60 
UPPER CAMBRIAN. 

Case and 
Column of 
Drawers. 
Reference to McCoy's 
Synopsis: and Figures of Genera. 
Names and References; Observations, &c. 
Numbers and Localities. 

Gm 
Gl 
G1 
G1 

p. 193. 
O. retrorsistria. 
Pl. 14, fig. 12, p. 224, 
and note, p. 217. 
Spirifera, p. 194. 
Leptena spiriferoides, 
p- 246. 
Pl. 145, figs. 25—28, p. 227. 

Orthis, new sp. closely allied to O. biforata. 
Orthis alternata, Sow. (Siluria, 2nd ed. pl. 6, 
fig. 5). There can be no doubt the Welch 
fossil is the dwarf form of this common 
Horderley species. It is so easily distin- 
guished by the interior cast, and so hardly 
distinguishable by the exterior, that it has 
been confounded constantly with Stropho- 
mena alternata in British Works (the Synop- 
sis included). 
Orthis insularis, Eichwald (De Vern. Geol. 
Russia, t. 8, fig. 7). One of the rare group 
of smooth Orthides which occur in Bala or 
Caradoc rocks, over the N. Hemisphere at 
least. A very similar species is found in 
India. The dorsal valve is highly convex— 
the ventral, concave. 
Orthis Spiriferoides, McCoy (Siluria, 3rd ed. 
woodeut 37, p. 194). Of the same group 
with O. insularis, from which its strong 
striz or ribs easily distinguish it. 
Orthis simplex, McCoy (Sil. Foss. Ireland, pl. 3, 
fig. 18). Very like O. calligramma, and 
possibly a variety. 
Orthis protensa, Sow. (Siluria, 2nd ed. pl. 9, 
fig. 22) includes O. lata. Sow. Sil. System, 
t. 22, figs. 8,9. This common Llandovery 
species is very doubtfully recognized in the 
above locality. 
Orthis sarmentosa, McCoy, which is Orthis 
testudinaria in a crushed state. 


b. 233, Bala; b. 234, Nant- 
yr; a, 241, Tyn-y-Cabled. 
a, 144, Cerrig-y-Druidion, 
in millions. Penmachno ; 
Cernioge; Corwen; Bwlch 
Llandrillo; Cefn-y-Coedog ; 
Llangedwyn; Das Eithin, 
Hirnant, and Llanwddyn, 
Montgomeryshire; Pen Cer- 
rig Serth, N. of Bala; 
Glyn Diffwys; Meifod; 
Llangfyllin (the Carn Go- 
ran species is distinct and 
a sp. of Strophomena; see 
Mem. Geol. Surv. 1. p. 
340). 
b. 241*, Gelligrin, Bala; 
b. 241, Coniston. 
a. 146, Alt - yr - Anker; 
b. 251, Gaerfawr, Welch- 
pool; Llanfyllin; Bala; 
Horderley (and a hundred 
other Caradoc localities). 
Gelligrin; Llansantfraid. 
Cader Dinmael, Holyhead 
road, Denbyshire. 
