282 GENERAL HISTORY OF THE INFUSORIA. 



envelope or sheath, as ' loricated,' in opposition to the rest, which he called 

 * illoricated.' These terms he has, however, employed in so loose a manner, 

 that they really possess no definite and constant meaning. For example, the 

 sheaths of encased animalcules represented by the Opliy^ydina are designated 

 loric£e, the enclosed animal, although possessing a distinct integument, being 

 considered naked, — while, again, the indm^ated closely-fitting integiiment of 

 Eivplotes and Coleps is equally styled a lorica, although so different in cha- 

 racter and relations. The term lorica could only, indeed, be legitimately 

 employed either to designate the sheaths of such animalcules as the Opliry- 

 clina, or the indiu-ated integument of others, as Coleps, — to one or the other, 

 but not to both ; to the former it is unnecessaiy, to the latter it is admissible. 



The integument of the Ciliata has generally been regarded to be in itself 

 contractile ; but it seems that this is an error, and that, in fact, it is simply 

 elastic. As such, its action must be counter to that of the subjacent con- 

 tractile layer, and be therefore the chief agent in restoring the figure when 

 the contractile force is relaxed ; at the same time its elasticity will allow of 

 considerable alterations in form, from contact and pressure of external more 

 rigid objects. To this an exception occiu^s in the case of those Ciliated Pro- 

 tozoa in which the integument is much hardened, and forms a lorica or shield. 

 This induration may be more or less extensive, so as either to cover the dorsum 

 Avith a shield-like plate (scutellum), as in Chlamidodon, or to entirely sur- 

 round the animalcule, as in Coleps, when it constitutes an " urceolus," open 

 at the ends. 



The external envelope, when thus hardened, has developed from it various 

 processes, of a more or less rigid character, which look hke spines (setae) 

 (XXiy. 284, 285), or hooks (uncini) (XXV. 344, 347), or are elongated as 

 styles (XXXYIII. 10 ; XXV. 350, 351), all which are oftentimes made sub- 

 servient to the act of locomotion, and less frequently to that of prehension also. 

 It must, however, be admitted that such processes are not confined to genera 

 in which the integument is veiy appreciably indurated, but occur where it is 

 of softer consistency — for instance, in Stylonychia (XXV. 343, 344). 



The integument is combustible and also diffluent, even when indurated, just 

 as are the softer contents, although more slowly. 



External Sheaths or Cases. — Before quitting the accounf of the common 

 integument or cuticle immediately investing the body of the Ciliated Protozoa, 

 a description of an homologous membrane, in fact, of a prolongation, dedu- 

 plication, or process of it, in the form of an external sheath or case about 

 certain fixed species, becomes necessary. 



The species so encased are either sessile or have only a short stalk attach- 

 ing them to the bottom of the case ; thus Vaginicola (XXVII. 10, 11) is 

 stalkless or nearly so, whilst Tintinnus has a more appreciable pedicle : on 

 the other hand the case itself may be stalked, as in Cothurnia (XXX. 12-16) ; 

 where this happens, the stem does not equal the length of the sheath, but is 

 short, solid, and thick, expanding upwards to its attachment with the base 

 of the latter, and frequently thrown into transverse folds and curved (XXX. 

 12, 15). It is homologous with the rigid stem of Epistylis, which it resem- 

 bles also in chemical characters. 



A very remarkable exception to the general rule of the attachment of 

 tunicated VorticelUna to the bottom of their case, occurs in the new genus 

 Lacjenophrys, in which the animalcule is suspended from the narrow aperture 

 of the sheath, so as to leave a more or less considerable space aroimd it 

 (XXX. 29-34). The margin of the head of the animal, i. e. the peristom, is 

 beneath the opening of the sheath, which has the further pecuHarity of being 

 very narrow and two-lipped (XXX. 29, 32, 34). In one species {L, nassa) a 



