Mr. J. E. Gray on Starfish. 175 
and Alcyonidium parasiticum, all more or less rare on the 
English coast, are tolerably abundant in these situations. I 
might enlarge upon this subject, but the data are at present 
too few tv admit of our doing so with certainty. 
Many species appear to attain a much greater height in 
[reland than in England, as will be evident on a comparison 
of the sizes given in Dr. Johnston’s elegant work and in this 
Catalogue: this is probably attributable to the mildness of 
the climate. 
EXPLANATION OF THE PLATES. 
Puate V. Fig. 1. Antennularia ramosa. 
Fig. 2. A portion of the same magnified. 
Fig. 3. A portion of 4. antennina magnified, showing the small tu- 
bular cells placed between the larger ones, and which are absent 
in A. ramosa. 
Pirate VI. Fig. 1. A specimen of Farcimia sinuosa, of the natural size. 
fig. 2. A portion of the same magnified. 
Fig. 3. and 4. Specimens of Tubulipora verrucaria; in the one the 
tubes are separate, in the other united. 
Fig. 5. Lepralia 4-dentata. 
Puate Vil. Fig. 1. Flustra Hibernica. This is a very imperfect represen- 
tation of the original, the exact appearance of which it is very 
difficult to represent in a drawing. 
Fig 2. Melobesia elegans of Mr. Bean, magnified. 
Fig. 3. and 4. Crisia aculeata, a new species. 
XXII.—A Synopsis of the Genera and Species of the Class 
Hypostoma (Asterias, Linneus). By Joan Epwarp Gray, 
Esq., F.R.S., Keeper of the Zoological Collection in the 
British Museum. 
My intention in sending this paper to the press is not only to bring 
before the public a number of new genera and species which have 
been for several years in the collection of the British Museum, but 
also to attempt to divide what has hitherto been considered an in- 
tricate Class into natural groups, to subdivide these groups and the 
genera they contain into smaller sections, so as to facilitate the de- 
termination of the species, and at the same time to assist in making 
out the natural affinities of this much-neglected group of animals. 
Hitherto very few persons have attempted to divide the Starfishes 
(Asterias, Linn.) into natural groups, and it is but recently that 
Nardo, and subsequently M. Agassiz, have paid any attention to the 
good groups pointed out by the first author of anything like a Mono- 
graph of these animals, I mean of Henry Linck, who published a se- 
parate work on the subject in folio, which he dedicated to Sir Hans 
Sloane and the members of the Royal Society. Nardo has done 
little more, as I shall presently show, than. rename Linck’s divisions ; 
and M. Agassiz has followed in Nardo’s footsteps, adding one or 
