WILLISTON : A NEW SPECIES OP SAGENODUS. 181 



A number of other bones of indeterminable relationsliiiDS are shown 

 in plates xxviii and xxxv, and there are several others too incomplete 

 to figure. They are for the most part thin, and probably represent 

 among them the pectoral and pelvic girdles in part. 



Numerous bones of the roof of the skull are in the collection. 

 Some of the more perfect specimens are shown in plate xxxv. The 

 surface exposed when in the rock is almost invariably the inner, since 

 the outer surface is more roughened and less easily separable from 

 the matrix. 



The material in which the bones occur is an exceedingly hard lime- 

 stone, permitting but very little manipulation. The bones exposed 

 are due to fortunate splitting of the matrix. Doubtless with more 

 comi^lete examination of the horizon in which they occur the com- 

 plete anatomy of these interesting dipnoans will be brought to light. 



