224 



Distinguishing Characters. — Robust character; size; 

 '•shouldered" expression; greater convexity of brachial 

 valve; " nasute " front, caused by deep sinus ; coarse surface 

 lamellae; outline of muscular impressions. 



Found iu the upper Moscow shale, two feet below the 

 Styliolina band, at Section 3 (very rare); lower Moscow 

 shale, at Sections \ and 5 (common); Encrinal limestone, 

 at Section 5 (common); Lower shales (fairly common below 

 the Demissa bed, abundant nine feet below the Encrinal lime- 

 s t OH e — A spiriferoides bed); also twenty feet below the 

 Encrinal ; also in the Modiomorpha subalata bed ; it is again 

 abundant intheshale between the lower and middle Trilobite 

 la vers; and occurs as low as the Nautilus bed, and the 

 shales below it. 



Genus MERISTELLA. Haul. 



[Ety. : Diminutive of Merista ; meros, apartment (chamber).] 



(1860 : 13th Rep't N. Y. State Cab. Nat. Hist., p. 74. 1893: Pal. N. Y., 



Vol. VIII., Pt. II., p. 73.) 



Shell unequally biconvex, often inflated, varying from 

 transverse to elongate in outline; cardinal areas obscure. 

 Anterior margin sinuate, caused by sinus and fol.d, which 

 appear only near the front of the shell. Umbo of the pedicle 

 valve incurved at maturity, concealing most, if not all, of 

 the foramen. Teeth strong, supported by lamellae; deep, 

 sub-triangular muscular impression in pedicle cavity. In 

 the brachial valve a median septum supports the hinge 

 plate, and extends for somewhat more than one-third the 

 length of the shell. Brachidium a spire. 



Fie 184. Meristella huskiusi. Dorsal, profile, and ventral views of a specimen (from 

 Hall). 



