126 DESCRIPTION OF [Polygastrica. 



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 5 Oth. 



Genus XXIV. SPHAEROSIRA. The 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. Fig. 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 



