328 MR. E. W. SHANN ON THE 
carefully, and with the result that I still maintain that the 
mesio-ventral portion is continued to the extremity of the tail 
in that species just as has been described above for Teleosteans 
in general. 
There remain yet to be considered the small cylindrical muscles 
known as carinales. These may be absent, and, when present, 
exhibit considerable variety in their extent. The upper pair, 
supracarinales, run parallel to one another along the mid-dorsal 
line, separating the mesio-dorsal portions of either side of the 
main lateral muscle-masses. They take origin on the occiput in 
the Cod (Owen), whence they run to the first dorsal, and reappear 
again in the interspaces between the dorsal fins; in Periophthal- 
mus they arise slightly behind the skull from the neural spines, 
and traverse the interspaces between the dorsal fins ; in Amiwrus 
they only appear behind the first dorsal fin, and MeMurrich 
describes them as “‘formed by the union of slips arising by tendons 
from the spinous processes.” They are separated by strong fasciz 
from the main masses of the lateral muscles, but retain their 
original metameric segmentation. Functionally they act, accord- 
ing to their position, as elevators or depressors of the dorsal 
fin-rays. They may be regarded as specialised modifications of 
the lateral muscle, just as are the other fin-muscles. 
The lower pair, infracarinales, are similar in nature to the 
foregoing muscies, and, when present, divide the mesio-ventral 
portions of either side of the lateral muscle. Both Owen and 
MeMurrich, who have described them, agree that they may be 
divided into an anterior and a posterior section. The latter 
extends from the posterior end of the anal fin to the base of the 
caudal, and between the two anal fins where such occur. The 
former extends from the anterior end of the anal fin to be~ 
inserted on the posterior face of the pelvic bone (ischium, Owen) ; 
hence they describe it as the “ retractor ischii,” and Owen goes 
so far as to describe in the Perch the “protractor ischii” as a 
still further anterior prolongation of the same muscle. 
A difficulty now arises. In many Teleosteans, especially in 
forms whose pelvic girdles are situated far forward, the “ retractor 
ischii” a short distance behind its origin on the posterior aspect 
of the pelvic bone becomes inseparably fused with the mesio- 
ventral portion of the lateral muscle ; or, in other words, part of 
the mesio-ventral portion forms in many cases the “ retractor 
ischii.” It would seem that the latter condition is more primitive 
than that where the “retractor ischii ” is composed of a carinalis 
muscle, which has been noted as a secondary modification of the 
lateral muscle. Yet the ‘“vetractor ischii” composed of an 
infracarinalis occurs for the most part in Teleosteans with 
abdominal pelvic fins, that is to say, in the more primitive 
forms; and vice versa. the (presumably) more primitive condition 
of the ‘‘ retractor ischii” occurs in the more specialised 'Teleosteans. 
This interesting anomaly is beyond the scope of the present 
investigation ; it recalls frequent analogous occurrences in the 
