126 



LOWER VERTEBRATES. 



rounded by rather long barbels. The body is usually covered with small scales, the 

 pharyngeal teeth are few in number, and tlie air-bladder is enclosed in a bony capsule. 

 Many of the species are provided with an erectile spine below the eye. 



The loaches are bottom fishes, feeding on insects and worms, and often burying 

 themselves in the mud or sand. They often lie quiescent for a considerable time, 

 moving very quickly for a little distance when disturbed, in a manner not unlike that 

 of the darters and gobies, which occupy a similar position in American waters. 



Some species of loach are found in most Eurojjean sti-eams, but none occur either 

 in America or Africa. The commonest European species is Nemachilus barbatula. 



The largest family of fishes is that of Cypuinid.k, the carp family. It comprises 





upwards of one hundred and seventy-five genera and neai-ly two thousand species, found 

 in the rivers of all ]3arts of the Morld excejit South America, Australia, and the Polar 

 regions. To this family belong the various fishes which have received the vernacular 

 names of carp, chub, dace, roach, minnow, bream, and shiner. Among the Eventog- 

 nathi, they are distinguished by the following characters : The premaxilkries always 

 form the entii-e margin of the upper jaw : the mouth is always toothless ; the lower 

 pharyngeal bones are falciform, nearly parallel with the gill arches, and each provided 

 with a small number of comparatively large teeth. These teeth are arranged \n one, 

 two or three rows, the main I'ow containing from four to seven teeth, the other rows, 

 if jiresent, from one to three. The teeth of the main row are in some cases coarse 

 and blunt, forming molars. In other cases, they are slender and straight, with a 

 narrow groove (grinding surface) on the inner cutting edge towards the point. In 



