The Lake and Brook Lampreys of Nezv York 427 



true, anadroinous sea lamprey developed the peculiarities 

 found in the lake lampreys at the spawning season, and ac- 

 cording to Seeley ('86) also present in the European marine 

 lamprey during the breeding season.* Until these questions 

 could be satisfactorily answered there would remain doubt as 

 to the really constant peculiarities developed in the lake form. 

 During the winters of 1875 and 1877 large lake lampreys were 

 obtained of both sexes, and concerning them the notes either 

 say "no ridge" or "ridge very low and broad," so that addi- 

 tional information must besought. In the autumn and winter 

 of 1886-87 great inducements were offered to the lake fisher- 

 men to obtain large lampreys. During that winter and since 

 then throughout the year, large specimens were obtained and 

 brought to the University. All of these large specimens 

 looked alike. There was no dorsal ridge in any of them nor 

 was there an anal fin or projecting urogenital papilla in any 

 of them, and the two dorsals were well separated in all (PI. 

 Ill, fig. 6). It was only on dissection that the sexes could be 

 distinguished. Thus it was definitely determined during the 

 autumn and winter of 1886-87, that it was only during the 

 .spawning season that the special external sexual characters 

 appeared in the lake lamprey. 



In answer to the second query concerning like seasonal pe- 

 culiarities in the true marine lamprey : alcoholic specimens 

 obtained at various seasons were examined, but as stated 

 above, whether or not a ridge was present during life is not 

 easy to determine from alcoholic specimens. So that while 

 ridges appeared on some of them, it was found by dissection that 

 the animals were in some cases males, but quite as often females. 

 Uncertainty must therefore continue until a considerable num- 

 ber of fresh specimens could be examined. This was made 

 possible by the intelligent aid given by Mr. Thomas S. 

 Holmes, of I,awrence, Mass. , who sent specimens of the marine 

 lamprey which were running up the Merrimac River to spawn. 

 The specimens were usually sent in the early or middle part 



* During the month of August, rSSg, the writer saw in the aquarium of 

 the Trocadaro in Paris several large marine lampreys, some of which pos- 

 sessed very prominent dorsal ridges. 



