96 ME. H. WOODS ON THE MOLLUSCA [Feb. 1896, 



of four or five whorls ; outer lip thickened, with the inner margin 

 coarsely crenulated. Columella with two or three strong folds. 

 Ornamentation consisting of fine spiral grooves (about 24 on the 

 last whorl) with pits in the grooves. Size of an average specimen — 

 height 18 mm., height of last whorl 16 mm., diameter 14 mm. 



Remarks. — A. Archiaciana is found in the Aachen Greensand ; 

 the Chalk Eock species is very near to this, but without seeing 

 specimens of the Aachen form I cannot be quite sure of their 

 identity. Most of the specimens from the Chalk Hock are in the 

 form of casts, but a few have part of the shell preserved ; the 

 character of the ornamentation is seen in the wax models taken 

 from the external casts. 



Distribution. — Chalk Eock of Winchester, Cuckhamsley, Luton 

 cutting, Hitchin, and Underwood Hall near Dullingham. 



In addition to the species described above there are a few others 

 which are too imperfect for determination. 1 The most interesting 

 of these is one which belongs to the Volutidse or Mitridse ; it is 

 represented by four imperfect casts from Cuckhamsley (Montagu 

 Smith Collection) and one from Hitchin (coll. Mr. W. Hill). There 

 are three well-marked folds on the columella ; the spire of the shell 

 was long. Length of the two last whorls 27 mm., width 10 mm. 



IY. Class SCAPHOPODA. 

 Family Dentaliidse, Gray. 

 Genus Dentalitjm, Linnaeus, 1758. 

 Dentalittm tukoniense, sp. nov. (PI. IV. figs. 16 & 17.) 



Description. — Shell slender, elongate, tapering very gradually, 

 circular in section. Ornamentation consisting of twenty-five to 

 twenty-eight straight longitudinal ribs, crossed by smaller trans- 

 verse ribs. Length about 47 mm. 



Affinities. — D. planicostatum, Hebert, 2 from Meudon, is similar to 

 this species, but is distinguished by the absence of transverse ribs 

 and by the more rapid tapering of the shell. 



Distribution. — Chalk Eock of Winchester, Cuckhamsley, and 

 Luton cutting. 



1 Solarium has been recorded from the Chalk Rock, but I have seen no ex- 

 ample of this genus ; the determinations were probably based on the internal 

 casts of Pleurotomaria. 



2 Mem. Soc. geol. France, ser. 2, vol. v. (1855) p. 374, pi. xxix. f. 11. 



