MUSEUM OF COMPARATIVE ZOOLOGY. 207 



where it is produced into a strong posterior tooth which overhangs the anterior 

 part of the fourth segment ; the three following segments are furnished with 

 minute posterior teeth. The posterior half of the telson in the uni(|ue speci- 

 men at hand is missing ; there is one pair of minute marginal spines at tlie 

 hind end of the remaining proximal half. The eyes and eyestalks are well de- 

 veloped, the stalks broadening toward the distal end, and projecting a slender 

 blunt process on the inner side close to the cornea ; the eye itself is as broad 

 as the distal end of the peduncle. 



The basal segment of the antenna is armed with an acute external spine ; 

 the autennal scale is long, gradually narrowing distally to the apex, which is 

 furnished with a small spine. 



The thoracic appendages have the form characteristic of the genus Acarithe- 

 phyra, and appear to oifer no important specific characters. 



Length, 87 mm. ; carapace, 27 mm. ; antennal scale, 16 mm. 



Station 3381. 1772 fathoms. 1 male. 



Notostomus fragilis, sp. nov. 



Dorsal line of carapace convex and keeled from anterior to posterior margin, 

 anteriorly produced into a short, acute rostrum, which does not exceed the eye- 

 stalks in length ; the dorsal carina is armed with seven or eight minute teeth 

 on the anterior gastric region and the basal portion of the rostrum ; lower 

 margin of rostrum unarmed. A longitudinal carina on each side of the cara- 

 pace begins near the orbit, above the infra-orbital spine, and runs back to the 

 posterior margin ; another carina runs obliquely downward and backward, 

 dividing the branchial from the hepatic regions. The inferior lateral carina is 

 obsolete except for a short distance behind the spine which lies near the ante- 

 rior margin of the carapace behind the base of the second antenna. 



The abdomen is strongly compressed, the third, fourth, fifth, and sixth seg- 

 ments dorsally carinated ; the carina terminates in a small tooth at the hind 

 end of the fourth, fifth, and sixth segments ; on the fourth segment the carina 

 is divided into two parts by a deep notch about two thirds of the distance from 

 the anterior to the posterior margin of the segment. The telson is channelled 

 on the dorsal side, and is tipped with two long spinous setae. 



The eyestalks taper from the base to the tip ; their outer and upper mar- 

 gins are nearly straight, but their inner and lower surfaces are swollen ; on the 

 inner side of each stalk, a little way behind the eye, there is a blunt tubercle. 

 The eye itself is small and black. The integument of the eyestalk is trans- 

 parent, and when held to the light discloses the optic ganglion within, giving 

 off' a nerve to the retina and another to the tubercle on the inner side of the 

 stalk. 



The basal segment of the antennule is armed with a very small but sharp 

 external spine. The outer side of the second antenna, on the contrary, is 

 unarmed. The antennal scale is very broad, oval, and furnished with a small 



