﻿NATICA. 195 



widely from Phillips's type. It has much finer and more numerous striae, and is 

 more depressed, and so is very similar to the present shell. Though the striae 

 are visible on Romer' s small figure, and are therefore represented as decidedly 

 coarser than in ours, Mr. Roberts agree with me in thinking that this may be due 

 to the necessities of the drawing, and therefore that it may perhaps be intended 

 for the present species. Romer, however, mentions shorter swellings between the 

 main ribs, and, if they exist, it is unlikely to be a synonym of this shell. 



In my Collection is a fragment from Lummaton which consists of a single 

 defective whorl marked in a similar manner. It more probably, however, be- 

 longs to a Holopella, or even to a Goniatite, than to a Natica. 



Affinities. — This species differs from Natica nexicosta, Phillips, in having much 

 finer, closer, and more regular ribs, which never show any tendency to divaricate, 

 and in being less elongate. 



Natica striolata, F. A. Romer, 1 and N. spirata, F. A. Romer, 2 are more ovate 

 and elongate forms. 



Naticopsis ehgantula, (Ehlert and Davoust, 3 is almost exactly similar in shape 

 and longitudinal striation, but differs in being covered with microscopic spiral 

 lines. 



Natica infiata, F. A. Romer 4 and Tietze, 5 which is similarly striated, is a less 

 oblique shell, and has a higher spire. 



Natica modesta, " Barrande MS.," as given by Maurer, 6 approximates it in 

 shape, but is described as smooth. 



Natica Adorfensis, Holzapfel, 7 appears to be distinguished by possessing coarser 

 striae. 



Ampullaria Ponti, Goldfuss, 8 is another shell which nearly corresponds, but is 

 differentiated by having its striae less oblique, and by possessing a few coarse 

 folds immediately below the suture-line. 



1 1850, F. A. Komer, ' Beitr.,' pt. 1, p. 33, pi. v, figs. 7 a, b. 



2 Ibid., p. 34, pi. v, fig. 10. 



3 1880, (Ehlert and Davoust, 'Bull. Soc. Geol. Fr.,' ser. 3, vol. vii, p. 712, pi. xv, figs. 3, 3 a—c. 



4 1843, F. A. Eomer, 'Harz.,' p. 27, pi. vii, fig. 8. 



5 1872, Tietze, 'Dev. Schicht. Ebersdorf,' p. 40, pi. ii, fig. 26. 



6 1880, Maurer, ' Neues Jahrb. f. Min.,' Beil.-Band i, p. 32, pi. ii, fig. 13. 



7 1882, Holzapfel, ' Palaeontographica,' vol. xxviii, p. 250. 



8 1844, Groldf., ' Petref. Germ.,' vol. iii, p. 114, pi. cxcviii, figs. 17 a, b. 



2G 



