DAVIDSON — ON SOME FOSSIL BRACHIOPODA. 461 
At pages 207-218 of the third volume of the Palseontology of New 
York, Professor J. Hall has proposed two new genera, or sub-genera, 
under the names of Trematospira, and Nucleospira ; but as I am not 
acquainted with any of the species of which they are composed, and 
as the Professor's plates referring to those forms are not yet in my 
possession, all I can do at present will be to furnish extracts from the 
author's own descriptions. 
Trematospira is stated to be a Terebratula- shaped shell, with internal 
spires arranged as in Snirifera, and that the beak of the larger valve is 
truncated by a circular perforation, which is separated from the hinge-line 
by a deltidium : so far it would agree with Eetzia, but from this it is 
stated to be distinguished by external- and other characters. The 
author places great stress on the presence of a deep triangular pit 
beneath the beak of the larger valve, wfiich is filled up by the closely 
incurved beak of the opposite one ; but, as Professor Hall observes that 
the condition of the specimens was such as to prevent any satisfactory 
investigations of the interior, the genus cannot be considered as satis- 
factorily established. 
Nucleospira is stated to be spheroidal, or transversely elliptical, with in- 
ternal spires as in Sptr if era, and that the larger valve has its beak extended 
beyond the opposite one, and beneath it a triangular depression or area 
is sometimes terminated in a shallow, spoon-shaped pit ; a narrow ridge 
or septum extends along the centre of the inner side of the valve from 
beak to base ; the dorsal or smaller valve is furnished with a strong 
spatulate cardinal process, which, rising vertically from the cardinal 
margin, is closely grasped at its base by the cardinal teeth of the other 
valve, and thence, bending abruptly upwards and expanding, is pro- 
jected into the cavity of the opposite valve ; this process is grooved 
or depressed in the centre of the upper side, so as to leave between it 
and the ventral beak a narrow space for the passage of a pedicle, for 
the protrusion of which a minute foramen is sometimes observed in the 
beak. From the sides of this process, above the junction of the teeth of 
the opposite valve and at the point where it bends upwards, originate 
the brachial processes which support the spires ; a deep cavity 
beneath the cardinal process extends to the dorsal beak, from which 
arises a thin elevated septum, running to the base of the shell. 
The muscular imprints are confined to a narrow oval space. Shell- 
structure punctate, and, when perfect, covered with minute hair-like 
