82 MOLLUSCA FROM THE GREAT OOLITE. 



TROCHOTOMA ACUMINATA, Deal. Plate X, figs. 180, 20. 



TKOCHOTOMA ACUMINATA, Deslongchamps. 1842. M6m. Soc. Linn, de Normandie, 



torn, vii, p. 108, pi. 8, figs. 1115. 

 DITEEMAEIA ACUMINATA, If Orb. 1850, Prod. Pal6ont., p. 301. 



T. Testa conicd, spird plus minusve elatd, lavi aut substriatd; apice acuminato ; 

 anfractibus (7, 8) ex apice ad aperturam magis d magis tumescentibus donee ultimus sub- 

 quadratus fiat ; infond facie dilatatd, in medio cavum infunbibuliformem ferente, ad peri- 

 phaeriam concentrice striatd. (Deslongchamps.) 



Shell conical, spire more or less elevated, smooth, or slightly striated ; apex acute ; 

 whorls (7, 8) gradually increasing from the apex until the last whorl becomes subquadrate ; 

 the lower surface has a very deep but somewhat contracted cavity, which is concentrically 

 striated. 



This is the most elevated or conical of the Great Oolite species. The last volution is 

 distinctly striated, the rib posterior to the aperture being very prominent ; the height and 

 basal diameter are about equal. 



Locality. Great Oolite of Minchinhampton and Bussage ; Langrune, France. 



TROCHOTOMA CONULOIDES, Desl. Plate X, fig. 16. 



TROCHOTOMA CONULOTDES, Deslongchamps. 1842. Mem. Soc. Linn, de Normandie, 



torn. Yii, p. 109, pi. 8, figs. 1619. 

 DITEEMARIA D'Orb. Prod. Pal&mt., p. 301 . 



T. Testa conicd, apice acuto; anfractibus (5, 6) concentrice striatis, planis ; ultimo 

 anfractu vix ad fasuram dilatato ; basi ad peripheeriam convexiusculd, striatd, in medio 

 profunde excavatd. 



Shell regularly conical, apex acute ; whorls (5, 6) concentrically striated, flattened ; 

 the lower surface convex, striated, and deeply excavated. 



The volutions are narrow and flattened, the encircling rib narrow and elevated ; the 

 figure is very oblique, the basal diameter exceeds the height by one fourth. 



Our figure is somewhat reduced. 



Locality. Great Oolite of Minchinhampton and Bussage ; Luc, Langrune, France. 



