ISOPODA OF THE 'LIGHTNING' AND OTHER EXPEDITIONS. 123 



male (ill. d, <j , and in. pi. v, d ) these segments are much more developed and 

 distinct, though the segmentation is incomplete, and are equal in length to the last 

 two segments of the perseon. 



Telson and uropods so constructed and uniting as to resemble nearly a cylinder, with 

 one side (the dorsal), as it were, cut obliquely away. The telson has the apex truncated, 

 and is of the same length as the inner branch of uropods. Outer branches of uropods 

 nearly meeting at their bases dorsally, broadly lanceolate, curved, rather longer than 

 the first joint of the inner branch ; end of telson and margin of both branches of 

 uropods crenated. 



Eyes distinct, black. 



Antennas : upper in female shorter than lower, with a flagellum consisting of one 

 long articulation, which terminates in a tuft of setae; lower with second joint of 

 peduncle greatly expanded distally ; third very small, fourth rather longer, fifth equal 

 length of third, flagellum four-jointed. In male (in. d, <j ) the upper antenna? are 

 much more developed, and as long as the two first segments of the body, and furnished 

 with a thick flagellum of numerous articulations. 



First gnathopods (iv. gn 1 2 ) with an ovate or pyriform hand, which has the upper 

 proximal portion well rounded ; palm with a well-developed process projecting forwards 

 near the base ; finger strong, unguiculated, the unguiculus black ; front margin of wrist, 

 hand, and finger crenulated. 



Second gnathopods with the two upper joints subequal, the third short, strongly 

 lobed posteriorly ; fourth very minute, triangular ; fifth as long as upper joints, and 

 equal to third and fourth together, nearly parallel-sided ; front margin pectinated, and 

 bearing a single distal spine ; finger rather more than half length of hand, strong, 

 apparently not capable of closing on the hand, itself unguiculate and having a spine at 

 the base of the unguiculus. 



Last perseopods with basos and ischium subequal, two following joints rather shorter 

 and subequal to each other ; fifth as long as upper joints, and having the palm pecti- 

 nated and bearing a single distal spine ; finger half as long as fifth, unguiculate, a spine 

 at the base of the unguiculus. 



Length 8 millim. 



Coasts of Devon and Cornwall. The specimens examined were found by T. R. 

 B,. S. at Torquay. 



It will be seen from the foregoing description that the male, which was not previously 

 known, differs from the female in the greatly developed flagellum of the upper antennas 

 and in the more produced and segmental character of the pleon. We think it probable 

 that the male has not fully attained its several characters, and that when quite mature 

 the antennae would have the flagella even more developed and ciliated. 



