48 Mr. F. A. Bather on Eocidaris and 



Down to this point it is perfectly plain that Eocidaris was 

 universally regarded as a Palechinoid or Tessellate, with 

 hexagonal interambulacrals of Lepidocidaroid type, differing 

 from those of Echinocrinus (or Archoeocidaris) in the absence 

 of a basal terrace. It had further been pointed out by Qaen- 

 stedt that Cidaris keyserlingi and C. verneuiliana, not to 

 mention C. coceva, could not be placed in Eocidaris because 

 they were Cidaridpe and not Palecliinoids. The two species 

 C rossica and C. munsteriana, in addition to having been 

 doubtful from the beginning, were now generally referred to 

 Echinocrinus. There remained then available for the type 

 of Eocidaris only the two Devonian species C. Icevispina and 

 C. scrohiculata. The various American species, notably 

 E. drydenensis^ though often utilised for the interpi-etatioii 

 of the genus, never had any claim to be regarded as geno- 

 syntypes. 



This clear and, from tlie nomenclatoral standpoint, 

 satisfactory state of affairs was all of a sudden complicated 

 by the irruption of an enthusiastic student of recent sea- 

 urchins. In giving a summary of various Cidaridae with 

 flexible test, L. Doederlein (1887, p. 39) correctly turned his 

 attention to Cidaris keyserlingi Geinitz, and, being desirous 

 of keeping this in a genus distinct from the recent Cidaris^ 

 he retained for it the name Eocidaris given to it by Desor 

 and accepted by Geinitz at a time when its true structure 

 was not realised. Dr. Doederlein himself gave a more 

 detailed and more correct description of an interambulacrum 

 of the species from the Zechstein of Possneck, and, in con- 

 sequence of the facts thus elicited by him, he drew up the 

 following diagnosis of Eocidaris: — " PaljBozoische Cidariden 

 von geringer Grosse, mit schneidendem ambulacralen Rand 

 desI[nter]A[mbulacral] F[eld]. Coronal|)latten in geringer 

 Auzahl ; Hauptwarzen klein, gekerbt ; Warzenhofe ellipt- 

 isch, etwas vertieft, zusammenfiiessend ; Scrobicularring 

 nicht auffallend. Arten : Keyserlingi aus dem Zechstein 

 u. a." Note the plural, ** und andere." 



Into the details of Doederlein's account, more than con- 

 firmed in the contemporary description by Kolesch (June 

 1887), we need not enter for the present. Sufficient to note 

 that both these accurate observers followed Quenstedt in 

 maintaining the truly Cidarid nature of the species before 

 them. The questions that now concern us are : first, did 

 Doederlein intend to fix on C. keyserlingi as the genotype ? 

 Secondly, had he the right so to do ? Both these questions 

 I answer in the negative. As for the first, there is no 

 reason to suppose any such thing, since Doederlein fixed on 



