GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 1525 



but giving to the Temperate zone almost all the species of the group.* 

 Moreover, no Daphnioids and few Caligoids have been yet reported 

 from the Torrid zone, excepting those described in this Report. The 

 author's time when on land in the tropics was devoted mainly to the 

 department of Geology, and consequently the fresh-water Entomostra- 

 cans were not as thoroughly collected as those of the oceans. He 

 therefore attempts to draw no conclusions from the above ratios. 



A few facts may, however, be deduced with respect to some genera, 

 and especially those of the Cyclopoidea. The following table gives 

 the number, as nearly as known, of the species of each genus of the 

 Cyclopoidea, occurring in the torrid and extra-torrid zones. The 

 number" common to the extra-torrid and torrid zones is mentioned in 

 brackets. 



TABLE V. 

 CYCLOPOIDEA. 



* The whole number of Cyclopoidea described previous to May, 1842, by which time 

 the author's observations were completed, was less than twenty-Jive; and of the oceanic 

 Cyclopoids, one hundred and fifty species of which the author has described, not ten were 

 then known. We may judge from these results of a single cruise, what still remains to 

 be done in the department of Entomostraca. 



382 



