16 THE ORIGIN OF SPECIES 



companied by greatly elongated eyelids, very large external orifices 

 to the nostrils, and a wide gape of mouth. The short-faced tumbler 

 has a beak in outline almost like that of a finch ; and the common 

 tumbler has the singular inherited habit of flying at a great height 

 in a compact flock and tumbling in the air head over heels. The 

 runt is a bird of great size, with long massive beak and large feet; 

 some of the sub-breeds of runts have very long necks, others very 

 long wings and tails, others singularly short tails. The barb is 

 allied to the carrier, but, instead of a long beak, has a very short 

 and broad one. The pouter has a much elongated body, wings and 

 legs; and its enormously developed crop, which it glories in in- 

 flating, may well excite astonishment and even laughter. The 

 turbit has a short and conical beak with a line of reversed feathers 

 down the breast; and it has the habit of continually expanding, 

 slightly, the upper part of the oesophagus. The Jacobin has the 

 feathers so much reversed along the back of the neck that they 

 form a hood ; and it has, proportionally to its size, elongated wing 

 and tail feathers. The trumpeter and laughter, as their names ex- 

 press, utter a very different coo from the other breeds. The fan- 

 tail has thirty or even forty tail-feathers, instead of twelve or 

 fourteen — the normal number in all the members of the great 

 pigeon family; these feathers are kept expanded and are carried 

 so erect that in good birds the head and tail touch; the oil-gland 

 is quite aborted. Several other less distinct breeds might be speci- 

 fied. 



In the skeletons of the several breeds, the development of the 

 bones of the face, in length and breadth and curvature, differs 

 enormously. The shape, as well as the breadth and length of the 

 ramus of the lower jaw, varies in a highly remarkable manner. 

 The caudal and sacral vertebrae vary in number ; as does the num- 

 ber of the ribs, together with their relative breadth and the pres- 

 ence of processes. The size and shape of the apertures in the ster- 

 num are highly variable; so is the degree of divergence and rela- 

 tive size of the two arms of the furcula. The proportional width of 

 the gape of mouth, the proportional length of the eyelids, of the 

 orifice of the nostrils, of the tongue (not always in strict correla- 

 tion with the length of beak), the size of the crop and of the upper 

 part of the oesophagus; the development and abortion of the oil- 

 gland; the number of the primary wing and caudal feathers; the 

 relative length of the wing and tail to each other and to the body; 

 the relative length of the leg and foot; the number of scutellae on 

 the toes, the development of skin between the toes, are all points 

 of structure which are variable. The period at which the perfect 



