PALEONTOLOGY ZORRITOS FORMATION 49 



leaves open the possibility that a different systematic posi- 

 tion may be found necessary. The Nassidae are in a bad 

 state as regards the crystallization in the literature of differ- 

 ential characteristics, and the revision that is necessary is 

 naturally without the bounds of this work ; . without such 

 revision the designation of a new unit to receive this shell 

 would only add to> the confusion which now awaits the atten- 

 tion of a reviser. 



The most closely allied species known to the writer is 

 Nassa veneris Fauj., of the ,Burdigalian of the Gironde, 

 France, and the Mediterranean Tertiary, described by Bell- 

 ardi, 42 and later referred by Cossmann 43 to the genus Dor- 

 sanum Gray. Reference to the type of Gray's genus shows 

 that N. veneris probably does not belong to it, and it is ap- 

 parent that -N. zorritensis and .N. veneris are of a sub-group 

 yet to be designated, differing from Nassa chiefly in being 

 strongly keeled, with a distinct shoulder giving a squarish 

 aspect to the upper parts of the whorls and of the aperture. 

 Most of the Nassas have a stronger callus than have the two 

 forms here discussed, and it is probable that that feature will 

 prove a further point of differentiation. 



Variegated Zorritos. South of Quebrada Pantheon. 



Genus TRIUMPHIS Gray 



Triumphis solida (Nelson) 



PLATE II Fig. 3. 

 Clavella solida Nelson, Trans. Conn. Acad., vol. 2, p. 199, 1870. 



Pyrula roscta Grzybowski, Neues Jahrb., Beil. Bd. 12, p. 648, 

 pi. 19, fig. 6, 1899. 



"Shell oval, ventricose, and heavy; spire moderately ele- 

 vated and tapering. Whorls five to seven, more or less 

 depressed above. Sutures distinct. Body whorl large, more 



42 Piemonte, pte. 3, p. 58, pi. 4, figs. 3a, b, 1882. 



43 Essais de Pal. Comp., vol. 4, p. 219, 1901. 



