Mr. J. E. Gray on Starfish. 1?5 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 to admit of our doing so with certainty. Many species appear to attain a much greater height in Ireland 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. Plate V. Fig. 1. Antennnlaria ramosa. Fig. 2. A portion of the same magnified. Fig. 3. A portion of A. antennina magnified, showing the small tu-bular cells placed between the larger ones, and which are absent in A. ramosa. Plate 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. Plate VJI. 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, IAnnceus). By John Edward 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 any thing 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
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