17 Gce l 
CCELENTERA'l'A. 
as residua of the original cavity, when the rest is filled up by the inward 
growth of the ectoderm, pushing before it the hyaline membrane and the 
endoderm — a fact which, in certain senses, modifies the morphological 
conception of the homology between “ polype ” and “ medusa.” The 
development of the air-sac is analogous ; that of the protecting scales, 
however, is different, without invagination, &c. That the gonophores 
are never placed directly on the stem, always on the so-termed ten- 
tacles [blastostyles], is also a rather important observation. 
Physophora borealis^ Sars, Fauna littor. Norv. iii., is identical with 
P. hydrostaticttf of the Mediterranean ; under A galmopsis elegans, Sars 
(op. cit. i.), two forms are confounded : Halistemma elegans^ Sars, and 
Agalmopsis sarsi, K611. (Claus, 1. c.), 
Hydrocokallia. 
Moseley’s brilliant discoveries in the natural history of the Stylas- 
teridce are now published in an elaborate monograph (19) discussing the 
anatomy of the species examined in every histological detail, and giving 
a full account of the generic characters. As these cannot be given here 
fully, the author’s “ tabular synopsis ” is reproduced, with addition of the 
genera added in the postscript and indication of the number of known 
species, of the new ones here (or elsewhere) now first described, and the 
fossil species referred to each genus. 
Hydbocorallin^ ; Hydroids forming a corallum with two kinds of 
zooids, gastrozooids (with mouth) and dactylozooids (without mouth). 
(A.) Milleporidje : Dactylozooids, with numerous tentacles ; ampullae 
absent (reproduction unknown). 
1. Millepora. 
(B.) Stylasterid^ : Dactylozooids devoid of tentacles and tentacle- 
shaped j gonangia contained ‘*in ampullae.” 
(a.) Pores sporadic, not in cyclo-systems ; gastropores [pores 
of gastrozooids] with styles Icolumelloi'] ; dactylopores 
[pores of dactylozooids] without them. 
(a.) Dactylopores of one kind only, 
2. Sporadopora, g. n., Moseley (Polypora,M.os.f olim.): Pores of both 
kinds simple ; gastro-zooids with 4 tentacles. S. dichotoma (Mos.) 
(Polypora, olim.), p. 429, pi. xxxiv. figs. 3 & 4, pi. xxxvi., off La 
Plata, 600 fath. 
3. Pliobothrus^ Pourt. : Dactylopores at the tips of tubular projec- 
tions ; gastrozooids without tentacles. Two species known. P. 
symmeiricus, Pourt., p. 440, pi. xli. figs. 2 & 3. 
4. Errinay Gr. : Gastropores sometimes covered with a projecting 
scale ; dactylopores within nariform projections ; gastrozooids 
with 4 tentacles. Seven species known, including the Lepidoporca 
of Pourtales. E. labiata^ sp. n., Moseley, p. 443, pi. xxxiv. fig. 6 
pi. xxxvii. With Sporadopora dichotoma, &c. 
5. Distichoporay Lmck. : Pores simple, in a triple linear row at the 
lateral edges of the branches of the flabellum, rarely on its faces, 
gastrozooids with 4 tentacles. Nine living species and one fossil 
