. Animal Life and the World of Nature; A magazine of Natural History. Animal Dentition 289. Fig. 5. Palatal Den- tition of an otliei Pycnodont Fish (Gyrodus). corresponding portion of the lower jaw, this dental plate becoming- very large in the second of the two genera, where it is divided into two halves by a median cleft. The most remarkable feature about these teeth is, however, their structure, since they consist of a vast number of very thin plates superimposed upon one another somewhat obliquely, so that their edges are exposed upon the grinding surfaces. In these teeth the uppermost pla
. Animal Life and the World of Nature; A magazine of Natural History. Animal Dentition 289. Fig. 5. Palatal Den- tition of an otliei Pycnodont Fish (Gyrodus). corresponding portion of the lower jaw, this dental plate becoming- very large in the second of the two genera, where it is divided into two halves by a median cleft. The most remarkable feature about these teeth is, however, their structure, since they consist of a vast number of very thin plates superimposed upon one another somewhat obliquely, so that their edges are exposed upon the grinding surfaces. In these teeth the uppermost plates are, of course, the oldest. Globe- fishes feed largely upon coral, the branches of which their dentition is admirably adapted to break off and crush. The allied genus Triodon is intermediate between the other two so far as its dentition is con- cerned, the upper jaw-tooth being divided, while the lower one is single. The huge Sun-Fishes, which are nearly allied to the globe-fishes and have a dentition of somewhat similar type, claim special notice on account of the circumstance that teeth are also developed on the bony arches by which the gills are supported, as shown in Fig. 7. In this connection it may be mentioned that up to a few years ago the largest known sun-fish was a specimen in the British Museum, taken off the Dorsetshire coast in 1846. Its length is 7J feet. This specimen is, however, largely exceeded in size by one captured off Kedondo, California, which is reported to have measured 8 feet 2 inches in length and to have weighed nearly 1,800 lbs. Distant allies of the globe-fishes, the File-Fishes (Batistes) of the tropical seas have an altogether distinctive and peculiar type of dentition, in which the large teeth are limited to the jaws and the pharyngeal bones. In the upper jaw (Fig. 8) there are seven pairs of teeth arranged in two rows—four in the front and three in the hind row. The lower jaw carries only four pairs, corre- sponding to those of the front
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