74 W. N. F. WOODLAND 
of cleavage, the seales of adjacent longitudinal rows alternate 
with each other. (b) Underlying the skin is a layer of fat 
cells, thin dorsally, thick laterally, and extremely thin ventrally 
(Text-fig. 2, B). This subcutaneous fat layer of the 
tail is also divided into cylindrical segments by lines of cleavage 
continuous with those of the skin; on their internal surface 
the fat cells are bounded by a thin dense layer of connective 
tissue. ‘T'ext-fig. 38, K represents the fat layer which has been 
cut through in the mid-dorsal line and flattened out. The 
extreme thickness of the two laterally-situated regions is well 
shown. (c) Lying internally to the subcutaneous fat layer is 
a layer of muscles, the caudal flexor museles, the 
attachments of which will be described later. The laterally- 
situated flexor muscles are the thickest, as might be expected. 
On their external surfaces these muscles abut against the dense 
connective tissue lining of the subcutaneous fat layer, and on 
their internal surfaces they are for the most part attached to 
the outer surfaces of the submuscular fat bands. (d) Lying 
internally to the layer of caudal flexor muscles are the s u b- 
muscular fat bands. These thick bands are four m 
number, two on each side of the vertebral column, and on each 
side one lying dorsally to the transverse process of the vertebra 
and the other ventrally. These fat bands are, like the sub- 
cutaneous fat layer, chiefly composed of fat cells, and are 
segmented by lines or rather planes of cleavage continuous 
with those already mentioned. The four fat bands are traversed 
by eight longitudinal radiating connective tissue septa (one 
dorsal, one ventral, two lateral, and four in between these), 
which unite the dense connective tissue layer liming the ternal 
surface of the fat layer with the thin layer of connective tissue 
investing the vertebral column. These and minor septa 
(shown in T'ext-fig. 8, J, im which the fat layer has been cut 
through along eight lines, and the muscles and skin removed) 
separate the individual musele processes from each other and 
serve to some extent for the attachment of the muscles. 
(e) Internally to the submuscular fat bands and forming the 
axis of the tail is the caudal vertebral column. 
