78 M. O. Strobelt on the Anatomy and 



be not uninteresting, and indeed of great importance, with 

 respect to the opinions of Lamarck and Darwin, to ascertain 

 more precisely the regions of distribution of the two species 

 and their boundaries. Thus, in Darwin's great work on 

 the Descent of Man, he says* : — u In determining whether 

 the varieties of the same kind of domestic animal should 

 be ranked as specifically distinct, that is, whether any of 

 them are descended from distinct wild species, every natu- 

 ralist would lay much stress on the fact, if established, of 

 their external parasites being specifically distinct. All the 

 more stress would be laid on this fact, as it would be an ex- 

 ceptional one; for I am informed by Mr. Denny that the 

 different kinds of dogs, fowls, and pigeons, in England are 

 infested by the same species of Pediculi or Lice." 



A. Murray (22) has investigated the Pediculina collected 

 in different countries from the different races of men, and 

 found considerable differences both in their colour and in the 

 structure of the buccal organs and limbs. How much more 

 important would it be if it were found that different species 

 occur upon different races. We know, indeed, only that 

 different lice are parasitic upon cattle &c; but in collecting these 

 no one has yet taken the trouble to note the race of the host 

 in each case. It is only when this has been done in numerous 

 cases that fertile conclusions may be drawn from these obser- 

 vations. 



After this digression, let us go back to Piaget. He says 

 further (p. 650), " Gurlt figures two species as very distinct, 

 especially in the form of the head, and in the transverse spot 

 of the penultimate segment j but he nowhere gives the sexual 

 differences, which would be decisive." 



That Gurlt 1 s figures (11) are very different is easily seen ; 

 but they have been drawn so much in miniature that we 

 cannot get very much more out of them. And as regards 

 the non-statement of sexual differences, we need not wonder 

 at this in Gurlt's case ; for we do not find such differences 

 noted even by Denny, from whom Gurlt generally translates 

 pretty literally. 



From what has been said it would appear that Piaget had 

 no grounds for casting doubt upon the existence or the specific 

 distinctness of Hcematopinus tenuirostris. That we have 

 really to do here with two perfectly different species is suffi- 

 ciently shown by my figures (1, 2) on Plate III., which I have 

 made from individuals lying before me ; and in connexion | 



with this it must be particularly noticed that I possess males 

 and females of both species. I 



* Vol. i. p. 219. 



