90 Recent Literature. 



Understanding then the conformation of the bill, both in the breeding 

 season and in the winter, it remains to show how the change is effected. 

 The bird acquires its full breeding array in three ways : (1) by hypertro- 

 phy, (2) by horny growths, (3) by coloration ; and, conversel}^ loses it in 

 three ways, (1) by atrophy, (2) by loss of the horny growths, (3) by de- 

 coloration. 



The transformations of the bill relate exclusively, as already said, to the 

 hinder part. A. Upper Mandible : 1. The horny boss is that forked 

 piece which surrounds the base of the upper mandible. It is perforated 

 with many little holes in regular oblique series, through which rudimen- 

 tary perforating feathers pass out. In May, at the height of the breeding 

 season, it is transUicent, of a sort of flesh-color difficult to describe, more 

 or less tinged with yellow or violet, rather variable in shade in different 

 specimens. In falling off it loses this coloration, and becomes horn-yel- 

 low, like any claw about to be shed. It generally comes off whole, but 

 miay break apart at the top, or towards the middle of either of its forks. 

 Its fall leaves exposed the viembranous boss, in which the perforating 

 feathers are implanted, and which, the following season, reproduces a new 

 horny boss. 2. The nasal buckler, situated in front of the horny boss, is 

 forked like the last, and saddled on the upper mandible, having two broad 

 triangular sides united. It falls off in three pieces, — one large and two 

 small. The two little pieces (one on each side) called the subnasal lamel- 

 Ice are always detached first ; the large saddle-shaped piece follows ; but it 

 is so fragile that it is generally broken near the top before it finally falls 

 off. The author, however, succeeded in securing one nasal buckler intact, 

 this " pre'cieuse piece corne'e" coming from a wounded Puffin held by the 

 wings, who clawed it off in trjdng to defend himself. The nasal buckler 

 has the effect of causing a hard horny protuberance of the nasal region, 

 and thus thickening the base of the bill. Its loss uncovers the nasal mem- 

 brane, which in winter shrinks away from the forehead, and the following 

 spring produces a new buckler. 3. The pre-nasal fissure establishes the 

 sejjaration between the nasal buckler and the first or great ridge ; in win- 

 ter it is wanting, being replaced by the corresponding temporary groove. 



4. The transparent lamella is a horny pellicle of a beautiful orange-color, 

 which covers the hinder part of the first or great ridge, and is so closely 

 blended therewith as to be only distinguished in spring by its coloration. 

 This lamella grows transparent when about to fall, and is detached by ex- 

 foliation, exposing the first or great ridge, which is entirely red in winter. 



5. Ridges and groor>es. These are subject to no other changes than those 

 resulting from simple destjuamation and partial decoloration. B. Lower 

 Mandible. Its transformations are still more curious and note- 

 worthy'. 1. The horny selvage is of the brightest orange in the breeding 

 season. Its fall exposes the memhranous selvage, which, yellow at first, 

 soon loses its coloration. 2. The mental biicJcler represents both the nasal 

 buckler and the transparent lamella. It comes ofi' whole, its two sides joined 



