BRACHIOPODA. 
313 
Genus CHONETELLA, Waagen. 1884. 
1884. Chonetella, Waagen. Mem. Geol. Survey of India; Palseontologia Indica, Series xiii, vol. i, 
No. 4, p. 657, pi. lxxxi, figs. 3-8. 
Diagnosis. Shell small, normally concavo-convex. Surface rounded, with 
radial striae; cardinal area narrow; deltidium, cardinal spines and teeth as in 
Chonetes. In the pedicle-valve the adductor impressions are elongate, and are 
partially enclosed by the larger cardinals. The brachial valve has a small 
trilobed cardinal process, which is continued into a low median septum. The 
muscular area is quadripartite and very distinct. The 
brachial ridges are sharply defined and appear to origi¬ 
nate near the outer extremities of the posterior adduc¬ 
tors, making a broad outward, and a more abrupt inward 
curve completing one volution. Surface in the pallial 
region strongly papillose. 
Type, Chonetella nasuta, Waagen. Upper Carboniferous. 
Observations. Dr. Waagen has proposed this division for a single species 
from the Productus limestone of India. Aside from the broadly curved brachial 
ridges, its characters are so strongly chonetoid as to render its separation from 
Chonetes exceedingly difficult.* The author surmises that some small shells 
figured by Davidson! and regarded by him as varieties of Productus longispinus, 
from the Carboniferous* shales of Lanarkshire, Scotland, belong to the same 
group. 
* The trilobed cardinal process is described in its anterior aspect only, and it is quite probable that upon 
its posterior face it would be found more similar to that of Chonetes. The crural plates are very obscure, 
making the process appear free and erect; but this is also true of some species of Chonetes, e.g., Chonetes 
coronata. Conrad. 
t Carboniferous Brachiopoda, pi. xxxv, figs. 18. 19. 
Pig. 26. Chonetella nasuta. 
After Waagen. 
