32 SUPPLEMENT TO THE CRAG MOLLUSCA. 



Pleurotoma. 



The genus Pleurotoma, as originally instituted by Lamarck, was intended for those 

 fusiform shells possessing a slit in the outer lip for the excurrent canal. There is, 

 however, a large group of this kind of shell in which the outlet varies from a deep and 

 narrow incision, such as in PI. Babylonia, through a broad and sloping sinus, until it 

 vanishes in the genus Fusus. These have been divided into many genera, such as 

 Mangilia, Beta, Defrancia, Clavatula, Bhaphitoma, and several more. The impossibility 

 of drawing a satisfactory line between these genera seems to have induced M. Homes, 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. 



Pleurotoma coronata ? Bellardi. Supplement, Tab. VI, fig. 4, a, b. 



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 PI. callosa, Kiener, from the 

 Gaboon River. 



Pleurotoma interrupta, Brocchi. Supplement, Tab. V, fig. 1. 



Murex interrupts, Broc. Conch. Foss. Subapen, t. ix, fig. 21, 1814. 

 Pleurotoma interrupta, Bellardi. Mon. Pleurot. Foss., p. 31, t. i, fig. 16, 1845. 

 — tdrris, Lam. Hist, des An. sans Vert., vol. vii, p. 97. 



