THE FOMMOIFEEA OF THE ATLANTIC OCEAN. 



CHILOSTOMELLIDAE AND GLOBIGERINIDAE. 



By Joseph Augustine Cushman, 



Of Sharon, Massachusetts. 



INTRODUCTION. 



This fifth part of the worl^ on the Atlantic Foraniinifera deals with 

 the ChilostomeUidae and Globigerinidae. The same arrangement of 

 data as that used in the earher parts is here followed. As most of 

 the species are pelagic at some time in their life history the distribu- 

 tion shows less well-marked faunal areas than in the bottom-living 

 forms. 



SYSTEMATIC PART. 



A systematic presentation of the various groups follows: 

 Family 6. CHILOSTOMELLIDAE. 



Test calcareous, conspicuously punctate, chambers usually some- 

 what inflated, irregularly coiled, the last-formed chamber in the 

 various genera making up a large portion of the last-formed volution; 

 apertiu'e usually a curved opening between the base of the chamber 

 and its predecessor, sometimes terminal. 



This family is represented in the present oceans by three genera, 

 CMlostomella, in which each chamber takes up 180° of the periphery 

 as added; AUomorphina, in which it takes up typically 120°; and 

 Seabrookia, which has a somewhat more definitely coiled appearance. 



As CMlostomella is somewhat alternating in dorsal view, it has been 

 placed near the Textulariidae, but in many ways the family seems 

 nearer the Globigerinidae. 



The family also includes the genus Ellipsoidina Seguenza, which 

 occurs in the later Tertiary, but is not known as a Recent genus. 



Genus CHILOSTOMELLA Reuss, 1850. 



Chilostomella Reuss (type, C. ovoidea Reuss), Denkschr. Akad. Wiss. Wien, 

 vol. 1, 1850, p. 379. — H. B. Brady, Rep. Voy. Challenger, Zoology, 

 vol. 9, 1884, p. 436.— Chapman, The Foraniinifera, 1902, p. 182.— 

 CusHMAN, Bull. 71, U. S. Nat. Mus., pt. 4, 1914, p. 2. 



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