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 intei'ior, a strongly-marked impression of this callosity 

 appears. 



Pholidops hamiltoni.i^. Hall. (Fig. 88.) (Pal. N. Y., 

 Vol. lY., p. 32.) 



Distinguishing Clninicters. — Small size; ovate outline; 

 broader 2)osterior end; eccentric, elevated apex, inclined 

 backwards; lamellose lines of growth closely arranged. 



Fig. 88. Pholidops hamiltonioe. Interior of ventral valve, x 8: impressions of interiors 

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



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. ; width, 3 ram. 



Pholidops linguloides. Hall. (Fig. 89.) (Pal. N. Y., 

 Vol. IV., p. 414.) 



Distinguishing Characters. — Linguloid outline; projecting 

 apex, with flattened "area," stri- 

 ated by lines of growth. 



Found in theEnci'inal limestone 

 and the Demissa bed, at Section 5. 



Me a s urement s. — Two speci- fio. 89. Phouciops unguiotdes. in- 



, , „ T ^ _ terior and exterior of a ventral (?) 



mens: length, i and l.i mm.; valve, showing form, false area, and 



muscular callosities, Eucrinal lime- 



width, 5.2 and 6.9 mm. stone, x 2?^. (Original.) 



Pholidops ORLATA. Hnll. (Fig. 90.) (Pal. N. Y., Vol. 

 IV.,p. 414, PL III.) 



