182 



NATURAL HISTORY 



uniform. The posterior is concave, and the tail forked- 

 Found with the Vorticella rotatoria. 



The two following animalcules have been discovered 

 since Miiller's time, but cannot be admitted into any of 

 his genera : it may be advisable, therefore, to describe 

 them here, though it is probable they do not strictly 

 belong to this class of animated beings ; yet, as their 

 structure is very peculiar, and they are but little known, 

 a short account of them may be interesting : they are 

 figured in Vol. II. of Brewster's Encyclopedia. 



434. The Urslet is a translucent creature, about the 

 size of the wheel animalcule (396.) When viewed side- 

 ways, its contour resembles that of the Polar Bear ; it has 

 four pair of feet, the last pair occupying the situation of 

 a tail, and all of them are furnished with three sharp 

 claws : it sheds its skin, which is smooth, although the 

 body is wrinkled ; a cluster of ova may be observed near 

 the back, which is convex. These were discovered in 

 Germany, and subsequently found in Scotland ; but were 

 unknown in England until lately, when Samuel Powell, 

 Esq. found some specimens at the bottom of some clear 

 water, containing lemna and confervas, obtained from a 

 pond on the Portland Town side of the Regent's Park : 

 a few of these he kindly sent me : they appeared very 

 sluggish and unw^ieldy, and did not swim, but remained at 



