12 



POLYGASTRIA. 



observer. These beautiful little creatures might 

 be compared to wine-glasses of microscopic 

 dimension, the bells of which are fixed to 

 highly irritable stems, that are attached by 

 their opposite extremity to some foreign body. 

 These stems are endowed with the capability 

 of extending themselves in the shape of straight 

 filaments of exquisite tenuity, and on the 

 slightest alarm or irritation, of shrinking into 

 close spiral folds, so as to draw the little bell 

 as far as possible from danger. The mouth of 

 the bell is fringed with a circlet of cilia, which 

 vibrate rapidly at the pleasure of the animal, 

 causing a magnificent whirlpool in the sur- 

 rounding water, which brings nutritious sub- 

 stances that may be in the neighbourhood 

 towards the oral orifice, the situation of 

 which is nearly the same as in Stentor, above 

 described, and thus the little being is abun- 

 dantly supplied with food. The true Vorti- 

 cellse, although generally found grouped toge- 

 ther in elegant bunches, always have single 

 undivided stems ; but in the genus Carchesium, 

 the animals of which are similarly organised, 

 the pedicles sprout from one another so as to 

 have a branched or ramose appearance, while 

 in the genus Epistylis, animals similar to Vor- 

 ticella and Carchesium are met with, the stems 

 of which are quite stiff and inflexible, so 

 much so indeed that the animalcules belonging 

 to this group have obtained the name of " pil- 

 lar bells " (Saulenglockc/ien). 



The family Ophrydinida presents us again 

 with very remarkable forms of Polygaslric ani- 

 malcules, allied in structure to the Vorticellso, 

 but having their bodies inclosed in cases of 

 different kinds, of which it will be necessary 

 to give one or two examples. 



The genus Qphrydtum, (jelly-bell-animal- 

 cules,) of which the Ophrydium versatile (fig. 

 10) is an example, was regarded by the older 



Fig. 10. 



Section of a portion of the periphery of Ophrydium 

 versatile, showing the manner in which the individual 

 animalcules are implanted in the mass. 



naturalists as being a mass of vegetable matter, 

 and had the names of ulva, fucus, conferva, &c. 

 conferred upon it by different authors, until 

 Mu'ller, in 1786, first announced its real nature 

 and relationship to the vorticelline animalcules. 

 It is found under the shape of a gelatinous 

 mass of a lively or dull green colour, which in 

 consistence may be compared to frog's spawn, 

 some specimens attaining the size of four or 

 five inches in diameter; the whole forming an 

 irregularly shaped but smooth mass, which is 

 composed of many millions of distinct animal- 

 cules, each about ^th of a line in thickness, 



and about the T \jth of a line in length. The 

 space of a square line would therefore contain 

 9216 of these diminutive beings; a cubic line 

 six times as many, or 55,296; and a cubic 

 inch nearly eight millions, namely, 7,962,624. 

 In the water all these congregated animalcules 

 are disposed in close rows, something in the 

 same manner as in Volvox. On shaking the 

 mass many others show themselves within be- 

 tween the former, so as to form from three to 

 five different ranks. At first all the gelatinous 

 cells appear to be connected with the centre of 

 the mass by filamentary prolongations, but these 

 disappear as they proceed internally, so that 

 the middle seems to be hollow and full of 

 water; the whole, indeed, might be compared 

 to 'the gelatinous polyp masses (Alcyonida) 

 found upon the sea-shore, only the structure of 

 the animalcules is polygastric and not that of 

 polyps. 



In the other genera belonging to the family 

 Ophrydinidse, namely, Tintinnus, Vaginicola 

 (9, Jig. 11,) and Cothurnia, although living in 

 gelatinous transparent sheaths, and resembling 

 Vorticellae in their structure, are not associated 

 in masses, but remain permanently detached 

 and solitary. 



The family Encheliadae contains various 

 forms of animalcules, having the oral and anal 

 orifices distinct and situated at the opposite 

 extremities of the body. The different genera 

 of which it is composed may be distinguished 

 as follows : 



Enchelis, (revolving animalcule,) has its 

 body flask-shaped, (1, Jig. 11,) without any 

 cilia externally, but with a circlet around the 

 mouth, which is suddenly truncated and desti- 

 tute of any dental armature. 



Disoma, (double-bodied animalcule,) crea- 

 tures nearly resembling Enchelis in form and 

 structure, but with a double body (6, 7,j^g. 11). 



Actinophrys, (sun animalcule,) haying the 

 exterior of the body unprovided with loco- 

 motive cilia, but stuck over with setaceous ten- 

 tacula which radiate in all directions. 



Trichodiscus, (radiated disc animalcule,) re- 

 sembling Actinophrys, only the body is here 



Fig. 11. 



1, 2, 3, 4, 5. Enchelis farchnen, swallowing food. 

 6, 7. Disuma vacillans. 8. Lachrymaria proteus. 

 9. Vayinicola demmbens. 



