Physiology o/'Hsematopinus tenuirostris, Burm. 77 



tive as they may be, we at once see that we have to do with 

 two separate species. Leaving all other characters out of 

 consideration, this is shown at the first glance by the great 

 difference of the head and thorax in the case of both authors*. 



But however different the male and female of H. eury- 

 sternus may be, we find, if we compare the two species [H. 

 eurysternus and H. tenuirostris) } even without magnifying, 

 that they are typically distinct, and that there can be no ground 

 for the assumption that we have to do with the male and 

 female of the same animal. 



Piaget takes as a further ground for doubt Denny's state- 

 ment that he had only seen two individuals of this species, 

 which were obtained from a calf, whilst Giebel asserts that 

 the species lives very commonly upon the domestic ox and is 

 very widely distributed. Denny saysf : — u The only two ex- 

 amples of this species which I have examined were kindly 

 forwarded to me by Rev. L. Jenyns, who found them upon 

 a calf. Mr, J. named them vituli\ and I have no doubt they 

 are the species so named by Linnaeus and Fabricius. It 

 may appear somewhat strange that a young animal should 

 have a distinct species of parasite which is not found upon its 

 parents ; but, as far as we are able to judge, such is the fact. 

 I have examined numbers of the lice from oxen, but never 

 detected a single specimen of this species amongst them, 

 though there were of Trichodectes scalaris, which lives upon 

 cattle and in society with the H. eurysternus. 17 Notwithstand- 

 ing his endeavours, therefore, he could never find the species 

 upon Bos taurus. Giebel, on the contrary, says it is very 

 common and widely distributed. Piaget stumbles over this 

 apparent contradiction ; and yet both statements may very well 

 be true. 



1 have not been much more fortunate than Denny. I have 

 only once found II. tenuirostris upon an ox, which came 

 from Hamburg ; but in this case it was in great numbers. 

 Subsequently I have never succeeded in procuring this species 

 in the neighbourhood of Minister, but always obtained only 

 //. eurysternus and Trichodectes scalar is. This circumstance 

 may be explained in two ways: either H. tenuirostris is 

 parasitic upon our Bos taurus, and we have only not found it 

 hitherto, or the animal is confined to a particular district 

 and perhaps to a particular race. Nitzsch and Giebel obtained 

 their lice from the environs of Halle, while Denny collected in 

 England, and Piaget in Holland. Unfortunately we have no 

 precise observations upon either species. It would certainly 



* See Denny, pi. xxt. figs. 5 & 3 ; and Giebel, Taf. ii. figs. 8 & 9. 

 t Loc. cit. p. 32. 



