Maryland Geological Survey 403 



Genus AVELLANA D'Oibigny 

 [Pal. Franc, Terr. Cret., t. ii, Gastropodes, 1842, pp. 131, 132] 



Type. — Avellana incrassata Mantell. 



" Shell globose, ventricose, low, sculptured with spiral striations or 

 punctate grooves. Spire very short, aperture semi-lunar, compressed and 

 arcuate without an anterior emargination. Lip very thick, often reflected 

 and prominent without, almost always dentate within. Columellar mar- 

 gin furnished with three or four teeth, the anterior of which is the 

 strongest." — Translated from d'Orbigny, 1842. 



The genus differs from Ringicula in the development of a well defined 

 spiral sculpture, the number and disposition of the columellar plaits and 

 in the entire absence of an anterior canal. 



Arellano, has a wide distribution in strata of Cretaceous age, but it has 

 not been reported either from the older Mesozoic or from the Tertiaries. 



A. Altitude of adult shell exceeding 18 mm Avellana bullata 



B. Altitude of adult shell not exceeding 18 mm. 



1. Diameter of adult shell less than two-thirds of its altitude. 



Avellana costata 



2. Diameter of adult shell more than two-thirds of its altitude. 



a. Spirals on body whorl exceeding 15 in number. .Avellana pinguis 



b. Spirals on body whorl not exceeding 15 in number. 



Avellana lintoni 



Avellana bullata (Morton) Whitfield 



Tornitella f bullata Morton, 1834, Syn. Org. Rem. Cret. Group, U. S., p. 48, 



pi. v, fig. 3. 

 Solidula ? bullata Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 17. 

 Solidula bullata Conrad, 1868, Cook's Geol. of New Jersey, p. 728. 

 Avellana bullata Whitfield, 1892, Mon. U. S. Geol. Survey, vol. xviii, p. 163, 



pi. xx, figs. 1-4. 

 Avellana bullata Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 19. 

 Avellana bullata Weller, 1907, Geol. Survey of New Jersey, vol. iv, p. 80S, 



pi. xcix, figs. 9-11. 



Description. — " Ovoidal, ventricose. with numerous transverse stria?. 

 Length, about 1 in." — Morton, 1834. 

 Type Locality. — New Jersey. 



Etymology: Avellana, filbert. 



