THE SAND-PIPER. 145 



THE LAMPERN, OR RIVER LAMPREY (Petromyzon fluvlatUis). 



In the River Lamprey the skull is cartilaginous below, and in front carries a considerable mass 

 of labial cartilages. The neural arches may be represented by cartilages. The maxillary tooth has a 

 broad base with a cusp at each extremity, and the 

 mandibular tooth is a corresponding plate with seven 

 to nine cusps, which are relatively smaller than in 

 the Sea Lamprey. It is a much smaller fish than 

 the latter, and is commonly from a foot to fifteen 

 inches long. It lives on insects, worms, and small 

 fishes. It abounds in the Thames, from which for- 

 merly a million Lampreys were taken in a year. It 

 is met with in the Severn, and has a wide distribu- 

 tion in the rivers of Europe, and occurs in some of 

 the lakes of North Italy. It is also found in North 

 America and Japan. The ovaries, according to Heckel 

 and Kner, extend the entire length of the abdomen. 

 The intestine does not enlarge into a true stomach. 

 This fish is chiefly valued for bait, being tenacious 

 of life, so that it can be kept alive at sea for some 

 weeks. It is sold at from 3 to 5 a thousand. 



Ivl > hi*. 1,.\ >1J ! i i. i . 



When pickled, it is imported from Holland for 



the German, inhabitants of Soho. The colour is dai-k bluish on the back and silvery on the sides. 



THE SAND-PIPER (Petromyzon branchial is). 



This species is often called the Fringe-lipped Lamprey, because the circular lip is furnished with 

 numerous papilla?. It is shorter and relatively thicker than the River Lamprey. Its teeth are much 

 blunter, but otherwise similar to those of Petromyzon fluviatilis. The dorsal fins are deeper, but 

 separated by a notch. It is common in the rivers of Europe and of England, and occurs in the 

 western parts of North America. Its habits are very similar to those of the other fresh-water species, 

 which it resembles in colour. 



The young of this species is sometimes called the Mud Lamprey, or " Stone Grig." The upper lip 

 is then remarkable for its horseshoe shape ; the mouth is incapable of adhering to stones. The fish 

 hides in the mud and loose sand at the bottom of brooks. It is said to be devoured in great numbers 

 by the Eel. The eggs are hatched in eighteen days, when the young fish are white. At first there 

 are eight branchial slits, but the front one soon disappears. Before the mouth comes into existence 

 there is an oval vesicle in its place, and there is no separation in the young between the alimentary 

 canal and the branchial organ. The respiratory canal is usually not completed till the end of the 

 fourth year, when the metamorphosis takes place, occupying a period of about ten days. The teeth 

 then develop, the intestine becomes shorter, the eyes become more perfect, and the Lamprey's food 

 is changed from microscopic organisms to such animals as have been mentioned. With the 

 shortening of the intestine the body itself shortens, so that the mature fish is often smaller than the 

 immature' form. Having become a Lamprey, it puts on a silvery appearance and moves into clear 

 water. It is probable that having reached the perfect state it spawns but once. No other fish 

 presents so remarkable a transformation. 



Other species of the genus are found in British Columbia and in Buenos Ayres. One or two allied 

 genei-a have a curious geographical distribution. The Geotria chilensis, a species about two feet long, 

 which has a pair of long, pointed, lingual teeth, compared by Dr. Giinther to the horns of a young 

 Antelope, is found in New Zealand, the Swan River of Australia, and in Chili. .The Mordacia 

 mordax occurs in Chili and Tasmania, and has two pairs of serrated teeth on the tongue. 



FAMILY II. MYXIXID.E. 



The Myxinoids closely resemble the Lampreys in having a naked Eel-shaped body ; the nostril 

 similarly has a single aperture at the extremity of the head, but, unlike that of the Lampreys, the nasal 

 209 



