66 THE VOYAGE OF H.M.S. CHALLENGER. 



the upper side of the pseudorostral projection ; visual elements imperfectly developed. 

 Exposed part of trunk very short, though composed of five well-defined segments. 

 Segments of tail keeled laterally. Antennae in male attaining the length of the body. 

 First pair of legs comparatively short, not projecting in front of carapace ; second pair 

 rather stout, with terminal joint very elongate and linear ; the three posterior pairs of 

 legs successively decreasing in length and only sparingly supplied with bristles. Inner 

 branch of uropoda considerably larger than outer, with inner edge spinous. 



Remarks. — The species of the present genus are easily known by the exceedingly 

 large and vaulted carapace, which in most of the species exhibits a very marked sculpture, 

 partly in the form of keels and partly as variously shaped protuberances. As to the 

 limbs, the comparatively small size of the first pair of legs also furnishes a marked 

 and characteristic feature. No less than ten species belonging to this genus have been 

 described, seven of which occur off the Norwegian coast, two in the Mediterranean, and 

 one in the West Indian Archipelago. Two new species are now added from the 

 Challenger Expedition. 



14. Campylasjns pacifica, n. sp. (PI. X. fig. G). 



Specific Characters. — $. Carapace enormously developed, occupying more than 

 half the length of the body, and being produced posteriorly so as to arch over the 

 exposed part of the trunk ; dorsal surface boldly vaulted; anterior part only slightly 

 produced ; pseudorostral projection very short ; subrostral notch rather shallow. Sur- 

 face of caraj^ace without any keels or protuberances, but slightly uneven dorsally. 

 Ocular lobe rather broad, containing a whitish eye-pigment. Penultimate caudal seg- 

 ment entire, not subdivided. Uropoda very elongate, attaining the length of the four 

 posterior caudal segments taken together, branches scarcely half as long as scape. 

 Length, about 3 mm. 



Remains. — The present species seems to be most nearly related to the Mediterranean 

 form, Campylaspis glabra, G. 0. Sars, from which it however differs by the somewhat 

 more slender form of the body, by the carapace being slightly uneven dorsally, by the 

 shorter pseudorostral projection, and by the presence of a distinct, though rather shallow 

 subrostral notch. 



Description. — I have only had an opportunity of examining a single female 

 specimen of this form. The specimen, which had been mounted in Canada balsam, is 

 fairly well preserved, and measures in length about 3 mm. 



The form of the body (see PI. X. fig. 6) is comparatively somewhat more slender 

 than in most of the other species, with the anterior division greatly dilated and some- 

 what longer than the posterior, if the uropoda are excepted. 



The carapace is of quite a prodigious size, occupying more than half the length of 



