BRITISH STALK-EYED CRUSTACEA. 101 



Portunus depurator, Leach. 



This species possesses several specific characteristics by which 

 it may at once be determined. Its carapace is much smaller than 

 that of P. jmber, and, instead of being velvety and dark in colour, is 

 rough, granulated, and of a pale brick-red brown. The denticu- 

 lations on the anterior portion are very defined, and the space 

 between the orbits is occupied by three sharp teeth, having a 

 smaller one on either side. 



The anterior pair of legs have the forceps much more grooved 

 and carinated than those of the former species, the spines on the 

 wrist being also much more formidable ; the remaining legs 

 retain the generic character, and differ but little in colour from 

 that of the carapace. 



This species is with ova during the summer months. The 

 eggs are carried in a large mass beneath the abdominal segments 

 of the female, and are of a dirty brown colour and very small. 



Portunus depurator appears to be an abundant species, and is 

 recorded by Bell as having been obtained at Embleton Bay, in 

 deep water, attached to the nets of the fishermen ; from Strang- 

 ford Lough and on the Connaught coast, by Mr. Thompson ; also 

 from Studland Bay and Hastings. We have obtained it in 

 numbers from the estuary of the Thames; Devon, Dorset, and 

 Sussex coasts. It is also reported from St. Andrews (occasional) ; 

 Galway, Belfast, and Dublin ; Cheshire coast (common) ; Mil- 

 ford Haven; coasts of Yorkshire and Durham; Moray Firth; 

 Hebrides ; and both coasts of Cornwall ; in the latter county it is 

 called the " Harbour" or " Mary Crab." 



It is curious that those we obtained from Weymouth were 

 generally infested with a growth of Membranipora pilosa, whilst 

 others that were obtained from the neighbourhood of estuaries 

 were invariably clean, and without parasitic growth. 



Portunus marmoreus, Leach. 



In this species the carapace is more minutely granulate than 

 that of P. depurator. The denticulations on the anterior margin 

 are by no means so defined as the following species, and the 

 space between the orbits is occupied by three teeth, which are 

 nearly as acute, but not so much projected. From its near ally, 

 P. holsatus, it differs in its generally smaller size ; also in its more 



