ISOPODA OF THE ' LIGHTNING- ' AND OTHER EXPEDITIONS. 87 



4. Apseudes DNCiDiGiTATUS, n. sp. (Plate XXI. fig. i.) 



This pretty little species, which has the limbs elegantly banded and mottled with 

 umber-brown, in many respects resembles A. talpa, but in some points differs from 

 all other known members of the genus. Thus the dorsal surface is almost smooth, 

 instead of being much waved and indented as in other species, while the second 

 segment of the peraeon is much more closely soldered to the first than usual, and thus 

 becomes almost a part of the carapace, an approach being thus made in this species to 

 that soldering of two perseon-segments to the cephalon which is more fully carried out 

 in the new genus Sphyrapus of this Memoir. 



Frontal region (i. c) in the form of the base of an escutcheon inverted, the rostrum 

 almost evanescent, and only represented by a small point; frontal region scarcely 

 extending one fourth the length of the basal joint of the upper antennse. 



Ocular processes or alae curving a little round the upper antennse, acutely pointed, 

 and projecting forwards beyond the very short rostrum. No appearance of eyes. 



The carapace (i. d) has nearly parallel sides, not expanded at the point of origin of 

 the gnathopods. Perfeon-segments remarkably even in breadth and length, though 

 each successively very slightly narrower than the preceding ; base of second peraeon- 

 segment a little excavated on the sides in the neighbourhood of the coxal spine ; the 

 hinder corners of the segments are sharply angled, those of the penultimate and 

 antepenultimate produced backwards into minute spine-points ; antero-lateral margins 

 not spined, rounded, having a few very minute cilia ; no spines on the ventral surface, 

 except a central spine on the last segment. 



The pleon (i. l) has the epimera of the five first segments produced into spiny points, 

 which are directed backwards and are visible from above ; they bear a few minute 

 cilia, which, however, are so small as only to be seen when looked for with the micro- 

 scope, each segment has also a ventral spine (l. l). Last segment equalling in length 

 2-3 of those which precede it. 



The antennae are very similar to those of A.talpa; the upper (i. a.s) have the 

 flagellum nine-jointed, and the secondary appendage five-jointed ; the olfactory fila- 

 ments are very long, that attached to the antepenultimate articulation far overtopping 

 the end of the flagellum. The lower antennse (i. c. v.) have the antennal scale ovate, 

 reaching the end of the fourth joint of the peduncle, the filament is six-jointed. 



The first gnathopods (i. gn}) show some resemblance to those of the young male of 

 A. talpa. The basos is short and thick, the wrist long and parallel-sided ; the hand 

 short, widening rapidly, and triangular, the thumb portion not projected forward, but 

 thrust out laterally, having a central tooth, a group of cilia at the base, and a line of 

 cilia edging the distal part, which is not denticulated ; finger with several long cilia at 

 half its length on the back, while the central portion of the inner side is denticulate 

 and ciliate. 



The second gnathopods {i.gn^) are remarkably strong, the last joints much expanded, 



p2 



