Decapod Crustacea of Bermuda, Part II. 89 



He divided the genus into six groups of species. Of these two, 

 viz., the Comatuktrum-gTOUp and the Biun^nicnlat its-group have 

 not been found at the Bermudas, nor in the West Indies ; accord- 

 ing to him they are entirely oriental. 



De Man, op. cit., 1911, recognized 62 species of the genus and 

 15 named varieties from the Indo^ Pacific seas. At least seven 

 species occur at the Bermudas. 



In many cases the described differences are slight and may be 

 due partly to individual or local variations, or to hybridism. The 

 Rev. Thomas R. R. Stebbing, in a somewhat jocular way, says 

 that "in the discrimination of these species minute measurement 

 plays an almost alarming part, because, as the eyes are completely 

 covered by the carapace, the vision of these creatures must be 

 dim. and without compasses the members of different species will 

 never know one another apart. Perhaps, indeed, the numerous 

 varieties may be the result of inconsiderate intermarriages." 



It is at any rate a group in which variations and perhaps 

 "mutations" are abundant and in which natural selection has served 

 to adapt the various species to varied and often unusual conditions 

 of existence. Most of them seem to be admirably protected by 

 their habits, colors, etc., so that they are often very numerous in 

 individuals, as well as in species and varieties. 



Analytical Table of the Bermuda species and of some additional related 

 North American and West Indian species of Synalpheus. 



A. Rostrum slender, spiniform, with no vertical prolongation. Ocular 

 spines longer than wide. Hooks of dactyl of third to fifth feet dis- 

 similar, unequal in width and form, lower one the wider and stronger, 

 strongly divergent at a wide angle to axis of dactyl ; .usually a small 

 spur or prominence proximal to lower hook. Merus often spinose. 



Neomeris-group. 



b. Ventral spur of dactyl of third to fifth feet prominent, spur-like ; inner 

 hook abruptly divergent, bicurved 6". hemphilli. 



c. Antennal spine equal to carpocerite var. hemphilli. 



cc. Antennal spine longer than carpocerite var. longicornis. 



bb. Ventral spur of dactyls low, obtuse or obscure; legs slender; merus 

 of third pair of legs four times as long as wide ; antennal scale or 

 scaphocerite equal to or exceeding the stalk 5". fritsmulleri. 



AA Hooks of dactyls of third to fifth feet nearly or quite equal in 

 width at base ; merus generally without spines. 



B. Dactyls long and slender ; the hooks directed in same line with the 

 dactyl, little curved, the upper one the longer. Scale of scaphocerite 



