NO. 3 CASSIDULOID ECHINOIDS — KIER 225 



is the only figure known of this species. I was unable to find any 

 specimens of this species in the Paris museums and suspect that 

 there are none. From Ebray's brief description of the genus, it 

 appears to be similar to Hyhoclypus except for its apical system which 

 differs from Hyhoclypus in having smaller oculars II and IV. This 

 character alone does not seem to warrant generic distinction for 

 Centropygus, but until more is known of the type species it seems 

 advisable to refer this genus to incertae sedis. 



In his original description of the genus, Ebray spells it both 

 "Centropygus" and "Centroclypus." The first subsequent author to 

 discuss these differences in spelling was Lambert (1935, p. 530), and 

 as first reviser, his decision to use "Centropygus" should be followed. 



Genus CLAVIASTER d'Orbigny 



Clavxaster d'Orbigny, 1856, Pal, Franc, Cretace, ser. i, vol. 6, p. 281. Type 

 species by original designation, Archiacia cornuta Agassiz. 



Remarks. — Four species have been referred to this genus, and in 

 none of the specimens of any of these species is the adoral surface 

 preserved. Nothing is known therefore about the peristome, floscelle, 

 if present, or peripoct. It is not possible to know the affinities of 

 this genus, or whether it is even a cassiduloid. Most authors have 

 considered Claviaster a close relative of Archiacia. Both genera have 

 a highly inflated test and a nonpetaloid ambulacrum III. However, 

 these two similarities do not seem to be sufficient evidence for con- 

 sidering these genera as close relatives. The petals in Claviaster are 

 very different from those of Archiacia. There is no way of predicting 

 the character of the adoral surface of Claviaster, and it may have 

 been entirely different from that of Archiacia. For this reason 

 Claviaster is not placed with Archiacia, but in incertae sedis. 



I have included photographs of the holotype of both C. cornutus 

 (pi. 23, fig. i) and C. lihycus Gauthier (pi. 23, fig. 2). Both of these 

 specimens are in the Museum National d'Histoire Naturelle, Paris. 



Pomel's (1883, p. 55) Passalasfer is probably a synonym of 

 Claviaster. He based the genus on his species Claviaster costatus, 

 this species in turn being based on a specimen that Cotteau had 

 referred to C. cornutus. Because Cotteau had said that all the 

 ambulacra were similar, whereas ambulacrum III is different from 

 the others in C. cornutus, Pomel made a new species for the speci- 

 men, and a new genus for the species. However, Lambert and 

 Thiery (1921, p. 359) state that Cotteau was mistaken and that 



