26 THE ROYAL SOCIETY OF CANADA 
indistinctly indicated. Clearer and darker materials do occur, but they 
are arranged in areas rather than zones, the darker material tending to 
occupy the central portion of the ossicle and the clearer the more 
peripheral portions. Ossicles from different fish show great diversity 
in the relative amounts and distribution of the two materials. In 
Text-figures 6 and 7 are shown the sagittæ of two fish, in one of which, 
Text-figure 6, the dark material is confined to the area of the central 

Text-fig. 6, 8.—Three sagittæ from Humpback Salmon. The shaded area indicates 
the extent of the darker region in each and in Fig. 6, the outlines of 
the groove for the nerve are indicated. 
nucleus and the immediately adjoining region, the rest of the ossicle 
being composed of a clear almost transparent material in which no zones 
representing summer and winter growth can be recognized. In the 
ossicle shown in Text-figure 7, the dark area, represented as in the 
former figure by the shading, is much more extensive, occupying almost 
the lower two-thirds of the ossicle, while the clear area is confined to 
the upper and posterior margins. In another ossicle (Text-fig. 8) the 
dark material again forms about two-thirds of the structure, but is 
quite differently arranged, the clear material being confined to the 
upper border alone. In this case indications of the central nucleus and 
of what is probably the winter check during the life in the sea are also 
imperfectly indicated. 
