394 SECTIONAL TRANSACTIONS.—C. 
On the American continent the Richmond formation is claimed to be Ordo- 
vician, and both Lower and Upper Clinton to be Upper Llandovery. Jt is not 
certain that the Lower Llandovery fauna is represented, unless the Upper 
Medinan, Girandeau, Edgewood, and Brassfield are of this age. The latter is, 
however, more probably Upper Llandovery. The absence of satisfactory equiva- 
lents of the Lower Llandovery is attributed to the incompleteness of the 
American succession in comparison with Britain. 
26. Prof. O. T. Jonss.—The Llandovery Rocks of Llandovery. 
A brief summary of the work of previous observers in the district is given. 
In the district around Llandovery three main divisions (A-C) can be distinguished, 
each capable of subdivision on lithological or faunal grounds as follows :— 
It. 
C. Upper Division. Mudstones, shales and grits ; Pentamerus 
oblongus occurs commonly. 
C6. Thin-bedded micaceous shales with bands of micaceous sand- 
stone; thickness considerable. 
C5. Soft greenish- blue or dark-blue mudstones. 380 
C4. Dark-green fucoidal sandstones with bands of shale and quartzitic 
sandstone . : : 270 
C3. Pale greenish mydstones passing up into greenish shales : 270 
C2. Like C3. : ; 250 
Cl. Hard greenish mudstones ‘with calcareous "nodules. ‘Mono- 
graptus sedqwicki common. ‘ ; : : ; 400 
UnNcONFORMITY. 
B. Middle Division. Greenish mudstones and shales. P. oblongus 
found only at base. Monograptus decipiens, M. regularis 
and Orthograptus cyperoides also occur. 
B3. Hard greenish mudstones : : . : 300 
B2. Blue micaceous mudstones, poorly exposed “ E 250 
Bl. Hard greenish mudstones, with small calcareous nodules. 250 
A. Lower Division. Sandy mudstones and blue mudstones 
passing down into shales and sandstones. Monograptus 
ancommodus, &c. 
A4. Hard tough thick-bedded sandy mudstones with some thin 
bands of jointed quartzitic sandstones. 700 
A3. Blue sandy micaceous barren mudstones with 1 in. 2 in. fossili- 
ferous gritty micaceous bands . 400 
A2. Grey shaly mudstones without hard bands passing down into 
soft dark-blue shales with thin beds of grey sandstone. 
Climacograptus tornquisti at top. 900 
Al. Basal group of hard grey quartzitic sandstones and occasional 
thin conglomerate with interbedded smooth iron-stained 
dark-blue shales . 4 5 ; , : 150 
The basement beds (Al) rest upon Upper Bala rocks and the highest group (C6) is 
overlain, in places, unconformably, by the Wenlock shales; the total thickness of 
the formation near Llandovery thus exceeds 4,500 feet. A great unconformity has 
been mapped at the base of the Middle Division, and another at the base of the Upper. 
The fossils are mainly brachiopods and trilobites, and the chief forms from each 
subdivision are enumerated. 
27. Mr. G. Anprew.—The Llandovery Rocks west of Builth, 
Breconshire. 
A brief summary of the work of previous observers is given. The succession is 
as follows :— 
Wenlock (D). Blue, thinly bedded calcareous mudstones, with Ft. 
Cyrtograptus murchisoni, Monograptus prio- 
don, M. crenulatus, &c. These beds over- 
step rapidly southwards, and eventually lie 
directly on the Bala. 
