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Bulletin 35 



168 



Page 40 



4. — Climate of the period of deposition. 



Bearing in mind what has been said respecting the 

 proportion of recent and extinct species, it will appear 

 that these deposits probably belong to an epoch not 

 far removed from that of the glacial and preglacial 

 beds of Europe. 



But the extremely small size of the fossils found at 

 Matura is one of the most remarkable features of the 

 deposit. Even where the shells belong to recent types 

 of average size, the fossil representatives are almost 

 invariably dwarfed. There are only one or two excep- 

 tions to this rule, e. g. Cardium isocardium, Turritella 

 imbricata and Bulla striata, which attain an ordinary 

 but not a large growth . 



When the fossils belong to recent types of small 

 size and arctic genera, the}' are not smaller than their 

 living representatives. As examples of this, I may cite 

 Astarte (Gouldia) martinicensis, the Corbulce, the Leda, 

 and the NjicuIcb. 



I have been led from a consideration of the above 

 facts to enquire whether the refrigeration caused by the 

 extension of glacial action southwards during the newer 

 Pliocene period may not have affected lands situated so 

 far south and so near the equator as Trinidad. And 

 it must be confessed, considering the general aspect of 

 the organic remains from the Matura beds, their small 

 size, and the probable contemporaneity of the period of 

 their deposition with the glacial epoch in Europe and 

 North America, that there is some likelihood that gla- 

 cial influences had a share in the modification of the 

 fauna of the Matura beds. The influence of climate 

 seems to show itself in the numerical preponderance of 

 individuals belonging to species of arctic or northern 

 types, and in the diminutive size generally of the shells 

 rather than in the presence of arctic species. 



5. — Relations with other Deposits. 



Several of the species found in the Matura beds are 

 identical with those occurring in the Tamana series, 



