GASTEROPODA. 59 



This species is not rare in the Red Crag, but the specimens are generally more or 

 less rubbed. In those which are best preserved, fine impressed striae may be detected 

 between the ribs. It differs from CI. mitrula in having fewer costae, and a more elevated 

 spire ; and the ribs in this are more oblique, sloping to the left, and preserving gene- 

 rally a continuous oblique line of ridge, interrupted only by the suture ; the spaces 

 between them are rather wider than the ribs, and the first two volutions are destitute 

 of costse, but are cancellated ; the aperture varies from one third to two fifths of the 

 length of the axis. The figure does not well represent the ribs, as they slope a little 

 more towards the upper part, and incline backwards. The outer lip is sharp, with a 

 thickened obtuse varix on the exterior, and it has also a thickening upon the inside, 

 particularly near the sinus, which is rather broad. The figure by Nyst probably repre- 

 sents the same species, though my specimens are all more slender and attenuated 

 than his figure. It is, however, a doubtful identification, and he has described that 

 shell as smooth ; my Crag specimens, when perfect, are transversely striated. 



6. Clavatula mitrula. /. Sow. Tab. VII, fig. 7, 8 a. 



BucciNUM MiTRnLA. J. Sow. Min. Conch, t. 375, fig. 3, 1822. 

 Pletjrotoma mitrula. S. Wood. Catalogue 1842. 



CI. Testa turritd, elongatd, subfusiforvii, apice acuta ; anfractibus septem convexius- 

 culis, plicatis, plicis circa decern obliquis, sub lente tenuissime striatis ; striis transversis 

 impressis ; aperturd lanceolato-ovatd. 



Shell elongato-turriculate, subfusiform, costated ; whorls 7, slightly convex, orna- 

 mented with about ten obhque, obtuse, rounded ribs, and finely striated transversely, 

 with a shai'p and curved outer lip ; sinus a little below the suture. 



Axis, I of an inch. 



Locality. Cor. Crag, Sutton. 



Red Crag, Sutton and Walton Naze. 



This is an abundant species in the Red Crag. Good specimens are covered with 

 transverse impressed striae. The ribs are ver}^ slightly curved, and are rather more 

 prominent on the upper part ; they are as wide as the spaces between them, and rarely 

 in a continuous line ; the apex is sharp, and the first two volutions are without the 

 large obtuse ribs, but are cancellated. The outer lip is slightly curved and sharp ; it 

 is marginated on the outside, and thickened within, particularly below the sinus, and 

 has a deep, distinct sutui'e. The lower part of the outer lip projects slightly, with a 

 wide and rather short canal. Aperture about two fifths the length of axis. It 

 resembles in form PL multilineolatum, Phil. (t. 26, f. 1), but the whorls are more 

 convex. 



