KKV-TABLE. 



115 



Chalk (Cknomanian-Sexoniax) Si-ecies. 

 r. — Marginals four-sided, with sides rectilinear or almost rectilinear; broad. 



A. Without a rabl)et-edge. CallUlenna, Nijmphastcr, I'eiitagonaster. 



B. With a rabbet-edge. Metopaster, MUrasfry. 

 c. With a distinct ridge. Artkraster. 



II. — Marginals either hexagonal or rounded; very thick. Iladranderaster. 

 III. — Marginals wedge-shaped, high, spine-pits very shallow or absent. Pijcinaster. 

 IV. — Marginals breast-plate-shaped. Staiiramle raster. 



Y .—Miscellaneous plates. 



I. — ^Marginals fom'-sided, with sides rectilinear or almost rectilinear. Pedi- 

 cellarise when present of a simple bi-valvate character. 



A. Without a rabbet-edge. Calliderma, Nymphaster, I'entdyonaster. 



1. Spine-pits shallow, hexagonal, giving a honeycomb appearance. 



(A) 



(B) 



■^ 



Text-fio. 8. 



a. Honeycomb medium ortiiio. C.Smithiie (see p. 123). 

 Text-fig. 8 a. — Variety with iiieilium-sized spiue-pits 



(see p. 123). 

 Text-tig. 8 B. — Variety with iiae spiue-])its (see 



p. 123). 



b. Honeycomb coarse. N. Cooiiibli. Text-fig. 3, p. 113. 



c. Honeycomb confined tt) a portion of the plate (or 

 absent). P. iibtiisuK. Text-tig. 9. 



T«xT-rio. 9. 



