. Zoology : for students and general readers . Zoology. DEOAPODA. 313 abdominal feet; the compound eyes are large and usually sessile, and the carapace is often armed with a long dorsal and frontal spine. Fig. 265 represents the Zoea, or larva of the common sliore crab {Cancer irrorutus Say). After sev-. Fig. 265.—Zoea of the commoii Crab. Cancer. Much enlarged.—After Smith. eral moults, the thoracic legs appear, the mouth-parts change from swimming - legs to appendages fitted for pre- paring the food to be swallowed and digested. This stage in the short-tailed Decapods or crabs, is called the
. Zoology : for students and general readers . Zoology. DEOAPODA. 313 abdominal feet; the compound eyes are large and usually sessile, and the carapace is often armed with a long dorsal and frontal spine. Fig. 265 represents the Zoea, or larva of the common sliore crab {Cancer irrorutus Say). After sev-. Fig. 265.—Zoea of the commoii Crab. Cancer. Much enlarged.—After Smith. eral moults, the thoracic legs appear, the mouth-parts change from swimming - legs to appendages fitted for pre- paring the food to be swallowed and digested. This stage in the short-tailed Decapods or crabs, is called the Mega- lops stage (Fig. 266); certain immature crabs having been mistaken for and described as mature Crustacea, under the name Megalops. After swimming about the surface in the Zoea and Megalops conditions, the body becomes more bulky, more concentrated headwards, and the crab descends to the bottom and hides under stones, etc. The development of the individual crab is, in a general sense, an epiitome of the development of the order. In the lowest Decapods, as in Cuma and Mysis, the form is some- what like an advanced Zoea, while the remarkable concentra- tion of the parts headwards, seen in the crabs, is a great. 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 Packard, A. S. (Alpheus Spring), 1839-1905. New York : Henry Holt
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1879
