﻿1094 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 12J 



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 showing musculature and rudimentary pseudodeltidium, X 3, holotype, 91344a ; 

 (9) brachial interior showing thick delthyrial platform and bladelike cardinal 

 process, X 3, paratype, 91344^ (10) brachial interior turned to the side to show 

 brachiophore supports, fulcral plate, and socket, X 4, paratype, 91344b; (11) 

 another brachial interior showing cardinal process, X 2, paratype, 91344J ; (12) 

 brachial exterior, X 2, paratype, 91343d; (14, 15) views of the interarea and 

 interior of the pedicle valve showing pseudodeltidium, teeth, and crural fossette, 

 X 4, paratype, 9*344k. 



Upper Pogonip group {Desmorthis zone), west end of Lone Mountain, 

 18 miles northwest of Eureka, Roberts Mountains (i°) Quadrangle, Nev. 

 (5) Pedicle exterior, X 2, figured specimen, 110806a. 



Joins formation, SWi sec. 2, T. 1 S., R. 1 W., about 4 miles east of Hennepin, 

 Murray County, Okla. 



B. Plectorthis symmetrica Cooper, new species 453 



(16-20) Respectively brachial, posterior, pedicle, side, and anterior views, X 2, 

 of the holotype, 110824a; (21) brachial interior, X 2, paratype, 110828a. 



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

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

 Hills, Carter County, Okla. 



C. Plectorthis ponderosa Cooper, new species 451 



(22-24, 28) Respectively pedicle, brachial, side, and anterior views of a small indi- 

 vidual, Xii paratype, 110837b; (25-27) posterior, brachial, and pedicle views of 

 a large specimen, X I, paratype, 110837a; (29) plasticine replica of the brach- 

 ial interior, X T ^, paratype, no837d; (30) impression of the brachial interior, 

 X 1, from which the preceding replica was prepared; (31) impression of the 

 pedicle interior, X 1, prepared by burning shell, paratype, 110837c; (32) replica 

 of posterior part of pedicle interior, X 2, prepared from preceding impression. 

 Martinsburg formation (basal part with Brongniartella referable to Salona 

 formation), on Virginia County Highway 617 = 910, 0.15 mile north of Green 

 Mount Church, Broadway (15') Quadrangle, Va. 



Plate 84 

 Plectorthis 



A. Plectorthis transversa Cooper, new species 454 



(1-5) Respectively brachial, posterior, side, anterior, and pedicle views, X 1, of 

 the holotype, 98181. 



Arline formation, quarry on north side of Marion, Marion (T.V.A. 218-SE) 

 Quadrangle, Va. 



B. Plectorthis compacta Cooper, new species 448 



(6-10) Respectively pedicle, brachial, side, posterior, and anterior views of a per- 

 fect specimen, X 1, holotype, 1 10821 r; (11-13) respectively posterior, brachial, 

 and pedicle views, X 1, of a larger paratype, 110821s; (14) pedicle interior, X 2, 

 paratype, 110821-0; (15) brachial interior of a young specimen, X 2, paratype, 

 11082m; (16) brachial interior of a larger specimen than the preceding, X 2, 

 paratype, no82iq; (17) posterior of preceding enlarged, X 3, to show details of 

 cardinal ia. 



Arline formation (near middle), north side of wagon road in glade, \ mile 

 southeast of Friendsville, Concord (T.V.A. 138-SW) Quadrangle, Tenn. 



C. Plectorthis sp. 2 455 



(18) Brachial interior, X 2, figured specimen, 110835a. 



Murfreesboro formation (top), from excavation of new armory building at 



