28 SUPPLEMENT TO THE CRAG MOLLUSCA. 



correct. The peculiar ornamentation of the upper volutions is spoken of in the ' Brit. 

 Moll.,' as also in ' Brit. Conch.,' but it has never been represented. 



Trophon muricatus. Crag Moll., vol. i, Tab. VI, fig. 5. 



A perfect specimen has occurred in the Middle Glacial sand of Billockby, but I have 

 not met with it from the Eluvio-marine Crag, the Chillesford bed, or from the Lower 

 Glacial sands. 



Trophon mediglacialis, S. Wood. Supplement, Tab. VII, fig. 12, a, b. 



Spec. Char. T. Testa elongato-fusiformi, anfractibus rotundatis, longitudinalifer 

 costatd, costis (8 — 10) elevatis obtusis ; spiraliter lineatd, lineis paucis elevatis ; aperturd 

 ovatd ; caudd elongatd. 



Locality. Middle Glacial, Billockby, and Hopton. 



Length, half an inch nearly. 



About a dozen specimens of this shell have occurred in the Middle Glacial sand of 

 Billockby, and five in that of Hoptcn, and as they do not vary greatly in size, I infer 

 that the specimen figured is a full-grown shell, or nearly so. Like almost all the fossils 

 from this formation, the specimens are in a more or less injured condition ; but the one 

 figured has suffered but little, as the spiral striae are preserved on it. The upper part of 

 the whorls do not show any spiral striation, and this appears, not only in the specimen 

 figured, but on such others as retain the external markings. As all the specmens, however, 

 are more or less worn, this absence of striata on the upper part of the whorl may possibly 

 be due to erosion. The costae appear to be nearly equal in number on all the volutions. 

 None of the specimens indicate any less tapering form than that figured, while some are 

 slightly more tapering and slender. 



This species being unknown to me from any other formation than the Middle Glacial 

 sand of East Anglia, while it is somewhat numerous there, it appears to be characteristic 

 of that formation ; I have therefore assigned to it the specific name of mediglacialis. 



Trophon? Billockbiknsis, S. Wood. Supplement, Tab. VII, fig. 13. 



Locality. Middle Glacial, Billockby. 



Length, \ of an inch. 



A unique specimen in good preservation from Billockby, shown in fig. 13, is the 

 foundation for this species, but whether it be a young specimen or a full-grown shell, 

 there are no means of judging. It differs from mediglacialis in its less tapering form, 



