Maryland Geological Survey 405 



Avellana costata (Johnson) Weller 



Cinulia costata Johnson, 1898, Ann. Rept. Geol. Survey of New Jersey, 1897, 



p. 264 (name only). 

 Cinulia costata Johnson, 1898, Proc. Acad. Nat. Sci., Phila., p. 462, text fig. 1. 

 Cinulia costata Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 19. 

 Avellana costata Weller, 1907, Geol. Survey of New Jersey, Pal., vol. iv, 



p. 810, pi. xcix, fig. 21. 



Description. — " Shell with four whorls, spire prominent, body whorl 

 with from twelve to thirteen revolving grooves, which form an equal num- 

 ber of smooth, flat, revolving costas; these average about double the width 

 of the grooves. In one specimen the third and fifth costse from the suture 

 are almost twice the width of the others, and the two lower costse divided 

 by a minute, impressed line. The first spiral whorl has six, and the second 

 five revolving grooves. Apical whorl smooth, suture deeply impressed. 

 Aperture narrow, oblique, lip broad, thick and crenulated on the inner 

 margin with eight small teeth-like projections, and extending to the suture 

 where it joins the callus of the peristome, which is continuous to the base 

 of the columella ; base with two oblique folds, above which is a prominent 

 fold or plate extending at almost right angles to the columella ; between 

 this and the posterior angle of the aperture is a small, tooth-like projec- 

 tion. Altitude 4 mm., diameter 2 } mm." — Johnson, 1898. 



Type Locality. — Mount Laurel, New Jersey. 



Avellana costata (Johnson) is restricted in its Maryland distribution to 

 the Monmouth where it is associated with Ringicula clarM, which it 

 closely resembles in size and contour. The development of a well defined 

 though feeble spiral sculpture over the entire external surface of the 

 former readily separates it from the Ringicula, which is, to be sure, faintly 

 lineated spirally in front of the posterior suture and near the base, but not 

 at all upon the medial portion of the body. 



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

 County. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences. 



Outside Distribution. — Matawan Formation. .? Woodbury clay, New 

 Jersey. 



