ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 465 



usual three) on each side of the genital cleft ; the palps with a long stiflf 

 bristle on the flexor edge of the second segment. The author also de- 

 scribes Eylais zviJsonlsYi.B., from near Staines. Each eye-capsule stands 

 isolated on the skin without any connecting bridge, as in other species 

 of the genus. 



e. Crustacea. 



Nerve Fibres of Crustacea.* — J. Nageotte finds that all the nerve 

 fibres in Mysis, Palsemon, and Crangon are medullated except those to 

 blood-vessels and intestine. The fibres are ribbon-like in section. The 

 myelin sheath is unbroken from beginning to end, but thinner at 

 Ranvier's nodes. 



Question of Species among Amphipods of the Genus Ampelisca.f 

 Chas. Chilton discusses with thorouglmess the species of Ampelisca, and 

 in particular the identity of A. eschriclitii Kroyer and A. macrocephala 

 Liljeborg. These and some other species are to be referred to A. 

 eschrichtiiKvojer, which is widely distributed both in Arctic and Antarctic 

 seas, is most abundant and biggest in high latitudes, but also extends 

 into low latitudes in both hemispheres, and in so doing may develop to 

 sexual maturity while of smaller size. In these smaller specimens some 

 of the characters are less marked, but no constant association of charac- 

 ters can be found warranting the establishment of distinct species. It 

 is probable that this case is typical of that of many marine Amphipods. 



Distribution of Amphipods. | — Chas. Chilton discusses the distribu- 

 tion of Elasmopus rapax A. Costa and Msera insequipes (A. Costa). The 

 former has been recorded as widely distributed — in the North Atlantic, 

 Mediterranean, Indian Ocean. Chilton finds that it occurs also in 

 Australian Seas, and Walker has recorded it from Rio de Janeiro and 

 from Arica, Chile. Similarly, Msera insequipes occurs widely in 

 Southern as well as in Northern Seas, having a distribution practicully 

 identical with that of Elasmopus rapax. 



Sex Dimorphism in Hyale.§ — Chas. Chilton finds that the male of 

 a New Zealand Amphipod, ffyale grenfelU Chilton, is marked by the 

 great dilatation and setose character of the terminal joints of the 

 maxillipeds. The maxilliped in the female presents the ordinary char- 

 acters common to allied species of Hyale, and its terminal joints show 

 none of the numerous transverse rows of long fine setffi on the surface 

 that are so characteristic of the male. There are also some slight sex 

 differences in the gnathopods. 



* G.R. Soc. Biol. Paris, Ixxix. (1916) pp. 259-63. See Physiol. Abstracts, i. 

 (1916) Nos. 5-6, p. 209. 



t Journ. Zool. Research, ii. (1917) pp. 75-9.3 (7 figs.). 



X Journ. Zool. Research, ii. (1917) pp. 17-19. 



§ Ann. Mag. Nat. Hist., xix. (1917) pp. 273-6 (3 figs.). 



Oct. 17th, 1917 2 I 



