2 A. E. HEFFORD. 



The observations which form the subject of the following notes deal 

 with only part of the total material on which my studies of teleostean 

 reproduction, pursued during the last two years, have been made ; but 

 as the other and larger part of the material consists of preserved 

 specimens of the young (chiefly post-larval) stages of fishes collected 

 during the four years 1906 to 1909 inclusive, it is more convenient to 

 deal with the egg collections of the past year first and to treat tlie 

 whole collection of young fry separately in a further paper. 



Systematic examination of tow-nettings for pelagic fish-eggs began 

 on February 11th, and in the early months before the steamer was in 

 commission, owing to the exigencies of weather and time which attend 

 the use of a small sailing-boat, samples were taken only inside the 

 Sound or in its near vicinity. As will be seen from the analysis of the 

 collections given in Table I, there was a break of more than a month's 

 duration, beginning early in March. From April to the end of August 

 the s.s. Oitlwna was available, which not only rendered collections from 

 the open-sea areas possible, but also permitted the use of the Petersen 

 young-fish trawl, by which large quantities of fish-eggs could be 

 obtained. The quantities so obtained were generally much too large 

 to admit of their individual examination, and therefore it was my 

 practice to pick out a portion of the total eggs for careful examination 

 and frequently for hatching in the laboratory, while the residue was 

 scrutinized as carefully as possible so that the rarer specimens should 

 not be omitted. After a certain amount of practice one can recognize 

 many of the familiar species by size and other peculiarities even with 

 the naked eye, so that after a confirmatory microscopic examination it 

 is possible to obtain a fair knowledge as to the identity of the majority 

 of the species present in a plankton sample, and then exceptional eggs 

 can often — though not, of course, without exception — be discerned. In 

 the case of tow-net samples, which were taken with coarse (24 strands 

 to the inch) or medium (50 strands to the inch) nets at various depths 

 from the surface to about 9 or 10 fathoms, care was taken to pick out 

 every individual egg. The hauls were in most cases of 15 minutes' 

 duration, so that quantitative comparison is to some degree possible. 

 Throughout this work I have conducted my observations having in 

 view practical fishery questions — e.g. the locating of spawning areas, 

 the duration of the spawning period, and the relative extent of the 

 breeding of various species of fishes in the Plymouth area — rather 

 than details of purely biological interest, and therefore my records of 

 the characters of eggs and larvae have had special regard to points for 

 purpose of ready identification at the various stages of development ; 

 hence details of embryology have little place in this paper. 



