FOEAMINIFERA OF NORTH PACIFIC OCEAN. 



61 



Genus TRITAXIA Reuss, I860. 



Pextularia (part) Reuss, Verst. Bohm. Kreid., pt. 1, 1845, p. 39. 



Tritaxia Reuss (type, T. tricarinata (Reuss) = Textularia tricarinata Reuss), Sit/,. 



Akad. Wiss. Wien, vol. 40, 1860, p. 228.— H. B. Brady (part), Rep. Voy. 



Challenger, Zoology, vol. 9, 1884, p. 388. 



Description. — Test triserial, at least in the earlier portion, usually 

 triangular in cross section; aperture central and terminal with or 

 without a distinct neck and lip, rounded; wall usually arenaceous. 



Tins genus, as defined by Reuss and employed by Brady, includes 

 those triserial forms which in their earlier development are like Ver- 

 neuilina and have a textularian aperture, later changing their plan 

 of development so that the newly added chamber occupies nearly 

 or quite the whole of the apertural end of the test. With this 

 change in the chamber comes a change in the aperture to a ter- 

 minal position and a corresponding change in shape to a circular 

 opening, usually with a raised lip, and in some species with a definite 

 tubular neck as well. 



A new genus has been erected for T. caperata II. B. Brady, which 

 is in many ways different from other species of Tritaxia. 



TRITAXIA TRICARINATA (Reuss). 



Textularia tricarinata Reuss, Verst. Bohm. Kreid., pt. 1, 1845, p. 39, pi. 8, rig. GO. 



Tritaxia tricarinata Reuss, Sitz. Akad. Wiss. Wien, vol. 40, 1860, p, 228, pi. 12, 

 figs. 1, 2.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 389, 

 pi. 49, figs. 8, 9.— Goes, Bull. Mus. Comp. Zool., vol. 29, 1896, p. 39. 



Description. — Test elongate, triangular in cross section, the edges 

 carinate, the apical end bluntly rounded, the sides slightly concave; 

 apertural aspect triangular; wall rather coarsely arenaceous, fairly 

 smooth, the sutures rather indis- 

 tinct; aperture in adult speci- 

 mens rounded, central, terminal, 

 often with a short neck; color 

 brown. 



Length about 1 mm. 



Distribution. — Goes records 

 this species as rare in the Pacific 

 (referring to the southeastern 

 portion of the North Pacific), in 

 900 fathoms. None of the Pa- 

 cific stations from which Goes 

 had material is exactly 900 fath- 

 oms in depth, although several 

 are near it. Under the lists by stations this species does not occur 

 from the Pacific list, and there are no specimens in the lot returned 

 by Goes. Therefore the record rests solely upon the published work 

 of Goes. 



Figs. 9S-99.— Tritaxia tricarinata. X 35. 



98, a, APERTURAL VIEW (AFTER BRADY). 



