Maryland Geological Survey 695 



margins. The siphiincle is small, CA'lindrical, <and placed close beneath 

 the shell, on the peripheral margin. The test is known onl}' upon a 

 single individual, and has a thickness of about one mm. at the base of 

 the chamber of habitation. The surface is imperfectly preserved, show- 

 ing somewhat lamellose, transverse strife, with faint indications of other 

 markings. The sinus, inferring from the dirocticm of the stria% has been 

 narrow and shallow. The internal cast is essentially smooth, preserving 

 the septal margins or impressed suture lines, with impressions of the 

 fine surface striae.'' ITall, 1819. 



The thickness of the shells observed in Maryland is less than that 

 shown by Hall's figures. Diameter of largest shell observed 80 mm., 

 diameter of volution 18 mm. 



The occurrence of this representative of the Manticoceras fauna in the 

 Chemung of Maryland is of much interest. Several characteristic speci- 

 mens have been observed. 



Occurrence. — Jennings Formation, Chemung Member. Williams 

 Eoad, on Polish Mountain, 2042. Woodmont Member, Naples Fauna. 

 Woodmont. 



Collection. — Maryland Geological Survey. 



Genus PROBELOCERAS Hyatt 

 Probeloceras lutheri Clarke ( ?) 



Plate LXXII, Figs. 4, 5 



Probeloceras lutheri Clarke, 1898, 16th Rept. N. Y. State GeoL, p. 90, pi. vii, 

 figs. 1-10. 



Description. — Flattened specimens in the shales at various points are 

 referred provisionally to this species though none have yet shown the 

 chai-acteristic acutely lobed septation. These specimens are small, widely 

 umbilicated, flat and smooth shells, with distinct bands or " tire " on the 

 ventral periphery and in these respects they agree with P. lutheri. 

 Examples from the soft shales of New York are often of small size like 

 these. One of those here figured shows a portion of the actual aperture 

 of the shell, the projecting ventral elongation. 



Diameter of shell 25 mm.; diameter of volution 12 mm. 



