GASTEROPODA. 17 



Locality. The planking of Minchinhampton Common and white stone of Bussagc 

 contain it ; but at the latter place the more delicate features are usually best preserved. It 

 is rather rare. Inf. Oolite, Bayeux ; Great Oolite, Ranville, Normandy. {Desl.) 



Alaria laevigata. Plate III, fig. 3, Za. 



A. Testa fusiformi, anfractibus convexis, lavigatis, ultimo bicarinato, carina superiori 

 spinigera ; spino oblongo ori opposito; aid brevissimd in estate juniori monodactyld, dein 

 (estate adulta) magna didactyld, digitis longis divaricatis, tenuibus, trigonis; caudd longd, 

 recta, apice sub-incurvoj aperturd oblongd, labro sinistro subcalloso. 



Shell fusiform, whorls convex, smooth, the last whorl with two carinas, the upper carina 

 spined ; the spine oblong, and placed opposite to the aperture ; the wing very small when 

 young, at first it has but one digitation, with advance of growth it acquires two large digi- 

 tations, which diverge in opposite directions, they are smooth and three-sided ; the caudal 

 extremity is long and curved towards the apex ; the aperture is oblong, the left lip being 

 slightly thickened. 



In everything, excepting its smooth surface, this shell agrees with the Bostellaria 

 myurus of Deslongchamps ; but as we have seen about twelve specimens, which were well 

 preserved, it is impossible that they ever could have had the striae which distinguish the 

 shell from Normandy. 



Locality. It is rare, and has been found only in the planking of Minchinhampton 

 Common and contemporaneous beds of white stone north of the Vale of Brimscombe. 



Alaria hamulus, Desl. sp. Plate III, figs. 4, 4a, 4<b. 



Rostellaria HAMULUS, Deslongchamps. Mem. Soc. Linn. Normandie, vol. vii, p. 1/5, 

 pi. 9, figs. 37—40. 

 — — Desk. Lam. An. sans Vert., 1843, torn. 9, p. 666. 



Pterocera hamulus, If Orb. Prod. Paleont., p. 302. 



A. Testa parvd turritd, apice obtuso, anfractibus (5—6) carinatis nodulosis; ultimo anfractu 

 mbgibbo, transverse striato ; striis incequalibus, majoribus alternatim minoribusque ; carina 

 nodulosd seu plicatd; labro externo incrassato variculam simidante; aid parvd unidigitato, 

 apice acuto trigono, subtus canaliculato; caudd brevissimd, aperturd subellipticd. 



Shell small, turrited, clavate, apex obtuse, whorls (5 — 6) convex, nodulated, nodules 

 six in a volution. The last whorl has a single nodulated carina terminating anteriorly in a 

 slight digitation. In the immature state the digitation is produced into a hook-shaped 

 process. The surface has numerous encircling stria?, somewhat irregular, but which are 

 alternately large and small. The upper margin of each whorl has a prominent line closely 

 tuberculated ; the aperture is narrow, being contracted on the right side by a thickened 



