in the Jardin des Plantes in Paris in 1853,
and many parallel instances are on record.

Classification.--We shall attempt no scientific discussion of the
causation or embryologic derivation of the monster, contenting
ourselves with simple history and description, adding any associate
facts of interest that may be suggested. For further information, the
reader is referred to the authors cited or to any of the standard
treatises on teratology.

Many classifications of terata have been offered, and each possesses
some advantage. The modern reader is referred to the modification of
the grouping of Geoffroy-Saint-Hilaire given by Hirst and Piersol, or
those of Blanc and Guinard. For convenience, we have adopted the
following classification, which will include only those monsters that
have LIVED AFTER BIRTH, and who have attracted general notice or
attained some fame in their time, as attested by accounts in
contemporary literature.

CLASS 1.--Union of several fetuses. CLASS 2.--Union of two distinct
fetuses by a connecting band. CLASS 3.--Union of two distinct fetuses
by an osseous junction of the cranial bones. CLASS 4.--Union of two
distinct fetuses in which one or more parts are eliminated by the
junction. CLASS 5.--Fusion of two fetuses by a bony union of the
ischii. CLASS 6.--Fusion of two fetuses below the umbilicus into a
common lower extremity. CLASS 7.--Bicephalic monsters. CLASS
8.--Parasitic monsters. CLASS 9.--Monsters with a single body and
double lower extremities. CLASS 10.--Diphallic terata. CLASS
11.--Fetus in fetu, and dermoid cysts. CLASS 12.--Hermaphrodites.

CLASS I.--Triple Monsters.--Haller and Meckel were of the opinion that
no cases of triple monsters worthy of credence are on record, and since
their time this has been the popular opinion. Surely none have ever
lived. Licetus describes a human monster with two feet and seven heads
and as many arms. Bartholinus speaks of a three-headed monster who
after birth gave vent to horrible cries and expired. Borellus speaks of
a three-headed dog, a veritable Cerberus. Blasius published an essay on
triple monsters in 1677. Bordenave is quoted as mentioning a human
monster formed of three fetuses, but his description proves clearly
that it was only the union of two. Probably the best example of this
anomaly that we have was described by Galvagni at Cattania in 1834.
This monster had two necks, on one of which was a single head normal in
dimension