362 CLASSIFICATION OF FISHES. 



much trouble and expense^ had them brought from 



Germany for this very purpose. The pond loach, Cob. 

 fos-silis, is another European species^ but has not yet 

 been found in Britain ; it is larger than the last^ and 

 sometimes grows to a foot in length. "WTien the little 

 pools it inhabits are frozen^ or even dried up^ it hides 

 itself in the mud^ where its tenacity of hfe enables it to 

 live a long time : during stormy weather, like several 

 other ground-feeding fish_, it comes to the surface and 

 asitates the water. In reference to this fact, Mr.Yarrell 

 has well observed that '''' such fish as habitually reside 

 near the bottom of waters, have a low standard of re- 

 spiration, and a high degree of muscular irritability.* In 

 such animals there is reason to beheve there also exists 

 great susceptibility of any change in the electrical rela- 

 tions of the medium in which they reside." This, indeed 

 is proved by the restless movements of eels, loaches, 

 and other ground fish, during storms of thunder, &c. 

 which, as they effect a change in the electrical state of 

 the atmosphere, extend, in all probability, the same in- 

 fluence, at least in a considerable degree, to the water. 

 The pond loach, in fact, verifies this latter supposition, 

 for, according to Ehrman, it is constantly swallowing 

 air, which it discharges by the anus, after it has been 

 changed, by passing through the body, into carbonic 

 acid. Besides the peculiarity in the mode of propaga- 

 tion, as aheady remarked, which the loaches possess, 

 there are other points in their anatomy which equally 

 forbid us to class them in any other family. j\Ir. George 

 Daniell has communicated to Mr. Yarrell the following 

 pecuHarities in the osteology of the common loach, which 

 we shall here insert. '^ Attached to each outer side of 

 the first and second vertebrae is a hollow sphere of bone 

 of equal size, between which, on the upper surface, the 

 vertebrae are distinctly seen ; although the union of the 

 two spheres underneath hides the vertebrae when looked 

 towards from below. These circular bones, which are 

 hoUow, and the smooth insides of which can be seen 



* British Fishes, vol i. p. 22. 377. 



