NEW SPECIES OF trout FROM LAKE TAHOE. 
27 
Body shaped as usual among trout, perhaps somewhat flatter than ordinary, the width contained 
times in the depth near middle of body. Snout short and rounded; maxillary weak, narrow, and 
short, scarcely extending beyond a vertical through posterior edge of orbit. Opercles and branchiostegals 
rather thin and papery. Jaws weak; their teeth small and sharp; teeth in bands on vomer and pala- 
tines; 2 rows of 5 teeth each on the tongue; basibranchials smooth and without teeth. Branchiostegals, 
II. Gillrakers on first arch, 74-12, slender and pointed. Lateral line almost straight from opercle to 
caudal. Scales very thin, not deeply embedded, moderate in size on the sides, extremely small on 
middle of back anterior to dorsal fin and on throat and abdomen. Fins all comparatively thin and 
frail, not like those of trout from mountain streams; pectorals and ventrals sharply pointed; dorsal 
and anal with slightly concave edges; caudal deeply cleft, the lobes pointed; adipose fin thin, narrow, 
and elongate. 
Color in alcohol, dusky above, silvery on the sides, white beneath; dorsal and caudal fins dusky; 
anal somewhat dusky toward the border; pectorals and ventrals immaculate; no spots or bars on the 
head, body, or fins. On close examination the scales are observed to be silvery, those on the dorsal 
region closely speckled with black, those beneath with but little luster. 
The type, which will be deposited in the United States National Museum, is a specimen measuring 
323 millimeters in length, collected near Brockway, Lake Tahoe, Cal., August 23, 1912, by Mr. W. P. 
Lyon. 
No external sex differences appear, a male and female being alike in all outward respects. Three 
of the specimens have 5 rows of small, elongate spots on the dorsal fin, some small spots on the caudal, 
and a few poorly defined spots on the dorsal part of the body. The latter did not become visible until 
the specimen had been in alcohol for some time. In the new species the maxillary averages 0.114 of the 
length to base of caudal; in 5 . henshawi, 0.145, exhibited by 10 examples from Lake Tahoe, 0.141 
in 10 from the Truckee River, and 0.14 in 10 from Pyramid Lake, the sexes being equally represented. 
The gillrakers differ as follows: 
The difference becomes more evident when the entire number on both limbs of the gill arch is 
taken into account, and this method of enumerating them is the better, as it is usually difficult to 
determine whether the one at the angle should be included with those above or below. 
vS 
regalis. 
S. henshawi. 
Number of gillrakers 
19 
20 
21 
22 
23 
24 
25 
Number of specimens 
I 
r 
2 
4 
ir 
13 
2 
Two examples of the new form have 42 and 57 casca, respectively. 
