32 SUPPLEMENT TO THE CRAG MOLLUSCA. 
PLEUROTOMA. 
The genus Plewrotoma, as originally instituted by Lamarck, was intended for those 
fusiform shells possessing a slit in the outer lip for the excurrent canal. ‘here is, 
however, a large group of this kind of shell in which the outlet varies from a deep and 
narrow incision, such as in P/. Babylonia, through a broad and sloping sinus, until it 
vanishes in the genus Fwsus. These have been divided into many genera, such as 
Mangilia, Bela, Defrancia, Clavatula, Rhaphitoma, and several more. The impossibility 
of drawing a satisfactory line between these genera seems to have induced M. Hornes, in 
his work ‘On the Vienna Fossils, to group them all under the generic name of 
Pleurotoma, and in this Supplement I have followed his example. 
PLEvROTOMA coronata ? Bellardi. Supplement, Tab. VI, fig. 4, a, 6. 
PLEUROTOMA CoRoNATA, Bellardi. Mon. Pleurot. Foss., p. 47, t. iii, fig. 5, 1847. 
Locality. Red Crag, Waldringfield. 
A single specimen from the nodule pit in the Red Crag at Waldringfield has been 
put into my hands for examination by the Rev. H. Canham. This shell has a smaller 
and shorter aperture than is shown in Bellardi’s figure of this species ; but the Crag 
specimen is unique, and I have given to it the above name provisionally. There is a 
distinct ridge on the lower part of the volution just above the suture ; the knobs are on 
a somewhat angular whorl, and the sinus is not very distinct. It is probably a derived 
specimen. 
PLEUROTOMA INTORTA, Brocchi. Crag Moll., vol. i, Tab. VI, fig. 4. 
Although some more specimens have been turned out of the nodule pits, this species 
may, I think, be still classed among the extraneous fossils of the Red Crag. I have not 
yet seen it from the Coralline Crag. It much resembles PV. callosa, Kiener, from the 
Gaboon River. 
PLEvRoTOMA InTERRUPTA, Brocchi. Supplement, Tab. V, fig. 1. 
Murex INTERRUPTUS, Broce. Conch. Foss. Subapen, t. ix, fig. 21, 1814. 
PLEUROTOMA INTERRUPTA, Bellardi. Mon. Pleurot. Foss., p. 31, t.ri, fig. 16, 1845. 
— TURRIS, Lam. Hist. des An. sans Vert., vol. vii, p. 97. 
