Mr. R. I. Pocock on Pherusa fucicola, Leach. 531 



Omitting most of the synonyms, which for my present 

 purpose are of no importance, the history of the genus and 

 species may he briefly told as follows : — 



It was first described in 1814* by Leach in the appendix 

 to the article " Crustaceology " of the Edinb. Encycl., and 

 subsequently, but not in the same terms, in the Trans. Linn. 

 Soc. for the following year. 



In 1830, in the Ann. Sci. Nat., Milne-Edwards described 



two species of Amphipoda — one named Amphithoe Jurinei 



and the other Gammarus (now Gammarella) brevicaudatus (a) 



— this last being, as Mr. Walker has shown, Leach's Ph. 



fucicola. 



In 1862, in the Cat. Amphipoda of the Brit. Mus., Spence 

 Bate wrongly described as Ph. fucicola, Leach, a species 

 identical with Amphithoe Jurinei, M.-Edw., giving Amphi- 

 thoe Jurinei, M.-Edw., as a synonym of it. In the same 

 volume he also redescribed Gammarella brevicaudata, but of 

 course without discovering that it was Leach's Ph. fucicola. 



In 1863 f, iu vol. i. of the Brit. Sessile-eyed Crust., Bate, 

 in conjunction with Westwood, again describes P. fucicola ; 

 but on this occasion he characterizes, although not accurately, 

 the right species, and gives a figure, although an inaccurate 

 one, of Leach's type specimen. He does not discover, how- 

 ever, that his Ph. fucicola of 1863 is different from his Ph. 

 fucicola of 1862. 



To these errors committed by Spence Bate may be traced 

 the synonymical labyrinth through which Mr. Walker has 

 so skilfully and carefully brought us. But after trustfully 

 following him so far, I sincerely regret that at this point we 

 must part company. He prefers to follow a by-path which I 

 am convinced will ultimately involve him and his followers 

 in a maze, if possible, greater than that from which he has 

 just escaped ; while 1 am compelled to keep to the road along 

 which the law of priority points — a law which is to me as a 

 law of the Medes and Persians. Fortunately, owing to Mr. 

 Walker's safe guidance, the road ahead is perfectly obvious, 

 and leads inevitably to the following conclusions : — (1) That 

 Pherusa fucicola of Leach, 1814 |, and of Bate, 1863, must 



* Without going into the matter, I follow Mr. Stebbing in his opinion 

 as to the date of this work. 



t This is the date that the Museum copy of this work bears. I here 

 use the dates to designate the differeut works, irrespective of the dates of 

 publication of the separate parts of the 'Sessile-eyed Crustacea.' 



J I am thus particular with the date because of the possibility of its 

 ever being suggested that the P. fucicola of the Linn. Trans. (1815) may 

 be different from the one described in the Encycl. of 1814. Such a 

 suggestion, it seems to me, would not be altogether unreasonable, for the 



