BULLETIN OF THE UNITED STATES FISH COMMISSION. 351 



known of their habits that the theory cannot be pronounced absolutely 

 incorrect. There are, however, certain species of lampreys in Europe 

 which are believed to live entirely in fresh water. A similar statement 

 can most positively be made regarding our species inhabiting the Great 

 Lakes and other inland waters of North America. On the other hand, 

 many of the sea-lampreys remain in salt and brackish water through- 

 out the year. There appears, however, to be excellent evidence that 

 some of the lampreys move from brackish water into fresh for purposes 

 of spawning. 



Benecke, speaking of the habits of the river lamprey of Northern Ger- 

 many, remarks: 



" Concerning the habits of 'nine-eyes' in the sea nothing is known. 

 In summer they make their way from the Baltic into the Kurisches 

 fiaff and the Frisches Haff, and toward the end of September begin to 

 ascend the rivers, and are caught in great numbers in baskets and pots. 

 The ascent continues until January. In the upper reaches of the rivers 

 they make their appearance in the early spring, and spawn in April and 

 May in small schools in shallow places, where the water flows rapidly 

 over shingly bottom. The act of spawning has been observed by us 

 from year to year in the passage between the bridges at Braunsberg. 

 After the eggs, which are one millimeter in diameter, grayish yellow in 

 color, and entirely opaque, have been deposited in little masses, the 

 lampreys die. The development of the spawn is extremely dependent 

 upon the weather, so that during many years only, a very small brood 

 of young fishes makes its appearance. The young of this species have 

 been found by August Miiller in the Oder and the Alle, and in the 

 latter (?) the drying up of one of its tributaries near the mill at Pinne 

 gives an opportunity every year to collect hundreds of them in the 

 bottom mud. They are never found partially grown, and we must be- 

 lieve that they go back to the sea, there to attain their full size." 



Concerning the breeding habits of the brook lamprey, P. planeri, the 

 same authority writes : 



" The brook lampreys, like the allied species, feed upon little animals, 

 and are found in almost all the clear brooks in Prussia, seeming never 

 to migrate to the sea, although Yarn ell claims that he has found them 

 there. The clear gray, or grayish-yellow, eggs, which are one mille- 

 meter in thickness, are deposited in March or April. The adult fish 

 gather themselves together in companies of from ten to fifty individuals 

 to spawn in water of little depth, where the current flows swiftly over 

 rough ground. In close proximity to each other they cling with their 

 mouths to the bottom and their bodies streaming out in the current, 

 squirming like the bodies of snakes. Every once in a while the observer 

 can see a male, easily recognizable by its size and black color, seize 

 upon one of the females with its suctorial mouth, and therewith firmly 

 attaching itself to her close behind the head. The two then extend 

 themselves with a powerful backward squirm, and, while the male with 



