92 THE FRESH-WATER FISHES OF EUROPE- 



parallel rows placed behind each other. The hinder row is shorter and un- 

 broken ; but in the front row there are interspaces between the teeth. There 

 are two small patches of smaller sickle-shaped teeth on the vomer. The tongue 

 is short, thick, triangular, and toothless. The gill-rakers constitute four 

 comb-like arches. Their teeth-like processes are short, curved, blunt, and 

 distant. When the gill-aperture is closed, a rod-like process of skin is seen 

 to overlap it on each side. There are sixteen branchiostegal rays. 



The superior contour from the head to the tail is comparatively straight. 

 Behind the dorsal fin the breadth of the back diminishes steadily to the tail. 



The short and feebly-developed dorsal fin is intermediate between the 

 pectoral and ventral fins. The pectoral fins are fan-shaped. The first ray is 

 bony and strong, but not serrated. The ventral fins are similar, but shorter ; 

 they reach back over the vent to the anal fin. The anal fin occupies the entire 

 space between the vent and the caudal fin, but remains distinct, and its rays 

 maintain a nearly even length throughout. Close be'hind the pectoral fin, and 

 over its root, is a remarkable narrow aperture, which penetrates apparently 

 between the pectoral muscles ; but Von Siebold observes that although these 

 apertures have been detected in many Siluroids, no one has suggested any 

 purpose in the economy of the fish which they serve, though Heckel and Kner 

 describe the walls of the cavity as well supplied with nerves. 



The lateral line runs near to the back, and can be distinguished down to 

 the caudal fin. The branch of the cephalic mucus-canal running along the 

 lower jaw is marked by a row of large pores. Behind the vent there is 

 a long perforated papilla, on both anterior and posterior aspects of which there 

 are apertures which the papilla divides. The tail of the fish is remarkably 

 compressed and relatively long. 



The colour of the skull, back, and the edges of the fins, especially the 

 ventral and anal, is nearly blue-black. The sides of the body are greenish- 

 black, becoming paler towards the belly, and spotted with olive-green. The 

 belly may be of a reddish tinge or yellowish-white, with blue-black marbling. 

 There is a clear yellow band in the middle of the ventral and pectoral fins. 

 The upper jaw barbels are white on the under side ; those of the lower jaw 

 are reddish. In old age all the fins acquire reddish borders. 



Next to the Sturgeon, the Silurus glanis is the largest and heaviest fresh- 

 water fish in Europe. It is often from six to nine or ten feet long, and occa- 

 sionally reaches a length of thirteen feet. In the Danube it often attains 

 a weight of four hundred to five hundred pounds, and in South Russia may 

 exceed six hundred pounds. With age it increases chiefly in circumference, 

 and sometimes is as much as two men can span. 



It is found in rivers and lakes, and prefers quiet depths with a muddy 



