PRO. — PTE.] 



LAMELLIBRANCHIA TA. 



505 



end rounded or subtruncate, with 

 a deep notch in the antero-ven- 

 tral margin ; posterior end rounded, 

 lanceolate, or truncate; cardinal line 

 straight or slightly arcuate ; cardinal 

 slope sometimes subalate ; umbonal 

 slope rounded, undefined or subangular ; 

 surface concentrically lined. Type P. 

 elegans. 

 alata, Hall, 1885, Pal. N. Y., vol. 5, p. 



461, Chemung Gr. 



elegans, Meek, 1871, Am. Jour. Conch., 



vol. 7, p. 5, Coal Meas. 

 exuta, Hall, 1885, Pal. N. Y., vol. 5, p. 



462, Chemune Gr. 



lanceolata, Hall, 1883, Pal. N. Y., vol. 5, 



pi. 76, figs. 2 to 8, Ham. Gr. 

 meeki, Winchell, 1875, Ohio Pal., vol. 2, 



p. 305, Waverly Gr. 

 planulata, Hall, 1883, Pal. N. Y., vol. 5, 

 pi. 76, fig. 1, Ham. Gr. 

 Peotomya, Hall, 1885, Pal. N. Y., vol. 5, p. 

 52. [Ety, protos, first ; Mya, a genus.] 

 Equivalve, inequilateral, elongate, 

 ovate-elliptical ; anterior end broadly 

 rounded ; posterior end narrower, 

 rounded ; beaks incurved ; umbo 

 prominent ; cardinal line long, nearly 

 straight ; umbonal slope gibbous above, 

 not defined below ; surface concentric- 

 ally lined ; ligament external ; mus- 

 cular impressions circular ; anterior one 

 strong and near the margin. Type P. 

 oblonga. 

 oblonga, Hall, 1885, (Cardiomorpha ob- 

 longa,) Pal. N. Y., vol. 5, p. 509, Ham. Gr. 

 Pseudomonotis, Bey rich, 1862, Zeit. der 

 Deutsch., Geol. Gesselsch., vol. 14. 

 [Ety. pgeudes, false ; Monotis, a genus.] 

 Suborbicular, plano-convex, left valve 

 convex, right valve flat or slightly con- 

 cave ; not auriculate ; beaks subcentral, 

 slightly oblique, unequal, left elevated, 

 gibbous, incurved, right small; hinge 

 short, narrow, edentulous ; cartilage 

 cavity under the beaks ; byssal notch 

 of right valve narrow, deep, and 

 separated from the hinge by a small 

 rudimentary ear, which does not pro- 

 ject beyond the margin ; adductor mus- 

 cular 3car large, subcentral ; impres- 

 sions of retractor 

 muscles, several, 

 small, placed 

 near the beaks; 

 surface radiated, 

 most distinct on 

 the left valve, 

 hawni, Meek & 

 Hayden, 1858, 

 (Monotis haw- 

 ni,) Trans. Alb. 

 Inst., vol. 4, p. 

 76, and Pal. Up. 

 Mo., p. 54, Up. 

 Coal Meas. 

 hawni var. ovata, Meek & Hayden, 1865, 

 (Eumicrotis hawni var. ovata,) Pal. Up. 

 Mo., p. 55, Permian Gr. 



Fig. 901.— Pseudomonotis 

 hawni. 



hawni var. sinuata, Meek & Worthen, 

 1866, (Eumicrotis hawni var. sinuata,) 

 Geo. Sur. 111., vol. 2, p. 338, Up. Coal 



radialis, (?) Phillips, 1834, (Pecten radi- 

 alis,) Encyc. Meth., vol. 4, Coal Meas. 

 Pterinea, Goldfuss, 1826, Germ. Petref. 

 [Ety. pteron, a wing.] Transversely 

 trigonal, oblique, inequivalve, very in- 

 equilateral, left valve most convex, 

 beaks near the small anterior end ; 

 hinge-line long, straight, forming a 

 small anterior and large falciform pos- 

 terior wing, with a linear, flattened, 

 marginal cartilage facet, longitudinally 

 striated ; shell thick, calcareous ; two 

 long, slightly diverging, posterior, lat- 

 eral teeth, beneath the hinge in one 

 valve and one in the other ; a few 

 short, cardinal teeth radiating beneath 

 and in front of the beaks ; anterior im- 

 pression very strong just in front of the 

 beak, posterior impression larger, but 

 faintly marked, superficial ; pallial scar 

 simple ; shallow byssal concavity. Type 

 P. lsevis. 



Fig. 902.— Pterinea demissa. 



appressa, Conrad, 1838, Ann. Rep. N. Y. 



Not defined. 

 arenacea, Hall, 1877. Proposed, but not 



defined. ~J£Z£ 



aviformis, Conrad, 1842, (Avicula avi- 



formis,) Jour. Acad. Nat. Sci., vol. 8, p. 



243, Trenton Gr. 

 avis, Hall, 1884, Pal. N. Y., vol. 5, pt. 1, 



p. 105, Chemung Gr. 

 bellilineata, Billings, 1866, Catal. Sil. Foss. 



Antic, p. 15, Hud. Riv. Gr. 

 bisulcata, see Grammysia bisulcata. 

 brisa, Hall, 1867, 20th Rep. N. Y. Mus. 



Nat. Hist., p. 384, syn. for P. strisecosta. 

 cancellata, Barris, 1879, (Avicula cancel- 



lata,) Proc. Dav. Acad. Sci., vol. 2, p. 



286, Corniferous limestone. 



