262 Appendices to Sixth Annual Report 
on the other hand, like the Calanidz among the Copepoda, and the 
Hyperilide among the Amphipoda, pelagic in their habits. The phospho- 
rescence of the seais also apparently to some extent due to the power they 
have—notably thespecies of the Euphauside —of emitting lightfrom various 
parts of their bodies; and it is a curious circumstance that it is those 
species which have been observed to have preeminently the power of 
becoming luminous that are most frequently found in the stomachs of 
herrings, namely, Nyctephanes and Boreophausia. Whether the property 
of emitting light which these Schizopods possess has anything to do with 
their being so commonly selected as food by the herring, cannot be easily 
answered, though it is probable that their luminosity may have some 
connection with it. 
The somewhat singular auditory organs observed in many of the 
Mysidz are very interesting. They are conspicuous owing to their 
glistening transparency ; they appear as clear circular vesicles near the 
base of each of the inner caudal lamelle, which are at this part suddenly 
enlarged to afford space for the vesicles. Viewed with a low power, each 
vesicle appears to be formed of concentric zones or laminz, which are 
alternately more and less clearly transparent; with a moderately high 
power, the auditory ossicle may be observed. The position of the 
auditory organs here referred to seems confined to the Myside. The 
Cumacez according to Claus do not possess auditory organs. 
The distribution of the Ostracoda, as might be expected from their 
frequenting the mud, sea-weed, and zoophytes at the bottom, is, like that 
of the Decapods, little influenced by the various seasons. The free- 
swimming Copepoda are decidedly different in this respect. During the 
later months of spring, and in summer and early autumn, they are at 
times captured in great abundance by the surface-net ; whereas during the 
colder months, comparatively few are to be met with, even though the net 
be sunk to a considerable depth. In April and May I have also found 
the larval or free-swimming forms of Salant exceedingly numerous— 
much more so than at any other season. If adult Balani be collected 
about this time, and left in sea-water for an hour or two, swarms of these 
larval forms may be observed swimming about. It is probable that 
during this time when the sea around our coasts is swarming with these 
very minute organisms, the herring, and possibly other fishes also, may 
make use of them as food, by drawing them into their mouths along with 
the water of respiration, and retaining them while the water passes tu 
through the opercula, as Dr Mobius suggested ; but there is no doubt that 
herring can, and do, discriminate between one form of food and another, and 
purposely capture the organisms on which they generally feed, whether 
Copepods, Amphipods, or Schizopods. 
The importance of this extensive class of organisms—perhaps the most 
extensive among the Invertebrata—is a sufficient reason, if only from a 
commercial point of view, for its being carefully and thoroughly studied. 
In the list here given, over 230 species of Crustacea are recorded 
as occurring in the Firth of Forth, including 41 species of Ostracoda, 42 
of Copepoda, and 13 Schizopods. 
In the list prepared by Leslie and Herdman, 99 species are enumerated ; 
and Dr Henderson in his paper added other 21 species, which, including a 
few doubtful forms, brought the total up to 120 species, The number of 
species in the present list, exclusive of the two additional groups, Ostra- 
coda and Copepoda, and leaving out doubtful forms, is about 150, which 
shows that the investigations carried out during the pst year under the 
directions of the Fishery Board have been fairly successful in adding to 
our knowledge of the distribution of this important class of organisms. 
