4 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



published elsewhere (469), they are given the rank of orders all excepting the 

 Aistopoda, which are now regarded by the writer as specialized Microsauria. 



The recent Caudata are possibly represented in the North American Coal Meas- 

 ures by forms which may be assigned tentatively to the Proteida. Such forms as 

 Cocytinus gyrinoides, Hyphasma Icevis, and Erierpeton branchialis possibly represent 

 this group in the Pennsylvanian. This relationship is based chiefly on the structure 

 of the hyobranchial apparatus and on the general structure of the species. The 

 three above-mentioned species are, however, very insufficiently known, and the 

 relationship can hardly be regarded as more than suggested by the characters which 

 are at hand. 



The Salientia, or frogs, may possibly have their ancestral type in Pelion lyelli, 

 the first known species from the Linton, Ohio, Coal Measures. Oddly enough, 

 among the hundreds of specimens collected later from this horizon, not a fragment 

 can be identified with this species. The type specimen is unique, and although 

 incomplete its characters are suggestive. 



The Branchiosauria are represented in North America by four species: Mic- 

 rerpeton caudatum, Eumicrerpeton parvum, Mazonerpeton longicaudatum, and M. 

 costatum. Three other genera which occur in North America have been placed 

 (642) in this group, but they do not belong there, for reasons given below. The 

 branchiosaurs were salamander-like in appearance. They were naked, with the 

 exception of small ovoid scales on the back and the chevron-shaped armature of 

 the ventral surface, the latter being almost universally present among the Paleozoic 

 Amphibia. They were adapted for life in the water for at least the early part of 

 their existence, as is shown by the possession of gills on many of the late Carboniferous 

 and early Permian forms of Europe. The group is, without doubt, ancestral to 

 the modern Caudata. No branchiosaurians have been described elsewhere from 

 so low in the geological series as those here given and they are the first and only 

 evidence of the occurrence of the group in the western hemisphere. 



The Microsauria are represented in the Coal Measures by numerous forms which 

 are usually characterized as lizard-like animals with a well-developed ventral scu- 

 tellation. Other characters, such as the possession of lateral-line grooves on the 

 cranium, the arrangement of the cranial elements, and the condition of the ribs, 

 will be discussed further on. The pectoral arch is well developed and is composed 

 of five dermal bones plus the regular skeletal elements. The skeletal membrane 

 bones are sculptured after the manner of those of the cranium. The bodies of the 

 animals were, in a few cases, covered with scales; but most of them appear to have 

 been completely naked, even the ventral armature being absent in some cases. 

 The ventral scutellation was especially strong and highly developed in some of the 

 forms; e.g., in the genera Saurerpeton and Sauropleura. The vertebrae are uniformly 

 of the hour-glass or notochordal type. This is so generally the case that the 

 characters of the vertebrae and ribs are taken as the chief diagnostic characters of 

 the major groups. Various peculiarities are seen among the Microsauria, such as 

 the development of horns in various genera which are, apparently, related. The 

 order seems to have gone completely out of existence during the early Permian, 



