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NOTE ON TWO NEW FLAGELLATE PARASITES IN 
FLEAS— HERPETOM ON AS CTENOPH TH A LM I, IS. SP., 
AND GRITHIDIA H YSTRI CHOPS YLLA E, N. SP. 
By DORIS L. MACKINNON, B.Sc. 
Plate III. 
{From the Quick Laboratory, Cambridge.) 
There seems little reason to doubt that most blood-sucking in¬ 
vertebrates harbour in their digestive tract natural flagellate parasites, 
which have erroneously been described by various authors as part of the 
life-cycles of blood-parasites from vertebrates. Among arthropods such 
natural flagellates have now been observed in ticks, lice, bugs, mosquitoes, 
biting and nou-biting flies, and fleas; and the list of such hosts steadily 
grows. 
The following have been recorded from fleas : 
(1) Herpetomonas , sp., Balfour (1906) (= Crithidia pulicis, Wenyon 
(1908)), from Loemopsylla cleopatrae “ and possibly other species.” 
(2) Herpetomonas (?), Swingle (1907), from rat-fleas. 
(3) Crithidia, sp., Patton (1908), from the larvae of Ctenocephalus 
felis. 
(4) Crithidia ctenophthalmi, Patton and Strickland (1908), from 
Ctenophthalmus agyrtes. 
I propose to describe here two new intestinal flagellates from two 
species of fleas, Ctenophthalmus agyrtes and Hystrichopsylla talpae 
(or possibly C. bisoctodentatus) 1 . In naming them Herpetomonas cteno- 
phthalmi and Crithidia hystrichopsyllae respectively, I have been guided 
by the definition of these genera in a recent paper by Patton and' 
Strickland in this Journal. My thanks are due to Professor Nuttall 
1 
The Hon. N.C. Rothschild has kindly identified these fleas. 
