Review of Recent Geological Literature. 
247 
Now, the Italian paleontologists have demonstrated, by means of the 
more or less complete dentition occurring in situ , that over half a dozen 
Tertiary species of Oxyrhina founded on detached teeth are identical 
with the common O. hastalis ; and that at least three “species” of 
fossil Car char odon teeth represent merely different portions of the 
dentition of C. rondeletti , which is still existing. By analogy, then, 
we should expect that the complete dentition of C. auriculatus , which 
is the type of Carcharodon teeth having large lateral denticles, would 
reveal a series of teeth differing among themselves to a like extent; and 
such an amplitude would abundantly include all of the forms which 
Woodward and others hold as synonymous with C. auriculatus , but 
which Jaekel regards as distinct. 
The author’s failure to take the variations due to the relative position 
in the mouth sufficiently into account is shown in yet another instance, 
where he describes certain small teeth of Carcharodon turgidus as per¬ 
taining to the symphysis. Although admitting that symphysial teeth 
are absent in the recent species of Carcharodon, he can conceive of no 
other explanation of their origin, “unless, indeed, they should be of 
pathologic nature.” A more careful comparison of these teeth with the 
dentition of recent Lamnidce would doubtless have convinced the au¬ 
thor that they occupied the posterior angles of the mouth; or, to adopt 
the term first suggested by Dr. Otto Reis, they are “Mundwinkelzahne.” 
Apart from these minor defects the paper is an excellent one and forms 
a welcome addition to our knowledge of the fossil fish fauna of Russia. 
c. R. E. 
The Geological Structure of the western part of the Vermilion Range , 
Minnesota. By Henry Lloyd Smyth and J. Ralph Finlay. (Trans. 
Am. Inst. Mining Eng., Atlanta meeting, 51 pp., 1895.) After brief ref¬ 
erences to the work of earlier geologists on the rocks and the structure 
of the region the authors divide the sedimentary rocks of the Vermilion 
range into two divisions, viz., a slate formation and the iron-bearing 
formation, of which the former is the older. This succession they de¬ 
duce from an examination of numerous outcrops on the shores of Ver¬ 
milion lake and about the mines. Although on page 8 they state that 
the iron formation is “to all appearance quite devoid of clastic mate¬ 
rial,” it has “clearly the structure of sedimentary rock” (p. 11). They 
suppose that the strata have undergone profound chemical rearrange¬ 
ment. The slate formation is less changed—a fact which is believed to 
be due to their “poverty in coarser detrital materials,” to their chemi¬ 
cal composition and to their extremely fine grain. As to the origin of 
the silica of the jaspers, the authors are inclined to consider it as the 
ultimate product of oxidation from some earlier sedimentary rocks. 
The igneous rocks of the region they consider wholly intrusive and of 
later date than the sedimentary—whether acid or basic. The acid ig¬ 
neous rocks were originally in the form of quartz porphyries and fel- 
sytes, but by fracture, pressure and shearing have been converted into 
sericite schists and breccia conglomerates. They involve fragments of 
the slate formation and of the jaspers, but only as portions “plucked 
