188 



Distinguishing Cliaracters. — Nearly round outline; de- 

 pressed convex form ; small muscular areas, divided by 



longitudinal median septum. 



Specimens referred to this 

 species, showing the exterior 

 with beak subternunal, and con- 

 centric stri{:e, are found in the 

 Encrinal limestone, at Section 5. 

 Measurements. — Two speci- 



Impres- 



FiG. 90. Pholidops oblata. 

 sion of interior of valve in shale, showing 



double callosity : exterior of exfoliated i . i — ^ n - 



specimen, showing submarginal beak, and meUS : lengtll, i and O.O mm.; 

 a few lines of growth, Encrinal ILiiie- • -> i ,. r -y n n 



stone, X 2%. (Original.) Width, 6.6 and \y.6 miu. 



BRACHIOPODA ARTICULATA. 



Genus RHIPIDOMELLA. Oehlert. 



[Ety. : liipid. a fan; ella, diminutive.] 

 (Ortliis in part.) 



(1891: Journal de Ccuchyliologie, p. 372. 1892: Pal. N. Y., Vol. YIII., Pt. 



I., p. 209.) 



Shell almost circular in outline; both valves convex, brach- 

 ial valve more so than the pedicle valve. Hinge area nai-row 

 and short on the brachial valve, higher on the pedicle valve. 

 A slight median depression in each valve. Surface covered 

 with fine, rounded, hollow, tubular strice, which frequently 

 open upon the surface. On the interior of the pedicle valve 

 appear two strong diverging teeth. ^luscular area large, 

 and deeply impressed, consisting of the large fluted diductor 

 impressions, enclosing the small central adductors. The pedi- 

 cle scar fills the cavity of the beak. Outside of the muscular 

 area are commonly deeply-pitted ovarian markings. The' 

 interior of the brachial valve shows deep and narrow dental 

 sockets, with prominent projecting crural plates. In the 

 center is a strong cardinal process, below which is the indis- 

 tinct small muscular area. 



Rhipidomella vanuxemi. Hall. (Fig. *)1.) ( Pal. N. Y., 

 Vol. IV., p. 47, PI. yi.) 



