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PROFESSORS T. W. BRIDGE AND A. C. HADDON 
Cryptoptems micropus. 
We examined two badly preserved examples of C. micropus and C. hexapterus, 
but their condition was such that our results are necessarily imperfect, except in so 
far as the skeletal modifications were involved. Enough, however, could be made 
out to justify the conclusion that in both species the air-bladder was in an incipient 
stage of degeneration. 
In C. micropus the body of the first vertebra is a mere flattened scale, and the 
complex centrum is but a trifle longer than the centrum of the fifth vertebra. Both 
the complex centrum and the basioccipital are provided with strong accessory 
articular processes on their ventral surfaces, A continuous deposit of superficial 
bone thickens the lateral surfaces of the centra of the complex and fifth vertebrm, 
which, otherwise, are suturally distinct from each other. There is a deej) median 
aortic groove. 
Each of the transverse processes of the fourth vertebra is partially cleft into 
slightly divergent anterior and posterior divisions. The anterior process has a 
strong ventral curvature, and a deflected anterior margin, but thins away to a 
somewhat pointed distal extremity. About tbe middle of its dorsal surface a strong 
process grows upwards, and is provided with an outwardly-directed facet for 
articulation with the post-temporal. The posterior division is directed horizontally 
outwards and a little backwards, and is also flattened in such a way that its surfaces 
look obliquely forwards towards the deflected margin of the anterior division, and 
backwards respectively. The comparatively slender transverse process of the fifth 
vertebra is partially confluent with the root of the preceding process, but for the 
greater part of its extent is directed outwards, parallel and slightly ventrad to the 
latter. In this way there is formed on each side of the complex centrum, a 
transversely disposed groove, open ventrally and distally, and bounded in front by 
the anterior division of the transverse process of the fourth vertebra, and behind by 
the posterior division in conjunction with the transverse process of the fifth vertebra. 
The sixth vertebra, and not the fifth as in the more normal s])ecies of Cryptopterus, 
carries the first pair of ribs, 
A radial nodule suturally attached to the side of the complex centrum is present, 
and also a dorsal lamina in the usual position and with the usual relations to the 
posterior cardinal vein and the transverse process of the fourth vertebra. 
The air-bladder is somewhat reniform in shape, with its long axis transversely 
disposed and the contour of its anterior wall interrupted by a deep emargination in 
the median line. The mesial portion of the organ lies across the ventral surfaces of 
the complex and fifth vertebral centra, but the more laterally situated parts occupy 
the grooves enclosed by the modified transverse processes, and are widely separated 
from the external skin. In a specimen five inches long the antero-posterior extent 
of the bladder was about 6 mm,, and its transverse dimension about 10 mm. On 
