VOL. XIX. (2) 
USK INLIER (APPENDIX) 
^63 
Gosseletia (?) Tawneyi, sp. nov. [PI. VII., ftgs. 2, 2a.] 
Descyiption. — Shell large, sub-triaiigular, inequilateral, about one and a 
half times as long, as high, gently convex, most so near anterior end, somewhat 
compressed and flattened posteriorly. Beak elevated, pointed, incurved, di- 
rected forwards, rising high above hinge-line, situated at about one fourth the 
length of shell fi'om front end ; pre-umbona'. and post-umbonal slopes meeting 
at beak nearly at right-angles. Anterior end of shell short, steep, straight, 
inclined to inferior margin at about 75° ; anterior inferior angle blunt, 
abruptly rounded area beneath and in front of beak concave, not sharply 
limited. Inferior margin very slightly arched ; long. Posterior end of shell 
somewhat produced, bluntly pointed, the inferior and post-umbonal margins 
meeting at about 45°. Post-umbonal margin straight, oblique, about 
one and a half times as long as anterior end of shell. Surface of shell 
marked with fifty to sixty regular, equidistant, strong, straight, flattened, 
radiating ribs parallel to anterior and post-umbonal margins of shell ; ribs 
separated by shallow, rounded, regular, equal interspaces one and a half 
times to twice as wide as ribs, crossed by regular equidistant strong transverse 
concentric lines, not passing over ribs. Towards inferior margin the ribs 
become narrower and sharper, the interspaces wider, and the transverse 
lines closer and more numerous. 
Dimensions : Length, 5o"],(. 
Height. 35%. 
Horizon and Locality. — Ludlow beds behind Parish Room, 
near Llanbadoc .Church. 
Remarks. — •There are three specimens of tiiis species from 
Usk, all of which are right valves. It cannot be considered 
identical with the typical Cardium striatum Sow.' of the 
Aymestry Limestone and Lower Ludlow, which has usually been 
referred to the genus Ambonychia,^ but if congeneric with 
Ambonychia radiata Hall, of the Ordovician of North America, 
it should be put in the genus Byssonychia Ulrich. I am more 
inclined to refer our shell to the genus Gosseletia Barrois, which 
belongs to the same family or sub-family,^ but is not supposed 
to appear till Devonian times. Unfortunately, the internal 
characters of our shell are unknown ; so its generic place must 
remain uncertain. Gosseletia is a somewhat protean genus, 
but Freeh divides it into several groups. Our species seems 
to belong to the group of G. truncata (Roemer) (Freeh, of. cit., 
p. 1 19), and especially resembles G. trigona (Goldf.)'^ and 
G. carinata (Follmann)^ which occur in the Coblenzian beds of 
the Lower Devonian. 
1 Murchison, Silurian System, p. 614, pi. 6, fig. 2. 
2 McCoy, Syn. Palaeoz. Foss. Woodw. Mus., p. 264. 
3 Freeh, Devon. Aviculiden, Abhandl. kon. preuss. gcol. Landcsaiibt., Ud. ix., Heft 3, 1891, 
p. 109. 
4 Freeh, op. cU., p. 120, t. xii., hgs. 5-7a, text hgure 10. 
=; Freeh, op. cit.,p. 122, t. xii., figs. 8-ii ; t. xiv., fig. 3. 
