PREFACE. IX 



use than I have done of the valuable papers on the Echi- 

 nidee by M. Desmoulins, but could lay hands on a portion 

 of them only. Since I commenced the publication two 

 papers have appeared which I must notice, as they add 

 several to my enumeration of the synonyms of the Star- 

 fishes. The one is a Memoir by one of the greatest living- 

 physiologists, Muller of Berlin, on the genera of the Star- 

 fishes, read before the Berlin Academy in April 1840. 

 This paper must be praised on account of the excellent 

 way in which the characters of the genera are drawn up. 

 The chief novelty is the employment of the anus of Star- 

 fishes (or anal pore) as a source of family distinction, which 

 aperture Muller describes as existing in all Starfishes saving 

 Asterias proper, and a new genus, Hemichemis, which 

 seems identical with my previously constituted Luidia. 

 His genus Crossaster, also, is my Solaster, published the 

 year before. Several generic names previously adopted 

 by Agassiz and Nardo are wantonly changed ; thus, Uras- 

 ter is turned into Asterocanthium, and Palmipes into As- 

 teriscus, with which he unites Asterina. In this paper 

 Muller maintains that one of the five intermediate inferior 

 plates of the Ophiuridse bears a madreporiform tubercle, 

 or rather corresponds to that body, a view which I am not 

 inclined to adopt. 



The other Memoir to which I must allude is one by Mr. 

 Gray on the Starfishes, which he calls the class Hypostoma, 

 and defines somewhat ambiguously, published simultane- 

 ously with my two first numbers, in the Annals of Natural 

 History. I am afraid I must censure Mr. Gray for chang- 



