12 OENEBAL HISTORY OF 



wise of tlio animalcule, and thus resembling tlic hmic of the naked 

 Mollusca and Annelida, as elugs, Iceclies, Ike. ; the other, stiff, rigid, 

 and hard, ha\Tng the appearance of a shell, though, from its flexi- 

 bility and transparent natiu-e, it is more like horn. The creatures 

 possessing the former of these arc tei-mcd the naked, shell-loss, or 

 illoricated Infusoria, whilst those invested with the latter constitute 

 the Im^icated. I shall, therefore, adopt the terms loricated and Uhri- 

 cated in this work, because they appeal' to be the least objectionable; 

 for, although, in etymological strictness, lorica simply means a shell, 

 yet, as we commonly attach the idea of a certain composition to the 

 word shell, it may be as well to avoid the use of it. 



In the doubtful organisms which form the large family Bacinaria, 

 the botanist employs the terms frustide, froud, and valve for the outer 

 coveiiug of those they consider vegetables. The reader will, there- 

 fore, bear in mind these several words, and is referred to the general 

 remarks on that family and its sections given tn cxtcnso in Part III. 



The Lorica differs greatly as to its composition ia different genera. 

 In some cases it is composed entirely of silica ; in others, of lime, 

 combined with carbonic acid as a carbonate, with a portion of the 

 oxide of ii'on. In some, it is destructible by heat, in others, not so. 

 There is a difference also as to the proportion of the creature enclosed 

 within the lorica. Some Infusoria are entirely encased, as in a box 

 or pitcher; whilst others are only so in part, having merely a shield 

 or carapace over them. "Wliere the lorica encloses the animal, save 

 its head and tail, as does the covering of the tortoise, it is called a 

 testa or testula ; when it covers the back only, a sadclUmn or shield, 

 as in Euplotcs, Aspidisca, Sec. The term JJrceolus applies to a gelati- 

 nous membranous or more firm external investment, having a bell- 

 glass, cyliudrical or conical figure closed at the posterior, but open at 

 the opposite exti'cmity, whence the animal may protrude itself. This 

 variety of lorica is met with in the genera Bijjlugia, Binolryon, Vagi- 

 nicola, and Floscularia. The appellation Laccrna, or mantle, is applied 

 generally to the gelatinous external membrane of the bodies of In- 

 fusoria, iacre^iBing with their increase ia size. Within this tunic the 

 animal may reproduce itself, and, for a certain time, the parent and 

 offspring possess it in common, but id'tcr a time the mantle ruptures 

 and the yoxmg escape- Thu?, at a certain period, the ] 



