FAMILY 45. ORBITOIDIDAE 349 



The passages between chambers in the equatorial layer vary 

 in the number in a row and the size from species to species. The 

 largest that I have studied are in L. (Polylepidina) chiapasensis 

 Vaughan, in which they are from 30 to 38 ^i in diameter, and 

 there are three in a row in a chamber 210 [i high. These pas- 

 sages are of the same size as those of Orbitoides sp. cf. O. media 

 from India. The next in size are the apertures of L. (Polylepi- 

 dina) p7'oteiformis Vaughan, in which they are 23 to 30 \i in 

 diameter, one in a chamber 110 ^i tall, and 2 in a row in a cham- 

 ber 160 \x tall. In the size of the passages, as well as in the form 

 of the chambers, Polylepidina is very similar to Orbitoides. The 

 size of the apertures grades to smaller sizes. In L. miraflorensis 

 they are only about 10 [i in diameter and there are about 6 in a 

 row in a chamber 120 ^ high. 



In most of the species of Lepidocyclina that I have examined, 

 vertical sections of the equatorial layer show pectinate processes 

 on the distal side of the outer chamber walls, and they may be 

 seen on the broken edges of some specimens as ridges transverse 

 to the outer faces of the chamber and parallel to the equatorial 

 plane. Do these processes bear any relation to the passages be- 

 tween chambers or to the cribriform perforations? In somt. 

 species it seems clear that they do not, but this is not established 

 for other species. In L. gigas Cushman, processes become more 

 or less incorporated in the chamber roofs, which seem to bend 

 downward and form the outer chamber walls, and in places 

 there also seem to be passages from the equatorial to the ad- 

 jacent lateral chambers. 



Is the communication between the equatorial chambers only 

 by means of stoloniferous passages? In some species no other 

 communication could be found, L. mortoni Cushman and L. 

 supera (Conrad) for example. In other species, however, it ap- 

 pears that both means of communication may be present in the 

 same species, but it is not yet established that such is really the 

 case. Doubt regarding many of the structural features of speci- 

 mens is due to changes that have resulted from fossilization. 

 Some features may become concealed, while deceptive appear- 

 ances may be produced. 



This statement is made to indicate certain features of the 

 orbitoids on which much more research is needed. 



