342 MR. A. H. GARROD ON THE DEEP [Apr. 20, 
metatarse the feror longus hallucis sends downwards a fibrous vin- 
culum (V) which joins the flecor perfurans digitorum tendon just 
before it commences to trifurcate. In all cases this vinculum is 
always directed downwards from the hallux-muscle to the digits- 
muscle, so that, when the tendon of the flewor perforans digitcrum 
alone is pulled upon, the three anterior digits alone are flexed ; but 
when the flexor longus hallucis is put in action, the digits as well as 
the hallux are simultaneously flexed. 
The proportion borne by this vinculum to the main tendon of the 
flexor longus hallucis varies considerably. In some birds it is com- 
Fig. 3. Fig. 4. 
Tinnunculus alaudarius. Buceros rhinoceros, 
paratively feeble and insignificant ; whilst in others, with but a small 
hallux, it is much larger than the hallucial moiety, and seems to be 
the main continuation outwards of the insertion of the muscle into that 
of the flexor perforans digitorum, the slip to the great toe being but 
small compared with it. In the Dorking Fowl the flexor longus hal- 
lucis tendon splits into two (after it has given off the vinculum to the 
flexor perforans), one resulting portion going to the normal hallux 
and the other to the supplementary toe, which is therefore a hallux 
also, as is generally supposed. 
This manner of distribution of the deep plantar tendons, which 
is that found in a great number of birds, may be summarized as 
follows :—The flexor perforans digitorum splits opposite the meta- 
