148 
G. HERBERT FOWLER. 
is proportionately much more considerable than in the larger 
specimen. 
No generative organs occurred in either of the three 
examples. 
It is a matter of regret that this new morphological type 
does not throw any fresh light on the obscure phylogenetic 
relationship of the various tribes of Actinaria to each other. 
Doubtless the non-fixation (cf. the primitive Halcampae) and 
persistent biconvex shape of the polyp indicate a condition 
more or less ancestral, while from the ectodermal, longitudinal 
(radial) muscle, which characterises hydroid-polyps and Scy- 
phostomse, Prof. R. Hertwig would infer a very close relation 
with the Hydrozoa, a conclusion which is certainly strengthened 
by the shape of the body. A study of the structure of the 
animal certainly does not suggest that it is a highly modified 
form derived from representatives of the existing Hexactinian 
type, but rather that it is collaterally descended from an ancestor 
represented by the somewhat flattened larva of modern Antho- 
zoan embryology, with no distant kinship to the Hydrozoa. 
From existing forms, Thaumactis is marked off by the pseudo- 
tentacles, the method of retraction, the abnormality of the 
directive mesenteries, the biconvex shape, and the ectodermal 
radial musculature ; and may possibly stand as type of a new 
tribe, the Thaumactinise. 
Phialactis neglecta, gen. sp. nn. 
Of this new Actinian, two broken examples were found in the 
same bottle with the Thaumactis described above, attached to 
pieces of Millepora sp. from the Papeete Reefs. Its claim to 
interest lies in the fact that it affords a further example of that 
retrogression of the tentacles, of which the only known 
examples are four genera of Hexactinise, and two Paractinia?, 
all occurring among the deep-sea “ Challenger ” Actiniaria 
described so ably by Prof. R. Hertwig. From these, how- 
ever, this new genus differs in the fact that the tentacles are 
replaced, not by stomidia — slight elevations of the oral disc, 
surrounding a large opening which is homologous with the 
