348 EXPLORATIONS ACEOSS THE GREAT BASIN OF UTAH. 



a general thing they are proportionally a little wider than usual; but they vary in this 

 respect, and beyond a doubt belong to this well-known species. 



I am not aware of this shell having been hitherto discovered at any locality within 

 the territory of the United States, so far west by between 1,000 and 1,200 miles. 



Locality and position. — Same as preceding. 



Atrypa aspera, Scb loth. 



Plate 1, fig. 2, a, 1>. 

 Twehratulites aspcr, Schlot, (1813), Min. Taschenb., vol. vii, pi. 1, fig. 7. 

 Mr mm u*i>rm, Dalm. (1S-27), Vet. Acad, liandl., pi. 4, fig. 3, and of many others (not J. Sowerby). 



? Atrypa ^)im>,a. Hall ( Ism Geol. Uv V t. 4th District New York.' 



The specimens here referred to the above well-known and widely-distributed 

 species are very small for that shell, and, being in a rather bad state of preservation, 

 cannot be identified wirli positive certainty. From their general appearance and asso- 

 ciates, however, 1 am led to regard them as probablv a variety of that species. It 

 should be explained here, however, that many reliable European authorities regard A. 

 aspera as only a more coarsely-marked variety of the common A. reticularis. 



Locality and position. — Same as last. 



CAKBONIFEKOUS FOSSILS. 

 M0LLCSCA. 



POLYZOA. 

 Genus ARCHIMEDIPORA, D'Orbigny. 



ARCHIMEDIPORA, (?) 



Plate 1, fig. 11. 



There are in the collection from the dark-colored limestones composing the hills 

 west of Camp Floyd, a few fragments of one or more species of this curious group of 

 Polygon; but as they merely consist of portions of the spiral axis, it is impossible to 

 make out their specific characters. They are both dextral and sinistral, quite slender, 

 and make about eight turns in the space of an inch. 



No species of this genus has hitherto been found in the region of the Rocky Mount- 

 ains, so far as known to the writer. Several species occur in the Lower Carboniferous 

 series of the Western States; though I believe we have yet no well-authenticated 

 instances of the occurrence of these forms in the Coal-Measure. 



Note. — Up to this time (November, 1875), I have seen no other specimens of this 

 genus from the Rocky Mountain region. 



BRACHIOPODA 



Genus CHONETES, Fischer. 



Chonetes Verneuiliana, var. Utahensis. 



Plate -2, fig. 2, a, h, c. 

 Chmetes Verneuiliana, Norwood and Pratten (1853), Jour. Acad. Nat. Sci. Phila.,111, 1, pi. ii, fig. 6. 



This little Chonetesw much like C. Verneuiliana of Norwood and Pratten; from the 

 typical form of which, however, it differs in having a much broader and more rounded 



