THE FORAMINIFERA OF THE ATLANTIC 



OCEAN. 



TEXTULARIIDAE. 



By Joseph Augustine Cusuman, 



0/ the Boston Society of Natural History. 



INTRODUCTION. 



This third part of the work on the Atlantic Foraminifera deals 

 entirely with the Textulariidae, a family allied to the Astrorhizidae, 

 which took up Part 1 of this work, and the Lituolidae, which took 

 up Part 2, in that the test in numerous genera is made up of foreign 

 material, sand grains, etc. The same arrangement of data is fol- 

 lowed as in Parts 1 and 2. The classification is that adopted in 

 Part 1 of my work on the North Pacific Foraminifera. The dis- 

 tribution of various species still further emphasizes the faunal areas 

 developed in the western Atlantic and their relation to the Indo- 

 Pacific. Many of these species recorded in this part are evidently 

 limited in their distribution to the western Atlantic. 



SYSTEMATIC PART. 



A systematic presentation of the various groups of the family 

 follows : 



Family 4. TEXTULARIIDAE. 



Test either arenaceous or calcareous, perforate, the chambers 

 usually numerous, typically biserial or triserial, or in some genera 

 spirally arranged. 



The family Textulariidae is apparently more primitive than most 

 of the other families of the Foraminifera and seems to naturally 

 follow the Lituolidae in its general characters. A number of the 

 simpler genera are wholly or in part composed of species with arena- 

 ceous tests, and this in itself is a primitive character. Many species 

 are known in both microspheric and megalospheric forms, the former, 

 as in other groups, repeating more of the phylogenetic characters 

 than are seen in the megalospheric form. In many species of vari- 

 ous genera the microspheric form shows a coiled early development, 

 following the proloculum, and this may be taken as the primitive 

 character for the whole group. This coiled stage may be compared 



1 



