14 DESCRIPTION OF 



.III 



. 

 r 



PLATE XIII. 



Pas>e 



Fig. 1. SriRIFER FORBESI. 600 



1. A ventral valve from which the surface markings have been worn. 



Fig. 2. SPIRIFER IMBREX. 601 



2. Dorsal valve of a specimen of this species. 



Fio-. 3. SPIRIFER INCERTTTS. 602 



' O 



3. Cardinal view of the specimen, showing the linear area. 



Fi<r. 4. SPIRIFER PLENUS. 608 



O 



4 a. Ventral view of a specimen of this species. 

 4 b. Dorsal view and area of same. 

 4 c. Front view of same. 



4 d. Profile view (the heak of the ventral valve is represented too little 

 arcuate) . 



4 e. Interior of ventral valve. 



