NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 63 



Table 9. — Measurements of Atribonium succiduum, 

 Potter Farm Formation, Mich. 



Measurements, in millimeters 



142000 9.8 11.0 8.2 nr. Four Mile Dam 



Occurrence and abundance. — Potter Farm Formation, pit in NW. 

 corner of Alpena Cemetery, NW. % SW. y, sec. 21, T-31-N, R-8-E, 

 Alpena County, Mich. USNM loc. 37a (89 specimens USNM 142001- 

 142003) ; Potter Farm Formation, y mile south of Four Mile Dam, 

 NW. y A , sec. 18, T-31-N, R-8-E, Alpena County, Mich. (3 specimens 

 USNM 142004) ; Potter Farm Formation, 0.25 mile south of bend in 

 road at Four Mile Dam, SE. corner NE. y A NW. y A , sec. 18, T-31-N, 

 R-8-E, Alpena County, Mich. (2 specimens USNM 142006) ; Potter 

 Farm Formation, at Potter Farm, Alpena, Mich. (1 specimen USNM 

 142005). 



Age. — Late Middle Devonian. 



Genus CAMERISMA Grant n. gen. 



(Camera, L., vaulted chamber ; erisma, L., prop) 



Laevicamera GRABAU, A. W., 1936, Paleont. Sinica, ser. B, vol. 8, ^asc. 4, p. 87. 

 Levicamera Grabau, SARYCHEVA, T. G., and SOKOLSKAYA, A. N., 1952, 



Trudy Paleont. Inst. Mosc, vol. 38, p. 171 (as subgenus of Camarophoria) . 

 NOT Levicamera GRABAU, A. W., 1934, Paleont. Sinica, ser. B, vol. 8, fasc. 3, 



p. 18 (= Psilocamara Cooper 1956a). 



Shell wall thick ; profile strongly biconvex ; outline subovate to sub- 

 pentagonal ; commissure strongly uniplicate ; fold high, arched, pro- 

 ducing blunt-crested ridge along midline of brachial valve; sulcus 

 shallow, median line with narrow trough or flattening, extending 

 around anterior as broad tongue; costae weak or absent, confined to 

 anterior of fold and sulcus, normally barely perceptible, there number- 



