170 



Part III. — SLvteenth Annual Report 



(e) Amphipoda. 



We shall now proceed to consider the Amphipoda recorded in the lists 

 of tow-net fauna, and at the very outset we meet with a marked differen- 

 tiation in regard to the distribution and numbers of certain of the species. 

 Twenty-two species of the Amphipods mentioned in the lists of tow- 

 net gatherings are more or less fully defined by name. The distribution, 

 as regards the numbers and the frequency of three of the species, is so 

 different from the others as to indicate a more or less decided difference 

 in their habits and mode of life. The three species I refer to are Hyperia 

 galba, Hyperoclie taiLriformis (Spence Bate), and Parathemisto ohlivia. 

 Moreover, while these three differ more or less distinctly from the other 

 Amphipods mentioned in the tow-net lists, they are also in their own 

 habits somewhat dissimilar to each other. Parathemisto, for example 

 (and perhaps also Hyperoche), is to a large extent a free-swimming 

 species ; on the other hand, the HypericB are also characterised as mess- 

 mates of large Medusae, and live a considerable part of their lives 

 under the shelter afforded them by these curious organisms. Hence the 

 distribution of Hyperia in the Firth of Forth depends to some extent on 

 the presence or absence of Medusas, whereas Parathemisto being a " free 

 swimmer," its movements are not so limited as those of the other. 



The following is a list of the Amphipods referred to by name in the 

 lists of tow-net fauna : — 



Hyperia galba (Montagu). 

 Hyperoche tauriformis (Bate). 

 Parathemisto ohlivia (Kroyer). 

 Putliemisto (?) compressa (Goes). 

 Callisoma crenata (Bate). 

 Hippomedon deiiticulatus (Bate). 

 Bathyporeia sp. 

 Ampelisca sp. 

 Stenotho'e marina (Bate). 

 Argissa hamatipes (Xorman). 

 Metopa alderij Bate. 

 Periocidodes longimanus (Bate). 



Iphimedia obesa, Rathke. 

 Apherusa bispinosa (Bate). 



„ borealis (Boeck). 

 Paratylus sicammerdami (M. 



Edw.). 

 De:camine sp. 



Melphidvippella macera (Xorman). 

 Amathilla homari (Fabr.). 

 Gammarus sp. 



Gammaropsis eryth rophthalma, 

 Lillj. 



Par iambus typicus (Kr.). 



As it is not my intention to describe in detail the distribution of all 

 the Amphipods named in the list, I shall confine my remarks chiefly to 

 the Hyperiidte, because of their great importance both numerically and 

 as fish food. 



Hyperia galba. This Amphipod is occasionally present in the Firth 

 of Forth, but usually in limited numbers, and the records of its occurrence 

 seem to indicate that it is as frequently captured by the bottom tow-net as 

 it is by the surface net. In 1889 the records of it for the selected 

 stations are very few. It is recorded in the bottom tow-net lists for July, 

 and again in November. The November record describes it as common. 

 It is recorded for Station Y. in August and November, and described as 

 frequent in the bottom tow-net gatherings and few in the November 

 surface-net gatherings ; and it occurred sparingly in the bottom tow-net 

 gatherings from Stations YIII. and IX. in August. But the infrequency 

 of the records of this and other species in 1889 is no doubt partly due to 

 there being no lists of tow-net fauna for March, April, and May (with one 

 exception — viz., for Station Y. for surface net in ^lay), and for nearly all 

 the months of October and December. In 1890, though there are frequent 



