﻿LITTORINA. 187 



bounded by a short groove immediately behind the suture, followed first by a row 

 of large indistinct distant tubercles ; then, after a wide interval, by a row of 

 closer and clearer longitudinal tubercles ; then, after a less interval, at the widest 

 part of the shell by another row which has almost become linear; and then, after 

 a similar interval, by six small close linear ridges, only made nodulous by the growth- 

 lines, and gradually becoming indistinct and vanishing in front, so that the lower 

 third of the whorl has no other marks but the growth-lines. Upper whorls having 

 only the first three of the above-described nodulous growths exposed, which have, 

 moreover, become less nodulous as they have decreased in size. Mouth pear- 

 shaped, entire, sharply pointed behind, rounded in front, edentulous ; outer lip 

 gently convex, sharp ; inner lip slightly diffuse, rather convex on the side of the 

 aperture, flattened and thickened as it curves round the front of the mouth. 

 Shell-structure very thick. No umbilicus. v 



Size. — Height 17 mm., transverse diameter 14 mm. 



Locality. — Chudleigh. There are nine specimens in Mr. Vicary's Collection. 



Remarks. — It is rarely that we find Devonian Gasteropods in so fine a state 

 of preservation as are these little shells. They are entirely free from matrix, and 

 some of them are so lifelike that it is difficult to separate at a glance a small 

 recent shell which Mr. Vicary has purposely placed in the tray which contains 

 them. There appears to be some small degree of variability in the different 

 individuals, especially in regard to the length of the spire, but the species is, 

 upon the whole, exceedingly well marked. 



This species appears to have all the characters of the genus Littorina as far as 

 the shell is concerned, and I have therefore placed it under that genus, although, 

 according to Zittel, it has not been established below the Chalk. On my showing 

 a specimen of it to Mr. E. A. Smith he independently referred it to the same genus. 

 It is evidently closely allied to, and belongs to the same genus as, the shell 

 which is next to be described. 



Affinities. — Natica margaritifera, d'Arch. and de Vera., 1 is more globose, has 

 a shorter spire, and its ornamentation is uniform all over the whorl. 



Trochus quinquecinctus, Goldfuss, 2 seems almost exactly to correspond in its 

 markings, but it appears to differ generically as well as specifically, being a 

 shorter, less fusiform shell, with a flatter, broader base, a more circular mouth, 

 and a distinct though small umbilicus. 



Turbo arw.atus, Goldfuss 3 and Romer, 4 is very similar, but it has a much more 

 elevated spire, a smaller body-whorl, a smaller mouth, and coarser ornamentation. 



1 1842, d'Arch. and de Vern., ' Geol. Trans.,' ser. 2, vol. vi, pt. 2, pi. xxxiv, figs. 4, 4 a. 



2 1844, Goldf., ' Petref.,' vol. iii, p. 48, pi. clxxviii, figs. 3 a, b. 



3 1844, ibid., p. 89, pi. cxcii, figs. 2 a — c, and pi. cxciii, fig. 17. 

 * 1876, F. Eomer, ' Leth. Pal.,' pi. xxxii, fig. 5. 



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