FORAMINIFERA OF THE NORTH PACIFIC OCEAN. 75 



Genus POLYTREMA Risso, 1826. 



Millepora (part) Linnaeus, Syst. Nat., ed. 13 (Gmelin's) vol. 1, 1788, p. 3784. 

 Polytrema Risso (type, P. corallina Risso), Hist. Nat. Europ. Mend., vol. 5, 1826, 



p. 340.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 719. 

 Pustularia Gray, Proc. Zool. Soc. London, vol. 26, 1858, p. 271. 



Description. — Test adherent; early chambers small, spirally 

 arranged, soon covered by the irregular loosely growing chambers 

 making an irregular spreading mass, later chambers forming an 

 arborescent growth; wall calcareous, areolated, numerous apertures 

 appearing at the surface on papillse; interior often of loosely arranged 

 chambers with lacunae between ; color red or pink or sometimes white. 



This genus was for a long time considered as belonging to the old 

 group of "Zoophytes." Its external appearance is sufficient for an 

 understanding of this error but a study of the structure shows it to be a 

 foraminifer. The early chambers with their spiral growth place it 

 with Discorbina and other genera of the Rotaliidse. It is a rather 

 unusual type of the group and is usually found in comparatively 

 shallow water of coral reefs in abundance but ranges out of the 

 tropics both north and south and is found in as great depths as 1,000 

 fathoms, according to the Challenger Report. 



POLYTREMA MINIACEUM (Linnaeus). 

 Plate 18, fig. 6; plate 20, fig. 4. 



Millepora miniacea Linnaeus, Syst. Nat., ed. 13 (Gmelin's), vol. 1, pt. 6, 1788, 

 p. 3784, No. 6. 



Polytrema miniaceum Blainville, Diet. Sci. Nat., vol. 42, 1826, Atlas, Zooph., 

 vol. 1, p. 17; ?Actinologie, 1834, pp. 410, 673, pi. 69, figs. 4, 4a— Car- 

 penter, Parker, and Jones, Introd. Foram., 1862, p. 235, pi. 13, figs. 18- 

 20.— Carter, Ann. Mag. Nat. Hist., ser. 4, vol.17, 1876, p. 185, pi. 13, figs. 

 1-6. — Moebius, Foram. von Mauritius, 1880, p. 85, pi. 7. — H. B. Brady, 

 Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 721, pi. 100, figs. 5-9, pi. 101, 

 fig. 1. — Egger, Abh. kon. bay. Akad. Wiss. Miincben, 01. n, vol. 18, 1893, 

 p. 437, pi. 21, figs. 1, 2, 16, 17. — Sidebottom, Mem. and Proc. Manchester 

 Lit. and Philos. Soc, vol. 54, pt. 3, 1910, p. 29. 



Description. — Test attached, early portion close coiled, consisting 

 of several chambers, later portion consisting of a mass of small 

 chambers arranged in irregular layers, whole more or less arborescent; 

 surface with conspicuous apertural openings; wall areolated; color 

 various shades of red. 



Length up to 5 mm or more. 



Distribution. — This species is apparently not definitely recorded 

 from the North Pacific. The only material I have had was from 

 Albatross station D 4922 in Vincemies or Colnett Strait in 60 fathoms 

 bottom temperature 79.2° F. 



This is typically a species of warm waters, attached to various 

 objects and does not at all resemble the usual forms of Foraminifera. 

 Only its early chambers, which can not be seen except by breaking 

 away the specimen, show the close coiled, several chambered young, 

 which indicate its relationship to the other members of this family. 



