232 



MANUAL OF THE MOLLUSCA. 



that he has found traces of very slender spiral lamellae occupying the furrows. 

 This curious little shell most resembles the Triassic Leptcsna dicbia (Pro- 

 ducta) Miiuster (= Crania Miirchisoiii, Klipst. 1) 

 Davidsonia, B ti chard. 



Dedicated to the author of the ^Monograph of British Possil Brachiopoda. 



Ti/pe, D. Verneuili, Bouch, Fig. 151. Devonian, Eitel. 



Fig. 151. Dorsal valve. Ventral valve, ^. 



Shell solid, attached by outer surface of the ventral valve to rocks, shells, 

 and corals ; valves plain, articulated ; ventral valve with a wide area {Ji) ; 

 foramen angular, covered by a convex deltidium {d): disk occupied by two co- 

 nical elevations, obscurely grooved hy a spiral furrow of 5-6 volutions ; dorsal 

 valve with two shallow lateral cavities ; vascular impressions consisting of 

 two principal sub -marginal trunks, in each valve, with diverging branches; 

 cardinal and adductor impressions distinct. The furrowed cones undoubtedly 

 indicate the existence of spiral arras, similar to those of Atrypa (fig. 144), 

 but destitute of calcified supports. The mantle-lobes seem to have conti- 

 nued depositing shell until the internal cavity was reduced to the smallest 

 possible limit. 



Fig. 152. Dorsal valve. Ventral valve. 



? Calceola, Lamarck. 

 Mpn. Calceola, a slipper. Ti/pe, C. saudalina, PI. XV. fig. 26. Fig. 152. 

 5//^i7 thick, triangular ; valves plain, not articulated : z;,?njtm/ valve pyra- 

 midal ; area large, flat, triangular, with an obscure central line ; hiuge-lin^ 

 straight, crenulated, dorsal valve flat, semi-circular, with a narrow area (A), 

 a small cardinal process (j), and two lateral groups of small apophysary (?) 

 ridges {b) ; internal surface puuctate-striate. Fossil, Devonian, Eifel, Brit. 



