﻿PTERINOPECTEN. 



83 



tions, which sometimes break the course of the ribs, or even obliterate them. 

 Shell-structure apparently thin. 



Size of left valve. — Length about 38 mm., breadth about 35 mm., depth 

 about 6 mm. 



Localities. — There are two specimens from Lummaton in my Collection, and 

 one from Wolborough in Mr. Vicary's Collection. 



Remarks. — Our specimens of this shell are defective. The front part only is 

 shown in two and the rear part in the third. Nevertheless, they mutually pre- 

 sent so close a resemblance to Avicnlopecten Ci/bele, Barrande, that I have little 

 hesitation in identifying them with that species. They are to be distinguished by 

 their squarish shape, their sub-central umbo, their numerous regular, concentric 

 bulges, their numerous smooth rays, of which a few seem slightly larger than 

 the rest, and their diffuse anterior ear. The shape of the latter is especially 

 characteristic ; it is only marked by a slight concavity of the margin, and by a 

 gentle convexity of the surface succeeded by a concavity. 



In Mr. Vicary's specimen the rays are worn off from most of the concave 

 slopes of the bulges, which thus assume the appearance of smooth transverse 

 bands. The same seems to have occurred in Bohemian specimens. 



It is not clear from Barrande's figures whether the rays are close or distant. 



The shell seems to have reached a considerably larger size in England than 

 in Bohemia. 



Affinities. — Avicnlopecten Jugleri, F. A. Romer, 1 has very much smaller wings. 

 Pterinopecten Neptuni, Goldfuss, sp., 2 is less oblique and has coarser ribs. It 

 seems otherwise very closely related. 



3. Pterinopecten consolans, Barrande, PI. IX, fig. 11. 



1881. Avicttlopecten consolans, Barrande. Syst. Sil. Bohein., vol. vi, pi. ccxxii, 



figs. 2, l-ii, Et. F. 



? 1884. Pteeinopecten Veetumnus, Hall. Pal. N. Y., vol. v, pt. 1, p. 71, pi. v, 



figs. 1 — 8 ; and pi. lxxxiii, figs. 2,3. 

 1889. Avicttlopecten consolans, Whiclborne. Geol. Mag., dec. 3, vol. vi, p. 78. 

 1891. — — Freeh. Abhandl. Geol. Specialk. Preuss., 



Band ix, pt. 3, p. 26, pi. ii, fig. 6. 



Description. — Left valve of moderate size, convex, transverse, slightly oblique. 

 Umbo small, not prominent, situated at about the anterior third of the length. 



1 1843, F. A. Eomer, ' Verst. Harzgeb.,' p. 21, pi. vi, fig. 4 ; and 1891, Freeh, 'Abhandl. Geol. 

 Specialk. Preuss.,' Band ix, pt. 3, p. IS, pi. xvii, fig. 2. 



2 1834-40, Goldfuss, ' Petref. Germ.,' vol. ii, p. 125, pi. cxvi, fig. 4 ; and 1891, Freeh, ' Abhandl. 

 Geol. Specialk. Preuss.,' Band ix, pt. 3, p. 18, pi. ii, figs. 1, 2. 



