HEL. HOL.] 



PISCES. 



599 



hook; odous, tooth.] Teeth laterally 

 elongated, vertically arched, gently 

 curved outward in the concave face ; 

 margins nearly parallel; crown com- 

 pressed along the crest; serrated, ex- 

 panded below; convex face low, op- 

 posite face concave ; coronal borders 

 produced inbeveled ; base strong, ob- 

 liquely produced ; lateral angles well 

 defined. Type H. dentatus, or, more 

 properly, H. occidentalis. 



compactus, St. John & 

 Worthen. 1875, Geo. 

 Sur. 111., 'vol. 6, p. 355, 

 Kaskaskia Gr. 

 occidentalis, St. John & 

 Worthen, 1875, Geo. 

 Sur. 111., vol. 6, p. 355, 

 St. Louis Gr. 

 HELIODUS, Newberry, 1875, Ohio Pal., vol. 

 2, p. 62. [Ety. helios, sun ; odous, tooth.] 

 Distinguished from Dipterus by having 

 the upper palate teeth united, forming a 

 rounded, semicircular, triturating plate, 

 bearing radiating tuberculated ridges. 

 Type H. lesleyi. Dr. Traquair, of Eng- 

 land, regards Heliodus as a synonym 

 for Palaedaphus, Van Beneden & De- 

 Koninck, 1864, Bull. Acad. Belg., vol. 

 17, p. 143. 



Flo. 1135. Harpa- 

 codus occiden- 

 talis. 



FIG. 1136. -Heliodus lesleyi. 



lesleyi, Newberry, 1875, Ohio Pal., vol. 2, 



p. 64, Chemung Gr. 



HELODUS, Agassiz, 1843, Recherches sur les 

 Poissons Fpssiles, t? 3, p. 104. [Ety. 

 helos, a nail or rudder ; odous, tooth.] 

 Transversely elongate, crown convex, 

 elevated along the middle into an ob- 

 tuse, circular ridge, sometimes divided 

 into a line of several compressed cones 

 diminishing from the center; surface 

 porous as in Psammodus ; margin of the 

 crown raised in the middle on both the 

 inner and outer sides, and it and the 

 root vertically plicated. Type H. 

 simplex. 



angulatus, Newberry & "Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 83, Burlington Gr. 



biformis, Newberry & Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 77, Waverly or 

 Kinderhook Gr. 



carbonarius, Newberry & Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 75, Coal Meas. 



compressus, Newberry & Worthen, 1870, 



Geo. Sur. 111., vol. 4, p. 360, Burlington Gr. 



compressus, see Hybocladodus compressus. 



coniculus, Newberry & Worthen, 1866, 



Geo. Sur. 111., vol. 2. p. 75, Burlington Gr. 



consolidate. Newberry & Worthen, 1866, 



Geo. Sur! 111., vol. 2, syn. for Chitono- 



dus latus. 



crenulatus, Newberry & Worthen, 1866, 



Geo. Sur. 111., vol. 2, p. 82, Keokuk Gr. 



denshumani, Newberry & Worthen, 1866, 



Geo. Sur. 111., vol. 2, p. 76, Keokuk Gr. 



denticulatus, Newberry & Worthen, 1866, 



Geo. Sur. 111., vol. 2, p. 81, Keokuk Gr. 



elytra, Newberry & Worthen, 1866, Geo. 



Sur. 111., vol. 2, p. 78, Keokuk Gr. 

 gibbosus, Newberry 

 & Worthen, 1866, 

 Geo. Sur. 111., vol. 

 2, p. 79, Keokuk 

 Gr. 



gibbus, Leidy, 1856, 

 Trans. Am. Phil. 

 Soc., vol. 11, p. 87, FIG- 1137. Helodus gib- 

 Keokuk Gr. bosus - 



limax, Newberry & Worthen, 1866, Geo. 



Sur. 111., vol. 2, p. 80, Burlington Gr. 

 nobilis, Newberry & Worthen, 1866, Geo. 

 Sur. 111., vol. 2, same as Chitonodus 

 latus. 



placenta, see Psephodus placenta, 

 politus, Newberry & Worthen, 1866, Geo. 



Sur. 111., vol. 2, p. 79, Keokuk Gr. 

 rugosus, Newberry & Worthen, 1866, Geo. 



ur. 111., vol. 4, p. 359, Coal Meas. 

 sulcatus, Newberry & Worthen, 1866, 

 Geo. Sur. 111., vol. 2, p. 82, Keokuk Gr. 

 undulatus, Newberry & Worthen, 1866, 

 Geo. Sur., 111., vol. 2, p. 82, Keokuk Gr. 

 HOLOPTYCHIUS, Agassiz, 1836, Recherches 

 sur les Poissons Fossiles, t. 2, p. 179. 

 [Ety. holos, entire ; ptyx, wrinkle.] Body 

 thick, short, rounded, bones of the 

 head granulated; scales large, very 

 thick, subrhomboidal, rounded, imbri- 

 cating, composed of numerous bony 

 layers, exposed surface marked with 

 large, longitudinal, flexuous wrinkles 

 and tubercles ; teeth small, numerous, 

 conical, longitudinally sulcated at base; 

 tail heterocercal, caudal fin triangular, 

 obliquely truncated ; dorsal fin oppo- 

 site a similar anal one close to the base 

 of the caudal; ventral 

 behind the middle of 

 the body. Type H. 

 giganteus. 



americanus, Leidy, 1856, 

 Jour. Acad. Nat. Sci., 2d 

 series, vol. 3, p. 159, 

 Catskill Gr. 



nobilisshnus, Agassiz, as 

 identified by Hall, 1843, . 

 Geo. Rep. 4th Dist. N.Y., 

 is described as H. ameri- 

 canus. 



taylori, Hall, 1843, (Sauripteris taylori,) 

 Geo. Rep. 4th Dist. N. Y., p. 282, Cats- 

 kill Gr. 



FIG. 1138-Holop- 

 tychlus ameri- 

 canus. Single 

 tooth. 



