NO. 4 CRETACEOUS BRACHIOPODA, ARIZONA — COOPER 1 7 



Page 

 25-28, Interior, posterior, side tilted, and interior posteriorly 

 tilted views, resijectively, of an adult specimen showing 

 terebrataliform loop, X 2, paratype U.S.N.M. No. 124220. 

 Mural limestone, Rancho Nuevo, 3 miles east of Santa Ro- 

 salia, Sonora, Mexico. 



B. Gemviarciila mcnardi (Lamarck) 10 



29, 30, Brachial and side views of a complete specimen, X ii 

 for comparison with Gemmarcula arisonensis, hypotype 

 U.S.N.M. No. 124223c. 31, Interarea of the pedicle valve, X 2, 

 showing symphytium (or deltidium), teeth, and foramen, 

 hypotype U.S.N.M. No. 124223a. :i2, 2i2, Interior and pos- 

 terior views of the brachial valve showing complicated car- 

 dinal process, X 2, hypotype U.S.N.M. No. 124223b. 34, 

 Brachial interior showing part of loop, X 2, for comparison 

 with G. arisonensis, counterpart of pedicle valve shown by 

 figure 31. Cretaceous (Green Sand), Le Mans, Sarthe, France. 



Plate 3 



A. Craniscu^ hesperin^ Cooper, new species 2 



I, 2, Brachial and side views, X i, of holotype U.S.N.M. No. 

 124192. 3, Interior of the preceding, X 2, showing transverse 

 muscle scars. Mural limestone, from a small hill 300 yards 

 east of U. S. Highway 80, NWiSW^NEi sec. 36, T. 23 S., 

 R. 25 E., Bisbee Quadrangle, Cochise County, Arizona. 



B. Psilothyris occidentalis Cooper, new species 11 



4-8, Anterior, posterior, side, brachial, and pedicle views, respec- 

 tively, X 2, of holotype U.S.N.M. No. 124191. 9, 10, Brachial 

 and anterior views of another individual, showing uniplicate 

 anterior commissure, X i, paratype U.S.N.M. No. 124190a. 11, 

 Side view of a specimen broken to show descending branches 

 of the long dalliniform loop and part of the wide ascending 

 branch, X 2, paratype U.S.N.M. No. 124202a. 12, Interior of 

 the pedicle valve showing deltidium (united deltidial plates), 

 submesothyrid foramen, and teeth, paratype U.S.N.M. No. 

 124190C. 13, 14, Two small specimens in pre-campagiform 

 stage, X 4, showing the median septum and pillar of an early 

 juvenile stage, paratypes U.S.N.M. No. I24202e, d. 15, An- 

 other juvenile specimen in the same stage as the preceding 

 showing part of descending branch attached to pillar, X 4. par- 

 atype U.S.N.M. No. I24202h. 16, Another juvenile specimen, 

 probably in frenuliniform .stage, tilted slightly to the side and 

 showing descending branches attached to pillar and part of 

 loop ring, X 4, paratype U.S.N.M. No. I24202g. 17, Imma- 

 ture specimen in terebrataliform stage showing descending 

 branches of loop attached to median septum and the deep cleft 

 at the anterior of the loop, X 4, paratype U.S.N.M. No. 

 I24202i. 18, A specimen older than the preceding and in the 

 dalliniform stage showing receded median septum but rem- 

 nants of processes of attachment on the descending branches 



