NO. 3 CASSIDULOID ECHINOIDS — KIER 45 



fig. 22). In interambulacrum 5 of two specimens, there are one or 

 two plates on the adoral surface inserted between (text fig. 23) the 

 regular plates of the interambulacrum. As the plate sutures are 

 usually not clear in the phyllodes, I have included (text fig, 24) a 

 drawing of a phyllode in which most of the sutures are visible. 



Remarks. — Cooke (1955, p. 98) transferred his Faujasia chclo- 

 nium to Pygurus. Having single-pored phyllodes and a monobasal 

 apical system, this species is not a Pygurus, but is referred below 

 (p. 141) to a new genus. 



Range and distribution. — Middle Jurassic (Bajocian) to Cretaceous 

 (Cenomanian) of worldwide distribution. 



Subgenus PYGURUS Agassiz 



Type species. — Echinolampas montmoUini Agassiz. 



Remarks. — This subgenus includes those species of Pygurus that 

 have a slightly elongate, somewhat inflated test, an anterior apical 

 system, broad, depressed phyllodes with from three to one series of 

 pore pairs in each half -ambulacrum, and with the first pore pairs 

 in a phyllode widely separated from the edge of the peristome. This 

 subgenus is more advanced than Pygurus (Me pygurus). 



Range. — Jurassic (Oxfordian) to Cretaceous (Cenomanian), 



DESCRIPTION OF TYPE SPECIES 



PYGURUS (PYGURUS) MONTMOLLINI (Agassiz) 



Plate 2, figure i ; chart 3, figure h 



Echinolampas montinollini L. Agassiz, 1836a. Mem. Soc. Sci. Nat. Neuchatel, 

 vol, 1, p. 134, pi. 14, figs. 4-6. 



Material. — Five specimens were seen in Paris, two in the Museum 

 National d'Histoire Naturelle, and three in the ficole des Mines. 

 The floscelle and peristome was not visible on any of these specimens. 



Shape. — Large, broad, width slightly greater than length, with 

 greatest width slightly posterior to center ; slight, broad anterior 

 groove, posterior margin slightly pointed, lobcd on either side ; 

 adapical surface inflated with greatest height at apical system ; adoral 

 surface pulvinate with interambulacra swollen, ambulacra depressed, 

 area around periproct flattened. 



Apical system. — Anterior, tetrabasal, genital plates large, extending 

 posteriorly, separating posterior genital plates; posterior oculars in 

 contact. 



Ambulacra. — Petals broad, equal, closed, long, petal III extending 



