100 PERCY SLADEtf TRUST EXPEDITION 



inapplicable to the new species, which is well separated from its predecessor by the 

 absence of this fusion. The two are separated further by more easily observable 

 characters as follows : 



Without upturned rostral process; dorsal surface strongly spinulose. 1.' A. normani, 

 Stebbing. 



With strongly upturned rostral process; dorsal surface smooth. 2. A. reidi, n. sp. 



13. Argathona reidi, n. sp. (Plate 9 a.) 



The rather small head is scarcely half as long as broad. The rostral process is 

 upturned so as to present in profile a flat top, its curvature over-arching a shaded 

 hollow, behind which the distal part of the head forms a raised triangle, with a faintly- 

 marked tubercular swelling at each end of its base. The eyes are wide apart, tending to 

 reniform, diverging to touch the lower margin outside each tubercle. The width of the 

 perseon increases from the first segment, which is slightly the longest, to the fourth. 

 The three following segments are shorter. The side-plates are diagonally furrowed. The 

 first pleon segment is completely hidden. The four following are short. The telsonic 

 segment is wider at the base than its length and forms a broadly round-ended triangle, 

 not reaching quite so far back as the inner ramus of the uropods. Like them it has 

 a close fringe of not over-long plumose setse, interspersed with little horny spines. 



The first antennae reach the middle of the last joint of the peduncle of the second. 

 Both pairs are in close agreement with those of A. normani. The flagellum of the first 

 pair has twelve joints, most of them carrying filaments. In the second pair the flagellum 

 is composed of twenty-nine to thirty joints. 



The frontal lamina is pentagonal, not very large. The epistome, emarginate at the 

 top, has widely divergent arms, embracing a rather small area for the upper lip. The 

 latter and also the lower lip were not clearly made out. 



The mandibles are very massive at the base, near to which the palp is implanted, 

 having its second joint much the longest, this and the third being armed with serrate 

 spines. That which I have spoken of as a feeble blade, of quasi molar homology, in the 

 other species, appears to be present here also, but so entangled in a transparent 

 membrane, that I feel little confidence in its interpretation for either species. 



The first maxillae agree with those already described, except that the inner plate 

 is apically more squarely truncate. 



In the maxillipeds the sixth joint is more robust than in the other species. 



The limbs of the perason are also very near to those of A. normani, the superior 

 robustness of the perseopods being no doubt related to the superior size of the new form. 



The second pleopods have the male appendix of the same shape as in the other species, 

 but not reaching the end of either ramus instead of extending a little beyond both. 



The peduncle of the uropods is much produced. The inner ramus is much broader 

 than the outer, and produced considerably beyond it, though in actual length it does 

 not greatly exceed it. Both are round-ended. 



Length 22 mm. Breadth about 10'5 mm. 



