205 
1916-17.] The Hurlet Sequence and the Abden Fauna. 
stone, with occasional bands of Litliostrotion, and with an occasional solitary 
coral. According to Dr Young, the principal fossils of the Campsie Main 
Limestone are Productus, Spirifer, and Athyris, but it cannot be pro- 
nounced a rich fossiliferous deposit. He also considers the following 
shells to be peculiar to this division of the Campsie strata, namely, Pro- 
ductus mesolobus, P. aculeatus, and P. fimbriatus. 
In the West of Scotland the Blackhall Limestone usually presents a 
lower part, which is a brown-crusted entomostracan limestone, and an 
upper part, which is an encrinital limestone with solitary corals. In the 
east the estuarine lower part is absent, and only the upper or marine 
part is developed. Over the limestone comes a dark shale, which carries 
a faunal assemblage which has been traced all over the West of Scotland 
and into Fife and the Lothians. The following are some of the more 
characteristic forms : — Ghonetes hardrensis, Leda brevirostris, Nucula 
luciniformis, Bentalium priscum, D. inornatum, Euomphalus carbon- 
arius , Pleurotomaria conica var. decussata, Bellerophon oldhami, Gonia- 
tites gilbertsoni, G. mucronatus, G. striatus, G. vesica , Nautilus subsul- 
catus, N. biangulatus, Orthoceras cinctum, 0. golclfusianum, and 0. 
pygmaum. Spirifer urei, a shell comparatively rare on other horizons, 
is abundant on this, and its large numbers are usually sufficient to identify 
the horizon at once. Other abundant forms are Loxonema curvilinea and 
Gyrtoceras rugosum. 
The Main Hosie Limestone as developed in the Glasgow district and 
at Bathgate, Charlestown, Seafield, and Skateraw in the East of Scot- 
land, presents a rich faunal assemblage. Amongst other forms we 
have Litliostrotion junceum, Zaphrentis patula, Lonsdaleia floriformis , 
Gyatliopliyllum regium, Aulophyllum fungites, Alveolites depressa, and A. 
sejdosa. The last, besides being found growing in large irregular masses 
in the limestone, frequently occurs on shells such as Productus giganteus, 
of which fine examples are occasionally found. In certain of the localities 
crinoid remains are abundant, belonging to the genera Hydreionocrinus, 
Platycrinus, and Poteriocrinus. The polyzoa are also exceedingly 
abundant upon this horizon, and are represented by the genera Geriopora, 
Biastopora, Fenestella, Glauconome, Polypora, and Rhabclomeson. Some of 
the other common forms are Phillipsia eichwaldi var. mucronata, Pro- 
ductus giganteus , P. youngianus , P. acideatus, Terebratida hastata, the 
three varieties; several species of Aviculopecten, Pinna flabelliformis, P 
spatula, Euomphalus dionysii, large examples of Bentalium ingens , 
Tomodus convexus, Psammodus porosus, and several other palatal teeth. 
In ascending order the next recognisable faunal association is that 
