1895.] Zoology. 861 
project 3 mm. beyond the nose. Tragus long, slender, and slightly 
arcuate. Wings attached to feet near base of toes. 
Measurements (from alcoholic type (9 ad.) in good condition).— 
Total length, 82 mm.; head and body, 42; tail, 41; head, 17.5; ear 
from inner basal angle, 16 ; tragus from inner attachment, 8 ; humerus; 
23; forearm, 35.5; thumb, 7; third finger, 57; fifth finger, 46; tibia, 
17; foot, 8. C. Harr Merriam. 
Migrations of the Lemming.—A valuable account of “ Myodes 
lemmus, its Habits and Migrations in Norway,” has been published 
by Prof. R. Collett, of Christiania. The nature and habits of the lem. 
ming are described, and their suicidal migrations discussed on a basis 
of the author’s personal knowledge of the lemming. The migrations 
seem to be due to over-population. During certain years an abnormal 
fecundity takes place among these creatures, and the consequences of 
this multiplication is given by the author as follows : 
“The enormous multitudes require increased space, and the individ- 
uals, which, under normal conditions, have each an excessively large 
tract at their disposal, cannot, on account of their disposition, bear the 
unaccustomed proximity of the numerous neighbors. Involuntarily 
the individuals are pressed out to the sides until the edge of the moun- 
tain is reached. In a short time they enjoy themselves there, and the 
old individuals willingly breed in the upper region of the forests, when, 
at other times, they are entirely wanting. New swarms, however, fol- 
low on; they could not return, but the journey proceeds onwards down 
the sides of the mountains, and when they once reach the valleys they 
meet with localities which are quite foreign to them. They then con- 
tinue blindly on, endeavoring to find a home corresponding to that 
they left, but which they never regain. The migratory individuals 
proceed helplessly on to certain death. The writer thinks it probable 
that the wandering instinct developed in migratory years is of distinct 
service to the species in reducing surplus population. 
The Brain of Microcephalic Idiots.—A paper embodying the 
results of a thorough examination of the brains and skulls of two typ- 
ical microcephals, by Prof. D. J. Cunningham and Dr. Telford-Smith, 
has just been published in the Transactions of the Royal Dublin So- 
ciety. The authors accept the view arrived at by Sir George Humph- 
rey, from the examination of microcephalic and macrocephalic skulls, 
viz.: “ There is nothing in the specimens to suggest that the deficiency 
in the development of the skull was the leading feature in the deform- 
ity, and that the smallness of the bony cerebral envelop exerted a com. 
