. Devonian fishes of Iowa. Fishes, Fossil; Paleontology; Paleontology. DEVONIAN FISHES OF IOWA 55 derived from the recent studies of Dr. Otto Jaekel, in Germany, and Professor William Patten, of Dartmouth College, in this country. Without entering at this point into the basis of classification, it may be remarked in passing that the different families of Os- tracophores are commonly arranged in four ordinal divisions, of which the Heterostraci are regarded as the most primitive. This order comprises the curious group of Pteraspidians, the struc- ture of whose hard shield is unique among verteb
. Devonian fishes of Iowa. Fishes, Fossil; Paleontology; Paleontology. DEVONIAN FISHES OF IOWA 55 derived from the recent studies of Dr. Otto Jaekel, in Germany, and Professor William Patten, of Dartmouth College, in this country. Without entering at this point into the basis of classification, it may be remarked in passing that the different families of Os- tracophores are commonly arranged in four ordinal divisions, of which the Heterostraci are regarded as the most primitive. This order comprises the curious group of Pteraspidians, the struc- ture of whose hard shield is unique among vertebrates, and also the remarkable forms included within the families of Coelolepida? and Psammosteida?. Especially noteworthy among Coelolepids are the genera Thelodus (Fig. 1) and Lanarkia (Fig. 2), known. 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 Eastman, Charles Rochester, 1868-1918; Iowa Geological Survey. Des Moines : Iowa Geological Survey
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