1888.] Mr M. Brown on Arrested Twin Development. 467 
From the xiphisternum, which was hard and apparently osseous, 
there projected downwards and to the left a hony spine (about 
2 inches long), whose free end was rounded, and had attached to it 
the modified scapulae by a strong ligamentous hand (about J of an 
inch long). The scapulae had apparently become welded together 
into one bone along their dorsal aspects, they were attached to the 
sternal spine at the acromial region, while their bodies projected 
downwards and towards the body of the autosite as a triangular bony 
plate. The xiphoid spine was believed to represent the rudimen- 
tary clavicles, which in development had become incorporated with 
each other and with the xiphisternum. 
At the modified scapulo-sternal joint there was the freest possible 
movement, while that at the shoulder-joints was extremely limited. 
The upper extremities were carefully described, and the measure- 
ments of the various bones given. These were somewhat rudimen- 
tary, and the joints between them ankylosed. The right hand 
possessed four fingers, stiff, webbed, and almost fully extended, but 
wanted the thumb ; the left possessed all five digits, but these were 
claw-like and webbed. 
The pelvic girdle consisted of sacrum (with coccyx) and innominate 
bones, all of which were small and somewhat modified. It was 
attached to the autosite by a strong ligament, which extended from 
the region of the symphysis pubis upwards to the xiphisternum, 
with which it was mainly connected; a part of it, -however, spread 
out in the right epigrastrium of the autosite, and ended in the 
tissues of its abdominal wall. 
The leg bones (of which exact measurements were given) were 
like those of the arm rudimentary, and their joints were ankylosed. 
The feet were, although talipedic, well formed, and bore the usual 
number of toes. 
It might be imagined that the presence of the parasite would 
cause uneasiness or even ill-health in the boy; on the contrary, how- 
ever, he is strong and active, and appears to suffer no inconvenience 
from its presence. 
8. On Numerical Solution of Equations in Variables of 
the ?^th Degree. By Lord M‘Laren. 
