1899.] A. Alcoek — Carcinoloyical Fauna of India. 29 



Neptunus, Achelous, Amphitrite, Pontus, Be Haan, Faun. Japon. Crust, pp. 

 7, 8, 9. 



Posidon, Herklots, Add. Faun. Carcin. Afric. Occ. p. 3. 



Lupa, Arenaeus, Amphitrite, Dana, U. S. Expl. Exp. Crust, pt. I. pp. 270, 275, 

 289. 



Euctenota, Gerstaecker, Archiv. f. Naturges. XXII. 1856, i. p. 131. 



Neptunus, Achelous, A. Milne Edwards opo. cit. 



Callinectes, Stimpson, Ann. Lye. Nat. Hist. New York, VII. 1860, p. 220. 



Xiphonectes, A. Milne Edwards, Nouv. Archiv. du Mus. IX. 1873, p. 157. 



Hellenus, A. Milne Edwards, Miss. Sci. Max., Crust, pp. 210, 221. 



Neptunus, Xiphonectes, Miers, Challenger Brachyura, pp. 171, 183. 



Portunus, M. J. Rathbun, see Proc. Biol. Soc. Washington, June, 1897, pp. 155, 

 160. 



Carapace usually transverse, broad, and depressed or little convex, 

 often with the surface areolated. 



Front proper well delimited from the inner supra-orbital angles 

 and cut into from 3 to 6 — usually /ow — teeth : its breadth (not includ- 

 ing the supra-orbital angles) is from a sixth to a fifth the greatest 

 breadth of the carapace (lateral epibranchial spines not included), and 

 it is often somewhat receding. 



Antero-lateral borders oblique, arched, longer than the postero- 

 lateral, cut into 9 regular teeth ( including the outer orbital angle) of 

 which the 9th may be enlarged or not. 



The orbit usually has 2 fissures or sutures in the upper border, 

 which border is less prominent than the lower border, so that the orbit 

 very often has a dorsal inclination : the lower border has a fissure or 

 suture near the outer angle, and the inner angle is dentiform and usually 

 very prominent. The antennules fold transversely. 



The basal antenna-joint is peculiarly short and has its antero- 

 external angle produced to form a lobule or spine extending into the 

 orbit : the flagellum, which is of fair length, stands in the orbital hiatus^ 



Epistome short or even linear, sometimes prolonged in the middle 

 line to form a spine lying below the inter-antennuiary septum. Buccal 

 cavern squarish, broader than long, the efferent branchial channels 

 almost always very well defined. 



Chelipeds longer, usually much longer, than any of the legs, and 

 massive : arm with spines, both inner and outer angles of wrist spini- 

 form, palm prismatic costate and usually with spines, fingers usually 

 nearly as long as the palm and strongly toothed. 



Legs compressed : in the last pair the merus and carpus are short 

 and broad, and the propodite and dactylus are typically foliaceous and 

 paddle-like for swimming. 



The abdomen of tlie male is five-jointed, the 3rd-5th terga being 

 fused : the ] st tergum in both sexes is almost entirely concealed beneath 

 the carapace. 



