344 STRUCTURE AND CLASSIFICATION OF BIRDS 



Comments upon the facts set forth in the arbove table must 

 obviously be discounted by the variations (quite considerable ' 

 in amount) which occur in one or two of the species. The 

 table given by Gadow ^ increases the number and extent of 

 the individual differences in intestinal length. 



In the liver the right lobe is, as a rule, larger than the 

 left. Sometimes it is only slightly so ; but in Charadrius 

 pluvialis the right lobe is twice as large. In Scolopax rusti- 

 cola and in CEdicnemus crepitans the lobes are equal. The 

 gall bladder is nearly always present. Gadow did not find it 

 in a specimen of Numenius arquatus and of Tringa arenaria 

 and T. alpina. This, however, appears to be individual. 



In all the Charadriidse the syrinx is of the tracheo-bron- 

 chial pattern. 



In Vanellus cayennensis ^ (fig. 46, p. 66) the last twenty- 

 five tracheal rings are narrower than those which precede them, 

 and of equal diameter throughout. The first two bronchial 

 semi-rings are like split tracheal rings ; the next two are very' 

 closely applied together ; the remainder are normal bronchial 

 semi-rings with no modification. The most remarkable fact 

 about the windpipe is the enormous size of the intrinsic 

 muscles, of which, however, there is only a single pair. The 

 muscles end in a tendon, which is inserted on to the second, 

 third, and fourth semi-rings. In Vanellus eristatus the intrin- 

 sic muscles are certainly large, but not so abnormal as in the 

 other species of the genus. Only the last four tracheal rings 

 are modified, and in front they are all fused in the middle 

 line to form a bony box ; behind the last three tracheal rings 

 are semi-rings, the pessulus being attached to the fourth. 

 The muscles are attached to the first bronchial semi-ring. 



In Himantopus nigricoUis there was no trace what- 

 ever, that I could detect, of these . muscles ; nor in H. 

 brasiliensis. Charadrius pluviaMs, Hcematopus ostra- 

 legus, and Squatarola helvetica are also without these 

 muscles. On the other hand they are present in Totanus 



' In Broun's Thierreich, ' Aves,' p. 624. 



'' Garhod, ' On the Trachea of Tantalus loculator and of Vanellus cayen- 

 nensis,' P. Z. 8. 1878, p. 625. 



