330 



A. E. Yen-ill Decapod Cruxtact'it of Ili-nn udn. 



form, are even less granulate*!.* Indeed, tin- latter arc scarcely more 

 granulated than the ordinary form of /,'/V,</v//. 



However, the front of AS. cincrta is narrower and more arched than 

 in - s '. A'/Vn/v// ; its lower margin is less sinuous, narrows more i.. \\aid 

 the ends, and is less turned up at the ed-e. so lhat it is less eoneaxc 

 aliove. The orbital notch is not so deep. Still these differences .-m- 

 lut slight. The carapace seems to lie slightly less convex. The 

 chehe are essentially the same in both, and the carpal joint is 

 roughened in the same way. The incrus joints of tlie pereiop.ids 

 are about equally flattened in both; the lirush of hairs mi I lie under 



Figure 8. 



cinerea (t'r<>m Florida i. slightly enlarged. Phot. A. II. 



side of the- last two joints is nearly 1 he same in both, though per- 

 haps a little smaller, and with shorter hairs in & cinerea. The 

 differences are s,> slight that it seems not improbable that >'. cinerea 

 is another semiterrestrial race or subspecies that has been derived 

 from S. Jft<-n,;//\ under a somewhat different environment. In fact, 

 all those species that live more or less on the drv land or in tree> 

 (e. g., S. ]!<>/ rti, an arboreal West Indian species) must have been 

 originally derived from amphibious or aquatic species, but the dif- 

 ferentiation has gone farther in some than in others. Doubtless they 

 all go into the sea to breed, and probably they all have similar zo"-a 

 and megalops larval stages. 



But in the case of the Bermuda forms, it is easv TO believe that 

 they have acquired different breeding habits or different breeding 



* In Miss Eathbun's analytical table of Sesarmce (Synopsis American Sesarmze, 

 Proc. Biolog. Soc. Washington, :;i. pp. 90, 91, 1897), the smoothness of the 

 suprafrontal lobes, "smooth or nearly so," is made a diagnostic character for S. 

 Bicordi, while S. cinerea is put in a group having the suprafrontal lobes 

 " tuberculate or granulate,'' and in a subgroup having them " faintly granulate." 

 The degree of granulation seems to be variable. 



