290 PALEONTOLOGY OF NEW YORK. 



Test tliin, linely striated concentrically, with rarely any evidence of 

 fasciculation. 



Anterior muscular impression large, situated just within the anterior 

 margin of the shell. Posterior scar superficial. 



A specimen of medium size has a length of 20 mm., and a height of 14 

 mm. A more elongate form has a length of 20 mm., and a height of 12 

 mm. A large symmetrical specimen has a length of 30 mm., and a height 

 of 20 mm. 



This is a small species of quadrangular form, but subject to much varia- 

 tion in its proportions, depending chiefly on the manner in which the lateral 

 compression has been directed, whether in the line of the longitudinal or 

 vertical axis of the shell ; those lying in one direction on the surface of the 

 shale being lengthened, and those at the right angles being considerably 

 widened and shortened. 



This species differs from any of the foregoing in its small size, quadrangular 

 form, well-defined, straight, sub-angular umbonal ridge. The specimens, although 

 imbedded in a fine micaceous sandy shale, have had their surface characters 

 almost entirely destroyed by the deposition of sand, which has become incorpo- 

 rated with the shell, giving the surface a roughly granulose texture. 



Formation and localities. In the micaceous sandy shales of the Chemung 

 group, at Belmont and Rocicville, in Alleghany county ; and in Cattaraugus 

 county, N. Y. 



MODIOMORPHA NEGLECTA. 



PLATE XM, FIG. 13. 



Modlomorpha neglecta. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 41, figs. 12, 13. 1883. 



(Fig'. 12 in eri-or.) 



Shell small, ovate, wider behind ; length and height as 3 to 2 ; basal margin 

 straight in the middle, curving abruptly both at the anterior and posterior 

 extremities ; posterior margin regularly rounded, curving into the cardinal 

 margin, which is gently arcuate. Anterior end very short, declining abruptly 

 from the beaks, and regularly rounded below ; obscurely limited by a depres- 

 sion extending from the beaks to the basal margin. 



