61 



of mucus and fond occupying the proventrii !(, were commonly 

 found with tin- head end emlicdded in the more or less dis- 

 integrated lining membrane of (lie proventriele; the resulting 

 mass often completely obslrucling the lnl>c and preventing 

 the passage of food. The parasito varied much in the nuni- 

 IHT found in each liird, the smallest number in the series being 

 two in a valley <|iiail, and tlie largest one hundred and thirty- 

 four in a Hosehill parrakeet; commonly the grade of infest- 

 ment was represented In twenty to forty worms; and generally 

 the females outnumbered the males by alxnit three or four 

 or more to one. As a rule, in the case of infestment by larval 

 or immature worms the nuintar of parasites found ranged 

 high, nearly a hundred or more than a hundred; from which 

 it is suggested that ordinarily in the course of parasitism a 

 number of the worms are dislodged from the proventriele, 

 passed through the host's intestine and discharged. There 

 is no evidence leading to the supposition that the adult 

 parasites may locally produce the young forms; and in the few 

 instances in which larval and partially developed or mature 

 forms were encountered together the probability is that there 

 took place repeated infestment. Six of the birds were in- 

 fested by larval worms. One of these showed both larva* 

 and fully developed anil gravid adults, the rest either larvn? 

 alone or larvae and immature adult forms. AH of the latter 

 birds were relatively recent admissions to the Gardens at time 

 of death, having been in the collection from one or two to six 

 or eight weeks. The one host having both gravid adult worms 

 and larvae had been in the collection over a year prior to its 

 death; and, with the exception of three birds mentioned 

 below as possibly introducing the parasites into the collection. 

 the hosts were all inhabitants of the Gardens for several 

 months to several years. From this it is suggested that the 

 period required from the development from the egg to the 

 mature adult stage is somewhere within six or eighl weeks. 



There is no positive information as to the time when first 

 the parasites appeared in the collection; and their source 



