50 
DEVONIAN FAUNA. 
Mytilhis prisms, Goldfuss/ is straighter posteriorly and narrower. 
Mytilarca Canadensis, Billings," and Gardiomorpha mytiloidea, F. A. Eomer,^ 
are much deeper shells, with more acute umbones, and straight anterior sides. 
III. Family. — AvicuLiDiB, d'Orbigny, 1843. 
I. Sub-family. — Ambonyohin^, Miller. 
1. Genus. — Gosseletia, Barrois, 1881.* 
Shell equivalve, inequilateral, gibbous, obHque ; greatest thickness along a 
line near the front margin dividing the shell into two regions, of which the 
posterior forms an obtuse wing, while the anterior is short and steep. Beaks 
prominent, not recurved, facing forward. Surface marked with numerous fine 
growth- strise. Hinge with a ridge running backwards, on each side of which is a 
grooved ligamental area. Cardinal teeth three. 
This genus has been described from the Devonian of Spain and America. 
1. Gosseletia (?) sp. PI. IV, figs. 6, 6 a. 
Description. — Lower part of left valve of moderate size. Anterior margin 
oblique, straight. Inferior margin short, very convex. Posterior margin nearly 
straight Back divided by a rounded angle of greatest elevation running near and 
parallel to the front margin, before which the shell is steep, and behind which it is 
obliquely flattened. Surface covered with very fine, distant, minute, regular, 
concentric lines. 
Locality. — Lummaton. A single fragmentary specimen is in my Collection. 
Remarks. — The only specimen I know is too fragmentary for anything like a 
full description, as the umbo, hinge, and upper part of the shell is entirely wanting. 
The part, however, which remains falls well within the limits of Barrois's genus, 
and so nearly resembles the American species G. triquetra, Conrad,^ sp., both in 
shape and ornament as to render it most probable that this is its true position. 
Specifically, however, I think it difiers from the American form, as the base is 
more evenly rounded, and it seems a wider shell. 
1 1834-40, Goldfuss, ' Petref. aerm.,' vol. ii, p. 284, pi. cl, fig. 13. 
3 1874, Billings, 'Palaeozoic Fossils,' vol. ii, pt. l,p. 52, pi. iv, figs. 2, 2a. 
3 1860, F. A. Eomer, ' Beitr.,' pt. 4, p. 163, pi. xxv, figs. 14 a, b. 
1881, Barrois, ' Ann. Soc. Ge'ol. Nord,' vol, viii, p. 176. 
5 1838, Conrad, ' Geol. Surv. N. T. Ann. Rept.,' p. 116 ; and 1885, Hall, ' Pal. N. ¥.,' vol. v, 
pt. 1, sect. 1, p. 265, pi. xsxi, figs. 9 — 17 ; and pi. Ixxxvii, fig. 12. 
