Fresh -water Entornostraca of South America. 53 



found to occur in the place from which the aquatic plants 

 used for the aquaria were taken, and I did not succeed in 

 detecting any specimens in the alcoholic samples sent from 

 Dr. v. Ihering, there may be a slight possibility that this 

 form, in spite of the precautions taken, has been accidentally 

 transferred to the aquarium. This species is therefore not 

 figured in the accompanying plate, and its name is placed 

 within brackets in the text. 



22. Alona intermedia, G. O. Sars. 



(PI. IX, figs. 4, 4 a). 

 Alona intermedia, G. 0. Sars, 1. c. p. 38. 



Remarks. — This species, established by the present 

 author as early as the year 1862, is easily recognizable from 

 any of the other species of the present genus by the pecu- 

 liar form of the caudal part (see fig. 4 a), which is gra- 

 dually expanded distally, and, moreover, unlike what is gen- 

 erally the case, has the denticles of the lateral rows much 

 stronger than those of the marginal rows. I can see no 

 difference between the Brazilian form figured in the accom- 

 panying plate, and Norwegian specimens. 



Occurrence. — This form occurred not infrequently 

 in some of my aquaria prepared with mud from Sâo Paulo, 

 and some few specimens Avere also found in a sample taken 

 by Dr. v. Ihering at the same place, proving it to be derived 

 in reality from the mud. 



Distribution. — This form has hitherto only been 

 found with certainty in Norway, Sweden and Finland; 

 for the indication of its occurrence in other countries by 

 some authors is regarded by Prof. Lilljeborg as very ques- 

 tionable, since it has generally been confounded with other 



