308 Systematic Paleontology — Middle Devonian 



appears to be closely related to 0. hehryx, if not identical, shows trans- 

 verse striae crossed hy longitudinal ones giving the surface a reticulated 

 appearance somewhat similar to that of 0. linteum Hall. 



Length of living chamber, 59 mm. ; width near larger end, 48 mm. ; 

 length of six air-chambers following chamber of habitation of another 

 specimen, 50 mm. 



Occurrence. — Romney Formation, Hamilton Member. Oldtown 

 Road near Cumberland ; west of Lock No. 56 at Great Cacapon ; on Old- 

 town Road east of Maryland Ave., Cumberland; on road east of Pine Hill 

 about 4 miles north of Oldtown. 



Collection. — Maryland Geological Survey. 



Orthoceras subulatum Hall ( ?) 

 Plate XXXIX, Figs. 1, 2 



Orthoceras subulatum Hall, 1843, Geol. N. Y., pt. iv, p. 180, fig. 1. 

 Orthoceras subulatum Rogers, 1858, Geol. Penna., vol. ii, p. 826, fig. 654. 

 Orthoceras subulatum Hall, 1862, Fifteenth Rep. N. Y. State Cab. Nat. Hist., 



p. 77. 

 Orthoceras subulatum Hall, 1879, Pal. N. Y., vol. v, pt. ii, p. 283, pi. xxxviil, 



fig. 3; pi. Ixxxiv, flss. 1, 2, 4, 6-10; pi. Ixxxvi, figs. 1, 2. 

 Orthoceras subulatum Grabau, 1899, Bull. Buffalo Soc. Nat. Sciences, vol. vi, 



p. 288, fig. 221 on p. 287. 

 Orthoceras subulatuvi Clarke, 1903, N. Y. State Mus., Bui. 65, p. 641. 

 Orthoceras (Oeisonoceras) subulatum Grabau and Shimer, 1910, N. Am. 



Index Fossils, vol. ii, p. 52, fig. 1252b. 



Description. — Shell straight, regularly enlarging from the apex nearly 

 to the aperture; transverse section circular. Living chamber well devel- 

 oped, having a length equal to about three times its diameter at the last 

 septum, regularly expanding to a point near the aperture where it is 

 slightly contracted ; air-chambers numerous, increasing in depth from the 

 apex to the outer chamber, where the depth is about 3 mm. Septa smooth 

 and thin; siphuncle small and subcentral. Test thin, surface marked by 

 very fine, irregular, lamellose striae of growth; some of the specimens 

 show longitudinal striae, and more rarely very fine, filiform, longitudinal 

 markings. The internal mould is essentially smooth, specimens from the 

 softer shales often presenting a black and polished appearance; the indi- 



