PLATE II. 



FIG. 1. Acrothyra signata mut. tarda, 2i x 3 x \\ mm. Mag. \ 9 ; a Ventral ralve 

 from above ; b Mould of interior of a ventral ; c Same seen from behind ; 

 d Ventral valve from the side. From Assise E. lei (Lower Etchemin. ) 

 at Dugald brook, Escasonie, N. S. See p. 89. 



FIG. 2. Acrothvra proavia, 2 x 1| x f mm. Mag. V '> a Ventral valve ; b Same from 

 behind ; c Same from side ; d Dorsal valve ; e Mould of the inside of this 

 valve ; /Dorsal from the side ; g Outline of the two valves, from the side. 

 From Assise E.3c (Upper Etchemin.) at Dugald brook, Escasonie, N. S. See 

 p. 90. 



FIG. 3. A. proavia, large valves, 3 x 2J x f mm. Mag. 'j 9 ; a Ventral valve ; -6 

 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 3c, lower part, (Upper Etchemin. ) at Dugald brook, Escasonie, N. S. See 

 p. 90. 



Fio. 4. A. proavia, mut, prima, 3 x 2 x 1 mm. Mag. V ; aVentral valve ; 6 Mould 

 of interior c Ventral, from the side ; d Dorsal valve ; e Mould of interior ; 

 /Dorsal from the side. From Assise E. 3a (Upper Etchemin.) at Dugald 

 brook, Escasonie, N.S. See p. 93. 



A. provm, mut. crassa, 2^ x 2 x 2 li mm. Mag.y ; a Ventral valve ;l Mould 

 of same ; c Ventral from the side. From Assise E. 3e, lower part, (Upper 

 Etchemin.) Dugald brook, Escasonie, N. S. See p. 94. 



