PLATE XXIII. 
Fig. 1. Perisphtnctes potosinus Castillo and Aguilera (p. 105), 
I'k,. 2. Perisphinctes iiiixi Castillo :iii(l Aguilera (p. 106). 
Fig. •".. Nautilus naufbagus sp. n. (p. 100). 
Sec PI. XXIV, fig. 3. 
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