136 SYSTEMATIC PALEONTOLOGY 



covered with fine crowded longitudinal lines. This species resembles 

 Retusa sulcata but is not as slender as that species. 



Length, 3.5 mm. ; diameter, 1.5 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Cornell University, U. S. National Museum. 



Eetusa (Cyliohnina) conulus (Deshayes). 

 Plate XXXIX, Fig. 11. 



JBulla conulus Deshayes, 1-624, Desc. Coquiiles Fossiles des Env. de Paris, vol. ii, p. 

 41, pi. V, figs. 34-36. 



Description. — " Testa ovato-conica, basi tenuissime striata ; columella 

 subuniplicata, apertura superne angustissima, basi dilatata; spira inclusa, 

 minime perforata. 



" Sa f orm.e conique, son ouverture tres-etroite, sa columelle marginee et 

 qui offre un pli presque complet, sa petitesse, la finesse de ses stries et 

 sa levre droite un peu sinueuse et souvent epaissie, sont de tres-bons 

 caracteres. Les plus grands individus sont longs de cinq a six milli- 

 metres et larges de deux et demi a la base." Deshayes, 1824. 



This is the first recognition of the occurrence of this widely distrib- 

 uted European Tertiary species on this side of the Atlantic. 



Length, 5 mm. ; diameter, 2 mm. 



Occurrence. — Calvert Formation. Plum Point, Church Hill, Cen- 

 treville Well at depth of 170 feet. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Cornell University, U. S. National Museum. 



Eetusa (Cylichnina) subspissa (Conrad). 

 Plate XXXIX, Fig. 12. 



Bulla subspissa Conrad, 184S, Proc. Acad. Nat. Sci. Phila., vol. lii, p. 20, pi. i, 



fig. 39. 

 Bulla subspissa Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 571. 

 Bulla subspissa Me^k, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 13. 



Description. — " Oblong-oval, thick, ventricose in the middle ; labium 

 rounded or ventricose; margin of lab rum straight above; base minutely 

 umbilicated." Conrad, 1848. 



