EXPLANATION OF PLATE XV. 



Fig. 1. Inoceramus defouiiis. (Page 179.) 



a. Exterior view of left valve, showiug portion of the test. 



I). Section of the test of a large example, showing its prismatic strncture and great thicken 

 ing at the borders. 

 Fig. 2. Ostijea cortex. (Page 170.) 



a. Exterior pf upper valve. 



b. Interior of the same. 



c. Interior of lower valve, showing hinge and area. 

 Fig. 3. Inoceraiics fragii.is. (Page 178.) 



a. Ilight valve. 

 Fig. 4. Li.ngula. subspatula. (Pago 1G9.) 



a. Dorsal valve. 

 Fig. 5. Serpula intrica. (Pago 205.) 



a. Example, twice enlarged, showing unusual contortion. 



