4:2 S 



THE FRKSII-WATEU FISHES OF ErROPE. 



but there is usually an interspace between them ; their height varies, and the 

 second dorsal is sometimes higher than the body beneath it. The anal fin is 

 more developed in the female than in the male, being in the latter a mere ridge 

 which prolongs the line of the caudal. The vent is nearer to the head than in 

 the L;iin[)ern. The skin oE tlie whole body shows annular transverse markings. 

 The colour does not differ from that of the Lampern, except that the back is 

 more frequently olive-green. 



This species spawns in March or April. The eggs are yellowish-brown, 

 one millimetre in diameter. After spawning, the old fishes probably die. 



209. — TETROMYZOX URAXCHIALIS (LIX.N.i'vm). 



August IMtiller traced the development of the young, which are hatched in 

 eighteen days, and found that they were identical with the fish which had 

 been named Ammocmfe.^ hranclnal'n. At first there are eight branchial slits, 

 but the first aperture is soon obliterated. The young bury 

 themselves in the mud; and grow slowly. 



They are as well known in the north of Germany as the 

 Pride, but though they are eaten in some places, are g-enerally 

 used only as bait. In Austria the fish is known as Uhlen, 

 and in Germany as Qiierder. 



In the larval state the head is remarkably small, and the 

 length to the first gill-aperture is no more than the height 

 of the body, and is one-fifteenth of the total length, or a 

 little less. The eye is extremely small, and is hidden in the 

 thick skin of the head so as to be scarcely visible, and the eyes are separated 

 by twice the orbital diameter. The nasal aperture is triangular, and has an 

 elevated margin. The upper lip forms two-thirds of a circle, and reaches 

 forward in front of the lower lip. There is no trace of the fringe to the lip 

 which is so characteristic of the mature animal. The inner surface of the upper 

 lip is covered with papillae, behind which there is a fringe of more or less 

 branched barbels at the entrance to the throat. There are no teeth. The gill- 

 apertures are small, half-moon-shaped, and lie in a longitudinal furrow. The 

 whole body is marked with transverse rings. The dorsal fins are low and have 

 fine rays. The caudal fin is prolonged to the vent as a membranous ridge. The 

 The skin of the abdomen is transparent. The largest 



Fig. 210. — I'KTKO- 



MYZOX BUAXCIII- 

 ALIS, HEAD .SEEN 

 PKOM UELOW. 



