NO. 4 FORAMINIFEKA CUSHMAN 55 



complanate forms consisting of a linear series of pores on the apertural 

 face, in the less compressed forms an irregularly arranged series of 

 pores and in the more or less uncoiled forms often becoming dendritic. 



Genus ORBICULINA Lamarck, 1816 



Plate 16, figs. 2, 3 



Test planospiral, at least in its early stages, the chambers numerous, 

 and in the later stages, at least, subdivided into chamberlets, the early 

 chambers in all forms extending over the early test to the umbilical 

 region, making a completely involute test in the early stages, later 

 chambers may continue the completely involute character, or may be- 

 come annuli or build a crosier-shaped test, wall usually pitted, some- 

 times smooth ; aperture in the adult usually consisting of a double row 

 of small circular openings usually opposite, along the median portion 

 of the apertural face of the test. ■ 



Genus ORBITOLITES Lamarck, 1801 

 Plate 16, fig. I 



Test typically discoidal. the early chambers, in the microspheric 

 form at least, following the proloculum and Coniuspira-like second 

 chamber, arranged in a gradually widening spiral, followed by cham- 

 bers extending in length and becoming annuli ; chambers divided into 

 chamberlets, each with one or more apertures on the rim of the test. 



Genus CRATERITES Heron-Allen and Earland, 1924 



Test apparently sessile or becoming free, with a basal layer of a 

 nubecularine mass of chambers without spiral arrangement, arising 

 from which is a thick trunk, nearly circular in section, composed of 

 superimposed rings of chamberlets, orbitoline in appearance but 

 without marginal pores ; test widest near the top, the upper surface 

 with a thin, highly convex apertural surface, entirely covered with 

 close perforations forming the apertures. 



Genus ALVEOLINA d'Orbigny, 1826 



Plate 15, .figs. 7, 8 



Test usually elliptical or fusiform, composed in the adult of 

 elongate chambers, each running the entire length of the test, the 

 apertural face of the last-formed chamber forming the growing edge 

 of the test ; chambers divided into chamberlets with small circular 

 apertures upon the apertural face, at least in the larger species ; whole 

 test spirally coiled about the elongate axis. 



