1420 THE VOYAGE OF H.M.S. CHALLENGER. 



that this is probably not Kr0yer's original specimen, but that Kr0yer was really describing 

 a specimen of Pdrathemisto, as his figures indicate ; in that case, however, he considers 

 that there is little or nothing to separate Parathemisto oblivia (Kr0yer) from the later 

 Parathemisto abyssorum, Boeck, of which he has found several specimens from Green- 

 land in Kr0yer's collection. Under these circumstances it is reasonable that the specific 

 name oblivia should be dropped on the ground of uncertainty and insufficient description. 

 The next species claiming admission into the genus is Hyperia trigona, Dana, 1852, 

 "length six to eight lines," coming " probably from the Lagulhas Bank, near Cape Horn." 

 The Brit. Mus. Catal. Amph. Crust., p. 297, gives the measurement of this species as 

 "Length 2%* ns °f an inch = '6-8 lines' (Dana)." Bovallius, Arctic and Antarctic 

 Hyperids, p. 568, renames the species Parathemisto trigona, but gives the measurement 

 as "Length 25-30 mm.," adding " Hab. Off Cape Horn (Dana)." For Hyperia oblivia, 

 Spence Bate, 1857, Bovallius gives the name Parathemisto longipes. The species is 

 rather obscure, but such as it is, it must bear the specific name gracilipes, proposed by 

 Norman in 1869. The remaining species included in the genus are Parathemisto 

 compressa (Goes), 1865, and Parathemisto japonica, Bovallius, 1887. 



Parathemisto pacifica, n. sp. 



The lower margins of the first three pleon-segments a little serrate and produced into 

 small acute points ; the hind margin bulging out beyond the postero-lateral angles. 



Upper Antennas. — First joint of the flagellum (in the male) as long as all three joints 

 of the peduncle, with fourteen pairs of filaments along the convex margin, the apex 

 narrowed ; fourteen joints follow, of which the first is the shortest, a little longer than 

 broad. 



Lower Antennas. — Last joint of the peduncle considerably longer than the preceding 

 joint ; first joint of the flagellum the longest, nearly as long as the last of the peduncle, 

 but much more slender, a little bulbous at the base ; sixteen slender joints follow in 

 the specimen examined. 



Upper Lip. — The distal emargination making one lobe half an oval, the other nearly 

 square, yet with the end a little convex. 



Mandibles. — The trunk compact, much shorter than the palp ; the cutting edge 

 with fourteen denticles, of which the lowest is the largest, a little apart from the rest ; 

 the secondary plate of the left mandible widens from a narrow neck, its broad distal edge 

 having thirteen denticles which lie very near to those of the principal plate ; behind the 

 cutting plates there is the usual tuft of spines and the broad denticulate molar tubercle ; 

 •he first joint of the palp is straight, elongate, yet shorter than the third ; the second 

 joint is slightly bent, longer than the third. 



Lower Lip. — The distal margin of the principal lobes flattened, strongly ciliated. 



