Identifier: zologytextbook00cock (
find matches)Title:
Zöology; a textbook for colleges and universitiesYear:
1920 (
1920s)Authors:
Cockerell, Theodore D. A. (Theodore Dru Alison), 1866-1948Subjects:
ZoologyPublisher:
Yonkers-on-Hudson, N. Y., World book companyContributing Library:
MBLWHOI LibraryDigitizing Sponsor:
MBLWHOI LibraryView Book Page:
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view book online to see this illustration in context in a browseable online version of this book.Text Appearing Before Image:csnus) are modified into immense tusks,which are used in digging for food and in fighting.Although the animals are so large, they feed mainly onbivalve mollusks which they find in the mud and sandof northern shores. (d) Rodentia, Rodents, or gnawing animals, bestknown by their peculiar teeth. The canineteeth are absent, while the incisors grow frompersistent pulps, grinding against one another.When, as occasionally happens, an upper in-cisor is knocked out, the lower one opposed toit continues to grow in a circle, eventuallyentering the brain and killing the animal. Thesurfaces of the grinding teeth are more or lessflattened, not conical as in carnivores and in-sectivores. The enamel pattern is often elabo-rate. Rodents are the dominant and diversifiedmammals, in this respect corresponding to thePasseriformes among the birds. They includethe squirrels, chipmunks, woodchucks, beavers,gophers, mice, rats, porcupines, guinea pigs,and many lesser-known forms. The guinea pigs MAMMALS 405 rText Appearing After Image:Photograph by E. R. Warren, Mammals of ColoradoFIG. iyg. Pika (Ochotona saxatilis); Irwin, Gunnison County, Colorado. Thepikas, often called conies, are found among rocks in the mountains of the northernhemisphere from Eastern Europe to Western America. Their cheerful cries maybe heard in the summer far above timber line. These animals constitute a verydistinct family, related to the rabbits, but with short ears and no tail.Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.