FOEAMINIFERA OF NORTH PACIFIC OCEAN. 



57 



ber with many circular or roughly polygonal openings which ramify 

 into the canals leading to the surface; wall of the central chamber 

 and canals firmer than the rest of the test, usually showing in these 

 firmer portions a reddish-brown cement; color dark grayish brown. 



Diameter 3-6 mm. 



Distribution. — Specimens of this species were common in the mate- 

 rial from Albatross station D4327, off San Diego, Cal., 263-330 

 fathoms. 



Type-specimen.— Oat. No. S259, U.S.N.M. 



This species is perhaps nearest to Critlrionina rugosa and C. ma- 

 milla Goes. It is very much larger than either of those species and 





64 



Figs. 04-05.— Crithionina rotundata. 04, portion of central chamber wall. X 25. 05, view of 



SECTIONAL SPECIMEN SHOWING THICK WALL AND RADIAL TUBES. X 10. 



has a more definite structure. C. mamilla is an attached form of 

 small size. C. rugosa is also a small, subspherical species. I have 

 examined the original specimens of C. rugosa selected by Goes from 

 the type station, and they are all small and largely made up of white, 

 finely granular material of an entirely different appearance from 

 this species. This is by far the largest species yet known in this 

 genus. 



Genus THURAMMINA H. B. Brady, 1879. 



Thurammina H. B. Brady (type, T. papillate II. B. Brady), Quart. Journ. 

 Micr. Sci., vol. 19, 1879, p. 45. — Butschli, in Bronns Klassen unci Ordnungen 

 ties Thierreichs, vol. 1, 1880, p. 202.— II. B. Brady, Rep. Voy. Challenger, 

 Zoology, vol. 9, 1884, p. 321. 



Thyrammina Rhumbler, Arch. Protistk., vol. 3, 1903, p. 23G. 



Lituola \Y. B. Carpenter (part), The Microscope, 5th ed., 1875, p. 533. 



Description. — Test typically free, usually nearly spherical, but in 

 some species compressed, chamber single and undivided in typical 



