410 FOREIGN JURASSIC PYGURUS." 



Pygurus (Echinanthus) orbiculatus, Leshe. Syn. IPygums 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 v/hich 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. Fygurus Marmonti, Desor, Synopsis des Echinides 



Possiles (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 which 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 ; 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). 



