W. S. Patton 
125 
knowledge to speculate further. When we know more of the life 
histories of the trypanosomes and especially of such forms as have 
recently been described from snakes and from the two-toed sloth, we 
may be in a position to formulate a more definite hypothesis regarding 
the phylogeny of the Haemoflagellates. Before leaving this subject 
however we wish to emphasize the fact that the present Herpetomonas, 
Crithidia and Trypanosoma are distinct forms, and that as far as we 
know one does not become converted into the other. Because a 
trypanosome may exhibit certain stages in its development like a 
Crithidia, we are not justified in calling it a true Crithidia and vice 
versa ; exactly the same may be said regarding Herpetomonas and 
Trypanosoma. 
The eighth section of Woodcock’s article is devoted to the systematic 
consideration of the Haemoflagellates; here we find that he divides the 
sub-order Monodina into the single family Trypanomorphidae. We 
have shown above that the genus Trypanomorpha is almost certainly 
Crithidia fasciculata of Leger, so that this new genus can hardly be 
retained. Woodcock divides the sub-order Heteromastigina into one 
family in which he places the genera Trypanoplasma, Trypanophis 
and Trypanosoma ; we are left in doubt as to where the important 
genera Herpetomonas and Crithidia come into this classification as no 
mention is made of them here. 
We have pointed out above that the orientation of the body, and 
the biological features associated therewith, which Woodcock has used 
as important diagnostic characters in support of his classification, are 
very faulty, and that therefore this grouping of these flagellates is open 
to criticism. In the present state of our knowledge, it would have been 
wiser to have refrained from making new families, and genera, and to 
have been contented with a much simpler and more natural classifica¬ 
tion. We would prefer to group the Haemoflagellates and allied forms 
as follows: 
Class 
MASTIGOPHORA. 
Sub-class 
LISSOFLAGELLATA. 
Order 
MONODIDEA. 
Sub-order 
Monodina. 
Family 
Trypanosomatidae. 
Genus 
Trypanosoma. 
» 
Trypanoplasma. 
Crithidia. 
)> 
Endotrypanum. 
>> 
Herpetomonas. 
