ox THE ANIMALCUL.E OCCURRING IN A DROP OF WATER. 



33 



so called from their possessing certain appendages, which, when in motion, 

 give the appearance of wheels turning rapidly round. Many of these creatures 

 possess eyes, and the teeth even may be shewn distinctly by the microscope, 

 and present a very curious and interesting sight when the animal is feeding; 

 the action of grinding the food being easily observed. 



With these few general remarks I proceed at once to those of the Polygastrie 

 division, which are lowest in the scale of animal life, namely, the Ilonads. 

 Of the more simple forms of monad, innumerable individuals were observed. 

 These, even with a high magnifying power, such as six hundred diameters, 

 appear to be exceedingly minute, their usual size not being greater than one- 

 ten thousandth of an inch in diameter. 



The second family, Gryptomonadina, had its representative in Trachelomonas 

 volvocina; at least if not referrible to this species, I do not know where to place it. 



The next observed form was a very 

 beautiful and curious one, representing 

 the third family, Volvocina, the Breast- 

 plate Gonium, (Gonium pectorale.) A- 

 nother member of this family, the 

 Pandorina moi'um, was also present. It 

 will be noticed that these creatures 

 present the appearance of compound mo- 

 nads, as if made up of many individuals. 



Several forms of the fifth family, the 



Glosteiina, were also seen, as were also _ ^ 



numerous individuals of the tenth, the / j / | \\ 



Bacillaria. Gonium pectorale. 



We next come to family thirteen, Vorticellina: the most imposing of this 

 flimily, seen in this drop, was a Stentor, but which species I do not know: 

 the movements of this creature in the water are very remarkable, and well 

 repay the trouble of an 

 examination. Three spe- 

 cies of true Vorticella 

 were also present. These 

 little bell-shaped Anlmal- 

 culae are each provided 

 with a long stalk, very 



transparent, and hollow, which carries inside it a dark muscle, by which the 

 creature, at its pleasure, (and that is very often) contracts itself in an instant, 

 and its stalk as well, into a very small compass, so as to escape danger. I 

 believe we also observed Trichodina tentaculata, but the drawing made at the 

 time was hardly accurate enough to enable me to decide with any certainty. 



The fifteenth family was represented by Tncodiscus Sol. There were two or 

 three others which I imagine should be referred to this family, but, as in the case 

 of the last, the drawings were too imperfect to allow me to give them a name. 



VOL. I. F 



