286 . acrolepis molyxeuxi and [May 1903, 



longest, extending the greater part of the distance across the scale, 

 while the others gradually decrease in length to the lowermost, which 

 does not extend forward beyond the posterior half of the exposed 

 face. The triangular anterior area thus left free from ridges is 

 marked by a few delicate lines parallel with the inferior margin, 

 in fact coincident with the lines of growth. The dorsal and ventral 

 scales of the abdominal region (PI. XX, figs. 5 & 6), and apparently 

 most of the scales of the caudal region, are longer than deep, though 

 none are excessively elongated. They are as coarsely ornamented 

 and serrated as the principal flank-scales already described, but their 

 ridges are only from five to six in number, and their anterior 

 striated area is relatively less in extent. The scales of the upper 

 caudal lobe are of an elongate-lozenge- shape and almost or quite 

 smooth. No ridge-scales are observable, except those of the upper 

 caudal lobe, which are rather small, narrow, and smooth. 



The rays of the pectoral fins (PL XX, fig. 1, pet.) have a long, 

 unjoin ted, smooth basal portion. The pelvic fins seem to have had 

 a moderately extended base-line, and the space between the latter 

 and the anal fin is much less than the maximum depth of the trunk. 

 The rays of the caudal fin are delicate and very closely articulated 

 to the base, and the tail must have been forked. 



This fish from the Sengwe Coalfield is clearly a member of the 

 family Paleeoniscidse, and it belongs to that section in which the 

 mandibular suspensorium is very oblique. 1 Though the teeth and 

 dorsal fin are unknown, its general aspect leaves little doubt that it 

 may even be assigned to a still more definite position in the small 

 group of which Elonichthys and Acrolepis are typical representatives. 

 Detailed comparison, indeed, shows that it is easily distinguished 

 from all known genera of Palaeoniscidse except the two just men- 

 tioned : and it differs from Elonichthys at least in the very deep 

 overlap of the scales. In the latter respect, and in all observable 

 characters which may be regarded as of generic value, the newly- 

 discovered fish agrees with Acrolepis, and to this genus it may 

 accordingly be referred. It differs from the typical species of 

 Acrolepis in the serration or pectination of its scales ; but isolated 

 scales with posterior serrations, from the Karoo Formation of Cape 

 Colony, have already been referred to this genus with much proba- 

 bility of correctness. 2 The scales of the fish now described are 

 readily distinguished from the latter by their peculiar external 

 ornamentation ; and they are similarly distinguished from all known 

 species, even from those based by Dr. Traquair on scales from the 

 north-western bank of Lake Xyasa. 3 The fish from the Sengwe 

 Coalfield thus represents a new species, which may be named 

 Acrolepis Molyneuxi in honour of its discoverer. 



[For the Explanation of Plate XX, see p. 200.] 



1 A. S. Woodward, ' Catal. Foss. Fishes Brit. Mus.' pt. ii (1891 ) p. 428. 



2 Acrolepis (?) digitata, A. S. Woodward, op. cit. p. 508 & pi. xv, fig. 4. 



3 Acrolepis (!) ofricana and Acrolepis (?) Drummondi, R. H. Traquair 

 in Drummond's ' Tropical Africa ' (1888) pp. 193, 194. 



