BRACHIOPODA. 
97 
lamellae, and not between the primary and secondary lamellae as usual; further¬ 
more, these accessory lamellae are very narrow.^ 
While from our present knowledge the group of Seminula must be regarded as 
confined to the Carboniferous (and Permian ?) formations, there is a little species 
in the white sandstone of Pendleton, Indiana, in a fauna having much similar¬ 
ity to that of the Schoharie grit of New York, which has many of the internal 
shell-characters of A. subtilita. This species, Athyris Rogersi,-\ sp. nov., occurs 
in the condition of internal casts which show the form of the shell and the 
muscular impressions as described for Seminula, the subquadrate and perforate 
hinge-plate and the faint median septum in the brachial valve. The brachidium 
has not been developed. No other Devonian species showing similar affinities 
is known. 
From our present knowledge, the athyroids, of the American palaeozoic 
faunas appeared with this form, at the opening of the Devonian age. Mr. 
Davidson has illustrated the spirals of a Wenlock species, Terebratula l&viuscula, 
Sowerby,! which seemed to show the existence of accessory lamellae. This 
little shell has recently been closely investigated by the Rev. Norman Glass,§ 
who finds that the loop forms no saddle, and that the intercalary lamellae are 
* Iti the progress of this work some shells were received from a collection formerly belonging to the Rev. 
H. Heezbr, of Berea, Ohio, bearing the label ‘■‘Athyris 
ambigua, Cork, Ireland.” The specimens possess a 
rather more transverse form than usual in A. ambigzia, 
and the faint cancellation of the exfoliated sui'face 
would indicate that it was originally spinous oi‘ lamel- 
lose. It is evident that the species is not A. ambigua, 
but its specific identity is still uncertain. There is, 
howevei-, no species of Athyris of which the looji is 
known, where this organ (as shown in the accompany¬ 
ing figure) is so short and so closely confined to the 
umbonal region. The lateral branches originate from 
the primary lamellffi with a very slight anterior curve, 
being almost horizontal for a short distance ; the um¬ 
bonal blades of the primary lamellse are very broad, 
beginning in an abrupt angle with the crura and hav¬ 
ing a slight curvature. The saddle is entire on the 
anterior margin and not fimbriate. 
t Named for Dr. Benjamin Rogers, of Pendleton, in recognition of his interest in the development of 
the fauna of this locality. 
I British Silurian Brachiopoda, Supplement, p. 101, jil. iv, figs. 24-26. 
§ Geological Magazine, Dec. Ill, vol. viii, p. 495. 1891. 
Fig. 72. 
Loop of Athyris, sp. ?, Carboniferous limestone, Cork (?). 
(C.) 
