MARINE ALGAL FLORA 263 



bean. Some 790 species are well-known entities, contrasting with about 

 330 which are ill-supported either taxonomically or geographically and 

 do not enter into our tables. Known synonyms are excluded. Of this 790, 

 less than half, or 317 species, have been found in at least five places 

 (countries or major islands), the discrepancy being greatest among the 

 Rhodophyceae, where there are many small species, with only 1 72 out of 

 the 468 species collected in as many as five places. 



If we consider now how many better known species of the total in 

 each algal class range north or south from the Caribbean, we find the 

 analysis in the first percentage column. Altogether, 43 per cent of the 

 Chlorophyceae are known from five stations or more. Of these, 27 

 species are apparently strictly Caribbean, and this is 12.6 per cent of all 

 the Chlorophyceae known from the region, or 8.5 per cent of all ade- 

 quately reported species. Of the Chlorophyceae, the distribution of 57 

 per cent is not well enough known to make it wise to consider them in 

 the analysis. The other range groups and algal classes can be compared 

 in the same way. This first percentage column shows that all algal groups 

 range less to the north than to the south, but as the data are clouded by 

 the many species about which we know too little, the second table based 

 on commoner species offers a better analysis. The last percentage column 

 is valid and does show what proportion each range group contributes to 

 the total flora of more frequently reported species. Quite as we would 

 expect, the Rhodophyceae contribute most, but of the Rhodophyceae those 

 which range northwards are much fewer (6.6 per cent) than those with 

 southward tendencies (15.1 a« ^ i6;€ per cent respectively). In the 

 Phaeophyceae, the strictly Caribbean species are relatively much fewer 

 (3.1 per cent) than the species with southern tendencies (8.0 and 4.7 

 per cent), and it is curious that so very few (1.0 per cent) have north- 

 ward tendencies. 



TABLE 2 



Chloro- Phaeo- Rhodo- All 



phyceae phyceae phyceae Groups 



Strictly Caribbean 29.3 18.8 30.8 28.4 



Caribbean and Northern 12.0 5.7 12.2 11.0 



Caribbean and Southern 34.8 47.2 27.9 33.1 



Widespread North and South 23.9 28.3 29.1 27.5 



Percentage of each range type in the several algal classes, based on well-known 

 species (317) each reported from 5 or more stations. 



The second table shows the flora of species well known from five or 

 more stations where the percentages relate the number in each range type 



