596 Mr. H. L. Clark o)i the 



divides it into four varieties or forms. Fortunately the 

 references to figures under these forms are sufficiently con- 

 sistent, so that it is easy to determine to what species each 

 form is to be referred, Leske recognized thisfact^ and gave 

 each form a new name. lie first selected the third one, and 

 called it Echinodiscus quinquiesjierforatus ; next he removed 

 the fourth form as Echinodiscus orbicularis ; next comes the 

 second, which he called Echinodiscus deciesdigitatus. The 

 name orbicidus is thus left for the first form alone, and 

 Leske^s name deniatus, which he gave last of the four, must 

 be regarded as a synonym. As Agassiz in 1841 placed this 

 species (under a pre-Linnean name) in his genus Rotula, 

 where it has since remained, it becomes the type of that 

 genus by virtual tautonomy, if for no other reason. 



The first post-Linnean writer whose work affects clype- 

 astroid nomenclature is Leske, 1778. The idea of dating 

 Echinocyamus and Echinoneus from Van Phelsum, 1774, 

 seems to me absurd. It is true that he uses both names, 

 but he is not a binomial writer, his diagnoses are inadequate, 

 and he gives no species under either '' genus.^^ Even if we 

 wished to, we could not use generic names which are neither 

 adequately diagnosed nor assigned any constituent species. 

 The question whether we accept these names of Van Phelsum 

 or not is unimportant, however, for our nomenclature will 

 not be affected, but only the date and author of the two 

 names *. It may be added that if we are to date these 

 names from Van Phelsum, then Agassiz's name Heliophora, 

 proposed in 1840, has precedence over the universally used 

 name Rotula, Agassiz, 1841. Heliophora has been rejected, 

 and rightfully it seems to me, because it has no constituent 

 species, and therefore cannot be assigned a type ; and this is 

 the status of Echinocyamus and Echinoneiis of Y an Phelsum. 

 For my part I do not see how, under the Code, such genera 

 can be maintained. Under Article 30 we read — " In no case 

 . . . can a species be selected as type which was not originally 

 included in the genus " ; and I do not see how one can 

 determine what species are included in a genus, where no 

 species at all are mentioned, unless, indeed, the diagnosis is 

 exceptionally exact. 



Leske (1778, Add. ad Klein) groups his clypeastroid 



* Mortensea's argument (1907, ' lugolf ' Ech. pt. 2, p. 38) seems tome 

 sufficient to dispose of Lambert's most unwelcome attempt to upset the 

 hitherto universally accepted usage of the names Echinocyamus and 

 Fibularia. But personally I cannot consider Van Phelsum entitled to 

 consideration in this matter. 



