382 University Geological Survey of Kansas. 



Leptotrachelus [Dercetis] and Euryophilus discovered in the Chalk 

 of Mount Lebanon, convinced M. Pictet that they formed a 

 group naturally associated, especially by the great analogy af- 

 forded by the peculiar arrangement of the series of scutes, and 

 that they formed a family of the teleosteans, to which he gave 

 the above name." 137 



Cope long ago described three species and two genera of this 

 group of fishes from Dakota, which seem to have been over- 

 looked by subsequent writers. 138 Concerning the relationships, 

 he says: "The relationship of the family of dercetiform fishes 

 has been discussed by various authors, especially by Pictet and 

 Von der Marck. The former regards them as teleosts ; the 

 latter as ' ganoids.' As I do not adopt the division signified by 

 the last name, I find Professor Pictet's view nearer to the point. 

 The specimens indicate, further, that the Dercetidx belong to the 

 Actinopteri, and probably to the order Hemibranchii. The only 

 alternative is the order Isospondyli, and the characters which 

 separate the two are not clearly shown in the specimens. Dis- 

 tinct bones below the pectoral fins may be interclavicles, which 

 belong to the Hemibranchii." 



The genus Trisenaspis , from the Niobrara of Dakota, there de- 

 scribed, has the dorsal and ventral scutes triradiate, the median 

 branch of the three directed anteriorly, together with numerous 

 band-like scutes. Ichthyotringa Cope, from the same locality, has 

 the body covered with small, round scales. The third species is 

 Leptotrachelus longipennis Cope, in which the dermal scutes con- 

 sist of median, dorsal and ventral rows of tripodal form. 



From all these, as well as other forms, the present genus seems 

 distinct, though evidently nearest allied to Aspidopleurus Pictet 

 and Humbert, from the Lebanon Cretaceous. 139 



137. Davis, On the Fossil Fish of the Cretaceous Formations of Scandinavia, Trans. K03 al 

 Dubl. Soc, IV, p. 428. 



138. Bull. U. S. Geol. Surv. Terr., IV, 67. 



139. Pictet and Humbert, Nouv. rech. s. les. Poissons fossiles du Mont Liban, p. 109, pi. X, 

 fie:. 1 ; Davis, On the Fossils Fishes of the Chalk of Mount Lebanon, Trans. Royal Soc, III, pi. 

 XXXVIII, fig. 4. 



