NIAGARA FALLS AND VICINITY 201 



Genus tremato3pira Hall 



[Kty.: Tfr/^fia, foramen; ^-cT/va, spire] 



(1859. A^. Y. state vius. nat. hist. 12th an. reft, p. 27; 1893. Pal. 

 N. Y. V. 8, pt 2, p. 124) 



Shells transverse, with siibequally convex valves; surface radially 

 plicate; hinge line straight, cardinal extremities abruptly rounded; 

 anterior margin sinuate. Pedicle valve with a median sinus and an 

 incurved beak, truncated by a circular foramen. Delthyrium cov- 

 ered by two short incurved plates, which are usually closely an- 

 kylosed, and appear continuous, with a narrow, flattened area on 

 either side; lower half of the delthyrium open, for the reception of 

 the beak of the brachial valve. Teeth prominent, arising from the 

 bottom of the valve; above the hinge line they curve backward and 

 toward each other, thus making a very firm articulation. Muscular 

 area well defined. Brachial valve with median fold, and minute 

 beak. Hinge plate greatly elevated, with a small chilidium resting 

 against it; upper face of plate deeply divided by median longitudinal 

 groove, and more faintly by transverse groove. Dental sockets 

 small and deep, crura broad, thin and comparatively short. Brachi- 

 dium of two spiral cones set base to base, as in S p i r i f e r . 



Trematospira camura Hall (Fig. 

 122). Atrypa camura Hall (1852. 

 Pal. N. Y. 2:273, pi. 56) "^1^^ .4^, 



Distinguishing characters. Small ; 

 subrhomboidal to transversely elon- 

 gate; nearly equally convex valves. 

 Small, acute, proiectins: and slip"htlv in- 



^ -^ "^ o . pjg^ J23 Trematospira camura 



curved beak of pedicle valve, showing 



in young shells the ankylosed deltidial plates; strong, distant, simple 

 subangular plications, one or two fine ones in the center; fine, 

 thread-like concentric striae and coarse lamellae. 



Found in the Bryozoa beds of the Rochester shale at Niagara, 

 rather common. Also at Lockport and elsewhere (Hall). 



Genus whitfieldella Hall & Clarke 



[Ety. : proper name] 



(1893. Pal. N. Y. V. 8, pt 2, p. 58) 



Shells usually of small size; valves subequally convex, ovate or 

 elongate in outline; beak of pedicle valve not high or greatly in- 



