168 J). J. SCOUHFIELD ON ENTOMO.STRACA. 



consequence of the great rarity of these forms in many species. 

 Altogether I have seen sixteen males and eighteen ephippial 

 females. They are given at length, and their seasonal distribu- 

 tion is shown in the third table appended to this paper (see 

 also lower curve of diagram). I do not think any of them are 

 new, with the possible exception of Alona costata, but there is 

 no reason why many successes should not reward diligent search 

 in this direction, as the males and ephippial females of a great 

 many species still remain to be discovered. And here I may 

 remark that much of the uncertainty as to the value of some 

 genera in this order seems to me to arise from the fact that 

 the original descriptions were necessarily based entirely upon 

 the parthenogenetic females. In any future revision of the 

 classification of these animals, the males and sexually mature 

 females will certainly have to be taken largely into account. 



The results obtained in reference to the seasonal distribution 

 of the Ostracoda and Copepoda are somewhat vague, and not 

 very suggestive, but a short space may be conveniently devoted 

 to them among these more or less indefinite items that we are 

 now considering. It seems that the animals included in these 

 orders, as might, perhaps, have been anticipated, are pretty 

 evenly distributed through the whole year. If they do possess 

 a culminating period it is very probably not the same as that 

 of the Cladocera. It would rather seem as if the maximum 

 development of species was reached in the early part of the 

 year — by the Ostracoda in February and March, and by the 

 Copepoda in April. This is shown by the following statement 

 of the average number of species belonging to the two orders 

 found during the three years : — 



Jan. Feb. Mch, Apl. May Juue July Aug. Sep. Oct. Nov, Dec. 

 Ostracoda .. 6876 4 4535544 

 Copepoda ... 9 9 9 11 8 10 7 7 8 7 8 9 



It is quite clear, however, that a large amount of very care- 

 ful research is still needed to get trustworthy conclusions upon 

 this subject. 



The last of these miscellaneous points that seems to call for 

 notice is in connection with the distribution of species within 

 the Park itself. By keeping separate records for the various 

 ponds, I hoped at one time to get some evidence of well-marked 

 sub-areas, characterized by special forms, and also, perhaps, 



