02 CONTRIBUTIONS 



teeth. It has a distinct fosset, but unlike the genus 

 generally in this, it is placed above the teeth, and directly 

 at the point of the beak. We may, with great propriety, 

 consider this to be the connecting link with the Pectunculi, 

 the "nuance" being into that of the P. ellipsis (nobis). 

 A more complete junction could scarcely be established. 



JV. Brogniarti* Plate 3. Fig. 61. 



Description. Shell elliptically transverse, somewhat in- 

 flated, rounded before, produced and truncate behind, 

 nearly equilateral, furnished with sinuous transverse folds 

 over the disk, and six granose ribs behind, which passing 

 from the beaks to the posterior margin form two channels 

 on each valve ; substance of the shell thick ; lunule lan- 

 ceolate ; escutcheon inflected, lanceolate ; beaks small, 

 pointed, concentrically folded ; anterior series of teeth 

 arched posterior series inflected ; teeth pointed, angular, 

 diminishing in size towards the beak ; fosset deep, trian- 

 gular ; cicatrices impressed ; excavation of the palleal 

 impression small and rounded ; cavity of the shell rather 

 shallow, furnished posteriorly with two channels on each 

 valve ; margin very minutely crenulate ; nacre not pearly. 



Diam. .3, Length .4, Breadth .8, of an inch. 



Observations. Among all the nuculw I have not seen so 

 beautiful a species as this ; its fine form and adorned exte- 

 rior are very remarkable. The folds are larger before the 



* Named after the distinguished geologist Al. Brogniart. 



