1887.] 



ON CYCLESTHERIA HISLOPI. 



V. 



Biological Observations. 



The first specimen of the present Phyllopod observed by 

 the author, was quite a young individual, which, by mere chance. 

 had been drawn up in the dipping-tube. on the 29th June. when I 

 was examining one of my aquaries, prepared on the 14th of that 

 month. Xotwithstanding the most careful examination by the 

 aid of a hand-magnifier, I could not detect at the time any 

 other specimens in the aquary, nor the slightest trace of larval 

 forms. On the Ist July the same specimen was fished up for 

 closer examination. Its shell at that time only slightly exceeded 

 2 mm. in length and had two distinctly marked lines of 

 growth. A figure of this specimen, drawn from life. is given 

 Pl. VIII, fig. 4. No other specimens were detected during the 

 four succeediug days. either in this or in any other of my aquaries, 

 .md I feared therefore that my investigation of this interesting 

 form would be restricted to the sole specimen already examined. 

 But on the 7th July, when examining the same aquary, by the 

 aid of a hand-lens. in search for other Entomostraca, I w 7 as most 

 agreeably surprised on discovering a full-grown specimen of this 

 Phyllopod swimming actively about among the numerous Confervæ 

 growing in the aquary. This specimen. moreover. exhibited at 

 first sight a most interesting and quite unexpected character, in 

 liaviug the upper part of its shell filled up with numerous fully 



