32 Ct. 0. Sårs. 



Biological Observations. 



Several specimens of this pretty form, males and females, 

 also developed in my aquaria, and were kept alive until 

 late in the summer. When fully grown, they were readily 

 distinguished from the other Branchipodid described above 

 by their less slender form, but especially by the different 

 shape of the marsupium in the female, and of the prehensile 

 antennæ in the male. The latter, moreover, was easily 

 recognized by the enormous development of the caudal rami. 

 For a closer examination, the specimens were transferred 

 to separate aquaria not containing specimens of the other 

 Branchipodid. In habits the two forms agree, in as much 

 as they are never found at the bottom, like the species of 

 Apus and Estheria, but always freely suspended in the 

 water. The manner in which the swimming movements are 

 effected, is likewise the same in both forms, and also the 

 attitude of the body. But the degree of agility in the 

 present form is rather different according to the sexes. In 

 the ovigerous female the motions seemed to be very much 

 encumbered by the heaviness of the large marsupium, and 

 she was often found for a long time occupying nearly the 

 same place in the aquarium, only slowly turning round on 

 her axis, though the branchial legs were seen to be in rapid 

 swinging motion. The male, on the other hand, scarcely 

 stopped for a moment, but swam about with great agility 

 in all directions, and it was very difficult indeed to catch 

 it by the ordinary means. 



In this form I was equally unsuccessful in witnessing 

 the copulative act, though the specimens were watched nearly 

 every day. The female deposited her eggs at short intervals, 

 and, unlike what was the case with Streptocephalus gracilis, 



