■ -. A-^^ 



ACANTIIEPHYRA CRISTATA. 



163 



i- 



f 



I 



* 



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 

 mari;!:in 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 the 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 seirments is armed with 



. E 



■'1 

 E 



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

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

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

 half ol: 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 

 Avith 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 maririn. 



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

 mm. ; antennal scale, 12 mm. 



Station 3361. 1471 fathoms. Ispeclmen. 



a 



3381. 1772 



£i 



u 



This species, like A, debiUs A. M. Edw. {= A. gracilis Smith) and Systeh 

 laspis lanceocaudala 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 those characters, taken in connection with the large size 

 and small number of the eggs, Spence Bate established the genus Si/steh 



A genus founded on a physiological peculiarity combined with such 

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

 tata difiers from A. dchilis in having a much shorter and fewer-spined rostrum, 



* 



Eep. Chall(-iigor Macrura, p. 757, ISSS. 



