232 Transactions. 



projecting directly backwards as shown by Sars for C. crassicorne. The 

 difference is, however, not great, although it is easy to make considerable 

 difference in the figure, and the general appearance of the end of the pleon 

 is very near to that figured by Sars for C. bonellii.* 



Although the fully adult males and females in this species appear to be 

 readily distinguished from one another by the characters of the second 

 antenna, it is probable that the sexual relations are not always quite so 

 simple. For example, I have a specimen, now mounted permanently as 

 a micro-slide, in which the second antennae are stout and have on the under- 

 surface a stout tooth which corresponds to the tooth found in the adult 

 male, though not so pronounced ; this specimen I should without hesita- 

 tion consider as an immature male, but unfortunately on the appendages 

 of the peraeon there are brood-pouches similar to those in the female. In 

 the two species C. spinicome Stimpson and C. salmonis Stimpson from 

 the Pacific, which were redescribed in 1908 by Bradley, the adult females, 

 as figured by him, have the characters of the second antennae of the adult 

 male, though these are not developed to quite the same extent. 



It is well known that C. crassicorne, like other species of the genus, is 

 frequently found in brackish and sometimes even in perfectly fresh water. 

 As far as I am aware, the New Zealand species has been taken in salt water 

 only, though the allied form Paracorophium excavaturn Thomson is found 

 in brackish and fresh water. Stebbing has described from the brackish 

 water of Lake Negombo, in Ceylon, a species, C. triaeonyx, winch appears 

 to me to be very close to the New Zealand forms, but differs in having 

 the third uropods much less broadened. Similarly, in 1912, Wundsch 

 described C. devium from fresh water near Berlin, a species which, from 

 his figures, seems to agree very closely with Stebbing's species in the 

 characters of the terminal uropods. 



* Stebbing (1914, p. 372) records Corophium cylindricus (Say) from the Falkland 

 Islands, saying, " The figures and description of the female supplied by Dr. S. J. 

 Holmes leave no doubt that Mr. Vallentin's specimens belong to this species." He 

 quotes C. cylindricus Paulmier (1905, p. 167, fig. 37) as a synonym, and suggests that 

 C. quadriceps Dana (2 mm. long) from Rio de Janeiro, and C. contractum Stimpson, 

 1855, from Japan, and the specimens from New Zealand recorded under this name 

 by G. M. Thomson also belong to the same species. He gives no description of the 

 Falkland Islands specimens except that they measure only 3 mm., as compared with 

 3-4 mm. given by Holmes, and 5 mm. by Paulmier, " probably with reference to a 

 male specimen which he figures in full." I agree with Stebbing that the Falkland 

 Island specimens are probably the same as those from New Zealand, but I do not know 

 why he assigns them to C. cylindricus rather than to C. crassicorne. In Das Tierreich 

 Amphipoda (1906, p. 692) he classes C. cylindricus among the "obscure" species, but 

 in the appendix (p. 740) gives references to the description and figures given by 

 Paulmier and Holmes. 



I can find nothing in Holmes's description and figures inconsistent with the suppo- 

 sition that the species he describes is the same as the European 0. crassicorne, and 

 certainly the figures he gives of the second antenna both of male and female apply 

 well to the New Zealand forms that I have referred to C. crassicorne. Similarly, the 

 description and the figure of the male given by Paulmier apply equally well to the 

 New Zealand forms. Neither Paulmier nor Holmes makes any reference to or com- 

 parison with other species. 



Barnard (1916, p. 272) records C. acherusicum Costa from Durban Bay. Stebbing 

 (1906, p. 692) give this species among the "obscure" species, with the remark, 

 " perhaps identical with C. boneim." Walker (1914, p. 559), after comparing specimens 

 of each, definitely united C acherusicum with the older C. bonellii, to which he also 

 referred C. crassicorne Hoeck (1879, p. 115). 



It seems to me that these facts, which I had not paid special attention to when 

 writing the remarks given above, show that all the forms to which these varied names 

 have been given are so alike that they cannot be distinguished even by experts, and 

 the conclusion I had alreadv come to in the text receives additional confirmation. 



