Heron-Allen and Earland — Studij of Verneuilinupoli/iitropha. 165 



some period of their iife-liistory, or in certain specialized localities, firmly 

 adherent to sand grains, mollnscan fra^mcTits, or other organisms, by means 

 of a distinctive cement formed of quartz grains. The biological significance 

 of this modification is still obscure. It reaches, perhaps, its highest develop- 

 ment in Vahndinn fnsca Will., but it has been noted by many authors." 

 Williamson records Lagenae, found adherent to Fuci and Byssus by 

 MacGilli^'ray, and to Antedon rosacea from Plymouth by Jeffreys," and 

 among the "Euna" dredgings of Professor W. A. Herdman from the West 

 of Scotland wc found a remarkable series of Tcxtularia sagittula, Defr., 

 firmly adherent to algae by their apertures." 



Among the " Terra Nova" material at Antarctic Station 388, Truncatulina 

 refulf/cns (Montf.) occurs abundantly in a sessile form on Bryozoa. This 

 would be a normal habitat, but nearly all the specimens present an abnormal 

 variation in the presence of radiating tubes of sandy material, either attached 

 to the surface of the Bryozoa, or projecting freely from the organism. 



An interesting illustration of the variation due to sessile habit can be 

 found in Pohif reran minictceirin, Pallas." This organism appears to ns to start 

 life in one of two ways, and wliat may determine the plan it adopts is entirely 

 obscure, (a) It usually starts life as an adherent primordial chamber 

 surrounded by a typically rotalian series of chambers, plainly distinguishable 

 when the organism is removed from its liost.^" This is immediately followed 

 by an expanding encrusting base, and the organism then rises into arbores- 

 cent pillars, composed of acervuline masses of irregularly shaped chambers ; 

 (b) but this rotaline base is in many cases invisible when the specimen is 

 detached from its base. In these cases it would appear that the creature 

 has started life as a free and independent organism, consisting of a central 

 chamber surrounded on all sides by smaller ones on an irregular rotaline 

 plau. This was first noted by Schlumberger." This free organism then 

 attaches itself to a base, and proceeds to grow on the familiar arborescent 



•'- See F. Chapman : " On the appearance of some Foraminifera in the living condi- 

 dition from the Challenger Collection." Proc. Roy. Soc. Edinburgh, vol. xxiii, 1901, 

 pp. 391-395, Pis. i and ii. 



-"■^ Loc. cii. (note 1), p. 11. 



^E. Heron- Allen and A. Earland : "The Foraminifera of the We.st of Scotland." 

 Trans. Linn. Soc. (London), Ser. 2. Zoology, vol. xi, 1916, p. 229. Chapman ha.s re- 

 corded and figured similar specimens from the Ki Islands ("Challenger," Stn. 232). 

 Loc. cit. (note 32), p. 392, PI. i. 



■'•' See Lister. Loc. cit. (note 5), p. 123, et seq., fig 51. 



^^ .\r. Schultze : " Ueber Polycrema niiniacenm." Wiegmann's Archiv fur Naturges, 

 Jahrg. 29, vol. i, 1863. p. 81, et seij., PI. viii. (Transl. Ann. Nat. Hist., Ser. 3. vol. xii, 

 1863, p. 409, et seg., PI. vii, fig. 6.) 



■*" C. Sihlumberger : "Note pie'liminairo sur les Fiir.iminilerus draguus, par S A. 

 le Prince Albert de Monaco." Mem. Soc. Zool., France, vol. v, 1892, p. 196, tig. 5. 



