PLATE XIII. 
Figs. 1, 2. Cyprina streeruvitzii Cragin (p 78). 
Fig. 'X Lucina planiuscula sp. n. (p. 7~>). 
Figs. A, 5. Lucina potosina Castillo and Aguilera (p. 72 ). 
Figs. 6-10. Lucina potosina var. metrics var. n. (p. 73). 
Figs. 11, 12. Cyprina coteroi Castillo and Aguilera (p. 77). 
Fig. 13. Tapes cuneovatus sp. n. (p. 7'.)). 
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