rORAMINIFERA OF THE ATLANTIC OCEAN. 101 



Genus CRISTELLARIA Lamarck, 1812. 



Nautilus (part) Linnaeus, Syst. Nat, ed. 12, 17G7, p. 1162. 



LenticnUtes (part) LAjrAEcK, Annales du Museum, vol. 5, 1804, p. 188. 



Cristellaria Lamarck (type, C calcar (Linnaeus)), Extrait Cours Zool., 

 1812, p. 122.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 

 1884, p. 534.— CHAPiiAN, The Foraminifera, 1902, p. 193.— Cushman, 

 Bull. 71, U. S. Nat. Mus., pt. 3, 1913, p. 63. 



Description. — Test planospiral, typically close-coiled, but becom- 

 ing much uncoiled in some species ; chambers numerous ; wall hyaline, 

 perforate, variously ornamented ; aperture usually distinctly radiate. 



Typically this genus is close-coiled throughout, but various species 

 are included under it in which the later chambers become uncoiled. 

 It is often a question whether these species should be referred to 

 Cristellaria or to Marginulina. Often in the uncoiled portion of 

 such species the sutures between the chambers are oblique. There 

 is great range of variation in the ornamentation of the test, which 

 may be smooth or costate, the costae often breaking up into knobs 

 and bosses, spines, or combinations of these, the sutures being fre- 

 quently limbate, and the periphery often with a broad keel or orna- 

 mented by a series of spines. The aperture is almost always radiate, 

 and in some species the apertures of the preceding chambers are 

 visible, giving a peculiar appearance to such specimens. 



The genus is recorded as far back as the Cambrian and is very 

 abundant in the Cretaceous and in certain portions of the Tertiaiy. 

 In the present oceans it is widely distributed, both geographically 

 and bathymetrically. It reaches a very great development, espe- 

 cially in the number of species, in tropical waters from 100-500 

 fathoms (183-914 meters) in depth, and in cold waters of similar 

 depths, while the species are not so numerous, specimens are often 

 very abundant. The greatest ornamentation is seen in tropical 

 species. 



CRISTELLARIA ORBICULARIS (D'Orbiffny) 7 



Plate 21, fig. 7. 



Brady records this species from off Sombrero Island, West Indies, 

 450 fathoms (823 meters) and had several stations in the South 

 Pacific. I have specimens from a single Albatross station off the 

 coast of Georgia, one which is here figured and is apparently similar 

 to the form which Brady had from the West Indies. Flint records 

 it from the Gulf of Mexico, 169 and 210 fathoms (308 and 384 

 meters). There are numerous other records for the species, all 

 from the Indo-Pacific. It is therefore to be doubted whether this 

 species is really identical with that described by D'Orbigny from 

 tlie Tertiary of Central Italy. 



