Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/29

 AND AYES OF NORTH AMERICA. DICTYOCEPHALUS, Leidy. DICTYOCEPHALUS ELEGANS, Leidy. Proc. Ac. Nat. Sci., 1856, 256, Emmons' Geology Nor. Amer. p 50. Tab. Triassic Coal Beds, Chatham County, North Carolina. BAPHETES, Owen. BAPHETES PLANICEPS, Owen. Quart. Journ. Geol. Soc. Loud., X., 1853, Tab. (XI notes.) Carboniferous Coal Measures of the joggins, Nova Scotia. EUPELOR, Cope. EUPELOR DURO, Cope. ..Vastodonsautus durus, Cope. Proc. Acad. Nat. Sci. Philadelphia, 1866. 2.19. A portion of the table of the cranium of a large labyrinthodont accompanied other fragments of the same iu a bed of hard black shale, according to Wheatley's section of the Trias at Phoenixville, Pa., (in Silliman's Journal Sci. Arts, 1861, 45.) about 181 feet from the top of the series, while a tooth formerly described with it is from near _83 feet higher, in "the Plant bed." The Belodon comes from the same as the last. The largest fragment is eight inches long and eight and one-half wide, and is a portion of the table of the cranium exhibiting the usual medial depression and embracing portions of the postorbital and parietal bones ; one of the former is four inches six lines long ; both are pitted medially (about 31 pits in an inch) and marked with short coarse sulci posteriorly. The parietals are two inches nine lines wide behind, and four inches wide between the autetior parts of the postorbitals. On what is probably the posterior part of the interorbital region (a small part of the posterior margin of the left orbit is preserved) commence two smooth, shallow sulci 1 in. 2 1. apart, which are probably the posterior extremities of the superficial channels of the face of the Labyriuthodonts. Between them the surface is pitted (four or five to the inch). The parietal bones are throughout longitudinally sulcate (four and one-half to the inch), with obtuse ridges between. The parietal fontanelle was not discoverable, nor could the form of the orbits be certainly determined, though they were probably not large. From the Triassic Red Sandstone near Phoenixville, Chester County, Penna. Discovered by Charles N. Wheatley. Teeth subcyliudric, with large pulp cavity at the basis only : external surface without grooves ; dentine divided by numerous fiat vertical lamime of a deuse substance, probably enamel, which radiate from very near the pulp cavity to the external enamel layer. I have been much puzzled with the teeth which I described (/. c.) in the above language, as typical of this genus. Their constitution has been chemically altered, and the section exhibits the radii of a denser material which unites at right angles with a sheath of the same substance which envelopes the tooth externally. The teeth are of various sizes, sometimes two inches long and more slender in proportion to the length than those of the Mastodonsaurus jsegeri and salamandroides ; they are cylindrical, gently curved and acuminate without external sulci : of the minute sculpture little can be said, but the casts of the surface are smooth. The roots exhibit a short conic pulp cavity. In a few weathered sections the denser radii are well displayed. They are not convolute as in Labyrinthoclonts, but perfectly straight and convergent to a minute central vacuity. In a tooth four lines in diameter there appear to be five principal radii, which though exceedingly delicate may some-times be seen in longitudinally fractured specimens.
 * The Centemodon suleatue Lea which I referred here In my synopsis of Extinct Batrachla, Proceed. Acad. Xat. Scl..1868, may be placed among the Thecodonts. I was Induced to place it here by Lea's ascription of sulci and pulp cavity to the tooth, which I did not understand properly. AMERI. PHILOS°. SOC.—VOL. XIV. 7