-60 TJ. S. BUREAU or FISHERIES. 



some parasites. There is scarcely a fish that swims that is not more 

 or less infected by some sort of parasitic worm, and in this respect 

 the Yellowstone fish do not appear to be worse than the fish of many 

 other lakes in the country. 



LOCH LEVEN TROUT (SALMO LEVENENSIS). 



The Loch Leven trout " of Great Britain was introduced into the 

 United States from Scotland in 1885 and subsequent years. It is 

 somewhat closely related to the European brown trout {Salmo fario) , 

 and has been artificially crossed with that species in the United 

 States, so that it is sometimes difficult to find the purebred Loch 

 Levens in fish-cultural establishments at home. 



DESCRIPTION. 



The body of the Loch Leven is more slender and elongate than that 

 of the brown trout, its greatest depth contained four and one-fourth 

 to four and one-half times in the total length without caudal. Caudal 



Fig. 21. — Loch Leven trout (Salmo levene^isis). 



peduncle slender, its least depth three-eighths of the greatest depth 

 of the body and equal to length of snout and eye combined. The 

 head is rather short and conical, its length two-ninths to one-fifth 

 of the total length without caudal. The snout is one- fourth or 

 slightly more than one-fourth as long as the head. The interorbital 

 space IS somewhat convex, its width equal to three-fifths of the 

 length of postorbital part of head. The eye is of moderate size, its 

 long diameter contained five and one-half to six times in the length 

 of the head and equaling about twice the greatest width of the max- 

 illa. The maxilla reaches to or slightly beyond the posterior margin 

 of the eye. Teeth rather strong, those in the intermalillary and man- 

 dible the largest, triangular head of vomer with two or three in a 

 transverse series at its base, teeth on the shaft of the vomer usually 

 in a single, partially zigzag, persistent series. Mandable without a 

 hook and but little produced even in breeding males. 



Anterior end of dorsal base distant from tip of snout about as far 

 as posterior end from base of caudal; the dorsal fin higher than 

 long, its base one-eighth of total length without caudal, its longest 

 ray equal to longest ray of anal fin. The anal fin is much higher 



1* Food and Game Fishes of New York. Bv Tarleton H. Bean. In the Seventh Report 

 of the New York Forest, Fish, and Game Commission. 1901 (1902), p. 336. Albany. 



