FJiESH. WA TER CB US TA CEA. 



839 



of a delicate comb on the claws sufficiently identify these specimens with M. 

 dubia. The following table will make the comparison clear :— 



Moina duhia is a characteristic feature of the plankton of the Nile throutrhout 

 its length, and is found in Victoria Nyanza, where it forms the bulk of the 

 plankton (Daday) and in various places in the neighbourhood of Lake Nyassa. 

 It was originally described from West Africa (Senegal) and is evidently a widely 

 distributed African species. On the other hand I have seen specimens hatched 

 from dried mud from Palestine, and its occurrence there is comparable to that 

 of the Nilotic species of fish and other vertebrates. Its extension to the Tigris 

 region is noteworthy, though the Cladocera are not a suitable group from which 

 to draw evidence for zoogeographical problems. 



Bosmina longirostris, O. F. M. 



Ezra's Tomb, Mesopotamia. 



Alona costata, Sars. 



Ezra's Tomb. One individual only. 



Alona guttata, Sars. 



Enzeli, North Persia. Rare. 



Alona rectangula, Sars. 



Ezra's Tomb, Mesopotamia and Enzeli, North Persia. 



Alonella excisa (Fischer). 



Resht and Enzeli, North Persia. 



Pleurozus aduncus (Jurine). 



A single specimen taken at Amara (Bet Khodayer). 



Alonella excisa (Fischer). 



Resht and Enzeli, North Persia. 



Chydorus sphcericus, O. F. M. 



A very strongly reticulate form occurred at Ezra's Tomb. Abundant in a 

 collection from Resht, males and ephippial females being present. 



3. Copepoda. 



Cyclops vicinus, Uljanin. 



Ezra's Tomb, rare. The occurrence of this species in this locality is somewhat 

 surprising, having regard to the extreme heat of the waters of the Amara dis- 

 trict in summer, since it is a distinctly northern species, like its close ally C. 

 strenuus. It has been recorded from Sweden, Central Asia, Turkestan, Kolguev, 

 Volga Delta, Aral Sea and China. My specimens agree in every respect with 

 the description given by Prof. Sars (Crustacea of Norway). 



