LOWER BALA GROUP. 


Case and 
Column of 
Drawers. 
Reference to McCoy’s 
Synopsis: and Figures of Genera. 
37 

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


Gk 
PL 14, f. 15, p. 301. 
Pl. 11, f. 13, p. 300, as 
G M. magna. 


I 
ay (°) 
@k5 . 
O. subundulatum, p. 317. 

Euomphalus, sp. 
Eccyliomphalus? scoticus, McCoy. The true 
Eccyliomphalus of Portlock is a Pteropod; 
this may be Phanerotinus of Sowerby. 
Heteropoda, Blainville  (Nucleobranchiata, 
Rang). All or most living forms of this 
group are thin light shells; but there seems 
much reason for Dr. Woodward’s opinion, that 
theheavy Bellerophon and Maclureawere solid 
representatives of this low order of Molluscs. 
Maclurea Logani, Salter (Geol. Survey, Canada 
Decade I. pl. 1). The proportions of the 
mouth and whorls of this massive shell agree 
better with MZ Logani than the great M. 
magna of the Chazy limestone. 
Cephalopoda, Cuvier. The tetrabranchiate fami- 
lies (only) are known in Paleozoic rocks— 
and Nautiloid and Orthoceras-like forms 
are among the very earliest known Molluscs, 
except Pteropoda and Brachiopoda. ‘They 
are particularly abundant in the representa- 
tives of the Llandeilo flag or Lower Bala 
groups. 
Cyrtoceras multicameratum, Hall. Hall’s sp. 
is from Trenton limestone, which represents 
Middle Bala. Many forms migrated in 
Cambrian times eastward from America, 
and are consequently of older date there 
than in Britain. But few follow a reverse 
order of progression. 
Orthoceras (centrale, Hisinger?), Leth. Suec. 
t. 9, fig. 4 Not likely to be Hisinger’s 
Swedish species. 

Orthoceras fluctuatum, Salter, n. sp. Coarser 
strie than O. subundulatum, Portl. and 
apparently more bent still than in that 
species. 


S. W. 
Bala 2) 
a. 91, Knockdollian, Ayr- 
shire, 
of Pwllheli (Mid. 
a. 89, Colmonel, Stinchar 
River, Ayrshire. It also 
occurs at Bugon, and other 
Ayrshire localities. 
a. 88, Knockdollian Mt., 
3 miles from Ballintrae, 
Ayrshire. 
a. 87, Llandeilo. 
a. 611, Wellfield, Builth, 
in the hard volcanic flag. 
