40) SUPPLEMENT TO THE CRAG MOLLUSCA. 
Pievrotoma RoBusta, S. Wood. Supplement, Tab. III, fig. 16. 
Spec. Char. Pl. Testa ovato-fusiform ; anfractibus 6, juata suturam subangulatis, 
longitudinaliter costulata, obsoleté clathrata. 
Length, #ths inch. 
Locality. Upper Glacial, Bridlington. 
From a specimen in my own possession, given to me some years ago by Mr. Leckenby. 
This is the largest species of that section of this genus, to which the generic name of Mangelia 
hhas been applied, that I have met with. ‘The shell differs altogether from turricula in its 
more robust form, in its greater size, and in the indistinctness of the shoulder angle. 
PLEUROTOMA TURRICULA, Mont. Crag Moll., vol. i, p- 62, Tab. VII, fig. 13 ; Supplement, 
Tab. VII, fig. 8. 
Localities. Red Crag, Walton, Sutton, and Butley. Fluvio-marine Crag, Bramerton. 
Chillesford Bed, Aldeby. Middle Glacial, Hopton. Upper Glacial, Bridlington (/Wood- 
ward). Post-glacial, March and Kelsea Hill. ; 
Several specimens of this well-marked and common British shell have occurred in the 
Middle Glacial Sand of Billockby and Hopton, and I have a good suite of them from the 
March gravel. It is rare in the Fluvio-marine Crag, and has occurred in the Chillesford 
bed at Aldeby, and it is given as common at Kelsea Hill by Mr. Jeffreys. 
The specimen in Supplement, Tab. VII, fig. 8, is from the Middle Glacial Sand of 
Hopton Chiff. It differs from the typical form of twrricula (of which several individuals 
have been obtained from the same sand) in the relatively greater proportion of the 
body whorl, which is fully two thirds the length of the whole shell. As this, however, 
seems to me only such a modification as might be expected to occur to a chance individual, 
I have only ventured to regard it as a variety of P/. turricula. 
Pievurotoma assimiLis, S. Wood. Supplement, Tab. VI, fig. 18. 
Localities. Red Crag, Butley. Middle Glacial, Billockby and Hopton. 
Spec. Char. Pl. Testa ovato-fusiformi, obsolete clathrata ; longitudinaliter costulata 
anfractibus sex, juata suturam rotundato-angulatis ; spira acuminata. 
Length, 7ths of an inch. 
The specimen figured is from the Middle Glacial Sand at Billockby, and another has 
occurred at Hopton. I have also found in the Red Crag of Butley a specimen of it quite 
perfect, and of similar size to that figured, which, so far as I know, is unique in the Crag. 
