FORAMINIFEBA OF THE NORTH PACIFIC OCEAN. 17 



spire or variously compressed; wall smooth, sutures depressed, punc- 

 tate; aperture consisting of a series of rounded or elliptical pores at 

 the junction of the last formed chamber with the next preceding 

 chambers. 



Diameter of test averaging about 0.75 mm. 



Distribution. — Brady records this species from a single North 

 Pacific station in the Challenger Report, the depth given being 214- 

 500 fathoms. Bagg records it off the Hawaiian Islands at seventeen 

 Albatross stations, the depths ranging from 104-1,544 fathoms. I 

 have had numerous specimens of this species from a large number 

 of stations about the Hawaiian Islands, off Guam, between Guam 

 and Yokohama, and between Guam and Midway Island. It has 

 never occurred in any great numbers. The depths range from 392- 

 2,615 fathoms with the average at about a thousand fathoms. 



This species is easily distinguished by its Globigerina-like form and 

 its very characteristic apertural openings. It was found by Millett 

 in material from the Malay Archipelago and by Brady in the South 

 Pacific and the regions of the West Indies and various parts of the 

 Atlantic. D'Orbigny's original specimens came from the shore sands 

 of the West Indies, Cuba, and Jamaica. 



This species is one of the small number that occur as pelagic forms. 

 The Challenger obtained specimens from tow nets in the North Pacific 

 and also in the South Atlantic. 



Genus SPH^EROIDINA d'Orbigny, 1826. 



Sphaeroidina d'Orbigny (type, S. bulloides d'Orbigny), Ann. Sci. Nat., vol. 7, 

 1826, p. 267.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, 

 p. 619. 



Description. — Test composed of a small number of chambers ar- 

 ranged in a short spire, the chambers inflated and increasing rapidly 

 in size and embracing, few only visible from the exterior; wall per- 

 forate ; aperture an arched opening at or near the inner margin of the 

 chamber, often with a calcareous tooth-like process partially closing 

 the opening. 



One of the species, S. dehiscens, occurs in the pelagic condition and 

 is especially modified in various ways as are a number of pelagic 

 species. 



This genus is found in some numbers in the later Tertiary, but 

 earlier than this does not seem to be at all common. 



Various synonyms appear, such as Sexloculina Czjzek, and Gram- 

 mobotrgs, and Bolbodium of Ehrenberg. 



