348 FORAMINIFERA 



similar to the equatorial chambers of Orbitoides. The equatorial 

 chambers communicate with the chambers of the same ring and 

 with those of the adjacent rings through apertures at the cham- 

 ber corners by means of stolons. The roofs of the chambers are 

 minutely cribriform. Lateral chambers well developed, their 

 roofs minutely perforate, communication also through apertures 

 at the chamber ends. Pillars and papillae or pustules variable 

 in development. They may have their origin at the surface of 

 the equatorial chamber or between the ends of the lateral cham- 

 bers. 



Upper Eocene to lower Miocene. 



The apertures and perforations of Lepidocyclina have not 

 been studied with nearly sufficient thoroughness. Sections of 

 Lepidocyclina in the equatorial plane show that the inner ends 

 of the side walls of chambers in the same ring do not in every 

 instance reach the outer wall of the ring against which they 

 abut, and there may be similar openings between the chambers 

 of one ring and those in the next beyond. These openings rep- 

 resent passages that lead from one chamber to another in the 

 same ring and from the chambers in one ring to those of the 

 next outer ring. In a vertical section of a well preserved speci- 

 men, the surfaces of the radial chamber walls can be examined 

 and end views of the apertures obtained. They may also be seen 

 on the edges of some specimens by looking along a line perpen- 

 dicular to the periphery. These openings or passages are differ- 

 ent from the minute cribriform perforations. Hofker called the 

 larger openings "foramina", and the cribriform perforations 

 "pores", a nomenclature of more than doubtful validity (aee 

 Century Dictionary, under foraminifera) . I shall for pres- 

 ent purposes call the larger openings, apertures or passages; 

 and the smaller ones, cribriform perforations. 



In many, if not most species of Lepidocyclina, the equatorial 

 chambers communicate with the lateral chambers only by means 

 of cribriform perforations in the chamber roofs. Those in L. 

 mortoni Cushman are from 1 to 1.5 ii in diameter. In some 

 species the roof of the equatorial chamber appears to bend down- 

 ward and form the front or external wall of the chamber. Where 

 this occurs there may be a passage leading from the equatorial 

 layer to the adjacent lateral layer. This seems to be the case in 

 L. r. "doiivillH Lisson and L. gigas Cushman. 



