210 
PROFESSOR T. J. JEHU AND DR ROBERT CAMPBELL ON 
Series and in the Aberfoyle limestone of the Upper (Margie) Series, and the con- 
sequent more definite determination of the age of the beds ; (c) the recognition of 
spilitic lavas and intrusive albite diabases in the Lower Series and of albite gabbros 
associated with the serpentines ; id) the identification of the rocks of the horn- 
blende-schist complex as metamorphosed representatives of the igneous and sedi- 
mentary rocks of the Lower (Black Shale and Chert) Series. 
We wish also to express our thanks to Dr Peach for the interest he has taken in 
our investigations, for many valuable suggestions, and particularly for his assist- 
ance in the determination of the fossils ; to Dr Flett for the opportunities he has 
given us of comparing our rocks with similar rocks from other districts ; and 
to Mr Cuthbert Day for the trouble which he has taken in connection with the 
photographic illustrations. 
Grateful acknowledgment must also be made to the Carnegie. Trust for a 
grant to defray the expenses incurred in the preparation and reproduction of the 
illustrations. 
XV. EXPLANATION OF PLATES. 
Plate I. 
Acrotliele ( Obolella ) maculata , Salter. 
Fig. 1. Interior of dorsal valve ; distorted. 
Fig. 2. Exterior of the dorsal valve with the ventral valve appearing from underneath. (See p. 189.) 
[T. 2690 D , Geological Survey Collection.] Inset — d = dorsal valve; v = ventral valve. 
Fig. 3. Interior of ventral valve. 
Acrothele aff. coriacese, Linn. (See p. 190.) 
Fig. 4. Exterior of ventral valve. Inset — part of surface much enlarged, showing the external 
ornamentation. 
Acrothele ( Redlichella ) granulata, Linn. (See p. 190.) 
Fig. 5. Exterior of ventral valve. Inset — part of surface much enlarged, showing the external ornamenta- 
tion. Radiolaria are seen in the matrix of the rock. (See p. 187.) 
Acrotreta nicholsoni, Dav. (See p. 190.) 
Fig. 6. Interior of both valves. 
Fig. 7. Exterior of ventral valve. Radiolaria are seen in the matrix of the rock. (See p. 187.) 
Fig. 8. Exterior of ventral valve. 
Fig. 9. Interior of ventral valve. 
Fig. 10. Exterior of ventral valve. 
Fig. 11. Interior of dorsal valve; wrinkled. Radiolaria are seen in the matrix of the rock. 
-Fig. 12. Exterior of ventral valve and interior of dorsal valve. 
Acrotreta socialis, von Seebach. 
Fig. 13. ? Cast of interior of ventral valve. Radiolaria showing spines radiating from centre 
(See p. 187.) 
Fig. 14. Interior of dorsal valve. (See p. 190.) [T. 2621 D , Geological Survey Collection.] 
Fig. 15. Interior of ventral valve. (See p. 190.) 
Acrotreta aff. sabrinx, Calloway. 
Fig. 16. Interior of dorsal valve. (See p. 190.) 
Siphonotreta aff. micula, M‘Coy. (See p. 191.) 
Fig. 17. Exterior of ventral valve. 
Fig. 17a. Drawing (enlarged) of above. 
