168 SYSTEMATIC PALEONTOLOGY 



constricted at the suture, and in having smaller and more distant 

 longitudinal ribs. 



The only specimen has been badly broken, so no attempt is made to 

 name or illustrate the species. 



Length, 7 mm. ; diameter, 3 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — Maryland Geological Survey. 



Subgenus CANCELLARIELLA n. sub-g. 



Shell small, depressed, Nerita-like. Mouth strongly canaliculate, 

 with a deep anterior siphonal notch. Columella concave, with four 

 plaits, of which there are two close together at the base, the upper 

 being the strongest, one still stronger at the middle of the columella 

 and one at the top which does not extend far in. Between the two 

 middle ones is a deep concavity which, within, becomes a deep furrow 

 overhung by the plaits. Back from the mouth all but the two medial 

 plaits become obsolete. Umbilicus broad and prominent. Spire much 

 depressed. 



Type Cancellaria (CanceUarieUa) neritoidea Martin. 



No other species has come to my notice which would fall in this 

 subgenus. 



Cancellaria (Cancellariella) neritoidea n. sp. 

 Plate XLIII, Figs. 13a, 13b. 



Description. — Whorls three; body whorl very large in proportion to 

 the size of the shell; spire depressed; ornamentation consists of about 

 twenty broad, impressed, revolving lines with broader, gently arched 

 interspaces; lines of growth prominent; surface wrinkled by irregular 

 varix-like undulations which are most prominent toward the suture; 

 suture deeply impressed; ornamentation of the spire entirely destroyed 

 if any ever existed; umbilicus long, crescent shaped, strongly wrinkled 

 by lines of growth: mouth broadly subovate, and wider below than 

 above; notch for the anterior canal \ery deep. 



Length, 8 mm.; width, 8 mm. 



Occurrence. — Choptank Formation. Jones Wharf. 



Collection. — Maryland Geological Survey. 



