cordone almo (1 risultati)

Quarto, paperbound (stiff, stapled tan and green wrappers), 12 pp. Good, with light soiling to wrappers. From Introduction: Listed below are the living marine mammals of the world: the sea otter, pinnipeds, sirenians, and cetaceans. Certain animals descended from marine ancestors but now living in inland waters are included. (The Caspian nad Baikal seals may have been confined to inland waters since the origin of the Phocidae from their presumed terrestrial ancestors (McLaren, 1960). A bibliography of sources is given on page 9. Any attempt to classify the marine mammals is beset with special difficulties arising from the fact that they are poorly known. Some of them live on the high seas, others on remote oceanic islands and among polar ice fields. Some of the sirenians and smaller cetaceans live in tropical waters seldom visited by naturalists. The carcases of marine mammals are large-bodied, greasy, and bloody, and often putrify before they are brought tot he attention of biologists. In general, they are difficult and expensive to collect and to preserve for study. As a result, many kinds are known to science only from bones and fragments. For example, in 1952, Yamada collected a strange 8-foot porpoise at Taiji, Japan. Upon dissection, it proved to be Feresa attenduata, known up to then from two skulls which had lain for a century in the British Museum. Only 6 years ago, a new genus of dolphin (Lagenodelphis) was described by Fraser (1956) on the basis of a skeleton recovered from a sea beach at Borneo; and in 1937, a whale which proved to represent a remarkable new genus (Tasmacetus) of beaked whale washed ashore on New Zealand. In 1958, in the collections of the U. S. National Museum and the British Museum, there was apparently only one skull - a broken one - of the ribbon seal (Illiistrio-phoca fasciata), yet the population of this animal in Bering and Okhotsk Seas must surely be numbered in tens of thousands. Natural History, Marine Biology, Zoology, Marine Mammalogy, Biology, Cetology, Cetaceans, Whaleology, Dolphins xslic.