122 DESCRIPTION OF [Polygastrica. 



belongs. The general envelope is a gelatinous substance 

 of a spherical form, and fitted up into as many compart- 

 ments, or cells, as there are individuals in its httle 

 community to inhabit. From out of these cells they can 

 severally stretch themselves a considerable distance, whilst 

 they continue fastened, in the manner before described, by 

 the extremely delicate and extensible tail. 



81. Synuba uvella. The grape Synura. — Body com- 

 posed of oblong corpuscles, of a yellow colour, and 

 capable of being stretched forth from their cells to three 

 times their natural length, by means of the extensible 

 tail. The cluster has the form of a mulberry, and its 

 motion is a rolling one, like that of the Volvox globator. 

 Figure 50 exhibits a cluster magnified, and figure 51a 

 portion of a cluster, to shew the manner in which the tails 

 of the animalcules are inserted in the common envelope. 

 This species, along with Syncrypta and Uroglena volvox, 

 may often have been confounded with Uvella virescens. 

 Length of body, exclusive of tail, 1-1 700th j diameter of 

 cluster, from 1-1 90th to 1 -280th. 



Genus XXI. Uroglena. The globe Animalcules, with 

 ray and eye. — This is the first genus of the family Vol- 

 vocina which is distinguished by the possession of both 

 the eye and tail. It is also a sort of compound ani- 

 malcule, living in clusters under a common covering or 

 mantle (Jacerna), which is apportioned into cells for the 

 accommodation of the several individuals. The self- 

 division takes place simply and equally in these individuals, 

 whilst remaining in their clustering condition. Within 

 the mantle they are placed at uniform distances from each 

 other, with their tails radiating from the centre, and by 



