104 Dr. W. T. Caiman on 



the full size or the definitive characters of the species. The 

 present collection includes a number of specimens exceeding 

 20 mm. and one which measures 24 mm. in Length of capi- 

 tulum, and these differ considerably in general appearance 

 from the small syntype. 



For comparison I have examined a considerable series of 

 Scalpellum squamuliferum from the Bay of Bengal, received 

 from the Indian Museum, and four specimens — determined 

 by Gruvel and mentioned by Annandale — stated to come from 

 Singapore. The results of this comparison, as regards the 

 hermaphrodite individuals, may be briefly stated as follows : — 



S. bengalense. Valves thinner, separated by distinct inter- 

 spaces, cuticular covering less opaque. Upper latus 

 with basal margin about as long as the scutal and two- 

 thirds or more of width of scutum, with scuto-tergal 

 angle less acute (75°-90°). Inframedian latus rhorn- 

 boidal, hardly wider than high. Rostrum straighter as 

 seen from side. Carina narrower, its width at base 

 less than one- sixth of its length. Peduncle much less 

 . strongly annulated, the ridges separated by narrow and 



shallow grooves. Scelerites of peduncle ovoid or pyri- 

 form nodules, rarely more than twice as long as wide, 

 arranged in oblique rows ascending from rostral to 

 carinal side of peduncle and more or less interrupted 

 on carinal side ; even in large specimens these rows, 

 Avhile less regular than in small specimens, are not alto- 

 gether masked by the transverse annulations. Dorsal 

 filamentary appendages usually three in number, 

 sometimes two, or [teste Annandale) absent. 



S. squamuliferum. Valves thicker, all in contact or nearly 

 so, cuticle more opaque. Upper latus with basal 

 margin one-half to two-thirds as long as scutal, and 

 more than one-half of width of scutum, with scuto- 

 tergal angle more acute (50°-65°). Inframedian latus 

 nearly triangular and about twice as wide as high. 

 Rostrum more curved. Carina wider, its width at base 

 more than one-fifth of its length. Peduncle strongly 

 annnlated, the ridges separated by deep grooves which, 

 in places, are wider than the ridges. Scelerites rod- 

 shaped, up to five times as long as thick, crowded 

 together on the ridges and absent from the furrows, so 

 that the arrangement in oblique rows seen in the 

 young is absent or obscured in large individuals ; the 



