CHIROCEPHALUS. 49 



also says that they are incapable of bearing any degree of 

 cold. Jurine, however, found no difficulty in hatching 

 the ova of the Chirocephalus sent to him by Prevost, and 

 keeping the animals so hatched till they reached maturity ; 

 and Shaw distinctly asserts that he has found them in 

 this country in shallow pools, in the months of December 

 and January, even after pretty sharp frosts, as lively 

 almost as in spring or summer. I have always found 

 them in the months of October, November, and December, 

 and even after frosts of short continuance, though of con- 

 siderable severity. In general they have been very short- 

 lived after being removed from their native habitat, but I 

 have been able to hatch the young and watch their 

 progress to maturity. Though they do not appear de- 

 structive to other animals, they fall an easy prey them- 

 selves to various enemies. Frogs, salamanders, the larvEe 

 of the Dytisci, the Cyprides, and other such inhabitants 

 of the water, kill them in vast numbers, and they seem, 

 besides, according to Prevost, to be specially infested by 

 a species ofVorticella, or wheel animalcule, which attaches 

 itself to the body of the animal in great numbers, and 

 would very soon, were it not for their moulting frequently, 

 completely destroy it. I have found them very liable to a 

 peculiar disease, which seems very frequently to terminate 

 fatally. It attacks their body near the external ovary, the 

 lower part of the abdomen, &c., and the branchial feet 

 are not exempt from it. It consists of a white growth, 

 composed of a fatty sort of substance, and when once 

 this appears, the poor animal almost always soon after dies. 

 When copulation takes place, the male glides under- 

 neath the female, and seizing her firmly with his 

 powerful prehensile antennae, forces her to bend her 

 tail towards his abdomen, where the male organs lie. 

 The ova appear at first as small, white, spherical bodies 

 lying in the internal ovary, which stretches along the 

 abdomen, and then passing from it into the external 

 ovary already described. When the proper time arrives, 

 the mother deposits these ova loose in the water, the 



4 



