Chap. V. 



OSTEOLOGICAL DIFFERENCES. 



167 



tumblers it is straighter, with the apex less elongated, than in the rock- 

 pigeon : in the woodcut, fig. 28, the scapulas of the rock-pigeon (a), and 

 of a short-faced tumbler (b), are given. The pro- 

 cesses at the summit of the coracoid, which receive 

 the extremities of the furcula, form a more perfect 

 cavity in some tumblers 

 than in the rock-pigeon : in 

 pouters these processes are 

 larger and differently shaped, 

 and the exterior angle of the 

 extremity of the coracoid, 

 which is articulated to the 

 sternum, is squarer. 



The two arms of the fur- 

 cula in pouters diverge less, 

 proportionally to their 

 length, than in the rock- 

 Fig. 23.— Scapula, of natural pigeon ; and the symphysis 



size. A. Rock-pigeon. j s more so \{& an( J pointed. 

 B. Short-faced Tumbler. T „ . .. ., , „ ,. 



In fantails the degree ol di- 

 vergence of the two arms varies in a remarkable 

 manner. In fig. 29, b and c represent the fur- 

 culse of two fantails ; and it will be seen that the 

 divergence in b is rather less even than in the fur- 

 cula of the short-faced, small-sized tumbler (a); 

 whereas the divergence in c equals that in a rock- 

 pigeon, or in the pouter (d), though the latter is a 

 much larger bird. The extremities of the furcula, 

 where articulated to the coracoids, vary considerably 

 in outline. 



In the sternum the differences in form are slight, 

 except in the size and outline of the perforations, 

 which, both in the larger and lesser sized breeds, are 

 sometimes small. These perforations, also, are some- 

 times either nearly circular, or elongated, as is often 

 the case with carriers. The posterior perforations 

 occasionally are not complete, being left open poste- 

 riorly. The marginal apophyses forming the anterior 

 perforations vary greatly in development. The degree 

 of convexity of the posterior part of the sternum 

 differs much, being sometimes almost perfectly flat. 

 The manubrium is rather more prominent in some Fi s- 29 -— Furcula, of natural 



. ,. . -, n , , ,, -. ,, . ,. size. A. Short-faced Tum- 



mdividuals than m others, and the pore immediately bier, b and c. Fantaii- 

 under it varies greatly in size. d. Pouter. 



Correlation of Growth— By this term I mean that the whole 

 organisation is so connected, that when one part varies, other 



