720 H. M. WOODCOCK. 



likely to be young forin.s ; these may, perliaps, themselves 

 undergo division, as in T. lewisi, and, moreover, in many 

 CMses, owing to a slow rate of growth and increase in size, 

 these small forms may give the impression of being distinct 

 parasites. On the other hand, very large, massive forms are 

 likely in many cases to be essentially multiplicative individuals. 

 Of course the possibility must not be overlooked that, in 

 some cases, large, stout forms may be sexual (female) indi- 

 viduals, but up to the present evidence pointing to the 

 occurrence of sharply differentiated sexual forms is only 

 forthcoming in a few instances. At any rate, so far as T. 

 f ringillinaruni is concerned, I think there is a general 

 parallel with T. lewisi in regard to the different types. 



In the case of many of the avian species so far described, 

 the account has been based in all probability upon the ordinary 

 adult type, e.g. T. avium, as emended by Laveran, T. 

 paddae, Tliiroux, etc. But in other cases, where only 

 stumpy forms have been desciibed, such as T. hannae, 

 another T. sp. from Senegambiau birds,^ and T. lave rani, 

 these probably do not represent the definitive type. Passing 

 on now to compare T. f ringillinaruni with certain other 

 trypanosomes, we may begin with the type-species, T. avium. 

 This name was originally given by Danilewsky, who followed 

 his own methods of nomenclature, to trypanosomes found 

 both in owls (sp. indet.) and in a roller-bird (Coracias 

 garrula)= Laveran (6) has rightly restricted this specific 

 name to a parasite from an owl (Syrnium aluco), which he 

 considers to be the same form as that observed by Danilewsky ; 

 the other trypanosome, from the roller-bird, is in all proba- 

 bility a different species. T. f ringillinarum, while 

 showing a general similarity in size and form with T. 

 avium, as described by Laveran, differs in two respects, 



' This parasite, described by Button and Todd (4). occurred in a 

 bird (Estrelda) in which the very different form T. johnstoni was 

 found. It is not at all improbable. I think, that T. johnstoni is the 

 ordinary form, and the broad, stumpy parasite a multiplicative fonn, 

 of one and the same species. 



