I40 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



Type : It is impossible to determine which one of the specimens is the type. There 

 are numerous representatives of the species, as follows: Nos. 140, 1096 G, 8345 G, 

 8555 G, 1089 G, 2, 132, 133, no number, 1094 G, 8545 G, 8677 G, 1159 G, 105, no 

 number, 1091 G, ^a, 1092 G, 1093 G, 1095 G, 153, and others unnumbered in the 

 American Museum of Natural History; in the U. S. National Museum are the fol- 

 lowing: Nos. 4458, 4463, 4464, 4514. (Plate 20, fig. 2.) 



Horizon and locality: Linton, Ohio, Coal Measures. 



The most abundant species of the Linton Coal Measures. There are over three 

 dozen specimens preserved in the Newberry collection. The species is a clearly 

 marked one, as a rule, though there is great variation in the size of the body and the 

 form of the vertebrae. Though there are several apparently complete skulls pre- 

 served in the collection, it is impossible to make out the morphology of the ele- 

 ments on account of the amoimt of crushing to which the skulls have been subjected. 



The head is lancet-shaped, and the muzzle very elongate, slender, and acute at 

 the extremity. The head is in fact 

 a miniature of an ichthyosaur 

 cranivun. (Plate 20, fig. 2.) The 

 orbits are large and posterior to 

 the median line. The anterior por- 

 tion of the skull is narrow, poste- 

 riorly trvmcate, and the mandibular 

 angle is projecting. The posterior 

 portion of the mandible is sculp- 

 tured. Possibly the entire cranium 

 was also, and this has been lost; 

 in fact, this sculpturing is indicated 

 in one or two specimens. The teeth 

 are conical and sharp, longitudi- 

 nally striate, and anisodont. There seemstobe evidence of palatineor pterygoid teeth, 

 though this needs confirmation. The pectoral plates are well preserved, with the 

 interclavicle a narrow oval, with anterior and posterior prolongations. In one speci- 

 men it is sculptured. The clavicles are narrow and slightly sculptured. The abdom- 

 inal scutcllae are bristle-like. 



The vertebrae are short, with expanded neural and haemal spines. The expanded 

 condition of the nevu-al spines begins over the thoracic region, where they are low. 

 They become well developed in the posterior dorsal region. The caudal fan-shaped 

 spines are larger. The dilated portions form equilateral triangles which stand on 

 moderately short pedicels. They are weakly ridged, and each ridge is prolonged into 

 a narrow acute tooth beyond the margin, 1 1 of which may be counted on one of the 

 best-preserved spines. The longitudinal striae are terminated near the pedicel by 

 two others which cross obliquely from each side, and, meeting, present the appear- 

 ance of the margin of a cup sculptured in relief, from which the striae arise. Pedicels 

 smooth. The spines are in contact at their angles, thus forming a continuous line. 

 In a typical specimen there are 6 in half an inch, in another 7, and in a third 8. The 

 ribs are well-developed and slender. 



Fig. 30. — Restoration of P/yowiMi. X i. 



