176 Part III. — Sixteenth Annual Report 



and they either remained in the estuary all the summer or returned in the 

 autumn, for they were observed again in November. 



Whether this irruption of the Hyperiidae was merely accidental and 

 temporary, or due to a periodic migration at more or less distant inter- 

 vals of time, the records are not sufficiently extensive to show. Whatever 

 be the reason, there seems to be no doubt that some time during 1891 and 

 1892 there was a greater number than usual of these Crustaceans off our 

 East Coast, part of which found their way inshore, with the result that 

 the number of records of Parathemisto was increased beyond those of the 

 previous or following years. 



In the following analysis of the Table, some of the results referred to 

 are more clearly brought out— the three formulae subjoined show the 

 total numbers of the records (1) for the stations, (2) the months, and (3) 

 the years, thus : — 



Formula (1) shows the total number of the records of Parathemisto 

 for each of the stations for all the mouths and years : — 



Numbers of the Stations, - - - I. III. IV. V. VIII. IX. 



Total number of Records for each Station, - 37 39 31 36 36 29 



Formula (2) shows the total number of the records of Parathemisto 

 for each of the months for all the years, (a) for Stations L, III., and IY. ; 

 (b) for Stations Y., YIIL, and IX. ; and (c) for all the six stations : - 



Names of the Months, a ^ % "g K . g ir rj» bp- -g. ^j > 6 



Tntal unTnW nf ((«) the Inner Stations, - 16 18 10 15 7 3 5 7 1115 



KecOTdsfo* <M&) the Outer Stations, - 10 20 8 14 6 3 1 2 9 8 20 



each Month, for (^ aU the gix stationSj . 26 38 18 29 13 6 1 7 16 19 35 



Formula (3) shows the total number of the records of Parathemisto 

 for each year, for (a) the inner stations, I., III., and IY. ; (b) the outer 

 stations, Y., YIIL, and IX. ; and (c) for all the six stations : — 



Numbers of Years, - - •- - 1889. 1890. 1891. 1892. 1893. 1894. 1895. 



Total number of ((«) the Inner Stations, - 2 4 34 27 17 14 9 



Records for \ (6) the 0uter Stations > " 6 V1 20 33 17 6 7 



each Year, for (^ &n ^ Six stationSj . g 16 54 60 34 2 16 



Euthemisto compressa. This species (referred to above) was recorded 

 for the first time in the Firth of Forth in the " Tenth Annual Report of 

 the Fishery Board for Scotland," from specimens obtained at Station Y. 

 in February 1892. It was collected again in the same year in November ; 

 and the next record of it is in November 1893, when it was obtained at 

 Station Y. 



The other Amphipods mentioned in the list are, with the exception of 

 Paratylus and Apherusa, only occasionally referred to among the records 

 of tow-net invertebrates, and are therefore, except from a natural history 

 point of view, of less importance than those already mentioned. 

 Consequently I do not propose to enter very minutely into the 

 consideration of their distribution.* 



Callisoma crenata. There are few records of this species, and they 

 extend from 1890 to 1895. 



Hippomedon aenticulatus is only recorded once among the tow-net 

 lists for the selected stations — viz., for Station IX. in February 1894. 



* A tabulated list of species at the end of this paper shows some further details of the 

 distribution of these Amphipods. 



