116 Gunther—Plinthophorus robustus. 
bre nearest to the head, perhaps six or seven in number, having been 
lost ; the remaining portion is composed of fifty well ossified and 
solid vertebre ; in comparison with their circumference, they are of 
moderate length, with the articular portion considerably swollen, 
and with the central part much contracted; their surface is rough, 
deeply furrowed by longitudinal grooves. ‘The following are the 
measurements of some of the vertebre. As regards the number with 
which the several vertebrae are marked, I must remark that the first 
seven are supposed to have been lost, so that the entire column would 
be formed by 57 vertebrae :— 
Length of the entire vertebral column . 16% inches. 
A ninth vertebra é : 32 lines 
Width of its articular surface P : 92 3 
Length of the twenty-eighth vertebra . 4 Bs 
Width of its articular surface ; eon Tara 
CO MULe nas : cS Mapa 
Length of the forty-fourth porioers oa) Nes 
Width of its articular surface A a 
The neural and hemal spines are of moderate length ‘and strength, 
and those of the last six vertebrae, which are much shor tened, : are 
close together, imbricate, forming the base for the caudal fin, The 
ribs are simple and slender, not stronger than the neural spines, and 
appear to be continued to the thirty-fourth vertebra. 
The dorsal fin is composed of sixteen rays, of which the anterior 
are rather strong and long, the posterior gradually decreasing in 
strength and lenath, The first ray is the strongest : : a portion of it, 
more than two inches long, is preserved, but it must have been at 
least three and a half inches long when intact; its interneural spine 
corresponds to the neural of the nineteenth vertebra. The rays of 
the anal fin are in an imperfect state ; their number appears to have 
been eleven. This fin resembles the dorsal in general form, the an- 
terior rays being much longer than the posterior; its interhzmals 
correspond to the haemals of from the thirty-eighth to the forty-fifth 
vertebra. The caudal jin is forked, the lobes being of moderate 
lene th. 
The pectoral is inserted quite below on the side of the trunk, and 
composed of twelve rays, the first of which is very short, rudimen- 
tary ; the second the longest, twenty-nine lines long. The distance 
between the root of this fin and that of the ventral is 64 inches. The 
ventral fin is composed of ten or eleven rays, and has a broad base, 
which les below the twenty-seventh vertebra, or immediately behind 
the last dorsal rays; its longest rays were at least nineteen lines 
long. The pubie bones are flat, elongate-triangular, as long as the 
ventral fin, leaving a narrow, free space between their symphysis 
and anterior extremity. 
No traces of scales are visible, but there are the remains of series 
of imbricate osseous scutes, a great part of which still occupy their 
natural position. One series runs along each side of the uppermost 
part of the back, from the nuchal region, along the base of the dorsal 
fin, towards the caudal fin; the anterior portion of this series, to the 
middle of the dorsal fin, is well preserved, whilst only single scutes of 
