18 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



Geological Position and Locality. The Great Oolite of Stonesfield, collected by Mr. 

 Whiteaves. 



RISSOINA WITCHELLI, Lye. Tab. XL1V, fig. 12. 



Testa elongato-turrita, anfractibus 6, latis, convexis, aut media angulatis, longitudinaliter 

 costellatis, costellis circa 26 28, rectis, simplicibus, crebris ; apertura ovato-obliqua, labro 

 extus incrassato. 



Shell elongately turreted ; volutions 6, wide, convex, angulated at their middle part, 

 and encircled with a slender band at the mesial angle ; the longitudinal little ribs are very 

 closely arranged ; they are smooth, narrow, perpendicular, and are united to the mesial 

 band ; from 26 to 28 in a volution ; the last volution is conformable with the others, both 

 in figure and ornamentation ; the aperture is of moderate size, it is oblique, ovate, but 

 rather pointed at the two extremities ; the columella is curved in its middle ; the outer lip 

 is thickened. 



The angulated figure approximates to Rissoina duplicata, Sow., sp., ' Gr. Ool. Mon./ 

 i, p. 52) ; but the last volution is somewhat less expanded, the costse upon the spire are 

 less conspicuous, and nearly three times as numerous. Mr. Witchell, who discovered the 

 species, has kindly communicated several specimens which agree with each other in all 

 essential particulars. 



Geological Position and Locality. The Great Oolite of Minchinhampton Common, 

 associated with other minute testacea. 



RISSOINA MILLERI, Lye. Tab. XL1V, fig. 10. 



Tesia turrita subcylindrica, anfractibus (6) subconvexis, angustis, longitudinalitcr costel- 

 latis; costellis 17 18, rectis simplicibus; apertura ovato-semilunari, ad basim rffttsa ; 

 labro extus valde incrassato. 



Shell turreted, subcylindrical ; volutions (6) convex in their middle part, narrow, but 

 with the sutures only slightly impressed ; longitudinally costellated; costellas 17 18, per- 

 pendicular, not very prominent, and plain ; aperture ovately semilunar, oblique, expanded 

 at the base, the outer lip having a considerable thickening. 



Allied to Rissoina acuta, Sow., but having the volutions more narrow and less con- 

 vex, the sutures being less deeply impressed ; the little ribs are much more numerous ; 

 the aperture is also larger and more effuse at the base. 



Geological Position and Locality. One of a series of minute univalves obtained by 

 Mr. Whiteaves in the Great Oolite of Minehinhampton Common. The name is an 

 acknowledgment of the discrimination of the author of ' The Natural History of the Crin- 

 uoidea,' who appears to have been the first person to discover the fossil riches of this locality, 



