1350 THE VOYAGE OF H.M.S. CHALLENGER. 



broad, the length of the joint rather less than that of the three following joints together, 

 the little rounded apex of the front margin carrying a setule ; the second joint longer 

 than broad, with the distal part of the front margin slightly excavate, having a setule 

 but no tooth at the top of the excavation ; the third joint not half the length of the 

 fourth, with an upward directed point at the top of the front margin ; the fifth joint 

 longer than the third, shorter than the fourth, straight, slightly tapering, with setules 

 about the apex, which is produced to a point on one side of the finger ; the finger minute, 

 with broad base and narrow strongly bent tip. 



Fifth Perieopods agreeing with the fourth in the shape of the joints, but differing in 

 their relative proportions ; the first joint considerably longer than in the preceding pair, 

 longer than all the other joints together of its own limb, but not so long as the corre- 

 sponding joints of the fourth perseopods ; the third joint more than half the length of 

 the fourth ; the fourth not much longer than the fifth. 



Pleopods. — Coupling spines small, with an apical pair of retroverted teeth, and a pair 

 below the apex ; the cleft spine with very slender arms, the serrate one the longer, the 

 other with a very slight subapical dilatation ; the inner ramus with seven joints, of which 

 the first is not very elongate, much excavate at the base on the outer side; the outer 

 ramus with eight or nine joints, the first having a process of the peduncle attached to its 

 surface. 



Uropods. — Peduncles of the first pair rather longer and narrower than those of the 

 third, twice as long as the outer ramus, which is a little shorter than the inner ; the 

 outer ramus has its inner edge, the inner its outer, finely pectinate ; the peduncles of the 

 second pair narrow, about once and a half as long as the outer ramus, which is shorter 

 than that of the preceding pair, the inner margin finely pectinate ; the inner ramus 

 almost smooth, or with the pectination of the inner margin scarcely perceptible, narrower 

 than the outer and about half its length ; the peduncles of the third pair about twice as 

 long as the outer ramus ; the rami as in the first pair, but rather shorter. 



The Telson an extremely thin lamina, forming about three-quarters of a circle, 

 affixed to the preceding segment in such a position that its apex only just projects 

 beyond the ventral opening of the segment between the bases of the third uropods. 



Length. — Three-tenths of an inch. 



Locality. — Station 103, August 22, 1873; off Sierra Leone; lat. 2° 52' N., long. 

 17° 0' W.; surface-net, 100 fathoms ; surface temperature, 77°. One specimen, female. 



Remarks. — It is perhaps a rather significant circumstance that the specimen of 

 Phronima pacifica should come from the Atlantic, while the specimens which I have 

 been led to assign to Phronima atlantica come from the Pacific. 



