22 Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 
With these especial aims I paid a visit to the Girvan district in 
1885, and was then able to satisfy myself upon the following points :— 
1. The diabases, syenites, gabbros and serpentines occurring in the 
altered patches within the limits of the Girvan district proper are many 
(if not all) of post-Girvan (post-Silurian ?) age. They occasionally 
traverse, and usually harden and alter, such of the Lower Girvan 
rocks as they are locally associated with (as at Shallock Hill, Meadow- 
head, Byne Hill, Laggan Hill, Craighead Hill, and the slopes of the 
valley of the Stinchar) ; so that (exception being made of some of 
the strata of the last three areas named) the igneous and altered rocks 
of these patches have no claim to be ranked as of Ballantrae age. 
These post-Girvan igneous rocks have intruded themselves mainly 
in sheets along the many anticlinal arches into which the Girvan 
rocks are thrown, either between the Girvan rocks and the Ballantrae 
rocks proper, or among the limestones and conglomerates. etc., which 
make up the basal members (Barr or Stinchar Series) of the Girvan 
succession. 
2. Similar igneous rocks (apparently of corresponding age) are 
met with in mass within the limits of the Ballantrae region itself, 
and have been equally operative in hardening and altering the 
enveloping strata. But in addition to these post-Girvan masses and 
the infolded Girvan (Stinchar) limestones and conglomerates of the 
region already referred to, the Ballantrae rock complex actually 
includes great thicknesses of stratiform rock—volcanic (contempo- 
raneous), sedimentary, altered and unaltered; some of the last of 
which are distinctly of pre-Girvan date (and consequently of higher 
antiquity than any fossiliferous stratum yet recognized in the Southern 
Uplands)—for they contain locally a well-marked Graptolitic fauna 
of Arenig age. 
The Arenig fossils occur in certain hardened black shales on the 
sea-shore at Bennane Head, about the centre of the Ballantrae area. 
These shales are associated with siliceous and felspathic grits and 
flagstones, purple shales, conglomerates and various igneous and 
altered rocks. Similar black shales occur near Lendalfoot. on the 
north-western slopes of Craighead Hill and elsewhere, but hitherto 
they have afforded no determinable fossils. 
The recognizable forms collected by myself from the Bennane 
shales include : 
Phyllograptus typus, Hall. Didymograptus extensus, Hall. 
Tetragraptus quadribrachiatus, Hall. ss bifidus, Hall. 
an bryonoides, Hall. Caryocaris Wrightii, Salter. 
* Sruticosus, Hall. Associated with forms of Dietyonema, 
99 Biysbyi (caduceus) ?, Hall. Lingula and Obolella. 
It is almost unnecessary perhaps to point out that we have here 
a Scottish representative of the well-marked fauna of the middle 
zones of the Arenig Quebec or first Ordovician fauna of South 
Britain, Northern Europe, and Hastern America. Not only is the 
general facies of the fauna’ of the well-known Arenig Point Levis, 
or Skiddaw type, but the Bennane forms occur—as will be apparent 
from a study of the following table—always in the same association, 
