80 W. N. F. WOODLAND 
jecting transverse processes of the vertebra. I have labelled 
each of the anterior muscle processes and their posterior 
extremities in order that the muscle masses shown in the 
figure of the transverse section of a segment (Text-fig. 2, B) 
may be compared with those of Text-fig. 8, A, C, D, H, F. 
In short, dissection and serial sections show that all the pos- 
terior continuations of the eight anterior muscle processes are 
firmly attached posteriorly to the vertebral 
axis, directly dorsally and ventrally to the neural and haemal 
spines respectively, and laterally to the transverse processes, 
and indirectly by connexion with the eight radiating septa of 
connective tissue which join the connective tissue internal 
lining of the fat layer with the connective tissue external 
investment of the vertebrae—these traversing the area of the 
fat bands. The muscles are also firmly attached on their 
inner surfaces to the fat bands (Text-fig. 3, G), which them- 
selves are firmly connected with the connective tissue invest- 
ment of the vertebrae. The eight anterior muscle processes, 
on the other hand, are only feebly attached to the septa 
separating successive muscle segments. Usually the tail of 
a Gecko merely depends from the body, but when the animal 
is excited (as when pursuing a fly) the tail can be slowly flexed 
from side to side. During these lateral flexions of the tail the 
muscles of many segments on one side of the tail contract and 
the strains on the slender anterior attachments of the muscles 
are relatively slight, however violent the flexion (as when the 
-animal is being chloroformed), because the muscles of many 
segments are involved, i.e. the effect is distributed between 
them and the tail is freely movable. On the other hand, when 
the tail is seized by another Gecko, the part of the tail seized 
is relatively fixed, and since the body is also fixed in position, 
and the muscular contraction involved in autotomy is limited 
to one segment (see Statement 2) and is therefore proportion- 
ately violent, the contraction of the muscle, in trymg to flex 
relatively inflexible segments, i.e. in trying to cause to approach 
each other the sides of two adjacent segments which, under the 
conditions, can only approach to a very small extent, is then 
