of the Fishery Board for Scotland. 193 
number of the records for each of the twelve months, it will be observed 
that those for February and December are considerably greater than the 
numbers for the other months; but if the numbers are separated into two 
groups to correspond with the inner and outer stations, the difference in 
the numbers for each of the twelve months for the three inner stations is 
increased, while the difference becomes less in the other group of numbers. 
This is best seen by arranging the numbers as a formula. 
Formula (2) shows the total number of records of Sagitta for each of 
the twelve months, for (a) the inner stations, I, III., and IV.; (0) the 
outer stations, V., VIII., aud IX. ; and (c) for all the six stations :— 
Names of the Months, Soe ry b A ee Gre MAS cbse) 
Se Sa oS oe eee, So 
((a) the Three Inner Stations, 19 30101615 7 911 6 1419 24 
Peer ot | (6) the Three Outer Stations, 18 80 10 18 21 17 19 17 15 20 17 26 
(SELL IE a OR CS SRL 
Month, for {(¢) all the Six Stations,  - 37 60 20 34 36 24 28 28 21 34 36 50 
There is one point very clearly brought out in connection with the dis- 
tribution of the Sagitta—viz., that, whether a comparison be made of the 
monthly numbers of records for each station or for the three inner and 
three outer stations or for them all, the numbers for February and most 
of those for December are greater than the others. This would seem to 
indicate that Sagitta was usually more common during these months than 
at other times of the year. 
It will be further observed that the highest total number of yearly 
records, viz. 79, is that for 1892, and the smallest, 31, for 1894, and that 
if the yearly records be divided into two sets to correspond with the three 
inner and the three outer stations, the results, as regards the highest and 
lowest numbers, are somewhat different. In this arrangement of the 
figures the highest number for the three inner stations is that for 1893, 
and the lowest that for 1889, while the maximum and minimum numbers 
for the outer stations are for the same years as in the former arrangement. 
Formula (3) will show these results more clearly. 
Formula (3) shows the total number of records of Sagttta for all the 
seven years ; for (a) the inner stations, I., III., and IV. ; (0) the outer 
stations, V., VIII., and IX.; and (c) for all the six stations :— 
Numbers of the Years, - - - - 1889. 1890, 1891. 1892. 1893. 1894. 1895. 
(a) the Inner Stations, 13 26 34 338 36 18 20 
eo ber of > the Outer Stations, 24 338 40 48 42 13 25 
Records for each & fs pel! Ba ow a ae 
Year, for (c) all the Six Stations, 37 59 74 81 78 81 45 
It would thus appear that Sagitta, like the majority of the other 
pelagic organisms of which there are records, are usually of more frequent 
occurrence in the Firth of Forth and its vicinity during the colder months, 
and that they were more numerous during 1891, 1892, and 1893 than 
during the other years. These again coincide with the yearly maxima for 
Parathemisto, and may be the result of a larger migration during these 
years, as was probably the case with Parathemisto, or to circumstances 
favouring a greater local increase; for though the difference in the 
number of the yearly records may be partly accounted for by the greater 
or fewer number of experiments, this does not explain the whole of it. 
Unfortunately the experiments were not carried on long enough nor so 
regularly as to indicate whether the difference shown is due to the actual 
increase or decrease of these organisms, aud whether it was temporary and 
accidental or part of a more or less regular cycle of changes in their 
migration or development. 
