606 THE VOYAGE OF H.M.S. CHAIXENGEE. 



coupling-spines at the distal end on the inner side of each peduncle are two in number, and 

 something like those of Tcditrus locusta ; the shafts are a little bent and exceedingly short, 

 while the heads by comparison are very broad, showing a retroverted tooth on either side. 

 Uropods. — The first have the peduncle longer than the subequal rami ; both 

 peduncle and rami spined on the edges, a group of spines at the tip of each ramus, one 

 of predominant size. In one of the specimens examined the rami on one side were much 

 shorter than those on the other. The second uropods similar to the first in armature, 

 but shorter, the peduncle subequal in length to the rami. The third uropods with short 

 peduncle and short ramus spined on the outer edges ; the peduncle tapering distally, 

 broad below, from above looking as if cylindrically folded over. 



Telson. — Broad at origin, tapering to two small distal lobes, these and the lateral 

 margins set with spines ; a median suture runs from the base some way towards the 

 meeting point of the distal lobes. The sixth segment of the pleon scarcely visible from 

 above folds beneath the whole length of the telson. 



Length about half an inch, sometimes reaching seven-tenths, without counting the 

 antennae. 



Locality. — Fifty-two specimens were taken on the shore at Juan Fernandez. The 

 species is named after Alexander Selkirk, whose romantic story is cormected with that island. 



HemarJcs. — Orchestia serrulata, Dana, from New Zealand, seems to be its nearest 

 ally, but the two species ai-e separated by numerous difiereuees in detail, among which 

 may be noticed the first gnathopods in the female, the palm of the second gnathopods in 

 the male, the relative lengths of the perseopods. 



Family L Y s i A N A s s i D ^, G. 0. Sars, 1882. 



For the original definition of the subfamily Lysianassinse, Dana, see Note on Dana, 

 1849 (p. 229).^ The subfamily Lysianassinee, Boeck, 1870, is changed by Sars into the 

 family Lysianassid^, without further definition. Boeck's definition of it in 1872 is as 

 follows : — 



" Upper Lip and Epistome more or less prominent. 



" Mandibles elongate ; cutting edge broad, not dentate or only furnished with very 

 few teeth on the inner margin ; an inner plate on the left mandible ; molar tubercle 

 small, more or less prominent ; spine-row furnished with few blunt and often very small 

 teeth ; palp elongate, triarticulato. 



" Loicer Lip elongate ; inner plates little, near the apex [? generally absent]. 



" Fii^st Maxillse with two-jointed palp ; rarely without palp. 



" Second Maxillse more or less elongate. 



1 For Schi0dte's Trochalognatlia, see Note on Schiodte, 1875 (p. 449). 



