190 



Prof. Agassiz on the Echinodermata. 



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

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

 terice, Goniasterice, and Asterice proper ; 4th, the Cirrhi-Spi- 

 niyrada or Echinidce, for which he adopts the subdivisions 

 proposed in my 6 Prodromus;' 5th, the Cirri ti-Vermiyrada ox 

 Holothuriadce, of which he makes four families, the Psolidce, 

 the Pentactce, the Thyones, and the Synaptce ; f>th, the Ver- 

 migrada or Sipunculidce, which he subdivides into three fa- 

 milies, the Sipunculacece, the Priapulacece and Tlialassamacece. 

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

 Ophiuridce and the Asteriadce, which in my £ Prodrome d'une 

 histoire naturelle des Echinodermes 5 1 had left in a single 

 order ; and he reunites to the Echinodermata the Sipunculidce, 

 which I had withdrawn to place them with the Annelides.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. Goodsir, that the Sipunculidce 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- 

 riadce and Sipunculidce. 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 Asteriadce. 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 c 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), which 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 

 limits. These genera are as follows : — Asteracanthion, MU1. 

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

 Miil. and Tros. ; Stichasier, Mul. and Tros. ; Echinaster, 

 Mid. and Tros. ; Ci'ossaster, Mul. and Tros. (Solaster, Forbes) ; 

 Chcetaster, Mill, and Tros. ; Ophidiaster, Ag. ; Linckia, Nard. 

 (Mul. and Tros.) ; Goniaster, Ag. ; Platy aster, De Blain. (Scu- 

 tasterias, De Bl.) ; Asterope, Mul. and Tros. ; Culcita, Ag. ; 

 Asteriscus, Mill, and Tros. (Asterina, Nard., Palmipes, Linck) ; 

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

 Stellaria, Nard.) ; Hemicnemis, Mul. andTroSc (Luidia, Forbes). 

 The researches of these gentlemen, as yet only made known 

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



