88 E VOL UTION AND DISEASE. 



may have a persistent branchial cleft, another have 

 a cervical auricle only, and a third a persistent cleft 

 and auricle. It is also a point of some interest to re- 

 member that in the human subject the operculum of 

 the third cleft is that most commonly seen in the adult. 



The pendulous bodies in the goat harmonize admir- 

 ably with these conditions. Professor Charles Stewart 

 detected in the auricle of the goat figured on page 84, 

 an axial rod of coarse, yellow elastic cartilage, and 

 Franck, in his work on the "Anatomic der Hausthiere," 

 1883, states that in goats and pigs* this rod of cartilage 

 exists in these so-called bells (Glockchen oder Ber- 

 locken), and draws attention to the existence also of 

 striped muscle-fibre in them. The anatomy of a 

 goat's cervical auricle is shown in fig. 45. As these 

 bodies occur in goats at the situation of the external 

 orifice of the third branchial cleft, most anatomists 

 are of opinion that they are homologous with the 

 cervical auricles of man. 



An impartial consideration of the evidence relative 

 to the development of the pinna in land mammals 

 shows, clearly enough, that it is to be- regarded as the 

 confluent opercula of the first and second arch, extra- 

 ordinarily developed from increased use in connection 

 with the acoustic functions, which have gradually 

 arisen in connection with the first branchial cleft. 

 The remaining opercula have been suppressed partly 

 from loss of function and partly from the excessive 

 development of the first and second operculum. That 

 the gradual development and increased importance of 

 the external auditory apparatus is in a large measure, 



