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 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. Antennularia 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 simtosa, 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 \-dentata. 

 Plate VII. Fig. 1. Flustra Hibernica. This is a very imperfect i*epresen- 



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, Linnaeus) . 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 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 



