NO. 3 CASSIDULOID ECHINOIDS — KIER 12/ 



tion, deep transverse groove ventral to opening; peristome anterior, 

 pentagonal ; bourrelets strongly developed, pointed ; phyllodes very 

 broad, deeply depressed between bourrelets, single pored with two 

 series of pores in each half-ambulacrum: approximately 12 in each 

 outer series, 6 in each inner ; buccal pores present. 



Comparison with other genera. — Stigmatopygiis is quite similar to 

 Hardouinia. In both genera the test is large, highly inflated, with 

 supramarginal periproct, broad, closed equal petals, flat adoral surface 

 with very prominent bourrelets, and broad phyllodes. Both genera 

 occur in the Upper Cretaceous and are certainly closely related. 

 Stignmtopygus is distinguished from Hardouinia by the deep trans- 

 verse groove ventral to its periproct, and by its anterior peristome. 



Apparently these two genera occurred in the same type of environ- 

 ment as is indicated not only by their morphological similarities, but 

 by their occurrence in rocks of strikingly similar Hthology. According 

 to personal communication with M. Collignon, specimens of Stig- 

 matopygns lamberti Besairie occur in Madagascar in great numbers 

 in a very coarse sandstone that is almost devoid of other fossils. 

 Hardouinia mortonis (Michelin) occurs in southeastern United States 

 in rocks of similar Hthology. As discussed in detail on page 22, this 

 echinoid probably lived in a high-energy, littoral environment. 



Range. — Cretaceous (Cenomanian to Senonian) of Africa and 

 Europe. 



Remarks. — I was unable to find any specimens of the type species, 

 S. galeatus, in any of the Paris museums. According to d'Orbigny 

 (1856, p. 333) the holotype, presumably the only specimen known, 

 was in the D'Archiac Collection. According to Lambert and Jeannet 

 (1928, p. 102), the D'Archiac Collection is not intact, as he sold 

 many of his specimens. 



I have been able to study many specimens of Stigmatopygus 

 l-amherti Besairie, a species very similar to 5". galeatus and certainly 

 congeneric with it. I include a description and figures of this species 

 as a substitute for a description of the type species. 



STIGMATOPYGUS LAMBERTI Besairie 

 Plate 20, figures 5-8; text figures no, in 



Stigmatopygus lamberti Besairie, 1930. Bull. Soc. Hist. Nat. Toulouse, vol. 60. 

 p. 572, pi. 13, figs. 1-8. 



Material. — General Collignon very kindly lent me 103 specimens 

 from his personal collection. Two specimens were studied in the 

 Museum National d'Histoire Naturelle, Paris. 



