E. Billings on the Genus Athyris. 59 
of rejecting Spirigera altogether; others of retaining it. It is 
not, therefore, a case clearly within the rule; and as there was 
much doubt, the best course to take, as soon as it was found pos- 
sible to do so, was taken by Mr. Davidson. He decided in favor 
of preserving the name. 
Authors who have adopted the classification.—In 1856, Profes- 
sors H. G. Bronn and F. Roemer, in the third edition of Bronn’s 
Lethea Geognostica adopted Davidson’s classification and copied 
his diagnosis of both genera in full, They cited A. tumida as 
the type of Athyris. ‘Die typische Art ist Athyris tumida Me- 
Coy. (Airypa tumida Dalman.) Andere Arten sind A. Hereulea 
(Terebratula Herculea Barrande), A. pseudo-scalprum (Zerebratula 
pseudo-scalprum Barrande), A. scalprum (Terebratula scalprum 
Fred. Roemer).” Op. cit.,p. 831. es 
They also recognized S. concentrica as the type of Spirigera. 
“Die typische Art ist Sp. concentrica (Terebratula concentrica 
Bronn). Andere Arten sind Sp. pectinifera (Atrypa pectinifera 
werby), aus dem Zechstein, Sp. Roissyi, (Sp. de Roissyt Le- 
véillé),” &c., Op. cit., p. 832. : : 
In the same year Kichwald placed A. tumida in Athyris and 
S. concentrica in Spirigera.* ete 
In 1860 he also introduced the same classification in his great 
work on the Paleontology of Russia. The Russian species are 
A. tumida, didyma, ungula, cassidea, S. concentrica and ambigua.t 
n my studies of the Canadian Brachiopoda I had no occasion 
to describe any species of this group until 1859, when I commen- 
a series of papers on the Devonian Fossils of Canada 
ih At that time I had not fully investigated the subject, but 
understood fi : i r. 
rom a bi ce 
“ Geologist” (vol. 1, 456), and also from Woodward s “Manual 
“There is much difference of opinion as to the propriety of retaining 
this generic name. It implies that the shells have no foramen in the 
using D’Orbigny’s appellation Spirigera instead of Athyris. Nearly all of 
the Silurian species, and some of those from the Devonian rocks, have the 
beak so strongly incurved, that no foramen can be seen. For such, at 
. Beitrag sur geographischen Verbreiisg der fossilen Thiere Russlands, Bull. 
Beep Bi Manes 0h PE ca oy tk pr ar 
Tn this work Bik: Woodard: separates ferista (although with doubt) as a sub- : 
genus, and refers A. tumida to Athyris. ee. 45 
