eyes is peculiar, for they are situated one at the 

 base of each tentacle just behind the point at which it diverges 

 from the head. 



The edge of the mantle is smooth and pale, the remainder 

 being deeply stained with black pigment. The mantle is ample 

 and its margin is free all along the outer end of the branchial 

 chamber, which is relatively large. The gill consists of numerous 

 narrow but rather deep ridges, which run almost completely 

 across the roof of the chamber and are not differentiated at either 

 extremity. The osphradium is well developed and ridge-like. 



The mouth opens into a short conical muscular pharynx, 

 which is rather shorter than the buccal mass. The muscles of this 

 mass are large and powerful, forming a well developed bulb. The 

 horny lateral jaws are situated inside these muscles, forming in 

 contraction a thin longitudinal plate at either side of the radula. 

 They are merely cornified and pigmented patches on the sides of 

 the alimentary canal, with ill- defined outlines and with an obscure- 

 ly squamous structure. The radula is narrow and of moderate 

 length. The central tooth is relatively large and of transverse 

 form. Its lower margin is sinuous and its lower lateral angles are 

 pointed. The cusp is broadly rounded at the tip, considerably 

 narrower and shorter than the disk. There are three latero-basal 

 denticulations on each side, each pedunculate. The lateral tooth 

 IS hardly at all bent but consists of a relatively narrow slanting 

 basal part and a broad upper part bearing a broad, downwardly 

 directed lobe on its disk. The m?in denticulation is triangular, 

 but rather bluntly pointed. It occupies rather less than a third of 

 the free margin and has two or three small denticulations on either 

 side. The inner marginal tooth is not much broader than the outer 

 and has its denticulation, of which there are a considerable number, 

 smaller and sharper. Neither marginal is much narrower below 

 than above, both begin to taper a short distance above the base. 

 The outer marginal has an elongate triangular membrane on its 

 outer margin. The oesophagous is rather long, narrow, cylindrical 

 and sinuate. The salivary glands, situated at the posterior end 

 of the buccal mass, are small and their ducts short. We have not 

 been able to trace the ahmentary canal further inwards. The 

 intestine is a relatively capacious tube which opens by a simple 

 pore on the edge of the mantle on the right side, running along 

 the outer edge of the branchial cavity. The faecal pellets it 



