62 DISCOVERY REPORTS 



lateral radial canals, however, is not very good. My new drawing of the nectophore (Text-fig. 24) 

 is still not quite satisfactory. 



From 'Discovery II' (East African line) Stations 1567, 1568, 1581, 1583, 1584, 1586 and 1587 come 

 larvae with bracts typical of larvae thought to be those of this species. These bracts are identical in 

 shape with those of larvae taken with adult specimens in the Celtic Sea, and also with those of a series 

 of post larvae taken by 'Scotia' and kindly sent by Dr J. H. Fraser of Aberdeen. A study of the 

 ' Scotia ' specimens has enabled me to say that the well-known larval Agalmid stage (see Haeckel, 

 18886; pi. xxi, fig. 12) in which larval bracts cover the air-sac and all buds, is followed by one in 

 which the nectosome elongates and emerges from the whorl of larval bracts. The last of these, however, 

 remain for a time attached by their muscular lamellae to their supporting prominence, and have been 

 found in specimens 3 or 4 mm. in length, after the appearance of a second functional gastrozooid, and 

 even in the terminal cormidium of a specimen 7 cm. in length. The buds of the nectophores now grow 

 and begin to function. There is a second smaller gastrozooid and a ring of from four to eight palpons 

 present at this stage, which is prior to the elongation of the siphosome in the reverse direction to that 

 of the nectosome and to the appearance of a succession of secondary stem groups of buds. The stage 

 before the appearance of secondary groups is reminiscent of the adult Nectalia loligo, and might be 

 referred to as the ' Nectalia-stage ' in the same way in which earlier stages are referred to as ' Athorybia- 

 larvae ' because of their resemblance to miniature specimens of Athorybia rosacea. In the ' Nectalia- 

 stage ' the terminal gastrozooids are surrounded, just as they are in Nectalia, by a number of long, 

 trifid bracts of the general shape figured by Haeckel (18886; pi. xm, figs. 1, 9-12). They are very much 

 like those of Athorybia rosacea and, since they are probably pre-cormidial as Garstang suggested, they 

 may be homologous with them and with the larval bracts of A. okenii. It remains to work out in 

 Agalma elegans the succession of bracteal types and their situation on the stem. 



A slightly later stage at which four or five nectophores are functional, is represented by a series of 

 beautiful specimens taken at 09.15 hr. at Villefranche on 28 March 1949 near the surface in a i-m. net. 

 In these, the larger of the two terminal gastrozooids described above for the ' Nectalia-stage ' bears 

 an adult-type tentacle (but with only two turns of the cnidoband, and the involucrum either covering 

 it completely or only partially on one and the same tentacle), whilst the smaller one bears a tentacle 

 with kidney-shaped (larval-type) tentilla. 



If anyone was able to devote the spring of a year like 1949, when Agalma elegans was abundant at 

 Villefranche, to watching the development of this species he would, I think, be able to confirm that 

 in the course of its life-history it passed through successive stages reminiscent of Athorybia, Melophysa 

 and Nectalia 1 and would therefore come to the conclusion that species of these genera have become 

 neotenic at successively later evolutionary stages. 



I take this opportunity of publishing the following data for a live specimen 12 cm. in length, taken 

 at Villefranche on 14 April 1949. Nectosome: 3-5 cm. long, 1 cm. diameter; ten nectophores on one 

 side and nine on the other, and buds. Siphosome: three complete gastrozooids, one young one. 

 Gastrozooids 5 cm. apart. The terminal gastrozooid was surrounded by a ring of palpons. But the 

 tentacle of one ' palpon ' bore larval type tentilla so that it was probably the secondary gastrozooid. 

 The rest had ordinary thread-like tentacles. The terminal gastrozooid bore a typical tentacle 12 cm. 



1 Nectalia Haeckel, 18886, should be accepted with some caution, since specimens with the very peculiar tentilla that 

 Haeckel figured have not certainly been seen again, and his figures are often not dependable. Bigelow's (191 1 b, pi. 20, figs. 4, 5) 

 specimen may be a young stage of a long-stemmed form. I have examined many such specimens taken at Bermuda by Beebe, 

 but a great deal more work has still to be done on the large amount of Agalmid material sent me by Beebe before the question 

 can be resolved. I hope eventually to be able to link up these Nectalia-like specimens with a giant form that I provisionally 

 called Stephanomia amphitridis. They have a new type of nectophore. 



