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 Tanais 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 potassae" 



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 Laminaria saccharina," 

 near Cumbrae. 



