﻿202 DEVONIAN FAUNA. 



Some, though not all, of the figures given by Hall 1 of Platyostoma lineatum, 

 Conrad, 2 bear considerable resemblance to the present species. There is the same 

 variability of shape, but it appears to be upon the whole a flatter form, with 

 generally a less elevated spire, and the character of its ornament is totally 

 different. 



3. Platyostoma speciosum, Sowerby, sp. PI. XXIII, figs. 6, 6 a. 



1840. Nekita speciosa, Sowerby. Geol. Trans., ser. 2, vol. v, pt. 3, pi. lvii, 



fig. 15. 

 1854. — Morris. Cat. Brit. Foss., p. 264. 



Description. — Shell small, lenticular, dilate, of rather few whorls. Spire very 

 broadly conical, almost flat externally, but somewhat elevated in the centre. 

 Apex apparently sharp. Suture small but deep. Body-whorl spreading out 

 horizontally from the suture to the shoulder, where, after slightly sinking, it turns 

 through a sharpish angle, and proceeds obliquely inwards to form the base. 

 Umbilicus closed. Mouth large, trapezoidal, somewhat produced below. Lips 

 meeting in front at an obtuse angle. Inner lip much arched. 



Size. — Height 6 mm., width 12 mm. 



Locality. — A specimen in the Torquay Museum probably comes from Lumma- 

 ton or Barton. A specimen from Wolborough in the Museum of Practical 

 Geology belongs either to this species or to Euomphalus circularis. 



Remarks. — Nerita speciosa is described by Sowerby as being a species which 

 occurs of all sizes up to several inches in the Plymouth Limestone. Its height is 

 equal to its breadth. The upper whorls are convex, but the body- whorl is marked 

 by a shallow concentric depression between the suture and the shoulder. It will 

 be seen that the small specimen described above does not quite fulfil all these 

 conditions, but is still so similar that it may in all likelihood be regarded as a young 

 specimen of it, in which the concentric depression has not yet developed, or the 

 mouth so much increased in size as to render the height equal to the breadth. 

 Both our specimen and Sowerby's figure are so defective that the full characters 

 of the species cannot be made out. 



Affinities. — This shell differs from Euomphalus circularis, Phillips, 3 by its acute- 

 angled whorls and its closed umbilicus. 



Euomphalus Gualtieriatus, Schlot., 4 almost exactly corresponds upon the upper 



1 1879, Hall, ' Pal. N. T.,' vol. v, pt. 2, p. 21. pi. x, figs. 1—23, 25, 26. 



2 1842, Conrad, ' Journ. Acad. Nat. Sci. Phil.,' vol. viii, p. 276, pi. xvii, fig. 7. 



3 1841, Phillips, ' Pal. Fobs.,' p. 94, pi. xxxvi, fig. 171. 



4 1844, Goldf'uss, ' Petref. Germ.,' vol. iii, p. 81, pi. clxxxix, figs. 3 a, b. 



