298 Systematic Paleontology — Middle Devonian 



Occurrence. — Romxey Foioeation, Hamilton Member. East bank 

 Evitts Creek below Wolfe Mill. 



Collection. — Maryland Geological Surve}'. 



Genus DIAPHOROSTOMA Fischer 



DiAriiOROSTOMA LIXEATUM (Conrad) 



Plate XXXVTI, Figs. 7-12 



Platyostoma lineata Conrad, 1842, Jour. Acad. Nat. Sci.. Phila., vol. viii, p. 



276, pL xvii, fig. 7. 

 Platyostoma lineata Hall, 1879, Pal. N. Y., vol. v, pt. ii, p. 21, pi. x, figs. 1-21. 

 Diaphorostoma lineatum Clarke, 1901, N. Y. State Mus., Bull. 49, p. 131. 

 Diaphorostoma lineatum Clarke, 1903, N. Y. State Mus., Bull. 65, p. 533. 

 Diaphorostoma. lineatum Grabau and Shimer, 1909. N. Am. Index Fossils, 



vol. 1, p. 680, fig. 953. 



Description.- — "Shell siibovnte, approaching to subglobose; spire ele- 

 vated above the body-whorl, though varying in degree ; when entire, four 

 or five volutions, but seldom preserving more than three, the apex being 

 usually imperfect; the body-whorl usually verv ventricose, regularly con- 

 vex and a little depressed below the suture line; aperture suborbicular in 

 perfect specimens, sometimes subrhomboidal ; outer lip thin, with a sharp 

 entire margin, columellar lip thickened. Surface marked by fine, nearly 

 equidistant, thread-like revolving striae, which are cancellated by fine 

 concentric striae of about the same strength, but unequally distant. In 

 well-preserved specimens, the surface is beautifully cancellated and in 

 worn and partially exfoliated specimens, some remains of these surface 

 markings are usually visible." Hall, 1879. 



This species is not common in Marjdand but one specimen was obtained 

 which apparently clearly belongs to this species. It shows three volution* 

 of similar size, shape and appearance to the figures of this species from 

 the Hamilton of New York, with the exception that the median part of 

 the body-whorl is some^^'hat broadly ridged and not so regularly convex 

 from the upjier to the lower edge as represented in the figures. The 

 surface markings are well preserved on portions of the last two volutions 

 and show that it is beautifully cancellated, the revolving striae a little 



