1897.] NEW YORK ACADEMY OF SCIENCES. 323 



The extrusion of eggs and milt which instantly follows is ac- 

 companied by rapid vibration of the hinder body region of both 

 male and female, the tails directed brush-like against the sand. 

 The number of vibrations was estimated to be about ten or twelve 

 in the brief time of pairing, about three seconds. Few eggs re- 

 latively could, therefore, be extruded at a time. At this mo- 

 ment they may be seen in the water, but they speedily sink with 

 the flurry of sand. The total number of eggs found in one well- 

 distended female was calculated to be 860. 



The milt is nearly colorless, causing no cloud in the water at 

 the time of emission. The great length of the slender papilla 

 (4 mm.) suggests that an actual intromission occurs, but of this 

 there appears to be no evidence. The short duration of mating 

 and the immediate outcasting of the eggs are, it is evident, de- 

 cidedly opposed to this method of fertilization. But to deter- 

 mine by direct observation that no intromission occurs is ex- 

 ceedingly difficult; the pairing takes place unexpectedly and 

 terminates suddenly and during the few intervening seconds the 

 observer is confused by the rapidity of the movement. In a single 

 favorable instance, at the close of the vibration, the papilla was 

 seen to be separate from the cloacal opening of the female. 

 Probably, therefore, the papilla serves to direct the milt upon the 

 discharging eggs rather than as an intromittent organ. In the 

 present nest ovulation took place at irregular intervals, in one 

 case after a lapse of two minutes, but usually after a longer 

 time. In one instance a male attached for a moment to another 

 male, and frequently one would be seen to suddenly seize and 

 pull another awa}' from where it happened to be. Copulation 

 was later observed among lampreys which had been placed in 

 an aquarium. It was here also noticed that the papillte of the 

 males sometimes remained protruded for many minutes ; and in 

 separate individuals, probably of both sexes, the vibratory move- 

 ment of the tail was frequently observed when no copulation oc- 

 curred. 



Gage notes that lampreys of this species "are somewhat com- 

 munistic or gregarious and join in considerable numbers, some- 

 times eight to ten, to make a common nest." A few details as 

 to the utilization of the common nest were observed in the pres- 

 ent instance. The females did not return to exactly the same 

 spot in the nest when ovulating; they seemed in fact to deposit 

 eggs during intermission of stone-carr3ung, wherever they then 

 happened to be — usually, however, near the margin of the nest. 

 The eggs then often became attached to the sides of the large 

 stones in the neighborhood. No definite mass of rock fragments 

 was accumulated, for although the same lamprey would for a 



