REPORT ON THE AMPHIPODA. 1547 



and longer than the outer, not quite so long as the inner of the first pair, denticulate on 

 the lower part of the outer, and more loosely on the lower half of the inner margin ; 

 peduncles of the third pair wide apart, much shorter than the rami ; the rami widening 

 greatly from the base, so as to be broadest below the centre, thence narrowing to an 

 acute apex, the outer ramus rather the shorter, with smooth outer margin, and the lower 

 part of the inner denticulate, the inner ramus much the broader, denticulate on both 

 margins below the widest part. 



Telson reaching a little be)'ond the rami, subequal in length to the coalesced fifth 

 and sixth segments, longer than broad, the breadth nearly three-quarters of the length, 

 in outline forming an elongated inverted arch, the apex almost acute. 



Length, in the position figured, two-fifths of an inch. 



Locality.— April 3, 1875 ; North Pacific, lat. 24° 49' N., long. 138° 34' E.; surface 

 temperature, 71° '5. One specimen, male. 



Remark. — The specimen described by Spence Bate from some unknown locality was 

 three-quarters of an inch in length, therefore much longer than the Challenger specimens. 



Brachyscelus crusculum, Spence Bate (PI. CXCVL). Specimen B. 



This specimen was in the first instance figured and described as a distinct species, but 

 I think it may be regarded as the adult male form of Brachyscelus crusculum. The 

 head is not smoothly rounded as in specimen A ; the angles of the first three pleon- 

 segments are similar. 



Upper Antennse. — First joint of the peduncle cylindrical, longer than broad, the 

 following joint or joints very small, imperfectly developed ; the first joint of the flagellum 

 large, and with a large brush of filaments on the convex side, the straight upper margin 

 having a series of broader filaments, the apex narrow, not produced ; the next joint 

 narrow, a little bent, having five groups of filaments ; the third joint shorter and abruptly 

 narrower, with filaments at the apex. 



Lower Antennae. — The third joint of the peduncle elongate, the basal half curved, 

 the distal end dilated, fringed like the remaining joints with numerous short filaments, 

 the fourth joint decidedly longer than the third, straight, the fifth joint a little longer 

 than the fourth, the first of the flagellum longer than the third, but shorter than the 

 fourth or fifth joint of the peduncle, the second joint about a quarter the length of the 

 first. 



Mandibles. — Trunk elongate, narrow, the point of the distal triangle forming a blunt 

 tooth at the top of the cutting edge ; the first joint of the palp much longer than the 

 third, which is itself longer than the second. 



Above the figure of the maxUlipeds, in the middle of the Plate, the head is figured 



