THE SKELETON OF THE BLACK BASS. 
319 
As the accompanying' figure, shown in plate 44, of the skeleton of this bass is 
reproduced from a photograph of a carefully dissected and dried skeleton, it will be 
observed that a little ligamentous material is remaining, and some of the bony fin- 
rays and spines are very slightly unparallel, but this fact will lead no one astray, as 
it is quite evident which bones have become so while the skeleton was drying. The 
arrangement of these osseous fin-rays and inter spinous bones practically agrees with 
those elements as we have long known them to exist in all ordinary bony fishes, as in 
the common yellow perch for example {Perea). 
The skeleton of the tail in Micropterus is of the typical homocercal type, and devel- 
ops a very completely ossified urostyle, directed upward and backward at an angle 
of about 45 degrees, with a markedly straight vertebral column, as is plainly to be 
seen in plate 44. The osseous expanded portion of the tail is in the vertical plane, and 
is thus modified in order to give support to the bony rays of the caudal fin. Possibly 
Fig. 8. — Outer aspect of part of shoulder girdle and pectoral fin of M. salmoides. Natural size and drawn 
by the author from his own dissections. Ps., proscapular, with other lettering the same as in fig. 6. 
I may formerly have considered that this expanded portion contained two vertebra ?, 
and it may. In this case the count for tliirty-two vertebrae in the column would be 
correct; but in the reckoning given above this part is omitted and only the vertebrae 
taken into consideration which possess the true form of those bones. 
These terminal modified vertebrae are known as the hypural plates, and they are very 
broad and perfect in M. salmoides. The caudal osseous fin-rays are ligamentously 
attached to the posterior margins of the hypural plates in the simple manner seen 
among all ordinary teleostean fishes generally. Both above and below, the 29th and 
30th vertebrae have narrow and elongated hypural plates springing from them, and 
the 29th has the haemal and neural spines in addition thereto, but these last are absent 
in the 30th vertebra. These hypural spines support distally the outer and very 
rudimentary fin-rays of the tail. Counting from before backward, it is the third 
hypural plate upon either side that developed the urostyle spoken of above, and which 
