PARATANAIS RIGIDUS, 143 
tuberance armed with two or three minute cilia, and 
carrying at the extremity five long and strong hairs. 
The outer ramus is about half the length of the inner, 
single-jointed, armed near the middle of the outer 
margin with a single hair, and also with a second 
solitary hair on the outer side of the apex. 
The species bears a near resemblance to that described 
by Lilljeborg under the name of Yanais brevicornis. 
Lilljeborg describes that species as having the inner 
ramus of the posterior pair of pleopoda biarticulate, 
whereas in this it is uniarticulate, but the small ciliated 
protuberance near the middle of the inner margin, together 
with the circumstance that from that point a slight bend 
or change of direction takes place, may have suggested 
the idea of a second articulation to the author of that 
species, as it was a question which we could not determine 
until we had treated the specimen with “ liquor potasse.” 
So well, otherwise, does this animal correspond with 
Lilljeborg’s description, except in the number of joints 
of the upper antenna, that had it been described by any 
less experienced observer, we should have considered the 
two as belonging to the same species, assuming that the 
points in question had been misinterpreted. 
The only specimen that we have seen of this species 
was sent to us by Mr. Robertson, of Glasgow, who 
‘dredged it at the roots of Zaminaria saccharina,” 
near Cumbrae. 
