52 G. O. Sars. 



with the caudal part more highly magnified. The A. Com- 

 bouei of Bichard is very nearly related to the present species; 

 but in his figures, besides the marginal denticles of the tail, 

 a lateral row of delicate denticles is indicated, not found in 

 any of the specimens examined by me. The Australian form, 

 A. clathrata G. O. Sars, also appears to be closely allied 

 to the species under consideration. 



Occurrence. — Numerous specimens of this small 

 Lynceid developed in some of my aquaria prepared with 

 mud from Sâo Paulo. That the specimens were in fact de- 

 rived from the ,nrad, and not accidentally transferred, is 

 proved by the occurrence of a few specimens in an alcoholic 

 sample from the same place, kindly sent to me by Dr. v. 

 Ihering. Moreover, the same species has also recently been 

 recorded by Dr. Vavra from other regions of South Ame- 

 rica, viz., from Chili, the Falkland islands, and Tierra del 

 Fuego. 



Distribution. — In Europe, this form seems to be 

 very generally distributed, and it has, moreover, been recorded 

 from the Caucasus, Syria, Algiers, the Azores, and North 

 America. 



(21. Alona rectangula, G. O Sars.) 

 Alona rectangula, G. 0. Sars, 1. c, p. 18. 



Remarks. — I am not quite assured that the several 

 forms referred by Prof. Lilljeborg to this species are in 

 reality identical. The specimens which I have met with 

 here in Norway, are all of a very uniform appearance, both 

 as to size, form, sculpturing of the shell, and other characters. 



Some few specimens found in one of my aquaria exactly 

 agreed with the Norwegian form; but as this species was 



