Case and 
Column of) 
Drawers. | 

Gh 
Gh 
Gh 
Gh 
Gh 

MIDDLE CAMBRIAN. 

Reference to McCoy's 
Synopsis: and Figures of Genera. 
Brachiopods. 
Bivalves protected by up- | 
per and lower shells, not by 
side-plates as in ordinary bi- 

valves, 
RS) oa 
Brachiopods have _ spiral 
arms, which are probably the 
labial tentacles. The respi- 
ration is carried on, not by 
gills, but by the mantle-sur- 
face. Brachiopods (the horny | 
kinds) precede the ordinary 
bivalves in time. 

Univalves. 
(Sea Butterflies.) 
The Pteropods are greatly 
developed in the very oldest 
rocks; and are low forms of 
mollusks, floating and almost 
flying in deep water by means 
of the double-lobed foot. The 
breathing cavity is a ciliated 
surface. The operculum has 
been discovered in many spe- 
cies. 

| 

Names and References; Observations, &c. 
Numbers and Localities. 

MOLLUSCA Brachiopoda. 
Discina? pileolus sp. Salter. Minute cap-shaped 
horny Brachiopods are found in all the Pa- 
leozoic deposits. (For genus see Bala group). 
Obolella? sagittalis, Salter (Davidson, earliest 
Brach. Geol. Mag. 1868, Vol. v. pl. 15, 
figs. 17—24). The genus not quite certain, 
but Oboledla is common in old rocks. 
Obolella nucleata, MSS. A very small apicu- 
late species. 
Obolella maculata, Hicks, ib. pl. 16, figs. 1—3. 
Lingulella ferruginea, Salter (ib. pl. xv. figs. 
1—4). The earliest Lingule differed from 
modern ones in having a groove under the 
beak for the passage of the pedicle, and thus 
being more like Obolus. Quart. Geol. Journ. 
1867, Vol. xx. p. 340, fig. 1. (See p. 2.) 
Orthis Hicksii, n. sp., Davidson (ib. pl. 16, fig. 
17). Very like O. Carausii, Salter, but with 
a short hinge. (For genus, see Arenig Group.) 
MOLLUSCA Pteropoda. 
Theca obtusa, Salter (Mem. Geol. Surv. Vol. 11. 
p. 352, fig. 17). A large species of a genus 
like the much smaller living Cresevs. 
Theca corrugata, Salter (Quart. Geol. Journ. 
Vol. xx. pl. 13, fig. 10). A moderately broad 
species, with rugose lines of growth. 
Theca Homfrayi, Salter, n. s. 
than 7. corrugata. 
Theca penultima, Salter. [Dr. Hicks’ cabinet. ] 
Theca stiletto, Hicks. Brit. Assoc. Repts. 
Stenotheca cornucopie, Salter, new genus. 
Cyrtotheca hamula, Hicks. Like Theca, but 
strongly curved. 
Much longer 
| dach River. 
b. 268, 

St. David’s. (Presented by 
Dr. Hicks, 1869.) 
St. David's. (Presented by 
Dr. Hicks, 1869.) 
| a. 257, Gwynfynydd, Gold 
mines. a. 258, Cwm 
heisian. (Mr. Plant, 1869.) 
St. David’s. (Dr. Hicks.) 
St David’s. (Dr. Hicks.) 
a. 483, m sandstones at 
Porth Rhaw, St. David’s. 
(Dr. Hicks.) 
a. 4, Maentwrog falls, N. 
Wales. Mr. Ash. (Upper 
beds of the formation.) 
St. David’s. (Pres. Dr. 
Hicks.) b. 264, Rhaidr ddu 
valley, Maentwrog. (Mr. D. 
Homfray.) a. 259, a. 260, 
near Gold mines, Mawd- 
(Mr. Plant.) 
Tyddyngwladis, 
gold mines. (D. Homfray.) 
St. David’s. (Dr. Hicks.) 
a. 279, do. do. 
a. 280, do. do. 
