184 PROFESSOR CHARLES CHILTON ON THE 



First gnathopod (fig. 6) moderately stout ; basal joint stout, of equal width through- 

 out ; a few tufts of long setae near the distal end of its posterior margin ; ischium, merus, 

 and carpus all short, subequal, and all bearing long sette on the posterior margin ; 

 carpus also with tuft at the antero-distal angle ; propod at base as wide as the distal 

 end of the carpus, narrowing slightly distally ; anterior margin straight or slightly 

 curved, and with tufts of long setae ; posterior margin slightly concave distally, and 

 bearing numerous long setae in tufts ; the palm transverse, straight, defined by two 

 long spinules ; finger long, extending beyond the palm. 



Second gnathopod (fig. 7) slender; basal joint curved ; ischium much longer than 

 the merus ; carpus longer than the propod, which is narrowed at l)ase, slightly curved ; 

 palm rather short and slightly oblique ; the posterior margin of the merus is furred 

 and bears three tufts of long sette towards the distal end ; carpus furred on both 

 margins, with tufts of long setae on the lateral surface and anterior margin at distal 

 end, and several tufts, or short transverse rows, on the distal half of the posterior 

 margin ; propod with both margins furred, and tufts of long sette on their distal 

 portions, those on the anterior border towards the base of the finger forming a dense 

 group of very long setae. The first and second peraeopoda rather slender ; the merus 

 slightly broadened and produced at the antero-distal angle ; propod somewhat curved ; 

 finger about half as long as the propod, slender, curved, smooth. The third, fourth, 

 and fifth peneopoda are of increasing lengths, all having the merus much broadened 

 and produced, the propod curved, and the finger long, as in the first and second 

 peraeopoda ; basal joint of all expanded, that of the third rounded posteriorly, those of 

 the fourth and fifth somewhat angled below, and with the posterior margin convex 

 in its upper part and straight or slightly concave below, the hind margins feebly 

 crenulate. 



First uropods with the branches slender, subequal, longer than the peduncle, 

 marginal spines on the peduncle and on the outer branch. Third uropod witli peduncle 

 large, shorter than the branches, which are subequal in length, lanceolate, margins 

 fringed with short spinules and long plumose hairs, the inner branch with small second 

 joint. Telson reaching nearly to the end of the third uroiDod, apparently without 

 spines on its dorsal surface. 



This species diff'ers from the typical species A. gigantea Chevreux in having both 

 gnathopoda subchelate and the first not slender but moderately stout. As there are 

 only the two species known, it will be well to slightly widen the characters of the genus 

 to include the species now being described. The typical species was of enormous size, 

 one of the specinicns being as much as 140 mm. long; probably when specimens of 

 both species of an intermediate size are known, it will be found that the two are more 

 nearly alike than appears from the detailed description above, which is based on the 

 single specimen obtained by the Scotia. 



(ROY. SOO. EDIN. TRANS., VOL. XLVIII., 466.) 



