522 History of British Entomostraca. 



structure apparently, and of a light colour. Straus says that as lie 

 could not see exactly its termination, he is ignorant of its use, but 

 he supposes that it must be either the salivary glands, or the tes- 

 ticles. The heart and nervous system have as yet escaped obser- 

 vation. 



Habits, Manners, Sfc. — The insects of this genus are inhabitants 

 solely of the fresh water, and are to be found in almost every pond 

 and ditch where the water remains stagnant, but not putrid. They 

 are not so prolific as the Cyclopes, but in some of the larger species 

 we can count, according to Jurine, as many as 24 eggs. The males 

 have never yet been discovered ; and the act of copulation has never 

 been witnessed by any author, with the exception of Ledermuller, 

 who says he has seen them in the act, and gives a representation of 

 them in that state. I have frequently witnessed two individuals in 

 much the same situation as those figured by Ledermuller ; but it 

 did not appear to me that at the time they were engaged in copu- 

 lation ; and as neither Muller, De Geer, Jurine, nor Straus, have 

 ever witnessed them in the act, Ledermuller must in all probability 

 have mistaken the nature of their junction. Straus says, that every 

 specimen he has examined has been laden with eggs, which makes 

 him ask — " Are they hermaphrodites ? or do the males only appear 

 at some particular season of the year ?" Jurine has collected eggs 

 immediately after they had been deposited by the parent insect ; 

 has isolated them, and seen them safely hatched. He has then 

 isolated the young ones after they were hatched, and found that 

 they became pregnant without intervention of males. They must 

 either, therefore, be hermaphrodites, or, as in some other genera, 

 as the Daphnice for instance, one copulation suffices not only to im- 

 pregnate the female for life, but the succeeding generations also. 

 As the males of the Daphnice appear only at particular seasons of 

 the year, and in small numbers, it is probable that the males of the 

 Cypris will be found also by succeeding observers. The eggs are 

 perfectly spherical, (Plate XVI. Fig. 11,) and are deposited by the 

 insect upon some solid body, such as part of some plant, &c, in a 

 mass, sometimes, says Straus, uniting some hundreds from different 

 individuals ; the mother fixing them to the surface of the body on 

 which they are deposited, by means of some glutinous substance, and 

 then leaving them. When the animal is about to lay, it fixes itself, says 

 Jurine, so firmly in some secure place, that it cannot be displaced by 

 any agitation of the water, and is occupied about twelve hours in the 

 operation. The eggs remain about four days and a-half before they are 

 hatched, and then the young at once assume the appearance of the 



