230 Transactions 



of the whole animal. Shortly after this I collected in Lyttelton Harbour 

 specimens that agreed with the description given by Mr. Thomson, and I 

 therefore identified them as C. contractum. At the same time, and in 

 association with these specimens, I collected others similar in most characters 

 but differing in the form of the second antenna. These specimens appeared 

 to be closely similar to the descriptions and figures given of C. crassi- 

 come Bruz. in Spence Bate's Catalogue of the Amphipoda in the British 

 Museum and in Bate and Westwood's British Sessile-eyed Crustacea, and 

 were accordingly named C. crassicome. Since the specimens identified as 

 C. crassicome were associated with those identified as C. contractum and 

 apparently were males — at any rate, not bearing eggs — I concluded from the 

 general resemblance between the two that they were male and female 

 of the one species. As C. crassicome was recorded from Europe, I looked 

 up the works mentioned above to see if there was any mention of a form 

 similar to C. contractum to represent the female of C. crassicome in Europe, 

 and found that C. bonellii Milne-Edwards appeared to be very similar to 

 the New Zealand specimens I had identified as C. contractum, and I con- 

 cluded therefore that it was probably the female of C. crassicome. On 

 writing to the Rev. T. R. R. Stebbing asking for information as to whether 

 this conclusion was correct or not, he replied that some authorities con- 

 sidered C. crassicome and C. bonellii to be male and female of the one 

 species, while others, including Sars, considered them as distinct species. 



In view of this difference of opinion, and in the absence of specimens 

 from Europe, or sufficiently detailed descriptions to investigate the matter 

 fully, the question was for the time left an open* one, and in the list 

 of the Crustacea Malacostraca of New Zealand, published in 1896 by 

 Mr. G. M. Thomson and myself, the two species C. contractum Stimpson 

 and C. crassicome, Bruz. were included with the following note after the 

 last-named : " This species is taken along with C. contractum, and it 

 is probable that they are only male and female of the same species. 

 C. bonellii (Milne-Edwards) is probably the same as C. contractum. — C. C." 

 (1886, p. 142). 



For various reasons I was unable to give further attention to this 

 particular question for many years, though on several occasions when 

 specimens of Corophium were collected at different parts of the New Zea- 

 land coast both forms — i.e., " C. contractum Stimpson " and " C. crassi- 

 come Bruz." — were taken together, thus fully confirming my opinion that 

 these were male and female of the same species, whatever might be the 

 case with the C. crassicome Bruz. and C. bonellii in Europe. 



In the meantime many important works on the Amphipoda have been 

 published which contain more or less direct evidence on the point at issue : 

 e.g., Sars in his great work on the Amphipoda of Norway in 1894 still 

 keeps the two species separate, and describes forms which he considers to 

 be male and female of C. crassicome, the female form being different from 

 the specimens which he refers to C. bonellii. Of this latter species he 

 describes no male, saying, " It is very strange that I have never met with 

 males of this form, though I have collected the species in several different 

 places. Perhaps the sexual difference is so very slight as to escape atten- 

 tion " (1894, p. 617). In Das Tierreich Amphipoda, Stebbing (1906, p. 690), 

 apparently following Sars, describes male and female forms of C. crassi- 

 come, and considers C. bonellii a separate species, of which only the female 

 is known. 



I do not propose to go into the history of the various opinions that 

 have been expressed as to the relation of C. crassicome Bruz. and 



