176 Mr. J. E. Gray's Synopsis of 



two fossil genera which did not come within Linck's or Nardo's ob- 

 ject. Mr. Edward Forbes has lately published a description of some 

 Manx species, in which he has divided the Stellonia of Nardo into 

 two genera, and added a genus which he calls Luidia for a species not 

 known to Linck : he has also used the number of series of suckers 

 (a character noticed by M tiller and others) as a generic one. 



Linck divides the Starfishes {Asterias, Linn.) into two great groups 

 by the presence or absence of the ambulacra on the lower side of the 

 arms, calling the first, which exactly agrees with the Asterias of 

 Lamarck, the Asteriadm of this paper, " stellis fissis," and the 

 second " stellis integris." The latter group he divides into three 

 classes : viz. 



1. Stellis vermiformibus = the Ophiura of Lamarck. 



2. Stellis crinitis ? = the Comatula of the same author. 



3. Astrophyton, which is the Euryale of the same. Thus we 

 see, that he distinguished all the natural groups, which were after- 

 wards thrown together into a single genus to be artificially divided 

 into sections by Linnaeus and his followers. Linck's groups were not 

 again recognized until nearly half a century after the publication 

 of his valuable work. 



In dividing the fissured Starfishes, or Asteriadce as we call them in 

 modern nomenclature, into genera, Linck began badly by paying too 

 much attention to the number of the rays, though it is evident, by 

 the names he has given to the different species in his genera, that he 

 was aware that some which he separated on this account were very 

 nearly allied to each other. Overlooking the genera which are formed 

 solely on this character, such as Trisactis, Tetractis, Hexactis and He- 

 ptactis, which are all formed on varieties or distortions of other spe- 

 cies, we shall find that the others noticed by him are excellent ge- 

 nera, and such as are now acknowledged. His 



1. Pentanogaster = Goniaster (*) Agassiz. Scutasteries, Blainv. 



2. Pentaceros = Goniaster (**) Agassiz. Asterina, Nardo. Pla- 

 tasteries, Blainv. 



3. Astropecten = Stellaria, Nardo. Asterias, Agassiz. 



4. Palmipes = Anseropoda, Nardo. Palmasteries, Blainv. 



5. Stella coriacea = Stellonia, Forbes. Stellonia, part, Nardo. 

 Pentasteries and Solasteries, Blainv. 



6. Pentadactylosaster = Cribella, Agassiz not Edwards. Linckia, 

 Nardo not Agassiz. 



7. Octactis, "1 



n * t^ .. ' I = Solaster, Forbes. Stellonia, part, Nardo 

 9. Decactis, > , . ' L 



10. Dodecactis, f ™d ^«*«. 



11. Triskaidecactis, J 



Nardo, in the Naturforscher for 1833, and in the Isis for 1834, p. 

 716, gives the following arrangement of the European species, whicli 

 he divides into five genera : — 



1. Stellaria= Astropecten, Linck. 



2. Stellonia = Stella coriacea, Linck, and his other genera above 

 enumerated. 



