GASTROPODA— TROCHIDJE. 



703 



323. G. glandula (Conrad). (Fig. ion, #.) Eocenic. 

 With deeply impressed suture and numerous fine spirals ; several 



angulations due to coarser spirals ; right lip toothed at base within. 

 Aquia formation, Maryland, etc. 



XCI. Calliostoma Swainson. 

 Trochoid shells, with abrupt basal deflection, peripheral keel, 

 and flattened shoulders ; surface with ribs or spirals. The urn- 

 bilicated forms are referable to Eutrochus A. Adams. Triassic- 

 Recent. 



324. C. philanthropus (Conrad). (Fig. ioii,£.) Miocenic. 

 With pronounced peripheral keel, the upper spirals beaded or 



Fig. ioii. a, Gibbula glandula, X4» ^> Calliostoma philanthiofus,y^±\ c, C. 

 eboreum, X Z% > d> C- aphelium,y^2.\ e-g, C. (Eutrochus) humdi,y^\. (After 

 Martin, Md. Survey. ) 



nodulated. Some varieties have three beaded or nodulated spirals, 

 with sometimes intercalated smaller smoother ones. 



Chesapeakean (St. Mary's, Choptank, and Calvert formations) 

 of Maryland. 



325. C. eboreum (Wagner). (Fig. ion,r.) Miocenic. 

 Mostly smooth, with faint concavity in upper part of shoulder, 



and, rarely, fine spirals, except below the obtuse keel, which is 

 seen on the body whorl. (C. aphelium Dall (Fig. ion, d) has 

 somewhat more rounded whorls and subsutural row of white spots.) 

 Choptank and Calvert formations of Maryland. 



326. C. (Eutrochus) humile (Conrad). (Fig. ion , c-g.) 



Miocenic. 

 Umbilicated, broad, low-spired ; keel faint ; spirals fine ; aper- 

 ture subrhomboidal. 



St. Mary's formation, Maryland ; common. 



