300 



PALEONTOLOGY OF NEW YORK. 



Flc. 223. Seecheria [Hemiptychina) subtatis, Waageii. 

 Dorsal view; showing the smooth exterior. 



(Waagen.) 



single form) of smooth species without dental plates. It is here proposed to 

 separate these shells from Hemipty- 

 china and to distinguish them by 

 the term Beecheria,* giving a brief 

 account of the interior structure as 

 exemplified in B. Davidsoni, sp. nov.,f 

 of the Carboniferous limestone of 

 Windsor, Nova Scotia. 



The general character of the interior is that of Dielasma, except that the 

 dental plates are wholly absent or represented only by faint ridges which 

 never reach the bottom of the pedicle- 

 valve. The peculiar myiferous hinge- 

 plate of Dielasma is wholly merged 

 with the valve, but the crural ridges 

 are still retained and the descending 

 lamellae originate from them at the 

 bottom of the valve in very much the 

 same way as in Dielasma. The crural apophyses are broad and erect, there 

 being no part of the descending branches behind them. Sometimes the 

 brachial valve retains a low muscular impression which has the form of 

 the platform of Dielasma, This species and Beecheria {Hemiptychina) sublavis, 

 Waagen, constitute the known representatives of this type of structural 

 variation. 



Fio. 224. Beecheria Davidsoni, Bp. nov. 

 An enlarged profile oi" the brachidium; showing the man- 

 ner in which lamellse arise from the bottom of the valve, 

 the broad posterior jugal processes and the much nar- 

 rower descending lamella. The anterior transverse or 

 reflected band is not fully retained. (c ) 



Genus CRYPTACANTHIA, White and St. John. 1867. 



1867. Waldheimia? (Cryptacanthia), White atid St. John. Trans. Chicago Academy of Sciences, 

 vol. i, [it. i, p. 119, fig-. 3. 



Our knowledge of this genus is still very imperfect. The authors described 

 as Waldheimia? compacta, a rather small, plano-convex or naviculoid shell from 



* In recognition of his important contributions to our knowledge of the Bi-achiopoda. 

 t This is the shell identified by David.son as Terebratula saccidus, Martin. (On the Lower Carboniferous 

 Brachiopoda of Nova Scotia; Quart. Journ. Geol. Soc, vol. xix, p. 169, pi. ix, tigs. 1-3, 1863.) 



