282 COLUMBA LIVIA. 



Length to end of tail 13 inches; extent of wings 26; w^ng 

 from flexure 8f ; tail 4i ; bill along the edge 104 twelfths; 

 tarsus 1/3 ; middle toe and claw 1 inch 7i tw^elfths. 



The Domestic Pigeon being undoubtedly the descendant of 

 the Rock Dove, I have thought it well to compare the diges- 

 tive organs of both. Figures 1, 2, 3, and 4, represent those of 

 the former ; Figs. 5, 6, and 7, those of the latter. The same 

 letters are used in both cases. 



In Fig. 1 . are seen, a, the bill ; a, ^, c^ the part of the oeso- 

 phagus anterior to the crop, and much dilated ; c, d, e, /, the 

 crop, transverse and a little contracted in the middle ; /, p, k, 

 the intrathoracic part of the oesophagus ; y, the proventriculus ; 

 h, the upper lobe of the stomach ; i, the right lateral muscle ; 

 j\ the left lateral muscle ; ^, the inferior muscle ; I, one of the 

 tendons ; m, n, 0, the duodenum ; p, q, r, 5, the rest of the in- 

 testine. 



Fig. 2. represents a section of the proventriculus, shewing 

 the very short broad glandules. 



Fig. 3. shews the upper or posterior face of the stomach ; 

 p, the proventriculus ; k, the cardiac lobe ; i, j\ the lateral 

 muscles ; ^, the inferior muscle ; /, the tendon ; w, the com- 

 mencement of the intestine. 



Fig. 4. the rectum, b, c ; and the coeca, d, e. 



In the Domestic Pigeon, the parts differ very little. The 

 crop is generally larger, and the coeca a little longer ; but 

 in other respects the parts are precisely similar. The oeso- 

 phagus, a, &, c^f, g^ w^hich is six and a half inches long, is im- 

 mediately dilated to the diameter of an inch and a quarter, and 

 gradually enlarges so as to form a sac or crop three inches long, 

 and about the same breadth. In general, the internal surface 

 of the crop is smooth ; but when the bird has young, or at 

 least under certain circumstances, it is rugous, being covered 

 with reticulated prominent ridges, highly vascular, and secret- 

 ing an abundant mucous or gelatinous fluid. This structure 

 is represented by Fig. 6. The lower orifice of the crop has 

 several very prominent longitudinal rugae, and is plentifully 



