452 PLIOCENE MOLLUSCA. 



latter group. It has been described by those who have written on the subject 

 as identical with T. triplicata, but the sculpture as well as the form of these two is 

 essentially different, and they do not appear to have any near relationship. It is 

 equally difficult, I suggest, to regard our shell as a variety of T. incrasmta. It 

 occurs only, but very abundantly at St. Erth, and many specimens of it are to be 

 found in our public collections, as, for example, in the Sedgwick Museum at 

 Cambridge. They are all of the same type, agreeing with each other, but, so 

 far as I know, with nothing else that has been hitherto described. It may be 

 desirable, therefore, I think, to consider them specifically distinct. 



Turritella (Haustator) crenulata (Nyst). Plate XLII, figs. 18, 19. 



1843. Turritella crenulata, Nyst, Coq. foss. Terr, terfc. Belg., p. 399, pi. xxxvii, fig. 6. 

 1874. Turritella crenulata, Van den Broeck, Ann. Soc. Roy. Malac. Belg., vol. ix, p. 157. 

 1912. Turritella (Haustator) crenulata, Cossmann, Ess. Paleoconch. compar., vol. ix, p. 118. 



Specific Characters. — Shell of moderate size, elongate, turreted ; whorls convex; 

 suture deep ; ornamented by 6 or 7 spiral ridges, equal and equidistant ; base 

 rounded. 



Dimensions. — L. 20 — 25 mm. B. 5— G mm. 



Distribution. — Not known livinsr. 



Fossil : Walton i an Crag : Little Oakley. 



Oligocene : Belgium — Vliermael, Hoesselt, Bolderberg. 



Pliocene (Diestien) : Belgium. 



Remarks. — I have one or two imperfect specimens in my collection from Oakley 

 which appear to correspond with some specimens of T. crenulata, Nyst, in the 

 Sedgwick Museum, received some years ago under that name from the Royal 

 Museum of Natural History at Brussels, of which Nyst was then the Director. 

 They do not altogether correspond with the specimen given by the latter in 1843, 

 but my experience of the last few years has shown me that the pre-photograpliic 

 figures of the earlier writers are not always to be relied on. Our shell may be 

 probably derivative in the Crag. 



Turritella (Haustator) marginalis (Brocchi). Plate XLIII, figs. 9 — 11. 



1814. Turbo marginalis, Brocchi, Conch, foss. subap , vol. ii, p. 373, pi. vi, fig. 20. 



1832-40. Turritella marginalis, Grateloup, Actes Soc. Linn. Bordeaux, vol. v, p. 165, no. 245, 1832 ; 



Atlas (Turritella), pi. i, fig. 11, 1840. 

 (?) 1856. Turritella marginalis, Homes, Foss. Moll. Tert. Wieu, vol. i, p. 428, pi. xliii, fig. 4. 

 1882. Turritella marginalis, von Koenen, Nord-deutsch. Miocitn, Moll.-faun., vol. ii, p. 286, no. 191. 

 1886. Turritella (Haustator) marginalis, Dollfus et Dautzenberg, Feuilles des jeunes Nat,, vol. xvi, 



p. 138. 

 1890-5. Turritella marginalis and vars., Sacco, Boll. Soc. Geol. Ital., vol. ix, p. 3:24, no. 5319, 1890; 



Haustator marginalis, Moll. Terr. Terz. Piem., pt. xix, p. 16, pi. i, fig. 55, 1895. 



