FAMILY 37. CASSIDULINIDAE 289 



large rounded pores on the outer face, the test at this stage 

 becoming pelagic. 



Recent. 



This family evidently developed from a form close to Discorbis 

 and has adopted the alternating annular series of chambers 

 about the periphery with numerous apertures. In Tretomphalus, 

 there is a very interesting adult development fitting the test 

 for the pelagic life of the animal at this stage. See Earland, 

 On Cymbalopora bulloides (d'Orbigny) and its internal struc- 

 tures, (Journ. Quekett Micr. Club, ser. 2, vol. 8, No. 51, 1902, pp. 

 309-322, pi. 16). 



FAMILY 37. CASSIDULINIDAE 



Test at least in the early stages, trochoid, later chambers in 

 some genera alternating on the dorsal and ventral surfaces of 

 the test or even uncoiling; wall calcareous, perforate; aperture 

 in the early stages of the simpler genera at the margin of the 

 ventral face of the chamber but projecting into the apertural 

 face in a direction gradually becoming parallel to the periphery, 

 elongate. 



KEY TO THE GENERA 



I. Test trochoid throughout. 



A. Aperture opening- into the umbilicus, covered by a thin plate. 



Cer'atobulimina. 



B. Aperture not opening into the umbilicus, not covered by a plate, 



nearly in the plane of coiling Pulvinulinella. 



II. Test biserial, at least in the early stages. 



A. Close coiled throughout Cassidulina. 



B. Uncoiling in the adult 



1. Not compressed, chambers irregular, sutures not depressed. 



Ortfiojjlecta. 



2. Rounded or compressed. 



a. Chambers rounded in section, sutures depressed, test not 

 spinose Cassidulinoides. 



h. Chambers triangular or rhomboid in section, sutures de- 

 pressed, test usually spinose Ehrenhergina. 



Subfamily 1. Ceratobulimininae 

 Test rotaliform throughout. 



