356 



BRA CHIOPODA. 



[ORB. CRT. 



canadensis, see Dinobolus canadensis. 



conradi, see Dinobolus conradi. 



galtensis, see Tri- 

 merella galten- 

 sis. 



labradoricy.s, see 

 Kutorgina lab- 

 FIG. 589. Obolus apolli- radorica. 



nis. 6, Dorsal valve; (?) murrayi, Bill- 



a, interior of ventral j n gs 1865, Pal. 



valve Foss., vol. 1, p. 



362, Quebec Gr. or Up. Taconic. 



pectinoides, Whitfield, 1875, Ludlow'sRep. 

 Black Hills of Dakota, p. 103, Up. 

 Taconic. 



Orbicula, Cuvier, 1808, Tabe. Elem. d'Hist. [ 

 Nat,, p. 435, syn. for Crania. 



cselata, see Lingulella CH'lata. 



cancellata, see Trematis cancellata. 



corrugata, see Crania corrugata. 



crassa, see Obolella crassa. 



deformata, see Crania deformata. 



eccentrica, see Crania eccentrica. 



filosa, see Schizocrania filosa. 



grandis, see Discina grandis. 



Iamello8a,see Discina lamellosa. 



lodensis, see Discina lodensis. 



minuta, see Discina minuta. 



nitida, see Discina nitida. 



prima, see Crania prima. 



squamiformis, see Pholidops squamiformis. 



subtruncata, see Pholidops subtruncatus. 



tenuilamellata, see, Discina tenuilamellata. 



terminalis, see Trematis terminalis. 



truncata, see Crania truncata. 

 ORBICULOIDEA, D'Orbigny, 1847, Comptes 

 rendus de 1'Academie des Sciences, and 

 Prodr. de Paleont., t. 1, p. 44. [Ety. 

 Orbifula, a genus; aides, like.] Subor- 

 bicular, patelliform, longitudinally or 

 transversely oval, upper valve convex, 

 with vertex near the posterior margin ; 

 lower valve conical or concave ; no 

 pedicle disk ; a narrow oval or circular 

 aperture, more or less confined in its | 

 shape, is situated in a furrow or depres- 

 sion. Type O. elliptica. 



conica, Dwight, 1880, Am. Jour. Sci. and 

 Arts, 3d ser., vol. 19, p. 452, Tren- 

 ton Gr. 



ORTHIS, Dalman, 1827, Kongl. Vet. Acad. 

 Handl., p. 93. [Ety. orthos, straight, in 

 allusion to the straight hinge-line.] 

 Shell variable in form, hinge-line 

 straight; valves convex or plano-con- 

 vex, plicated, with or without mesial 

 fold and sinus ; cardinal area notched in 

 the center ; ventral valve with two 

 prominent diverging teeth, muscular 

 impression saucer-shaped, divided by a 

 median septum on which the central 

 adductor attached ; divaricator and ped- 

 icle impressions, lateral, fan-like ; dor- 

 sal valve with a tooth-like, cardinal 

 process between two curved brachial 

 processes; adductor impression quad- 

 ruple ; vascular impressions numerous, 

 spreading ; no coiled spiral arms. Type 

 O. zonata and O. callactis. 



aeuminata, Billings, 1859, Can. Nat. Geo., 



vol. 4, p. 440, Chazy Gr. 

 acutilirata, Conrad, 1842, (Delthyrisacuti- 



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



260, Hud. Riv. Gr. 

 acutiloba, Ringueberg, 1888, Proc. Acad. 



Nat. Sci. Phil., p. 134, Niagara Gr. 

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



p. 120, Trenton Gr. 



aequivalva, Shaler. The name was pre- 

 occupied. 



sequivalvis, Hall, see Orthis eryna. 

 alata, Shaler. The name was preoccupied, 

 alsus, Hall, 1863, 16th Rep. N. Y. St. 



Mus. Nat. Hist., p. 33, Schoharie grit, 

 alternans, Casteluau, 1843, Syst. Sil., p. 



38. Not recognized, 

 amcena, Winchell, 1880, Geo. Sur. Minn. 



8th Rep., p. 65, Hud. Riv. Gr. 

 anticostiensis, syn. for Orthis porcata. 

 apicalis, Billings, 1865, Pal. Foss., vol. 1, 



p. 301, Quebec Gr. 

 armanda, Billings, 1865, Pal. Foss., vol. 1, 



p. 303, Quebec Gr. 

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



175, Low. Held. Gr. 

 aurelia, Billings, 18*74, Pal. Foss., vol. 2, p. 



34, Gaspe limestone No. 8, Devonian. 

 barabuensis, see Lepta.'na barab'uensis. 

 battis, Billings, 1865, Pal. Foss., vol. 1, p. 



185, Quebec Gr. 

 bellarugosa, Conrad, 1843, Proc. Acad. 



Nat. Sci. Phil., vol. 1, p. 333, and Pal. 



N. Y., vol. 1, p. 118, Trenton Gr. 

 bellula, Meek, 1873, Ohio Pal., vol. 1, p. 



103, Hud. Riv. Gr. 

 biforata, Scblotheim, 1820, (Terebratulites 



biforatus,) Petrefact., p. 265, Trenton 



and Hud. Riv. Grs. 

 billingsi, Hartt, 1868, Acad. Geol., p. 644, 



St. John Gr. 

 biloba, Linna-us, 1767, (Anomia biloba,) 



Linne. Syst., ed. 12, p. 1154, Niag- 

 ara Gr. 

 bilobata, Conrad, 1838, (Delthyrisbilobata,) 



Ann. Rep. N. Y. The name was pre- 

 occupied by Sowerby. 

 bisulcata, see Camarella bisulcata. 

 borealis, Billings, 1859, Can. Nat. Geo., 



vol. 4, p. 436, Chazy and Trenton Grs. 

 carbonaria, Swallow, 1858, syn. for Orthis 



pecosi. 

 carinata, Hall, 1843, Geo. Rep. 4th Dist. 



N. Y., p. 267, and Pal. N. Y., vol. 4, p. 



58, Portage and Chemung Grs. 

 carleyi, Hall, syn. for Orthis retrorsa. 

 centrilineata, Hall, 1847, Pal. N. Y., vol. 



1, p. 289, Hud. Riv. Gr. 

 centrosa, n. sp., Hud. Riv. Gr. Proposed 



instead of O. crassa, in Cin. Quar. Jour. 



Sci., vol. 1, p. 20, and Ohio Pal., vol. 1, 



p. 117, pi. 10, fig. 3. 

 charlottae, Winchell, 1880, Geo. Sur. Minn., 



8th Rep., p. 67, Hud. Riv. Gr. 

 cincinnatiensis, S. A. Miller, 1883, 2d *Ed. 



Am. Pal. Foss., p. 296, Hud. Riv. Gr., 



Cincinnati, Ohio. Proposed instead of 



Orthis costata, Hall, 1845, Am. Jour. 



Sci. and Arts, vol. 48, p. 294. 



