120 DESCRIPTION OF {Polygaatrica. 



others vertically, and then again on their edges, like the 

 rotation of a wheel. A magnifying power of 200 times is 

 sufficient for general examination; but to exhibit all the 

 structures shewn in the engravings, four times that power 

 will be required. Found in clear water, salt and fresh, 

 near the surface. Discovered by Midler, in clear water, 

 at Copenhagen, 1773. Size of animalcule from l-460th 

 to 1-1 150th; ditto of tablet, not exceeding l-280th. 



76. GoNiuM punctatum. The spotted Gonium. — Body 

 composed of green corjouscles, spotted with black, and 

 enclosed within a crystalline lorica. Found amongst 

 conferva. Size of animalcule 1 -4600th; a tablet of 16, 

 1-5 70th in breadth. 



77- Gonium tranquillum. The tranquil Gonium. — Body 

 composed of green corpuscles within a crystalline lorica, 

 as shewn at figure 43. Size l-2880th; ditto tablet of 16, 

 from l-140th to l-220th in breadth. Tablet sometimes 

 twice as broad as long. 



78. Gonium hyalum. The crystal Gonium. — Body 

 composed of transparent corpuscles within a crystalline 

 shell. Found in stagnant water. Size 1 -300th ; ditto 

 tablet of 20 to 25, l-6000th in breadth. 



79. Gos ivM glaiicum. The blueish-coloured Gonium. — 

 Body composed of blueish-green corpuscles within a 

 crystalline shell. The tablets vary in the number of ani- 

 malcules — namely, from four to sixty-four. Found in 

 sea-water. Size 1 -5000th; ditto tablet, l-500th in 

 diameter. 



Genus XIX. Syncrypta. The double -loricated globe 

 Animalcules. — This genus of the family Volvocina is mainly 

 characterized by its secreting or hiding itself (as the name 



