AND AVES OF NORTH AMERICA. 25 



LAB-Y-RIKTTHODOlSrTIA.* 



DICTYOCEPHALUS, Leidy. 



DICTYOCEPHALUS ELEGANS, Leidy. 



Proo. Ac. Nat. Sci., 1856, 256, Emmons' Geology Nor. Amer. p 59. Tab. 

 Triassic Coal Beds, Chatham County, North Carolina. 



BAPHETES, Owen. 



BAPHETES PLANICEPS, Owen. 



Quart. Journ. Geol. Soe. Loud., X., 1853, Tab. (XI notes.) 

 Carboniferous Coal Measures of the Jog-gins, Nova Scotia. 



ETTPELOR, Cope. 



ETJPELOR DURJIS, Cope. 



Mastodonsaurus durus, Cope. Proc. Acad. Nat. Sci. Philadelphia, 1866. 249. 



A portion of the table of the cranium of a large labyrinthodont accompanied other fragments of the same in a bed 

 of hard black shale, according to Wheatley's section of the Trias at Phcenixville, 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 3j 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 anterior 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 Labyrinthodonts. 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 Phcenixville, Chester County, Penna. Discovered by Charles 51. 

 Wheatley. 



Teeth subcylindric, with large pulp cavity at the basis only : external surface without grooves ; dentine divided 

 by numerous flat vertical laminae of a dense 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 (I. 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 jaegeri 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 Labyrinthodonts, 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 sulcatas Lea which I referred here in my synopsis of Extinct Batrachia, Proceed. Acad. Nat. Sci., 186$, 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. PHILOSO. SOC VOL. XIV. T 



