A REVIEW OF THE MYSIDACEA 217 



(3) Antennal scale (fig. 90, a,b) much shorter than the antennular 

 peduncle, six times as long as broad, with a well marked distal joint. 



(4) The labrum is without the spinelike process characteristic of 

 most members of the genus. 



(5) The thoracic limbs are long and slender. The endopod of the 

 third to the eighth pairs is divided into five to seven subjoints. 



(6) The telson (fig. 90, d) is linguiform, twice as long as broad at 

 the base, apex bluntly rounded. The lateral margins are armed with 

 13 to 15 larger spines somewhat widely spaced and extending about 

 five-sixths of the way along the margins from the base ; between the 

 last four or five large spines are a varying number of small spines ; the 

 whole of the apex posterior to the last pair of large spines is armed 

 by a very closely set row of small spines, which are more like the 

 closely set teeth of a saw than a series of articulated spines. 



(7) The inner uropod (fig. 90, c) has a single spine near the 

 statocyst. 



(8) The fourth pleopod of the male (fig. 90, /) is long and slender; 

 the proximal joint of the exopod is 10 times as long as the distal ; the 

 terminal setae are twice as long as the distal joint. 



This very distinct species is readily identified by its elongate eye, 

 the short antennal scale, and the form and armature of the telson. 



ACANTHOMYSIS PSEUDOMACROPSIS (Tattersall) 



Figures 91, 92 

 Neomysis pseudomacropsis Tattersall, 1933, p. 14, figs. 7, 8. 



Occurrence. — Bering Sea region : Bering Island, L. Stejneger col- 

 lector, 6 adult females, breeding; Petropavlovsk, Kamchatka, col- 

 lected by the Albatross, 1 adult male ; Albatross station 3235, 1 female, 

 1 male. 



Distribution. — Hitherto this species was known only from the coast 

 of British Columbia. The present records indicate a considerable 

 extension northward to the Bering Sea and down the east coast of 

 Siberia to Petropavlovsk. 



Remarks. — This species may be recognized by the following char- 

 acters: (1) The carapace (fig. 91, a) is hardly produced into a rostral 

 plate ; the front margin is broadly and evenly rounded and the antero- 

 lateral corners acute. (2) The eye (fig. 91, a; 92, a) is elongate but 

 less so than in A. macropsis; it is two and a half times as long as broad 

 and the cornea occupies the distal third. The eye is shorter than the 

 antennal scales. (3) The antennal scale (figs. 91, a; 92, d) is about as 

 long as the antennular peduncle, five times as long as broad, with a 

 distinct distal joint. (4) The labrum has a small spinous process. 

 (5) The endopod of the third to the eighth thoracic limbs (fig. 92, e) 



