DEVONIC FISHES OF THE NEW YORK FORMATIONS 1 2g 



besides, it is a well ascertained fact that the tubercles increase in size with 

 age. The median occipital has an extreme length of 5.5 cm, and thickness 

 of about 3 mm. The specimen is labeled as having been found " Sept. 9, 

 1851, in the Goniatite limestone' at Hendrick's ledge, west of Manlius, 

 N. Y." There is no catalogue number. 



Formation and locality. Marcellus division (Erian) ; New York. 



Dinichthys lincolni Claypole 



Plate 7, figures 4-6 



1893 Dinichthys li n colni £. JF. C/ay/'ale. Am. Geol. 12: 277, text fig. p. 276 

 1906 Dinichthys lincolni Z. Hussakof. Am. Mus. Nat. Hist. Mem. 9, p. 117, 

 142 



Known only by a single right vomerine tooth of about the size of the 

 corresponding element in D. i n t e r m e d i u s Newberry, and very similar 

 to it in general form. The external surface, however, not only along the 

 symphysial margin, but also over nearly all of the exposed portion, is cov- 

 ered with enlarged conical tubercles, or even denticles, which are arranged • 

 in more or less regular vertical series. The externolateral process which 

 serves for the attachment of the tooth to the preorbital, is well developed, 

 but distally somewhat compressed. 



The unique tooth upon which this species is founded possesses a num- 

 ber of interesting features. In the first place, as already noted by Claypole, 

 it is singular in having the entire outer face strongly tuberculated ; and it is 

 noteworthy that the tubercles are most conspicuously developed, so that 

 they become in fact denticles, along the inner or symphysial margin, thus 

 placing the species in close relation with D. herzeri. The dermal origin 

 of the different dental plates in Arthrodires could not be more distinctly 

 indicated than by these vestigial remnants of Uronemuslike tuberculation. 



Another point worthy of attention relates to the marks of contact with 

 the lower dental plates, such as are plainly visible on the inner or poste- 

 rior face of the tooth. It is evident that the larger and outer (ectad) prong 

 has been considerably worn down by use, and its lower extremity blunted ; 



' The Agoniatite limestone, which in the section referred to lies between the Marcellus 

 and Cardiff shales. 



