1890 - 91 .] Drs Symington & Thomson on Defective Ossification. 279 
This remarkable contraction of the chest was found to depend 
entirely upon the arrested development of the ribs ; the latter are 
less than half the normal length at birth, while the costal cartilages 
are of the full average size. 
The longest, or 7th rib, measured along the convexity 3 "2 cm. in 
the specimen, 7*8 in the normal. 
The longest, or 7th costal cartilage, measured along the convexity 
5*4 cm. in the specimen, 6 in the normal. 
The ribs are sharply curved, and join their cartilages at an 
angle. Externally this angular junction is responsible for the 
furrow mentioned above, while on the internal or pleural aspect it 
forms a prominent projection, like that of a rosary. 
Further, as a result of their shortness, the ribs are more horizontal 
than normal, and the costal extremity of each is slightly cupped. 
The 7 th rib and its cartilage were examined microscopically ; the 
appearances observed will be afterwards referred to. 
The sternum is of full size and is well formed ; it consists 
entirely of normal hyaline cartilage, without any trace of osseous 
nuclei. 
The Pelvis, like the thorax, is remarkably contracted in all its 
diameters, especially, however, in the conjugate at the brim, which 
is less than half of the same diameter at birth. 
Conjugate at the brim in the specimen, 1*3, in the normal 2 '8 cm. 
Transverse, „ „ „ 2 -8 „ „ 3 -6 „ 
Interspinous diameter, . . . 5 '6 ,, „ 7 '4 „ 
The pelvis is, therefore, generally contracted and flat. Further, 
the diminution in the size of the pelvis is shown by the fact that 
the tip of the coccyx projects 3T cm. below the level of the lower 
border of the pubic symphysis, and 2 cm. below the level of the 
ischial tuberosity. 
The above alterations are entirely due to the early arrest of the 
osseous growth of the constituent elements of the ossa innominata, 
while the sacro-coccygeal portion of the spine is of the usual size and 
length, being so independently of ossification. The innominate 
bone, as examined after dehydration and clearing in naphtha, was 
found to consist almost entirely of cartilage, the normal osseous 
