





MIDDLE BALA GROUP. 69 
Case and Reference to McCoy's 
Column of} i 3 Names and References; Observations, &c. Numbers and Localities. 
Drawers. | Synopsis: and Figures of Genera. 
Gm Pl.-1 1, fig. 20, p. 292. Murchisonia cancellatula, McCoy. a. 174*, Alt-yr- Anker, 
Meifod. 
Pl. 1k, fig. 4, p. 294, Murchisonia simplex, McCoy. Distinguished | Glenquhaple; a. 167, Alt- 
(not 1 1, fig. 21). from the next by a blunt median keel, and | yr-Anker. 
one above and below it. 
Gm Pl. 1k, fig. 43, p. 293. Murchisonia gyrogonia, McCoy (M. scalaris, | a. 174, Yspytty Evan. 
Salter, but this was named from very im- | Llanfechan. 
perfect specimens). 
Gm PL. 1K, fig. 42, p. 294, Murchisonia pulchra, McCoy (Sil. Foss. Irel. | Alt-yr-Anker; a. 215*, N. 
pl. 1, fig. 19). Perhaps a distinct species | of Tremadoc. 
from the Irish one, which is from Llan- 
dovery rocks. 
Gm Pl. 1 1, fig. 23, p. 298. Cyclonema lyrata, McCoy. Cyclonema is a | a.179*, Llansantfraid, Glyn 
Euomphalus. genus of Prof. Hall’s, intended for thin Ceiriog. 
shells of the Litorina group. These and all 
such shells were formerly referred to Turbo. 
Gm Pl. 1, fig. 36, p. 296. Cyclonema crebristria, McCoy. (Zurbo and | a. 173, Bala (Gelli Grin); 
Turbo crebristria. Holopea, McCoy). Mem. Geol. Surv. mt. | Alt-yr- Anker, Meifod ; 
p. 347, woodcut 14, fig. 5). A thin shell, | Mynydd Fron Frys, Chirk. 
spirally striate, ranges to May Hill Sand- 
stone. 
Gm Pl. 1 K, figs. 37, 38, p. 299. | Cyclonema triporcata, McCoy (possibly refer- | a. 173*, Cyrn- y - Brain, 
Euomphalus. able to the genus Trochonema). Wrexham. 
Gm Holopea, Hall. A genus of smooth or nearly 
smooth shells, like Litorina: but evidently 
not operculate as Turbo. It includes a great 
many of the ordinary univalves in Cam- 
brian and Silurian rocks, 
Gm Pl. 1 k, fig. 41, p. 296. Holopea Striatella, Sow. (Siluria, 2nd ed. pl. 7, | a.169*, Bryn Melyn, Bala; 
Trochus constrictus. fig. 4). a.169, Cymmerig Brook, do. 
Gm Holopea conica, exserta, lymneoides, &c. occur 
at Rhiwlas near Bala. (Mem. Geol. Surv. 
ul. woodcut 14, p. 347.) These shells were 
referred by Forbes to such living types as 
the floating Litiopa. (See Mem. Geol. 
Surv. Vol. 1. p. 346.) 
Gm Raphistoma, Hall. 

