142 Annals of the Carnegie Museum. 



The identification of this shell is not entirely satisfactory, but the 

 Camarotcechia which is so abundant in the Three Forks shale is more 

 like this than any other described species. Some of the fully grown 

 shells agree very closely with Hall's description in volume IV, " New 

 York State Paleontology." They have about sixteen plications on 

 each valve, three of which are in the sinus and four on the fold. Other 

 specimens in the collection have one, two, or four plications in the 

 sinus and two, three, or five on the fold. 



Locality. — This is a common fossil in all the zones of the .Upper 

 Devonian with the exception of the white blocky shale. Nearly all 

 the specimens from the red fissile shale are of small size. Three Forks 

 and Logan, Montana. 



Genus Leiorhynchus Hall. 



Leiorhynchus mesacostale Hall. 



(Plate III, figures 8, 9.) 



Atrypd mesacostalis Hall, 1843. " Report of the Fourth District, Geology of New 

 York,'' p. 64, fig. I. 



Leiorhynchus mesacostalis WiW, 1867. '■^ Paleontology of New York,'' Vol. IV, p. 

 362, PI. 67, figs. 18-25. 



This is one of the abundant fossils in this fauna. The specimens 

 are moderately convex, transversely elliptical in outline, and usually 

 of somewhat smaller size than the specimens from New York. The 

 plications are entirely obsolete on the sides of most of the specimens, 

 and the number of plications in the fold and sinus is variable, ranging 

 from one to four in the sinus, and two to five on the fold. Half a 

 dozen specimens have been observed which show one or two faint pli- 

 cations outside the fold and sinus. 



Locality. — This species is common in the same zones as the pre- 

 ceding at Three Forks and Logan, Montana. 



Family SPIRIFERID^ King. 



Genus Spirifer Sowerby. 



Spirifer disjunctus Sowerby. 



(Plate III, figure 10.) 



Spirifer a disjtineta Sowerby, 1840. '■'■Transactions of the Geological Society,'" 2d 

 series, Vol. V, PI. 53, fig. 8; PI. 54, figs. 12, 13. 



Spirifer disjunctus Hall and Clarke, 1893. '■^Paleontology of New York," Vol. VIII, 

 pt. II, PI. 30, figs. 14, 15, 17. 



This species is quite abundant in the red fissile shales, and is note- 



