718 INDIVIDUAL VARIATION IN EQUUS ASINUS. 
outcome of the large number of dissections made by ourselves 
and by students under our supervision. We were hardly pre¬ 
pared to observe so much variation, and were struck by many 
Ruminant affinities of Eqmis asinus. Our observations are not 
arranged in a satistical form; nor have we occupied our time 
with minute variations in bulk, length, and capacity; we have 
selected those characters which are most striking and at the 
same time most instructive. 
Osteology. 
Vertebra, Cervical.—Atlas and Dentata : imperfect condition 
of foramina for spinal nerves, due to arrested development. 
Seventh vetebra prominens : vertebral foramen may occur in 
one or both transverse processes. 
Transverse process with costiforin prolongation. This con¬ 
dition is remarkable as showing a tendency to increase in the 
number of the ribs. The process is invariably autogenous, and 
not unfrequently sends a styloid prolongation downwards in the 
adult; but this is generally short, although we have seen it long 
and connected with the first rib below the upper head of scalenus 
by an elastic band; and in a specimen now before the transverse 
processes are asymmetrical, several inches in length, prolonged 
by well-marked elastic bands to cartilaginous nodules appended 
to the praesternum in front of the first sterno-costal articula¬ 
tions. 
Dorsal and lumbar. —The dorsal intervertebral gaps are 
sometimes truly intervertebral; often each is wholly pierced 
through the pedicle of one vertebra. The degree of separation 
of the costo-transverse articulation from that for the head of the 
rib varies much in the posterior dorsal vertebrae of different 
individuals. The last ribs also vary much in length, size, and 
degree of curvature. The presence of a so-called “ floating rib,” 
making the series nineteen in number, is frequently observable. 
This “floating rib ” is generally present only on one side. It is 
not a vertebral rib, but a sternal rib ; for it is appended to the 
extremity of one or two lumbar transverse processes, the homo- 
types of the vertebral costae of the dorsal region. Often, when 
not represented by bone, it occurs as a portion of cartilage or a 
band of white fibrous tissue, embedded in the abdominal mus¬ 
cles in such a manner as to remind us of the homotypical con¬ 
cordance of the intercostals and the abdominal muscles. 
In the sacral region it is often difficult to define the extent of 
the “ false sacrum ” backwards; for coccygeal vertebrae become 
appended by ankylosis, increasing apparently the ordinary 
number of five sacral bones. The last lumbar, too, sometimes 
