156 DEVONIAN FAUNA. 
behind, steep laterally, and overhanging the hinge. MHinge-line apparently 
shorter than the greatest width of the shell, which occurs at about two-thirds the 
way down from the hinge to the front margin. Front margin moderately and 
evenly convex. Surface covered with large close tubercles, bearing spines and 
arching out in excentric concave lines from the umbo to the margins. Dorsal 
valve deeply concave (except on the sides near the hinge, which are flat), marked 
with large pits, which correspond to the tubercles on the other valve, and are 
divided by narrow prominences. 
Size.—Length, 25 mm.; width, 25 mm.; depth, 9 mm. 
Localities —There are seventeen specimens in my Collection, four in the 
Torquay Museum, and three in the Woodwardian Museum, from Lummaton, and 
two in the Museum of Practical Geology from Newton. Sowerby figures it from 
Plymouth, and Davidson from Hast Ogwell. 
Remarks.—A small specimen of this species was figured by Sowerby with the 
remark that it was “‘ probably the young of Leptana fragaria (i. e. P. subaculeata) ; 
the tubercles are more numerous in proportion to the size.” Itis, however, clearly 
distinct from that shell. My specimens vary in size, but never attain the 
dimensions of the full-grown P. subaculeata. They are also distinguished from it 
by the closeness, size, and regularity of the tubercles, the greater length of the 
shell, and the narrowness and prominence of the umbonal parts of the ventral 
valve. They also differ from its young forms, which are characterised by very 
shght tuberculation and very indefinite and broadly rounded umbones, thus 
preserving the characters of the full-grown shell. These differences are constant, 
and are too great to allow it to be regarded as a variety of that species, though 
some rather doubtful specimens may occur. 
Davidson figured a full-sized specimen under the name of Strophalosia 
productoides from Kast Ogwell, but he does not quote Sowerby’s figure in his list 
of synonyms. It certainly seems to me that it cannot be the same as that species, 
as it differs greatly in the size, number, and character of its tubercles, its greater 
length, and other particulars. I-therefore am obliged to regard it as a separate 
species, and I know no foreign shell which approaches it. 
As it is only on the strength of these specimens that St. productoides has been 
included in the list of Lummaton fossils, that shell must consequently be removed 
therefrom. It occurs, however, in the ‘‘ Pleurodictyum-beds”’ at Meadfoot. 
3. Propuoteuna, sp. Pl. XVII, figs. 12, 12 a. 
Description.—Ventral valve evenly convex, transverse, semi-oval. Beak small, 
not extending above hinge-line, depressed. Hinge-margin as wide as the shell. 
