MEGANTERIS. 95 
Remarks.—C. virgo is a very definite though rather variable species, and it is rare 
that a specimen remains doubtful after examination underalens. The pentagonal 
form, the sharp, pinched-in, erect beak, the straight or slightly convex or 
concave anterior margin, the beautiful arching rows of punctations, and, when 
present, the numerous low rounded ribs are clear characters; and even in badly 
preserved shells indications of one or other of them are generally discernible. 
The arrangement of the punctations is, unfortunately, not clearly represented 
in my figures. They form arching radial rows concave to the shoulders of the 
Shell. The low ribs do not seem a very constant character, not being observable 
in young or in all aged shells. 
Some old specimens have a slight sinus on each valve, which causes the 
anterior margins to be slightly concave, so that the shell sometimes becomes 
rather cornute: these shells are generally deeper than usual, and do not show 
any ribs. I am inclined to consider these as the most aged form of the species 
rather than as a distinct variety. 
The majority of the Lummaton specimens have lost their outer surface, and it 
is only then that the difficulty of determination occurs. 
It seems to me probable that Phillips’s figured specimen of 7’. sacculus belongs 
to the same species, and I am inclined to think that several of Davidson’s figures 
in his first Devonian Monograph (e.g. pl. 1, figs. 2, 3, 5, and 6) really represent 
specimens of C. virgo rather than of W. Whidbornei, with which he identifies them 
in his Supplement. 
It appears to me that the German shell identified by Maurer with Terebratula 
(Atrypa) Eurydice, Barrande, probably belongs to this species. As far as can be 
judged from his figure and description its external characters agree, and nothing 
is said of its internal arrangements. Barrande’s figures also resemble it. 
4. Genus.—Mecanteris, Suess, 1856. 
1. Mucanteris inornata, d’Orbigny, sp.? Pl. XII, figs. 1—1 0. 
1847. ArryPa 1noRNaAtA, d’Orbigny. Prodrome, p. 92. 
21855. Mxreanreris Arcutaci, Suess. Jahr. Akad. Wissensch., vol. xviii, p. 51, 
pls. i—iil. 
? 1876. — _— F. Romer. Leth. Pal., pl. xxiii, fig. 6. 
1889. oo tNorNATA, Barrois. Mém. Soc. Géol. Nord, vol. iii, p. 152, 
pl. x, fips, 5: 
Description.—Shell large, transversely oval. Ventral valve convex, especially 
near the margins. Dorsal valve flattish. Beak small, low, rather incurved, with 
