Braehiopoda of the Cindnnati Group. 39 



scars of the adductor muscles moderately distinct, the posterior pair 

 being situated close back under the brachial processes, one on each 

 side of a well defined rounded ridge, that becomes suddenly smaller 

 between the anterior pair; cardinal process rhombic subconical, 

 moderately prominent, and having its posterior sides marked by deeply 

 impressed, divaricating strise ; sockets well defined ; brachial processes 

 rather strong, and directed obliquely forward and laterally, internal 

 sm-face, excepting the radiately striated front and lateral margms, 

 nearly smooth. 



Ventral valve a little convex at the umbo and flat, or slightly con- 

 cave, between the umbo and the front and lateral margms, but 

 sometimes having a low, very obscure, mesial elevation toward the 

 front ; beak small, and very short, or scarcely equaling that of the other 

 valve, arched at the apex, but not strongly incurved ; area about twice 

 as high as that of the other valve, well defined, tapering rather rapidly 

 toward the lateral extremities, arched with the beak, and directed 

 backward and downward at decidedly less than a right angle to that of 

 the other valve ; foramen broad, triangular and partly occupied by the 

 cardinal process of the other valve. Interior with muscular scars, 

 occupying a rather deep, bilobate impression, extenduig nearly or quite 

 to the middle of the valve, and usually defined by a low ridge most 

 distinct on each side ; scars of adductor muscles small, separated by a 

 mere trace of raised line ; those of the divaricator muscles of moderate 

 size longitudmally striated, and having their narrowed ends extending 

 backward, nearly to a small triangular, transversely striated space, 

 occupying the mterior of the beak ; those of the ventral adjuster mus- 

 cles smaller and shorter than the divaricators, and situated nearly 

 under the hinge teeth, which are moderately prominent, subtrigonal 

 and oblique ; vascular markings with their lateral divisions curving up 

 backward, and sending ofi* several branches, while the other divisions 

 extend forward and bifurcate so as to occupy the anterior region ; 

 anterior and lateral margms crenate within by very short strife. 



Surface of both valves ornamented by moderately stout, radiating 

 striffi, the posterior lateral of which curve so strongly that a few of 

 them run out on the cardinal edge before reaching the lateral margins ; 

 strise of ventral valve nearly always increasing by bifurcation (some of 

 them dividing two or three times) ; while those on the dorsal valve 

 generally increase by the intercalation of shorter ones, between the 

 longer. A few distinct subimbricatmg marks of growth are sometimes 

 seen toward the front and lateral margins ; while on perfectly preserved 

 specimens the radiating strise may sometimes be seen to be rough- 

 ened by minute, elevated, concentric Imes, that are more or less 

 interrupted in crossing some of the strise. 



