DEVONIAN SPECIES. 49 



farrow along some of the anterior ones. The surface is nearly smooth, or 

 only has a few very small granules near the lateral margins. 



I place this species along with the Devonian fossils only because it 

 came from the same locality (and the specimens are in the same kind of 

 matrix) as that from which the other forms, apparently of Devonian age, 

 figured on the same plate, were obtained. In some of its characters, so far 

 as known, it resembles Upper Silurian forms quite as much as, or even more 

 than, Devonian ; and, as Mr. King infonns me that it came from the lowest 

 bed at the locality, it may possibly belong to the Upper Silurian. 



Locality. — Three miles south of Piiion Pass, Pifion Range, Nevada. 



PROETIDiE. 



Genus PROETUS, Steininger. 

 Proetus (Photon) denticulatus, Meek. - 



Plate 1, figs. 10, 10 a, and 10 6. 



I have only seen fragments of this species, consisting of the pygidium, 

 the glabella, and detached thoracic segments. As these parts have not been 

 seen united, of course it is possible that they may belong to more than one 

 type; and, to prevent confusion, if this should be found to be the case, 

 the pygidium, represented by fig. 10 a, is regarded as belonging to the 

 typical form of the species. From the manner in which these dififerent 

 parts occur associated together, however, it is quite probable that they all 

 belong to the same species. 



The pygidium is transversely subelliptic, and is nearly twice as wide 

 as long, with a moderate convexity. Its mesial lobe is about as wide ante- 

 riorly as each lateral lobe (exclusive of their lateral spine-like projec- 

 tions), and more prominent than the latter, with three or four segments. 

 The lateral lobes are rather depressed, and show about four segments each ; 

 these segments are not well defined, but have each a distinct mesial furrow, 

 extending out to the margin, where each segment terminates in a short 

 spine, directed backward; while there are two other smaller spine-like 

 projections just behind the posterior end of the mesial lobe ; thus making 

 ten of these projecting points to the whole of the free postenor and lateral 



4 P R 



a 



