1072 ON THE PERONEAL MUSCLES IN BIRDS. 



little intei-est in the peroneals. Some of the Colymbomorphs, 

 most of the Pelargomorphs, most of the Alectoromorphs, most 

 of the Cucviliformes, a few Coraciiformes, and most of the 

 Passeriformes would have to be placed together. We know from 

 other reasons that the association would be absurd, but it is not 

 more illogical than to place Omithorhynclvus and Echidna in the 

 same Order because they have retained a reptilian legacy that 

 was probably once the common property of all mammals. The 

 Ratites, some of the Colymbomorphs, some of the Pelargomorphs, 

 and a few of the Alectoromorphs would have to be placed to- 

 gether because of the absence of the brevis. Some of the 

 Colymbomorphs, and a few Pelargomoi'phs, a few Alectoromoi'phs, 

 a few Ouculiformes, most of the Coraciiformes, would similarly 

 have to be placed together because of their loss of the longus. A 

 rather tedious piece of work may be of some use, if only it serve 

 to direct attention to the confusion that mast arise if characters 

 be not carefully analysed before they are employed for systematic 

 purposes, and to the information which apparently unruly facts 

 may afford, if they are plotted out over a sufficiently compre- 

 hensive field. 



On the other hand, although the common i-etention and common 

 loss of ancestral character are no pi-oof of affinity, I myself, like 

 most anatomists who have taken an interest in trying to correlate 

 tlieir facts, have been impressed by the fashion in which allied 

 animals march along the path of modification in the same 

 direction. I have fovind this to be the case in Pigeons (Journ. 

 Linn. Soc, Zool. xxvii. p. 210), in Kingfishei\s (' Ibis,' 1901, p. 97), 

 in Gruiform birds (P. Z. S. 1901, p. 629), and in Limicoline birds 

 (P. Z. S. 1905, p. 155), and the general results which I have been 

 stating in this communication point in the same direction. It 

 appears to me therefore that the existence of notable unconformity 

 at least suggests that the position assigned in the System calls 

 for enquiry. 



The first notable instance is Pandion, which in the matter of 

 the peroneals differs from all the Eagles and Vultures and con- 

 forms with the Owls. I cannot find that this point in its 

 structure has been recorded previously, but many systematists 

 have seen in Pandion a link between the nocturnal and diurnal 

 birds of prey, and others have actually placed it amongst the 

 Owls. The question calls for re-examination. 



I am less impressed with the cases of Nyctidromus and Capri- 

 mukftis. So far as the longns is concerned they agree closely with 

 Podargus, but although the latter, like all other Coraciomorphine 

 birds, has a well-developed brevis, the two former have no brevis. 

 I have already pointed out that at the best the action of the 

 brevis is difficult to understand, and appears to be frequently 

 superfluous. I am therefore of the opinion that its loss in these 

 isolated cases, however curious, is insignificant. 



