1056 DR. p. CHALMERS MITCHELL ON THE 



proximal portion of the fibula and then forms a very long tendon 

 which runs down the leg parallel with the tendon of the longus, 

 dips under the slip to III, and has the usual flattened insertion. 



Alcidse. Alca torcla. — The P. longus is fairly large, with super- 

 ficial and fascial origins, then a long tendon which gives off a 

 broad anchor and ends as the normal slip to III. The P. brevis 

 is also rather strong but much inferior to the longus. It has an 

 extensive origin from the fibula and then passes into the usual 

 tendon with normal insertion. 



Pterocles. Pterocles cdchata (2 examples). — The P. longus 

 is broad and rather strong, with all three origins and broad 

 anchor and slip to III. The P. brevis is absent, so that in this 

 respect the Sand-Grouse agree with the general tendency of the 

 plover-like birds and differ from the game-birds. 



C o 1 u m b fe . Starnmnas cycinocepliala. Leiicosarcia jiiccda 

 (2 examples). Phlogcenas crxientata and P. luzonica. Geoj^haps 

 plumifera. Pliaps chalcoptera and P. elegans. Cohmibula picui. 

 Geopelia cuneata and G. tranquilla. Zenaidura carolinensis. 

 Carpop>haga rufigula. Columba livia (many examples, wild and 

 domestic). Osmotreron bicincta (2 examples). 



The Doves and Pigeons present an interesting series of modifi- 

 cations. A state of affairs very closely resembling what occurs 

 in Limicolous birds is not infrequent. In Leucosarcia, for 

 instance, the P. longus is very strong, with good superficial and 

 fascial origins and a considerable deep origin from the proximal 

 portion of the fibula. The muscular mass narrows to a very long 

 tendon, which eventually gives ofi' a broad anchor and runs on 

 to form a good slip to III. The P. brevis similarly arises chiefly 

 from the proximal portion of the fibula and the adjacent surface 

 of the tibia, passes into a long tendon which after traversing a 

 fibrous bridge flattens out to the usual insertion. The P. longus 

 is definitely the dominant muscle, but the brevis is well formed 

 and functional. In Cohimha the conditions are similar, but the 

 extent of the fibular or deep origin of the longus varies, and the 

 length of the tendon varies inversely with it. In Carpophaga 

 the fibular oi-igin of the longus is still more important, and in 

 many of the smaller Pigeons and Doves, and in Osmotreron^ the 

 deep origin is the more important, the superficial and fascial 

 origins getting weaker ; the tendon is shorter, but the whole 

 muscle is relatively feebler. So also in the smaller Doves and 

 Pigeons, the P. brevis tends to degenerate, arising only from the 

 lower end of the fibula and the tibia distad of this, so that the 

 tendon is very short and very different from the typical Limicoline 

 condition. On the other hand, in Osviotreron^ the P. longus has 

 become smaller and reduced to its deep origin with a i^elatively 

 short tendon, but the P. brevis has increased in size and is 

 actually stronger than the longus. 



In Charadriiform birds generally the P. longus is the dominant 

 muscle and the P. brevis tends to become weaker or to disa.ppear. 



