50 NATURAL HISTORY 



it at figure 23. It is very restless, continually chang- 

 ing its position. Found in water that has been kept 

 for some time and become foetid. 



39. Enchelis punctifera. The dotted Enchelis, — This 

 species is of an opaque green, like the last, but has its 

 posterior terminated acutely, and the anterior or head 

 rounded obtusely. A small pellucid spot may be ob- 

 served in the latter, and sometimes two black points. 

 When it is about to propagate, which it does by a trans- 

 verse division of the body, the centre becomes more 

 transparent, giving the appearance of a band around 

 the middle of the body. The mouth, as usual, is marked 

 by a cross. A drawing of it, magnified, is given at figure 

 24. I conceive it probable that further observations may 

 find it to be only a variety of the Cercaria viridis. Found 

 in marshes, 



40. Enchelis ovulum. The egg-shaped Enchelis. — This 

 animalcule is distinguished by its pellucid appearance 

 and the longitudinal folds of the external membrane. 

 A few bright spots are also sometimes observed ; these 

 have been supposed to be the ova, but it is more pro- 

 bable they are the sacs of the polygastric structure. 

 Figure 24' is a magnified representation, shewing the 

 sacs and folds, neither of which are constant. Found in 

 stagnant water, 



41. Eisi CHE1.1S fritillis. The dice-box Enchelis. — In ac- 

 cordance with MuUer's arrangement, I have given this 

 animalcule, though there is no doubt it is a species of 

 the Vorticella before the footstalk has grown, (see For- 



