Carcinologlcal Fauna of India. 215 



46. Leucosia unidentata, De Haan. 



Leucosia unidentata, DeHaan, Faun. Japon., Crust., p. 133, pi. xxxiii, fig. 3 : Bell, 

 Trans. Linn. Soc. Vol. XXI. 1855, p. 284, and Cat. Leucos. Brit. Mus. p. 6: Easwell, 

 P. L. S., N. S. Wales, Vol. IV. 1879, p. 44, and Cat. Austral. Crust, p. 118. 



Leucosia obtusifrons var. unidentata, Ortmann, Zool. Jahrbucher, Sj'st. etc., VI. 

 1892, p. 585. 



Carapace bluntly hexagonal or subcircular, about nine-ten! hs as 

 long as broad : its surface perfectly smooth and devoid of hair : its antero- 

 lateral borders sinuous, convex, faintly beaded anteriorly, strongly 

 beaded posteriorly : its true postero-lateral border distinctly beaded or 

 crenulate up to the level of the base of the last pair of legs : its thick- 

 ened milled epimeral edge, which is continuous with the posterior 

 margin and ends at a sharp tooth just behind the base of the chelipeds, 

 is not visible, dorsally, when the carapace is held, without any inclina- 

 tion, straight in front of the observer's eyes : its posterior margin short, 

 gently curved, finely beaded, with the deflexed surface below it quite 

 smooth. 



The puckered mouth of the pterygostomian invagination — the 

 thoracic sinus of Bell and subsequent authors — shows as a roughly 

 9-shaped loop of equal-sized large pearly granules situated between 

 the base of the chelipeds and the strongly-pronounced lateral angle, or 

 eave, of the carapace : the pterygostomian plate is deeply indented, 

 transversely, in front of this loop of granules. 



The convexities of the hepatic regions are an almost indistinguish- 

 able part of the general convexity of the carapace. 



The front is prominent, dorsally convex, and truncate-triangular ; 

 its length is less than its breadth ; its front edge is strongly deflexed 

 and very faintly trilobed, the middle lobe being mucronate. 



The ventral surface of the ischium of the external maxillipeds in 

 the female, as in the male, is flat and smooth. 



The chelipeds in the adult male are considerably more than half 

 again as long as the carapace. The upper surface of the arm has two 

 divergent longitudinal rows of pearly tubercles in addition to those 

 that bound its inner and outer borders: these two rows start from a 

 basal eminence formed of 7 or 8 smaller coalescent tubercles, and end 

 near the distal quarter of the arm. The inner surface of the arm is 

 completely covered with pearly tubercles of unequal size : the under 

 surface is smooth except in its basal third, or half. The wrist is smooth 

 except for two lines of bead-like granules bounding its inner surface, — 

 one line dorsal in position, the other ventral. The hand and fingers 

 together are as long as the arm. The hand is half again as long as 

 broad, its narrow inner surface bears several rows of small bead-like 

 granules the upper and lower of which are sharply defined and converge 



220 



