38 
DEVONIAN FAUNA. 
Affinities. — Nucula ohsoleta, Groldfuss,^ is flatter, and has a more central and 
perhaps less prominent umbo, and a more convex inferior margin. 
Nucula tumida, Phillips," seems a more evenly rounded shell, with a 
smaller umbo. 
Nucula plicata, Phillips,* as first described, is altogether a more oval shell ; as 
given by Dames* it is more similar, but differs in being very much smaller, in 
being more produced in the infero-posterior corner, and in having the umbo 
more central. 
Nucula lineata, Phillips,^ has a more elevated umbo, a larger anterior side, 
and very regular concentric ridges. Semenow and Moller" refer to it some casts 
which differ from the present species in the same particulars, except that the 
surface-ornament is not shown. 
In Nucula diluviana, Steininger,''' the umbones are less posterior. 
Lutraria prisca, Goldfuss,^ and L. inflata, Steininger,^ are so similar in shape 
as to suggest relationship. From both shells it is, however, distinguished by 
being less truncated and oblique at the postero-inferior corner. 
Nucula Bandalli, Hall,^° while very like it, has a more ovate form, with less 
posterior umbones and a less abrupt posterior side. 
N. extrema, Barrande," also approaches it, but is much flatter, and has a less 
elevated and more oblique umbo. 
1 1840, Miinster, ' Beitr.,' pt. 3, p. 54, pi. ii, fig. 9. 
2 1834-40, Goldfuss, 'Petref. Germ.,' vol. ii, p. 151, pi. cxxiv, fig. 6. 
3 1841, Phillips, ' Pal. Foss.,' p. 38, pi. xviii, fig. 63. 
* 1868, Dames, ' Zeitscb. Deuts. GeoL Gesell.,' vol. xx, p. 502, pi. x, figs. 8 a, h. 
5 1841, Phillips, ' Pal. Foss.,' p. 39, pi. xviii, figs. 64 a, a—d, and 64 13, a, b. 
6 1863, Semenow and Moller, ' Mel. Phys. et Chim.,' vol. v, p. 678, pi. iv, fig. 11. 
7 1853, Steininger, ' Geogn. Beschr. Eifel,' p. 54, pi. iii, figs. 8 a, b, c. 
8 1834-40, Goldfuss, ' Petref. Germ.,' vol. ii, p. 259, pi. cliii, figs. 9 c, b. 
9 1853, Steininger, ' Geogn. Beschr. Eifel,' p. 50, pi. iii, figs. 1 a, b. 
10 1885, Hall, ' Pal. N. T.,' vol. v, pt. 1, sect. 2, p. 315, pi. xlv, figs. 6—10, 16, 23, 26, 27 ; and 
pi. xciii, figs. 1 — 3. 
11 1881, Barrande, ' Syst. Sil. Boh^me,' vol. vi, pi. cclxxiii, figs. 3, i— 9, Et. D, 
