CEPHALOPODA. 



73 



Ovate, small, with an oblong-ovate aperture. Fossil at 

 Grignon. 



FAMILY V. CRISTACEA. 



Shell semidiscoid, with an eccentric spire. 



Genus23.— ORBICV LIN A.— Lamar cL 



Generic Character. — Shell subdiscoid, multilocular; spire 

 eccentric ; volutions contiguous and compound ; chambers 

 short and very numerous ; septa imperforate. 



Orbiculina uncinata. — The Uncinate Orbiculina. 

 Plate X. fig. 19. Spirally striated, and the volutions sepa- 

 rated by a deep sinus. Fossil. 



GeJiMS 24.— CRISTELLARIA Lamarck. 



Generic Character. — Shell semi-discoidal, multilocular; 

 volutions contiguous and simple, progressively enlarging; 

 spire eccentric, sublateral ; septa iinperforate. 



Cristellaria squammula. — The Scaled Cristellaria. 

 Plate X. fig. 20. Shell externally covered with minute 

 scale-like marks. Fossil. 



Genus 25.— RENULIN A.— ZamorcA. 



Generic Character. — Shell kidney-shaped, flat, sulcated, 

 and multilocular ; volutions linear, contiguous, curved 

 around a marginal axis, those most remote from it being 

 longest. 



RenuUtes opercularis. — The Lid-shaped Renulina. 

 Plate X. fig. 21. Semilunar, flat, with arcuated concentric 

 ridges. Fossil at Grignon. 



FAMILY VI. LITUOLACEA. 



Shell somewhat spiral ; the last volution continuous in a 

 straifrht line. 



