GLYPHODISCUS. 485 



GENUS 145. GLYPHODISCUS GREV., 1862. 



Valve irregularly circular, 

 generally subquadrangular, with 

 a pseudo-ocellus at each angle 

 centre umbilicate, more or less 

 smooth, umbilicus surrounded 

 by radiating striae, very delicate, 

 terminating in a fine reticulation. 



This genus includes three fossil 



species, all found in the Oamaru 



deposit. The figure in the text 



Fig. 219. 6 lyphodiicus stellatus. represents Glyphodiscus steliatus 



Grez'., which is found in very different localities (Oamaru, Cape of Good Hope, 



Sta. Monica, etc.), and is the type-form of the genus. 



GENUS 146. FENESTRELLA GREV., 1863. 



Valve circular, slightly 

 convex, with a border of 

 small semi-circular hyaline 

 areas, and having two ocelli 

 opposite one another, to- 

 wards the inner third ; strise 

 radiant, except between the 

 two ocelli, where they form 

 straight lines, interrupted 

 at the central portion by a 

 transverse hyaline line. 



This genus was created by 

 Greville for F. Barbadensis 



Fig. 220. Fenestrella Barbadensis. Grev. (fig. 2 2o), a heautiful 



species from the Cambridge Estate, Barbadoes. Professor Brun has added to 

 it two other fossil species from Oamaiu and Yeddo (Japan) respectively. 



