528 THE VOYAGE OF H.M.S. CHALLENGED 



Family Alpheid^;. 



This family consists of those genera that have the following common characters : — 

 The rostrum reduced to a minimum ; the ophthalmopoda short and entirely covered by 

 the projection of the frontal margin of the carapace ; the mandible carrying a psalistoma 

 distinct from the molar process, and a two-jointed synaphipod ; the first pair of pereio- 

 poda asymmetrical, on one side having the carpos short and the propodos large and normal 

 in form, and on the other very large and variably irregular ; the second pair of pereio- 

 poda long and slender, with the carpos multiarticulate and terminating in a minute 

 chela ; and, finally, the telson broad and rounded. 



Athanas, Leach. 



Athanas, Leach, Edin. Encycl., vol. vii. p. 432. 

 „ Leach, Malacos. Pod. Brit., pi. xliv. 

 ,, Milne-Edwards, Hist. Nat. Crust., torn. ii. p. 3G5. 



Dorsal surface of the carapace without a carina ; anteriorly produced to a rostrum, 

 not laterally compressed ; orbital margin furnished with a supraorbital tooth. 



Pleon smooth and gradually tapering. 



Ophthalmopoda short, scarcely reaching beyond the frontal margin of the carapace. 



First pair of antenna? having a long stylocerite, and terminating in two flagella, of 

 which the upper is unequally biramose. 



Second pair long, slender, and carrying a long ovate scaphocerite, armed with a distal 

 external tooth. 



Mandible furnished with a two-jointed synaphipod. 



Second pair of gnathopoda pediform, five-jointed, robust. 



First pair of pereiopoda subequal, symmetrical, robust, chelate. Second pair multi- 

 articulate, minutely chelate. Three succeeding pairs simple. 



Rhipidura well developed. 



Telson dorsally flat and laterally tapering. 



Geographical Distribution. — European Shores and Cape Verde Islands. 



Hitherto the genus has been represented only by one species, and that sparingly 

 taken on the coasts of England and Norway. On the coasts of Devon and Dorset, 

 and the Channel Islands, it has been taken occasionally and sometimes abundantly, and 

 Sars records it from Christiania Fjord in Norway. I am not aware of its having been 

 previously taken elsewhere, but the new form, Athanas veloculus, was captured off the 

 Cape Verde Islands by the Challenger. 



