SPHyEROMA SERRATUM. 407 



formed into a distinct species, Sph. trigonum, by Risso 

 (Crust, de Nice, p. 147). 



When alive, the body is ashy coloured or whitish, 

 varied with reddish and dark grey ; the eyes black ; the 

 antennae fulvous; the legs ashy, with fulvous claws tipped 

 with black. 



Young individuals, measuring not more than two lines 

 in length, have the outer edges of the side appendages of 

 the tail (uropoda) entire/and not serrated. 



This species lives in numerous societies under stones 

 and amongst the pebbles and gravel of the coast ; and is 

 found on the English and French coasts of the English 

 Channel, from Kent to Cornwall, and in the Medi- 

 terranean. We have dredged fine specimens in Plymouth 

 Sound in the month of August. Dr. Kinahan obtained 

 it in the River Lagan, Belfast, and in the River Dodder, 

 Dublin. We have observed quantities in the brackish 

 streams on Loughor Marsh, near Swansea, mixed with 

 Palcemon, Carcinus, and Talitrus. 



