136 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



fishing not practiced at Cherrystone ; an abundance of spawners, it was 

 found, were taken under the above conditions at the former place, and 

 it was believed, from observations made at the time, that many millions 

 of eggs might be obtained there in a single night. From this it appears 

 that what is now needed to make the artificial incubation of the mack- 

 erel a success is to choose son^e point for our operations where the fishing 

 is carried on at ni^lit or in the evening. In relation to this part of the 

 subject the "^^riter will forbear to say anything further, as its discussion 

 rightfrJiy belongs to Colonel McDonald, whose observation it is ; but I 

 liave been informed by Professor McCloskie, of Princeton, that while 

 he was in company with Mr. J. S. Kingsley, during the present summer, 

 on the Massachusetts coast, in the vicinity of Cape Ann, the latter gen- 

 tleman conducted some observations on floating fish eggs which were 

 taken at night in a tow-net and believed to have been laid after sun- 

 down ; they were not identified, however. ( )va which were found float- 

 ing at the surface of the sea by Professor Haeckel,* at Ajaccio, oft" the 

 island of Corsica, and afterward at Kice, were agglutinated together in 

 clumps, but the species was not determined, and it was only sui)j)osed 

 that they belonged to some gadoid, and are hence doubtfully referred to 

 Motella. Edward Van Beneden t also, who describes at some length 

 similar adhesive floating ova, which he had obtained in the same way, 

 with the help of the tow-net, off Villafranca, does not identify them, 

 nor does he state definitely at what time of day it was supi)osed they 

 were spawned, but from the evidence aftorded by his time record of the 

 rate of their segmentation I am, nevertheless, prepared to believe that 

 they were laid at night. The Cyprinodonts in the si)awning season, as 

 far as my observations go, are much more actively engaged in amatory 

 play in the night than at other times, judging from the rapid motions 

 and splashing noise which they make in the water during this part of 

 the day. G. O. Sars, in his account of the development of the cod, says 

 nothing in regard to the time of day at w^hich this fish parts with its 

 ova, but the writer believes that there are strong grounds for a belief 

 that the bonito, or crab-eater {Elacate canadus), is a nocturnal spawner, 

 the same as the mackerel, from the circumstance that it was only from 

 individuals caught in the evening that ova were obtained, which api)ears 

 to be the case also, judging from our experience, \vith the moon-fish {Fare- 

 phippus fciber). The foregoing data, although not all of them directly 

 bearing upon the question of the time at which the Sx)anish mackerel 

 discharges its spawn, are sufiQcieutly within the scope of the evidence 

 needed to help us to reach a conclusion in regard to the matter so that 

 we will know how to proceed in the future. The artificial incubation 

 does not appear to be the gravest part of the problem to be solved j the 



t *Die Gastrnla iiud die Eifurcliimg der Thiere. Jeuiiisclie Zeitsch., IX, 402-508, 

 1875, 7 pis. 



t A contributiou to the history of the embiyouic development of the Teleosteans. 

 Quar. Journ. Mic. Sci., No. LXIX, 41-57, 1 pL, 1878. 



