TIN AMI 



487 



The ccBca, it will be observed (fig. 231, p. 488), are well 

 developed, particularly in Bhynchotus rufescens ; they are 

 also large and very peculiar in form in Calodromas} The caeca 

 of this bird are not merely much wider than is customary, 

 but they are beset with numerous small diverticula, which 

 diminish in size towards the apex of the caecum. These 

 peculiar caeca are absolutely unique among birds, and nothing 

 at all like them has been described in any other tinamou. 



A curious feature of at any rate some tinamous (shared, 

 however, by the Anseres, Palamedeidae, some gallinaceous 

 birds, and perhaps Toccus) is the existence of two pairs of 

 extrinsic muscles upon the trachea. In Crypturus tataupa 

 one of these pairs is stouter than the other, and they are both 

 lost on the fascia covering lungs. This genus has no intrinsic 

 muscles. 



In other tinamous intrinsic muscles are present. 



In Calodromas elegans the anterior face of the lower part 

 of the trachea (about an inch in length) is covered with a 

 sheet of muscle, which is the extrinsic muscle, and probably 

 (judging from the conditions which obtain in the female) is 

 attached to the long fascia. The very broad intrinsic mus- 

 cles underlie this, and are inserted a long way down the 

 bronchus to the four or five rings following the third. When 

 viewed laterally the curvature of the last four tracheal rings 

 is seen to gradually increase ; there is thus a considerable 

 membranous interval left between the last tracheal and the 

 first bronchial, which is straight., The membrana, tympani- 

 formis is narrow. In the hen bird th^ extrinsic muscles are 



' Bbddabd, ' On the Caeca of Calodromas,' Ibis, 1890, p. 61. 



