OF CONCHOLOGY. 167 



7. Oholella chromatica, Bill., from Billings. 



8. Centronella, Bill. ; showing the loop. 



9. Loop of Magasella (? var.) Icevis, Dall. ; twice nat. size. 



10. Side view of same, enlarged. 



11. Profile of apophyses of ? 3Iagas 'patagonica, Gld. ; en- 

 larged twice nat. size. 



12. Interior of hsemal valve of the same enlarged one-half, 



13. Magasella (? var.) Icevis, Dall. ; twice nat. size. 



Plate 7. 



Fig. a. Interior of neural valve of Waldheimia Eaphaelis, Dall., 

 showing muscular impressions. 



b. Interior of haemal valve of do., nat. size. 



c. Side view of Waldheimia Raphaelis, Dajl. ; nat. size. 



d. Anterior view of do. 



e. Profile of loop of do., with one of the crura and part of 



the left haemal process removed, to show outline of 

 septum. 



f. Haemal valve of Laqueus californicus, showing the loop; 



reduced" to one-half nat. size. 



g. Profile of loop of Laqueus suffusiis, Dall ; magnified 



three times, linear. 



h. Laqueus suffusus, Dall., nat. size. 



s. Interior of haemal valve of do., magnified. 



Plate 8. 

 Fig. 1. Glottidia albida, Dall. ; nat. size. 



2. " " " interior of neural valve, nat. 

 size. 



3. a, section of do. near beak, magnified, b, c, section of 



lamellae. 



4. Section of lamella magnified 500 diameters, showing 



the dark horny layers and white calcareous layers. 



5. Section of thickest part of valve, same power, showing 



the layers. 



6. Section of external horny layer, magnified 900 diame- 



ters, showing fibrous structure. 



