610 



PISCES. 



[PSE. PTY. 



semicylindricus, Newberry & Worthen, 

 1866, Geo. Sur. 111., vol. 2, p. 109, syn. 

 for Sandalodus Isevissimus. 



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

 Sur. 111., vol. 7, p. 202, Upper Burling- 

 ton Gr. 



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

 Sur. 111., vol. 7, p. "205, Up. Burling- 

 ton Gr. 



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



Sur. 111., vol. 7, p. 206, Keokuk Gr. 

 PSEPHODUS, Agassiz, 1862, Quar. Jour. Geo. 

 Soc., vol. ;18, p. 102. [Ety. psephos, a peb- 

 ble ; odous, a tooth.] Heavy, more or less 

 spirally inrolled triturating or crushing 

 plates invest the median range of the 

 rami of the jaws; they are trapezoidal 

 in outline, with undulated articular 

 surfaces. Type P. magnus. 



convolutus, Newberry & Worthen, 1866, 

 (Aspidodus convolutus,) Geo. Sur. 111., 

 vol. 2, p. 94, Kaskaskia Gr. 



crenulatus, Newberry & Worthen, 1866, 

 (Aspidodus crenulatus,) Geo. .Sur. 111., 

 vol. 2, p. 93, Kaskaskia Gr. 



cunulalus, see P. lunulatus. 



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

 Sur. 111., vol. 7, p. 72, St. Louis Gr. 



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

 Sur. 111., vol. 7, p. 74, (misprinted 

 cunulatus,) Kaskaskia Gr. 



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

 Sur. 111., vol. 7, p. 66. Waverly or Kin- 

 derkook Gr. 



placenta, Newberry & Worthen, 1866, 

 (Helodus placenta,) Geo. Sur. 111., 

 vol. 2, p. 80, Waverly or Kinder- 

 kook Gr. 



reticulatus, St. John & Worthen, 1875, 

 Geo. Sur. 111., vol. 6, p. 417, Waverly or 

 Kinderhook Gr. 



symmetricus, St. John & Worthen, 1883, 

 Geo. Sur. 111., vol. 7, p. 71, Waverly or 

 Kinderhook Gr. 



PTERICIITHYS, Agassiz, 1835, Recherches sur 

 les Poissons Fosgiles, t. 1, p. 302. [Ety. 

 pteron, fin ; ichthys, fish.] The outline 

 of this genus reminded Hugh Miller of 

 the figure of a man rudely drawn in 

 black on a gray ground, the head cut 

 off at the shoulder?, the arms spread 

 at full as in the attitude of swimming, 

 the body rather long than otherwise, and 

 narrowing from the chest downward, 

 one of the legs cut away at the hip-joint, 

 and the other as if to preserve the bal- 

 ance, placed directly under the center 

 of the figure, which it seems to support. 

 The under part of the body was flat, 

 the upper rose toward the center 

 into a roof-like, ridge, and both under 

 and upper were covered with a strong 

 armor of plates ; the plates.on the under 

 side are divided by a longitudinal 

 suture and a transverse suture, and 

 they would cut at right angles were it 

 not for a lozenge-shaped plate in the 

 center; there are therefore five plates 

 on the under side, all of which are 



thickly tuberculated ; the upper side'is 

 covered with a large, long, hexagonal 

 plate in the central part, that is sur- 

 rounded by a row of unequal and vari- 

 ously formed plates, all of which are 

 strongly tuberculated; the cephalic 

 shield is rounded in front, andtruncated 

 behind where it joins the body cara- 

 pace, having a transverse median open- 

 ing; nuchal region occupied by a plate 

 somewhat like the lateral view of a 



FIG. 1169. Ptericbthys millerl. 



coronet or crown; one post-median 

 plate, another in front, one lateral 

 occipital on each side, two lateral 

 and one postero- lateral on each side, 

 and an angular plate on each postero- 

 lateral side articulating with the 

 limb; the oblong carapace is cov- 

 ered by the large, hexagonal antero- 

 median plate, and a smaller posterior 

 median dorsal, and two dorso-lateral 

 plates on each side ; tail thick, conical, 

 covered with rhomboidal scales; surface 

 covered with granules. Type P. mil- 

 leri. 



canadensis, see Bothriolepis canadensis. 



norwoodensis, Owen, syn. for Macropetal- 

 ichthys rapheidolabis. 



rugosus, Claypole, 1883, Proc. Am. Phil. 



Soc., p. 664, Upper Chemung Gr. 

 PTYCTODUS, Pander Uber die Ctenodipteri- 

 nen des Devonischens Systems, p. 48. 

 [Ety. ptyktos, folded; odous, tooth.] 

 Elongated ; base expanded, subconical ; 

 crown flattened or furrowed ; enameled ; 

 tubes in transverse furrows, with 

 low intervening ridges. Type P. 

 obliquus. 



calceolus, Newberry & Worthen, 1866, 

 (Rinodus calceolus,) Geo. Sur. 111., vol. 

 2, p. 106, Ham. Gr. 



PTYONODUS, Cope, 1877, Proc. 'Am. Phil. 

 Soc., p. 192. [Ety. ptyon, a fan ; odous, 

 a tooth.] 



paucicristatus, Cope, 1877, Proc. Am. 

 Phil. Soc., p. 54, Permian. 



vinslovi, Cope, 1877, Proc. Acad. Nat. 

 Sci. Phil., p. 410, Permian. 



