Mr. A. O. Walker on Pherusa fucicola {Leach). 419 



seems "very near to Pherusa fucicola ; but if the figure given 

 by the authors " — he does not say what authors — " is exact, 

 ours differs from it by the first two pair of feet being equally 

 small." These had been previously described as " filiform." 

 He also says of the abdominal segments, " furnished on the 

 back with a short and delicate spine near the base of the 

 fifth segment, and another on the posterior margin of the 

 sixth observable when highly magnified." 



In 1862 Spence Bate ('Catalogue of the Specimens of 

 Amphipodous Crustacea in the British Museum,' p. 145, 

 pi. xxvii. fig. 10 [not fig. 9, as stated both in text and plate]) 

 describes P. fucicola, Leach. He had previously stated that 

 the genus Pherusa differs from A tylus only in having an entire 

 instead of a cleft telson. He refers to this species Amphithoe 

 Jurinii, M.-Edw., and A. fucicola. Leach (Milne-Edwards, 

 Ann. des Sci. Nat. 1830,' vol. xx. pp. 376, 377), notwith- 

 standing that this author makes these two species quite 

 distinct. Spence Bate also refers A. microura, Costa (v. 

 supra), to A. fucicola, from which, however, it differs in the 

 antenna?, the peduncles of both pair in Costa's species being 

 very much longer in proportion to the flagella than in A. 

 fucicola as described by Spence Bate, and in the last three 

 pleon-segments, which appear to be extremely short in A. 

 microura, while they are figured as somewhat long in Bate's 

 figure. 



We have therefore apparently here three distinct species 

 referred to Pherusa fucicola, Leach, of which only one, A. 

 Jurinii, M.-Edw., seems at all to agree with Spence Bate's 

 description and figure. 



In 1862 Spence Bate and Westwood published part 6 of 

 the ' British Sessile- eyed Crustacea.' At p. 252 they repeat 

 Bate's statement that the " chief distinction between Pherusa 

 and Atylus^ is the "entire central caudal plate" in the 

 former genus. At p. 255 they describe and figure P. fucicola, 

 Leach, " from the typical specimen of Dr. Leach in the 

 British Museum." They admit that it "differs from the 

 figure given in the ' Catalogue of Amphipoda in the British 

 Museum' in a few details, the most important of which are 

 the length of the last pair of caudal appendages and the length 

 of the inferior antennas." They omit to mention that the 

 telson, as figured by them, is deeply cleft, and that conse- 

 quently the typical species of Leach's genus Pherusa cannot 

 belong to that genus as defined by Spence Bate and them- 

 selves. 



By the courtesy of the authorities of the British Museum I 

 have been able to make as careful an examination of the 



