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presumed new species are, tire inure it is contesUible from the 
zoological standpoint. The cliaracters themselves must, first and 
foremost, be derived from the adult stages. ^^ilh regard to 
this point. Dr. SamBON’s evidence is nil. He has examined some 
badly preserved specimens, but the males showed no difference at all 
from those of Sch. hu-via/obiinii, and tlic females differed in the shape 
of the egg only. To this latter we shall return later; speaking of 
the adults, I may state, from a general point of view, that I would 
not, a priori, consider it as a serious objection to Dr. SamboN’s views 
if there really were no marked anatomical differences between the 
adults of the supposed two species. There are some few cases known in 
which certain forms resemble each other to such an extent that they 
might well be representatives of the same species, did not other 
factors-such as they are known to us at present seemingly exclude 
the possibility of the forms being the same thing. 
Dr, Sambon, in order to make the absence of all distinctive 
characters of his new species appear less weighty, dwells at some 
length on two cases in which, after a long and tedious comparison of 
many adult specimens, I have myself come to similar conclusions. It 
would lead me too far to discuss these cases in detail liere. I will only 
remark that one of them has no bearing on the case at present under 
discussion, inasmuch as the forms in question show differences 
which, though slight, are yet sufficiently pronounced to enable any 
expert to distinguish the respective forms as easily as he may 
distinguish Sch. hcevmtobium and Sch. bovis. In the second case, a 
parasite was found to inhabit several mammals, but to be entirely 
absent from birds, in Europe; whereas a similar form, in North 
Africa, could never be found in the same mammals, but was present 
ia birds which never visit Europe. In this case, I of course depend 
upon the facts available at present, and it is very probable that a 
comparison of a larger supply of new material (my own investigations 
were made 15 years ago) will reveal structural differences here also. 
But unless the difference be cleared up by new observations I feel 
compelled to consider the respective forms as different, in spite of 
iBeir apparent structural identity. However, Dr. Sambon, or any- 
else, is fully at liberty to show that the premises on which my 
opinion is based are erroneous. If he succeeds in showing this by 
irrefutable facts I shall certainly be the first to change my opinion. 
