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FOREIGN JURASSIC PYGURUS. 



Pygurus (Echinanthus) orbiculatus, Leske. Syn. Pygurus orbiculatus, Cotteau and 

 Triger, Echinides du la depart, de la Sarthe, pi. xix, fig. 6 — 7, p. 88. 



Test large, sub-circular, longer in length than in width ; upper surface a little 

 elevated, sub-conical, and depressed at the border ; base almost flat ; basal inter- 

 ambulacra not prominent ; summit slightly excentrally forwards; ambulacral areas lanceo- 

 late ; poriferous zones very wide, and petaloidal almost to the margin ; apical disc small, 

 slightly excentral ; vent oval, infra-marginal, situated in a deep depression. Mouth 

 opening small, sub-central nearer the anterior border ; peristome pentagonal, surrounded 

 by five small oral lobes, with which five wide ambulacral petals alternate. 



Dimensions. — Height, nine tenths of an inch ; antero-posterior diameter three inches ; 

 transverse diameter, two inches and eight tenths. 



Formation. — Kelloway ferrugineux, Ass., No. 2, M. Triger, Coulans, ChaufFour, Mont- 

 bizot, environs of Mamers, Sarthe. 



Collections. — MM. Michelin, Triger, Gueranger. 



Pygurus Marmonti, Beaudouin. Syn. Pygurus Marmonti, Desor, Synopsis des Echinides 



Fossiles (p. 316). 



Test large, sub-circular, much depressed on the upper surface ; ambulacral areas 

 lanceolate ; poriferous zones wide, petaloidal to the margin ; base flat ; inter-ambulacral 

 basal cushions distinctly flattened on the surface ; mouth-opening small, pentagonal, and 

 sub-central ; peristome surrounded by five oral lobes, which alternate with five ambulacral 

 petals ; vent small, oval, situated in a deep depression removed a short distance from the 

 border. M. Cotteau suggests that it might be necessary to unite this species with P. 

 orbiculatus, from winch it differs in having a more circular form, and likewise in the 

 vent being removed a little farther inwards from the border ; it is found in the same zone 

 with that urchin, and may be only a variety of it. 



Dimensions. — Height, nine tenths of an inch ; antero-posterior diameter three inches 

 and one quarter j transverse diameter, three inches. 



Formation. — " Kellovien de Chatillon sur Seine. Mamers Estrochey (Cote d'Or), 

 Grande Oolite de Normandie." Desor. 



One of the two specimens in my cabinet was collected by M. de 

 Loriere from the " Etage Kellovien ChaufFour, Sarthe." The other 

 ' was obtained from the Kelloway ferrugineux Estrochey (Cote d'Or). 



