496 
DE. PETTIGREW ON THE AEEAN G-EMENT OE THE FIBRES 
the anterior coronary artery (o o), with fibres having a similar direction 
on the septum ( l ) by simply bending upon themselves. 
n. Fibres of the septum passing from above downwards to become continuous 
in the track for the anterior coronary artery (pp) with the external 
fibres of the left ventricle ( m ), these fibres winding in a spiral direction 
from above downwards to enter the left apex, not by simply bending 
upon themselves, but by twisting rapidly round in a whorl. 
Fig. 46. Base of the ventricles of the heifer’s heart, as seen from above, posteriorly. 
Shows the relative position and shape of the auriculo-ventricular openings 
and the orifices of the large blood-vessels. It also shows how the external 
fibres curve out of the former all round. See pages 454, 470, 472, 473, 
& 483. 
Fig. 47. Bight and left ventricles of the heifer’s heart laid open, seen posteriorly. 
Shows the position and shape of the musculi papillares and carne® column®. 
See pages 460, 461, 469, & 470. 
Fig. 48. Left ventricle of the heart of the American elk, inverted. Shows the complete 
absence of car lie® column®, and the undeveloped condition of the musculi 
papillares. See page 461. 
Fig. 49. Transverse section of the right and left ventricles of the deer’s heart, half an 
inch from the base. Shows the shape of portions of the right and left ventri- 
cular cavities, and how the right ventricular cavity curves round, or is applied 
to the left. See pages 480 & 481. 
Fig. 50. Transverse section of the right and left ventricles of the deer’s heart, rather 
less than an inch and a half from the base. Shows the same as last sec- 
tion, and in addition how the fibres of the right ventricle dip in at the ante- 
rior coronary groove ( m ) to become continuous with fibres having a similar 
direction on the septum ( e '). See page 481. 
Fig. 51. Transverse sections of the right and left ventricles of the deer’s heart, two 
and a half inches from the base. Shows the same as the two preceding 
sections. See pages 481 & 482. 
Fig. 52. Transverse section of the left ventricle of the deer’s heart, three and a half 
inches from the base, and fully half an inch from the apex. See page 482. 
Fig. 53. Transverse section of the left ventricle of the deer’s heart, a quarter of an 
inch from the apex. See page 482. 
Fig. 54. Left ventricle of the sheep’s heart, seen posteriorly. Shows how the fibres 
composing the inner half of the central layer of the left ventricle (f) pass 
through the septum ( g ). See page 478. 
Diagram 1, Plate XV. Sheet of net with threads of wool drawn through it at intervals 
to represent the fibres, laid out lengthwise or across the body. Shows how by 
folding in a portion of the sheet (B C) and rolling it obliquely upon itself in 
the direction of the arrow marked E, until three and a half turns have been 
