Plagiostomata of the Pacific. Pt. I. Fam. Heterodontidae / by N. de Miklouho-Maclay and William Macleay.
- Nicholas Miklouho-Maclay
- Date:
- [1878]
Licence: Public Domain Mark
Credit: Plagiostomata of the Pacific. Pt. I. Fam. Heterodontidae / by N. de Miklouho-Maclay and William Macleay. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![As in H. Phillipi, so in H. gcileatus, the general form of the anterior part of the tooth-bearing surface is somewhat broader in the lower jaw than the same section of the upper, and somewhat quadrangular in shape. Figs. 30 and 31 give a pretty good representation of the form of the teeth. The anterior teeth are tri-cuspidate, the middle cusp being the most prominent, as a result of which, the front teeth appear high and narrow. In the antero-lateral teeth, the middle cusp is proportionally less elevated than the others ; further back, most notably in the reserve teeth (dents tfattente) of the medio-lateral rows, a principal cusp is no longer to be recognised, the front pointed cusps being represented by a sharp sinuous ridge, provided with an obscurely dentate upper contour. This ridge is particularly well-developed in the upper jaw, while in the lower it remains always sinuous and thin. The transverse section of one of the large (elongated) teeth of the upper jaw (which, as already mentioned, I was, from lack of material, unable to make) would have a pyramidal form with one side slightly convex, and the other concave, i.e., the outer surface of the elongated (lateral) teeth is concave; the inner convex. The complete jaws in the Australian Museum afford me an opportunity of describing also the numerical characters of the teeth of H. galeatus. In the upper jaw, I have counted altogether 30 vertical rows of teeth; the number of teeth in the antero-median rows proved to be 11 (of which, however, the 10th and 11th were worn down) ; the number of the lateral elongated teeth in the penulti- mate vertical row was 9. In the lower jaw I found altogether 26 vertical rows ; in the middle rows I counted 15 teeth* ** ; there were 10*# in the vertical row, containing the largest teeth (the third row, counting from behind.) * The three posterior reserve-teeth of the middle row were displaced, so that possibly this number (15) may not be quite correct. ** In this jaw, I have also remarked the two following’ peculiarities. The postero- lateral rows are unsymmetrical; i.e., two teeth on the one side correspond to one on the other. If we examine the teeth of these lateral rows, one after another, from without inwards, the three first elongated teeth prove to bo normal, with a straight longitudinal ridge; on the fourth and fifth reserve teeth, wo see a slight curving inwards of the ridge : on the sixth, the ridge is interrupted, and the baso of tho tooth is also somewhat incurved at the corresponding place. The places of tho following reserve-teeth are each occupied by two smaller teeth. Whilo we notice this division in the posterior rows, wo find, on the other hand, in one of the antero-lateral rows, a coalescence of two tricuspidatcd teeth. I will not omit in the contemplated “ Monographic Sketch of the Dentition of Heterodontus,” referred to above, to give illustrations and a more thorough description of theso pecu- liarities. [21]](https://iiif.wellcomecollection.org/image/b22367913_0023.jp2/full/800%2C/0/default.jpg)
