42 HISTORY OF BRITISH CRUSTACEA. 



latero-anterior teeth five. Eye-peduncles short. Tarsi of 

 hind legs very narrow and lance-shaped. 



Carcinus m^enas, Linn. sp. Common Shore Crab. — 

 When alive, greenish ; carapace slightly granular in front ; 

 front ending in three rounded lobes; inner edge of wrist 

 with a strong spiue. 



The most common species on our coasts. It is very vo- 

 racious. Dr. James Howden refers to this Crab and the C 

 Pagurus, as being often very injurious to the salmon-fisher. 

 He has seen trout and mackerel reduced to skeletons in a 

 very short time, and grilse and salmon often rendered unfit 

 for market by an unseemly scar, the work of these marauders. 

 In the Moray Firth, according to the Rev. G. Gordon, it is 

 occasionally employed as bait ; particularly the " peelarts," 

 or those specimens which have just cast their shells.* An 

 anomalous parasite, named Sacculina Carcini, is found on 

 this Crab : it is apparently destitute of the organs of man- 

 ducation.t 



Polybhis in a distinct family from Porfunus, which he names Vlatyonychida, 

 after its characteristic genns, Platyonychus. 



* Zoologist, p. 3682. f J. V. Thompson, Ent. Mag. iii. 452. 



