240 THE FRESH-WATER FISHES OF EUROPE. 



jaw being beneath and overlapped by the projecting upper jaw, and covered 

 by its lip and barbels, so that the mouth aperture is not seen. There 

 are four barbels at nearly equal distances on the upper jaw, and a longer 

 barbel at each angle of the mouth. On the under jaw there are two short 

 barbels in front on each side of the median symphysis. The barbels at the 

 corners of the mouth are little less than half the length of the head ; 

 so that the barbels on the lower jaw decrease in length anteriorly. The 

 eye is very small ; its diameter is less than one-seventh of the length of the 

 head. It is placed high up, is separated from the other eye by twice the 

 orbital diameter, and is more than this distance from the snout. The sub- 

 orbital spine is completely covered by the skin ; and, though its position 

 may be detected, it is not erectile. 



The nares are divided, are placed near to the eye, and the anterior narine 



Fig. 140. MISGVKNUS FOSSILIS 



forms a short projecting tube. The gill-aperture is completely closed on the 

 throat, and only open laterally from the level of the eye to the base of the 

 pectoral fin. 



All the bones of the face and operculum are covered with skin. The sub- 

 orbital ring is seen to be well developed in the skeleton, and has a strong spine 

 behind. 



All the fins are more or less rounded at their free borders. The dorsal, 

 which is opposite to the ventral fin, begins behind the middle of the body. Its 

 height is less than the height of the body. The anal fin is similar to the 

 dorsal in length, height, and form, and commences some little distance 

 behind the vent. The rays of the pectoral fin are as long as the anal fin 

 rays. The ventral fins are shortest, and do not reach to the vent. The middle 

 rays of the caudal are longest, and exceed the length of the head. The caudal 

 fin consists of fourteen jointed rays, with an unjointed terminal ray on each 

 side ; in front of which there are about twenty truncate rays, which reach far 

 up the tail, forming an edge or membranous ridge in the vertical median 

 line both above and below. A somewhat white line extends on the abdominal 

 surface from the throat to the prominent vent. The lateral line extends 



