PHQXUS PLUMOSUS. 
149 
legs ; the coxa is very short, but the thigh is largely 
dilated, and postero-inferiorly produced to a blunt point, 
reaching as far as the wrist ; the inferior and posterior 
margins are slightly crenated, each crenulation emitting 
a solitary hair ; all the joints, except the finger, (which 
is long, straight, and styliform,) are subequally short. 
The caudal appendages are free from hairs or spines; 
they terminate subequally, the antepenultimate pair 
being slightly the longer, and the penultimate pair the 
shortest. The branches are subequal, those of the last 
pair being rather less pointed than those of the two 
preceding pairs. The central piece is double, but not 
so long as the peduncle of the posterior pair of caudal 
appendages. 
The colour of the animal is corneous and transparent. 
The structure of the tissue, under the microscope, is seen 
to be minutely granular. 
Kroyer, in his description, says that a few spines exist 
upon the third and fourth joints of the peduncle of the 
inferior antennae in P. Holbolli , but that they are absent 
in P. plumosus. In one specimen of P. Holbolli the hairs 
upon the inferior antennae are scarcely robust enough to 
be called spines ; whereas in P. plumosus there are a few 
plumose hairs, of which Kroyer makes no mention. In 
other respects the animals appear to correspond with 
Kroyer’s description, and we do not feel justified in sepa- 
rating them upon such immaterial distinctions. The only 
difference between P. plumosus and Stimpson’s specimen 
of P. fusiformis consists in the American specimen having 
what the author of its description calls “more nails on 
third and fourth legs.” Now these so-called “ nails” we 
take to be the long lateral spines that impinge against 
the sides of the fingers of the third and fourth pairs 
of legs. 
