On the Genera Pseudopygaulus, Trachyaster, (&c. 327 



XLII. — Ohjections to the Genera Pseudopygaulus, Coquand^ 

 Trachyaster, Pomel, and Ditremaster, Munier- Chalmas : 

 their Species restored to Eolampas, JDunc. & Sladen, and 

 Hemiaster, Desor. By Prof. P. Maetin Duncan, F.R.S., 

 and W. Peecy Sladen, F.G.S., Sec. Linn. Soc. 



Contents. 



The History of Eolampas; its precedence of Psettdopygauhis aud 



Petalaster. 

 A OriLicism of the so-called Genus Trachyaster, Pomel. 

 A Criticism of the so-called Genus Ditremaster, Mimier-Chalmas. 

 List of Genera and Species, with Synonyms. 



We regret that we cannot agree to some alterations in the 

 classification of the Ecliinoidea which have lately been made 

 by our much respected friend and fellow- worker in the group, 

 M. Cotteau. 



JVl. Cotteau, without giving us the opportunity of debating 

 the subject, has altered the generic position of some of the 

 species of Echinoidea which we described in the ' Palaeonto- 

 logia Indica,' ser. xiv., Foss. Ech. of W. Sind and of Kach 

 and Kattywar, 1882-85, has placed our names after the 

 species in brackets, has introduced his own without that ob- 

 jectionable enclosure, and has published the alterations in the 

 Pal. FrauQ. £ch. terr. Eocene, 1887. 



I. 



One of the most important of the alterations has been made 

 in consequence of a misinterpretation of the law of priority of 

 description and publication on the part of M. Cotteau, who, in 

 his evident desire to do what he thought correct, has done us 

 a wrong. 



During the study of the Echinoidea of W. Sind we found 

 some very remarkable species, which could not be placed in 

 any genus which had been published up to that date, and the 

 genus Eolampas was founded and published to receive them. 

 A typical species was described and figured, besides others, 

 and the work including them was published in 1882 and 

 circulated widely (Pal. Ind. ser. xiv., Foss. Ech. W. Sind, 

 p. 61). 



In 1884 a genue Petalaster was diagnosed and published 

 by M. Cotteau, with a typical species, in '' Ech. nouv. ou peu 

 connus," Bull. Soc. Zool. France, 1884, fasc. 3, p. 39. In 



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