41 



18. Aristams (Aristceopsis) armatus, Spence Bate. 



ArUtssus armatus, Spence Bate, Ann. Mag. Nat. Hist., Sept. 1881, p. 188, and Challenger Crustacea Macrura, 

 p. 312, pla. xlv.-xlvi. 



Aristseepsis armata, Wood-Mason, Ann. Mag. Nat. Hist., Oct. 1891, p. 285. 



Rostrum in both sexes about as long as the carapace, its carina ending on 

 the gastric region. Cervical suture indistinguishable. All the crests of the 

 carapace are as in A, edwardsianus, except that they are more obtuse. 



The last 4 abdominal pleura have their postero-lateral angles mucronate. 

 The 6th abdominal somite is half as long again as the 5th. The telson is about 

 as long as the endopodite of the caudal swimmeret. 



The eyes are hardly wider than their stalk. The outer antennular flagellum, 

 in the male, is nearly as long as the basal joint of the peduncle, the inner 

 tiagellum is very long. The antennal scale reaches far beyond the antennular 

 peduncle, its tip is thickened in the male. 



The terminal joint of the mandibular palp is triangular with the inner edge 

 concave. The exopodite of the 2nd maxillipeds is singularly short and slender, 

 being very much shorter than the merus of the endopodite. 



The external maxillipeds, in the male, are stouter than any of the legs, the 

 3rd pair of legs do not reach to their tip. The carpus of the 1st pair of legs is 

 a much shorter and broader joint than that of the 2nd and 3rd pairs. The fifth 

 pair of legs reach nearly to the end of the antennal scale, their dactyli are 

 slender and pointed, but not setiform. 



The exopodites of the 1st pair of abdominal appendages are about as long 

 as the first four abdominal somites. 



The andricum is a pair of feebly-interlocking sub-triangular plates, the 

 outer edge of which is free and independent at tip. 



In the male there is a semi-elliptical acuminate plate (corresponding with 

 the " thelycum ") between the 4th pair of thoracic legs, and a spine between the 

 '5th pair. Also there is a pair of convergent spines on the coxas of the 5th pair 

 of legs. 



The first 3 abdominal sterna, in the male, are produced, in the middle line, 

 to form large compressed uncate processes. 



Colour in life deep crimson. 



In our single male the carapace and rostrum are 133 millim., and the 

 abdomen is 145 millim. long, measured in the mid-dorsal line. 



Bay of Bengal, 1748 fathoms. 



-r, , , T 6481 



Regd.rso.-g-. 



