Jaws and Teeth

jaw, lower, upper, tooth and plate

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Inspection of figures 12 and 13, plate iv, shows that the teeth are set in alveoli or sockets in each ramus of the mandible and the pre maxillary, and in each palatine. These teeth are polyphydont—that is, they are replaced by new teeth as soon as they are worn down, broken off, or become loosened in their sockets. In some socketed teeth the succession is vertical, i. e., the new tooth is formed in the same socket as the old one and grows out at the same aperture. This is by virtue of the fact that the base of the old tooth is absorbed and the new tooth thus comes to lie below it and to take its place. In other fishes the new tooth succeeds its predecessor, growing side by side with it or its stump.

In the great barracuda the teeth are set in sockets, out of which they grow by multiplication of cells at their pulpy bases. Room for the new teeth is often made by the old teeth being broken off, where upon the root is resorbed and a new tooth erupts alongside the first to take its place. This state of things can be seen in the photographs of the skull of the specimen from Miami, as shown in figures 12 and 13, plate iv. In the figure of the lower jaw, the fang at the terminus of the left ramus has been broken off and already one sees the chink through which the new tooth will emerge. In figure 12, of the upper jaw, we have a similar state of affairs. The left front fang has been broken off, the one next to it has become loose in its socket and in the space between the two is seen the hole out of which the new tooth will come.

Closer inspection of figures 12 and 13, plate iv, will show some two dozen similar cases among the premaxillary, mandibular, and pala tine teeth. All stages can be made out from the recently broken-off stumps to the half-grown replacing tooth. This is the reason for the variable number of great fangs at the apex of the upper jaw. Some of these in the cleaned head, it should be noted, were so loose in their sockets that they had to be glued in to prevent their being lost. A similar state of affairs is revealed by a close examination of the jaws of the three dried heads. The study of the succession of teeth in this fish would be of both interest and value. It would, however, have to be undertaken where there was an abundance of fresh material.

Before taking up the literature of this phase of the subject it is well to emphasize the fact that all my specimens and their figures show but one fang at the symphysis of the lower jaw. For this see the figures of the dried heads on plate III; and figure 13, plate Iv, showing the teeth of the fresh specimen from Miami. These single fangs are always inclined toward the median line, the ones situated on the right side are inclined towards the left, and vice versa. Inspec tion of the largest dried head and of the fresh specimen, however, shows that the left tooth has only recently been broken off; while in dried head No. in, a new fang is just ready to erupt on the right side.

Apparently two teeth belong at the apex of the lower jaw, but only one seems to be present at any given time. This point will be taken up again after the literature of the subject has been reviewed.

The earliest writer whom I have found to give any accurate descrip tion of the jaws and teeth of Sphyrcena is Rondelet (1558).* Writing of the European form, the spet, he says: " The lower jaw is longer than the upper, ends in a point, and receives the upper jaw into itself. . . . It has strong pointed teeth curved inwards like those of the Murtena. On the upper jaw there are four, and on the palate are two rows of teeth. At the center (apex) of the lower jaw there is one tooth greater than all the others, which enters into a cavity in the center of the upper jaw made on purpose to receive it." Even clearer and more explicit is the Roman physician, Salviani, whose folio work on fishes appeared in the same year as that of the Latin edition of his contemporary. He writes: "The upper jaw is obtuse and shorter, the lower acute and longer. As a result, the point of the wedge-shaped beak is constituted only of the extreme part of the lower jaw; and into the lower and longer maxilla, the shorter upper jaw fits when the mouth is closed. Each jaw is fortified with teeth, the upper with larger ones, the lower with smaller; and in the middle of the anterior part of this lower jaw, indeed in the very hiatus of the mouth, there stands out one tooth the longest and sharpest of all. This, when the mouth is closed, is so received into a foramen in the anterior and membranous part of the upper jaw, that this projects a little on the These descriptions, though made from the Mediterranean species, are more accurate for our fish than is Sloane's, even though his was written from the West Indian form found at Jamaica. Sloane says (1707), of a barracuda 15 inches long and hence immature: "The under jaw had two Rowes of small Teeth, and one long one at the End in the Middle, the upper had one Row of small teeth on the outside and another within of long ones." Catesby's description (1754) is also very imperfect. For his fish see figure 16, plate v. He simply says of Bahama specimens: "The upper jaw is armed with four large teeth, placed at [opposite to] the fore part of the under jaw; next the head are placed ten smaller teeth, being five on each side; and in the fore part of [the lower jaw] . . . grows one single large tooth." Patrick Browne (1756) found two large canines at the apex of the lower jaw, which he notes was the longer. The mouth is described as very large, the jaws especially so. These are filled with many oblong lanceolate teeth, "whereof the two foremost [on the lower jaw] pierce through so many sockets formed in the tips of the upper jaw, while others lodge on either side of the opposite teeth." He seems to be the first to note the presence of teeth on the tongue and of the two lower fangs.

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