LEPIDOSIREN PARADOXA. 
53 
The Development of the Heart and Vascular 
System of Lepidosiren paradoxa. 
By 
Jane I. Robertson, M.B., 
Carnegie Research Scholar, Glasgow University. 
With Plate 5 and 31 Text-figs. 
Contents. 
PAGE 
I. Introduction . . . . .53 
II. Summary of General Features of the Vascular 
System of Lepidosiren . . . .55 
(a) Heart . . . . .58 
(b) Arteries . . . . .68 
(c) Veins . . . . .72 
III. Development of the Heart . . .76 
IV. Development of the Arteries . . . 105 
V. Development of the Veins . . . Ill 
VI. Origin of Vessel- and Blood-Cells . . 123 
VII. Description of Plate .... 131 
I. Introduction. 
In the following account of the development of the heart 
and blood-vessels of Lepidosiren paradoxa I have endea- 
voured to trace their main morphological rather than their 
minute anatomical relations. I trust that few points of im- 
portance have been neglected, though probably many minutiae 
of interest have been passed over. 
