68 



COBTTIS. 



The head small; mouth without teeth, but with barbs on the lijis. 

 Body lengthened, with small scales Three rays in the gill membrane, 

 the aperture small; venti'al fins far beliind, and above them a sihgle 

 small dorsal fin. Abdominal fishes. 



This family, which with us bears the name of Loach, is aberrant 

 from that of the true Carps, and appears to make an approach to that 

 of Sihirns, thus uniting together species which in their general aspect, 

 as well as in habits, appear at first sight to have little in common. 

 Besides the presence of barbels at the mouth, which assimilates them 

 generally to the true Carps, Barbel, and Gudgeon, they also possess 

 the strongly toothed pharyngeal bones, and an air-bladder separated 

 into two lobes; which latter is indeed scarcely to be discerned, 

 because besides its being of very small size, it is enclosed within a 

 double bony case formed by the third and fourth vertebrae, whereby 

 it is kept almost concealed from view. It is placed immediately over 

 the entrance of the mouth from the gullet, and was only discovered 

 by the skilful dissection of an anatomist; and its office appears to be 

 more closely connected with the organ of hearing than with the more 

 ordinary function of suspending the body in water. It appears from 

 an observation by Mr. Maclelland in the "Asiatic Eesearches," that 

 the bones of the ear discovered by Professor Weber, as referred to by 

 Blumenbach and Professor Owen, (which in some of this family 

 connect the air-bladder with the organ of hearing in the brain,) in 

 the Loaches occupy the situation of this doubly-lobed vessel; and it 

 points out the near connection between the Siluridcs and the Loaches, 

 tliat the air-vessel of the former is situated in the same relative 

 situation. 



This family of Loaches is also distinguished by an abundant supply 

 of mucus on the skin, secreted from innumerable but obscure sources, 

 which are not confined to the lateral line, as in the generality of 

 the Cyprinida, but are scattered over the whole surface; and the use 

 of which is that it not only renders them more difiicult to be laid 

 hold of, but also answers an important purpose in the animal 

 oeconomy by preventing the escape of fluids necessary to their existence; 

 a remark which will apply to many other fishes besides the Loaches. 

 From experiments made by Dr. W. F. Edwards, brother of Dr. Milne 

 Edwards, it has been found that when a Chub and Gudgeon had 

 been wiped dry and weighed alive, although their gills continued to 

 beat until they were dead, yet by that time they had lost by 

 evaporation, the one a fifteenth, and the other a fourteenth of their 

 whole weight ; and other species suffered in about the same proportion. 

 But an example in which the body was immersed while the head 

 and gills were exposed to the air, remained alive for nine hours and 

 twenty minutes; and how long the Carp will continue alive, and even 

 increase in bulk, when wholly enclosed in wet moss, or frequently 

 dipped in water has been already noticed. 



