lOKAMINIFEEA OF THE ATLANTIC OCEAX. 41 



wall comparatively thin, composed of a felted mass of line amorphous 

 material and a large peirentage of acerose sponge spicules with little 

 or no cement; aperture not developed, sui-face smooth, color grayish 

 white. 



Length, up to 8 mm. 



Distribution. — The type-specimen (No. 10002, U.S.N.M.) is from 

 Albatross station 1)2084, south of Georges Bank, in 1,290 fathoms 

 (40° 16' 50" N.; 67° 05' 15" W.), bottom temperature 40° F. Other 

 specimens were obtained at this station (No. 9892. U.S.N.M.) and 

 at D2571 in 1,356 fathoms in the same general region. 



This species in some ways resembles CritMonina pisum but is 

 elongate, compressed, and has a thinner test. 



r.enus IRIDIA Heron-Allen and Earland. 1914. 



Ii-idia Heron-Allen and Earlani> (type, Iridia diaphana Heron-Alleu and 

 Earland), Trans. Zool. Soc. London, vol. 20, pt. 12, 1914, p. 371. 



Descnption . -Test usually attached, consisting of a single chamber 

 lined with a chitinous, transparent membrane, the outer smrface 

 consisting of sand gi'ains or other foreign material built up in a dome- 

 shaped test, more or less hemispherical, aperture usually wanting. 



The following species is described by the autliors: 



lUIDIA DIAPHANA Heron-Allen and Karlanti. 



Tkurammina papillata (?) Earland, .Tourn. Quel^ett Micr. ( lul), ser. 2, aoI. 9, 



1905, p. 201, 1)1. 11, figs, (i, 7: pi. II, figg. l-o. H F.KON-.Vi.LKX and Earland, 



Joiirn. Roy. Micr. Soc, 1909, p. 323. 

 Wehbina hemisphaerica (?) Hekon-Allen and Eari-and, .louni. Roy. Micr. Soc, 



1909, p. 325, pi. 15, fig. 1^. 

 Iridia diaplimia Heron-Allen and E.a.rland, Trans. Zoo). Soc. London, vol. 20, 



1914, p. 371, pi. 3f), p. 007; Tran.". Linn. Soc T^ond.m. v,)l. IL 1916, p. 218; 



.Tourn. Roy. Micr. Soc, 191fi, p. 37. 



gj The original description of this species is as follows: 



Test adventitious, usually attached, but occasionally more or lees free, consisting 

 of a single ca\ity lined with a chitinous and diaplianous membrane or pellicle. 

 The animal commences its existence as a small hemispherical dome-shaped chamber, 

 white or light gray in color, attached to sand grains or shell fragments, and con- 

 structed of very fine particles of mud and sand cemented together in a rather friable 

 test with a chitinous lining. This chitinous lining is usually continued as a "floor" 

 to the dome-shaped chamber, but in the youngest stage the chitinous "floor" is 

 perhaps not always present. This early dome stage is sometimes furnished with an 

 aperture at the side or top of the dome, but quite as often no special aperture is 

 viflible. The test increases in size l)y the protrusion of the protoplasm in irregular 

 masses, which proceed to secrete a covering investment of sand grains of varying 

 sizes, attached to tlie chitinous lining. The construction of the test becomes coarser 

 with the growth of the organism, and the color becomes darker. With each increase 

 in the size of the test, the inclosing wall of the preceding stage is absorbed so as to 

 leave an undivided cavity, the shape of which varies according to the direction and 

 manner in which additions to the original chamber have been made. In rare instances 



20173—18—4 



