1578 THE VOYAGE OF H.M.S. CHALLENGER. 



of the third and fourth perseopods have a laminar expansion. The fifth perseopods more 

 or less reduced, but having the full number of joints, the first triangularly laminar. The 

 uropods with two lanceolate rami. The telson triangular." 



Without being able to give any definite information as to the lower lip and maxdlae 

 in this genus and the other genera of the same family, I may express an opinion that 

 these organs are not absolutely unrepresented, but that they consist of delicate and more 

 or less rudimentary plates, which are almost inevitably torn and disfigured when the 

 mandibles are drawn away from the maxillipeds. 



Oxycephalus clausi, Bovallius, $ (PL CCL). 



1879. Oxycephalus piscator, Claus, Die Gattungen und Arten der Platysceliden, p. 4L 



1887. Oxycephalus clausi, Bovallius, Systematical List of Amph. Hyper., Bihang till K. Svensk. 



Vetensk.-Akad. Handl., Bd. 11, No. 16, p. 35. 

 1887. Oxycephalus piscator, Claus, Die Platysceliden, p. 69, Taf. xxii. figs. 1-9, Taf. xxiii. figs. 1-8. 



The back carinate from the tip of the rostrum to the apex of the telson, the carina 

 interrupted by depressions between the segments of the perseon and to some extent by 

 depressions across the segments of the pleon ; the proximal half of the head of a bulbous 

 oval form, almost entirely occupied by the great eyes with their innumerable ocelli ; the 

 distal half a triangle much longer than broad, the end rounded except quite at the apex, 

 which forms a small point ; the outer margin of the whole head serrate ; viewed laterally 

 the outer or lower margin is sinuous, convex at the eye, concave at the rostrum which 

 forms a sort of prismatic base, along the underside of which lie the two little antennae. 

 On either side of the central carina, a lateral carina is developed in a more or less 

 disconnected manner, as well on the rostrum as on the segments of the perseon and the 

 first three of the pleon ; of these latter the posterolateral angles are produced into sharp 

 points, above and beyond each angle the hind margin being also produced into a sharp 

 point, with a faintly serrate cavity below and a convex or sinuous tract above ; the 

 coalesced fifth and sixth segments are equal in length to the telson, and coalesced with it. 

 Much of the animal is finely scabrous. 



Upper Antennas but little exceeding in total length the breadth of the wrist of the 

 second gnathopods. The first joint about three times as long as broad ; the second joint 

 very short, twice as broad as long ; the first joint of the flagellum longer than the 

 peduncle, fringed on the outer side with about eighteen short filaments ; the second joint 

 about a fifth of the length of the first and much narrower, with a subapical pair of 

 short filaments ; the third joint shorter than the second, linear, a little curved, tipped 

 with a spinule. 



Lower Antennae wanting (in the female). 



Upper Lip transversely oval. 



