ORA. — ORO.] 



PISCES. 



603 



gle ; dentary bones posteriorly acute, 

 where they are overlapped by the artic- 

 ular portions of the mandibles, long 

 and narrow, curving upward to the 



Fig. 1149.— Mycterops ordinata. 



symphysis, where they support an in- 



ter-mandibular arch of bone, to which 

 is attached a series 

 of large, curved, con- 

 ical teeth ; body cov- 

 ered with imbricated 

 circular scales. Type 

 O. sigmoides. 

 hopkinsi, Newberry, 

 1857, Bull. Nat. Inst., 

 p. 5, Chemung Gr. 

 sigmoides, Newberry, 

 1857, Bull. Nat. Inst., 



p. 5, and Ohio Pal., vol. 1, p. 299, Up. 



Held. Gr. 



Fig. 1150.— Onycho- 

 dus s i g m oides. 

 One-hall nat. size 

 of inter-mandib- 

 ular crest with 6 

 teeth . 



Fig. 1151.— Onychodus sigmoides. Fragment of 

 the right mandible. 



Obacanthus, Agassiz, 1843, Eecherches sur. 

 les Poissons Fossiles, t. 3, p. 13. LEty. 

 oraios, beautiful ; akantha, spine.] Dor- 

 sal rays large, conical, without solid 

 base, hollow, walls thin, surface tuber- 

 culated ; no posterior rows of denticles. 

 Type O. milleri. 



abbreviatus, Newberry, 1857, Bull. Nat. 

 Inst., p. 5, Up. Held. Gr. 



consimilis, St. John & Worthen, 1875, Geo. 

 Sur. 111., vol. 6, syn. for O. vetustus. 



fragilis, Newberry, 1857. Bull. Nat. Inst., 

 p. 5, Up. Held. Gr. 



granulatus, Newberry, 1857, Bull. Nat. 



Inst., p. 5, Up. Held. Gr. 

 multiseriatus, Newberry, 1857, Bull. Nat. 

 Inst., p. 5, Up. Held. Gr. 

 (?) obliquus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 477, Keo- 

 kuk Gr. 

 pnigeus. This species is made the type 

 of the genus Pnigeacanthus. See P. 

 deltoides. 

 rectus, St. John & Worthen, 1883, Geo. 

 Sur. 111., vol. 7, p. 257, Kaskaskia Gr. 

 vetustus, Leidy, 1856, Jour. Acad. Nat. 

 Sci. Phil., 2d ser., vol. 3, p. 162, St. 

 Louis Gr. 

 Orodus, Agassiz, 1843, Recherchfs sur les 

 Poissons Fossiles, t. 3, p. 97. [Ety. 

 oraios, beautiful; odous, tooth.] Teeth 

 laterally elongated, middle more ele- 

 vated than extremities, forming an 

 obtuse transverse cone; longitudinal 

 diameter greatest and marked by a 

 medial ridge with oblique secondary 

 ridges. Type O. cinctus. 

 alleni, St. John & Worthen, 1875, Geo. 



Sur. 111., vol. 6, p. 310, Coal Meas. 

 carinatus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 307, Keokuk Gr. 

 corrugaius, see Agassizodus corrugatus. 

 dsedaleus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 301, Waverly 

 or Kinderhook Gr. 

 decussatus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 300, Waverly or 

 Kinderhook Gr. 

 elegantulus, Newberry & Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 64, Burling- 

 ton Gr. 

 fastigiatus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 306, Burling- 

 ton Gr. 

 major, St. John & Worthen, 1875, Geo. 

 Sur. 111., vol. 6, p. 302, Burlington Gr. 

 mammillaris, Newberry 

 & Worthen, 1866, Geo. 

 Sur. 111., vol. 2, p. 66, 

 Keokuk Gr. 

 minusculus, see Desmio- FlG }j52_orodus 



dus minusculus. mammillaris. 



minutus, Newberry & 

 Worthen, 1866, Geo. Sur. 111., -vol. 2, p. 

 68, Keokuk Gr. 

 multicarinatus, Newberry & Worthen, 

 1866, Geo. Sur. 111., vol. 2, p. 62, Wa- 

 verly or Kinderhook Gr. 

 neglectus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 308, St. Louis Gr. 

 ornatus, Newberry & Worthen, 1866, Geo. 



Sur. 111., vol. 2, p. 65, Keokuk Gr. 

 parallelus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 295, Waverly or 

 Kinderhook Gr. 

 parvulus, St. John & Worthen, 1875, Geo. 



Sur. 111., vol. 6, p. 309, St, Louis Gr. 

 plicatus, Newberry & Worthen, 1866, Geo. 



Sur. 111., vol. 2, p. 63, St. Louis Gr. 

 tuberculatus, Newberry & Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 66, Burling- 

 ton Gr. 



