144 CATALOG or FOSSIL FISHES IN THE MUSEUM 



Gyracanthus sp. 



(PL 52, fig. 4) 



E. 2489 A small, slender spine, imperfect at both ends, measuring 

 46 mm. as far as preserved. One face is rounded while 

 the other has a sharp ridge running the length of the 

 spine, somewhat nearer one margin than the other. It is 

 ornamented with two series of fine Hnes forming a V- 

 shaped arrangement, with the apices of the V's on the 

 ridge. The spine, from its form and ornamentation, 

 undoubtedly represents a species of Gyracanthus; but as 

 it may be an immature example, or possibly belongs to 

 G. sarlei, it seems to us undesirable to give it a name at 

 the present time. No doubt larger and better specimens 

 will some day be discovered. 



Conodont bed (Genesee); Eighteen Mile Creek, near 

 North Evans, Erie County, N. Y. Collected by W. L. 

 Bryant. 



///. Ichthyotomi 

 Genus Dittodus Owen^^ 



The teeth referred to the genus Dittodus belong to Pleuracanth 

 sharks. It is probable that they represent a number of genera, con- 

 sidering their great geological range and the fact that they come from 

 such diverse localities and formations; it therefore seems desirable 

 to retain Dittodus as a provisional genus rather than to refer all these 

 teeth to the genera Pleuracanthus and Diacranodus. 



Dittodus priscus (Eastman) 



(PI. 44, figs. 3, 3a, 3b; text-fig. 51) 



Diplodus priscus Eastman, Joum. Geol., vii, 490, pi. vii, figs, i, 2. 1899. 



This species has hitherto been found only in a peculiar deposit^^ of 

 Upper Devonic age near Elmhurst, Illinois. Associated with it is a 

 second species, D. striatus, distinguished by having much finer stria- 



° As pointed out by 0. P. Hay (Bibl. and Cat. Fossil Vert. N. A., p. 265), Diplodus is preoccupied 

 and should be replaced by Dittodus Owen, which is an available synonym. 



62 Waller, Stuart: A peculiar Devonian deposit in northeastern Illinois. Journ. Geol. vii, 483-488 

 3 figs, iSqq. 



