NATURAL SCIENCES OI' PHILADELPHIA. 
137 
while the gates are up, but as soon as they are closed and the water becomes 
still, they decline the fly, but will still take the bait ; at this time it is necessary 
to fish below the dam, where there is still a very rapid current from leakage and 
overflow. The brook trout, S. fontinalis, is taken in the same waters, and in the 
stiller waters above, a large lake trout, there called the Togue, which differs 
from the Salmo confinis of the northern lakes, by having a more deeply forked 
tail like the -S^. siskewei of Lake Superior. 
Another striking characteristic in the history of this fish, is the remarkable 
development, in the male, of the point of the lower jaw, or chin, whereby it be- 
comes elongated and hooked, during and previous to the seasons of sexual con- 
nexion and spawning, which are simultaneous in fishes. This peculiarity, 
which, so far as I am aware, has been heretofore considered to belong to the 
type of the genus alone, the Salmo salar, adds much force to the theory of 
Mr. Agassiz to which I alluded before, (and I believe I am correctly informed 
that he has advanced such a theory). This fact, which I can vouch for from 
personal observation as well as other undeniable testimony, will show the 
necessity of a very close and searching examination of the structure and 
anatomy of this fish, comparing it with the true salmon, before its new name is 
confirmed. This sexual development, so strictly analogous to the swelling of the 
neck in the genus Cervus among quadrupeds, seems to point to further research 
among other species of the genus, that is to say, whether there is nut a similar 
development, though less marked, through the whole family, as at present ar- 
ranged, or if found wanting in that portion of the genus with very minute scales, 
whether it may not characterise that portion consisting of Salmo salar, this fish 
and all those having large scales. I was struck the other day in looking over 
the figures of Richardson's Troat of the Arctic Regions, that there was more 
than one with the projecting lower jaw. Were not these fish taken during the 
spawning season? And may they not have received another name in the nor- 
mal state ? Of course the facts at present known are too scanty to found a 
theory upon, but should this suggestion ultimately prove to have a foundation 
in fact, it would be sufficient to authorise a division of the genus. 
Dr. Morris mentioned in connection with this subject, that he had observed 
in the common brook trout {Salmo fontinalis) a similar elongation of the lower 
jaw in the spawning season. 
June 2dth. 
Vice President Bridges ia the Chair. 
Twenty-nine members present. 
The Keport of the Secretary of the Biological Department was pre- 
sented. 
The by-laws reported by the Committee appointed March 30th, to 
draft a series of by-laws for the j^overnment of the Committee on Pro- 
ceedings, were read for the third time, and passed. 
Whereupon Dr. Fisher offered the following : 
Resolved, That all previous resolutions of the Academy^ prescribing 
the constitution, duties and powers of the Committee on Proceedings, 
be, and the same are hereby repealed. 
Which was considered and adopted. 
Dr. Leidy, by permission of the Academy, communicated the fact, that 
about one half of the chrysalides of the canker-worm {Endalimia), which had 
recently proved so destructive to the foliage of our shade trees, were infected 
by two species of Ichneumon. One of the latter is comparatively large ; and a 
single individual occupies the body of a canker-worm chrysalis. The other 
species is minute ; and numerous individuals occupy the interior of a chrysalis, 
1858.] 
