12 



THE EXTINCT BATRACHIA, EEPTILIA 



DENDRERPETON", Owen. 

 Journal Geological Society, London, 185n, p. 81. 



In the form of the cranium this genus differs from Brachydectes and oestocephalus 

 much as Menopoma does from Amphiuma. Two species appear to have Left (heir remains 

 in the coal measures at Linton, Ohio. 



There is an internal as well as an external suries of maxillary teeth in this genus, and 

 a vomerine patch, according to Dawson. The skin was ornamented with osseous scales 

 of an oval form, some of which were longer than others, and formed crest-like series along 

 the side. In a specimen of the mandible of the 1). acadianum, kindly sen!, me by Prof. 

 Dawson, the inflection of enamel at the base of the tooth is readily observed, but it appears 

 to ho as smooth as in any other type of the Microsauria above the alveolar margin. 



Fig. 1. 



AW 





DENDRERPETON OBTTJSUM, Cope 



This species is known by a partially preserved cranium. Tho 

 superior surface is exposed) the outlines of the jaws and orbits are 

 well preserved, with the occipital condyles. The os quadratum is 

 directed obliquely backwards, and the angle of the mandible extends 

 to a line a little behind that of the occipital condyles. The 

 zygomatic arch exists in a position similar to that in which it may 

 be seen in a few genera of A.nura, as Discoglossus and Pelobates. 

 It extends downwards and forwards from the supra-squamosal to the 

 maxillary region, but whether it is homologioally squamosal or 

 malar the specimen cannot show. The postorbital is present as 

 well, and with the last, and the supratemporal, forms the bony roof 

 of tho temporal fossa,. A piece which may be the pre and post 

 frontals combined, borders the inner superior margin of the orbit, it 

 widens posteriorly, where it has contact with the parietal, etc., and 

 narrows in front. Supraoccipitals form together a broad triangle 

 on the upper plane of the cranium, of less extent than the adjoining 

 supratemporal. These elements are pitted, and towards their 

 margins radiate grooved. These sculpturings grow less on the 

 margins of the supratemporal, and the portions of the surface of the more anterior elements remaining, are so slightly 

 marked as to give the impression that, the sculpturing in this species is much less than In othersof the genus. A few 

 beaded ridges are all that remain on the parietals and postorbitals ; the mamillaries have a slighl ly stronger sculpl lire 

 seen in a lew spots. 



The general form of skull is elongate behind, and much shortened in front of the orbits. The orbits are thus 

 altogether in front of a line equally dividing the cranium transversely, while in the D. acadianum they are in the 



middle of the skull. The outline of the muzzle in our species is then broad, rounded, as in the Menopoma alle- 

 gheniensis, while in the latter it, is ovate and produced. It therefore resembles also in its proportions the genus 

 Herpctocephalus lluxl, from the Irish Coal Measures. 



The parietal bones extend to opposite the posterior margins of the orbits, are then gradually contracted, and 

 form an acuminate prolongation on each side the wedge-shaped frontals. The prefrontals are thickened on each side 

 the front, behind the external narcs. The sutures defining the frontals anteriorly, tho nasals, and the premaxillaries 

 behind cannot be made out. The median longitudinal suture is a marked and zigzag one, and can be seen as far 



