46 DISCOVERY REPORTS 



siphosome bears a great resemblance to that in Physophora, and forms a pointed outgrowth (Text- 

 fig- 3)- 



As Haeckel truly stated, the gonodendra develop on meridians between those on which the 



gastrozooids are found, but on their apical side. Haeckel's figure, on the contrary, would give the 

 impression that successive groups of palpon, gonodendron and gastrozooid were each borne on one 

 meridian. 



The whole arrangement of the cormidia is very like that found in Rhodaliids, but whereas the 

 nectophores, in that family, form a bilateral corona, in Physophora the budding zone of the nectophores 

 is carried up in an apical direction. Whether their muscular lamellae are all attached to a single 

 meridian or not needs further, careful determination. Successive lamellae overlap one another, but 

 the pedicular canals may lie in one meridian. Physophora is a highly specialized form, and it is unlikely 

 that its larva would tell one much about its phylogeny. I agree with Garstang in thinking that there 

 is no reason why it should ever have had a macrostele ancestor. On the other hand the elongation 

 of the proximal part of the protosiphon of one of its ancestors conceivably might have given rise to 

 a macrostele type of Physonect. ■ 



'Stephanomia' 

 No one can be sure at present what is the identity of a siphosome originally figured by Lesueur 

 & Petit (1807-1 1, Atlas) which they called Stephanomia amphytridis . Peron (1807-16) did not mention 

 it by name in his text (Tome 1, p. 45) but gave a short description of the living siphosome, its feeding 

 habits, its phosphorescence, and a reference to Lesueur's and Petit's figure. Strictly speaking, then, 

 the name was published by Lesueur & Petit. I have found in Peron's text no clue as to where it was 

 taken — Bigelow (191 1 b, p. 288) said, 'in the Atlantic' — but in Peron's narrative it was mentioned 

 after that part of the text which dealt with arrival at He de France. It might, therefore, have been 

 taken anywhere between Le Havre and Mauritius. 



There are two courses open to systematists when dealing with this name and with long-stemmed 

 Physonects that have single terminal filaments to their tentilla. The first is to use the name 

 ' Stephanomia ' as a temporary convenience and to acknowledge that S. amphytridis of Lesueur & Petit 

 is at present unidentifiable ; and therefore cannot be the name of the type of a genus Stephanomia. 



The second course is to abandon the generic name Stephanomia and to take instead one that can be 

 used for a species of which topotype specimens, or a type specimen, can be re-examined — specimens, 

 that is, of a long-stemmed form with single terminal filaments. 



For the present I am taking the first course, but I am excluding and placing in a new genus named 

 after Mr J. W. S. Marr three species found chiefly in the Arctic and Antarctic. In the present state 

 of our knowledge, I think it would be unwise to attempt to identify specimens of 'Stephanomia' 

 (sensu Bigelow) unless they bear nectophores, for nectophores do, I believe, have constant specific 

 characters which establish their identity. Lesueur's, Huxley's and Bigelow's famous specimens of 

 Stephanomia lacked the nectosome, and no nectophores have even been described under the name 

 of amphytridis or amphitridis. Indeed, there are few proper descriptions of the nectophores of any 

 species of ' Stephanomia '. Different species of Physonects may have nectophores that are superficially 

 alike, so great care must be taken with their identification. It is generally necessary to stain 1 both the 

 radial canals and the ridges. Figures of nectophores published long ago are not, as a rule, to be relied 

 upon. 



I recommend the use of very dilute borax-carmine for the canals, and of Delafield's haematoxylin for ridges. (See p. 10.) 



