CARBONIFEROUS FISH-FAUNA, 
impressed on the original of fig. 8, the hinder sector of the inner 
face is shown to have been covered by fine pittings and tubercles, 
which are apparently more numerous than in the known scales of 
Strepsodus. 'The slime-canal of the lateral line must have been 
large, as shown by its mould (fig. 10). 
Jaws and Teeth.—The collection includes only two portions of 
mandible and a few imperfect teeth, which are noteworthy as 
being large compared with the scales just described. The height 
of the largest laniary tooth is 0.05 m., while the maximum dia- 
meter of the largest scale is 0.045 m. The remains are suffi- 
ciently well preserved to exhibit the characteristic form and 
structure of a Rhizodont mandible, and the larger of the two 
specimens is represented from the outer aspect in Pl. VIIL., fig. 1. 
The dentary bone is a thin lamina with traces of an external tuber- 
cular ornament. Its oral margin bears a single regular series 
of small conical teeth, which are very slightly compressed antero- 
posteriorly and are scarcely incurved at the apex. These teeth 
are typically Rhizodont, with folded base and small pulp-cavity. 
Evidence of the shuttle-shaped bones bearing the laniary teeth is 
seen in both specimens; and one of these elements bearing two 
teeth (namely, one laniary with the successor by its side) is 
imperfectly represented near the front end of Pl. VIII, fig. 1. 
Like the smaller teeth the laniaries are not sigmoidally bent, but 
only incurved at the apex. They are rather stout, and when 
viewed in longitudinal section (figs. la, 2, 3) they exhibit the 
usual pulp-cavity with simple foldings of the wall at the base. 
Transverse thin sections of the teeth, when magnified, show clearly 
the simple character of the basal folds (fig. 4) and the absence of 
all folding in the upper part where the pulp-cavity still persists 
(fig. 4c). The ordinary thin vertical splenial lamina occurs on 
the inner face of the mandible. 
Jugular Plates——There are several remains of the character- 
istic paired jugular plates of a large Crossopterygian fish, and the 
two best specimens are shown in Pl. VII, figs. 2, 3, They also 
probably belong to Strepsodus decipiens, since it is the only large 
Crossopterygian identifiable in the collection from Mansfield. 
The original of Pl. VII, fig. 2, is an impression of the inner face 
[18] 
