274 Bashford Dean Memorial Volume 



27 rows below. In the angles of the jaws, on both lower right and left and in the upper 

 left, we find the last row of teeth imperfectly developed. On the left side above and below, 

 the last row has only the central cusps developed, while in the right lower side the last 

 row has the central and outer cusps only. In fish No. II (a 1485'mm. female) we found 

 11 and 8 rows on the sides of the upper jaw, and beyond the last row rudimentary struc 

 tures which our best efforts were unable to differentiate as either teeth or shagreen denti' 

 cles. The lower jaw has only 12 rows on the right and 11 on the left, with a central row 

 of teeth at the symphysis. Our fish No. Ill (1550 mm.) shows nothing unusual save a 

 reversal of the count — the right side having 13 rows above and 12 below, the left 12 above 

 and 13 below. There is also in the center of the lower jaw the usual single row of teeth. 



The Columbia University specimen (a head only) has a remarkable abnormality, the 

 exact counterpart of which has not been found in any other fish. The lower jaw has 11 

 rows on the right, and 12 on the left, with the usual median row. The upper jaw has 13 on 

 each side plus 2 rows of small teeth almost in the center of the symphysis. This double 

 row, as may be seen in Plate III, figure 10, is slightly displaced toward the right — the 

 distance between the right-hand teeth of the right-hand central row and their neighbors 

 being 5 mm., while on the left the distance is 8 mm. The teeth of the double row are very 

 small, measuring (height or length of central cusp) 2.25 mm. in each row, whereas the 

 perfect central cusps of the neighboring normal teeth measure 4.5 mm. in length. These 

 teeth are shown enlarged about two times in Figure 13, plate IV. From this one may judge 

 that an extra tooth anlage, which might have produced a single central row of normal- 

 si2;ed teeth, has produced an abnormal double row of teeth, each tooth half the normal 

 si2;e. Furthermore this double row of small teeth corresponds plainly to the abnormality 

 described by Collett, though the double row of teeth referred to by him constitutes the 

 second side-row of the left lower jaw, while ours is found at the center of the upper jaw. 

 He unfortunately gives neither figure nor measurements, merely saying "somewhat smaller 

 than normal teeth." 



In Doctor White's specimen, elsewhere referred to, we find an abnormality much 

 like that just described. In the upper jaw of this female 1398-mm. specimen, about half 

 way from the exact center of the symphysis to the first right lateral row of normal teeth, 

 there is a single row of teeth half the normal size for this jaw — i.e., the central cusps are 

 2 mm. long instead of 4. There are 6 teeth in this pygmy row and 5-6 in the rows of 

 normal teeth — some rows have the outer tooth broken off. It would seem that the cause 

 of this abnormality is very similar to that which produced the teratological tooth-rows 

 just described. It is interesting to note that these variations in both fish are found in the 

 same position, i.e., to the right of the center of the upper jaw. In Doctor White's speci- 

 men (Figure 14, plate IV), the abnormal tooth anlage, which in the other fish produced 

 two rows of half-sized teeth, equivalent to a full-sized single row, has here brought forth a 

 single row of half-sized teeth. The other row has been suppressed. 



In one of our (American Museum) specimens, another interesting abnormality is 

 found. As may be seen in Figure 15, plate V, there is, just anterior to the hinder edge of 



