. The study of animal life. Zoology. 198 The Study of Animal Life part m to the complex, from the general to the special, we must be careful to notice that he did not say that the young mammal was once like a little fish, afterwards like a reptile, and so on; he compared the embryo mammal at one stage with the embryo fish, at another stage with the embryo reptile, which is a very different Fig. 38.—Embryos of fowl, a; dog, h \ man, c. (From Chambers's Encyclop.; after Haeckel.) Fritz Mijller, in his Facts for Darwin, illustrated the same idea in relation to Crustacea. When a young cra
. The study of animal life. Zoology. 198 The Study of Animal Life part m to the complex, from the general to the special, we must be careful to notice that he did not say that the young mammal was once like a little fish, afterwards like a reptile, and so on; he compared the embryo mammal at one stage with the embryo fish, at another stage with the embryo reptile, which is a very different Fig. 38.—Embryos of fowl, a; dog, h \ man, c. (From Chambers's Encyclop.; after Haeckel.) Fritz Mijller, in his Facts for Darwin, illustrated the same idea in relation to Crustacea. When a young cray- fish is hatched, it is practically a miniature adult. When a young lobster is hatched, it differs not a little from the adult, and is described as being at a Mysis stage,—Mysis being a prawn-like crustacean. It grows and moults and becomes a little lobster. When a crab is hatched, it is quite unlike the adult, it is liker one of the humblest Crustacea such as the common water-flea Cyclops, and is described as a Zoea. This Zoea grows and moults and becomes, not yet a crab but a prawn-like animal with ex- tended tail, a stage known as the Megalopa. This grows and moults, tucks in its tail, and becomes a young crab. And again, when the shrimp-like crustacean, known as Penceus, is hatched, it is simpler than any known crustacean, it is an unringed somewhat shield-shaped little creature with three pairs of appendages and a median eye. It is known as a Nauplius and resembles the larva of most of the simpler crustaceans. It grows and moults and becomes a Zoea, grows and moults and becomes a Mysis, grows and moults and becomes a 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
