I. '08. 125 



Antennal scale less than four to fully six times as long as 

 wide and from one-half to three-quarters the length of the 

 carapace. 



Penultimate joint of antennular peduncle equal to, or 

 fully twice the length of, the ultimate joint. 



External maxillipede reaching beyond the apex of the 

 antennal scale by one or by two of the terminal joints. 



Second pereiopods equal or unequal ; the right often quite 

 twice the length of the left with about forty carpal joints, 

 frequently shorter, with a corresponding reduction in the 

 number of carpal joints, occasionally equal in length to the 

 left with a minimum of eleven joints in the carpus. Left 

 leg with eleven to twenty-one carpal joints. 



Fifth pereiopod varying from slightly longer to consider- 

 ably shorter than the fourth ; reaching beyond the apex of 

 the antennal scale by scarcely the length of the dactylus or 

 by as much as the dactylus, propodus and part of the carpus. 



The last three pairs of pereiopods comparatively stout or 

 slender. 



In respect of the size of the eye and proportional lengths of 

 the rostrum, antennal scale, and joints of the antennular 

 peduncle, a closely similar range of variation has been noticed 

 by Miss Eathbun (1906) in specimens taken in American 

 waters off the coasts of Florida and California. Among these 

 examples some were found in which both pereiopods of the 

 first pair possessed chelae. This very remarkable variation 

 has not so far been met with in Irish waters. 



In all the Irish specimens the telson is sulcate above and 

 provided with six apical spines, of which the intermediate pair 

 are the longest and strongest. Dorsally two paii's of spinules 

 are usually found. 



General distrihution. — In European waters Processa cana- 

 Uculata extends from S. Norway to the Mediterranean, in- 

 cludmg the Black Sea. It is well distributed round the Eng- 

 lish and Scotch coasts and in certain localities is often found 

 abundantly. The species has also been recorded from Ma- 

 deira (Stimpson), S. Africa (Stebbing), Ceylon (Pearson), 

 Bermuda (Eankin), from X. Carolina to Trinidad (Eathbun), 

 from San Diego, California, to the Gulf of Panama (Eath- 

 bun) and from Japan (Ortmann). 



Irish distrihiition. — During the course of fishery investiga- 

 tions P. canaliculata has been constantly found oft' the east 

 coast of Ireland. There is little variation in these specimens ; 

 all are of the slender form and correspond closely in character 

 with tlie large female noticed above. In these waters the 

 species appears to be most abundant between 20 and 40 

 fathoms : on several occasions it has been trawled in large 

 numbers in the neighbourhood of Eockabill Lighthouse. 



Off the south and w.est coasts the species seems to be widely 



