162 A. Alcoek — Carcinological Fauna of India. [No. 2, 



joint is broad, and either has, or has not, one or both of its anterior 

 angles armed with a strong spine. The nierus of the external maxil- 

 lipeds usually has its antero-external angle strongly dilated ; and the 

 buccal frame is often much wider in front than behind. 



Alliance 3. Periceroida. The carapace is broadened anteriorly by 

 the outstanding, often tubular, orbits : the orbits are formed (1) by an 

 arched supra-ocular hood, or semi-tubular horn, (2) by a hollowed 

 post-ocular process, and (3) by a remarkable broadening, or by a pro- 

 longation, of the anterior part of the basal antennal joint ; and they 

 afford complete concealment to the retracted eye. The rostrum is often 

 more or less deflexed. 



I am afraid that this last sub-family will, at first, meet with hostile 

 criticism ; but I feel pretty sure that it is a natural group. For, taking 

 the nature of the orbits, eyes, and basal antennal joint as the primary 

 bond of relation, we find, if we exclude the aberrant Stenocionopoida, 

 a regular gradation from the imperfect orbit and the narrower basal 

 antennal joint of Maia, through the more perfect orbit and broader 

 basal antennal joint of, e.g., Micippa thalia and Micippa cristata, to the 

 perfect tubular orbit of Microphrys (if Microphrys cornutus be the type), 

 Tiarinia and Macrocoeloma. The Stenocionopoida again are linked on, 

 through Picrocerus and Picroceroides, to the Periceroida ; and, on the 

 other hand, through Criocarcifius to the Maioid Chlorinoides. 



The following is a list of the genera of Maioid Crabs, so far as 

 known to me, arranged in accordance with the afore-proposed classifi- 

 cation. Within each sub-family the genera are arranged alphabeti- 

 cally. Indian genera are printed in roman type, and all genera known 

 to me by autopsy are marked with an asterisk. 



Complete references are not given ; but only inferences to the 

 best diagnoses with which I am acquainted. The bibliography of 

 Indian genera will be found in the sequel. 



Family Maiidae. 



Sub-family I. Inachinse. 

 Alliance i. Leptopodioida. 



* Achaeus. 



Achseopsis, Stimpson, Proc. Ac. Nat. Sci. Philad., 1857, p. 219. 

 ? Anisonotus, A. Milne-Edwards, Miss. Sci. Mex. Crust. I. p. 195. 



* Camposcia. 



