182 Part III. — Sixteenth Annual Report 



The total numbers of the monthly records exhibit a greater amount of 

 divergence than those for the stations as shown by the next formula. 



Formula (2) shows the total number of records of Calanus for each 

 of the stations for the seven years, (a) for the inner stations, I., III., and 

 IV. ; (b) for the outer stations, V., VIII., and IX. ; and (c) for all the six 

 stations : — 



Names of the Months, d ,o *3 "3 %? ■■§ J5* t|> % ^ > 6 



iw«i , „„ u or «* f(«) the Inuer Stations, - - 20 27 15 32 25 14 16 14 7 22 21 27 



Record^ I for each J (6) the 0uter Stations > - - 12 30 13 30 28 15 18 16 17 22 16 27 



Month, for (^ aU ^ gix gtations> . . 32 57 2 8 62 53 29 34 30 24 44 37 54 



Yet although there is a certain amount of variation, with the excep- 

 tion of one or two months — as March and September — this variation 

 is comparatively trilling, showing that Calanus was not only common, 

 but also, on an average, very equally distributed throughout the estuary. 

 The total number of records of this Copepod for the three inner and three 

 outer stations, for the twelve months and for all the seven years, is 240 

 and 244 respectively, or practically the same for the two groups of 

 stations. Another point which may be noticed here, and which is shown 

 in the Table, is that the totals of the monthly records for the seven years 

 and for each of the six stations for April are, with one exception, exactly 

 alike— the number for April for each station being ten, except at Station 

 I., where the number is twelve. It would also appear from the tabular 

 enumeration of the records that during six out of the seven years 

 (excluding 1889) Galanus was more common and generally diffused 

 throughout the district referred to here, in the month of April, than in 

 any of the other months. The reason for this uniformity may not be 

 easily explained. It may be due to a periodic migration of Calanus, or 

 to some influence inducing them to crowd more in towards the shore at 

 this season — probably for spawning. 



Formula (3) shows the total number of records of Calanus for each of 

 the seven years, (a) for the inner stations, I., III., and IV. ; (b) for the 

 outer stations, V., VIII., and IX.; and (c) for all the six stations : — 



Numbers of the Years, - 



Total number of f&) ^ e * n f r g a ^ ons ' 



Records for eachJ ^ the 0uter Statlons ' 



Year, for (^ a}] the gix stationS; 



The greatest difference between the yearly totals for the inner and 

 outer stations is that for 1894, while the total number for the seven 

 years for each group of stations shows only a difference of four — the 

 numbers being for the inner stations 240 and for the outer stations 244. 



But though Calanus finmarchicus is the most common Copepod in the 

 Firth of Forth, there are one or two other species included in the lists of 

 tow-net gatherings which are more or less generally distributed, and at 

 times moderately frequent, and which no doubt compete closely 

 with Calanus as important sources of fish-food, especially as the food of 

 young fishes. Temora longicornis is one of these ; so also, though in a 

 somewhat less degree, are one or two species of Acartia — viz., A. 

 longiremis and A. clausii (both of which are found in the Forth estuary). 

 I do not propose to refer at length to the distribution of these Copepods, 

 as the Tables which follow show by comparison with that of Calanus 

 its more important details, as well as some other of the more noticeable 

 differences in this respect between them and that species. 



889. 



1890. 



1891. 



1892. 



1893. 



1894. 



1895, 



15 

 19 



43 

 43 



49 



48 



45 

 49 



42 

 44 



20 

 14 



26 



27 



34 



86 



97 



94 



86 



34 



53 



