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



shorter, by the small tooth corresponding with the outer limit of the second pair of 

 antennas being situated behind the frontal margin of the carapace, but most decidedly 

 by the different formation of the ventral portion of the pereion. In the female (fig. 

 V" ?) the calcified tubercles that carry the oviducts are large and hirsute, and a trans- 

 verse, lunate, nearly vertical plate lies behind them ; posterior to this the processes of the 

 coxae of the fourth pair of legs project nearly to the median line ; behind which is a 

 broad shield-like thelycum, and then comes a transverse bar that defines the posterior 

 extremity of the pereion. 



In the male there is a heart-shaped process in the median line between the fourth 

 pair of legs (fig. I" $ ), then a transverse bar supported by a nodular process in the 

 median line, and posterior to this the enlarged coxae of the fifth pair of pereiopoda, that 

 support the vas deferens, nearly meet in the median line. The petasma is long, narrow 

 when folded, and hooked to its fellow at the base, is nodulated, and furnished with small 

 hairs at the extremity. 



The branchiae are of generic value, but the mastigobranchial plates are long, narrow, 

 semi-forked at the extremity, and fringed with hairs. 



Haliporus obliquirostris, Spence Bate (PI. XLI. fig. 2). 

 Halipwtcs obliquirostris, Sp. B., loc. cit. 



Eostrum elevated obliquely from the orbital margin of the carapace, armed with 

 six or seven teeth on the upper surface, of which the last two are on the gastric 

 region ; none on the lower surface. Pleon laterally compressed, carinated from the 

 anterior portion of the fourth somite, and terminating in a small tooth at the posterior 

 extremity of the sixth somite. The ophthalmopod is short, being about half the length of 

 the rostrum, and the ophthalmus is orbicular. 



The first pair of antennae carries a prosartema that is not so long as the ophthalmopod, 

 and on the outer margin a short stylocerite which is scarcely as long as the eye, and a 

 strong tooth arms the outer distal angle. The second joint is quite as long as the first, 

 the third is short, and the flagella are rather more than twice the length of the peduncle. 



The second pair carries a long and slender flagellum that is nearly three times the 

 length of the animal ; in one of the specimens it is spirally coiled, it having probably 

 been injured, and is now undergoing renewal. The scaphocerite tapers distally and has 

 a small tooth on the outer margin near the extremity. The synaphipod of the mandible 

 reaches to the distal extremity of the last joint of the peduncle of the second pair of 

 antennae. 



The first pair of gnathopoda carries an ecphysis that is about half the length of the 

 meros, and is shorter and stouter than the second, which is long, slender, pediform and 

 hirsute, and supports a rudimentary ecphysis. 



