ACANTHEPHYRA CRISTATA. 163 



carina, which becomes obsolete just before it reaches the posterior margin of 

 the carapace ; this crest is ornamented with seven teeth, and the anterior 

 part of the rostrum bears four more teeth on its upper margin ; the lower 

 margin of the rostrum is armed with three or four teeth. The wall of the 

 orbit is entire, the lower margin being continuous with the antennal spine 

 by suppression of the normal infra-orbital angle. A sinuous carina runs 

 from tlie antennal spine backward to the hind margin of the carapace, form- 

 ing the inferior boundary of the gastric and cardiac areas. Below the 

 branchiostegal spine a second lateral carina runs backward, and becomes 

 submarginal on the posterior border of the branchiostegite. The first and 

 second segments of the abdomen are destitute of a dorsal carina ; the third 

 and fourth are carinated, and armed with a posterior tooth, largest on the 

 third segment; the fifth and sixth segments are rounded dorsally, and the 

 fifth is furnished with a minute posterior dorsal median spine ; the posterior 

 lateral margin of the tergum of the fourth and fifth segments is armed with 

 a minute denticle just above the point of articulation with the next segment. 

 In one specimen the telson is armed with about six pairs of minute dorsal 

 spines, which are obsolete in the other specimen. In both, the posterior 

 half of the lateral margins of the telson is spinulose ; the apex of the telson 

 is imperfect in both the specimens examined. The eye is large, black, and 

 set obliquely on its peduncle ; the inner margin of the peduncle is furnished 

 with a rather long, blunt process, or tubercle. The antennal scales are about 

 equal in length to the rostrum ; they are armed with an external apical 

 tooth, and are serrate on their inner margin. 



Length, 78 mm. ; rostrum, 13 mm. ; carapace, including rostrum, 27.5 

 mm. ; antennal scale, 12 mm. 



Station 3361. 1471 fathoms. 1 specimen. 

 " 3381. 1772 



This species, like A. dehilis A. M. Edw. {=A.gmcilis Smith) and Systel- 

 laspis lanceocaudaia Bate, has no carina on the dorsal surface of the fifth and 

 sixth abdominal segments, and the orbit is continuous below with the an- 

 tennal spine. On these characters, taken in connection with the large size 

 and small number of the eggs, Spence Bate established the genus Systcl- 

 laspis* A genus founded on a physiological peculiarity combined with such 

 trivial .structural characters can hardly be accepted as a valid one. A. cns- 

 tuta differs from A. dchilis in having a much shorter and fewer-spined rostrum, 



* Kep. Challenger Macrura, p. 757, 1888. 



