. The study of animal life. Zoology. CHAP. XV Backboneless Animals 239 The members of the last four classes usually breathe by means of air-tubes or tracheae, which penetrate into every part of the body, or in the case of spiders and scorpions, by " lung-books," which seem like concentrated and plaited tracheae. The King-crab (Limulus), which is very often ranked along with Arachnids, is aquatic, and breathes by peculiar "; (a) Crustacea.—Except the wood-lice, which live under bark and stones, the land-crabs which visit the sea only at the breeding. Fig. 45.—Naup
. The study of animal life. Zoology. CHAP. XV Backboneless Animals 239 The members of the last four classes usually breathe by means of air-tubes or tracheae, which penetrate into every part of the body, or in the case of spiders and scorpions, by " lung-books," which seem like concentrated and plaited tracheae. The King-crab (Limulus), which is very often ranked along with Arachnids, is aquatic, and breathes by peculiar "; (a) Crustacea.—Except the wood-lice, which live under bark and stones, the land-crabs which visit the sea only at the breeding. Fig. 45.—Nauplius of Sacculina. (From Fritz Muller.) time, and some shore-forms which live in great part above the tide- mark, the Crustaceans are aquatic animals, and usually breathe by gills. Each segment of the body usually bears a pair of append- ages, and each appendage is typically double. Among these ap- pendages much division of labour is often exhibited, some being sensory, others masticatory, others locomotor. In the higher forms the life-history is often long and circuitous, with a succession of larval stages. The lower Crustaceans are grouped together as Entomostraca. They are often small and simple in structure; the number of. 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 Thomson, J. Arthur (John Arthur), 1861-1933. New York, C. Scribner's sons [printed at the Edinburgh press]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1892
