Prof. Agasslz on the Echinodermata. 191 



demy of Berlin for April 1840, and in Wiegmann's ' Archives' 

 for the same year (pp. 318 and 367), contain valuable details 

 upon the organization of these animals. More recently MM. 

 Miiller and Troschel have extended their investigation to the 

 Ophmriddi, and have published a highly interesting sketch of 

 the genera in this family, whose number they contend is not 

 less than eight, without including the genera which 1 have 

 established in the fossil species. These genera are Ophiolepis, 

 Miil. and Tros. ; Opliiopliolis, Miil. and Tros. ; Ophiocoma, 

 Ag. ; OphiothrLv, Miil. and Tros. ; Ophioderma, Miil. and Tros. 

 (Ophiura, Lam.) ; Ophionyx, Miil. and Tros. ; Ophiomyxa, 

 Miil. and Tros. ; and Ophiocnemis, Mid. and Tros. (Wieg. 

 Archiv, 1840, pp. 326-368). 



Mr. J. E. Gray has published an extended and very im- 

 portant memoir on the Asteria in the ' Annals and Magazine 

 of Natural History'for Nov. and Dec. 1840. The tendency 

 of this memoir differs altogether from that published by 

 MM. Miiller and Troschel ; for whilst the Berlin naturalists 

 had especially in view the study of the organization of the 

 Asterice in detail, Mr. Gray had for his object the grouping in 

 the most natural manner the entire assemblage of species 

 which he had had occasion to examine, and which are very 

 numerous, particularly in the section of the Pentacerotidce. 

 Mr. Gray establishes among the true Asterioi alone, forty-five 

 genera (besides numerous subgenera), which he divides into 

 the four following families : — 



AsTERiAD^, Gray : Asterias, Gray (Pentasterias, De Bl., Stello- 

 nia, Nardo, Forbes, Uraster, Ag., Asteracanthion, Miil. and Tros.) ; 

 Heliaster, Gray (Solasterias, De Bl.) ; Tonia, Gray (Stichaster, Miil. 

 and Tros.). 



AsTROPECTiNiD^, Gray : Nauricia, Gray (Archaster, Miil. and 

 Tros.) ; Astropecten, Linck (Asterias, L., Ag., Crenaster, Linck, Stel- 

 laria, Nardo) ; with the subgenus Astropus, Gray, Luidia, Forbes 

 (Hemicnemis, Miil. and Tros.) ; Petalaster, Gray ; So/aster, Forbes 

 (Crossaster, Miil. and Tros.) ; with the snhgenera. Endeca, (iray, and 

 Polyaster, Gray ; Henricia, Gray (Linckia, Forbes, Cribella, Ag., 

 Forbes). 



Pentacerotid^, Gray. 1st, Pentacerotina : Culcita, Ag. ; Penta- 

 ceros, Linck, Gray (Goniaster, Ag.), with the subgenera Nidorellia, 

 Gray ; SteUaster, Gray ; Comptonia, Gray ; Gymnasteria, Gray (As- 

 terope, Miil. and Tros.) ; Paulia, Gray; Randasia, Gray; Anthenea, 

 Gray ; Hosea, Gray ; Hippnsteria, Gray ; Calliaster, Gray ; Go- 

 niaster, Ag. (Gray) ; PenUtgonaster, Gray ; Tosia, Gray. 2nd, Echi- 

 nasterina : Echinuster, Gray (now Miil. and Tros.). 3rd, Crihellina : 

 Othiliu, Gray (Echinaster, Miil. and Tros.) ; Metrodira, Gray (Chaj- 

 taster, Miil. and Tros.) ; Rhop'ui, Gray (Echinaster, Miil. and Tros.) ; 

 Ferdina, Gray ; Dactylosaster, Gray (Ophidastcr, Agass.) ; Tamuria, 

 Gray ; Cistina, Gray ; Ophidiaster, Ag., with the subgenera Hacelia 



