NO. 1257. A NEW GEXUS OF ^fOLLUSKS— STANTON. 307 
EXPLANATION OF PLATES. 
Plate XXV. 
Chondrodonta inunsoni {Hill), p. 302. 
I'itr. L Lower valve of a medium-sized somewhat elongate specimen lacking nearly 
an inch of the umbonal portion and cut across the lower part of the hinge. 
2. View of the upper end of specimen represented by tig. 1, polished to show 
transverse section of the two valves and their chondrophores. 
8. A similar section across the lower part of the hinge of the same specimen at 
the cut shown in tig. 1. 
4, 5. Opposite views of a small specimen showing sculpture of the same strength 
on both valves. 
(The specimen represented by tigs. 1-3 has the upper valve nearly smooth. ) 
Plate XXVI. 
Chondrodonta glafn-a, new species, p. 305. 
Fig. 1. Exterior of a small attached valve. (The striations on the lower portion are 
accidental, due to slight slipping movements of the rocks. ) 
2. Interior of same, showing the hinge and the pallial line; pp, palUal impression; 
H, chondrophore of lower valve; cu, broken edge of chondrophore of the 
•upper valve still adhering in the groove of the lower valve. At its broken 
distal extremity it may be seen curving under the other chondrophore. 
3. Cross section of lower part of the hinge of a larger specimen. 
I 
