32 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
ter of the lake vary from 40 to 80 feet in depth. The summer tempera- 
ture is between 50 and 60 degrees Fahrenheit; the winter, probably not | 
below 40 degrees ; the deeper parts, probably above 46 degrees. 
u Until the beginning of the present century there was free access 
to the sea, and probably a few centuries ago the Loch Leven trout was 
thoroughly migratory. About fifty years ago the loch was reduced to 
its present size, 1,000 acres being drained, the surface lowered 6 feet, 
and sluices constructed at the. outlet for the accommodation of mills 
on the Fiver Leven below. The S. levenensis is found in the River 
Forth, in Loch Lomond, and other lakes of the west coast of Scotland, 
and also those of the northwest of England. It crosses readily with 
S. trutta (sea trout) and 8. fario (common trout) ; the offspring are fer- 
tile. It hybridizes with 8. salar. The offspring of S. levenensis (female) 
and 8. salar (male) have hitherto been sterile. Those I have are now in 
their fourth year. The offspring of 8. salar (female) and 8. levenensis 
(male) which I have are as yet too young to determine sterility, but 
this cross is much easier made and the ova more prolific than in the 
former. 
u The Loch Leven trout still retains many characteristics of a sea-going 
salmonoid, such as the parr marks, the silvery smolt livery, the forked- 
tail grilse stage, with its small proportion of spawners, diminutive eggs 
(40,000 to a gallon), and tender, delicate embryos; and its mature state, 
with a square tail, strongly developed hook on the under jaw of the 
males, large eggs (27,000 to a gallon), producing strong, well-formed, 
vigorous embryos. The practical difference between 8. levenensis and 
S.fario is that the former has a much larger number of caecal append- 
ages and a stronger stomach, enabling it to crush the Limnia pereger , 
on which it largely feeds.” 
At a meetiug of the Linnean Society of London, in January, 1887, 
Dr. Francis Day read a paper on the Loch Leven trout, in which he 
said: “ These fish are known by their numerous caecal appendages, and 
up to their fourth or fifth year they are of a silvery gray, with black 
but no red spots. Subsequently they become of a golden purple, with 
numerous black and red spots. Undergrown ones take on the color of 
the brown trout [common English brook trout, Salmo fario ?]. Remove 
these fish to a new locality, and they assume the form and color of the 
indigenous trout. In 1883 a salmon parr and a Loch Leven trout were 
crossed, and the young have assumed the red adipose dorsal fin, and 
the white-edged margins to the dorsal and ventral, also the orange edges 
to both sides of the caudal — all colors which are found in the brook 
trout, but not in the salmon or Loch Leven trout. The maxilla in this 
form not extending to behind the eye, the absence of a knob on the 
lower jaw in old breeding males, and the difference in the fins from 
those of Salmo fario , were shown to have been erroneous statements.” 
Washington, D. C,, May 5, 1887. 
