MARYLAND GEOLOGICAL SURVEY 315 



The types are from the Eden shale of the Ohio Valley. In the Appa- 

 lachian Valley the species is known from the corresponding horizon in 

 southern Pennsylvania, the upper part (Eden) of the Martinsburg shale, 

 and also from the Sinuites bed. 



Occurrence. MARTINSBURG SHALE. Jordans Knob, one and one-half 

 miles northeast of Fort London; Chamber sburg ; two miles south of 

 St. Thomas, Pennsylvania ; Eickard Mountain, Maryland. 



Collection. U. S. National Museum. 



Family TROCHONEMATIDAE 



Genus STROPHOSTYLUS Hall 



STROPHOSTYLUS TEXTILIS Ulrich and Scofield 



Plate L, Figs. 31-36 



Strophostylus textilis Ulrich and Scofield, 1897, Minnesota Geol. Survey, Pal., 

 vol. iii, pt. 2, p. 1064, pi. Ixxxii, figs. 49-54. 



Description. " Shell rather small, 12 to 25 mm. high, 11 to 20 mm. 

 wide, obliquely conical; apical angle 60 to 70; whorls, in casts, three 

 or four, in entire shells, six or seven, increasing quite regularly in size 

 from the acute apex, almost uijiformly rounded, often with several widely 

 separated, deep, oblique constrictions; suture deep; aperture subovate, 

 oblique; inner lip appearing thin in a ventral view, but when a part of 

 the outer wall is removed it is seen that it forms a moderately thick 

 columella with a spiral fold beginning near the lower angle. In young 

 examples neither the fold nor a spiral furrow just above it is very distinct, 

 while in some cases the whole inner lip appears to be simple and thin as 

 in Holopea. Surface beautifully cancellated by subequal, fine, sharp, 

 revolving and obliquely transverse lines, the network growing strong 

 enough on the last whorl to be distinctly visible to the naked eye." 

 Ulrich and Scofield, 1897. 



The graceful form and beautiful markings of this shell are features 

 which aid in its ready recognition. 



Occurrence. MARTINSBURG SHALE (Sinuites bed). Chambersburg, 

 Pennsylvania. Black River and Trenton of Minnesota, Missouri and 

 Kentucky. 



Collection. TJ. S. National Museum. 



