IS96.] A. Alcock — Carcinological Fauna of India. 137 



of the third pair of legs. The sternum is broad anteriorly, very narrow 

 or linear posteriorly. The afferent branchial openings are not found in 

 front of the bases of the chelipeds, and afferent currents probably reach 

 the branchial chamber between the posterior border of the carapace and 

 the bases of the last pair of legs. The external maxillipeds completely 

 cover the buccal cavern, and their palp is concealed in repose : their 

 exopodite is but little longer than the ischium. The branchiae are less 

 than nine in number on either side. 



Family CALAPPID^E. 



Calappiens, Milne-Edwards, Hist. Nat. Crust. II. 100. 

 Calappidea and Matutoidea, De Haan, Faun. Japon. Crust, pp. 124, 126. 

 Calappidss and Matutidse, Dana, U. S. Expl. Exp., Crust. I. pp. 390, 391. 

 Calappidse and Matutidse, Miers, 'Challenger' Brachyura, pp. 282, 293; 



Carapace more or less oval or subcircular, commonly with either 

 (J) a single denticle or a heavy spine at the junction of the antero- 

 lateral and postero-lateral borders, or (2) a postero-lateral vault-like 

 expansion over the ambulatory legs (Calappa). Front generally about 

 as wide as the orbit. The antennules generally fold obliquely. The 

 antennae are generally small. 



The external maxillipeds may (Matutinse) or may not {Galappinse) 

 completely close the buccal cavern, and their palp may {Matutinse) or 

 may not (Galappinse) be concealed in repose. 



The efferent branchial channels together form a deep channel in the 

 endostome the channel being covered in below by a long lamellar process 

 of the internal (first) maxillipeds. The afferent branchial openings 

 have the normal position in front of the bases of the chelipeds. 



The chelipeds are ponderous and greatly enlarged, and are practi- 

 cally symmetrical (except sometimes as to the fingers) * : the hands 

 especially are of great size — forming often the most conspicuous part 

 of the chelipeds, and are so curved as to shut closely against the ptery- 

 gostomian regions of the carapace, thus acting as a sort of buckler. 



The abdomen usually (always in Indian forms) consists in the 

 adult male of 5 segments, the 3rd-5th terga being fused together, and 

 of 7 separate segments in the female (and young male). The branchiae 

 in all Indian forms are nine in number on either side. 



In the male the vasa deferentia perforate the bases of the fifth pair 

 of legs. 



In the following list of genera belonging to the family Calappidse 



* In the exotic genus Platymera one cheliped is larger than the other. 



J. ii. 18 



