﻿72 



DEVONIAN FAUNA. 



shells, though until better specimens come to hand some doubt must remain both 

 as to their specific value and their relationship to foreign forms. 



In none of our specimens is the front wing clearly seen ; but in other respects 

 they agree accurately with Avicula Wurmii, F. A. Romer, both as originally 

 described, and as given by Freeh. The same shell has been described from 

 Russia by Tschernyschew. 



Freeh considers the shell referred to Romer's species by Maurer as doubtful, 

 and it certainly has decidedly fewer ribs than are seen in our English specimens. 



Avicula trapeziformis, F. A. Romer, is a very imperfectly described shell. It 

 seems to me that it may possibly be identical with the present species. 



Pterinea normata, Barrande, also appears to be identical, although in some of 

 Barrande's figures the ribs appear to be more distant and to alternate more 

 rarely ; and in others to be closer and finer. 



Pt. perdita, Barrande, has every appearance of being the opposite valve of 

 Pt. normata. Barrande mentions that his specimen is lost, which may be the 

 reason he has not united them. 



Affinities. — Avicula intermedia, (Ehlert, 1 is very similar, and Freeh seems half 

 inclined to regard it as identical. It chiefly differs from the German species 

 (including our specimens) by its much greater length and much more triangular 

 shape. 



A. Trigeri, (Ehlert, 2 is more transverse and more finely ribbed. 

 Pterinea Morleti, (Ehlert and Davoust, 3 is broader, less oblique, and more finely 

 and evenly ribbed. 



Avicula pedinoides, Sowerby, 4 while presenting in his fragmentary type a 

 somewhat similar appearance, is easily distinguished by its large anterior wing 

 and much more central umbo. 



Sandberger 5 describes a shell under the name of Pterinea clathrata, with which 

 he identifies both A. Wurmii, F. A. Romer, and A. texturata, but which is certainly 

 distinct from the former, and most probably from the latter. From A. Wurmii it 

 is at once to be distinguished by its transverseness and its very large anterior 

 wing, as well as by its prominent transverse stria3. 



Freeh seems to doubt whether Actinopteria subdecussata, Hall, 6 is not identical. 

 While it certainly is extremely similar, it seems to me that its ornamentation is 



1 1881, (Ehlert, 'Mem. Soc. Geo!. Fr.,' ser. 3, vol. ii, p. 21, pi. iii, figs. 1— 1 c. 



2 1888, ibid., ser. 3, vol. xvi, p. 647, pi. xiv, fig. 4. 



1 L880, (Ehlert and Davoust, ibid., ser. 3, vol. vii, p. 715, pi. xv, fig. 9. 

 1 I M(), Sowerby, ' Trans. Geol. Soc.,' ser. 2, vol. vi, pt. 3, pi. liv, fig. 2. 



5 185:5, Sandberger, ' Verst. Khein. Nassau,' p. 286, pi. xxix, fig. 18. 



6 1884, Hall, 'Pal. N. Y.,' vol. v, pt. 1, p. 110, pi. xvii, figs. 23, 25—27, 29—31; and pi. xix, 

 fig. 25. 



