162 STUDIES IN GEOLOGY, No. 3 



sulcus is more prominent. It is also like 7". cibaoica Maury 

 (loc. cit), but is less inflated, shorter, has a more prominent 

 posterior sulcus, and the posterior margin is more blunt. 

 T. aequiterminata Brown and Pilsbry, 187 from Gatun, is also 

 similar, but differs much as it does from T. zapotalensis. 

 T. singewaldi and T. zapotalensis, being closely related, 

 have naturally the same general affinities. T. singewaldi is 

 perhaps nearest to T. papyria Conrad, 188 of the Claiborne 

 Eocene. Comparison with specimens of papyria from Lisbon 

 and Claiborne shows an agreement which is imperfect only 

 in the longer form of papyria. 

 Lower Zorritos. Quebrata Zapotal. 



Family PSAMMOBIIDAE 



Genus TAGELUS Gray 

 Tagelus gibbus (Spengler) 



Solen gibbus Spgl., Skrift. Nat. Selsk., vol. 3, p. 304, 1794. 



Solen guineensis Chemn., Conch. Cab., vol. n, p. 102, pi. 198, fig. 

 1937, 1795; Dilwyn, Descr. Cat., vol. i, p. 62, 1817; Wood, Gen. 

 Conch., p. 129, 1835. 



Solen declivis Turton, Conch. Diet, p. 164, fig. 80, 1819. 



Psammobia declivis Turton, Dithyra Brit., p. 91, 1822. 



Solen caribaeus Lam. An. sans. Vert., vol. 5, p. 454, 1818. 



Siliquaria notata Schum. Essai, p. 129, pi. 7, figs. 2-3, 1817. 



Solecurtus caribaeus, Blainv., Diet. Sc. Nat., vol. 29, p. 240, 1825; 

 Conrad, Am. Mar. Conch., p. 22, pi. 4, fig. 3, 1831 ; Gould, Inv. 

 Mass., p. 30, 1841; Mighels, Bost. Journ. Nat. Hist., vol. 4, p. 312, 

 1845; Sowerby, Conch. Icon., Solecurtus, fig. 2ia, b, 1874. 



Solen adamsonii Bosc., Hist. Nat. Coq., vol. 3, p. 12, 1802. 



Cultellus caribaeus Conrad, Am. Jour. Sc., 2nd ser. vol. i, p. 404, 

 1846; not of Med. Tert, pi. 43, fig. i, 1845. 



Siliquaria gibba H. & A. Adams, Gen. Rec. Moll., vol. 2, p. 347, 

 not p. 93, figs. 5, sa, 1856. 



L87 Proc. Ac. Nat. Sc. Phila., vol. 64, p. 517, pi. 26, fig. 5, 1912. 

 188 Harris, Bull. Amer. Pal., vol. 6, No. 31, p. 159, pi. 49, figs. 7-11, 

 1919. 



