MUSEUM OF COMPARATIVE ZOOLOGY. 279 



Lamarck, and limit them to genera, as we understand them now, have 

 been most confusing. Not that I would ignore writers who, like Brey- 

 nius, Leske, Klein, Linck, were often far in advance of many modern 

 publications, but when the so-called restoration amounts to sweeping 

 out of existence genera which are well understood, and properly de- 

 fined, and have been current in literature for more than half a century, 

 and replacing them by generic names of doubtful limitation, I can consider 

 such radical changes as anything but progress and justice. It seems to me 

 that unless these changes are made • ich as much discretion and judgment 

 as they have been made by Desor in his Synopsis, applying the old name 

 to a subdivision, and retaining at the same time the current name for a 

 portion of the genus thus subdivided, they are not calculated to advance 

 our knowledge of Echinoderms. For instance, the attempt to substitute 

 Echinanthus (which includes genera as widely different as Echinolam- 

 pas, Conoclypus and Clypeaster) for Clypeaster, while D'Orbigny consid- 

 ered Echinolampas as identical with Echinanthus; the adoption of 

 either view involves endless confusion, and Dasor's solution is so natural 

 that we must, as a general rule, take his definitions, in spite of the 

 priority of this and many other restorations proposed by Gray, which are 

 liable to similar objections- 

 Littoral, to 80 fathoms. 



II. On the Young Stages of Echini. 



From the large number of small-sized Echini collected by Mr. 

 Pourtales it became necessary, in order to study them intelligently, to 

 examine the young of as many species as possible, and obtain some 

 criterion by which to determine this collection accurately. As the results 

 to which this examination has led me form the basis of the preceding 

 descriptions, it is not out of place to give the proofs, as far as they can 

 be given by a short resume and without figures, of the conclusions to 

 which I have been led by the study of these young, leaving for a more 

 elaborate paper a detailed description, as well as figures, of the changes 

 here mentioned, which these young undergo. Some of the specimens 

 collected by Mr. Pourtales are so small that they must have absorbed 

 their Pluteus very recently before their capture. This collection, taken 

 in connection with the Museum materials, gave the means of studying 

 the changes due to growth of the following species : — 



Cidaris annulata Gray. 



Dorocidaris abyssicola A. Ag. 



