I903 J Snodgrass, Gcospiza^ Cocoruis, and Certhidta. AOl 



Geospiza fortis and G. propinqua possess similar ridges. In G, 

 fuligiyiosa and G. scaiidcns there are only traces of them. They 

 are present in some form, either as plates or ridges, in most Passer- 

 ine skulls, varying greatly in size, but in G. streniia they are far 

 larger than in any other skull examined by the writer. 



The most striking feature about the skull of the thick-billed 

 Geospizce is the abrupt angle that the tomium of the upper mandi- 

 ble forms with the zygomatic bar. In G. strenua this angle is 

 1 1 8°. The same angle in Cardinalis is 140°. That is, the 

 detiexure of the upper mandible from the horizontal is 62° in G. 

 strenua and only 40° in Cardinalis. In G. strenua the distal 

 half of the bony culmen forms an angle of 90° with the basal part 

 of the culmen back of the nostril. This angulation is conspicuous 

 in all the species of Geospiza, although not so great in the smaller- 

 billed forms, and is characteristic of the genus. In Cardinalis 

 and Zamelodia there is no such angulation of the culmen in these 

 genera, as well as in smaller-billed Fringillidee, the culmen forms 

 an even curve from base to tip. 



Nasal bones large, the inferior or descending arm of each thick, 

 and forming nearly a right angle with zygomatic bar. Nostril 

 triangular, of almost an isosceles shape, lower rim horizontal and 

 on a level with upper edge of zygoma. Width of base of upper 

 mandible contained 2^ times in greatest posterior width of 

 cranium; depth i^ times in greatest posterior depth. Internasal 

 septum complete. 



Longitudinal bars of palatines thick, diverging slightly posteri- 

 orly, outward and downward, so that posterior ends lie below 

 level of zygomatic bar. Posterior ends blunt. Superior internal 

 laminae large, widened at dorsal edges and solidly fused with 

 rostrum of sphenoid, not projecting back of anterior ends of 

 pterygoids. Inferior internal laminae well developed. Lower 

 mandible extremely large, being specially deep just back of mid- 

 dle through coronoid process. Depth here more than a third of 

 the length. 



Geospiza fortis fortis Ridgway (Plate XVII, Figs. 4 and 5). — 

 This is one of the species with but a moderately large bill. The 

 interorbital area of the top of the skull is much narrower than 

 in G. strenua, being contained 2\ times in the distance betwaan 



