238 



Carcinolugical Fauna of India. 



Alliance 3. Pericer- 

 oida. — Carapace- 

 usually broadened 

 anteriorly by the 

 outstanding or- 

 bits : the orbits 

 are either nearly 

 or quite complete 

 above and below, 

 being formed by 

 a strongly-arched 

 supra-ocular eave 

 in close contact 

 with an excavated 

 post-ocular lobe, 

 a process of the 

 basal antjenn al 

 joint filling in the 

 floor below. 



fl. Carapace oblong : rostrum broadly la- 

 minar, vertically or nearly vertically 

 deflexed : orbits complete, but shallow.. MiciPPA. Z^o 



2. Carapace subcylindrical, the rostrum 

 along with the front part of the gastric 

 region vertically deflexed 



Cyphocarcinus. 



■{ 3. Carapace more or 

 less pyi'iform : ros- 

 tral spines distinct 

 from the base, ho- 

 rizontal or slightly , 

 deflexed: orbits in \ 

 the form of out- 

 standing tubes 

 which completely 



^ ensheathe the eyes. ^ 



Rostral spines di- 

 vergent Macrocoeloma. 



Rostral spines 

 parallel and close- 

 ly approximated 

 throughout their 



extent Tiarinia. .15 1> 



Alliance I. Maioida. 



Maia (Lamk.) Edw. 



[Maia, Lamarck, Syst. Anim. sans verteb. V. 154 (partim)."] 



Maia, Latreille, Hist. Nat. Crust. VI. 87 (partim). 



Maia, Desmarest, Consid. Gen. Crust., p. 143. 



Maia, Milne-Edwards, Hist. Nat. Crust., I. 325. 



Maia, Miers, Journ. Linn. Soc, Zool., Yol. XIV. 1879, p. 655. 



Carapace pyriform, with the regions indistinct, the surface closely 

 granular or spinular, and the lateral borders usually armed with large 

 spines. The rostrum consists of two rather short, straight, divergent 

 spines. The basal joint of the antenna? is broad, and has both the antero- 

 external and antero-internal angle produced to form spines : the mobile 

 portion of the antenna, which appears to spring from within the orbit, 

 is completely exposed. The eye-stalks are long and curved, and bear 

 the cornea chiefly on their ventral surface. The orbit is formed by 

 a prominent supra-ocular eave which has its postero-external angle 

 produced, by a sharp post-ocular spine, and by another spine between 

 these two: the eyes are completely concealed from dorsal view when 

 retracted. The external maxillipeds have the merus as broad as the 

 ischium, the palp being attached to the antero-internal angle of the 

 merus. 



The chelipeds are slender, with cylindrical joints and styliform 

 fingers. The ambulatory legs decrease very gradually in length : the 

 first pair are not much longer than the carajDace and rostrum : the dac- 

 tyli of all are styliform. 



The abdomen in both sexes consists of seven distinct segments. 



84 



