CHONDROSTOMA POLYLEPIS. 205 



reaches back to the anterior nares. In old specimens the length of the snout 

 is twice the diameter of the eye. The frontal interspace is convex, widens 

 with age from one and three-quarters to two and three-quarter times the 

 diameter of the eye. The dorsal fin is opposite the ventral, in the middle of 

 the body ; but is farther back in the young. It is higher than long ; the free 

 margin is concave. The base of the anal fin is longer, but its height is less. 

 In proportion and character it resembles the dorsal. The ventrals do not 

 reach back to the vent, but end four scales in front of the genital papilla. 

 The pectoral fin is a little shorter than the head. The caudal is deeply forked, 

 with the lower lobe rather longer than the upper, and is longer than the head. 

 The scales are firmly adherent, and have a fan of twenty rays at the free 

 margin. The larger scales are longer than high, and about two-thirds of the 

 diameter of the eye. There is an elongated scale at the base of the ventral fin. 



Chondrostoma willkommii (STEINDACHNER) . 



D. 12, A. 12, V. 10. Scales : lat. 6367, transverse - 



4 5 



There is but little difference in form of body and mouth between this 

 species and Chondrostoma polylepis ; but there is a constant difference in the 

 greater number of pharyngeal teeth, which are on each side 6 6 (Guadal- 

 quivir), or 7 6 (Guadiana), though in the latter river the formula 6 6 is 

 sometimes found. The body is compressed, with the ventral contour rather 

 more arched than the dorsal profile. The snout is usually conically pointed, but 

 in old fishes it becomes very blunt. The transverse cleft of the mouth is slightly 

 curved, its width is about the diameter of the eye, but it widens with age to 

 one and one-third times the orbital diameter. The eye is usually one-quarter 

 of the length of the head, but in old individuals the head length is four and a 

 half times the diameter of the eye. The breadth of the frontal interspace 

 between the orbits is one and three-fifths to twice the diameter of the eye. 

 The length of the snout only slightly exceeds the diameter of the eye. The 

 relative length of the head is much the same as in Ck. polylepis ; and the fins 

 are very similar in proportion and character. Along the lateral line, which is 

 parallel to the abdomen, there are usually 64 to 66 scales. The free posterior 

 border of a scale may be a little pointed or rounded; it has numerous 

 diverging rays. 



The fish is found in great numbers in the Guadiana and its tributaries, and 

 is plentiful in the Guadalquivir at Cordova, though rare in that river at Seville. 

 The back is dark bluish-grey, or brown in muddy streams. Sometimes there 

 is a trace of a blue-grey longitudinal band in the middle of the body. 



