68 EOCENE MOLLUSCA. 
9. Mopiona Mircuenu, Morris. Tab. XIII, fig. 10. 
Mopiora Mircueni. Morris. Geol. Journ., vol. x, pt. 1, p. 158, t. 2, figs. 12, 13, 1854. 
= — Id. Catal. Brit. Foss., p. 211, 1854. 
Spec. Char. “ M. testa tenui, levi, subtrigond, anticé obtusa, posticé dilatatd ; cardine 
marginali recto,” 
“A somewhat trigonal, depressed, and dilated shell, with the umbones obtuse, the 
dorsal line straight, the byssal margin nearly straight or but very slightly curved, the 
surface nearly smooth or faintly marked by lines of growth.” (Morris.) 
Length, \ inch. 
Localities. New Cross, Deptford, Lee and Blackheath (Morris). 
“This species is near to Dreissena antiqua, Mcil., but the dorsal margin is more pro- 
duced, and the general character of the shell more spatulate.” 
“Not rare in the upper part of the Woolwich series, but it is rarely found perfect.” 
Mr. Prestwich’s cabinet. 
10. Moprona Nopuriwera, S. Wood. Tab. XIII, fig. 8, a, 2. 
Spee. Char. M. testa tenui, crregulariter trapeziformi, valde inequilaterali ; pedi- 
regione parvd, margine subrotundatd, siphoni-regione maynd, dilatatd ; extis radiatim 
striatd, striis magnis, bifurcatis, noduliferis ; margine ventral incurva. 
Shell thin, irregularly trapeziform, very inequilateral; the pedal region small and 
rounded, siphonal region expanded, covered with large, birfurcating, and nodulous radia- 
tions; ventral margin somewhat curved. 
Length, an inch. 
Locality. Barton (Hdwards), 
One specimen is all that I have seen, but its ornamentation is so different from 
that of any other species that I think it must be distinct. The striae which cover the 
entire surface are peculiar in bifurcating at a very early period. Near the umbo they do 
not amount to more than half a dozen, while at the outer margin of the siphonal region 
as many as thirty-five may be counted ; these striae are rather broader than the interme- 
diate spaces, and they are ornamented with a small knob or thickening at regular 
distances. 
11. Mopronta Nystu, Aicke, MSS., sec. Wyst. ‘Tab. XII, fig. 8, @, 4. 
Myritus Nysrur. Nyst. Coq. Foss. Belg., p. 270, pl. 20, fig. 8 3. 
— — Id. Rech. Coq. Foss. de Hoesselt et KI. Spau., p. 14, No. 35, pl. 3, 
fig. 35, fide Nyst. 
— Hastatus. Goldf. Petr. Germ., p. 179, pl. 131, fig. 13. 
