. Zoology : for students and general readers . Zoology. 134 ZOOLOGY. leaf-like amhuLxcra, and the irregularly heart-shaped, often elongated, form of the shell, an anterior and posterior end being well defined. They for the most part live buried in the sand or sandy mud, not moving about so actively as the Desmonticha. Of the family Spatangidm the singular genus Pourta- lesia (Fig. 87, P. Jeffreysii Wyville-Thompson) deserves notice, the species of which are bottled-shaped, with a thin, transparent shell. The transition from such a form as this to the Holothurians is not a very extreme one. Thi
. Zoology : for students and general readers . Zoology. 134 ZOOLOGY. leaf-like amhuLxcra, and the irregularly heart-shaped, often elongated, form of the shell, an anterior and posterior end being well defined. They for the most part live buried in the sand or sandy mud, not moving about so actively as the Desmonticha. Of the family Spatangidm the singular genus Pourta- lesia (Fig. 87, P. Jeffreysii Wyville-Thompson) deserves notice, the species of which are bottled-shaped, with a thin, transparent shell. The transition from such a form as this to the Holothurians is not a very extreme one. This genus, A. Agassiz states, is the living representative of In- fulaster of the Cretaceous period. P. miranda A. Agassiz was dredged in the Florida fetraits, in about three hundred. Fig. S7.—Fourtalesia J^reysii, slightly enlarged.—After WyvUle-Tliompson. and fifty fathoms, and by British naturalists in the Shet- land Channel. P. Jeffreysii was dredged in six hundred and forty fathoms, near the Shetland Islands. Spatangus is distinctly heart-shaped, as is Hemiaster. An interesting deep-sea or abyssal form not uncommon in deep soft mud, at the depth of one hundred fathoms, oS the coast of Maine and Massachusetts, and extending from Flor- ida around to Norway, is Schizaster fragilis Agassiz. Echinoderms range to a great depth in the ocean, and are largely characteristic of the abyssal fauna of the globe. In space they are widely distributed, there beiug but two Echinid faunae on the eastern coast of the United States, one arctic, the other tropical. While a large number of species characterize the arctic or circumpolar regions, the. 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
