648 DISEASE IN WILD MAMMALS AND BIRDS 
At the London Gardens (33) acariasis was found in 
forty-four young rhesuses dying of pneumonia, and the 
observers ascribed the inflammation to irritation of cer- 
tain doubly refractile crystals which occurred in the 
excreta of the mite. There are four other recorded 
instances of such disease in monkeys, all caused by dif- 
ferent species of parasites. 
As to pathogenesis of these arachnids, the London 
experience is most illuminating in that it was young 
rhesuses that were affected. Our specimens were mature, 
and nothing was stated to the contrary in the other 
reported cases from various parts of the world. The 
parasites are perhaps inhaled from the straw used as 
bedding, since such vegetable material is a common 
habitat for mites. If the resultant acute pneumonia is 
weathered the relics might remain only in the form of 
the subpleural and parabronchial cysts such as we have 
seen at the Philadelphia Garden. 
I am the more willing to accept the possibility that the 
simian arachnids can induce an acute pneumonia after 
studying a very definite case of bronchopneumonia in a 
prairie dog, which was induced by Cytoleichus penrosei 
Weidman 1916.(34) 
Periproventricular FiLARroiE OF Birds, — Every year 
we report a number of cases (up to twenty-three) of these 
woniis, probably several species, coiled under the serosa 
of the air sacs and most commonly around the proven- 
tricle. Tentatively we have recognized two forms, a 
shorter (an inch or so long) and a longer (three to four 
inches). The latter is most inextricably coiled, but the 
former may be teased out. Microfilaria occur in the blood 
of the latter cases, but not in that of the former. The 
adults have been observed to penetrate from their posi- 
tion in the air sac serosa into the lumen of the proventricle 
(goose), to have caused rupture of the inferior cava 
(33) Proc. Zool. Soc. Lvndon, 1919, p. 14. 
(34) Jour. Parasit., Dec, 1916, V. 3, pp. 82-89. 
