76 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



usually rather coarsely so, and the exterior more or less rough; 

 aperture in the uniserial portion circular, central, partially closed 

 with a broad valvular tooth. 



Length up to 3 mm. 



Distribution. — The only published records for this species from the 



North Pacific are those given by Brady from two Challenger stations, 



one off the Philippines, in 95 fathoms, the other in the deep water of 



the Pacific, in 3,125 fathoms. This latter seems all the more peculiar, 



as the species as a rule has been found in comparatively shallow 



water. 



Subfamily 4. BULIMININ^E. 



Included in this subfamily are those forms which are typified by 

 Bulimina. In typical species the arrangement of the chambers is 

 an elongate spiral. The aperture is elongate, loop-shaped, usually 

 in an oblique position, and in some species there is a tooth, flange, or 

 other structure which partially closes the opening. The test is cal- 

 careous, often hyaline in the young, but may be considerably thick- 

 ened and opaque in the adult; is always perforate. 



Two new genera have been segregated from Bulimina, the differ- 

 ences in structure and development appearing to be worthy of more 

 than specific rank. 



Genus BULIMINA d'Orbigny, 1826. 



Bulimina d'Orbigny (type, Bulimina marginalu d'Orbigny), Ann. Sci. Nat., 

 vol. 7, IS26, p. 269.— H. B Brady (part), Rep. Voy. Challenger, Zoology, 

 vol. 9, 1884, p. 397. 



Description. — Test usually fusiform or tapering, free, composed of 

 numerous chambers arranged typically in a spiral, each chamber 

 situated above the third preceding one, making a triserial arrange- 

 ment, not always visible from the surface except in the last convo- 

 lution; wall calcareous, perforate, usually thin and transparent but 

 thickening somewhat with age; smooth or ornamented with raised 

 costa 1 , spines, etc.; aperture typically a comma-shaped slit broadest 

 above and tapering obliquely to a point below, usually with a raised 

 rim and often partly closed by a tooth-like rim at one side. 



The genus Bulimina as it has come to be used includes several dis- 

 tinct groups of species as noted by Brady in the Challenger report 

 upon the Foraminifera. If these groups are closely examined it will 

 be noted that their differences are really morphological and essential 

 characters, too distinct to be accounted for on the basis of variation 

 and seem to be of generic significance. I have therefore divided the 

 genus into several genera which show distinctive characters, and have 

 limited the name Bulimina to those species which show a triserial 

 arrangement of the chambers. Such an arrangement is seen in the 

 typical Bulimina marginata, the only species figured by d'Orbigny of 

 those given under the genus in the original description. 



