US. MAR.] 



PISCES. 



601 



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

 Sur. 111., vol. 6, p. 363. [Ety. lisgos, a 

 spade ; odous, tooth.] Teeth laterally 



FIG. 1142. Liognatlms spatulatus. 



abbreviated strong ; crown thick, sharp- 

 crested, and sometimes obscurely ser- 

 rated ; ba^al margins well defined ; base 



p. 302. [Ety. mochaira, a saber; akan- 

 tha, a spine.] Spines large, flattened, 

 curved, ancipital, unsymmetrical; edges 

 and point acute; base narrowed, with a 

 rough and irregular extremity; central 

 cavity reaching nearly to the apex ; ex- 

 ternal surface enameled, smooth or 

 punctate, and striate microscopic struc- 

 ture dense. Type M. major. 



major Newberry, 1857, Bull. Nat. Inst., 

 p. 6, and Ohio Pal., vol. 1, p. 304, Up. 

 Held. Gr. 



peracutus, Newberry, 1857, Bull. Nat. 

 Inst., p. 6, and Ohio Pal., vol. 1, p. 305, 

 Up. Held Gr. 



FIG. 1145. Machseracanthus peracutus. 



vertical to the crown, rectangular, 

 prolonged, equal to the elevation of the 

 crown; inferior nirface well denned 

 from either face above ; and generally 

 slightly beveled from the concave to the 

 opposite border ; coronal surface en- 

 ameled, worn crest striato-punctate. 

 Type L. curtus. 



curtus, St. John & Wor- 

 then, 1875, Geo. Sur. 111., 

 vol. 6, p. 364, Burlington 

 Gr. 



selluliformis, St. John & 

 FIG. 1143. - Us- Worthen, 1875, Geo. Sur. 

 godus curtus. m^ vo }. 5, p. 366, St. 



Louis Gr. 



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

 Sur. 111., vol. 6, p. 365, Burlington Gr. 

 LISTRACANTHUS, Newberry & Worthen, 1870, 

 Geo. Sur. 111., vol. 4, p. 371. [Ety. fts- 

 tron, shovel ; akanlha, spine.] Spines 

 small, gently arched, flattened, thin ; 

 sides marked by numerous sharp, lon- 

 gitudinal carinae, edges set with diver- 

 gent, slender, acute teeth ; most numer- 

 ous on the convex margin; and largest 

 base expanded and obliquely truncated. 

 Type L. hystrix. 

 hildrethi,New- 

 berry, 1875, 

 Ohio Pal., 

 vol. 2, p. 56, 

 Coal Meas. 

 hvstrix New FlG - l144 - ~~ Listracanthus 

 berry &Wor- hystrix " 



then, 1870, Geo. Sur. 111., vol. 4, p. 372, 

 Coal Meas. 



Loplwdus, Newberry '& Worthen, 1870, Geo. 

 Sur. 111., vol. 4. This name was preoc- 

 cupied by Romanowsky in 1864. 

 variabilis, see Agassizodus variabilis. 

 MACH*:RACANTHUS, Newberry, 1857, Bull. 

 Nat. Inst., p. 6, and Ohio Pal., vol. 1, 



sulcatus, Newberry, 1867, Bull. Nat. Inst, 

 p. 6, and Ohio Pal., vol. 1, p. 305, Up. 

 Held. Gr. 



M A C R O P E TALICHTHYS, 



Norwood & Owen, 

 1846, Am. Jour. Sci., 

 2d ser., vol. 1, p. / 

 367. [Ety. makros, 

 large ; petalos, ex- 

 panded or spread 

 out; ichthys, fish.] 

 Cranium composed 

 of large polygonal 

 plates, united by 

 double sutures ; sur- FIG- H46.-Macropet- 

 fflpp pnnmplpH tn alichthys sulli- 

 tace enameled , tu- v a n t j O ne^flf th 

 bercled, ornament- natural size, 

 ed ; eye orbits con- 

 spicuous ; nasal plate wedge-shaped ; 

 occipital plate oblong, emarginate be- 

 hind, and prolonged anteriorly, where 

 it meets the nasal plate. Type M. 

 rapheidolabis. 



manni, Newberry, (Agassichthys manni,) 

 1857, Bull. Nat. Inst., p. 3, Up. Held. Gr. 



rapheidolabis, Norwood & Owen, 1846, 

 Am. Jour. Sci., 2d ser., vol. 1, p. 367, 

 Up. Held. Gr. 



sullivanti, Newberry, 1857, (Agassichthys 

 sullivan ti,) Bull. Nat. Inst., p. 3, and 

 Ohio Pal., vol. 1, p. 294, Up. Held. Gr. 

 MARRACANTIUIS, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 465. [Ety. mar- 

 ron, a spade; akantha, spine.] Dorsal 

 spine nearly straight, or with a forward 

 curvature, obtusely terminated, rounded 

 in front, truncated behind, or rounded 

 into the posterior face, which is longi- 

 tudinally ridged in apparent continu- 

 ity with the lateral costae; lateral face 

 and anterior margin longitudinally 

 ridged, the costse being tuberculated, 

 those in front more or less strongly 



