ssea._--This rare affection was described
by Virchow, and named leontiasis ossea because of the disfigurement to
which it gives rise. It usually commences in adolescence as a diffuse
overgrowth first of one and then of both maxillae; these bones are
enlarged in all directions and project on the face, and the nasal fossae
and the maxillary and frontal sinuses become filled up with bone, which
encroaches also on the orbital cavities. In addition to the hideous
deformity, the patient suffers from blocking of the nose, loss of smell,
and protrusion of the eyes, sometimes followed by loss of sight. The
condition is liable to spread to the zygomatic and frontal bones, the
vault of the skull, and to the mandible. The base of the skull is not
affected. The disease is of slow progress and may become arrested; life
may be prolonged for many years, or may be terminated by brain
complications or by intercurrent affections. In certain cases it is
possible to remove some of the more disfiguring of the bony masses.

A less aggressive form, confined to the maxilla on one side, is
sometimes met with, and, in a case of this variety under our own
observation, the disfigurement, which was the only subject of complaint,
was removed, after reflecting the soft parts, by paring away the excess
of bone; this is easily done as the bone is spongy, and at an early
stage, imperfectly calcified.

A remarkable form of _unilateral hypertrophy and diffuse osteoma of the
skull_, following the distribution of the fifth nerve, has seen
described by Jonathan Hutchinson and Alexis Thomson.

#Chondroma.#--Cartilaginous tumours, apart from those giving rise to
multiple exostoses, grow from the long bones and from the scapula,
ilium, ribs, or jaws. They usually project from the surface of the bone,
and may attain an enormous size; sometimes they grow in the interior of
a bone, the so-called _enchondroma_.

The hyaline cartilage composing the tumour frequently undergoes
myxomatous degeneration, resulting in the formation of a glairy,
semi-fluid jelly, and if this change takes place throughout the tumour
it comes to resemble a cyst. On the other hand, the cartilage may
undergo calcification or ossification. The most important transition of
all is that into sarcoma, the so-called _malignant chondroma_ or
_chondro-sarcoma_, which is associated with rapid increase in size,
and parts of the tumour may be carried off in the blood-stream and give
rise to secondary