Vol. xxxvi.] 52 



Albatrosses rather than tlie Shearwaters, and the linking of 

 Ossifraga to the Albatrosses^ not the Fulmars. 



This illustration, prepared specially for this Discussion, 

 ■will show that there is something in the idea propounded. 

 The Mallophaga require to be much more assiduously 

 collected and studied before more general statements can be 

 made, and it is hoped that ornithologists, when collecting 

 specimens, will pay some attention to the preservation of 

 these minute parasites, especially in the case of rare birds 

 and those of doubtful affinities. 



Mr. Bruce Cummings (Entomological Department, British. 

 Museum) followed with a paper, of which the following is a 

 resume : — 



" Probably no one more than Mr. Harrison himself would 

 insist on the care with which this phylogenetic test should 

 be applied. Two important factors must be borne in mind: 

 convergence and the chance straggling of the parasites on 

 to other hosts. For example, is the Gallinaceous parasite 

 on Penguins really Gallinaceous, or has it had an indepen- 

 dent origin and merely converged on the Gallinaceous genus 

 Goniodes? Convergence, I have reason to believe, is not 

 unknown in this group of insects. With regard to that other 

 cause of stumbling — straggling, — the Hoatzin presents us 

 with a case in point. Mr. Harrison has referred to the 

 undoubted Gallinaceous affinities of this bird, supported by 

 the existence of a Gallinaceous parasite upon it. But 

 Opisthocomus possesses also a LcEmobothrium^ an isolated 

 genus, distinguished by the relatively enormous proportions 

 of the individual species. It is, par excellence, the parasite 

 of the Birds-of-Prey, but occurs also on Psuphia, Fulica, 

 Ibis, Anser ; so that there is a tangle here in which the 

 simple phylogenetic relationship between parasite and host 

 does not hold good. To clear it up, we must assume either 

 a Gruiform or Ciconiif orm origin of the Birds-of-Prey ; we 

 must suppose that the genus L(Bmobothrium has remained 

 quite stationary in its evolution from the time when the 

 Birds-of-Prey took their origin, and we must explain the 

 occurrence of the parasite on all the remaining birds as 



