354 BONES OF LOPHIUS PISCATORIUS — MORROW. 
slight downward curve, and on the sixteenth it has attained its 
normal leneth and angle, and from this, to and including the twen- 
ty-seventh centrum, the spines gradually decrease in length and 
angle. The hzemal spine* of the twenty-eighth centrum is much 
elongated, and is almost parallel with its neural spine, it extends 
posteriorly beneath the twenty-ninth centrum for two-thirds of 
the length of the latter. 
On the twenty-ninth centrum there is no hzmal spine, unless 
a somewhat thick and flattened edge on its posterior extremity 
may be said to represent it. In the wing-shaped processes at 
each side there is a foramen for the vessels, slightly posterior 
to the termination of the hzmal canal proper. 
74 & 75. Dorsal fins. This fish has two dorsal fins, the first 
containing six spines, two of which are close together and 
near the nostrils, and are supported by a very peculiar dermal 
longitudinal spine situated between the turbinal or nasal bones ; 
looking upon the superior surface of this spine, at its anterior 
extremity there is a narrow perforated projection which joins 
the apex of a flat kite-shaped process, the posterior extremity 
of which terminates in a sharp point curved slightly above the 
general line of the spine, and beneath which the spine has a 
flattened superior edge widening to its posterior extremity where 
it is quite thin and flat. On its anterior half the spine has at 
its anterior extremity, vertically, a very thin and deep plate, 
which is strengthened by the flattened edge and process above 
mentioned ; this thin plate at its anterior inferior extremity 1s 
rounded, and curves posteriorly towards the middle of the spine 
and there disappears. As already mentioned the anterior por- 
tion of the longitudinal spine lies between the turbinal bones, 
and its anterior extremity is slightly in advance of the superior 
processes of the maxillaries; its posterior extremity extends to 
nearly the centre of the forks of the frontals. The length of the 
spine varies in different specimens, a small fish having sometimes 
a proportionately longer spine than a large one. The spine is 
enveloped by muscles which control its movements, as well as 
* In one specimen before me, the length of the spine is nearly one and a quarter inches, 
while that of the twenty-nluth centrum is one and five eighths inches, 
