FORAMINIFERA OF THE ATLANTIC OCEAN. 43 



3 mm. in diameter, the cone much depressed and exhibiting a well- 

 marked apical aperture closed in with fine sand grains. The walls of 

 the cone in the Goldseeker specimen are entirely composed of acerate 

 sponge spicules laid regularly side by side as in the type." 



The same authors refer a specimen attached to Zostera from 

 shallow water in the Kerimba Arcliipelago to this species. The ar- 

 rangement of the spicules is very different in their figured specimen, 

 and the materials are differently arranged. This latter may be a 

 new geims and species of shallow-water habitat in tropical regions. 



The following notes are from the original paper of Vaughan Jen- 

 nings : 



The s}}icular structure is in this case the more remarkable since there can be no 

 question as to the abundance of other mateiial at hand. The Botellina shells are con- 

 structed of coarse sand grains, and by far the greater part of the dredging consists of 

 similar material. In fact, the contrast between these delicate spicular cones and the 

 coarse sandy structure of the organism on which they rest is one of the most striking 

 instances I know of the selective power in Protozoa. 



At the base the shell is fixed to the rough surface of the Botellina ])y a small amount 

 of a white, doubtless calcareous, cement; but in the walls there is very little inter- 

 stitial matter. 



In the dry specimen the apex of the coue is closed; l:)ut I should think it probable 

 that in the living condition the spicules were more or less mobile, so as to separate to 

 some extent at the top, and allow a free passage of the protoplasm to the exterior. 



Such a species as this brings to mind at once the question of how it 

 may be formed. If Botellina is a comparatively fixed form, any 

 attached specimen on it would have little opportunity of gathering 

 such complete spicules as the test of RhapMdoscene conica shows in 

 sufficient quantity to produce such a test. May it not be that the 

 individual exists for a time like a plasmodium or other naked proto- 

 plasm capable of free movement, and therefore of ingesting spicules, 

 until it finally settles down and uses these spicules in the construction 

 of a definitely placed, attached test ? This would not be so unhke the 

 process adopted by some of the other Rhizopods in the construction 

 of their test. 



Genus SACCAMMINA Carpenter, 1869. 



Saccammina (type, ^S". sphaerica M. Sars) G. O. Sars, Forh. Selsk. Christiania, 1868 

 ("1869), p. 248 {nonien nudum). — Carpenter, Ann. Mag. Nat. Hist., ser. 4, 

 vol. 4, 18ti9, p. 289. — BIjtschli, in Bronn, Klassen und Ordnungen Thier- 

 reichs, vol. 1, 1880, p. 195. — H. B. Brady, Rep. Voy. Challenger, Zoology, 

 vol. 9, 1884, p. 252. — Rhumbler, Zeitschr. Wiss. Zool., vol. 57, 1894, p. 

 462. — EiMER and Fukert (part), Zeitschr. Wiss. Zool., vol. 65, 1899, p. 671. — 

 Rhumbler, Arch. Prot., vol. 3, 1903, p. 242. — Cusuman, Bull. 71, U. S. Nat. 

 Mus., pt. J, 1910, p. 38.— Rhumbler, Foram. Plankton Exped., Toil 2, 1913, 

 p. 375. 



Description. — Test typically free, sometimes attached, consisting 

 of a single chamber or of several spherical chambers with distinct 

 apertures, usually one for each chamber; wall composed of sand 

 graijis finely cemented by a yellowish or brownisii cement; aperture 

 circular, usually with a short neck. 



