No. 552] 



THE SEA LAMPREY 



737 



however, merely absorption in the work of nest-build- 

 ing, and not that the lampreys are insensible to this 

 stimulus. 



The eyes of lampreys in the water shine like black 

 beads; but they are not very sensitive. If one meets a 

 lamprey swimming toward him in the river, it will come 

 almost right up before it will discover the person and 

 turn aside. 



Many of the movements of the sea lamprey on the 

 nest are purposeless— as was noted also for the brook 

 lamprey by Dean and Summer ('97). Thus a lamprey 

 will sometimes pick up a stone outside the nest, carry 

 and drop it into the nest; or while carrying out a stone, 

 will drop it half way up the side of the nest. It will tug 

 at a large stone which it cannot possibly dislodge, or at 

 a log, in an effort to drag it out of the nest, and will 

 repeat this again and again, without profiting in the least 

 by previous failures. On the whole one has a feeling 

 that the lamprey possesses a very low mentality even 

 as compared with fishes. 



ANNOTATED BIBLIOGEAPHY 

 rhe following list includes all the papers I have been able to find that 

 il with the spawning habits of lampreys. Those having to do with the 

 ology of fertilization are listed in Ziegler's text -book referred to below. 



137, pp. 



Carried embryos as far as the blastula stage— "en plongeant 

 et maintenant les oeufs dans des solutions de saccharose a 5 on 

 6 pour 100 ou dans des solutions isotoniques de NaCl." 

 i, John. 



A lamprey's nest. The Century Magazine, XXV, p. 457. 



Observed Petromyson marinus spawning in a creek. Describes 

 their mode of transporting stones; their indifference to an ob- 

 server at close range; but does not describe the nest, nor appar- 

 ently recognizes the purpose for which the stones are transported. 

 The female is the larger of the two. "In June it is not unusual 



