EXPLANATION OF PLATES 

 Plate i 



Page 



Galeropygus agaricifonnis (Wright) 24 



I, Adapical view ;s«2, adoral view ; 3, rear view ; 4, ambulacrum V. 



Jurassic (Inferior Oolite), Cheltenham, England, U.S.N.M. 19561. 



Figures 1-3, X I; figure 4, X 3- 

 Ilyboclypiis caudatus Wright 28 



5, Adapical view of specimen in Lambert Collection, Sorbonne, Paris, 

 from Jurassic at Cheville (Sarthe), France, X li- 



Flyboclyptis gibberulus Agassiz 27 



6, 7, Adapical view, adoral view of specimen in Lambert Collection, 

 Sorbonne, Paris, from Jurassic (Eathonian) at Amberieux (Ain), 

 France, X i 



Plate 2 



Pygunis (Pygunts) monimolUni (Agassiz) 45 



1, Adapical view of specimen in ficole National Superieure des Mines, 

 Paris, from Lower Cretaceous (Neocomian), St. Sauvre, France, X s- 



Py gurus {Mepy gurus') depressus Agassiz 48 



2, 3, 5, Adapical, right side, adoral view, of specimen from Jurassic 

 (Callovian) of Poin, France, in ficole National Superieure des Mines, 

 Paris, X f . 



4, Floscelle of specimen from Jurassic (Callovian) at Montbizot, 

 Sarthe, France, in the Museum of Comparative Zoology, Harvard, X li- 



Plate 3 



Py gurus {Py gurus) lampas (De la Beche) 46 



1, 3, Adapical and right side of lectotype from Greensand near Lyme, 

 England, in ficole National Superieure des Mines, Paris, X I- 



2, Adoral view of specimen in ficole National Superieure des Mines, 

 Paris, from Cretaceous (Cenomanian) at LeMans, France. 



Pygurus (Pygurus) blumenbachi Kock and Dunker 42 



4, Adapical view of Cottcau's (1869, Pal, franc, Jur., pi. 38, fig. 3; 

 pi. 39; pi. 40, fig. i) figured specimen from the Jurassic (Rauracian) 

 at Thury (Yonnc), France, in the Ccolc National Superieure des Mines, 

 Paris. 



Pygurus (Pygurus) rostratus Agassiz 42 



5, View of floscelle of specimen in Museum of Comparative Zoology, 

 Harvard, from Lower Cretaceous (Neocomian) at Ste. Croix, Switzer- 

 land, X li 



241 



