18 Transactions of the Society. 



St. Kilda in 1600 metres, the sea-bottom being Glohigerina ooze 

 Here the spiculiferous variety parva is of quite frequent occurrence. 

 In view of such facts, and of the added fact that two other species 

 of Psammosph^ra, which we have described from ' Goldseeker ' 

 dredgings 0.3), display marked selective powers, we cannot but 

 arrive at the conclusions that the presence of this central spindle 

 in var. parva is not fortuitous, but that the animal deliberately 

 chooses the spicule as a main constituent of its ''house," and con- 

 structs its abode round the spicule in order to obtain the increased 

 support afforded by its projections in supporting itself upon the 

 surface layers of the bottom ooze. 



Psammosphsera fusca var. testacea is of an entirely different 

 habit. It cannot in any way be regarded as a selective organism, 

 but rather as a Psamiaosphsera which utilizes the tests of other 

 Foraminifera in the construction of its " house " merely because 

 they chance to be the material most ready to hand (Plate II, 

 fig. 9). 



But on the other hand, we cannot but consider that the occur- 

 rence of this variety of PsamiiiOsp)h8ira, building its tests entirely of 

 the shells of other Foi-aminifera in the same dredgimj as Saccam- 

 mina sphasrica, building its test entirely of sand-grains, is fatal to 

 Dr. Ehumbler's theory of the identity {Vereinigung) of the two 

 species. Although it is of quite common occurrence to find a 

 Saccammina with the tests of one or two Foraminifera (usually of 

 large species) projecting from the shell-wall, into which they have 

 been built, we have never seen a specimen entirely or even mainly 

 constructed out of the shells of other and smaller species, even in 

 dredgings in which Psammosphsera fuscaYdiV. testacea abounds. 



Therefore, it is not irrelevant to ask : — If, as in accordance 

 with Dr. Ehumbler's theory, Psammosphsera fusca develops into 

 Saccammina sphserica, what becomes of Psammosphwra fusca var. 

 testacea ? 



Analysis of Dredgings Examined. 



P.Lp>lanatorg Notes. 



To facilitate reference to the Chart, the dredgings have been 

 arranged in four groups. There is, of course, no suggestion that 

 these represent definite zoological areas. 



The hauls marked with a letter, X, Y, Z, etc , represent material 

 obtained from the masters of several steam trawlers, through 

 Dr. A. Bowman, D.Sc, of Aberdeen. All the other hauls are from 

 dredgings, etc, made by the ' Goldseeker,' and, except in the few 

 cases noted in the Ilemarks column, the amount of material avail- 

 able and used was large. 



Abbreviations, m = mud ; s -- sand ; sh = shell ; gr. = gravel ; 

 st = stones ; o = ooze ; gl = globigerina ; c = coarse ; f = fine. 



