126 DESCRIPTION OF [Poly(/astrica. 



bodies may be seen connected together by means of an 

 intervening membrane, formed of dead colourless Infusoria, 

 and the remains of loricse. Size 1-5 50th. 



Genus XXIV. Sphaerosiba. T7ie rudder Animal- 

 cules. — The distinguishing features of this genus are its 

 being deficient of the tail, but possessing the eye, and 

 a simple filiform rudder-like proboscis. Its method of 

 self- dividing is different from that of any of the preceding 

 genera, inasmuch as it occurs unequally within the enve- 

 lope, when young clusters are formed at once from the 

 parent ones. This genus differs, then, from the Pandorina 

 in having the eye ; from the Eudorina by its unequal mode 

 of self-division ; and from the Volvox by its simple 

 proboscis. Self-division in these creatures takes place in 

 the longitudinal direction, commencing in equal planes, so 

 that lamina are produced as with the Gonium. 



85. Sphaerosira volvox. The revolving Sphaerosira. — 

 Body composed of pale green corpuscles, of nearly a 

 globular shape, enveloped in a lorica of the mantle form. 

 Eye bright red. The cluster resembles a great ball of 

 animalcules, containing small compressed clusters within 

 it. Fiff. 49 represents a portion of the tunic or lorica, 

 highly magnified, so as to shew the different forms of the 

 creatures located within it, namely, three single animal- 

 cules, one mulberry- shaped cluster, and one oblong group 

 may be observed within that portion of lorica. Figure 

 48 represents a large spherical cluster. Found in con- 

 siderable numbers in company with the Volvox globator, 

 and often attains its size. Sometimes found by itself. 



Genus XXV. Volvox. The globe Animalcules. — The 

 genus Volvox, which is the type of the family Volvocina, 

 was instituted by Linneus, and promulgated to the world in 



