Heuon-Ali.en A^D Eari and — Shidy of Vcrneuilwa poJystro'pha. 167 



names which, as Parker and Junes observed so early as 18G0, " keeps up a 

 false notion of the value of external characters which are rarely essential, 

 whilst no clue is thereby obtained to the morphological law of eacli real 

 specific type."'" 



The second was the observation of the fact that certain arenaceous 

 Foraminifera exhibit a tendency to select and incorporate heavy minerals 

 and gems in their tests. Thus Haplophragmium agglutinatus, d'Orb., builds 

 magnetite grains into its test whenever that mineral occurs in its surround- 

 ings." We have recorded the same affinity for magnetite iu specimens of 

 lieophax dijfiugiforinis, Brady, from the West Coast of New Zealand," and 

 have recently found Jaadella acuta, Brady, from New Zealand ('' Terra Nova " 

 Station 96, TO fms.), incorporating magnetite and other heavy minerals 

 largely in the outer layer of its massive tests, while constructing the whole 

 of the interior test of white quartz grains. Verneuilina folystroflia (Reuss) 

 betrays a similar tendency to select and incorporate in its test minerals of 

 all kinds, and, regard being had to the much higher specific gravity of these 

 minerals as compared with that of ordinary siliceous sand-grains, the habit 

 becomes highly significant. The phenomenon was fii'st forced upon our 

 notice in the case of a number of specimens gathered from the Mixon 

 Eeef at Selsey in 1907, described by us in 1909,*° and at greater length by 

 Heron-Allen in 1915," and the experiments described below were then set 

 on foot. 



The "history" of the species Vernnnliiui 'polydro^pha is in itself 

 interesting as recording the stages in the evolution and diagnosis of a species, 

 and we may introduce the subject with a brief summary of that history. 



The species was first described by Eeuss in 1846 as Bulimina 2}oh/st roplia, 



■•- T. Rupert Jones and W. K. Parker : " On the Rhizopodal Fauna of the 

 Mediterranean." Q. J. Geol. Soc, vol. xvi, 1S60, pp. 293-294. (See also T. R. Jone.s : 

 " Remarks on the Foraminifera." Monthly Micr. Jour., 1876, p. 72.) The too little 

 remembered observations of W. B. Carpenter upon systematists who described 

 " specimens " instead of "species," require no excuse for quotation. '-Everyone who 

 makes a bad species is really doing a serious detriment to science ; whilst ever3'one who 

 proves the identity of species previously accounted distinct is contributing towards its 

 simplification, and is therefore one of its truest benefactors." (Royal lust., Gt. Britain, 

 1858, Mar. 12, Reprint, p. 6.) In this connexion we may refer to our recently 

 published paper on Tliitrammiiia papillata, Brady. A Study in Variation. (J. R. Micr. 

 Soc, 1918, pp. 530-557, Pis. xxvi-xxx.): in which we established tlie morphological 

 identity of all the previously recorded " species" of Thurammina. 



^^ Described and figured by us in "Knowledge." Loc. cit (note 2t)), p. 421, fig. 1. 



■** Luc. cit. (note 23), p. 2G7, PI. xviii, fig. 64. 



■1^ Loc. cit. (note 40), 1909, p .327, and E. Heron-Allen. J. R. Micr. Soc. 191.% 

 pp. 548-549. 



«ioc. cit. (note 23), p. 2()7. 



