Paleontology Zorritos Formation" 155 



original description, C. balUsta Dall/'^ from the Tampa 

 silex beds, has less numerous, occasionally ventrally striated 

 ribs that are attenuated above to the dorsal margin. The 

 Oak Grove C. glyptocyma Dall ^"^ resembles the less convex 

 race, but it has a less excavated anterior margin, ribs that 

 are ventrally striated and the point of reduction of the ribs 

 is nearer the escutcheon. The recent C. paphia (Lin- 

 naeus)^'" has a similar appearance, but reaches a larger size 

 and has a more arcuate base and more closely appressed 

 ribs." 



The Zorritos forms of C. hcndcrsonii are distinctly larger 

 than those of the Antilles, and have the lunule constantly 

 somewhat less impressed, but they agree well enough with 

 the Bowden specimens to be regarded as the same species. 

 Unfortunately, they are not sufficiently well preserved to 

 determine the closeness in agreement of the posterior change 

 in the lirae, but all indications available point toward a 

 similarity in this respect as well as in others. Length, 34; 

 height 32; diameter, 16 mm. One large specimen, im- 

 perfect, is 40 mm. long. 



Lower Zorritos. Quebrada Heath. 



Chione ( Lirophora) latilirata (Conrad) 



Venus paphia Lamarck, An. Sans Vert., vol. 5. p. 608, No. 2, 1818; 

 (not Linnaeus, 1767) . 



Venus alveata Say, Am. Conch., vol. 7, pi. 63. 1833; (not Con- 

 rad, 1831). 



Venus latilirata Conrad, Proc. Ac. Nat. Sc. Phila., vol. i. p. 28, 

 1841 ; Fos. Med. Tert., p. 88, pi. 38. fig- 3. 1845. 



Venus vnricosa Sowerby. Thes. Conch., vol. 2. p. 725, pi. 155, 

 fig. 67, 1853; Dall, Bull. U. S. Nat. Mus., No. 7,7, P- 54, 1869. 



'"Trans. Wag. Inst., vol. 3, pt. 6. p. 1295, pi. 55, fig. 23, 1903. 

 "'Idem., p. 1296, pi. 55, fig. 21. 



*"Syst. Nat. ed. 12, p. 1129, 1767; Reeve, Conch. Icon., vol. 14, 

 Venus, pi. 19, fig. 89, 1863; (as ]'enus paphia). 



