187 



opening; position of apex variable; the edges of the valves 

 are flattened where they join, and on the interior are elevated 

 areas for the attachment of the muscles, etc. In molds of 

 the interior, a strongly-marked impression of this callosity 

 appears. 



Pholidops hamiltoxl-e. Hall. (Fig. 88.) ( Pal. N. Y., 

 Vol. IV., p. 32.) 



Distinguishing Characters. — Small size; ovate outline; 

 broader posterior end; eccentric, elevated apex, inclined 

 backwards; lamellose lines of growth closely arranged. 



twfil* 



Fig. 88. Pholidops hamiltonice. Interior of ventral valve, x 8; impressions of interiors 

 of ventral and dorsal valves, x 8; exterior of shell, x 4 (from Hall). 



width, 3 mm. 

 (Fig. 89.) (Pal. N. Y., 



Found as single valves, molds, etc., and is common 

 throughout the Hamilton shales, from the Trilobite beds 

 upward. It occurs in the lower Moscow shale, at Sections 

 4 and 5. 



Measurements. — Length, 4 mm. 



Pholidops lixguloides. Hall. 

 Vol. IV., p. 414.) 



Distinguishing Characters. — Linguloid outline; projecting 

 apex, with flattened "area," stri- 

 ated by lines of growth. 



Found in theEncrinal limestone 

 and the Demissa bed, at Section 5. 



Measurements. — Two speci- 

 mens: length, 7 and 7.7 mill.; ™lve, showing form, false area, and 

 ° muscular callosities, Encrioal lnne- 



width, 5.2 and 6.9 mm. 



Fig. 89. Pholidops linguloides. In- 

 terior and exterior of a ventral (:-) 



stone, x 2%. (Original ) 



Pholidops oblata. 

 IV., p. 414, PL III.) 



Hall. (Fig. 90.) (Pal. N. Y., Vol. 



