NO. lO AMERICAN SPECIES OF LEPIDOCYCLINA VAUGIIAN 33 



similar to those from the Canal Zone, except that they are smaller. 

 As the enlargement of all the figures is the same, the relative di- 

 mensions are obvious. 



Localities and geologic horison. — The two principal localities for 

 L. vaughani have been given above. In the Canal Zone it is associated 

 with L. canellei. Therefore, the geologic horizon of the two species is 

 the same. Other associated species at Half Moon Bay, Antigua, are 

 L. parvula Cushman and L. undosa Cushman. The occurrence is in 

 the Antigua formation, but apparently not in its basal part. The 

 horizon, therefore, is Oligocene, perhaps upper rather than middle. 



LEPIDOCYCLINA (NEPHROLEPIDINA?) CRASSIMARGO Vaughan, n. sp. 

 Plate 27, figs. I, 2, 3 



This species is based on a number of fragmentary sections, those 

 represented by plate 27, figures 2 and 3, being selected and designated 

 as cotypes. As the section illustrated by figure i, on plate 2^, seems 

 definitely to represent either a young specimen or the central part of 

 the test of the same species as that represented by figure 2 on the same 

 plate, it will be described first. 



Test small, thin, lenticular. Diameter about 3.5 mm, thickness 

 through the center 0.5 mm. Surface smooth or with microscopically 

 minute papillae. 



Embryonic chambers unknown. 



Equatorial chambers known only in vertical section ; height 0.05 to 

 0.06 mm, increase in height toward the periphery slight ; length radially 

 less than the height. The equatorial chambers project beyond the 

 lateral chambers and produce a thin free edge as much as 0.30 mm 

 wide. 



Lateral chambers low, longer than tall, rather regular in size and 

 shape ; those in the same tier separated by thin walls ; between ad- 

 jacent tiers there are in some places very fine, thin pillars. Six or seven 

 layers over the central part of the test. 



The following description is based on the cotypes, illustrated on 

 plate 2y, figures 2, 3 : 



Interior part of test very thin, about 0.25 mm thick; margin ex- 

 panded to a thickness of i.o mm on the edge. The piece here de- 

 scribed and figured is 3.5 mm long, the pronounced expansion begin- 

 ning about 2.5 mm from the periphery. 



Equatorial chambers in the central part about 0.06 mm high and 

 o.io mm long; at the periphery the vertical distance across the 

 equatorial layer is i mm, the chambers may be divided into a few 



