120 THE DEVONIAN OF MISSOURI. 



Surface, on the upper side of the volutions, usually marked by strong, regular, dis- 

 tinct striae, which often rise in sharp elevated ridges; occasionally finer and more sub- 

 dued. These striae are parallel to the lines of growth, and sometimes appear to have been 

 crenulated by finer revolving striae. A well-defined revolving band marks the periphery 

 of the shell, but usually (owing to compression of the specimens) this cannot be traced 

 in the higher volutions. The lower side of the outer volution is marked by fine, equal, 

 revolving striae." 



Remarks — The identification is uncertain as the Missouri specimens are all interior 

 moulds and none is perfect. The one figured is the most complete. 



Specimens from the Cedar Valley of Iowa have been referred to this species. 



Occurrence — Callaway limestone of Callaway and Montgomery Counties. 



Family Euompbalidae 



Genus Euomphalus Sowerby 



Euomphalus cj. hecale Hall 



Plate 28, figures 6, 7 



1876. Euomphalus Hecale Hall, Illustrations of Devonian Fossils; Gasteropoda, pi. 



16, figs. 10-14. 

 1879. Euomphalus Hecale Hall, Nat. Hist. New York, Paleontology V, pt. 2, p. 59, 

 pi. 16, figs. 10-14. 



Hall's description — "Shell discoid, spire depressed. Volutions about three or four, 

 contiguous, rounded, the inner ones slightly elevated above the plane of the outer one, 

 gradually enlarging from the apex, very slightly expanding at the aperture and flattened 

 on the lower side. Umbilicus broad, descending abruptly from the inner basal margin 

 of the volution, which is rounded on that side. 



Surface concentrically striated— the striae often crowded in fascicles or ridges 

 towards the aperture." 



Remarks — A rare form in the Snyder Creek shale. It is preserved only as internal 

 moulds and the identification is uncertain. The resemblance to E. inops Hall is very 

 close. 



Order Ctenobranchiata 



Suborder Platypoda 



Superfamily Taenioglossa 



Family Capulidae 



Genus Platyceras Conrad 



Platyceras cj. calantica Hall 



Plate 26, figures 9 and 17 



1859. Platyceras calantica Hall, Nat. Hist. N. Y., Pal. vol. Ill, pp. 328-329, pi. 62, 

 figs. 1-5. 

 Hall's description — "Shell obliquely or arcuately subconical; apex consisting of 

 one and a half to two minute volutions, from which the body of the shell expands very 

 abruptly, becoming extremely ventricose below and broadly campanulate at the aper- 

 ture; peristome scarcely sinuous. 



Surface marked by fine transverse striae and a few broad shallow wrinkles." 

 Remarks — We have only one well-preserved specimen in our collections. The 

 reference to a Lower Devonian species seems questionable but its agreement in shape is 



