GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 55 



Description. — Test much compressed, composed of numerous cham- 

 bers about twice as broad as high, sutures distinct, slightly curved 

 backward, chambers slightly inflated, especially in the center, test 

 bordered by a narrow but distinct carina ; surface smooth except for 

 several longitudinal raised costae radiating from the initial end which 

 carries also a short spine. 



Length 0.65 mnL, breadth 0.35 mm. Cat. No. 324617a, b, U.S.N.M. 



A few specimens were obtained from U.S.G.S. No. 6033c, Gatun 

 formation, in marl from second bed from bottom, just below lower 

 clay, Gatun section, relocated line, Panama Railroad. 



While these specimens are not absolutely typical they undoubtedly 

 belong to this species. 



Very tj^pical specimens occur at U.S.G.S. No. 6036, Gatun forma- 

 tion, in dark colored, fine grained, sandy clay marl, from Monkey 

 Hill, Mount Hope Station. 



BOLIVINA ROBUSTA H. B. Brady. 



Plate 21, fig. 4. 



Bolivina robusta H. B. Beady, Quart. Journ. Micr. Sci., vol. 21, 1881, p. 

 57; Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 421, pi. 53, figs. 7-9. 



Description. — Test compressed, gradually tapering toward the 

 apical end; chambers comparatively few; about twice as broad as 

 high; sutures limbate, gently curved backward, often slightly lobu- 

 lated or occasionally showing traces of reticulation on the surface, 

 wall otherwise smooth but punctate, not spinose at the apical end. 



Length 0.45 mm., breadth 0.25 mm. Cat. No. 324618, U.S.N.M. 



These specimens, an extreme form of which is figured, are many of 

 them very close to typical B. robusta which is at best either a variable 

 species or one including more than one form. The sutures are 

 usually limbate, as shown in some of Brady's figures, but no apical 

 spine is apparently in any of the specimens in this material. They 

 were from U.S.G.S. No. 6035, Gatun formation, from gray green, 

 fine grained, sandy shell marl, vicinity of Mindi Hill. 



BOLIVINA, species? 



Plate 21, fig. 1. 



This specimen is rather ill-defined and cannot be definitely deter- 

 mined from the single example, the sutures are limbate as in Bo- 

 livina robusta Brady, but have apparently no secondary extensions 

 as in that species. The whole specimen seems to be replaced. The 

 specimen is from U.S.G.S. 6010, lower part of the Culebra formation, 

 from dark clav north of Pedro Miguel Locks. Cat. No. 324619, 

 U.S.N.M. 



