200 PALEONTOLOGY OF THE EUREKA DISTRICT. 



Surface of both the inner and outer walls smooth. 



Dimensions: the largest tube obtained has a length of ll mia and a 

 diameter of 0.5 mm . 



This species is closely allied to Coleoprion f Bohemicum Barrande (Syst. 

 Sil. Boheme., vol. iii, p. 109, pi. xv, fig. 15) from the Upper Silurian of Bo- 

 hemia. 



The surface characters of the Bohemian specimen are unknown, and 

 we would hesitate in identifying a species of this character from the sum- 

 mit of the Devonian in Nevada with one from the Silurian of Bohemia even 

 if more was known of each than is at present 



The Nevada species was gregarious, the little slender tubes now lying 

 thickly in the shale; some of them have a smooth, shining surface. The 

 shell is rather thick. 



Formation and locality. Upper Devonian, White Pine shale, on the 

 south slope of Diamond Peak, Eureka District, Nevada. 



CEPHALOPODA. 

 Genus ORTHOCERAS Breynius. 



Five species of Orthoceras are recognized among the numerous frag- 

 ments from the lower horizon of the Devonian limestone. None of them, 

 however, are sufficiently represented to be characterized as specifically dis- 

 tinct from described species, and their further determination, beyond a note 

 of the characters of each, is deferred until more and better material is col- 

 lected. 



I. Shell robust, straight, elongate. Transverse section circular in un- 

 compressed specimens. Apical angle about 15, measuring the septate 

 portion. Chamber of habitation and initial point unknown. Air-chambers 

 numerous and shallow, having a depth of about 5 mm where the diameter is 

 25 mm . Septa thin, the concavity equal to the interspaces. Sutures gently 

 curved, but not oblique to the axis. Siphuncle central; small at its inser- 

 tion in the septa; its passage through the interseptal spaces has not been 

 observed. Test removed from all observed specimens. There is a large 



