DECAPODA. BRACHYURA. 



545 



ance with their environment, and a crab dressed in algae has been observed 

 to pick them off when placed in an aquarium with sponges, replacing them 

 with portions of the latter (Graeffe, Eisig, Sluiter, Robertson, Aurivillius). 



I. Basal antennal segment well developed, usually occupying a great 

 part of the infra-ocular space. 



Fam. 1. Inachidae. Eyes not retractile, or retractile against the sides 

 of the carapace ; orbits in general not defined. Rostrum simple or 

 bifid, walking legs sometimes very long. Macropodia Leach ( = Steno- 

 rhynchus Lam.) Spider Crab. M. rostratus (L.) and M. longirostris (Fabr.) 



FIG. 330. a, Zoaea of Inachus in advanced stage with rudiments of the third maxilliped 

 (Kf") and the five pairs of ambulatory feet (5Bp) ; C heart ; L liver, b, Megalopa stage of 

 Portunus ; Ab abdomen. F' to Fv first to fifth ambulatory legs. 



are common in depths of a few fathoms round our coasts. Achaeiis Leach. 

 A. Cranchii Leach. British. Inachus Fabr., cephalothorax triangular, 

 spiny, rostrum short, chelipeds much shorter than the succeeding pair 

 of legs. In this, as in other genera which are infested with parasitic 

 Crustacea (Isopods, Cirripeds, etc.) the males so circumstanced may 

 assume hermaphrodite characters (see p. 415). /. dorsettensia (Penn.), 

 /. dorynchus Leach and /. leptochirus Leach, are British. Lepto- 

 podia Leach, rostrum not bifid, but long and serrated. Macrocheira 

 de Haan. M. Kdmpferi de Haan has a span of 8-11 feet. Huenia 

 de Haan. Lispognathua A. M. Edw. L. thomsoni (Norman) widely dis- 

 tributed, has been taken at depths down to 600 faths. Ergosticus A. 

 M.-Edw. Platymaict, Cyrtomaia and Echinoplax Miers. Euprognatha 

 Stimpson. 



Fam. 2. Maiidae. Eyes retractile within orbits, whose margins are 

 fissured. Maia, Lam. cephalothorax round-ovoid, with projecting deeply 

 cleft rostrum ; basal joint of 2nd antenna with 2 long spines. M. squinado 

 Herbst, legs rather short, shell spiny. Mediterranean, extends to S. 

 coast of England. M. verrucosa M.-Edw. Hyas Leach, cephalothorax 

 oval, somewhat flattened, with pointed rostrum and without a preorbital 

 spine. H. araneus (L.) and H. coarctatus Leach. British. Chorinus Latr 

 Z III N N 



