PI.E.] 



LAMELLIBRANCHIA TA. 



503 



Species are left here for want of ma- 

 terial to determine their generic rela- 

 tions. 



carbonaria, Meek & 



Worthen, 18 66, 



Proc. Chi. Acad. 



Sci., vol. 1, p. 13, 



Up. Coal Meas. 



recticardinalis,Meek, 



1875, Ohio Pal., 



vol. 2, p. 331, Coal 



Meas. 



Fig. 894.— Placuuopsis Plethomytilus, Hall, 



1883, Pal. N. Y., 



vol. 5, pt. 1, p. 4. 



(Plates and Ex- 



pletho, to be full ; 



Mytiloid, gibbous; 



recticardinalis. "In- 

 ternal cast of left 

 valve. 



planations.) (Ety. 

 Mylilus, a genus.] 



ligamental area finely striated ; no car- 

 dinal teeth ; lateral teeth small, oblique; 

 test, with concentric striae ; differs from 

 Mytilacra in its true hinge-line and the 

 absence of teeth. Type P. ponderosus. 



Pig. 895.— Plethomytilus ponderosus. 



arenaceus, Hall, 1870, (Mytilarca arena- 



cea,) Prelim. Notice Lam. Shells, p. 



20, and Pal. N. Y., vol. 5, pt. 1, p. 253, 



Schoharie grit, 

 knappi, Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. 256, Ham. Gr. 

 mytilimeris, Conrad, 1842, (Inoceramus 



mytilimeris,) Jour. Acad. Nat. Sci., 



vol. 8, p. 246, Low. Held. Gr. 



oviformis, Conrad, 1842, (Inoceramus 

 oviformis,) Jour. Acad. Nat. Sci., vol. 

 8, p. 246, and Pal. N. Y., vol. 5, pt. 1, 

 p. 255, Ham. Gr. 



ponderosus, Hall, 1870, (Mytilarca pon- 

 derosa,) Prelim. Notice Lam. Shells, p. 

 21, and Pal. N. Y., vol. 5, pt. 1, p. 254, 

 Up. Held. Gr. 

 Pleurophorus, King, 1844, Ann. Mag. Nat. 

 Hist., vol. 14, p. 313. [Ety. pleuron, a 

 rib; phoros, bearing.] Inequilateral, 

 longitudinally o"blong or subovate ; two 

 cardinal teeth in each valve, alternately 

 interlocking and divergent; one pos- 

 terior lateral tooth in each valve, the 

 receiving tooth in the left valve; an- 

 terior adductor scar deep, and bounded 

 posteriorly by a ridge ; pallial line sim- 

 ple. Type P. costatus. 



angulatus, Meek & Worthen, 1865, Proc. 

 Acad. Nat. Sci. Phil., p. 247, and Geo. 

 Sur. 111., vol. 6, p. 529, Coal Meas. 



calhouni, Meek & Hayden, 1858, (Ed- 

 monia calhouni,) Trans. Alb. Inst., vol. 

 4, p. 80, and Pal. Up. Mo., p. 62, Per- 

 mian Gr. 



chesterensis, Worthen, 1884, Bull. No. 2, 

 111. St. Mus. Nat. Hist., p. 16, and Geo. 

 Sur. 111., vol. 8, p. 123, Kaskaskia Gr. 



costatiformis, Meek & Worthen, 1865, 

 Proc. Acad. Nat. Sci. Phil., p. 247, and 

 Geo. Sur. 111., vol. 3, p. 535, Keokuk Gr. 



meeki, Walcott, 1885, Monogr. U. S. Geo. 

 Sur., vol. 8, p. 246, Carboniferous. 



minimus, Worthen, 1884, Bull. No. 2, 111. 

 St. Mus. Nat. Hist, p. 17, and Geo. Sur. 

 111., vol. 8, p. 124, St. Louis Gr. 



monroensis, Worthen, 1884, Bull. No. 2, 

 111. St. Mus. Nat. Hist., p. 17, and Geo. 

 Sur. 111., vol. 8, p. 125, St. Louis Gr. 



oblongus, Meek, 1872, Pal. E. Neb., p. 212, 

 Coal Meas. 



occidentalis, Meek & Hayden, 1862, Trans. 

 Alb. Inst., vol. 4, p. 80, and Pal. Up. 

 Mo., p. 35, Coal Meas. 



pallasi, as identified by Geinitz, is P. 

 oblongus. 



permianus, Swallow, 

 1858, Trans. St. 

 Louis Acad. Sci., 

 vol. 1, p. 192, Per- 

 mian Gr. 



quadricostatus, Daw- 

 son, 1868, Acad 

 Geo., p. 304, Car 

 boniferous. 



8implw, as identified by Geinitz, is P. 

 subcuneatus. 



subcostatus, Meek & Worthen, 1865, Proc. 

 Acad. Nat, Sci. Phil., p. 246, and Geo. 

 Sur. 111., vol. 2, p. 347, Up. Coal Meas. 



subcuneatus, Meek & Hayden, 1858, 

 Trans. Alb. Inst., vol. 4, p. 81, and Pal. 

 Up. Mo., p. 61, Permian Gr. 



(?) subellipticus, Meek, 1867, Am. Jour. 

 Sci., vol. 44, p. 181, and Pal. E. Neb., 

 p. 211, Coal Meas. 



tropidophorus, Meek, 1875, Ohio Pal., vol. 

 2, p. 338, Coal Meas. 



Fig. 



. — Pleurophorus 

 costatiformis. 



