970 DR F. R. C. REED ON THE 



are practically absent or to a great extent unrecognisable ; and though many species 

 are local yet others occur in English, Welsh, and Irish localities in Bala beds ; the 

 general facies is thus predominantly British. North European relations are also 

 not wanting in the Drummuck Group, especially in the Starfish Bed. 



The Silurian beds have a marked British stamp, and the American elements seem 

 to have disappeared. In common with northern Europe, we may note the existence 

 of a widespread and dominant facies of a fairly uniform brachiopod fauna accompanied 

 by the development of local species or varieties. 



Conclusions. 



1. The Ordovician may be recognised as possessing two main brachiopod faunas, 

 the older one being limited to the Stinchar Limestone and Balclatchie Groups, the 

 newer one to the Whitehouse and Drummuck Groups. 



2. In the case of the Silurian the brachiopod faunas of the Mulloch Hill and 

 Saugh Hill Groups form one diviison, while those of the Camregan and Penkill 

 Groups are on the other hand linked together ; but the distinctive characters of 

 these two divisions are not very strongly marked. 



3. Each stratigraphical group of beds has a certain individuality in the com- 

 position of its brachiopod fauna, and usually possesses some peculiar species or varieties. 



4. The assemblage of species in the Stinchar Limestone and to a less extent in 

 the Balclatchie Group exhibits distinct American affinities. But these are lost in 

 the succeeding stratigraphical groups, and in the Silurian beds the European facies 

 is practically unmixed with alien elements. 



5. The predominance of local and peculiar species and varieties in the case of 

 the brachiopod fauna of the Girvan district on every horizon of the Ordovician and 

 Silurian formations is a distinctive feature, and gives to the whole a remarkable 

 individuality suggesting a considerable degree of isolation of this marine area. 



PRINCIPAL LITERATURE. 



1S48. Salter (in paper by Nicol), Proc. Geol. Soc Land., vol. iv, pp. 205, 206. 



1849. Salter, Quart. Journ. Geol. Soc, vol. v, p. 15, pi. i, fig. 4. 



1851. Salter, "List of some of the Silurian Fossils of Ayrshire," Quart. Journ. Geol. Soc, vol. vii, 



pp. 170-177, pis. viii, ix, x. 

 1851. M'Coy, Syn. Brit. Palseoz. Foss. Woodioardian Museum. 



1865. Gray, "Silurian Brachiopoda from near Girvan," Proc Nat. Hist. Soc Glasgow, i, p. 124. 

 1867. Murchison, Siluria (4th edit.), pp. 148, 163. 



1866-70. Davidson, Mon. Brit. Foss. Brachiopoda, vol. iii, pt. vii (Palseont. Soc), pp. 1-397, pis. i-1 (passim). 

 1870-71. Young, Proc. Nat. Hist. Soc Glasgoiu, ii, pp. 21, 166. 

 1873. Davidson, Trans. Geol. Soc Glasgow, Palseont. Ser., pt. i. 



1876. Armstrong and Young, Catal. West Scottish Fossils (List of Brachiopods, pp. 17, 18). 

 1882-1883. Davidson, Mon. Brit. Foss. Brachiopoda, vol. v, Supplement to the Brit. Silur. Brack., 



pp. 64-242, pis. iv-xvii (passim). 



