82 DISEASE IN WILD MAMMALS AND BIRDS 
the second, while one other lay in the arch of the aorta, 
the last in its descending thoracic portion. Those 
developing over the valves seem to arise from simple 
degenerative arteritis ; those that occupy the other loca- 
tions are apt to be surrounded by plaques on the intima. 
Aneurysms in birds reveal by microscopy some trace of 
all the vascular coats and seem not to construct an adven- 
titia from surrounding areolar tissue. The veins have 
presented no peculiar pathology, except in tumors which 
will be taken up later. A Derby 's Tyran showed a phle- 
bitis and periphlebitis of the left subclavian vein, of 
mycotic nature, which led to death by rupture 
and hemorrhage. 
