55§ 



Microscopical Essays. 



It is an oval, pellucid membrane, fomething larger than the 

 mona lens. The fore-edge thick and truncated, the hinder-part 

 acute, or terminating in a Ihort tail, It whirls about in various 

 directions with great velocity. 



143. Cercaria Difcus. 



Cercaria orbicularis, cauda curvata. A fmall orbicular cerca- 

 ria, with a bent tail. 



144. Cercaria Orbis. 



Cercaria orbicularis, feta caudali duplici Iongiffima. Orbicular 

 cercaria, with a tail, confining of two very long briftles. 



145. Cercaria Luna. 



Cercaria orbicularis, cauda lineari duplici brevi. Orbicular 

 cercaria, with two fhort fpines for a tail ; the fore-part hollow- 

 ed, fo as to form a kind of crefcent. 



XII, Leucophra. 



Vermis inconfpicuus, pellucidus, undique ciliatus. An invifible 

 worm, pellucid and every where ciliated. 



■ / , 



146. Leu- 



