46 DESCRIPTIONS OF PREPARATIONS. 



10. COMMON PIGEON (Cohimba livia), 



Showing nervous, digestive, circulatory, and parts of respiratory and renal systems. 



THE brain has been exposed in situ by the removal of the roof of the 

 cranium ; the integument has been removed from the right side of the 

 front of the cervical region, as have also most of the feathers from the entire 

 body ; an opening has been made into the right side of the crop, which has 

 been distended ; the larger part of the right half of the body walls has been 

 removed, together with the muscles and the limbs which it supported, and 

 a red injection has been thrown into and filled the venous system. 



The surface of the cerebral hemispheres is smooth ; the proportion of 

 the encephalic nervous mass to the intraspinal is much greater than in the 

 cold-blooded Vertebrata. The backward projection of the cerebellum is 

 very considerable. The eyes are large. The vertical third eyelid is drawn 

 forward. The nostrils open externally as long slits overhung by a soft, 

 bare, tumid membrane 1 ; the external auditory meatus, which has no concha, 

 has the feathers arranged round it like a circlet of tentacles. The great 

 pectoral muscle, the main depressor of the humerus and the wing, is seen 

 in section along its origin from the lower portion of the keel of the 

 sternum, and from the furculum, the outer and lateral portions of the 

 sternum, from which it also took origin, having been removed. Placed 

 dorsally with reference to this muscle we see the second pectoral, the main 

 elevator of the humerus and the wing, arising from a larger portion both 

 of the keel and of the lateral parts of the sternum than the pectoralis 

 major, and passing internally to the coracoid to enter the pulley-like canal, 

 the foramen triosseum, formed by the clavicle or furcula, the coracoid, and 

 the scapula. This muscle is supplied by nerves which pass in front of, 

 whilst the great pectoral is supplied by nerves which pass below the 

 coracoid, the first being homologous with the subclavian, the second with 

 the anterior thoracic nerves of anthropotomy. 



Whilst the tendon of the second pectoral or great levator humeri muscle, which 

 is cut short, is seen issuing from its canal on the further side of the glenoid articular 

 surface; on the proximal side, the humerus having been removed, we see the 

 tendon of the biceps, homologous with the ' short head ' of anthropotomy. The 

 cut-short triangular end of the pectoralis major is seen to become partially bifid 



1 This membrane is sometimes called a ' cere,' but it is better to restrict the term to the denser 

 structure similarly placed in and similarly distinctive of the Aetomorphae and Psittacomorphae. 

 Some of the Charadrii-morphae (Plovers), which on account of a peculiarity in the nasal bones (in 

 which they resemble the Pigeons) were placed with them in a separate order, the Charadriifonnes, s. 

 Schizorhinae, resemble them also in the conformation of this membrane. See Coues, Key to 

 American Birds, 1872, p. 26; Strickland and Melville, The Dodo and its Kindred, p. 46 ; Garrod, 

 P. Z. S. 1873, p. 33, 1874, p. ioo. 



