114 DESCRIPTION OF [Polygastrica. 



FAMILY III. VOLVOCINA. 



This family derives its name from the rolling motion 

 with which the extraordinary creatures belonging to it 

 make their way through their natural element the water. 

 The mode in which they self- divide, whilst pent up within 

 their loricated vestment, is a curious characteristic of the 

 family, and such as would almost warrant the supposition 

 that they hold some very near relationship to those re- 

 markable creatures termed Zoophites. They resemble the 

 Monads in most particulars relating to their organization. 

 The body is unvarying and destitute of appendages ? They 

 have several digestive sacs, but no true alimentary canal. 

 Whilst propagation by self- division is proceeding, and the 

 young are increasing in size, the surrounding induvium, 

 which is a distinct lorica, is observed to expand in a cor- 

 responding degree, but continues entire until they have 

 come to maturity, when it is seen to burst, and set the 

 numerous occupants at liberty. The animalcules thus set 

 free multiply in the same manner, and also by means of 

 ova in which case the expansive property of the lorica 

 comes equally into operation. 



All the genera (excepting, perhaps, the Gyges), are pro- 

 vided with organs of locomotion, which consist, as with 

 the Monads and Cryptomonads, of a single or double fla- 

 gelliform proboscis, of very delicate texture ; and hence it 

 is that, when they are in clusters, the entire heap appears to 

 be ciliated, or beset with hairs. Transparent digestive cells 

 are visible in the Volvox globator and Gonium pectorale, 



