287 



NOTES 



On Foreign Jurassic species of the genus PYGASTER nearly allied to 

 British forms, but which have not yet been found in the English Oolites. 



Pygaster laganoides, Agassiz. Ecbmoderm. Foss. Suisse^ tabl. 12, figs. 13 — 16, 



Desor. Monogr. des Galerites, tabl. 11, figs, 5 — 7, 



Test sub-circular, depressed ; four rows of tubercles in the ambulacra, which are one 

 third the width of the inter-ambulacra ; twelve rows of tubercles in the inter-ambulacra ; 

 the tubercles are large, and nearly all of the same size ; base concave, mouth opening large, 

 peristome feebly notched ; anal opening large, of an elongated form, and occupying nearly 

 two thirds of the single inter-ambulacrum. 



Dimensions. — Height, six tenths of an inch ; transverse diameter, one inch and six 

 tenths ; antero-posterior diameter, one inch and a half. 



Formation. — Bathonien, " Calcaire a polypiers de Ranville," Normandy. 



Collections. — Deslongchamps, Michelin, d'Orbigny ; my cabinet. 



Pygaster Gresslyi, Desor. Monogr. des Galerites, p. 80. Synopsis des Echinides 



Foss., tabl. 22, figs. 1, 2. 

 Cotteau. Etudes sur les Echinides Foss., pi. 28, figs. 2 — 6. 



Test thin, small, sub-pentagonal, depressed ; inflated at the sides, flat at the base , 

 ambulacra with four rows, inter-ambulacra with twelve rows of tubercles at the 

 circumference; the tubercles are large, equal-sized, and surrounded by granules; anal 

 opening pyriform, contracted near the disc; base concave, mouth opening moderate in 

 size, peristome deeply notched ; tubercles at the base surrounded by hexagonal areolas. 



