190 A. Alcock — Carcinological Fauna of India. [No. 1, 



Sub-family VI. Pilumnim. 



Alliance I. Pilumnoida. 

 Pilumnus. Actumnus. 



Pilumnus, Leach. 



Pilumnus, Leach, Trans. Linn. Soc. XL 1815, p. 321 ; and Malac, Podophth. 

 Brit.: Latreille, Encycl. Meth. X. p. 124: Desmarest, Consid. Gen. Crwst. p. Ill : 

 De Haan, Faun. Japon. Crust, p. 19: Milne Edwards, Hist. Nat. Crust. I. 415: 

 Dana, Silliman's Amer. Journ. Sci. and Arts, (2) XII. 1851, p. 127, and U. S. Expt. 

 Exp. Crust, p. 229 : Milne Edwards, Ann. Sci. Nat. Zool. (4) XX. 1863, p. 285 : 

 Kossmann, Eeise roth. Meer. p. 37 : Milne Edwards, Miss. Sci. Mex. Crust, p. 280 : 

 Miers, Challenger Brachyura, p. 145. 



In the numerous species of this genus the carapace and legs are 

 generally thickly covered with hair. 



Carapace transversely oval or subquadrilateral, declivous anteriorly ? 

 flat posteriorly, not greatly broader than long ; the regions, as a rule, 

 but moderately plainly demarcated and areolated. 



Antero-lateral borders not longer, but commonly shorter, than the 

 postero-lateral, and cut into teeth which, very commonly, are spiniform. 



The front is usually about a third the greatest breadth of the cara- 

 pace, but is sometimes broader : it is cut into two lobes, the outer angle 

 of each of which commonly forms an independent dentiform or spini- 

 form lobule separated from the supra-orbital angle by a groove or notch. 



The orbits generally have a gap or fissure jnst below the outer 

 angle, and one or two gaps or notches in the upper border: the inner 

 lower orbital angle is commonly sharp and prominent. The eyestalks 

 are moderately long and slender. 



The antennules fold transversely. The basal antennal joint is 

 short, either not quite touching the front, or just touching it by its 

 inner angle ; the flagellum, which is planted in the orbital hiatus, is 

 long, usually very much more than the major diameter of the orbit. 



The ridges of the endostome, defining the expiratory channels, are 

 usually plain but not very high : the anterior border of the merus of the 

 external maxillipeds is almost transverse and is not notched. 



The chelipeds are stout, the fingers coarse, short and pointed. 

 Legs usually stout and of moderate length. 



The abdomen of the male consists of seven separate segments. 



Key to the Indian species of Pilumnus. 

 1. Abnormal species : — 



Carapace and chelipeds quite smooth and devoid of hair P. Isevis. 



Carapace covered with symmetrically disposed, raised, 



curved or sinuated ridges , P. lalyrinthicn*. 



