Ihe DEVONIAN FAUNA. 
twelve specimens in the Museum of Practical Geology, three in the British 
Museum, and twenty-one in Mr. Vicary’s Collection. 
Remarks.—The surface of the shell is covered with microscopic tubercles 
regularly arranged. 
One aberrant specimen has the marginal part of the fold trifid, consisting of a 
larger between two smaller plaits. One or two other shells show some irregularity 
in the fold besides an approach to the character by which Davidson distinguishes 
C. Demarlit. 
Another specimen has two or three oblique excentric ribs running down each 
slope of the ventral sinus. 
It appears to me from Hall’s description that CO. Hamiltonensis is undoubtedly 
a synonym. ‘The only difference which I can see is that the ribs of the American 
form are sometimes rather more numerous, but almost every one of Hall’s figures 
might have been drawn from Lummaton specimens in my Collection. Similarly 
I can find nothing to distinguish C. affinis, Billings, from the English shell. 
Oyrtia Dalmani, Hall,’ comes exactly between this species and C. heteroclita, 
var. multiplicata, Davidson. If these two forms are distinct species I should be 
inclined to regard it as a synonym of the latter shell. 
2. CYRTINA HETEROCLITA, var. MULTIPLICATA, Davidson. Pl. XII, figs. 18, 13 a. 
P?1859. Cryrrina Daumant, Hall. Pal. N. Y., vol. iii, p. 206, pl. xxiv, figs. 2a—y. 
1859. — rostrata, Hall. Ibid., vol. iii, p. 429, pl. xcvi, figs. 1—6. 
1864. — HETEROCLITA, var. MULTIPLICATA, Davidson. Brit. Foss. Brach., 
vol. in, pt. 6, p. 49, pl. ia, 
figs. 11—14. 
1882. _— — _ Davidson. Ibid., vol. v, pt. 1, 
p. 38, pl. ii, figs. 8—8 ce. 
1882. — — var. HISPANICA and MULTIPLICATA, Barrois. Mém. 
Soc. Géol. Nord, vol. ii, p. 260, pl. x, figs. 8 a—d, f. 
1887. — Demarui, Tschernyschew. Mém. Com. Géol., vol. ii, pt. 3, 
p. 80, pl. ix, figs. la—e. 
1889. —  HeETEROCLYTA, Barrois. Mém. Soc. Géol. Nord, vol. iii, p. 126. 
Localities—From Lummaton there are five specimens in my Collection, and three 
in the Torquay Museum. From Wolborough there is one in the Museum of Prac- 
tical Geology. Phillips’s figured specimen of Sp. cuspidata is in the British Museum. 
Remarks.—I am inclined to the opinion that this shell is distinct from 
QO. heteroclita. It is distinguished by its much greater comparative width, its 
narrower area, and its much smaller, more numerous, and more equal ribs. Its 
fold is large, and is not in a nearly regularly ascending order with the other ribs 
as in O. heteroclita. 
1 1861, Hall, ‘Pal. N. Y.,’ vol. iv, p. 206, pl. xxiv, figs. 2 a—y. 
