498 
DE. PETTIGEEW ON THE AKBAN GEMENT OF THE FIBEES 
A A', diagram 4. Lines winding in a spiral nearly vertical direction from 
above downwards, and forming the first layer (Plate XII. fig. 1, com- 
pare with the fibres marked ff' and d d’). These lines are continuous 
at the base and the apex with the lines forming the seventh or corre- 
sponding internal layer E E' (Plate XII. fig. 8, compare with the fibres 
marked o and n). 
B B', diagram 5. Lines winding in a spiral oblique direction from above down- 
wards, and forming the second layer (Plate XII. fig. 2, compare with the 
fibres marked fd 1 ). These lines are continuous at the apex and the 
base with the lines forming the sixth or corresponding internal layer D D' 
(Plate XII. fig. 6, compare with the fibres marked on), 
B B', diagram 4. Lines winding in a spiral very oblique direction from above 
downwards, and forming the third layer (Plate XII. fig. 3, compare with 
the fibres marked /V). These lines are continuous at the apex and 
the base with the lines forming the fifth or corresponding internal layer 
D D' (Plate XII. fig. 5, compare with the fibres marked o n ). 
C C' C", diagram 5. Lines winding in a circular or transverse direction and 
forming the fourth or central layer, which divides the three external 
from the three internal layers (Plate XII. fig. 4, compare with the fibres 
marked fd 1 ). It is in this layer that the three external layers terminate, 
and the three internal ones (diagram 6, DE E') begin. 
Diagram 6. A cone similar to that figured at diagram 4, with the external layers uncoiled. 
Shows the fourth, central or transverse layer, and the three internal layers. 
See pages 484, 485, & 486. 
Diagram 7. Symmetrical cone produced by the rolling of portions of two sheets within 
each other. Shows the double entrance of the lines at the apex, and how 
closely the position and shape of the musculi papillares may be imitated. The 
interior of this cone is seen at diagram 11, and should be compared (Plate 
XII.) with the interior of fig. 13. See pages 486 & 487. 
AB. Portion of posterior sheet, the lines composing which enter the apex 
anteriorly at E, to represent the posterior musculus papillaris X (Plate 
XII. fig. 14, compare with y). See pages 486 & 487. 
C D. Portion of anterior sheet, the lines composing which enter the apex 
posteriorly at F, to represent the anterior musculus papillaris Y (Plate 
XII. fig. 14, compare with x). See pages 486 Sc 487. 
Diagram 8. Symmetrical cone produced by the rolling of two sheets of net within each 
other, similar to those figured at Plate XY. diagram 2. Shows the position 
and track of the anterior papillary muscle (Y). See pages 486 & 487. 
Diagram 9. Interior of a single sheet of net rolled up as explained. Shows how the 
spiral almost vertical direction pursued by the anterior musculus papillaris 
(Y) may be imitated (Plate XII. fig. 13, compare with y). See page 484. 
