227 





Fig. 136. Atrypa reticularis. Interior of brachial and pedicle valves ; ventral (pedicle), 

 dorsal (brachial), and lateral views of the exterior of a specimen ; views of interior, with 

 pedicle valve removed, with brachial valve removed, showing the position and characters 

 of the spiral brachidia (from Hall). 



Atrypa spinosa. Hall. (Fig. 137.) (Pal. N. Y., Vol. 

 IV., p. 322, PI. LIII.A.) (= A. aspera of American authors. ) 



Distinguishing Characters. — Greater equality of valves, 

 which are, in some specimens, almost equally convex; coarse 



Fig. 137. Atrypa spinosa. Dorsal, ventral, and profile views of a specimen which has 

 lost its spines (from Hall). 



