1917.] NATURAL SCIENCES OF PHILADELPHIA. 281 



shouldered or strongly tabulated, the maximum diameter falling in 

 front of the median horizontal, volutions closely appressed and 

 increasing gradually in size, probably four in number in a perfect 

 individual; sculpture subdued and irregular; well-defined axial costse 

 not developed; spirals low and crowded, about six in number on the 

 penultima, and more than sixteen on the ultima, spirals crossed by 

 numerous irregular, sharply incised incremental lines which give the 

 surface of the shell a subcancellate aspect; suture impressed; body 

 shouldered posteriorly and sloping gently and evenly in front; 

 aperture narrow; margin of outer lip broken away; inner lip concave 

 medially; columella slightly flexed near the anterior extremity; 

 umbilicus indicated by a narrow depression along the outer margin 

 of the reflected inner lip. 



Dimensions. — Altitude 4.3 mm.; maximum diameter 2.5 mm. 



This form is represented by a single specimen. The species has 

 been referred to the genus Conorbis since it shows all the generic 

 features revealed in the type of the genus, Conus dormitor (Sowerby) * 

 from the Eocene of western Europe. The Tennessee form is probably 

 the first typical Conorbis to be reported from the Upper Cretaceous. 

 An imperfect individual from the Senonian of Ria Piabas, Brazil, 

 has been described under the name of Conorbis restitutus,^ but the 

 correctness of this generic determination has been questioned by 

 Cossmann.^ 



Family VOLUTIDJE. 



Genus HYLLUS n. gen. 



Etymology: Hyllus, a son of Hercules. 



Type: Hyllus callilateras n. sp. 



Shell large and subovoid in outline; spire obtuse or only slightly 

 elevated; whorls closely appressed, increasing in size rapidly to a 

 much inflated body; protoconch unknown; sculpture absent, external 

 surface free from ornamentation except for incremental lines which 

 show through the glazed surface; sutures obscured by callus; body 

 slightly inflated and sometimes flattened dorso-ventrally, gently 

 constricted behind, and in front it slopes gradually into a 

 broad, slightly curved short pillar; aperture broad and lenticular, 

 distinctly notched in front or produced into a short canal, slightly 

 notched posteriorly; outer lip simple and broadly arcuate; inner lip 



* Cossmann, M., 1896, Ess. de Pal. Comp., livr. II, p. 149, PI. VIII, figs. 16 et 18,. 

 ^ Wliite, C. A., 1888, Archiv de Museu Nacionale de Rio de Janeiro, vol. VII.. 

 p. 119, est. X, figs. 4, 5. 



^ Cossmann, M., loc. cit., p. 1.50. 



