118 THE DEVONIAN OF MISSOURI. 



Plenrotomaria providencis Broadhead 



Plate 26, figures 19 and 20 



1S96. Pleurotomaria Prcvidencis Broadhead, Am. Jour. Sci., 4th Ser. II, pp. 237-239, 



figs. 1-7. 

 1918. Pleurotomaria providencis Branson, Geology of Missouri, pp. 100-101, pi. 3, 

 fig. 12. 



Broadhead's description — "Shell subglobose, depressed, spire moderately elevated. 

 Volutions three or four, the last whorl much expanded. Aperture circular. Surface 

 marked by numerous striae or lines of growth which are occasionally imbricated, strongly 

 marked and unevenly fasciculated. 



A sulcus one-tenth of an inch broad and about one-half as deep divides the upper 

 and lower part of each whorl. The striae as they pass from the suture curve backwards 

 increasing in curvature as they approach the median sulcus, where they are so much 

 crowded as to form a low border to the sulcus. In crossing the sulcus they are concave 

 in front. On the lower side of the sulcus they also curve backward and form a sharp 

 border to the sulcus similar to that formed above. 



In average-sized specimens there is a row of prominent nodes about half way between 

 the sulcus and the suture. These nodes at their upper and lower portions are elongated 

 into a low ridge which follows the direction of the lines of growth of the shell, but in 

 soon blended into the body whorl. There is also another range of nodes below the sulcus 

 and sometimes a faint appearance of a second row. The shell also presents a somewhat 

 nodular appearance just below the suture. The suture is well defined. 



The lower side of the last volution is regularly curved, the upper side more often 

 rough-looking from the presence of nodes and the occasional prominence of the lines 

 of growth. 



On the last volution of old shells the nodes almost disappear but the sulcus con- 

 tinues to be well marked. Columellar lip thick, flattened, making an angle of about 80 

 degrees with the outer surface of the shell. 



Height of an average specimen 2 inches. 



Breadth of an average specimen 2 inches. 



Some shells are one-half larger." 



Remarks — Superficially this form resembles Turbo shumardi De Verneuil, but it 

 has a well marked slit which distinguishes it generically from Turbo. The nodes empha- 

 sized by Broadhead are really high parts of swollen ridges. The slit is peculiar in narrow- 

 ness and the sulcus in depth. Broadhead's cotypes are in the museum of the Uni- 

 versity of Missouri. His figure 6 is of a badly crushed specimen and the specimen from 

 which figure 1 was drawn is crushed and broken. The specimen figured in the Geology 

 of Missouri was carefully prepared by D. K. Greger. It was formerly in the collection 

 of the University of Missouri, but has disappeared. The University collection con- 

 tains more than 40 specimens collected from the Cooper near Providence, Missouri. 

 Specimens are abundant at one locality in the Cooper of Marion County. 



Genus Euryzone Koken 



Euryzone mineolaensis n. sp. 



Plate 26, figure 18; plate 28, figures 8 and 9 



Description — Shell turreted, slightly higher than wide; volutions about four, some- 

 what rapidly increasing in size, regularly convex, gradually expanding to the body whorl, 

 which is ventricose; no umbilicus; aperature oval, somewhat wider than high, surface 

 marked by numerous concentric striae which are directed gently backward from the 

 suture and curve backward strongly over the peripheral band. The band is five times 

 the width of the whorl, simple and slightly depressed at the margins. 



