DENTITION OF SOME DEVONIAN FISHES 33 
was fortunate enough to secure at the typical Milwaukee locality 
the specimen shown in Fig. 1. 
The inner face of this specimen is attached to a block of 
limestone, a part of the anterior extremity is broken away, and 
a considerable portion of the posterior end is missing. The 
total length may be estimated at about 24°, the proportions 
being about the same as in D. curtus, and about three quarters 
the size of an adult individual of D. zntermedius. The posterior 
aus) 
Fig.1. Dinichthys pustulosus E. Hamilton; Milwaukee, Wisconsin. Left mand- 
ible Ge. 
end is more slender than in either of these species, and the cut- 
ting edge also differs in having no prominence back of the tooth- 
like beak. The cutting edge of D. intermedius has one such 
prominence, and that of D. curtus two. In D. curtus ‘the posterior 
end of the cutting edge is set with two or three unequal denticles 
in place of the series of even, lancet-like points in the same 
position on the mandible of D: tntermedius.”’* But in the present 
form these denticles are reduced to mere swellings, of which five 
may be counted along the posterior slope of the cutting edge. 
Professor Udden’s specimens, altho smaller, shows the bosses 
more prominently; they are, in fact, rudimentary denticles, and 
represent the initial stage of those structures which are such a 
conspicuous feature in D. herzeri of the Ohio Shale. 
* NEWBERRY, J. S., Pal. Fishes N. A. (Mon. U. S. Geol. Surv., Vol. XVI, p. 156), 
1889. 
