54 PEOCEEDINGS OF THE NATIONAL MUSEUM VOL.68- 



POLYGNATHELLUS CURVATUS. new species 

 Plate 1, fig. 4 



The specimen of Avhich the impression of the concave side is 

 shown in Figure 4 is supposed to represent a distinct species, differing 

 from the genotype in the much greater curvature of the plate as 

 seen in lateral view. The basal expansion is narrower and its sur- 

 face is not so distinctly tuberculated. In other respects the two 

 species are essentially the same. 



Occurrerice. — Devonian (Rhinestreet) : Shaleton, N. Y. 



H oloty pe.—C?it. No. 11305, U.S.N.M. 



Genus GNATHODUS Pander, 1856 



After much speculation as to what Gnathodus may really be, we 

 must admit failure to reach a satisfactory conclusion. All the 

 specimens we first believed to belong here have proved to be side 

 vieAvs of species of Polygnathus. It is possible that Pander's figure 

 of Gnathodus inosquensis may also be such a side view with the 

 crest showing the height of the posterior extension of the crest and 

 the plate crumpled or broken away. Bryant believed that the genus 

 might be retained and placed here an American Devonian species in 

 which the flanges of the plates are very little developed. This may 

 be true but we have seen no specimen Avhich conclusively estab- 

 lishes this view. For the jDresent we must leave Gnathodus out of 

 consideration in describing American conodonts. 



7GNATH0DUS. species 



Plate 1, fig. 5 



We have illustrated an example with the kind of appearance 

 that we had supposed might be referable to Gnathodus if that 

 should really prove to be a distinct genus. On further more careful 

 examination of this and similar specimens we were forced to the 

 conclusion that they represent merely side views of Polygnathus 

 forms with the crest shown in its full height and the expansions 

 making the plate broken. 



Occurrence.— DQxon\?ij\ (Rhinestreet) : Shaleton, N. Y. 



Genus CTENOGNATHUS Pander, 1856 



Considering C. mui^chlsoni as the genotype, this genus is of very 

 doubtful relations and may not be a true conodont at all. The 

 figures of the second species C. verineuilU suggest at least three 

 generic types, while the last species C. heyserlingi shows no charac- 

 ters definitely recognizable among any of our forms. Under these 

 circumstances Ctenxygnathus must be provisionally set aside as in- 

 sufficiently established. 



