MOOR-BUZZARD—MOOR-HEN 589 
result of arrested development of the anterior cranial vesicle. 
Irregular growth of the "AMNION frequently has a disturbing in- 
fluence upon various parts of the embryo, and thus abnormalities of 
the tailfold (EMBRYOLOGY, p. 201) produce hind limbs abnormal in 
shape and position, a crooked vertebral column and so on. Double 
or treble monsters, partial or even perfect twins, or triplets, may be 
due to any one of three causes :—two or three yolks, each with its 
own blastoderm (p. 200) in one common shell; two blastoderms 
with one yolk; or one blastoderm upon a single yolk, split by a 
subsequent injury, each portion of it producing a more or less 
complete counterpart of an embryo or portion of it. M. Dareste 
has been able to shew beyond doubt that portions of the blasto- 
derm artificially split off, or even parts of more advanced embryos 
will occasionally continue growing into a part at least of that 
organ, of which the respective embryonic cells were the normal 
substratum ; in the case of two blastoderms upon a single yolk, 
complete though more or less united embryos will be the result. 
According to the present state of our knowledge it is not justifiable 
to explain partly multiple monstrosities by the assumption of a fusing 
of originally separate embryos, but by a splitting of the blasto- 
derm, and if that takes place very early and is complete, each of 
its halves, which in Mammals have little or no yolk, may produce 
an independent embryo, so that in such a case the flippant saying 
that ‘‘ A twin is only the other half” happens to be true. 
MOOR-BUZZARD, the common name in England, in days 
when the bird was not scarce, for what is called in books the 
Marsh-HARRIER. 
MOOR-COCK, MOOR-FOWL and MOOR-POULT, old English 
names of the bird now well known as the Red GROUSE; but 
MOOR-HEN is the commonest name of a common bird, often 
called Water-hen, and in books sometimes Gallinule. An earlier 
English name was Moat-hen, which was 
appropriate in the days when a moat was 
the ordinary adjunct of most considerable 
houses in the country, and this species 
its ordinary denizen. It is the Gallinula 
chloropus of ornithologists, and so well 
known as hardly to need description. 
About the size of a small Bantam-hen, but with the body 
much compressed, as is usual with members of the Family 
Rallide (RAL) to which it belongs, its plumage above is of a 
deep olive-brown, so dark as to appear black at a short distance, 
and beneath iron-grey, relieved by some white stripes on the 
flanks, with the lower tail-coverts of pure white—these last being 
very conspicuous as the bird swims. A scarlet frontlet, especially 
Moor-HEN. (After Swainson.) 
