614 DESCRIPTION OF {Polygastrica. 



ratus ; for it is mostly covered by clusters of oya. In Peridinium 

 tripos the seminal glands are evident. In four species, a system of 

 sensation is indicated by the presence of a red-coloured visual point. 

 The genera are disposed as foUows : — 



Lorica having stiff bristles or short spines— 1 1° ^ye Chaetoty phla. 



no transverse furrowed zone ) ^ r^ ^ -, 



\ ey« present . . . Chaetoglena. 



Lorica smooth or roiig-h — a ciliated transverse ( "" ^^^ Peridinium. 



zone present ) ^ ,.,,.. 



' eyo present Glenoamium. 



Some of the species have been found only in a fossil state ; these 

 are obtained fi'om the chalk formations in flint, but are not figored 

 in Die Infusionsthierchen, 



Dujardin constitutes a family Peridinieyis, agreeing in the main 

 with that of Ehrenberg. He thus narrates its characters : "Animals 

 without known internal organs; enveloped in a regular, resistant, 

 membranous lorica, which sends off a long flagelliform filament, and, 

 in addition, has one or more furrows beset with vibratile cilia. 



" The lorica would appear to have no opening, for foreign bodies 

 and colouring matter are not seen to enter it. Several have their 

 lorica prolonged into horn-like processes ; and some exhibit a coloured 

 point (eye speck.) They are distinguished from Thecamonadina, by 

 the ciliated furrow or fun-ows. 



" Of the two first of Ehrenberg' s genera, Dujardin observes, 

 these being without the fun-ow and vibratile cilia, and having only 

 a filament as a locomotive organ, are evidently akin to, and not to be 

 separated from the Thecamonadina, unless spines or asperities of the 

 lorica are to be taken for cilia. Again the so-called eye-speck is 

 not a suf&cient generic distinction between Peridinium and Gleno- 

 dinium ; the former genus, moreover, should only include spherical 

 animalcules, whilst those concave on one side, and exhibiting horns, 

 will rightly form a distinct genus — Ceraiimn." 



Genus Chaetotyphla. 27/e hur Animalcules. — Lorica siliceous, 

 hispid or spinous, destitute of a transverse furrow or zone, and visual 

 organ. The surface is covered with little spines and bristles, which 

 appear stronger at the posterior portion of the body. By pressing 

 the animalcule between the plates of an aquatic live-box, the lorica 

 bursts, and sets the little crcatui-e in the interior of it at liberty. 



