190 



BRITISH FOSSIL REPTILES. 



Fig. 1. — Section of tooth of Lahyrinlhodon. 



and with a subcircular transverse section : the surface was traversed by close-set 

 longitudinal lines, seemingly indicative of fissures. Being at tbat tinie engaged in 

 a study of the teeth of Vertebrates, I submitted the fossils to microsco])ical 

 scrutiny, and great was my surprise to see, in a transverse section, the structure 

 figured in the subjoined Cut, fig. 1. 



The question which chiefly interested 

 my geological friends was whether the 

 sandstone was, as tbey suspected, of 

 Triassic age, and might be eqiiivalent to 

 the German " Keuper Sandstone." Now, 

 from this sandstone had been obtained 

 fossils of a large Vertebrate species, 

 referred by Professor Jaeger^ to a genus 

 he termed Mastodon-saurus. Of this 

 species one of the fossil teeth presented 

 the same conical, transversely circular, 

 shape and longitudinal striation of tbe 

 Warwickshire fossil. I therefore wrote 

 to the author requesting the favour of a 

 tooth of the Mastodonsaurus, which was 

 promptly and kindly granted. Of this 

 tooth slide-sections for the microscope 

 were prepared and a labyrinthie interblending of the dental tissues was displayed, 

 identified with the structure so unexpectedly brought to light in the fossil teeth 

 from the Warwickshire Trias. Subsequent acquisitions of fossil remains, for which 

 I am indebted to Dr. Lloyd, of Leamington, have enabled me to add the following 

 illustrations of the osteological characters of the extinct form characterised by the 

 labyrinthie structure of its teeth. 



Species — Labyrinthodon Jaegeri, Owen. 



The first of these fossils here described indicated a species as large as the type 

 of Mastodonsaurus. It consisted of portions of two mandibular rami [Batrachia, 

 Plate 2) from diff'erent individuals. One, figs. 1, la, includes the angular, articular, 

 and hinder part of the dentary elements of the lower jaw, with portions of a score 

 of relatively small conical, nearly equal-sized teeth. The angle of the jaw termi- 

 nates obtusely, and is produced about three inches behind the articular surface. 



^ ' TJeber die fossilen Reptilien, welche iu Wiirtemberg aufgefuadeu wordea sind,' 4to, 1828, 

 pp. 35, .38, tab. 4 and 5. 



