Microscopical Essays. 



555 



It differs from the preceding in feveral refpects, being larger, 

 the body thicker, more cylindrical, and the lower part truncated, 

 with two fhort diverging points projecting from the middle. Was 

 found in a ditch where there was plenty of duck-weed. 



2 36. Cercaria Lupus. Fig. 39, Plate XXV, 



' Cercaria cylindrica, clongata, torofa cauda fpinis duabus. 

 Cylindric cercaria, long, the tail furniihed with two fpines. 



This animalculum is larger than mo ft of the cercarias, and has 

 feme particulars in which it refembles the vorticella. It is full of 

 mufcles, capable of being contracted or extended; cylindric, 

 compofed of a head, a trunk, and a tail ; the head is larger than 

 the body, the apex turned downwards into a little hook ; the 

 tail is like the body, but narrower, terminating in two very bright 

 fpines, that it extends differently. It fometimes contracts itfelf 

 into one half it's fize ; then again it extends itfelf to it's ufual 

 form, Was found in water among duck-weed, a the head, 

 b the trunk, c the tail, dd the fpine thereof. 



137. Cercaria Vermicularis. Fig. 40, 



Cercaria cylindrica annulata/ probofcide exfertili, cauda fpina 

 duplici. Cylindrical, annulated, with a projecting probofcis, two 

 fmal'l fpines for the tail. 



It is a long, cylindrical, flefhy, mutable animalculum, divided 

 into eight or nine rings, or folding plaits, the apex either obtufe 

 or notched into two points, the hind-part rather acute, and ter- 



3X2 mmating 



