82 ANATOMY OF VERTEBRATES. 



{iv) in the Woodcock (Scolopax). In the Spoonbill (Platalcea) 

 and Flamingo {Plioenicopterus) the mid-trochlea is but little pro- 

 duced beyond the others. The surface for the attachment of the 

 innermost metatarsal (z) is raised well above the trochlear end of 

 the next {ii) in most of those Waders that have the back-toe. 

 Amono'st Natatores the Albatross has the three trochlea3 nearlv 

 on the same level : in others the mid one is usually most pro- 

 duced : in the Gannet and Pelican the outer trochlea is the 

 shortest and furthest from the middle one. In the Guillemot 

 ( Uriel) the inner trochlea {ii) ends at the base of the mid one, 

 whilst the outer trochlea is of nearly equal length with the mid 

 one : in the Grebe (Podiceps) the inner trochlea is the longest of 

 the three : in the Loon ( Columbus) it is the shortest : the meta- 

 tarsal in this bird is much compressed, and the outer and inner 

 trochlea are bent backward. The Penguins show the most in- 

 structive modification of the metatarsal : it is very short and 

 broad ; but the primitive divisions are to a great degree retained, 

 especially on the fore part of the compound bone. The stunted 

 or abortive metatarsal supporting the backwardly directed toe 

 consists of a trochlear articulation supported on a compressed 

 stem, twisted, and obtusely pointed above, with one margin 

 thickened and rough for syndesmosis with the next anchylosed 

 metatarsal. This bone is best developed in the Raptorial birds 

 and the Dodo,^ in which its length may exceed a fourth part 

 of the leno;th of the metatarsal seo-ment : in Pigreons it is about 

 the fifth or sixth part that length : by the twist the bone forms a 

 pulley upon which the flexor tendon of the back toe plays. In 

 the Dodo the distal expansion is increased by an obtuse process 

 from the outer side of the trochlea ; and this character is repeated 

 in the Cohimhidce.^ In GallincE the trochlea is less expanded 

 and the twist is feebly shown : it disappears in the still smaller 

 loose metatarsal of Apteryx, Palapteryx^ and in many Natatores, 

 in some of which it is represented by the ligamentous matter 

 tying the short back toe to the metatarse. 



Both this {i) and its metatarsal are undeveloped in the larger 

 existing Cursores, the Bustards ( Otis), the Plovers ( Charadicus), 

 the Thick-knees (^(Edicnemus), the Oystercatchers {Hcematopus), 

 the Coursers ( Tacliydromus), and the Albatrosses {DiomedcBa and 

 Haladromci). 



The toes of birds never exceed four in number, and of these, 

 three are usually elongated and directed forward, diverging, Avhile 



' XXVI'. 2 XXV1I-, pi, 11. 3 XVI-. vol. iii. p. 307. 



