of the Fishery Board for Scotland. 16 
authors at different times maintaining that they are specifically 
the same, a circumstance attributed to only a few specimens having 
been examined, and the specific characters as published ambiguous. 
By a study of the distinguishing characters and numerous measure- 
ments, Dr. Williamson shows that these two species are distinct, 
and a key is given incorporating the results of the previous and 
the present researches, by which the six species may be separated. 
The same naturalist supplies a paper, with two plates of drawings, 
on hermaphroditism in the cod, a condition which is normal in 
certain fishes, as the Gilthead (Chrysophrys auratus), and occurs 
occasionally in others. 
THE OTOLITHS OR EARSTONES OF FISHES. 
In this Report will be found a long and elaborate paper by Dr. 
Thomas Scott on the otoliths or earstones of teleostean or bony 
fishes, which is illustrated by five plates containing figures of the 
otoliths described, belonging to about seventy species. The 
otoliths of different fishes vary remarkably in shape and size, 
and Dr. Scott shows how these differences may be used as a means 
for the identification of the various species should other data not be 
available. It is thus sometimes possible, as the author has shown 
in previous papers, to tell upon what fishes a particular fish or ceta- 
cean may have been feeding, by the presence of the earstones alone. 
The otoliths consist almost entirely of calcareous matter, only a trace ~ 
of organic tissue being present. The structure shows that the limy 
matter is deposited in concentric layers, the density of each layer 
being slightly greater or less than the one immediately preceding 
it. In flat fishes, the earstones form round or oval discs, so thin 
that the alternating concentric layers are easily made out. The 
number of such layers, or growth-lines, appears to correspond more 
or less closely with the age of the fish, but Dr. Scott is of opinion 
from his researches that it is doubtful if the evidence of age 
obtained in this way can be safely relied on. 
The same naturalist also contributes a brief paper on new and 
rare copepoda from the Scottish seas, illustrated by a plate of 
drawings. Most of the species were obtained in the Firth of Forth 
and the Moray Firth. 
THE SPAWNING AND FECUNDITY OF THE PLAICE. 
An experiment was made on this subject by Dr. Fulton, by 
keeping adult plaice about to spawn in tanks and collecting all the 
eggs that appeared in the overflow daily, or twice daily. By this 
means the number of eggs spawned by each of the two females 
experimented with was determined, as well as the duration of the 
spawning and the quantity of eggs that appeared from day to day. 
One of the females spawned steadily, and almost daily for a period 
of 36 days, the quantity shed at any time being small; the 
spawning of the other extended over 41 days, but eggs were 
spawned on only 16 days during the period, large quantities of 
eggs being shed on each occasion, as many as 49,000. The first 
