292 
PALEONTOLOGY OF NEW YORK. 
contour of the shell, highly developed median septum, with the fimbriated 
descending branches of the brachidium, warrants the separation of this type 
Fig. 211. 
FIG. 212. 
Centronella (Harttina) Anna, Hall. 
Dorsal and piofile.views of a preparation of the brachidium; showing the hinge-plate, broad jugal processes, lini- 
briated descending lamellas, long recurved lamellae, and prominent median septum in the brachial valve. 
(c.) 
of structure from other known genera, from which it may be distinguished by 
the term Harttina. 
A Carboniferous species, Waldheimia Coutinhoana, with an essentially similar 
internal structure, has been described by Derby * from the Amazonas. This 
shell is rather more biconvex than Harttina Anna, and has a lesser develop¬ 
ment of the dorsal septum; together, they represent the continuance of the 
CRYPTONELLA-type of brachidium into the later palaeozoic faunas. 
* Bulletin of the Cornell Univei-sity, vol. i, No. 2, p. 3, pi. iii, fig. 22; pi. viii, fig. 6; pi. ix, figs. 1, 
2. 1874. 
