FOREIGN JURASSIC PYGURUS. 411 



Collections. — MM. Michelin, Deslongchamps, Cotteau, my cabinet, 



Pygurus Icaunensis, Cotteau. Etudes sur les Echinides Foss., pi. xxxvii, xxxviii. 



Test large, sub-circular, length and breadth nearly equal ; upper surface elevated 

 and conoidal ; under surface concave ; ambulacral areas petaloid, very narrow below, 

 dilated in the middle, and lanceolate above ; poriferous zones wide, and petaloidal two 

 thirds the distance between the disc and border ; base deeply concave ; basal inter- 

 ambulacral areas very convex and prominent; mouth-opening excentral, small, pentagonal, 

 nearer the anterior border, surrounded by five oral lobes, and five wide ambulacral petals ; 

 anal opening large, oval, infra-marginal, situate in a deep depression. This large species 

 resembles F. Hausmanni, of which M. Desor suggests it may probably be a variety ; the 

 plaster mould in my collection exhibits very decided specific differences between it and the 

 discoidal urchin I have identified with the German species. 



Dimensions. — Height, one inch and a quarter ; antero-posterior diameter four 

 inches and a half; transverse diameter, four inches and three 

 tenths. 



Formation. — Calcareo-siliceous strata of the Inferior Coralline Oolite at Druyes, 

 (Yonne). Rare. 



Collections. — M. Cotteau; only two specimens known.' A plaster mould of the 

 figured specimen in my collection. 



Pygurus tenuis, Desor. Synopsis des Echinides Fossiles, p. 315. 



" Test large, circular, much dilated ; border thin, almost trenchant ; summit central ; 

 ambulacral petals very long, petaloidal almost to the margin." Desor. 



Formation. — " Portlandien inferieur (Astartien) d'Oberbuchsitten (Canton de Soleure), 

 Oolite Astartienne de Laufon (Jura Soleurois), Delemont." Desor. 



Collections. — Mus. de Neuchatel; M. MicheUn. 



