MEG. MOD.] 



LAMELLIBRANCHIA 7 A. 



489 



oblonga, Hall, 1859, Pal. N. Y., vol. 3, p. 

 277, Low. Held. Gr. 



obscura, Hall, 1859, Pal. N. Y., vol. 3. p. 

 277, Low. Held. Gr. 



occidualis, Walcott, 1885, Monogr. TJ. S. 

 Geo. Sur., vol. 8, p. 173, Devonian. 



ovata, Hall, syn. for Plethomytilus myti- 

 limeris. 



ovoidea, Hall, syn. for Plethomytilus my- 

 tiliraeris. 



rhomboidea, Hall, 1859, Pal. N. Y., vol. 3, 

 p. 275, Low. Held. Gr. 



spiuneri, Hall, 1859, Pal. N. Y., vol. 3, p. 

 274, Low. Held. Gr. . 



striata, Hall, 1860, Can. Nat. and Geo., vol. 

 5, p. 153, Up. Silurian. 



subcardiformis, Hall, syn. for M. cardii- 

 formis. 



suborbicularis, Hall, 1859, Pal. N. Y., vol. 



3, p. 273, Low. Held. Gr. 

 Megaptera, Meek & Worthen, 1866. The 



name was preoccupied. 

 Microdon, Conrad, 1842, Jour. Acad. Nat. Sci., 

 vol. 8. p. 247. This name was applied 

 by Agassiz to a genus of fish in 1833, 

 and was also preoccupied for a genus of 

 insects. Hall proposed Eodon, in 1877, 

 but Whitfield has shown that M. belli- 

 striatus is a Cypricardella, and hence the 

 latter name has priority. 



bellistriatus, see Cypricardella bellistriata. 



complanatus, see Cypricardella complanata. 



gregarius, see Cypricardella gregaria. 



reservatus, see Cypricardella reservata. 



tenuistriatus, see Cvricardella tenuistriata. 

 MODIELLA, Hall, 1884, 

 Pal. N. Y., vol. 5, p. 

 4. (Plates and Ex- 

 planations.) [Ety. 

 modus, a measure ; 

 ellus, diminutive.] 

 Subrhomboidal, nar- 

 rowed and auriculate 

 in front, broadly ex- 

 panding posteriorly; two well-marked 

 muscular impressions connected by a 

 simple pallial line ; surface with radi- 

 ating strise. Tppe M. pygmsea. 



P5'gmiea, Conrad, 1842, (Pterinea pyg- 

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

 251, and Pal. N. Y., vol. 5, pi. 76, figs. 

 9-20, Ham. Gr. 



Modiola, Lamarck, 1801, Syst. An. sans Vert. 

 [Eto. modiolus, a small measure or drink- 

 ing vessel.] Oblong, inflated in front, 

 umbones anterior, obtuse, no teeth; 

 pedal impressions three, the central 

 one elongated. Type M. modiolus. 

 Not a Palaeozoic genus. Species are 

 only left here for want of material to 

 properly determine the generic relations. 



avonia, Dawson, 1868, Acad. Geol.,p. 301, 

 Subcarboniferous. 



concentrica, see Modiomorpha concentrica. 



illinoisensis, Worthen, 1884, Bull. No. 2, 

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

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



lingualis, see Lithophaga lingualis. 



metella, see Mytilops metella. 



FIG. 849. Modiella 

 pygmeea. 



minor, Lea, 1852, Jour. Acad. Nat. Sci., 2d 

 series, vol. 2, Coal Meas. Not deter- 

 minable. 



FIG. 850. Modiola modiolus. aa, Anterior ad- 

 ductors ; a'a', posterior adductors ; uu.p'pf, pedal 

 muscles ; pp, byssal muscles ; /, foot ; 6, byssus ; 

 m, pallial Ime. 



nevadensis, Walcott, 1885, Monogr. TJ. S. 

 Geo. Sur., vol. 8, p. 239, Subcarbonif- 

 erous. 



obtusa, see Modiolopsis obtusa. 



pooli, Dawson, 1868, Acad. Geol., p. 301, 

 Low. Garb. Founded upon a small cast 

 destitute of characters. 



prsecedens, see Mytilops prsecedens. 



wyomingensis, Lea, 1852, Jour. Acad. Nat. 

 'Sci., 2d series, vol. 2, p. 205, Coal Meas. 

 Not recognized, but probably an An- 

 thracomya. 



MODIOLOPSIS, Hall, 1847, Pal. N. Y., vol. 1, 

 p. 157. [Ety. Modiola, a genus of shells ; 

 opsis, appearance; from its resemblance 

 to Modiola.] Equivalve, inequilateral, 

 elongated, broader posteriorly; um- 

 bones anterior; cardinal teeth short, 

 oblique; single, deep, subcircular ante- 

 rior muscular impression ; ligament ex- 

 ternal ; no area ; surface concentrically 

 lined. Type M. modiolaris. 



adrastia, Billings, 1862, Pal. Foss., vol. 1, 

 p. 45, Black Riv. Gr. 



anodontoides, Conrad, 1847, (Cypricardites 

 anodontoides,) Pal. N. Y., vol. 1, syn. 

 for M. sinuata. 



arcuata, Hall, 1847, Pal. N. Y., vol. 1, p. 

 159, Trenton Gr. 



aviculoides, Hall, 1847, Pal. N. Y., vol. 1, 

 p. 161, Trenton Gr. 



cancellata, AValcott, 1879, Trans. Alb. 

 Inst., vol. 10, p. 22, Utica Slate Gr. 



capax, n. sp. Shell very large, oblong ; 

 cardinal and basal lines behind the 

 beaks subparallel ; basal margin slightly 

 contracted by an undefined cincture 

 arising below the beaks; posterior end 

 broadly rounded; depressed in front of 



