FOREIGN JURASSIC PYGURUS. 409 



NOTES 

 On Foreign Jurassic species of the genus PYGURUS, nearly allied to British 



FORMS, BUT WHICH HAVE NOT YET BEEN FOUND IN THE ENGLISH OoLITES. 



Pygurus acutus, Agassiz. Catalogue raisonne des Echinides, p. 104. 



Test elongated, and depressed, sensibly enlarged before and behind, its form 

 resembling Pygurus productus from the Neocomian, posterior border rostrated, vent 

 oblong, and infra-marginal. 



Formation. — Inferior Oolite of Nantua. 



Collection. — M. d'Orbigny. 



Pygurus depressus, Agassiz. Syn. Pggurus depressus, Cotteau and Triger. Echinides 

 du depart, de la Sarthe, pi. xx, fig. 1 — 6; p. 90. 



Test sub-orbicular, or elongated, slightly depressed before, and much rostrated 

 behind ; upper surface elevated and uniformly convex, inferior surface depressed ; deeply 

 concave in the middle, and having the basal inter-ambulacra much cushioned; discal 

 summit nearly central ; ambulacral areas widely petaloid ; poriferous zones very large, con- 

 tracted at the lower fourth of the dorsal surface, apical disc small, slightly prominent and 

 excentrally forwards ; vent elongated, opening near the posterior border in a deep 

 depression ; mouth-opening, excentral, nearer the anterior border ; peristome penta- 

 gonal, surrounded by five oral lobes, with which five ambulacral petals alternate. 



Dimensions. — Height eight tenths of an inch ; antero-posterior diameter, one inch and 

 four tenths ; transverse diameter, two inches and one quarter. 



Formation. — Kelloway ferrugineux, Ass. No. 2, M. Triger ; Chaufibur, Sarthe. 



Collections. — MM. Triger, Cotteau, one specimen in my cabinet collected by M. 

 Scemann, at Chaufibur, Sarthe, and kindly sent me for this work. 



