258 THE Wirson BuLteTIN—Nos. 76-77. 
Verrill gives the measurements of B. p. rivierei eggs as 
1.80x1.50 to 1.85x1.55. 
DESCRIPTION OF EGGS—Someone professes to see only two 
points of interest in a bird’s egg—‘‘One is what the egg is in, 
the other is what is in the egg.” However, there are some 
very good people interested in the shell. Fragile, exquisitely 
beautiful specimens, more precious to their possessors than 
the finest old china, have passed from one generation of oolo- 
gists to another, gems that love or money could not buy. A 
series. and sometimes the eggs of a set, show considerable 
variation in shape, ranging from elliptical ovate to oval; short 
ovate being the most typical, and ovate-pyriform the rarest. 
Of the latter type are a set collected at Chippewa, Co., Mich., 
and described by C. F. Stone; and another taken at Salem, 
N. J., by W. B. Crispin. 
The ground color runs from pure white to grayish, bluish, 
greenish, and cream-white, grayish-white being the most fre- 
quent; the “dirty-white” ground color of most writers being 
exactly what it seems—dirty, soiled by the bird’s feet. The 
shells exhibit almost maximum range and development of col- 
oration in North American Raptores, and a typical set very 
rarely contains more than two eggs of the same type; not 
infrequently all are different. In sets of two or three, one 
egg is almost certain to be of the gray or lavender sub-shell 
type and the remainder overlaid with pigment. In sets of four, 
the second egg may be an example of heavier sub-shell mark- 
ings or lightly overiaid with russet or brown. The eggs of 
this species also present the odd characteristic of confluent 
pigmentation at the smaller end or apex as frequent as at the 
base. Six fairly distinct types are discernable without resort 
to combinations: (a) Immaculate, or with faint shadow mark- 
ings. Not so infrequent as generally supposed. (b) Semi- 
obscured sub-shell markings of impure black or red and violet, 
producing the different grays, and the lilac-gray, heliotrope 
and lavender. Present in at least one egg of almost every set. 
(c) Sub-shell markings and surface stains of ecru-drab, fawn 
and drab. A rare form of coloration. (d) Surface pigmenta- 
