I2 ECHINOIDEA. I. 



writer upon the classification of the Echinoidea since Desor has complained of the unsatisfactory 

 attempts of some of the most distinguished authorities to subdivide the genus Cidaris . . . The divisions 

 were made upon very unimportant external characters, and subsequent research has proved that these 

 structures, the variations of which led them to be considered of good diagnostic value, are of no 

 physiological importance (Duncan (132 p. 29)). In the excellent principal work on the Cidarids, 

 Doderlein's Die japanischen Seeigel (116) he says (p. 35): <Eine wirklich befriedigende Gruppierung 

 der lebenden und fossileu Cidariden in Gattungen und Untergattungeu ist bisher eine ungeloste Auf- 

 gabe gewesen und wird es wohl noch lange bleibeiiv. And then follows, to boot, a remark, anything 

 but encouraging to a systematist, that es ist durchaus nicht zu erwarten , dass die Abgrenzung der 

 Gruppen bei zunehmender Kenntniss eine scharfere werde . Nevertheless I shall here make an 



attempt to solve the problem: the classification of the Cidarids. 



Agassiz in his (Revision of Echini keeps the genera: Cidaris, Dorocidaris, Pliyllacautlnis, 

 Stcphauocidaris, Poroa'daris, and Gouiocidaris; Dorocidaris and Pliyllacautlnis, however, are more nearly 

 regarded as subgenera under Cidaris, what is also especially remarked later, in the Challenger - 

 Echinoids (8 p. 33). Thev are here further defined in the following way: < Dorocidaris would include 

 all forms with narrow ambulacral areas and long slender, serrated spines, while Pliyllacautlnis would 

 include species with broad ambulacral areas, having the poriferous zones joined by a furrow more or 

 less distinct; while Cidaris proper would be restricted to species, in which the pores of the poriferous 

 zone are not so connected . Wyville Thomson (395 p. 772) among the recent Echinoids only 

 acknowledges the genera Cidaris, Poroa'daris, and < possibly Gouiocidaris. Pom el (324) divides the 

 Cidarids into three subfamilies, viz. les Cidaricus with the genus Eucidaris (with trois especes vivantes , 

 none of which are mentioned) as the only recent representative; les Go/iiocidaricns with the recent 

 genera Gouiocidaris and Dorocidaris; and les Rhabdocidaricus with the genera Phyllacantlius (with the 

 subgenus Stcphauocidaris], Lciocidaris and Poroa'daris. The genus Schleiniizia Studer is supposed to 

 be a Rhabdocidaris, consequently also to belong to this subfamily. Duncan (132) only admits the 

 genus Cidaris with the subgenus Gouiocidaris; the other earlier genera are only classed as (divisions . 

 De Loriol (245) comprises a great number of species under the name of Rhabdocidaris Desor; but he 

 owns (p. 7) that «au fond, toutes les tentatives, qui ont ete faites pour demembrer le grand genre 

 Cidaris, n'ont pas ete heureuses; on trouvera toujours tant de passages entre les especes, en appareuce 

 les plus distiuctes, qu'il est douteux pour moi, s'il est vraiment necessaire de diviser ce genre admirable, 

 qui apparait des la fin de l'ere paleozoique et traverse des lors tous les etages, sans manquer dans 

 aucuue, pour se retrouver enfin dans les mers actuelles sans avoir modifie aucun de ses caracteres . 

 The most important contribution to the classification of the Cidarids has been given by Doderlein 

 iu his above quoted, large and excellent work < Die japanischen Seeigel where he attempts to group 

 as well the recent forms as the fossil ones according to their real relation. With regard to the recent 

 forms the following genera are retained: Dorocidaris, Stcrcocidaris (known until then only as fossil 

 from the cretaceous period), Eucidaris, Lciocidaris, Poroa'daris, and Gouiocidaris. But neither is the 

 limitation by Doderlein of these genera satisfactory; above all it holds good with regard to his 

 genera as well as with regard to those of the other authors that nobody is able to recognise them 

 with certainty by the diagnoses given, -- when upon the whole diagnoses are given. After all it is a 



