14 Mr. W. A. Forbes on the late Professor Garrod's 



culum, or may even completely blend. It is to a consider- 

 ation of the varying arrangements produced that this paper 

 of Prof. Garrod's is in the main dedicated ; and some of the 

 most important modifications may be noticed here. 



In a large number of birds the type presented by the com- 

 mon Fowl obtains. Here the flexor perforans supplies digits 

 ii-iv, and the flexor hallucis only digit i (the hallux) ; this^ 

 as it crosses the tendon of the flexor perforans, sends down 

 a strong fibrous vinculum {vide fig. 7 , V) . The proportions of 

 the vinculum to the main tendon (that distributed to the 

 hallux) vary greatly, as it may or may not be greater than 

 the hallucial portion. In some Birds of Prey a vinculum 

 may be combined with a special slip of tendon to digit ii^ 

 or it may be nearly entirely distributed to that digit. In 

 the Cathartidse a quite different arrangement, next to be 

 described, obtains. Here, and in many other birds, particu- 

 larly amongst the Anomalogonatce, the two tendons blend 

 completely, and the tendinous slip to the hallux comes off 

 from the blended tendon, apparently springing from the inner 

 side. A slight modification of this produces an arrangement 

 by which the hallucial slip seems to come off from the inner 

 side of the flexor perforans tendon in its upper part, before 

 it has been joined by the flexor hallucis. This last-named 

 condition obtains in such birds as Momotus, Merop)S, and 

 Dacelo. 



When the hallux is absent, as well as in Struthio (where 

 only two digits are present), the two tendons fuse completely 

 in the leg, and the compound tendon is distributed in the 

 usual way to the three (or two) digits. In many birds with a 

 hallux, when there is no long flexor to that digit, the slip to 

 it is extremely small ; and in some cases it is altogether absent. 

 In the Trogonidse, as might have been expected from the 

 well-known peculiarity of their feet, an equally peculiar 

 arrangement of the plantar tendons obtains (/. c. p. 345, 

 fig. 6). 



By far the most interesting feature, however, brought out 

 by Prof. Garrod's investigations into this subject, is the dis- 

 covery of the existence of two entirely different types of 

 plantar arrangement in the so-called " zygodactyle " birds, 



