REPORT ON THE AMPHIPODA. 1583 



Oxrjcephalus clausi, Bovallius (f), (PI. CCII.). 



The rostral tract of the head much shorter than the ocular, with the edges scarcely 

 serrate ; the head only slightly constricted at the base ; a faintly marked central carina 

 along the back of the head and peraeon, tuberculated along the peraeon, and accompanied 

 by two similar lines at intervals on either side ; the first three segments of the pleon 

 have the lateral carinse less conspicuous, the remaining segments being apparently 

 without them; the first segment of the pleon is the largest, the next three successively 

 diminishing in length and depth ; the postero -lateral angles of the first three segments 

 produced into a short sharp point, behind which, at some distance, the hind margin 

 forms a sinrilar point, from which in the third segment, it runs forward parallel to the 

 lower margin ; the margins serrate near the produced points. 



Eyes large, nearly twice as long as the portion of the rostrum beyond them, not 

 meeting at the top of the head. 



Upper Antennas with their bases in front of the eyes, pointing backwards as they 

 lie in the ventral cavity of the head ; the peduncle broad, the first joint widening 

 from the base, scarcely longer than its greatest breadth.; the second joint as wide as 

 the first, only about a third as long ; the first joint of the flagellum apically tapering, 

 much longer than the peduncle, with transverse rows of filaments ; the three following 

 joints linear, bending outwards, much shorter than the first joint, the second joint 

 about equal in length to the two following united, much broader, with a setule near 

 the apex on the outer side ; the third joint not half the length of the fourth ; the 

 fourth tipped with three setules. 



Lower Antennas consisting of four stout joints folded upon one another, the first a 

 little longer and stouter than either of the two following, the fourth a good deal shorter 

 and thinner ; the first three widen a little distally with a slight curve, the fourth distally 

 becomes narrow and straight, then tapering to a rounded end. This form does not 

 represent the full development of these organs. 



Mandibles small, of the same form as in the female, but with a palp, of which the first 

 joint is not quite so long as the last of the lower antennae, longer than the second and 

 third joints together ; the second shorter than the third ; the third tapering to an acute 

 apex, curving inwards. 



Maxillipeds small, the outer plates not reaching far beyond the inner one. 



First Gnathopods much smaller than the second, yet not so much so as in the 

 Atlantic specimen, with which in general they agree. 



Second Gnathopods similar to those of the Atlantic specimen, but the long hind 

 process of the wrist has an almost smooth margin facing the hind margin of the hand, 

 most of which is finely serrate ; the hand is as long as the front margin of the wrist. In 

 the female specimen the process of the wrist has the inner margin tuberculated as in the 



