243 



sides : ears of the upper or left valve equal in size and similar in shape, 

 ascending obliquely outwards from the beak and truncated also obliquely 

 at the outer margins. Ears of the under or right valve unknown. 



Surface of the upper valve polished and nearly smooth to the naked 

 eye, but when examined with a moderately powerful simple lens it is 

 seen to be marked with exceedingly numerous, minute and very closely 

 disposed concentric stria*, also by very faint and somewhat more distant 

 radiating lines. Test extremely thin. 



Maximum length of the most perfect valve, forty-two millimetres : 

 height of the same, as measured from the beak to the centre of the 

 basal margin, forty-five mm. 



North Shore of Cumshewa Inlet : two or three specimens in a concre- 

 tionary nodule of shale. 



This shell may be a mere variety of the Camptonectes bellistriatus of 

 Meek, (see Palaeontology of the Upper Missouri, page tT) but the 

 upper margins of the ears of its light valve are ascending and not 

 straight. 



OSTREA SKIDEGATENSIS. (Nom. Prov.) 



Plate 32, fig. 1. 

 Ostrea. (Sp. Undt.) This volume, page 83. 



Fi.g 12. Ostrea Skidegatensis. 



Outline of the interior of an upper valve of a 

 separate specimen. 



