FOSSILS OF THE DEVONIAN. 131 



rocks of Belgium, a new specific designation is given in honor of the origi- 

 nal discoverer of the species 



Formation and localities. Lower and upper horizons of the Devonian 

 limestone, west slope of County Peak, and Rescue Hill, Eureka District, 

 Nevada. 



Productus (Productella) navicella Hall. 

 Plate xiii, fig. 9. 



Productus navicella Hall, 1857. Tenth Ann. Eep. N. Y. State Cab. Nat. Hist., p. 172. 

 Productella navicella Hall, 1867. Pal. N. Y., vol. iv, p. 156, pi. xxiii, figs. 1-3, 9-11. 



The specimens referred to this species from the Upper Helderberg and 

 Hamilton Groups of New York are distinguished by their narrow, elon- 

 gate form, extreme arcuation, and strong costse on the lower half of the 

 shell that are extended upward as little ridges formed by the spine bases. 

 The specimens representing the species in Nevada are a little more elongate 

 than the average of the New York forms, and the radiating costse are some- 

 what stronger, otherwise the two are identical. 



Formation and locality. Lower horizon of the Devonian limestone, 

 south ridge of Atrypa Peak, Eureka District, Nevada. 



Productus (Productella) truncatus Hall. 

 Plate xiv, fig. 2. 



Productus truncatus Hall, 1857. Tenth Ann. Eep. N. Y. State Cab. Nat. Hist., p. 171. 

 Strophomena pustulosa Hall, 1843. Geol. Eep. Fourth District New York, p. 18. 

 Productella truncata Hall, 1867. Pal. N. Y., vol. iv, p. 160, pi. xxiii, figs.12-24. 

 Not Productus pustulosus Phillips. 



This pretty little species occurs in the Lower Devonian beds, and pre- 

 sents the characters of the specimens from the Marcellus shale of New York. 



In his remarks on this species, Professor Hall states that, on the author- 

 ity of M. de Verneuil, Strophomena pustulosa, a species founded apparently 

 on a dorsal valve of this species, has been referred to Productus (Stropha- 

 losid) MurcMsonianus M. de Koninck, which is likewise regarded as iden- 

 tical with the species Professor Hall described as Productus SJiumardianus. 

 Professor Hall has shown that P. (P.) truncatus possesses features not ob- 



