NATURAL SCIENCES OF PHILADELPHIA. 211 



we cannot assert that they differ from the latter. The long spatuliform ele- 

 ments figured as pelvic are, perhaps, scapula?, which are of not very different 

 type in the Trachystomata, Proteida, and the Ganocephala. 

 " The only species included in this tribe in which inflections of the enamel 

 have been described, is the Dendrerpeton acadianum, and here it is only 

 at the base. It is, however, not impossible that this genus should not be asso- 

 ciated with Hylerpeton, Oestocephalus, etc. The genera Urocordylus, Cera- 

 terpeton, Lepterpetou, Ophiderpeton and others recently described by Prof. 

 Huxley, also belong here. 



PELIOX Wyman. 



In litteris. Raniceps Wyman, Amer. Jour. Sci. Arts, 1858, 158. Not of Cuvier 

 (Pediculati). 



Pklion lyelhi Wyman. Raniceps lyellii Wyman, 1. c. 



This animal differs from the genus Amphihamus in the well-ossified verte- 

 bral axis ; no remains of a tail with elevated neural spines exist in the type 

 specimen, and no ventral scales are seen in it. 



Middle Coal Measures, Jefferson Co., Eastern Ohio. 



HYLONOMUS Dawson. 



Hylonomus lyelli] Dawson, loc. cit. viii, 167. 

 The Joggins. I?bva Scotia Coal Measures. 



Hylonomus aciedentatus Dawson, 1. c. viii, 258. 

 Coal Measures ; with the last. 



Hylonomus wymanii Dawson 1. c. viii, 270. 

 Coal Measures, Nova Scotia ; with the last. 



PARIOSTEGUS Cope. 



This genus is represented by a large part of the cranium of a Batrachian 

 from the triassic coal measures of Chatham Co., North Carolina. If not a Ba- 

 trachian, it coiild only belong to a ganoid fish, but though some of its charac- 

 ters are somewhat ichthyic, it lacks the following important elements of the 

 ganoid structure, i. e., free post- and suborbital bones ; postnareal cavities ; 

 branchiostegal, and arched branchihyal bones. On the other hand it has a 

 large preorbital, bounding the frontal and maxillary to the nares, and the inner 

 border of the orbit as in Stegocephalous Batrachia ; also a postorbital element 

 contributing to the formation of an extended supratemporal roof. 



Contrary to what has been found the case in most genera of Stegocepbali, 

 the maxillary appears to extend posteriorly to a free termination, as in modern 

 Salamanders, and the supra-temporal bone presents a very prominent, obtuse, 

 arched margin. This margin extends from the orbits on each side, and is in- 

 curved towards the posterior part of the cranium. There is therefore no 

 quadratojugal piece. 



Tlie maxillary and mandibular pieces are slender, flat bones, as in Menopoma ; 

 the form of the posterior or articular portion of the latter cannot be ascertained 

 from the specimen. The more or less exposed part of the median region of the 

 latter exhibits a succession of shallow transverse notches, enclosing thirteen 

 obtuse elevations. The former resemble rudimental lateral alveoke for minute 

 pleurodont teeth. A few other similar minute ribs, and perhaps a minute 

 curved cone without sculpture, are the only other indications of dentition. 



The bones of the upper surface of the cranium are most readily interpreted 

 by reference to those of Menopoma. A pair of narrow nasals, acuminate be- 

 hind, penetrate between the frontals as far posteriorly as the posterior margins 

 of the orbits. The suture between these is very distinct, and entirely straight. 

 The preorbitals extend to above the orbits, and there appear to cease with a trans- 

 ■ verse suture. Between these and the nasals a broad triangular element eaters 



1868.] 



