148 
PROFESSORS T. W. BRIDGE AKD A. C. HADDON 
but in neitiier instance does he give any precise or detailed account of the organ. Of 
the general accuracy of Day’s brief description there can be no doubt, inasmuch as 
Glyptosternum affords a further illustration of the type of rudimentary air-bladder to 
which we have already directed attention in our account of Akysis, Acrochordonichthys, 
and Bagarius, but as regards the extent to which the diminutive air-bladder is 
incapsuled by bone, his account does not accurately apply to G. platypogon, which is 
the particular species we have examined, and the one in which Cuvier and Valen- 
ciennes denied its existence. 
Of the various abnormal genera that so far have come under our notice, Glypto- 
ste7'num most nearly resembles Bagarius in the structure of the air-bladder, and the 
condition of the modified anterior vertebrm. The body of the first vertebra is, how- 
ever, somewhat better developed, but, although clearly visible on the ventral surface, 
it is almost completely excluded from forming any portion of the floor of the neural 
canal by the apposition of the dorsal edge of the basioccipital and the corresponding 
margin of the complex centrum (fig. 55, v.'). The first, the complex, and the fifth 
vertebrae (v.^, c.c., and v}) are rigidl}'' united to one another and with the skull, but the 
union is entirely due to the character of the persistent sutural articulation of the 
different cranial or vertebral elements and not to their anchylosis, or to the growth of 
continuous superficial ossifications. The intervertebral sutures between the centra 
are clearly seen on the ventral and lateral surfaces, as also is the suture between the 
neural arches of the complex and fifth vertebrae on the lateral aspect. The body of 
the complex vertebra (c.c.) is much larger than that of the fifth vertebra {v}), and in 
each case the anterior and posterior concavities are about equal in depth. The sixth 
vertebra (v.®) is quite free, being movably articulated with the foregoing. 
The confluent spines of the third and forth vertebrae together form a thin, triangular 
lamina of bone, with sloping anterior and posterior margins, and a pointed distal 
extremity (fig. 5G, u-s} and n.s.'^). The anterior margin and distal end of the lamina 
are suturally united to a thin vertical plate of bone which grows downwards from the 
longl backwardly directed supraoccipital spine (so.'). The spine of the fifth vertebra 
(ii.s.^) is unusually stout, and, moreover, is cleft distally into two processes, which are 
flattened on their opposed faces, and bent slightly outwards for the support of the 
anterior interspinous bones of the dorsal fin. 
Each of the transverse processes of the fourth vertebra is greatly expanded, and 
also tilted slightly upwards from its root outwards (figs. 55 and 5G, tp.^). The root 
of the process is thick and flat, but for the distal two-thirds of its extent the process 
is comparatively thin, with its anterior and posterior margins curved downwards, 
whereby it becomes modified to form the roof and side walls of a transversely-disposed 
bony semicylinder, the cavity of which is open distally as well as proximally in the 
dry skeleton. The anterior margin not only curves downwards, but also a little 
backwards ; the posterior margin is also decurved, but to a somewhat less extent than 
the former, and, with its distal extremity, which is prolonged outwards into a slender 
