12 ECHINOIDEA. I. 



writer upon the classification of the Echinoidea since Desor has complained of tlie misatisfactory 

 atterapts 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 vahie, 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 fossilen Cidariden in Gattungen und Untergattungen ist bisher eine ungeloste Auf- 

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

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

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

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



Agassiz in his <- Revision of Echini keeps the genera: Cidaris, Dorocidarts, Phyllacantkus, 

 Steplianocidaris, Porocidaris, and Goniocidaris\ Dorocidaris and Phyllacaiifhus, however, are more nearly 

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

 Echinoids (8 p. 33). They are here f urther defined in the following way: i Dorocidaris would include 

 all forms with narrow ambulacral areas and long slender, serrated spines, while Phyllacautlius 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 . W)' vi Ile Tliomson (395 p. 772) among the recent Echinoids onl_\- 

 acknowledges the genera Cidaris, Porocidaris, and «possibly Goniocidaris. Pomel (324) divides the 

 Cidarids into three subfamilies, viz. /rj Cidarieiis with the genus Eucidaris (with trois espéces vivantes , 

 none of which are mentioned) as the only recent representative ; les Goniocidarieiis with the recent 

 genera Goniocidaris and Dorocidaris; and les Rhabdocidariens with the genera Phyllacanthits (with the 

 subgeniis Stephanocidaris\ Leiocidaris and Porocidaris. The genus Schleiniizia Studer is supposed to 

 be a Rhahdocidaris, consequently also to belong to this subfamily. Duncan (132) onh' admits the 

 genus Cidaris with the subgenus Goniocidaris; the other earlier genera are onh- classed as <:div-isions -. 

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

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

 Cidaris, n'out jDas été heureuses; on trouvera toujours tant de passages entre les espéces, en apparence 

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

 qui apparait des la fin de Tére paléozoique et traverse des lors tons les etages, sans manquer dans 

 aucune, pour se retrouver enfin dans les mers actuelles sans avoir modifié aixcun de ses caractéres*. 

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

 iu his above quoted, large and excellent work o 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, Stereocidaris (known until then only as fossil 

 from the cretaceous period), Eucidaris, Leiocidaris, Porocidaris, and Goniocidaris. 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 nobod}- is able to recognise them 

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



