BRACHIOPODA. 116 



The Uncites lavis, McCoy,* has been generally regarded by the best authori- 

 ties as an imperfect or exceptional form of Stringocephalus. In 1879, Dr. 

 (Ehlert described! a species, U. Galloisi, with a smooth exterior, from the Mid- 

 dle Devonian of Maine-et-Loire, France. 



Uncites is allied in its form, external ornament, coalesced deltidial plates, 

 position of the spirals and the form of the loop, to the retzioid genera, but it 

 differs widely in some important particulars. McCoy placed the genus in a 

 family by itself; Zittel and CEhlert have included it with many other dis- 

 tantly related genera under the family Spiriperid^. Davidson, in his " General 

 Summary " (p. 354), placed it by itself in a doubtful subdivision of this 

 family, while Waagen has included it in his Uncitina, a subfamily of the hetero- 

 geneous group, NacLEospiRiD^, of Davidson. 



The genus Uncites has not been recognized in North America. 



Gends EUMETRIA, Hall. 1863. 



PLATE LI. 



1858. RttzlOy Hall. Transactions of the Albany Institute, vol. iv, p. 9. 



1858. Retzia, Hall. Geology of Iowa, vol. i, pt. 2, pp. 657, 704, pi. xxiii, fig. 1 ; pi. xxvii, fig. 3. 



1863. Euinetria, Hall. Sixteenth Ann. Kept. N. Y. State Cab. Nat. Hist., p. 55, figs. 1-3 j p. 59. 



1882. Euinetria, Whitkikld. Bull. American Museum Nat. Hist., vol i, p. 50, pi. vi, figs. 28-30. 



1883. Eumeti-ia, Hall. Twelfth Ann. Rept. State Geologist Indiana, p. 335, pi. xxix, figs. 28-30. 



Diagnosis. Shells elongate-terebratuliform ; outline ovate. Valves sub- 

 equally convex. Hinge-line short ; cardinal area of the pedicle-valve some- 

 what elevated, primarily composed of symmetrical deltidial plates. In the 

 adult condition the line of symphysis between these plates is lost, or repre- 

 sented by a faint line, giving the deltidium the appearance of a single vertical, 

 or slightly incurved plate, sharply defined on its lateral margins. The foramen 

 is apical, only its lower side encroaching on the deltidium. The cardinal ex- 

 tremities are slightly alate, a feature more noticeable on the brachial valve and 

 which gives this valve a somewhat pectenoid appearance. On the interior of 

 the pedicle-valve the teeth are of moderate size, but otherwise the shell is 



•British Paleozoic Fossils, p. 380, pl. Wa, fig. 6, 1852. 



t Corapte.i rendus Soc. g6ol. ; more fully discussed and illusti-ated in Annalea de Sciences geologiques, 

 1880 ; author's copy, p. 5, pl. iv, figs. 1-4. 



