RHODALIIDAE. 315 



It seems that the difficulty of reconcihng the homology of aurophore with 

 pneumatochone if the former occupied a dorsal position was largely instrumental 

 in leading to their conclusion. Had it not been for this consideration, they 

 would hardly have assumed that the aurophore was the zone of proliferation 

 in Archangelopsis, merely on the grounds that it bore papillae, and that no buds 

 of either nectophores or siphons were to be found on the opposite side of the 

 corms in their ver>- fragmentary specimens, although they found no stages 

 connecting the simple and very uniform papillae of the aurophore with the 

 complex cormidia lying below. The actual evidence to which they had access 

 was entirely of a negative kind. Nor can any more weight be laid on their 

 observation that no buds are now to be found opposite the aurophoi-e in the 

 "Challenger" specimens of Rhodalia, because the latter were somewhat frag- 

 mentary to start with, and by now have passed through so many hands that 

 any buds which were originally attached might well have been torn or shaken 

 off. However, we must admit that in view of the usual dorsoventral orienta- 

 tion, and of the frequent inaccuracies of Haeckel's work, their standpoint was 

 perhaps the most reasonable one. Simple and attractive as was their explana- 

 tion that new nectophores and cormidia are formed on the aurophore itself, 

 the conditions in Dromalia, in Angelopsis and in the excellent example of Archan- 

 gelopsis mentioned (p. 303) show beyond any question that it is the exact reverse 

 of the truth. And if we compare the photographs of the ventral zone of pro- 

 liferation in Dromalia (Plate 24, fig. 1, 2) with Haeckel's figures of a longitudinal 

 section and an apical view of Rhodalia, and his figure of the blastocrene 

 ('88b, pi. 4, figs. 15, 16, 17), it is evident that they are very accurate. I may 

 mention that the figure of the blastocrene clearly shows that the cormidia are 

 arranged in spiral, exactly as they are in Dromalia. On Haeckel's figure of an 

 apical view, with the nectophores in place ('88b, Plate 1, fig. 1), Schneider 

 ('98) and Lens and Van Riemsdijk thought they could discern internal evidence 

 that the young nectophores were budded on the same side as the aurophore. 

 But, as Haeckel himself states ('88b, p. 303), it is a reconstruction; and even if 

 the arrangement of the nectophores, as represented, is correct, it is not necessary 

 to assume that the small ones near the aurophore are the youngest. On the 

 contrary, the fact that the nectophores in this region are smaller than their 

 neighbors in Dromalia, as shown by the shortness of their muscle-plates (p. 307), 

 whereas proliferation undoubtedly takes place on the opposite side of the corni, 

 indicates that in Rhodalia likewise, those nearest the aurophore are the oldest 

 instead of the j'oungest, although small. 



