. Bulletin of the Bureau of Fisheries. Fisheries; Fish culture. Fig. 13.âHead of Maine â whitefish (Coregonus labradoricus). RANGELEY LAKES, MAINE: FISHES, ANGLING, AND FISH CULTURE. 521 Whether or not those of the Michigan fish are constant can be told only by an examina- tion of a larger number of specimens. In certain proportional measurements the Umba- gog fish approaches the Maine fish, intergrading or interlinking the Michigan with the Maine form, suggesting that the change to the conditions of environment found in Maine is correspondingly modifying the fish and thus indicating that the
. Bulletin of the Bureau of Fisheries. Fisheries; Fish culture. Fig. 13.âHead of Maine â whitefish (Coregonus labradoricus). RANGELEY LAKES, MAINE: FISHES, ANGLING, AND FISH CULTURE. 521 Whether or not those of the Michigan fish are constant can be told only by an examina- tion of a larger number of specimens. In certain proportional measurements the Umba- gog fish approaches the Maine fish, intergrading or interlinking the Michigan with the Maine form, suggesting that the change to the conditions of environment found in Maine is correspondingly modifying the fish and thus indicating that the differences between the Michigan and Maine fish may be merely ontogenetic. In the dim light of our present knowledge, however, it seems best to continue to regard the native Maine form as a distinct species, although the geo- graphical limits of either form are unknown. The most conspicuous and about the only distinct differences shown by the specimens examined are in the shape of the head and form of some of the head bones. In the Umbagog fish, as well as those of the Michigan waters that have been ex- amined, the supraoccipital and parie- tal bones slope from the nape to the f rontals, forming a somewhat concave profile, figure 12. In the Maine fish the profile is always straight and continuous with the line of the nape, figure 13. In the Umbagog fish the opercular bones are proportionally deeper and the supplemen- tary maxillary proportionally longer and narrower than in the Maine fish, and the lower jaw of the Umbagog fish is slightly shorter than in the Maine fish. The following comparison of averages of proportional measurements of the Umba- gog, Maine, and Michigan fish, respectively, in many instances shows the previously mentioned intergradation: Head of Umbagog fish longer than that of the Maine fish and slightly longer than that of the Michigan form. Maxillary, longer than Maine and Michigan, the latter two essentially alike. Mandible, shorter than Maine, about the
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