370 



DR. E. W. SHIJFELDT's MOEPHOLOaiC AL 



of his dissection of tbe parts in question, and it may be seen in 

 figure 1, plate xxiv. of liis ' Collected Scientific Memoirs.' 



With the exception of leaving ofi" the lower extensor of the 

 forearm, his drawing is correct, and from it we see that the 

 tensor patagii longus arises and is inserted pretty much as we 

 find it in most birds ; but with respect to the tensor pataqii 

 hrevis a very marked departure is met with, for that muscle is 

 as prominent as any other in the arm, more so than the majority 

 of them. It may be said to be somewhat pear-shaped in form, 

 with its larger end at the origin at the shoulder, while the smaller 

 extremity becomes attached to a tendon which passes directly 

 over the upper surface of the extensor metacarpi radialis longior, 

 longitudinally. 



This tendon arises at the outer condyle of the humerus, and 

 passes to the carpus for insertion, and is very well shown in 

 Garrod's drawing of Patagooia. 



I find it present in all the Trocliili, where, so far as I know, 

 it constitutes a unique method of insertion for the tensor patagii 

 hrevis, and to make it clearer I present a drawing of it for 

 Trochilus platycercus (PI. XXII. fig. 28). 



Since Garrod saw so clearly this very unusual insertion of the 

 tensor patagii hrevis in the Humming-birds, I am surprised 

 beyond measure that be did not at once make careful comparisons 

 with the Cypseli in this particular ; had he done so, he would 

 have found, as I have, that the mode of insertion of this muscle 

 in those birds is entirely different. In the first place the body 

 of the muscle is comparatively much smaller ; it is also of a very 

 diff'erent form, being oblong and not pear-shaped ; finally it is not 

 inserted into any special tendon, but directly upon a tendinous 

 fascia on the surface of the extensor metacarpi radialis longior, 

 and its fibres, becoming slightly tendinous, run down with that 

 muscle for insertion at the external condyle of the humerus. 

 In PI. XXII. fig. 29, I present a drawing made directly 

 from my dissection of these parts in a specimen of Chcetura 

 pelagica. 



As both the Humming-birds and Swifts have short humeri 

 (though "shortness" is not a character, I believe) and have 

 developed a large tensor patagii hrevis (though "size" is not a 

 character either, I believe) it might not unnaturally be expected 

 that they should have this particular muscle s}i07^t and tJiich ; 

 but when we come to examine the true morphology, how vastly 



