12 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 di\isions 

 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 Gruppieruug 

 der lebeuden und fossilen Cidariden in Gattuugen und Untergattungen ist bisher eine ungeloste Auf- 

 gabe gewesen und wird es wohl uoch lange bleibeu*. And then follows, to boot, a remark, anything 

 but encouraging to a systematist, that tes ist durchaus nicht zu erwarteu, dass die Abgreuzung 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^ Dorocldaris^ Pliyllacaiithus, 

 StcplnDwcidaris^ Porocidaris^ and Goniocidaris; Dorocidaris and Phyllacantlms, howe\'er, are more nearly 

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

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

 all forms with narrow ambulacral areas and long slender, serrated spines, while Pliyllacaiithus 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^ Porocidaris, and possibly Goniocidaris. Pom el (324I divides the 

 Cidarids into three subfamilies, viz. Ics Cidariciis with the genus Eucidaris (with ttrois especes vivantes , 

 none of which are mentioned) as the only recent representative; Ics Goniocidariciis with the recent 

 genera Goniocidaris and Dorocidaris; and Ics Rhabdocidaricns with the genera Phyllacanthus (with the 

 subgenus Stephanocidaris\ Leiocidaris and Porocidaris. The genus Schleinitzia Stnder is supposed to 

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

 genus Cidaris with the subgenus Goniocidaris; the other earlier genera are only classed as < divisions*. 

 De Ivoriol (245) comprises a great number of species under the name oi Pliabdocidaris Desor; but he 

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

 Cidaris, n'ont pas ete heureuses; on trou\era toujours taut de j^assages entre les especes, en appareuce 

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

 qui apjjarait des la fin de I'ere paleozoique et traverse des lors tons les etages, sans manquer dans 

 aucune, pour se retrouver enfiu 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 

 in Iiis 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, Stercocidaris (known until then only as fossil 

 from the cretaceous period), Eucidaris, Leiocidaris, Porocidaris, and Goniocidaris. Ihit neither is the 

 limitation by Doderlein of the.se genera satisfactory; above all it holds good witli 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 tlie whole diagnoses are gi\'en. After all it is a 



