54 PLIOCENE MOLLUSCA. 



several more of a similar character from that place, in one of them the sinuous 

 longitudinal costfe being clearly though faintly shown. 



Terebra exilis, A. Bell. Plate II, figs. 4, 5, 



1871. Terebra exilis, A. Bell, Ann. Mag. Nat. Hist. [4], vol. vii, p. 355. 



1872. Terebra canalis. var. acuminata, S. V. Wood, Mon. Crag Moll., 1st Suppl., p. 203, tab. iv, fig. 1. 



Specific Characters. — Shell clextral, slender; apex obtuse or slightly mam- 

 millated; whorls 12 — 14, flat or but slightly convex, regularly diminishing in size; 

 upper w^horls ornamented by fine, inconspicuous and numerous longitudinal costee; 

 mouth small, oval; canal short, open, turning to the left; pillar twisted. 



Dimensions. — L. 15 — 20 mm. B. 5 — 8 mm. 



Distribution. — Not known living. 



Fossil ; Coralline Crag : Gledgrave. Waltonian : Little Oakley. 



BeniarJcs. — This shell, regarded by Wood in the synoptical list of Mollusca 

 published with his first Supplement as a variety of Terebra canalis, differs from the 

 Belgian variety costata in sculpture, and from it and the British type in its slender 

 and elongated spire ; one or two of the Oakley specimens are more slender than 

 the type, measuring 17 mm. in length and only 4 mm. in breath. This form was 

 described by Mr. A. Bell as a new species under the name of T. exilis, and I am 

 inclined to agree with him. None of these dextral shells are as common as the 

 sinistral examples, either in England or Belgium. Mr. Bell's type-specimen is in 

 the York Museum. 



Terebra inversa, Nyst, var. costata, nov. Plate II, fig. 7. 



1843. Terebra inversa, Nyst, Coq. foss Terr. Tert. Belg., p. 581, pi. xliv, fig. 9. 



1848. Terebra inversa, S. V. Wood, Mon. Crag Moll, pt. i, p. 26, tab. iv, fig. 3. 



1881. Tertbra inversa, Nyst, Conch. Terr. Tert. Belg., p. 21, pi. ii, fig. 2. 



1892. Terebra inversa. Van den Broeck, Bull. Soc. Beige Grcol , vol. vi (Meiuoires), p. 120. 



1912. Terebra inversa, Tescli, Med. v. d. Eijks. v. Delfstoffen, pt. iv, p. 86. 



Specific Characters. — See Mon. Crag Moll., pt. i, p. 26. 



Dimensions. — L. 25 — 30 mm. B. 8 — 10 mm. 



Distribution. — Not known living. 



Fossil: Coralline Crag. Red Crag — Waltonian ; Newbournian. 

 Diestien, Scaldisien and Poederlien : Belgium. Scaldisien : Holland. 



Remarks. — Wood seems to have found this species but rarely either in the 

 Coralline or the Red Crag, but I have obtained 70 or 80 specimens from the 

 Waltonian of Little Oakley. Man}^ of them are Avorn or broken as Wood's were, 

 but it does not follow that they are derivative, as they occur in fresh and perfect 



