92 
ORNITHOLOGISTS' COMPENDIUM. 
is regularly periodical, the vernal or spring migration being in the 
northern hemisphere, northward, the autumnal migration southward, 
but vice versa in the southern hemisphere. The migrations of many 
birds, however, are irregular or erratic, being prompted by the neces- 
sity of finding the requisite food-supply. The Passenger Pigeon [Ec- 
topistes migratoria), American Robin (Merula migratoria), Cedar-bird 
(Ampelis cedrorum), etc., are migratory in this sense; while the Tana- 
gers, Orioles, and others, which pass the summer only in northern 
latitudes and the winter entirely within the tropics, are periodical 
migrants. 
Mimetic (L. mimet'icus), a. Imitative ; pertaining to or given to mimicry. 
' n. Mockery, or imitation of voice, shape, color, etc. 
Mim / esis (L), The term protective mijnicry is applied to animals which 
Mim'icry, imitate in color or shape objects by which they are 
surrounded or species with which they are associated. 
Mir'ror (L. spec'ulum), n. A name occasionally given to the speculum 
or metallic wing-spot of ducks, etc. 
Moriipilose (L. mollipilo'sus), a. Softly dovny. 
Monogamous, a. Mating with a single individual of the opposite sex. 
Applied to species which pair. Those in which the male assists in 
incubation and rearing the young are doubly monogamous. 
Monogamy, n. The state of pairing, or having a single companion. 
Mon'ograph, n. A special treatise upon a given subject ; as, a Mono- 
graph of the Woodpeckers, a Monograph of the Genus Sylvia, a Mono- 
graph of the Great Auk, etc. 
Monomorph/ic, a. Of essentially the same or similar type of structure. 
(Opposite of polymorphic.) 
Monotonous, a. Laying a single egg, as the Petrels, Auks, etc. (Same 
as uni parous.) 
Morphological, a. Pertaining to morphology. 
Morphology, n. The science which treats of the laws of form, or the 
principles of structure. Morphology is the basis of homology, while 
analogy is based upon teleology. 
Mouse Gray (L. muri'no-gris'eus ; murinus), n. (Lamp-black -f- white -{- 
sepia.) (Plate II. fig. 11.) 
Moustache' (L. mys'tax), n. In descriptive Ornithology any conspicuous 
stripe on the side of the head beneath the eye. 
Mu'cronate (L. mucrona'tus), a. Spine-tipped, as the rectrices of the 
Chimney-swift {Chcetura pelagica). 
Mucron'ulate (L. mucronula'tus), a. Tipped with small points. 
Multip'arous, a. Producing many eggs. 
Mum'my Brown, n. A bright brown color, nearly intermediate in tint 
between burnt umber and raw umber. The pigment of this name is 
prepared from ground Egyptian mummies. (Mummy; also, sepia -f- 
raw umber + burnt sienna.) (Plate III. fig. 10.) 
Mu'ral (L. mura'lis), a. Pertaining to a wall. 
