162 
A. Alcook —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 merus 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 Ste?iocionopoida , 
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 Criocarcinus 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 references 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. Inachinde. 
Alliance i. Leptopodioida. 
* Achseus. 
Achseopsis, Stimpson, Proc. Ac. Nat. Sci. Philad., 1857, p. 219. 
? Anisonotusy A. Milne-Edwards, Miss. Sci. Mex. Crust. I. p. 195. 
* Camposcia, 
