Fishes of the Western North Atlantic 49 



it rasps through skin and scales by means of its horny teeth and then sucks the blood. The 

 secretion of its buccal glands has been found to have an anticoagulating action, thus help- 

 ing the flow of blood/' Its prey sucked dry, it attacks another. After metamorphosis, young 

 ones in aquaria attack any fish that may be available and doubtless older Lampreys do the 

 same. In salt water they have been found preying in this way on mackerel, shad (Alosa), 

 cod, haddock, American pollock (Pollachius), salmon, basking sharks, the various anad- 

 romous herrings, swordfish, hake (Urophycis), sturgeons and eels; as many as three or 

 four sometimes have been found fast to a single shad. Near river mouths the shad and 

 herring tribes suffer most from them. Judging from their landlocked relatives and from 

 the frequency with which they have been found attached to marine fish, they must be 

 extremely destructive to the latter when they are at all plentiful. So far as we are aware, 

 nothing but fish blood has been found in the stomachs of Lampreys at sea, except fish eggs, 

 of which they are said to be full occasionally.*^ But it is probable that they take in a certain 

 amount of solid flesh also, for muscular tissue, as well as blood, has been found in the 

 stomachs of fresh water Lampreys of another genus." 



Before its metamorphosis, the larval Lamprey in fresh water subsists entirely on such 

 microscopic organisms as may be suspended in the constant stream of water that is drawn 

 into the pharynx and discharged through the gill chambers, the oral papillae acting as a 

 sieve to prevent the entrance of grains of sand, etc. When the sieve formed by these papil- 

 lae becomes clogged, the gill openings are closed and the water is forced back through it." 

 How the food particles are separated from the water and carried into the oesophagus is not 

 definitely known.°° 



It has been known from early times that the Sea Lamprey is anadromous."'" However, 

 it does not enter all the streams within its range indiscriminately, but chooses certain ones 

 and avoids others. As an illustration, we may cite outer Nova Scotia and the Bay of Fundy, 

 where Lampreys run in the St. Marys, Sackville, Annapolis, Shubenacadie, Petitcodiac 

 and St. John Rivers, but not in the Margaree, Moser or Apple Rivers, although these 

 last are also "salmon" rivers.'" For successful reproduction this selectivity is essential 

 in order to obtain gravelly bottom in rapid water for spawning beds, as well as muddy or 

 soft sandy bottom in quiet water for the larvae. 



The mature Lampreys enter the rivers of the New England and middle Atlantic 



61. Gage and Gage, Science, N.S. 66, 1927: 282. 62. Goode, Fish. Fish. Industr. U.S., Sect, j, 1884: 677. 



63. Jordan, Guide to Study Fish., /, 1905: 491. 



64. For a detailed account of the observations on the larva of the landlocked race, see Gage (Sci. Mon., N. Y., 28, 

 1929:401). 



65. The food particles have been described as being entangled in strings of mucus and swept back with the latter 

 to the oesophagus by the ciliated tracts on the pharyngeal walls (Bridge, Camb. Nat. Hist., 7, 1904: 429). But 

 so far as we can learn this has not actually been observed. 



65a. See Fontaine (Bull. Inst. Oceanogr. Monaco, No. 848, 1942: 2) for a recent study of the osmotic pressure of 

 the body fluids of Petromyzon marinus in relation to sexual maturity and to its migrations from salt water into 

 fresh. 



66. The above statement is based on extensive observations made in connection with salmon investigations by the 

 Biological Board of Canada, communicated to us by A. G. Huntsman. 



