. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 415. Fig. 418. Fig- 417. Figs. 411-418.— Devonian Lamellibranchs and Gasteropods: 411. Conocardium trigonale (after Logan). 412. Aviculopecten parilis (after Meek). 413. Ctenopistha antiqua (after Meek). 414. Lucina Ohioensis (after Meek). 415. Spirorbis omphalodes. enlarged. 416. Spirorbis Arkanen- Bis. 417. Orthonenia Newberryi (after Meek). 418. Bellerophon Xewberryi (after Meek). Goniatites, a coiled-chambered shell, which seems to be the beginning of the Ammonite family, are introduced first here. T
. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 415. Fig. 418. Fig- 417. Figs. 411-418.— Devonian Lamellibranchs and Gasteropods: 411. Conocardium trigonale (after Logan). 412. Aviculopecten parilis (after Meek). 413. Ctenopistha antiqua (after Meek). 414. Lucina Ohioensis (after Meek). 415. Spirorbis omphalodes. enlarged. 416. Spirorbis Arkanen- Bis. 417. Orthonenia Newberryi (after Meek). 418. Bellerophon Xewberryi (after Meek). Goniatites, a coiled-chambered shell, which seems to be the beginning of the Ammonite family, are introduced first here. This family, as already explained, is distinguished by the complexity of the junction of the septa and the shell (suture), and by the dorsal position of the siphuncle. In the Goniatites the sutures are not yet very complex. They are only zigzag. This is shown in the fig- ure. Crustacea.—The very characteris- tic Palaeozoic order Trilobites is still abundantly represented, although it has already passed its prime, and is diminishing in number and size of species. The Euryptends introduced in the Upper Silurian maintain their place through the Fig. 419. -Goniatites lamellosus (after Pictet).. 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 LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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