350 E. J. ALLEN AND E. -W. SEXTON. 
EXPLANATION OF PLATES. 
Plate I. 
Fic. 1.—Explanation of the signs employed in the diagrams. 
Normal Black, i.e. with both the black retinal and the white extra-retinal pigments 
present. 
black no-white, with the black retinal pigment present, the white pigment absent. 
Red normal, with both the red retinal and the white extra-retinal pigments present. 
Red no-white, with the red retinal pigment present, the white pigment absent. 
Normal Albino, with the white pigment present, the coloured retinal pigment absent. 
Albino no-white or Colourless, with both the coloured retinal and the white extra- 
retinal pigments absent. 
A black spot attached outside the large circles indicates that the animal 
carries the factor for Black. Similarly, a red spot indicates that the factor 
for Red is carried, a small black circle the factor for Albino, and a small red 
circle the factor for No-white. 
The small V-shaped sign outside the large circles means that it has not been 
determined whether the factor usually indicated in the position where the 
sign is placed is present or absent. 
Fic. 2.—The matings of the Albino female A.C. (Albino carrying the factors for Black 
and Red) with a Red male and a Black male. 
Cross A. (p. 275) with the male R.2 from Pure Red Stock. 
One brood, I, and the young from their inter-matings. 
Cross B. (p. 278) with the male K.A. Black carrying the factor for Red from Family 
K (p. 326 and Plate V). 
Four broods, II, III, 1V and V. 
Many of the young died before reaching maturity. The constitution of those 
which survived to be tested is shown when known. 
Plate II. 
Cross C. The mating of the Albino female A.B. (Albino, carrying the factors for 
Black and Red), with the All-White male R.I.; the brood resulting from this 
mating is designated VI. 
Cross B. The mating of the Albino female A.C. (from the same brood and of the 
same constitution as A.B.) with the male K.A. from the family K, shown 
on Plate V, Fig. 1, Black carrying the factor for Red; the brood from this 
mating is designated IIT. The number of the offspring resulting from the 
cross-mating of Brood VI, with Brood II, together with the sex, and con- 
stitution when known, of the surviving animals, are shown below. Animals 
to which no letter is attached could not be tested for constitution. 
II.D 1, 2, 3, 4, are broods from the mating of two animals of Brood If. 
The number of young is shown, and the sex of those which reached maturity, 
but not the constitution, as, except in two or three instances, they were not 
tested for the factors carried. 
Plate III. 
Fic. 1.—Mating of Albino with Albino ; offspring all Albino-eyed. 
The male (h) and the female (1) are both from the second brood of II.D. 
(p. 279, Plate IT). 
Fic, 2.—Mating of Albino carrying the factor for Black with Pure Red ; offspring all 
Black-eyed. 
The male (A-}+ B) is from the first brood of IIT.B. (p. 279, Plate I); the 
female (R) is VI.B.2.¢. (p. 314, Plate II). 
