VERTEBRATE FOSSILS 573 



gosaurus and other stegocephalous Batrachia, but which also exists, according 

 to Gunther, in the Hving Rhynchocephalous hzard, the Sphenodon of New Zea- 

 land. The bones of the Hmbs and the scapular arches are decidedly reptilian, 

 and so unlike those of any Batrachia with which we are yet acquainted, that I 

 am disposed to refer them to the former class. And as there are several points in 

 which the fossils resemble the order Rhynchocephalia, I refer them provisionally 

 to that neighborhood. They constitute the first definite indication of animals 

 of that type in the western hemisphere. 



Associated with these saurians were found the teeth of two species of fishes 

 which are important in evidence of the position of the beds in which they 

 occur. One of these is a new species of Ceratodus, Ag., and the other a Diplodus. 

 The former genus is characteristic of the Triassic period in Europe, one species 

 having been found in the Oolite. It still lives in North Australia. In both of 

 these respects the Rhynchocephalian lizards present a remarkable coincidence. 

 They also belong to the horizon of the Trias in Europe; and the only living 

 species is found in New Zealand. Thus it would seem that a fragment of this 

 fauna, so ancient in the northern hemisphere, and so remarkably preserved in 

 the southern, has been brought to light in Illinois. It must be added in reference 

 to the geological age of the fossils, that the genus Diplodus has not yet been dis- 

 covered above the Carboniferous, and that one genus of the Rhynchocephalia 

 belongs to the Permian of Germany. We therefore wait further material before 

 venturing to decide whether they belong to Triassic or Permian time. 



In May, 1877, he read a paper before the American Philosophical 

 Society in which he reaffirmed the probable Permian character of 

 the beds:^ 



After an examination of the first fossils from this fauna which came under 

 my observation, I left the question undecided as to whether its characters pointed 

 to the Triassic or Permian Age. The Reptilia and a Ceratodus pointed to the 

 former; the Diplodus pointed even to the Coal Measures. The additional evi- 

 dence adduced in this paper adds weight to both sides of the question. Of the 

 fishes added, Ctenodus is a genus of the Coal Measures, and while Strigilina is 

 new, its affinities are to the Petalodont genera of that formation. On the other 

 hand the reptilian character of Clepsydrops is established, and the number of 

 its species is increased. Now the Coal Measures have nowhere disclosed rep- 

 tilian remains, so far as we have determinations of a reliable character; Batrachia 

 were the only type of air-breathing vertebrata known to that epoch. The present 

 fauna must then be placed above the Coal Measures, and the horizon will corre- 

 spond more nearly with the Permian than with any other embraced in the system. 



From its most characteristic fossil, the bed might be called the Clepsydrops 

 shale. Its position according to Dr. Winslow is near the top of the Coal Meas- 

 ures, and is marked No. 15, in Professor F. H. Bradley's section of the Coal 



I Am. Phil. Soc. Proc, 1877, Vol. XVII, p. 64. 



