52 University of California Publications in Zoology. (Vou. 5 
was composed of tules and stems of this water plant. These had 
been accumulated until the top of the floating mass was three or 
four inches above the surface of the water. In a slight depres- 
sion there were four considerably incubated eggs. Four nests 
were located within an area of 100 square feet, but only two of 
them contained eges. The eggs were nearly covered by strands 
of decaying vegetation which the birds had evidently placed there 
to conceal them. We estimated that there were about 100 pairs 
of adult grebes on the lake. 
Ten adults and ten young were secured and preserved. <A 
young female, 614 inches long, in full natal plumage (No. 6879, 
Coll. J. G.) presents the following coloration: Lower surface 
plain white, becoming dusky along the sides ; upper surface sooty, 
marked with narrow longitudinal whitish lines; there are seven of 
these down the back, the medial three being most clearly indi- 
eated; four rather broader white stripes extend down the back of 
the neck, and are indicated brokenly over the top of the head; a 
white line starts back from the middle of the forehead, but 
divides into two which diverge around the bare pinkish crown 
spot; there are flecks of dusky along the malar region, but none 
on the throat; the bill is crossed vertically by two dusky bands, 
the remainder, including the tip of both mandibles, being horn- 
color. 
The adult with the brightest chestnut on the sides is a male, 
and one of the females has considerable white in the throat. But 
I am unable to see any constant sex difference in the plumage of 
either adults or young. 
Sterna forsteri Nuttall. Forster Tern. 
Forster terns were seen daily from July 28 to August 2, 1905, 
flying back and forth over the marshy east end of Bear lake. 
Four adults were secured, but we obtained no evidence that the 
species was breeding; yet this was altogether possible. 
Hydrochelidon surinamensis (Gmelin). Black Tern. 
A single individual of this species was seen several times over 
the east end of Bear lake, July 30, 1905. It was usually flying 
in the wake of a company of Forster terns, as they coursed up 
