BRITISH AVONIAN CONODONT FAUNAS 51 
Only three samples (ANS 15, 43, 388) have yielded any conodonts, and of these there 
are few diagnostic species, although the presence of subspecies of G. givtyi indicates an 
overall correlation with the D Zone of the North Crop (Fig. 55). 
The Lower Limestone Group has yielded a small fauna from the Hurlet Limestone 
(HURLET A, C, E) which is characterized by G. girtyi girtyi and G. girtyi simplex. 
The Lower Hosie Limestone (HOSIE 1) yields a larger but essentially similar fauna, 
but the Middle Hosie Limestone (HOSIE 2A-C) has yielded over 1,000 conodonts 
and is characterized by G. girtyi collinsoni subsp. nov., as well as G. mononodosus 
sp. noy. and G. nodosus, which suggests a correlation with a high level in the D3 
Subzone of the North Crop. 
Ayrshire 
The Broadstone Limestone (BRAU 1-8) yielded a very meagre conodont fauna, 
having an average yield of only one conodont per kilogram of rock. The fauna is 
characteristic of the Cavusgnathus unicorms—A patognathus Zone (Fig. 58). 
The Dockra Limestone (BRAU 9g and 10) yields a large and well preserved conodont 
fauna. G. girtyi simplex and G. girtyi girtyi each represent almost one third of the 
total specimens in each sample studied. The presence of G. girtyi turritus at the base 
of the Dockra Limestone shows this to be within the G.g. collinsont Zone. 
The Hosie Limestones from Glengarnock (GLEN 1-19) have yielded abundant 
and well preserved conodont faunas, which include three specimens of G. g. turritus, 
which is indicative of the G.g. collinsont Zone. 
The Index Limestone (DR IN 1-GO IN 3) of Ayrshire has yielded faunas which are 
dominated by Gnathodus girtyi girty1, G. girtyt simplex and G. girtyi collinsom 
subsp. nov., as well as other species characteristic of the Gnathodus girtyi collinsom 
Zone of the North Crop. 
The Lower Linn Spout Limestone (LINL, 1, 3) has yielded only five conodont 
specimens. These include G. girtyi girty1, Mestognathus sp. and Magnilaterella sp. 
which in themselves are not diagnostic. 
The Upper Linn Spout (U.LIN 1-7) has a small fauna which includes G. bilineatus, 
G. mononodosus sp. nov., G. nodosus and G. commutatus. 
We can make no precise correlation of this formation, but, clearly, the presence of 
some 300 ft. of underlying strata within the G. givtyi collinsom: Zone of Ayrshire 
implies a relatively young age. We have assigned the Upper Limestone Group to the 
Eumorphoceras Zone on the basis of Currie’s (1954 : 535) goniatite faunas from the 
Index Limestone. 
Roxburghshire 
The main Algal “ Series ”’ of Garwood in Harden Burn yielded abundant and well 
preserved conodont faunas. These were dominated by the Polygnathus lacinatus 
group and other species including Cavusgnathus cristatus and Taphrognathus varians. 
In spite of some differences between this fauna and those of the Avon Gorge, the 
presence of polygnathids shows the Roxburghshire faunas to be equivalent to the 
early C Beds of the Avon Gorge. This accords well with the tentative C; age 
assigned to these beds by Garwood (1931). 
