86 C. R. Eastman — Tamiobatis vetustus. 



few minute fragments of Bryozoa and Foraminifera, them- 

 selves incapable of precise determination, no accompanying 

 structures were observed. Hence, the only intrinsic evidence 

 as to geological age is that afforded by petrographical charac- 

 ters, and by a study of the fossil itself. But neither class of 

 intrinsic evidence can be altogether relied upon in the present 

 case, owing chiefly to insufficiency of material for comparison ; 

 and beyond conceding that the specimen is undoubtedly Palaeo- 

 zoic, we must content ourselves with a statement of opinion 

 that it belongs to such or another horizon. Professor ]N. S. 

 Shaler, formerly state geologist of Kentucky, is inclined to 

 believe it is from the Waverly group. Mr. Charles Schuchert, 

 who is also familiar with the stratigraphy of the region, ven- 

 tures the opinion that it was derived from the Corniferous or 

 its equivalent. No other formations besides the Devonian and 

 Carboniferous are represented in the eastern part of Powell 

 County ; and this is far beyond the limit of transported mate- 

 rial. We may therefore feel a reasonable amount of assurance 

 in assigning our fossil provisionally to the Middle or Upper 

 Devonian. 



Description of the remains. — A very fair representation of 

 the specimen is shown in Plate I, and also in the accompany- 

 ing text-figure, both being of two-thirds the natural size. 

 Obviously it is the cranium of a fossil Elasmobranch, seen 

 from the dorsal aspect ; and the characters which at once sug- 

 gest affinities with the rays are the elongated rostrum, promi- 

 nent nasal capsules, and antorbital processes for attachment 

 with the pectoral fins. The general form of the skull is fiddle- 

 shaped ; there are evenly-rounded cavities for the eyes ; the 

 position of the hyomandibular and foramen magnum is indi- 

 cated ; and the median fontanelle as well as openings for the 

 passage of nerves are perfectly distinct. A fontanelle proper 

 does not occur in sharks, the cranial cavity being open in front ; 

 and although the tegmen cranii now under discussion differs 

 considerably from existing rays, the above enumeration of 

 features shows that it is decidedly more skate-like than shark- 

 like. 



The extreme length of the cranium is 16 cm , and its width 

 between the tips of the antorbital spurs is ll cm . It is quite 

 possible that the anterior portion of the rostrum is broken off, 

 although an expansion occurs at the forward part which appears 

 to have been symmetrical and normal. If the rostrum were 

 actually as short, and terminated in the manner shown, a resem- 

 blance is to be noted to the conditions existing in Torpedo, 

 Narcine, and others of the electric rays. But the cutwater is 

 wider, heavier, and less tapering than in recent forms ; and the 

 median fontanelle does not appear to have extended forward as 



