19s AXXALS XEW YOBE ACADEMY OF SCIEXCE8 



reduce the proportion of strictly South American genera in that division 

 makes us somewhat dubious of there being any marked difference between 

 the two divisions of the Antilles with respect to this relationship. 



As far as the affinity' between the Greater Antilles and Central America 

 (including Mexico) goes, we note that only 2.6 per cent, of the Greater 

 Antillean genera are confined, in their American mainland distribution, 

 to that region. Including all the genera, T3.5 per cent, of those known 

 from the Greater Antilles are known also from Central America and 

 Z\Iexico, but the same percentage for the Lesser Antilles -is 60.2, which is 

 practically the same, in view of the fact that it is so largely based on 

 the St. Vincent fauna. 



As was pointed out several paragraphs before. Cuba has a number of 

 genera known on the American mainland only from United States and 

 Canada, but such genera represent only 5.1 ];ier cent, of the genera known 

 from the Greater Antilles (as a matter of fact, only 7.4 per cent, of the 

 Cuban genera), while the same percentage for the Lesser Antilles is 2.8. 

 Of the Greater Antillean genera 6T.5 per cent, are known also in United 

 States and Canada and 50.9 per cent, of those reported from tbe lesser 

 Antilles. 



This, it seems to me. confirms the notion that. Avliile individual genera 

 differ, the general make-up of the spider fauna of the Lesser Antilles 

 does not significantly differ from that of the Greater Antilles and that 

 neither division has drawn from, or given to. any particular portion of 

 the mainland much more than the other division. 



A comparison of the Porto Eican spiders with those of the other 

 islands brings out some interesting points. It has. as far as we know, 

 no peculiar genera and only ^.8 per cent, of its genera are not known 

 from the other. Antilles. The data for the Lesser Antilles show 6.5 per 

 cent, of peculiar genera and 50 per cent, which are not known from the 

 other Antilles: for Hispaniola the figures are 3.8 per cent, and IT. 3 per 

 cent.: for Cuba. 1.2 per cent, and 29.3 per cent.: and for Jamaica. 6.6 

 per cent, and 20 per cent. The fauna of Porto Eico seems, then, to be 

 of more recent origin than that of the other islands. This idea is 

 strenofthened bv the fact that, while the differences are not 2:reat. onlv 

 30 per cent, of Porto Eican genera are strictly American as compared 

 with 43.5 per cent, for the Lesser Antilles. 4T.1 per cent, for Hispaniola, 

 38.3 per cent, for Cuba and 43.3 per cent, for Jamaica : also by the fol- 

 lowing, which is not strictly a restatement of the preceding, since a genus 

 may be found in the Old World without being so widely distributed as 

 to be classed as cosmopolitan. Cosmopolitan or cosDiotropical genera 

 make up 44.0 per cent, of tbe Porto Eican genera as compared with 20 



