SYSTEMATIC AND BIOLOGICAL ACCOUNT 95 



Amphicaryon. The first A. acaule, has been well figured by Bigelow (191 ib, pi. 4). The reduced 

 nectophore is embraced by the larger one, and its atrophied nectosac has the characteristic shape 

 illustrated by Bigelow. Its closed entrance is in contact with the surface, and its four radial canals 

 are distinct. The upper parts of the lateral-radial canals of the larger nectophore are simple and not 

 branched as in ernesti and peltifera. 



In the second, a new species, to which I give the name ernesti, 1 the smaller nectophore is not partially 

 enclosed by the larger one, whose lateral radial canals are branched in the basal region, and the 

 entrance to its atrophied nectosac lies at some distance from the surface, but is connected by a fine 

 strand of tissue. Its ventral radial canal becomes a network covering the ventral wall, and its lateral 

 canals disappear and leave only the dorsal canal. These differences in the radial canals appear to be 

 constant. The whole arrangement is often difficult to see, and sometimes looks rather like Haeckel's 

 figure (1888 a, p. xxviii, fig. 2) of Mitrophyes peltifera. For years I thought it must be M. peltifera, 

 but in March 1952 I found (in a haul from 'William Scoresby' Station 459) an Amphicaryon specimen 

 that is different from both acaule and ernesti, but closely resembles Haeckel's fig. 2 of Mitrophyes 

 peltifera. All the radial canals of its larger nectophores are simple. In its shield-shaped second 

 nectophore, whose outer wall is concave, can be clearly seen, on the ventral side, a three-branched 

 canal, but there is no sign of a nectosac. Some days later I found two other exactly similar specimens 

 in plankton from 'Discovery II' Station 1580, TYF B, 450-0 m. I feel hopeful, therefore, that one 

 day more material of Haeckel's species will come to hand. Bigelow (1918) reported 30 specimens of 

 ' A. acaule ' from the W. Atlantic. But they differ from that species as here recognized and agree with 

 this new species in two of the main characters: (1) the smaller nectophore is not enclosed by the larger; 

 (2) the lateral radial canals are branched. I suspect that he was dealing with A. ernesti. 



A fourth, new, giant Amphicaryonine species from the West Coast of Africa is described below. 

 Both its nectosacs are functional. 



The eudoxid described by Leloup (1934a) as Eudoxia tottoni is the eudoxid of a species of Amphi- 

 caryon, probably A. acaule. 



Material. 'Discovery II' Station 2648, 500-0 m. (Text-fig. 44, type specimen); Station 698, 

 470-0 m., 2 'larger' nects.; Station 702, 230-0 m., 4 ex., 1 larger nect. ; Station 1374, 230-0 m., 

 1 ex., 1 'larger', 1 'smaller' nectophore; Station 1584, 100-50 m., 1 larva, 175 mm. in length (Text- 

 fig. 45) Station 2679, 2 ex. 



The larva is the first, as far as I know, of any species of Amphicaryon to be recorded. The lateral 

 radial canals are similar to those of ernesti and are not simple as in acaule. The larval nectosac is similar 

 in shape to that of the 'larger' of the adult nectophores. The pedicular canal is so short that it has 

 almost disappeared. I think that the 'larger' nectophore in species of Amphicaryon must be the 

 persistent larval one, and that it is not caducous as it is in Rosacea. A slightly older larva of Amphi- 

 caryon acaule from 'Discovery II' Station 1583 (550-250 m.) also shows the bud of the smaller 

 (obsolescent) definitive nectophore growing out from the spot marked N 2 B in Text-fig. 45 A. On the 

 side of the central organ opposite to this bud, both larvae show the budding zone of gastrozooids. 

 Both also show the median growing apex of the pallial canal or somatocyst, XB. Two other larvae of 

 A. acaule from ' Discovery II ' Station 1581 (600-0 m.) show quite clearly that the first nectophore bud 

 becomes the obsolescent nectophore of the adult, and that the ' larger ' nectophore of the adult is the 

 persistent larval nectophore. 



1 In honour of my esteemed colleague Ernest White, who has given me invaluable assistance in all my work since 1918, 

 and who has undertaken so much of the routine work involved in examining thousands of plankton samples and in sorting and 

 curating enormous siphonophore collections. I have to thank him for very great assistance in preparing and checking the text 

 of this report. 



