1897.] NEW YORK ACADEMY OF SCIENCES. 299 



figured two teeth from this formation, having triangular outlines 

 and different forms of crown from any before known. To these 

 the generic name Trigonodus was given. Subsequently Mr. 

 Orestes St. John, having access to the magnificent collections of 

 fish teeth belonging to Mr. Yan Home, Mr. Wachsmuth and Mr. 

 Springer, was able to bring into their relations many of the 

 scattered teeth of the Lower Carboniferous limestone and recon- 

 struct the dentition of the ancient sharks much moi'e completely 

 than had been before possible. 



Referring to Deltodus complanatus, in Vol. YII. of the Report 

 of the Geological Survey of Illinois, p. 184, he calls it a Sanda- 

 lodus and unites with it Trigonodus major. The latter union is 

 doubtless well founded, but I am unable to accept his views in 

 regard to the generic relations of the species to which both forms 

 of teeth belong. I have recently received from Mr. W. F. E. 

 Gurley, of Danville, 111., a large collection of the remains of 

 Elasmobranch fishes. Among these are many teeth of Deltodus 

 complanatus which prove bej'ond question that this should be 

 considered a Deltodus and not a Sandalodus. In order that 

 some of this evidence shall be judged by others I publish here- 

 with a number of figures photographed from specimens in Mr. 

 Gurley's collection. I think it will be agreed by all that they 

 represent teeth of Deltodus and not Sandalodus. Indeed among 

 all the fish teeth from the Burlington limestone which I have 

 yet seen I have not detected a tooth of Sandalodus. 



Deltodus spatulatus, N. & W. 

 PI. XXIY., figs. 8-11. 



(Among the specimens in the Gurley collection were a number 

 of well preserved dental plates which Dr. Newberry referred to 

 Deltodus spatulatus (Burlington group). (N. & W., 1866, Geol. 

 Survey of Illinois, Yol. II., p. 100.) A number of figures of 

 these plates were prepared for publication in the present paper ; 

 but the editor can find none of Dr. Newberry's notes relating to 

 them. He has accordingly selected but four of these figures 

 for comparison with D. complanatus. They may at the same 

 time serve to illustrate the author's views regarding the varia- 

 tional characters of this species. — Ed.) 



Sandalodus ellipticus, n. sp. 



n. XXIY., fig. 12. 



Terminal tooth long-elliptical in outline, one and three-quarter 

 inches long by three-quarters of an inch wide, strongly arched 



