﻿1044 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. \2J 



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 117972b; (15) immature brachial valve, X 4, paratype, n68o8g; (16) exterior 

 of a brachial valve showing fine concentric lines of young stages and coarse ele- 

 vated ridges of older parts of shell, X 3> paratype, n68o8h; (17) another young 

 brachial valve, X 4, paratype, n68o8i; (18) exterior of a pedicle valve, X 2, 

 paratype, 117972a (for interior see pi. 28, G, figs. 27, 28) ; (19) young, elongate 

 brachial valve, X 3, paratype, 116808J ; (20) exterior of a nearly complete bra- 

 chial valve showing concentric corrugations, X 6, paratype, 116808k. 

 Horizon and locality same as preceding. 



D. Schizotreta shuleri (Willard) 280 



(21, 22) Exterior of two brachial valves showing strong concentric corrugations, 

 X 2, hypotypes, 117969a and 117969b. 



Botetourt formation, on the south side of the road, 0.2 mile east of Strasburg 

 Junction, Strasburg (15') Quadrangle, Va. 



E. Schizotreta snbconica Cooper, new species 281 



(23, 24) Exterior and interior of the pedicle valve showing the foramen, X 3. 

 holotype, 116805a; (25) a small pedicle valve, X 4, paratype, 116805b; (26) 

 small imperfect brachial valve, X 4. paratype, 116805c; (27, 28) exterior and 

 interior of a nearly perfect pedicle valve showing position of the pedicle foramen, 

 X 4, paratype, n68o5d; (29-31) respectively exterior, interior, and side views of 

 the pedicle valve showing foramen, X 3, paratype, n68o5e; (32) interior of the 

 same specimen, X 4, showing the foramen in more detail. 



Pratt Ferry formation, 0.2 mile southeast of Pratt Ferry, Blocton (15') 

 Quadrangle, Ala. 



F. Schizotreta willardi Cooper, new species 281 



(33-35) Posterior, apical, and interior views of a fragment of the pedicle valve 

 showing the foramen, posterior slope, and pedicle tube, X 3, paratype, 116806a; 

 (36) exterior of the brachial valve, X 2, paratype, 116806b; (37) another frag- 

 mentary brachial valve showing the apex and posterior margin, X 3, paratype, 

 116806c; (38) a fragmentary brachial valve showing small, low apex, X 2, 

 paratype, n68o6e; (39) fragmentary pedicle valve showing pedicle slit, X 2, 

 specimen lost; (40, 41) exterior and interior of a nearly complete but young 

 pedicle valve, X 3, paratype, n68o6f. 

 Horizon and locality same as preceding. 



Plate 22 



Acrotreta, Craniops, Obolellina, Obolus, Petrocrania, Philhedra, 

 Schizambon, Schizotreta 



A. Craniops attenuata Cooper, new species 240 



(1) Two valves, X 3, holotype, 116798. 



Carters formation (near top of massive limestone), quarry 0.3 mile north of 

 Gate City, Leeds (15') Quadrangle, Ala. 



B. Craniops trentonensis (Hall) 241 



(2) Lamellose brachial valve, X 4> figured specimen, 109788b. 

 Nealmont formation (upper 50 to 75 feet), Reedsville, Pa. 



C. Craniops tenuis Cooper, new species 240 



(3-5) Pedicle, side, and brachial views, X 8, of the holotype, 109752a. 



Bromide formation (Pooleville member — Oxoplecia gouldi zone), Rock Cross- 

 ing of Hickory Creek, about center sec. 35, T. 5 S., R. 1 E., Criner Hills, Carter 

 County, Okla. 



D. Schizotreta microthyris Cooper, new species 278 



(6, 8) Side and exterior views of a pedicle valve, X 1, paratype, 116803a; (9, 7) 

 same views, same specimen, X 2, showing ornamentation. 



