CARBONIFEROUS FISH-FAUNA, 
Vertebral Axis . — One fragment of the abdominal region of a 
Dipnoan large enough to have belonged to the head just described, 
exhibits a few very stout, curved ribs like those of the typical 
Ctenodus and Sagenodus. These ribs are round in section, with 
the central cavity which is always observable in the fossilised 
state. Two portions of a corresponding type of caudal region 
occur, one being an obscure fragment represented in PI. VIII, 
fig. 12, the other a tolerably well-preserved extremity of tbe tail. 
These specimens demonstrate the absence of vertebral centra, and 
exhibit stout, mesially-constricted, neural and haemal arches and 
fin-supports, which are only superficially calcified. The tail is 
clearly diphycercal. 
Squamation . — The portion of abdominal region already men- 
tioned exhibits impressions of large, thin scales, resembling those 
of Ctenodus found in the English Coal Measures. 1 The charac- 
teristic shape, thinness, and flexibility of these scales are still 
better seen in another piece of limestone, which contains some 
fragments of them. They display the usual very fine, radiating 
structural lines, which are crossed by the coarser and more 
irregular concentric lines of growth, without any enamel or 
ornamentation. 
Subclass TELEOSTOMI. 
Order Crossopterygii. 
Eamily RHIZODONTIDtE. 
Genus Strepsodus, Young. 
[Quart. Journ. Geol. Soc., vol. xxii, 1866, p. 602.] 
Numerous remains of a large Rliizodont fish are contained in 
the collection, and among them it is easy to recognise the scales 
and teeth of a new species of Strepsodus. This genus has 
hitherto been found only in the Carboniferous of the northern 
hemisphere. 
1 Hancock and Atthey, Nat. Hist. Trans. Northumb. and Durham, vol. iv. (1872), p. 398, 
pi. xiii, fig. 3 ; p. 417, pi. xvi. 
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