l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



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 terior view of an adult brachial valve shovi^ing fully matured 

 loop, X 2, paratype U.S.N.M. No. 124195. 35, The preceding 

 loop enlarged, X 4, to show mode of attachment to crural 

 bases and socket ridges, and showing the small inner hinge 

 plates. 36, Interior of another specimen tilted to side with 

 brachial valve broken off and showing loop with two trans- 

 verse bands, X 2, paratype U.S.N.M. No. 124195a. 37, Same 

 specimen tilted away from observer to show the two trans- 

 verse bands, X 3- Horizon and locality same as above. 



Plate 2 



A. Gemviarcida arizonensis Cooper, new species 7 



1-5, Anterior, posterior, side, brachial, and pedicle views, re- 

 spectively, of a complete specimen, X i, paratype U.S.N.AI. 

 No. 124197b. 6-10, Brachial, side, posterior, anterior, and pedi- 

 cle views, respectively, X 2, of holotype U.S.N.M. No. 124197a. 

 II, Complete specimen tilted to show interarea and deltidium 

 (= united deltidial plates), X 3. paratype U.S.N.M. No. 

 I24i97d. 12, View of the interarea and disjunct deltidial plates 

 of a young specimen, X 3, paratype U.S.N.M. No. I24i97g. 

 13, Posterior part of a pedicle valve tilted to show callosity 

 on floor of delthyrial cavity, low median septum, and discrete 

 deltidial plates, X 2, paratype U.S.N.M. No. I24i97h. 14, Im- 

 mature pedicle valve, X 4, showing deltidial plates just form- 

 ing and callosity on floor of delthyrial cavity, paratype 

 U.S.N.M. No. 124201a. 15, Interior of an incomplete brachial 

 valve, X 3. paratype U.S.N.M. No. i2^igyt, showing cardi- 

 nalia. 16, Interior of a brachial valve younger than the preced- 

 ing. X 4, showing cardinalia, paratype U.S.N.M. No. I24i97f. 



17, Interior of an old specimen showing deeply excavated 

 notothyrial callosity simulating a concave hinge plate, crura 

 and crural processes, X 3, paratype U.S.N.M. No. 1241971. 



18, 19, Tilted and interior views of a young brachial valve 

 showing hooded pre-campagiform stage of loop, X 4, para- 

 type U.S.N.M. No. 124199. 20, Interior of the pedicle valve 

 of the preceding specimen, with open delthyrium, X 4- 21, A 

 young specimen, X 4, showing beginning of ring and attach- 

 ments of descending lamellae of loop, paratype U.S.N.M. No. 

 124198a. 22, A still larger specimen than the preceding show- 

 ing deeper cleft in remnant of ring, X 4, paratype U.S.N.M. 

 No. 124198b. 23, Young brachial valve tilted to show cleft in 

 loop ring, X 4, opposite to pedicle valve shown in figure 14, 

 paratype U.S.N.M. No. 124201b. 24, Specimen with pedicle 

 valve partially removed to show attachment of loop to septum 

 and long anterior branches of the descending lamellae, X 2, 

 paratype U.S.N.M. No. 124197J. Mural limestone, from a 

 small hill 300 yards east of U. S. Highway 80, NWiSWi- 

 NEi sec. 36, T. 23 S., R. 25 E., Bisbee Quadrangle, Cochise 

 County, Arizona. 



