446 WwW. A. HASWELL. 
Gardiner (10) states that he has frequently seen one speci- 
men of Polycherus caudatus pursuing and trying to get 
on the back of another, which showed symptoms of restless- 
ness and discomfort, and endeavoured to escape. Under the 
dorsal integument of the second individual, in such a case, 
were found numerous spermatozoa, and in the vicinity abra- 
sions were observed. From these facts he concludes that we 
have here an example of hypodermic impregnation, and that 
the function of the chitinous mouth-pieces is to bring about 
this result. 
This appears to me not to be a tenable view of the function 
of the parts. There is no direct evidence that the burs are 
capable of being everted in such a way as to be brought into 
play as organs for effecting hypodermic impregnation, and it 
appears very improbable, from their structure, that they are 
capable of being so used. Moreover, such a theory involves 
a supposition which bears great improbability on its face. 
We should have to suppose that in these animals we have a 
process of fertilisation without parallel in the animal kingdom 
—a process in which one individual, having received into a 
part of its female apparatus a mass of spermatozoa from 
another, uses them to impregnate a third! 
The conclusions to which I have come with regard to the 
functions of these parts have already been partly indicated. 
The observation of the passage of a stream of spermatozoa 
from the apex of the mouth-pieces into the tissues in the 
near neighbourhood of the mature ova (previously also 
recorded by Repiachoff [23] with reference to another 
member of the group) seems to prove the function of the 
bursee to be the internal fertilisation, one by one, of the ova 
as they become mature. ‘The structure of the parts seems to 
render it unlikely that the spermatozoa so utilised can be 
derived from the same individual, so that a process of copula- 
tion, though not actually observed, most probably occurs. 
This may take place, not through the ventral female aperture, 
but through the dorsal passage (Laurer’s canal) the existence 
of which is otherwise not easy of explanation, and, if so, 
