GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 69 



Description. — Test nearly equally biconvex, peripheral margin 

 bluntly rounded; chambers numerous, the sutures oblique, distinct, 

 often limbate ; aperture a narrow slit extending from near the periph- 

 ery nearly to the umbilicus. 



Diameter 0.65 mm. Cat. No. 324666-7, U.S.N.M. 



The only station at which this species occurred is in the upper part 

 of the Culebra formation, U.S.G.S. No. 6019^, upper part of second 

 hard, limy, sandstone bed, Las Cascadas section, Gaillard Cut. It 

 is rather larger than the usual run of T. pygmaea but is evidently 

 this species. 



Specimens from the Gatun formation, U.S.G.S. No. 6036, while 

 having fewer chambers and somewhat larger size are questionably 

 referred here. One specimen is figured on plate 24, figure 2. 



TRUNCATULINA UNGERIANA (d'Orbijmy). 



Plate 24, fig. 1. 



Rotalina ungeriana, d'Okbigny, Poram. Foss. Bass. Tert. Vienne, 184G, p 



157. pi. 8, figs. 36-18. 

 Planorbulina, ungeriana H. B. Bkady. Trans. Linn. Soc. London, vol. 24, 



1864, p. 469, pi. 48, fig. 12. 

 Tnincatulina ungeriana Reuss, Denkschr. Akad. Wiss. Wien, vol. 25, 1865, 



p. 161.— H. B. Beady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 664, 



pi. 94, figs. Qa~d. 



Description. — Test biconvex, dorsal side less convex than the ven- 

 tral ; peripheral margin subacute, slightly carinate, chambers numer- 

 ous, 10 to 12 in the last formed whorl, sutures distinct, slightly lim- 

 bate on the dorsal side; aperture a narrow arched opening running 

 ventrally from the peripheral margin. 



Diameter 0.50 mm. Cat. Nos. 324668-9, U.S.N.M. 



Specimens referable to this species but not entirely typical were 

 obtained in material from lower part of the Culebra formation, as 

 follows: U.S.G.S. No. 6009, from black clays and sandy beds at lower 

 end of Pedro Miguel Locks; and 6012a, from lower dark clay be- 

 neath lower conglomerate, one-fourth mile south of Empire Bridge, 

 west side Gaillard Cut, below Culebra. 



TRUNCATULINA WUELLERSTORFI (Schwager). 

 Plate 24, fig. 3. 



Anomalina wuellerstorft Schwagek, Novara. Exped., geol. Theil., vol. 2, 



1866, p. 258, pi. 7, figs. 105, 107. 

 Truncatulina wuellerstorft, H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 



9, 1884, p. 662, pi. 93, figs. 8, 9. 



Description. — Test plano-convex, dorsal side nearly flat, ventral 

 side slightly convex; chambers numerous, elongate, curved; sutures 



