PALEONTOLOGY ZORRITOS FORMATION 141 



His figured hinge agrees absolutely with that of the Peruvian 

 specimens. It is obvious that Toula's form is not D. aceta- 

 buluni Conrad ; as noted by Brown and Pilsbry, there is 

 decided difference in sculpture, and acetabulum is a heavier 

 shell. Toula's comparison with D. orbicularis Agassiz, 157 

 from the Oligocene to Pliocene of Italy, France, and Austria, 

 is apt as far as the surface sculpture and general shape are 

 concerned, but the European form is much thicker and 

 heavier, has deeply impressed muscle scars, is posteriorly 

 truncate, and the beaks are far more forward in position. 

 D. (Dosinidia) liogona Ball, 158 "from the Oak Grove beds of 

 Florida, is similar. As noted by Brown and Pilsbry (loc. 

 cit.), the sculpture of delicatissima does not rise in sharp 

 lamellae toward the end of the shell, as in liogona; otherwise 

 the likeness is marked. The hinge does not agree with that 

 of liogona in that the anterior cardinal is not as strong, and 

 is of different shape. The entire hinge of delicatissima is 

 not as broad and heavy as that of liogona. 



Lower Zorritos. Head of Quebrada Zapotal. 



Genus CLEMENTIA Gray 



dementia dariena (Conrad) 



PLATE VIII Fig. 5. 



Meretrix dariena Conrad, Pac. R. R. Rept, vol. 5, p. 328, pi.. 6, 

 % 55, 1856, (not op. cit. vol. 6, p. 72, 1857). 



Harvella sp. ind. Nelson, Trans. Conn. Acad., vol. 2, p. 201, 1870. 



dementia dariena Gabb, Jour. Acad. Nat. Sci. Phila., vol. 8, p. 

 344, pi. 44, figs. 16, i6a, 1881. 



Clementia dariena Ball, Trans. Wag. Inst., vol. 3, pt. 6, p. 1235, 

 1903. 



157 Hoernes, M., Abh. kk. geol. Reichs. Bd. 4, p. 142, p. 16, tig. I, 

 1870; Sacco, Piemonte, pte. 28, p. 48, pi. n, fig. 10, 1900. 



158 Trans. Wag. Inst., vol. 3, pt. 6, p. 1230, p. 53, figs. 4, 7; pi. 

 54, figs. 11, 1903. 



