396 CEYLON PEARL OYSTER REPORT. 



emphasise particularly (1) above, together with the condition of the walking legs, and 



for the present consider this form a variety of Z. gemmula. 



I may note that 2M is completely divided into two by a longitudinal groove both 



in de Man's Z. gemmula and in the new variety, while Dana describes it as only 



partly divided. Another point is that in the present specimens the hollowing of the 



finger tips is not obvious; I should describe the fingers as blunt merely, de Man's 



figure indeed represents them very well. A point in the present specimens not 



mentioned by de Man is the presence of a curious little tuft of brown hair (seen well 



with a lens) which rises from a groove running along the inner surface of the fixed 



finger. 



(a) adult J . (b) young J . de Man's J . (c) adult ? . de Man's ? . 



C.l . 7-25 5-50 14-25 6"25 10-00 



C.b.-r-C.l 1-48 1-45 1-47 1'48 1*53 



Fronto-orbitalb.-r-C.l. 0'93 l'OO (CHI l'OO 0'90 



Deinania, n. gen. 



Carapace pentagonal, moderately convex antero-posteriorly. flattened from side to 

 side in its posterior half; the regions well delimited and subdivided into numerous 

 lobules, the surface of which is smooth. The antero-lateral borders are blunt, cut by 

 shallow grooves into four lobes ; the border is faintly continued below the eye to the 

 antero-lateral angle of the buccal cavern ; the posterolateral borders are straight and 

 strongly convergent. 



Front prominently bilobed, its breadth about one-third the greatest carapace- 

 breadth, its plane is a continuance of the postero-anterior curve of the dorsum of the 

 carapace. Orbits large, the three suture lines near the outer angles distinct : eyes on 

 short thick stalks. 



The anteunules fold in a transversely oblique direction, making an angle of 40 

 (approximately) with a transverse line ; the inter-antennulary septum is broad. Basal 

 joint of antenna not quite as long as the posterior border of one of the antennulary 

 fossae ; as a whole it stops short of the orbital hiatus, but its antero-external angle is 

 produced into the latter ; its autero-internal angle touches a downward projection of 

 the front ; the flagellum is short (less than major diameter of orbit), lodged in the 

 orbital hiatus. 



No ridges define efferent branchial channels in anterior portion of buccal cavern. 



Merus of external maxillipeds pointed anteriorly, its borders sloping obliquely 

 backwards, making together an angle of 90 (approximately). Chelipeds equal in 

 female (male not known) : lingers not hollowed at tips. Walking legs with the 

 upper border of the merus, carpus and propus and the lower border of merus and 

 propus cristate. 



Abdomen of male not known. 



Carapace length (including rostral lobes) of only specimen known is 32'50 millims. 



