Chilton. — Some New Zealand Amphipoda. 231 



C. bonellii M.-Edw. It is evidently a difficult question, and probably will 

 not be thoroughly settled till we know more of the life -history and sexual 

 differences of these animals. The latest discussion with which I am 

 acquainted is given in a paper by Walker (1914, p. 559), where he points 

 out that C. acherusicum Costa is a synonym of G. bonellii, and in which he 

 regards this species as distinct from C. crassicome Bruz. He had previously 

 (1909, p. 343) recorded C. bonellii from the Indian Ocean, but at that time 

 had evidently been in considerable doubt about the identification, for in 

 the copy of his paper forwarded to me he had altered the printed name 

 G. bonellii to G. crassicome. In 1914 he says the name G. bonellii should 

 be left as printed. 



I shall content myself with a statement of the facts of the New Zealand 

 species as they appear to me. The male specimens have the very large 

 stout second antennae corresponding precisely with the figures given by 

 Sars for C. crassicome Bruz., and in other points the animals appear to 

 agree closely with his description and figures except for the slight differ- 

 ence in the third uropod which is mentioned below. The female specimens 

 also seem to agree closely with the description he gives for the female of 

 C. crassicome, though there appears to be some variation in the second 

 antenna, the number of spines on which does not always agree precisely 

 with the figure, and in some specimens these appendages agree more closely 

 with his figure of C. bonellii. These two forms have been constantly found 

 together in New Zealand, and I feel certain that they must be looked upon 

 as male and female of the one species. Doubtless, as in other species, the 

 adult characters of the second antenna in the male are only gradually 

 attained, and the immature stages more or less closely resemble the female 

 form. In an attempt to settle the question I got specimens some years 

 ago, through the kindness of Mrs. Sexton, Plymouth, from the Dutch 

 coast, sent by Dr. Hoek as *' C. crassicome,''' and others from the laboratory 

 at Plymouth labelled " G. bonellii.'''' The Plymouth specimens were appa- 

 rently all females — at any rate, I have not found an adult male among 

 them ; but those from the Dutch coast contained both males and females, 

 the males agreeing closely with Sars's description of C. crassicome. After 

 careful comparison of both sexes of these specimens with the New Zealand 

 forms I have failed to distinguish any character that I consider of specific 

 importance, and I am therefore labelling and recording the New Zealand 

 specimens as C. crassicome Bruz. I have also specimens from Port Jackson, 

 New South Wales, agreeing minutely with the New Zealand forms. 



Sars says that that C. bonellii is distinguished by (1) the absence of a 

 rostrum, (2) the rounded lateral angle of the head (not sharply acute as in 

 C. crassicorne). and (3) the character of the second antenna of the female. 

 In all the specimens that I have examined for this particular point — viz., from 

 New Zealand, "C. crassicome" from the Dutch coast, and "C. bonellii" 

 from Plymouth — the rostrum is present. The lateral angle of the head is, 

 as Walker states, difficult to see, but as far as I can make out it varies, in 

 some cases being somewhat rounded, as described by Sars for C. bonellii, 

 and in others more acute. With regard to the third point, as already 

 stated, I find considerable variation in the antennae of the females, and the 

 New Zealand forms agree, some with the figure given by Sars for C. crassi- 

 come, others with that for C. bonellii. 



The only point in which the New Zealand specimens differ from the 

 European ones that I have examined appears to be in the third uropods, 

 which are slightly broader both in the peduncle and in the ramus, and have 

 the two rami usually directed slightly towards the median line, instead of 



