l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 89 



The embryonic apparatus of the megalospheric form (pi. i, fig. 10) 

 consists of a globular chamber about 140 /a in diameter, followed 

 by a crescent-shaped chamber about 70 to 140 ja in diameter. The 

 division of the chambers into chamberlets begins in the fourth 

 chamber. 



The microspheric form resembles very closely the megalospheric 

 form, having the same number of whorls and the same surface orna- 

 mentation ; however, its thickness through the center is as much as 

 1.25 mm. A horizontal section (pi. i, fig. 11) shows the embryonic 

 apparatus to be of the same type as the megalospheric form, though 

 only about half as large. The first chamber has a diameter of about 

 75 /x ; the second about 40 by 90 fi, followed by four unsubdivided 

 chambers ; the chambers following are subdivided. 



Localities and geologic horizon. — Locality 4. This species is as- 

 sociated with L. {Lepidocyclina) canellei Douville, L. {Nephro- 

 lepidina) undosa Cushman, Miogypsina hazvkinsi Hodson, and 

 Amphisfegiiia lessonii d'Orbigny in the San Luis limestone, middle 

 Oligocene. 



These specimens differ in no significant characteristics from speci- 

 mens of Heterostegina collected by Vaughan and McDonald from 

 the " Culebra " formation, U.S.G.S. station 6025, south end of Bohio 

 Ridge switch, Panama Railroad, Panama, and mentioned by Vaughan 

 (46, p. 789). 



Family PENEROPLIDAE 



Genus ARCHAIAS Montfort 



ARCHAIAS sp. 



Plate 2, fig. I 



A few specimens of this genus were found in thin sections of 

 limestone from localities 1123, and 1206, middle Oligocene, collected 

 by H. G. Kugler. They appear to be very close to, if not identical 

 with, the recent specimens of Archaias adnncus (Fichtel and Moll). 

 Plate 2, figure i, is a horizontal section of a specimen having a 

 diameter of about 1.4 mm. 



These specimens are associated with Gypsina globulus Reuss, 

 Camcrina sp. indet., and Miogypsina hazvkinsi Hodson. 



Genus AMPHISORUS Ehrenberg 

 Amphisorus? sp. 



, Test thin, disklike ; diameter up to about 8 mm. Horizontal sec- 

 tions show the median chambers to be almost circular, about 40 /x in 



