422 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
Fig. 2. Acrothyra lyroavia^ 2 x x | mm. Mag. ^ 5 — Ventral 
valve ; — h Same from behind ; — c Same from the side ; 
— d Dorsal valve ; . — e Mould of the inside of this valve ; 
— -f Dorsal from the side ; — g Outline of the two valv’es, 
from the side. From Assise E.3c (Upper Ktchemin.) at 
Dugald Brook, Escasonie, N. S. See p. 386. 
Fig. 3. .1. proavia, large valves, 3 x 2| x J mm. Mag. , — a Ven- 
tral valve ; — b Another ventral with corrugated front ; 
— c Ventral from the side ; — d Dorsal ; — e Mould of 
interior of the dorsal ; — /Dorsal valve in profile. From 
Assise E 3e, lower part, (Upper Etchemin.) at Dugald 
Brook, Escasonie, N. S. See p. 387. 
Fig. 4, A. proavia, mut. prima, n. mut., 3 x 2 x 1 J mm. Mag. Y 1 ^ 
Ventral valve ; — h Mould of interior ; — c Ventral, from 
the side ; — d Dorsal valve ; — e Mould of interior ; — f 
Dorsal from the side. From Assise E.3« (Upper Etchemin.) 
at Dugald Brook, Escasonie, N. S. See p. 389. 
Fig. 5. A. proavia, mut. crassa, n. mut., 2-^ x 2 x mm. Mag. 
— a Ventral valve ; — b Mould of same ; — c Ventral from 
the side. From Assise E.3e, lower part, (Upper Etchemin.) 
Dugald Brook, Escasonie, N. S. See p. 389. 
Plate XV. 
Fig. 1. Acrotreta papillata, n. sp., 24 x 2^ x 1^ mm. ]\lag. i/; — a 
A narrow ventral valve ; — b Same from the side ; — c 
Mould of interior of a ventral valve ; — d Dorsal valve ; 
— e Same from the side; — Mould of interior. From 
Assise E. Icf (Lower Etchemin.) at Boundary Brook, Esca- 
sonie, N. S. See p. 390. 
Fig. 2. A. papillata, mut. prima, 2 x 2^ x 1| mm. Mag. ; — a 
Ventral valve ; — b Same, side view ; — c Mould of ven- 
tral. From the Cold brook Group, Dugald Brook, Esca- 
sonie, N. S. See p. 391. 
Fig. 3. A. papillata var. lata, n. var., 2 x 2^ x mm. Mag. tj-®; — a 
Ventral mould of interior ; — b Same froiu the side ; — c 
Same from behind. From Assise E.lc? (Lower Etchemin.) 
at Boundary Brook, Escasonie, N. S. See p. 391. 
