318 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
borders develop a raised rim, and the planes of the surfaces, contributed by the two 
bones superiorly on either side, look upward and outward, the reverse being the case, 
of course, beneath. The postero external angles, as well as the hinder border, are 
thickened and undulating for the articulations of the heads of the ventral fin-rays. 
There is, also, a characteristic process developed inesially on this border, into the 
formation of which each pelvic bone takes an equal share; above it is bilid, directed 
upward and backward, and compressed anteroposteriorly; below it is peg-shaped and 
directed in the same degree forward and downward. 
I fail to find any bony nodules representing the actinosts between the ventral 
fin rays and the pelvic bones in this fish: and the rays themselves seem to be con- 
structed upon the same plan as the pectoral ones, being retained in their positions by 
firm ligaments and the skin. The outer one, however, on either side differs materially 
in form, being spoon-shaped, with the concavity against the next ray on its inner side. 
It also develops an inturned process, which curves over the next two or three rays. 
This double arrangement seems 
designed to strengthen the inner 
rays and assist to keep them in 
their position. 
These pelvic bones are seen only 
in part in the accompanying ligure 
of the skeleton of M. dolomieu{ plate 
44), but this statement does not 
apply to the remainder of the oste- 
ology of the body and tail of this 
bass. 
Omitting a study of the scales 
of Micropterus , which closely re- 
semble those of most other forms 
of the higher teleostean fishes, we 
have still to briefly consider the 
skeleton of the body and the skele- 
ton of the tail. 
Counting the one from which 
the urostyJe springs, Micropterus seems invariably to have thirty vertebra in its spinal 
column. When I make this statement I am aware of the fact that in my paper on 
Amia calva thirty- two was the number reckoned, but after carefully recounting these 
on two perfect skeletons now before me, representing both species of the genus, I am 
satisfied that there are but thirty of these bones. Fifteen of these vertebrae belong 
to the abdominal portion of the column, and each one supports a pair of ribs, all of 
which in their turn, save the last five pair, have epipleural appendages. The atlantal 
pair articulate with the vertebra at the very base of the neural arch, but as we pro- 
ceed backward they gradually recede from this position so as to finally spring from 
beneath the transverse processes on the under side of the vertebra. This condition is 
characteristic of a great many of the osseous Ashes. The neural and haemal arches of 
this form are completely anchylosed with the vertebral elements, and in the best- 
developed segments, both superior and inferior, post- and pre-zygapophyses are 
present. 
Fig. 7. — Sketch of the inner aspect of left half of shoulder girdle and 
l)3Ctoral limb of H. salmoides. Pst. T posttemporal ; Psto. T ., 
posterotemporal ; Hyp. c., hypercoracoid ; Hyo. c., hypocoracoid ; 
P. Sc., proscapular ; T., teleo temporal; T lower teleotemporal ; 
Ast., actinosts; Pf., pectoral fin. 
