CLARK: THE CIDARIDAE. 167 



Historical summary. 



The first writer to use the name Cidaris for a genus of Echini was 

 Klein (1734), who, however, included all of the regular sea-urchins under 

 that name. Linne (1758) used the same name for a species of Echinus, 

 but Leske (1778) was the first writer subsequent to Klein who recog- 

 nized Cidaris as a genus. Only one of the 28 species which he includes 

 in the genus belongs in the family Cidaridae as understood to-day, and to 

 that one he gave the name papillata. Now it is clear from both text 

 and figures that Leske intended to include under "the name " Cidaris 

 papillata" all those regular Echini with the conspicuous interambulacral 

 tubercles of the Cidaridae. His " species " is therefore a composite group, 

 including not only the now well-known European Dorocidaris papillata, 

 but also Phyllacanthus imperialis and several species of the restricted 

 genus Cidaris, one of which appears to have been tribuloides Lamarck. 

 The next writer to deal with the classification of the Echini was Lamarck 

 ('16), and he clearly indicates and defines the group which we now 

 call the Cidaridae. He called them " Turbans," under his genus Cidarites. 

 So far as the Cidaridae are concerned the name Cidarites is equivalent to 

 Leske's Cidaris p>apillata and is obviously a synonym of Cidaris. It 

 cannot be used, therefore, at the present time for any genus of animals. 

 Lamarck listed eleven species of " Turbans," all but one of which were 

 recognized and described by Alexander Agassiz in 1872, in his classic 

 "Bevision of the Echini." No attempt to subdivide the genus Cidaris 

 was made until 1835, when Brandt established the genus Phyllacanthus 

 for a supposedly new species, dubia. He divided Lamarck's Cidarites 

 into two sections, A (including the species not in B and for which he 

 selected and named tribuloides Lam. as the type species) and B, Phylla- 

 canthus, with dubia for the type, and including also imperialis, hystrix, 

 geranioides, and pistillaris. Later investigation made it plain that of 

 these four only imperialis and pistillaris are congeneric with dubia, and 

 the other two were therefore returned to Cidaris. In 1872 A. Agassiz 

 showed, however, that Lamarck's baculosa, verticillata, and annulifera 

 had important features in common with dubia and imperialis and accord- 

 ingly placed them in Phyllacanthus. When Agassiz and Desor ('46) 

 considered the Cidaridae, they neglected Phyllacanthus, but established 

 Goniocidaris with geranioides for the type, and with it associated a " new " 

 species quoyi, which subsequently proved to be synonymous with 

 Lamarck's tubaria. In 1854 Desor suggested as genera of fossil Cida- 

 ridae, Ehabdocidaris, Diplocidaris, Porocidaris, and Leiocidaris, and in 



