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R Ruggles Gates. 
as a monstrosity.” Featherless birds are not unknown, or only 
certain pterylae may be affected, as in the bareneck fowls (Davenport, • 
1914), a condition which is dominant in crosses. A well known 
case cited by Stebbing is that of Dorippe dovsipes with four legs, 
and four more small ones on its back. It is therefore clear that 
even mutational monstrosities have played their part in the 
production of species, and it is quite certain that if some family and 
ordinal characters could have been seen at their first appearance 
they would have been considered monstrosities. 
Dwarfs and giants are as common in animal species as among 
plants. A dwarf-bearing strain of guinea pigs is described by Miss 
Sollas (1914). It produced in all 192 normals to 64 dwarfs, the latter 
evidently behaving as a simple Mendelian recessive. The study of 
inheritance of melanism in British Lepidoptera has in recent years 
attained considerable proportions. These results can only be 
touched upon here, but they show that the melanic variety usually 
behaves as a Mendelian dominant, sometimes a recessive, and in 
certain cases gives blending inheritance. A number of cases are 
discussed by Bateson (1913, p. 135 ff.) 
Sumner (1917) has obtained mutations in the Californian deer- 
mouse, Peromyscus maniculatus, both in the wild state and in 
captivity. A “ yellow ” mutation of P.m. gambeli was trapped at 
LaJolla, California in 1914. The normals have a dark gray pelage 
and black eyes. In cages a total of 14 normal to 7 yellow appeared, 
in broods which were traced back to a single pair of grandparents. 
There were no other yellows among over 400 gambeli bred. Hence 
the appearance of the yellow was due to a recessive mutation 
factor carried in the two grandparents. Castle has reported 
similar “yellow sports” in wild species of Microtus. 
