•)0' 



Fig. 136. Atrypa reticularis. Interior of brachial and pedicle valves : ventral i pedicle), 

 dorsal (brachial), and lateral views of the exterior of a specimen : \iews of iiiteriDr, with 

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

 of the spiral lirachidia (from Hall). 



Atrypa spixosa. Hall. (Fio-. 137.) (Pal. N. Y., Vol. 

 IV., p. 822, PL LIII.A. ) ( = .4. nspern. of American authors. ) 



Distinguishing Characters. — Greater equality oi valves, 

 which are, in some si)ecimens, almost ec^ually convex; coarse 



^ -^ 



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

 lost its spines (from Hall). 



