28 "TERRA NOVA" EXPEDITION. 



Remarhs. — Prof. Bouvier, taking liis measurements apparently from Mr. Hodgson's 

 figures, concludes that tlie " Discovery " specimens differ from those of the " Frangais " 

 and " Pourquoi Pas ? " in the greater relative thickness of the neck and in some other 

 characters of less importance ; and he suggests, tentatively, that the species may be 

 divided into two geographical races, the "forme laticoUe" inhabiting the Australian 

 province, and the " forme angusticoUe " the Magellanic province of the Antarctic region. 

 In the former the ratio between the width of the cephalon anteriorly and that of the 

 neck is represented by the number 1'56, while in the latter it varies from 2*5 to 3-0. 

 The actual specimens from which Mr. Hodgson's figures were drawn cannot now be 

 identified, but it is very unlikely that the accuracy of the figures themselves is so great 

 as Prof Bouvier assumes it to be. In half a dozen specimens taken at random from 

 among the syntypes of the species, I find the ratio to vary between 2*55 and 2 "77, 

 while a close scrutiny, without actual measurement, of the remaining syntypes as well 

 as of the material obtained by the " Terra Nova " failed to reveal any conspicuously 

 thick-necked individuals such as would correspond to a ratio of 1*56. It is, at all 

 events, clear that the slender-necked form is by no means restricted to the Magellanic 

 province, while the thick-necked form, if it exists at all, is in no way characteristic of 

 the Australian province. 



Both Hodgson and Bouvier comment on the difficulty or impossibility of 

 perceiving the genital pores in many specimens of the male sex. This is the case 

 also with most of the specimens that I assume to be males in the present collection, 

 but in several ovigerous specimens they are visible on the legs of the last three pairs, 

 as Hodgson states. Bouvier makes the very probable suggestion (previously made 

 by Hoek in the case of Boreonymphon robustum) that the pores only appear at the 

 breeding period. In the ovigerous males and in some others which, from their size, 

 are probably approaching maturity, the ventral surface of the femur bears a series of 

 about ten low, truncated tubercles, bearing the openings of the femoral glands. 



In one specimen more transparent than the rest (perhaps from a recent moult) 

 the general arrangement of the nervous system can be made out. There are six large • 

 ganglia in the ventral chain, each of them lying within the limits of the somite 

 innervated by it, with the exception of the last, which is moved forwards into the 

 penultimate somite. 



Genus NYMPHON, Fabricius. 



Although several writers (e.g., Meinert, 1899, p. 34) have commented on the 

 indefinite character of the genus Chcetonymphon, Sars, it is still retained as a valid 

 genus by Prof. Bouvier in his latest memoir (1913, p. 94). I am encouraged to depart 

 from this precedent, however, by the fact that Prof Bouvier himself seems to have 

 been misled by it, and to have described as a new species of Nymphon a form that 

 had already been twice named and described in the genus Chcetonymphon (see below, 

 N. australe). 



