190 Prof. Agassiz on the Echinodermata. 



into the Ophiurce proper, and Euryales ; 3rd, the Cirrhigrada 

 or AsteriadcB, which he subdivides into the Urasterice, Solas- 

 terice, Goniasterm, and Asteria proper ; 4th, the Cirrhi-Spi- 

 nigrada or Echinidce, for Avhich he adopts the subdivisions 

 proposed in my ' Prodromus;' 5th, the Cirrld-Vermigrada or 

 Holothuriad(B, of which he makes four famihes, the PsoUdce, 

 the Pentactce, the Thyones, and the Synaj)t(e ; 6th, the Ver- 

 migrada or SipuncuUdce, which he subdivides into three fa- 

 mihes, the SipunculacecE, the Priapidacecs and TJialassamacea. 

 He also places in orders of equal rank, the Crinoidea, the 

 OphiuridcE and the Asteriadce, which in my ^ Prodrome d'une 

 histoire naturelle des Echinodermes ' I had left in a single 

 order ; and he reunites to the Echinodermata the Sipuncididce, 

 which I had withdrawn to place them with the Annelides. I 

 am indeed convinced, after seeing the preparations shown me 

 by Mr. Forbes and Mr. Goodsii*, that the SipuyicuUdce are 

 undoubtedly Echinodermata. The descriptions given by Mr. 

 Forbes of the British species are far more complete than the 

 descriptions previously in my possession ; he has also consi- 

 derably augmented their number, especially in the Holothu- 

 riad(B and SipimcuUda. Conjointly with his friend Mr. Good- 

 sir, Mr. Forbes has established the two new genera Psolinus 

 and Ocnus, and has circumscribed in a most rigorous manner 

 my genera Uraster and Cribella in the Asteriada. Many of 

 the species described by Mr. Forbes were discovered by Mr. 

 Thompson of Belfast, and Mr. Ball of Dublin. Mr. Forbes 

 had previously published, in the eighth vol. of the ' Wernerian 

 Transactions of Edinburgh,* a memoir upon the Asteriadce of 

 the Irish Sea, in which he had established two new genera 

 [Solaster and Luidia) and described many new species. 



MM. J. Miiller and Troschel have undertaken a revision 

 of the Starfishes [Asteriadce), Avhich they first divide into four- 

 teen and then into sixteen genera, the characters of which are 

 for the most part new and generally circumscribed within just 

 hmits. These genera are as follows : — Asteracanthion, Mid. 

 and Tros. (Stellonia, Nard., Forb., Uraster, Ag.) ; Pisaster, 

 Mill, and Tros. ; Stich aster, Mill, and Tros. ; Echinaster, 

 Mlil. and Tros. ; Crossaster, Mul. and Tros. (Solaster, Forbes); 

 Chcctaster, Miil. and Tros. ; Ophidiaster, Ag. ; Linckia, Nard. 

 (Mill, and Tros.) ; Goniaster, Ag. ; Platyaster, De Blain. (Scu- 

 tastcrias, De Bl.) ; Asterope, Miil. and Tros. ; Cuicita, Ag. ; 

 Asteriscus, Miil. and Tros. (Asterina, Nard., Pahnipes, Linck) ; 

 Ar chaster, Miil. and Tros.; Asterias, Ag. (Astropecten, Linck, 

 Stellaria, Nard.) ; Hemicnemis, Miil. andTros. (Luidia, Forbes). 

 The researches of these gentlemen, as yet only made known 

 by extracts which have appeared in the Bulletins of the Aca- 



