﻿250 DK. E. H. TEAQUAIR ON FOSSIL [May 1910, 



' It [the scale] measures a quarter of an inch in height by the same in 

 breadth ; its shape is rhomboiclal, having an extensive anterior covered area 

 and a strong articular spine projecting from the upper margin. The free 

 surface is brilliantly ganoid, and marked with furrows separating feeble ridges 

 which pass rather obliquely downwards and backwards across the scale, and 

 terminate in eight sharp denticulations of the hinder margin.' 1 



Fig. 2 (PI. XIX) shows one of the scales collected by Messrs. 

 Andrew & Bailey, magnified 4 diameters. It resembles in all essen- 

 tial particulars the one described above, though the articular spine 

 is concealed in the matrix. The covered area is only slightly pro- 

 duced upwards at the anterior superior angle ; the exposed area is 

 brilliantly ganoid, and marked by furrows into eight feeble oblique 

 ridges which are most conspicuous posteriorly, where they pass 

 into sharp and prominent denticulations of that margin : the feeble 

 ridges being again more prominent, though flattened, along the 

 anterior margin of the ganoid area. A few punctures are also seen 

 on the ganoid surface. 



In fig. 3 the ornament is of the same general character, but 

 more distinctly marked, and extends all over the surface. Here 

 the articular spine, short and pointed, is well shown. 



Fig. 4 shows a scale of larger size, which evidently had belonged 

 to a fish of superior dimensions ; its greater obliquity would like- 

 wise indicate a more ventral position. Here the whole free surface 

 is covered by oblique ridges, sharp and strongly marked, slightly 

 curved with the convexity downwards and occasionally bifurcating. 

 Punctures are also present, and the posterior border is marked by 

 several very pronounced sharp denticulations. 



If the ridges and furrows are more pronounced on some scales, so 

 in others the punctures are more conspicuous, as, for instance, in the 

 portion of a large scale represented in fig. 5, magnified 3 diameters. 



If it be now accepted that the scales in question belong to the 

 species ' africanusf the question of their genus next comes before 

 us. For Acrolepis the scales are rather too thin, the covered area 

 proportionally not broad enough, and its anterior-superior angle 

 not sufficiently produced, while the denticulated border is also 

 against this reference. For, although Dr. A. S. Woodward has 

 described and figured as Acrolepis (?) digitata some scales from the 

 Karroo Formation with denticulated hinder margin, he expressly 

 states that the name is only provisional. He rightly remarks, 

 however, that this character is usually only of specific value, so 

 that it does not absolutely forbid the inclusion in Acrolepis of a 

 posteriorly denticulated scale. 2 



But I have already remarked on the resemblance of these scales 

 to those of Colobodus, and it may now be asked whether there is 

 any further evidence that their true position may be in this genus. 



Among the specimens sent by Messrs. Andrew & Bailey is a 

 dentigerous bone, which is represented twice the natural size in fig. 6. 

 This bone seems to have consisted of a broad flattened portion which 



1 See Drummond's ' Tropical Africa ' London, 1888, p. 194. 



2 ' Catal. Foss. Fishes Brit. Mus.' pt. ii (1891) pp. 508-509. 



