BIRDS. 343 



mechanism is, at the same time, the most simple and the 

 most effectual. Every one has prohably seen the lower part 

 of the leg of a Turkey when cut off,* preparatory to the fowl 

 being cooked; and, if so, may have, when a hoy, amused 

 himself hy pulling the tendons, which, acting upon the claws, 

 enahled him to make them contract or open at pleasure. 

 What he has done hy pulling the tendons is done in the 

 perching birds hy the tending of the leg, and, hy this simple 

 act, the bird, without effort, retains its hold, and does so 

 securely, even on one leg. The placing of the head under 

 the wing brings the centre of gravity more nearly over the 

 feet, and thus gives additional stability. 



From the number of species comprised in the Insessores, it 

 is convenient to divide the order into four groups, which are 

 again subdivided into families, genera, and species. The four 

 groups are established on very obvious characters, connected 

 principally with the form of the beak or of the foot. Some, 

 as for example the Thrush and the Robin, have, on the upper 

 mandible of the bill, a notch or tooth, 

 somewhat similar to that of the Falcons 

 (Fig. 263). These constitute the group 

 of tooth-billed birds; but the man of 

 science, instead of the English term, 

 which would only be understood here, 

 employs a compound Latin term (Denti- * lgl 263< 



sfrest), which means the same thing, and is understood by 

 men of science in every part of the world. The Sparrow has 

 a bill of a different shape (Fig. 264) ; it 

 is conical. Hence the Sparrow belongs 

 to another group, those with cone-shaped 

 bills (Conirostres). The third consists of 

 those birds which are remarkable for their 

 powers of climbing. In them the toes are 

 most usually arranged in pairs, two turned 

 forwards and two backwards, as may be Fig - 264< 



seen in the foot of the Cuckoo or the Woodpecker (Fig. 272). 



* It may here be remarked, that the true leg of a bird is the part to 

 which that name is given when a fowl is brought to table. The part called 

 the leg in the living bird lies between the leg, properly so called, and the 

 foot, and is analogous to that part of our foot which lies between the ankle 

 and the toes. 



f Latin Dens, a tooth 5 rostrum, a beak. 



