122 THE VOYAGE OF H.M.S. CHALLENGER. 



species beyond certain depths, wherever a Globigerina bottom is to be found, a circumstance 

 that is suggestive of the idea that in natural selection the character of the food is one of 

 the most permanent influences in their geographical distribution. 



Eryoneicus, Spence Bate. 



Eryoneicus, Sp. B., Ann. and Mag. Nat. Hist., ser. 5, vol. x. p. 457, December 1882. 



Carapace globose, dorsally hemispherical, nearly as broad as long : pleon narrow 

 and folded beneath the pereion : rhipidura well-developed : telson as long as the lateral 

 plates : ophthalmopoda absent. 



First pair of antennae having the first joint of the peduncle cylindrical, like the second 

 and third, which terminates in two flagella. 



The second pair of antennae is scarcely longer than the first and carries a small 

 scaphocerite and a long phymacerite. 



The first pair of pereiopoda is long, and terminates in a narrow and slender chela ; the 

 second and following pairs are successively shorter and are chelate, except the last, which 

 terminates in a short and simple dactylos. 



Eryoneicus csecus, Spence Bate (PI. XIIe). 



Eryoneicus cxeus, Sp. B., Ann. and Mag. Nat. Hist., ser. 5, vol. s. p. 457. 



Carapace orbicular and circular, dorsally and laterally armed with numerous long, 

 slender, spine-like teeth that appear to be symmetrically arranged on each side of the 

 median line, the smaller being anterior and the larger posterior ; the largest are situated 

 near the postero-external angles of the carapace, the lateral walls of which are inflected 

 on the ventral aspect from the frontal to the posterior margins. 



The pleon is narrow, being about one-fifth the diameter of the carapace, and is simi- 

 larly furnished dorsally as far as the extremity of the telson with long and slender 

 spine-hke teeth. 



The ophthalmopoda are absent. 



The first pair of antennae has the flagella unequal. 



The second pair is not much longer than the first ; it carries a small scaphocerite and 

 a long, straight, cylindrical phymacerite. 



The second pair of gnathopoda is pediform, moderately long and slender. 



The first pair of pereiopoda is smooth, long and slender, the chela being scarcely 

 broader than the meros ; the second pair is short, slender and armed with a few long 

 spines ; the third and fourth are shorter and furnished with a few corresponding hairs ; 

 the fifth is still shorter and terminates in a short and simple dactylos. 



The anterior or first pair of pleopoda is wanting, and the others are biramose and 

 foliaceous. 



