416 Snodgrass, Geos/>/z<i, Cocorm's, and Certhidia. \^^^^ 



IV. The Alimentary Canal. 



No descriptions need be given of the alimentary canals. Fig- 

 ures 27 to 33 on Plate XIX sufificiently show the intestinal windings 

 in several species of Geospiza and also in Cocornis and Ccrthidia. 

 It will be seen that there is no essential difference here between 

 the three genera. 



V. PrERVLOSIS. 



The pterylosis is identical in the three genera. Figures 21 and 

 26 of Plate XVIII, representing the feathered areas of Cocornis 

 agassizi, could serve just as well for either Certhidia or Geospiza. 

 The dorsal tract extsnds down the back of the neck and between 

 the shoulders as a narrow, median band. On the middle of the 

 back it expands into a wide, fusiform area reaching to the 

 anteriorpart of the lumbosacral region. Here it again contracts 

 to a narrow band, narrowest between the acetabula, and goes 

 caudally to the oil-gland. The ventral tract begins as a median 

 band on the anterior half of the throat. Just below the middle it 

 divides into two bands that go outward and caudally as wide 

 tracts along the sides of the breast. Behind the sternum each 

 becomes again narrow, and goes caudally and inward along the 

 side of the abdomen, ending near the anus. At the shoulder each 

 lateral ventral tract gives off laterally the shoulder tract wliich 

 divides into the alar and humeral tracts. 



Explanation of the Plates. 



Plate XVII. Skulls. Figs, i and 2, Geospiza sireiiiia ; 3, Zamelodia 

 melanocephala ; 4 and 5, Geospiza fortis fortis ; 6 and 7, 

 G. fuliginosa parvula; 8 and 9, G. fuliginosa acutirostris ; 

 10 and II, Cocornis agassizi; 12 and 13, Certhidia olivacea 

 liiteola; 14 and 15, Geospiza crassirostris; 16, 17 and 18, 

 G. scaiidens fafigata. 



Plate XVIII. Fig. 19, Cocornis agassizi, inner view of bones at slioulder; 

 20, C. agassizi, side view of thoracic skeleton; 21, C. 

 agassizi, ventvaX pterylosis; 22, C. agassizi, ventral view 

 of sterninn ; 23, 24 and 25, Geospiza fuliginosa parvula. 



