THE MARINE FAUNA OF THE FALKLAND ISLANDS. 77 



Schizoporella. The genus is cosmopolitan. The species S. hyalina 

 is cosmopolitan, it occurs on shells, stones, weed, etc., from shallow to 

 deep water, it is fossil, and occurs in coralline crag, Scottish glacial 

 deposits, post-pliocene deposits (Canada). Greatest depth : of species 

 100 fath. (Davis St.), of the genus 300 fath. (off Norway). 



Both the cosmopolitan species Schizoporella hyalina and Microporella 

 ciliata occur fossil, and might be remnants of a once universal fauna. 

 Evidence shows that these forms have been able to withstand all 

 changes of temperature and altered conditions of life, without either 

 becoming extinct or undergoing modification so far as the hard parts 

 are concerned. 



Smittia. The genus appears to be cosmopolitan. It is found among 

 the fossil tertiary deposits. It inhabits shallow and moderately deep 

 water, the greatest recorded depth being 600 fath. (S. smittiana). 



Smittia landsborovii appears to be characteristic of north and south 

 temperate and cold seas, from shallow water to great depths. Fossil : 

 Scottish glacial deposits. 



The species S. trispinosa occurs in temperate and tropical zones, 

 in shallow water and at great depths. 



Porella. The genus is cosmopolitan, and is represented in the 

 tertiary deposits. It occurs in shallow water chiefly, but does also 

 occur at moderate depths. 



These results, as far as the Bryozoa are concerned, seem to support 

 Murray's theory on geographical distribution. 



Each genus represented in the collection occurs fossil, and also occurs 

 in the north and south temperate zones, as well as in the tropics ; in 

 fact, most of the genera are cosmopolitan. 



Many of the species are represented in the tertiary deposits. This 

 shows that the changes of climate and altered conditions of life, have 

 not affected their " tertiary " structure ; as many of these forms occur 

 only in the two temperate zones, there is reason to believe that they 

 have retained their common ancestral structure. 



The fact of many of the species occurring in the deep sea hardly 

 supports Oitmann's theory, for many of them occur at very great depths 

 only in the temperate regions ; in the tropics they occur in shalloiv water. 

 Their presence in the deep sea is, I think, the result of accident. 



