CORRESPONDENCE. 



I 



The Bird's Foot. 



I FEAR, from the courteous criticism of Mr. Mitchell in the September 

 number of Natural Science, that I did not express myself clearly in my note on 

 " The Bird's Foot," but if he will take the trouble to look over the article again, I 

 think he will find that my intention was not to controvert Mr. Finn's proposition, 

 but rather to maintain it. My conclusion in regard to the arrangement of the 

 tendons was simply that the three-toed birds must have lost their fourth toe before 

 its tendon became differentiated from the others, and this, it seems to me, is quite 

 different from saying that birds " do not show evidence of the modification of their 

 foot from a specialised four-toed foot." 



If the deep flexors of a four-toed foot were entirely free from one another — 

 as in the Passeres— and that bird were to lose the inner toe from disuse, would not 

 the tendon of the flexor longus ballucis become aborted also for lack of something 

 to pull upon ? I think it would, but unfortunately we have no passerine or 

 liummer minus a hind toe to settle the question. As to the distinctness of the 

 muscles of the flexor perforans digitorum and flexor longus hallucis, if deductive 

 reasoning is worth anything, we are justified in saying that these muscles are com- 

 pletely differentiated before the tendons, since all the more generalised birds are 

 synpelmous while the flexor muscles are quite distinct. 



In Pterocles and Chauna — there should, by the way, have been a query after the 

 words Palamedea also, because I v;as not acquainted with its foot — it is to be noted 

 that while the slip to the first digit is lacking, the flexor longus hallucis still meets 

 with resistance from its vincular connection with the other tendons, and is thereby 

 probably prevented from becoming abortive. Is there not a reason, based on habit, 

 why Palamedea still retains the slip to the first digit ? If I remember aright Palamedea 

 is a bird of the forest region, and Chauna more a resident of the pampas, and does 

 not Palamedea sometimes perch ? 



Turning now to the question of flight, while I cheerfully subscribe to the pro- 

 position that birds which fly well to start with will gain increased power of flight by 

 ability to rest on the surface of the water, I protest that this does not furnish 

 evidence that flying birds are ever derived from those which splash along the surface. 

 In this connection it would be unfair not to speak of the habits of young ducks, 

 suggestively named flappers by English writers on field sports, and not to mention 

 the little Hoactzin which swims and dives well, although it does not, so far as I am 

 .aware, pass through any splashing stage. On the other hand, the difficulty ex- 

 perienced by the majority of the ducks in rising from the water in a calm, or down 

 wind, is a most powerful argument against flight having been acquired in this manner. 

 Right here let me say that Mr. Finn's suggestion in the foot-note on p. 211 seems 

 extremely good. I am quite ready to believe that flight originated by jumping down, 

 but not by jumping j^/. It should be remembered that the pluvialine relatives of 

 the Gull fly remarkably well, and that the Gull is but an indifferent swimmer, gathering 

 its food along the shore or at the surface of the water, not beneath it. The broad- 

 winged Pelicans, too, are surface swimmers, not very good ones either, and sit high 

 upon the water like the Caravels of old, instead of ploughing through it after the 

 manner of a torpedo boat, as do their relatives the Cormorants and Snake Birds. In 



