DAVIDSON — ON SOME FOSSIL BRACHIOPODA. 461 



At pages 207-218 of the third volume of the Palaeontology of New- 

 York, Professor J. Hall has proposed two new genera, or sub-genera, 

 under the names of Trematos])ira and Wucleospira ; 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 Spirifera, 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, which 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. 



Nuoleospira is stated to be spheroidal, or transversely elliptical, with in- 

 ternal spires as in Spiriferay 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. Prom 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 



