454 ME. H. SANDON ON PEOTOZOA FEOM THE 
found that tests from north polar regions were on ths whole lai'ger than the 
averaoe. 
The present investigation throws little light on this question. Several 
species (e. g. Arcella arenana, Tr.inema complanatuni) included some 
exceptionally big specimens, but others were on the average rather below 
the normal size {Centropyxis aculeata, C. Icevigata, Nebela collaris). Obser- 
vations of this kind are, however, very inconclusive unless based on statistical 
data ; and as no Such data from temperate regions are available for com- 
parison, there was no point in devoting time to obtaining them from the 
present material. It seems, however, fairly certain that there is 'no general 
tendency to either a larger or a smaller size in the Spitsbergen rhizopods, 
and that none of the species found formed an}' distinctive local varieties. 
(2) Species recorded. 
The rhizopods commonly found living on mosses have been divided by 
Penard (24) into two groups which he calls respectively " formes banales " 
{i. e. forms commonly found in mosses but not especially adapted to such 
a life) and " formes caracteristiques " (i. e. forms specially adapted to 
living among mosses and rarely found elsewhere). The former group 
contiiins 26 species, of which 21 have now been recorded from Spitsbergen ; 
but of the second group, only 2 out of- 17 liave so far been found there, and 
one of these is Amceba terricola, which seems out of place in this classifica- 
tion, since, so far from being specially adapted to living among mosses, it 
occurs frequently, as its name implies, in soil. The absence of the " formes 
caracteristiques " is probabl}' due in part to the fact that they include 
a number of naked amcebse which do not normally form cysts, and which 
therefore may have been present in the moss when it was collectedj but died 
before the samples were examined. 
Levander (18) and Heinis (16) have already drawn attention to the close 
similarity existing between the rhizopod fauna of the high latitudes and 
that of the high altitudes of the European Alps, as recorded by Zschokke 
(37), Daday (13), and Heinis (16). The present investigation completely 
confirms this analogy, but unfortunately the data available do not appear to 
be sufficiently complete to extend it to other groups of protozoa. The 
generalisation that Heinis makes with respect to the high Alpine protozoa, 
however, seems to apply equally to the Spitsbergen records : namely, that 
the severity of the climate does not result in the occurrence of local species, 
but simply eliminates tlie less adaptable forms, with the result that the 
population is composed of the most cosmopolitan forms. The possibility of 
the existence of true arctic species is, however, not entirely ruled out by these 
considerations (except in the testaceous forms), since such species, if they 
exist, may hnve died out com;)letely before the material could be examined. 
