BRACHIOPODA. 143 



ible. Brachial valve more or less convex, with the beak marginal. External 

 surface radiately striated. The interior bears a pair of strong posterior 

 adductor scars, lying close together in the umbonal region ; their outline is 

 elongate-ovate, indicating a progressive increase in size, and they irequently 

 appear to be divisible into anterior and posterior elements. In front of them, 

 at about the center of the valve, are the small and fsiint anterior adductor im- 

 pressions. A low median ridge extends from the apex to beyond the center of 

 the valve. External surface marked by elevated stria? radiating from the 

 beak. 



Substance of the shell composed of perlaceous calcareous laminae which 

 constitute the most of the shell. The inner layers appear to be corneous. All 

 are impunctate (?). 



Type, Schizocrania filosa, Hall. 



Observations. We have knowledge of but two clearly defined species of this 

 remarkable genus, the type, a not uncommon form in the Hudson group 

 in Ohio and Kentucky, usually occurring attached to foreign bodies, not infre- 

 quently to valves of Sfrophomena alternata; a shell often of considerable size in 

 these localities but represented in the Utica slate of New York by a rather 

 diminutive form ; and a second .species, here described under the name S. Schu- 

 cherti, from the Utica horizon of the Cincinnati group at Covington, Kentucky. 

 It was observed in the original discussion of this genus that these fossils were 

 probably parasitic or adherent by the surfaces of their lower valves, as in 

 the case of most palfBOzoic Cranias. It seems necessary to modify this 

 opinion as our present material ailbrds evidence that tlie lower surface of the 

 pedicle-valve retains its concentric markings with no trace of conformation to 

 the body to which the animal may be attached. The pedicle itself was, if we 

 may judge from the size of the aperture, of very great strength and the pedi- 

 cle-valve, being of somewhat less diameter than the brachial, was overlapped 

 by it, and it is very apparent that this overlapping edge of the upper valve has 

 formed an important accessory means of attachment. (See Plate IV g, figs. 25, 

 29, 33-35.) 



