EASTMAN: CARBONIFEROUS SHARKS. 59 
Plates 2 and 3 was obtained a number of years ago by Mr. G. C. Merrill 
from the Upper Coal Measures of Osage County, Kansas, and is preserved 
in the Museum of Comparative Zodlogy at Cambridge (Cat. No. 749). The 
second example, shown in Plate 1, was derived from the Upper Coal Meas- 
ures of Cedar Creek, Nebraska, and belongs to the Museum of the Nebraska 
State University at Lincoln. To Professor Edwin H. Barbour, Director 
of the University Geological Survey of Nebraska, the writer is greatly 
indebted for the privilege of studying and describing this and numerous 
other Carboniferous fish remains which have been collected during the 
prosecution of the Survey. Acknowledgments are also due to Miss 
Carrie A. Barbour, of Lincoln, through whose skill and zeal these speci- 
mens have been beautifully prepared or otherwise rendered available for 
study. 
It is stated by Professor Barbour that when his specimen of the sym- 
physial dentition of Campodus was discovered, it was in almost perfect 
condition, and the slight injury it sustained on being extricated from the 
matrix was subsequently repaired by his sister. For instance, a number 
of the coronal buttresses on one side, and several of the coronal apices 
were broken off ; such of these as could not be mended from the original 
fragments are now restored in plaster. As seen in Plate 1, the two 
posterior coronal apices, and also the fourth and fifth counting from the 
proximal end, are partly restored ; the remainder are in their original 
condition. Weathering has removed most of the enamel from this 
specimen, and indications of wear during life are not readily discernible. 
The Nebraska specimen is important from the fact that it first led to 
an adequate understanding of the earlier known Kansas example, which 
in turn disclosed a wealth of information respecting ancient types of 
Cestraciont dentition, and furnished the solution of a number of debated 
problems. For in the state in which the Kansas dentition originally 
came to the Harvard Museum, all of the coronal apices having been 
broken away, the complete form of the symphysial teeth was not re- 
vealed, and their relations to Edestus were unsuspected. That this 
specimen long ago challenged the attention of paleichthyologists, 
although no record of their views concerning it has come to light, is 
witnessed by the fact that plaster casts were taken from it at the direc- 
tion of Mr. Orestes St. John, while he was Assistant in Paleontology at 
the Museum under Professor Agassiz. Some of these replica, together 
with casts of the lateral series described by St John and Worthen in 
1875, have since found their way into other collections. 
From this statement regarding the history and condition of these 
