123 



THE PLANKTON FORMS. 



PHYTOPLANKTON. 



The phytoplanktoii was made up of three forms, Ciathrocystis, Coe- 

 losphaerium and Oscinaria. Chithrocystis was much more abundant than 

 the other two forms as it made up about 75 per cent, of the total quan- 

 tity of phytoplanlcton. 



CRUSTACEA. 



Cope pod (I. —My thanlvs are due Prof. C. Dwight Marsh for his deter- 

 mination of the following- copepods: 



EpiscJiiim hiciistris Forbes. 



Diaptoiiuis orvgoncnsis Lillj. 



Diapfoiniis hirgci Marsh. 



Cyclops pidchelliis Koch. 



Cyclops hrevispinosKS Herrick. 



CycJops leiickarti Sars. 



Cyclops alMdus Jurine. 



Cyclops prasiinis Fischer. 



Cyclops sernilatiis Fischer. 



Ergasiliis. 

 The following concerning Diaptomus birgei is quoted from Professor 

 Marsh's letter: '"The finding of D. birgei is of great interest to me. I 

 described the species some years ago from a few specimens from New 

 Lisbon, Wisconsin, and have never seen a specimen since. I had begun 

 to fear tliat I had described a freak form and that the species would not 

 stand; )>ut here comes the creature in the proper proportions. It is a 

 little (pieer that I should have found it only in two such widely separated 

 localities, but doulitless it lives at some intermediate locations." 

 Clad or era. —The following linmetic forms were found: 



Daphnia hyalhia Leyd. 



Daphnia pulene De G. var. pulicaria Forbes. 



Daphnia retrocurva Forbes. 



DiapJiaiiosonia Jtydchynntm Sars. 



Ccriodaphnia laciistris Birge. 



Lcptodora hynlina Lillj. 



Clii/donis. 



Bos mi)} (I. 



