Maryland Geological Survey 419 



terminate and nuclear characters are lost; external sculpture rather sub- 

 dued ; axials eight or nine in number on the later volutions, rather broad, 

 rounded, and moderately elevated upon the earlier turns, but becoming 

 increasingly broader, lower, and more undulatory, and on the body whorl, 

 manifested chiefly as a regularly crenulated shoulder carina; fasciole 

 nodulated, the nodes unusually regular in size and spacing and approxi- 

 mately double the number of the costa? ; spiral sculpture restricted to the 

 base of the ultima and the pillar, with the exception of very faint and 

 irregular stria? which, when intersected by the equally faint incremental?, 

 give to the surface a very finely cancellated aspect; base of the body 

 lirated with four quite prominent spirals separated by slightly wider inter- 

 spirals; pillar sculpture becoming increasingly finer and more crowded 

 toward its anterior extremity; fasciole rather narrow, closely appressed, 

 margined posteriorly by the impressed suture and anteriorly by a well 

 defined sulcus, smooth excepting for the nodules; body whorl flattened, 

 quite abruptly constricted at the base; aperture narrow, spatulate; 

 siphonal notch, as deduced from the growth lines placed directly in front 

 of the fasciole ; outer lip thin, sharp, arcuate ; inner lip smoothly concave ; 

 pillar long and straight with subparallel margins. 



Dimensions (imperfect individual). — Altitude 47 mm., maximum 

 diameter 17 mm. 



This species is well characterized by its flattened whorls, rather feeble 

 axial sculpture and the absence of macroscopic spiral structure, excepting 

 upon the base of the body and the pillar. 



Occurrence. — Monmouth Formation. Brightseat, Prince George's 

 County, 



Collection. — Maryland Geological Survey. 



Genus SURCULA H. and A Adams 

 [Genera of Recent Mollusca, vol. i, 1853, p. 88] 

 Type. — Pleurotoma javana Linne. 



Surcula differs from Tunis in the characters of the operculum, the 

 closer proximity of the siphonal notch to the posterior suture, and the 

 tendency, in many individuals, toward a recurved anterior canal. 



Etymology: Surculus, a sprout. 



