1900.1] HAY—VERTEBRATES OF CARBONIFEROUS AGE. 97 
the matrix, so that with a little careful cleaning a mold was ob- 
tained, into which wax was pressed and thereby a satisfactory resto- 
ration of the tooth obtained. The tooth resembles most closely 
the figures of the species published in the second volume of the 
Geological Survey of Lllinois, Plate iv, Figs. 1-1°. The height of 
the longest cusp from the lower surface of the base of the tooth is 
zomm. ‘The edges of the compressed cusps had evidently been 
serrated. The base is prolonged backward, furnished with a button 
posteriorly and above, flat on the lower or attached side, and with 
a downwardly projecting tubercle near its front border. 
This species was originally reported by Dr. Newberry from the 
coal-measures of Linton, Ohio. In 1866 it was announced from 
the coal-measures of Posey county, Indiana. Mr. A. S. Woodward 
states that it has been found in Illinois, but he probably so inferred 
from its being described in the Illinois Geological Survey reports. 
So far as I am aware, it has not hitherto been known from that State. 
It furnishes another proof of the close relationships of the faunz of 
the Linton and the Mazon creek beds.  Destinez, as above cited, 
has reported the species from Belgium. 
DITTODUS LUCASI, sp. nov. 
This species appears to be quite distinct from any described up to 
this time. The possessor of this tooth has been a fish of considerable 
size. The height of the longer of the two prin- 
cipal cusps is 18 mm., that of the shorter 15 
mm., the measurements being made from the 
lower surface of the base. The tips are sepa- 
rated by a space of 16 mm. The cusps are 
compressed and furnished with carinz on the 
edges. The latter have not, so far as I can 
determine, been serrated. The form of the 
cusps does not differ essentially from those of 
D. compressus (Newb.). Between the main 
cusps, standing at the very front border of the tooth and projecting 
farther forward than the main cusp, is a very distinct median cusp. 
Its height, measured from the lower surface, has been about 7 mm., 
possibly more. The characteristic feature of the tooth is found in its 
small base. This, when compared with such aspecies as D. /atus, is 
weak. The width of the base (parallel with the jaw) is 10 mm.; 
the length (transverse to the jaw) is only 7 mm. On each side of 
Fic. 1. Dittodus lucasi. 
PROC. AMER. PHILOS. soc. xxx1x. 161. G. PRINTED APRIL 17, 1900° 
