PALEONTOLOGY ZORRITOS FORMATION 73 



Turrit ella inca Grzybowski 



Turritella inca Grzybowski, Neues Jahrb. f. Min., etc., Beil. Bd. 

 12, p. 644, pi. 20, fig. i, 1899. 



"Umgange convex, etwas zweikantig. Die 4 untersten 

 Spiralleistchen sehr schwach angedeutet, dicht beieinander 

 liegend, die fiinfte und siebente Rippen sind die starksten; 

 sie bilden zwei Kanten, die ein flaches, in der Mitte mit 

 schwachen Leiste versehenes Band umgrenzen. Es folgen 

 gegen oben noch 5 ziemlich starke, gleiche Spiralleistchen. 

 Die hohe des der Spitze entbehrenden Bruchstiickes 90 

 mm, Dicke und der Miinding 22 mm., oben 6 mm. Die 

 totale Lange mochte bis 115 mm. betragen." Grzybowski, 

 1899. 



This species does not occur in the Hopkins or Nelson 

 collections, but it is mentioned here to complete the group 

 of which it is an end member. Grzybowski has pointed out 

 its similarity to varieties of T. triplicate* Sacco, from the 

 Miocene of Italy. It is closer to T. gatunensis Conrad G5 

 from the Gatun Miocene. The only notable difference be- 

 tween the two lies in the apparently sharper early whorls of 

 gatunensis, and a heavier thread above the band, together 

 with the lack of the thread on the band mentioned and fig- 

 ured by Grzybowski ; but the figure of inca is poor, and com- 

 parison of material might reveal specific identity. 



Upper Zorritos or Variegated. Pantheon at Zorritos. 



Turritella inca var. trita n. var. 

 PLATE III Fig. 4. 



Shell much as in T. inca, with the following characteristic 

 differences: The upper carina barely noticeable instead of 

 prominent; the band almost smooth, bearing one subsidiary 

 thread near the anterior carina ; above the band are only two 



85 Brown and Pilsbry, Proc. Ac. Nat. Sc. Phila., vol. 63, p. 358, 

 pi. 27, fig. 4, 5, 9, 1911. 



