TEE INTELLECTUAL OBSERVES. 



JULY, 1864. 



THE NATURAL HISTORY OF THE HAIRY-BACKED 

 ANIMALCULES (CH^TONOTID^E) . 



BY PHILIP HENRY GOSSE, F.R.S. 

 (With Two Plates.) 



Whoever lias been in the habit of collecting the floccose matter 

 that accumulates around the submerged stems of aquatic plants, 

 or the impalpable sediment that lies at the bottom of still pools 

 and running ditches, and of examining the same in the live- 

 boxes of his microscope, is aware how abundant and how 

 various are the forms of life that are presented to his view. 

 Creatures the most strange and the most incongruous — odd in 

 their shapes, odd in their structure, odd in their manners, odd 

 in their movements, swim, or rotate, or creep, or wriggle over 

 the field of vision, till the little pellet of brown mud, no bigger 

 than a grain of duck-shot, flattened out before him, proves a 

 complete microcosm. Many such pellets will not have passed 

 under the eye of the curious observer before he will pretty 

 certainly have become familiar with a little creature of attrac- 

 tive appearance and lively manners, which forms the typical 

 representative of a limited group of animals, whose family name 

 I have set at the head of this article. Dr. Ehrenbcrg, of Ber- 

 lin, named it the Bristle-fish (Chcetonotm) , both of which 

 appellations allude to the long and stout bristles with which 

 its back is beset in rows. Its movements are not so rapid as 

 those of many animalcules, and therefore it affords a fair object 

 for the young microscopist, whilo its form is so peculiar as to 

 be easily recognized. When enclosed in an aquatic live-box, 

 it is fond of crawling on the surface of the glass cover, whereby 

 we distinctly see the ventral surface, as we see the lateral form 

 when it creeps about the stems. The form, when seen ver- 

 tically, is somewhat fish-like, with a thick, blunt, and rather 

 triangular head, and a slight constriction or neck ; a swelling 

 body, terminating in two diverging points. The figure, when 

 vol. v. — NO. VI. D D 



