CATALOGUE 



OF 



MADREPORARIA, 



Volume vi. 



The Genus PORITES. 



Part II. 



PORITES OF THE ATLANTIC AND 

 WEST INDIAN AREA. 



I. INTRODUCTORY. 



Volume V. contains a list with descriptions, analytical tables, and illustrations of the forms 

 of this genus — the most ubiquitous of all reef-forming corals — which are known to belong to 

 the Indo-Pacific region. Large as the list is, we may legitimately conclude that it repre- 

 sents but a small selection of the forms now inhabiting that vast area, while the few mentions 

 of fossils supply little more than a hint as to the previous existence of many generations 

 ancestral to those now living round its innumerable shores or building up its reefs. 



This Volume is a continuation of our account of the genus, but contains the forms which 

 are so far known living in the Atlantic Oceans, North and South, in the West Indian 

 Islands and Gulf of Mexico on the west, and fossil in the Paris and Mediterranean Basins on 

 the east. 



The division of the genus into the Indo-Pacific and the Atlantic and West Indian forms 

 each treated in a separate volume is morphologically justifiable, because the latter prove on 

 examination to have characters of their own which constitute them a group apart. This point 

 is especially interesting. It is in keeping with the conclusion at which our work has brought 

 us : that while free-living organisms with highly developed powers of locomotion, such as fish 

 or birds, may spread freely over the surface of the globe, and thus be largely independent of 



