310 Systematic Paleontology — Middle Devonian 



times becoming a very conspicuous feature; air-chambers numerous, 

 regular, with, a depth of from two to three mm. Septa smooth and thin; 

 sutures straight and horizontal; siphuncle central. Test not preserved 

 but some of the impressions show traces of lamellose striae of growth ; the 

 internal impression of the chambers is smooth, with the sutures but little 

 impressed. This species is distinguished from 0. svhulatum by its con- 

 stricted and much more developed chamber of habitation ; in the depth of 

 the air-chambers and the position of the siphuncle the two species are very 

 similar ; it is further removed from 0. exile by the depth of the air-cham- 

 bers and its central siphuncle. 



This species is represented in the [Maryland Collection by a single 

 fragment of a living chamber from the Oldtown Eoad near Cumberland ; 

 but the characteristic constriction is well shown and there is apparently 

 no question but that it belongs to this species. Hall also reported the 

 species at Cumberland, Md.* Later, additional specimens were obtained 

 from other localities. 



Length of the preserved part of the chamber of habitation, 38 mm.; 

 width, about 19 mm. 



Occurrence. — Romney roRMATiON, Hamilton Member. Oldtown 

 Eoad near Cumberland; east bank Evitts Creek below Wolfe Mill (?) ; 

 on Oldtown Eoad east of Maryland Ave., Cumberland; on road 1 mile 

 north of Romney, W. Ya. ( ?) ; W. Va. side Potomac Eiver about 3 miles 

 south of Cumberland. 



Collections. — Maryland Geological Survey; New York State Museum; 

 American Museum of Natural History. 



Orthoceras cf. exile Hall 

 Plate XXXIX, Fig. 9 



Orthoceras exile Hall, 1861, Desc. New Species of Fossils, etc., p. 50. 

 Orthoceras exile Hall, 18G2, Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 78. 



pi. viii, fig. 5. 

 Orthoceras exile Hall. 1879, Pal. N. Y., vol. v, pt. ii, p. 290, pi. xxxix, fig. 3; 



pL Ixxxiv, fig. 3; pi. Ixxxv, figs. 1, 2, 14, 15. 

 Orthoceras exile Keyes, 1891, Johns Hopkins Univ. Circ, vol. xi, p. 29. 



' Pal. N. Y., vol. v, pt. ii, p. 289. 



