1897.] NEW YORK ACADEMY OF SCIENCES. 321 



NOTES ON THE SPAWNING HABITS OP THE BROOK: 

 LAMPREY {Petromyzon wilderi). 



By Bashford Dean and Francis B. Sumner.. 



Plate XXVII, 



The following notes add a few details to the account of the 

 spawning habits of marsipobranchs given in 1893 by Professor 

 Gage in his admirable work on the lampreys of the Cayuga and 

 Seneca Lake region.* The present observations were made in 

 the uppermost part of New York City upon the brook lamprey, 

 Petromyzon (Lampetra') ivilderi, Gage. The specimens were 

 identified by comparison with topotypes kindly loaned by Pro- 

 fessor Gage. 



The spawning locality was at Lincoln Park, a few rods from the 

 station of the New York and Putnam Railroad at a point where 

 Tibbit's Brook passes under a stone-arch wagon-bridge. Van 

 Cortlandt Lake, into which the brook flows, lies about a mile to 

 the southward. In this direction the lampreys are thus shut oflf 

 from communication with the brackish water below, by the dam, 

 ten or twelve feet in height, at the mouth of the lake. Nor can 

 they well pass into neighboring waterways, as the brook arises 

 from springs in the vicinity of Bryn Mawr station, east of Glen- 

 wood. It is very probable, therefore, that the lampreys, like 

 those described by Gage, spend most of the year in a lake, as- 

 cending the brook at spawning time. 



The only spawning-ground noted was in the shade of the stone 

 archway where the brook finds its last stretch of gravelly bottom. 

 Above and below this point, the bottom was muddy and the 

 stream on the whole more sluggish. Here on April 16th, three 

 or four dozen lampreys were observed within a few square yards. 

 Many of these were engaged in spawning and nest-building. 

 Three spawning parties were noted, one of which was allowed to 

 remain undisturbed that the process could be closely followed. 



The spawning season of our local lamprey is thus found to be 

 nearly a month earlier than that at Cayuga Lake. Professor 

 Gage states that in the latter region, the process lasts approxi- 

 mately from May 8th to May 20th. 



The appearance of the lamprey's at the time of spawning is 

 shown in the accompanying plate (Plate XXVII) from a pencil 

 sketch made on the spot. Their " nest " was a small gravel-filled 



*The Lake and Brook Lampreys of New York, especially those of Cayuga and 

 Seneca Lakes. The Wilder Quarter-Century Book. Ithaca, 1893. Pp. 421-493, Pis. 



i-vn. 



Transactions N. Y. Acad Sci., Vol. XVI., Sig. 21, December 9, 1897. 



