96 CRETACEOUS LAMELLIBRANCHIA. 
Distribution —Greensand of Blackdown. Greensand (chert beds) of Woodlands 
Covert, Great Haldon. Upper Greensand of Black Ven and Devizes. Cenomanian 
(Me¥er’s Bed 12) of Dunscombe. + Gault of Black Ven. 
Mopio.a Lickrimnsis (2 Orbigqny), 1844. Plate XVI, figs. 4a, b, 5a, b, 6. 
1844. Myrinus LiceriEensts, A. d’Orbiyny. Pal. Franc. Terr. Crét., vol. iii, 
p. 274, pl. cccxl, figs. 1, 2. 
1850. — = = Prodr. de Pal., vol. ii, p. 165. 
1867. — = EL. Gueranger. Album Paléont. de la Sarthe, p. 17, 
pl. xxu, figs. 2—4. 
1867. Moprona LicERriEeNsIs, F. J. Pictet and G. Campiche. Foss. Terr. Crét. Ste. 
Croix (Matcér. Pal. Suisse, ser. 4), p. 509. 
? 1876. — — D. Brauns. Zeitschr. f. d. gesammt. Naturwiss., 
vol. xlvi, p. 874. 
? 1883. —  ypica, A. Fritsch. Stud. im Gebiete der béhm. Kreideformat., 
MOQ 
ii. Die Iserschichten, p. 106, fig. 73. 
? Non 1846. Myrinus (Moproua) ticeriensis, A. EH. Reuss. Die Verstein. der béhm. 
Kveideformat., pt. 2, p. 16, pl. xxxiii, 
fig. 3. 
Measurements : 
(1) (2) 
Length , ; : ‘ : 89 . : 60 mm. 
Greatest height (perpendicular to 
length) . : ; ; : 40 ; : DAS). pp 
Thickness. F ; : ; 34. : : 24 
(1) and (2) from the Perna-bed of Athertfield. 
Afjinities.—This species agrees with M. reversa, Sowerby, and seems to be 
distinguished only by the crimp-like ornament in the spaces between the ribs; this 
is usually best developed on the dorsal and postero-ventral parts of the valves, and 
seems always to be absent on the anterior region. The specimens of M. reversa 
from Blackdown do not show that ornament,’ and its absence can scarcely be 
explamed by imperfect preservation, since other finer ornament is clearly shown on 
some specimens. On the other hand, the possibility of the two species being 
identical is supported by the great variability in the development of the crimp-like 
ornament in M,. ligeriensis. On some specimens from the Cenomanian of Orbiquet 
it is very faint, but on one from Le Mans (preserved in the Ecole des Mines, Paris) 
the crimp-ornament is stronger and more continuous than the concentric ornament. 
' One specimen seems to show a very faint trace of it near the hinge-margin. 
