3 



bird (P. Z. G. Lab., 823); and Lophorlyx calif ornicus, one 

 bird (P. Z. G. Lab., 997). Recently, but not included in the 

 present series, several of the pigeon family have also been 

 found similarly infested. 



From the very serious alterations found in the ]>n>ventricle 

 there can be no doubt of the serious importance of these 

 parasites to the host, which unquestionably may by a serious 

 grade of infestment be killed by the worms. In their earlier 

 studies of the matter the writers searched, but in vain, for 

 the presence of larva* in the blood on the supposition that the 

 parasites were true h'laria-; but later determined the fact that 

 the larva-laden ova are passed through the alimentary canal 

 and are to be found in numbers in the fecal discharges. 

 Search for an intermediate host has thus far been unavailing, 

 the roaches, mice, and rats in the bird house having been 

 repeatedly examined without success. Tentatively, therefore, 

 the idea has been adopted that the ova with their enclosed 

 larva?, protected by the thick and firm walls of the eggs, are 

 mechanically distributed, as by air currents, with dust from 

 one cage to another, and in this manner get into the food or 

 water of each bird and are swallowed therewith and develop 

 from the egg within the mouth, esophagus, or proventricle 

 of the new host. Based upon this view, it has been urged to 

 the keepers of the collection that the cages are to be kept 

 scrupulously clean, and, after the death of a bird or its 

 transference, that the cages be sterilized. Apparently under 

 such precautions there is some diminution of the occur- 

 rence of the parasites; but the interval has been too brief to 

 permit certainty in this direction at the present time. 



The structural characteristics of the worms are constant; 

 but there is considerable variation in size of the mature speci- 

 mens as obtained from different hosts, and often among the 

 examples obtained from a single bird. The average maxi- 

 mum length of fully developed females was a little over 14 mm. ; 

 thickness, 0.45 mm.; average maximum length of males. 

 8 mm.; thickness, 0.31 mm. The smallest adults were 



