16 
On the Callorhynchus Australis. 
edge is a triangular piece corresponding to anchylosed 
epi-vertebral elements, which supports the soft rays of 
the first dorsal fin : these osseous supports are sustained 
by the anchylosed peri-vertebral elements of the cervical 
vertebra). Connected with this fin there is a vascular 
structure, which I consider to be an accessory organ 
of respiration ; it is situated betwixt the posterior rays of 
the dorsal fin and the spinal column. It consists of a fine 
net-work of vessels enclosed betwixt the two lasers of 
depressor muscles arising from the sides of the spinal 
column, and inserted into the triangular piece sustaining 
the fin. Although from want of time I was unable to 
detect any communication with the gullet, yet I have no 
doubt one exists, from being able to squeeze out the 
gaseous matter contained in this rudimentary lung; in 
fact, it is the air-bladder of the Chimera, and is placed 
on that part of the body best suited for the oxidation of 
the Huids contained in the vascular structure it incloses. 
It serves the fish in the essential movements of sinking 
o 
and rising to the surface; which is in others performed 
by the air-bladder situated within the body and below 
the spinal column. This hydrostatic machine is worked 
by the elevation and depression of the fin, which fills 
the cavity when drawn down,-and either produces con¬ 
densation of the gas sufficient to make the fish heavier 
than the water, or forces it out of the sac. The erection 
of the fin above allows the gas, by its elasticity, to ex¬ 
pand, when the body of the fish becomes specifically 
lighter than the water, and then rises. 
Skin .—The skin is soft and smooth, and lubricated by 
the secretion of a peculiar bilobate gland, situate in front 
of the head before the toothed organ of prehension : 
the lobes are about .an inch long and half an inch in a 
transverse diameter. From the external sides issue a great 
many large ducts, which are distributed to all parts of the 
