1922.] H. A. Baylis and R. Daubney : Parasitic Nematodes. 265 



large proportion of this material was collected from animals, mostly Indian, in the 

 Zoological Garden, Calcutta. This applies to the majority of the species for which 

 no locality is given. 



It is difficult to judge to what extent the range of hosts of a parasite may be 

 affected by the presence of a number of suitable hosts in more or less close proximity 

 under artificial conditions in a menagerie. It has been observed that wild animals 

 tend to lose their original parasitic infections after a short time in captivity ; but 

 there are some indications in the present collection that a parasite hitherto only 

 known to occur in one or two hosts may, under these conditions, have been enabled 

 to extend its range to hosts with which it would not normally have come into 

 contact. As instances we may mention particularly the cases of Ascaris lumbricoides 

 and the various species of Heterakis, especially H. longecaudata ; while it seems 

 probable that the species of Ancylostoma, Belascaris and Toxascaris enjoy exceptional 

 opportunities in this respect in a menagerie where many kinds of carnivores are kept 

 near to each other. The lists of hosts that we have been able to compile for these 

 forms seem to bear out this suggestion. 



As regards the position of parasites in their hosts, there was a certain amount 

 of vagueness in many of the original labels. Often the label indicated the 

 " intestines," but this term appears to have been applied somewhat widely to 

 include most of the abdominal and thoracic viscera, and on this account we have 

 decided, in many cases, to omit any mention of the site of election. The species of 

 Heterakis from birds, for example, are usually found in the caeca of their hosts, and 

 to mention the " intestines " conveys no information of any value. 



The present report deals mainly with nematodes from vertebrate hosts, although 

 two forms found in invertebrates are described. The material submitted to us also 

 included a number of Mermithidae, but we have not attempted as yet to deal with 

 these, and have thought it advisable to publish without unnecessary delay the results 

 of our work on the more strictly parasitic forms. These include members of nearly 

 every superfamily, and, while the number of new species is not large, the collection 

 is valuable for the light it throws on a number of imperfectly known forms, and 

 for the general idea it furnishes of the parasitic nematode fauna of India. 



Throughout the report the names used for the hosts, so far as Indian animals 

 are concerned, are for the most part those given in the Fauna of British India 

 (Mammalia, by W. T. Blanford, 1888— 1891 ; Birds, Vols. I— II, by E. W. Oates, 

 1889— 1890, and Vols. Ill— IV, by W. T. Blanford, 1895— 1898 ; Reptilia and 

 Batrachia, by G. A. Boulenger, 1890; Fishes, by F. Day, 1889). The names of 

 hosts (other than domestic animals) which are not indigenous in the Indian Empire 

 are marked with an asterisk (*). 



