PBOCEEDINGS OF THE NATIONAL MUSEUM. 



567 



Comparison of Hie {/encra. 



Oeinis 



Ptcrylosis of tlio orown. 



Rictal liristlo: 



Pliiil.viioptilus I Loiiiiitudiiinl rows ! Present. 



Aiitidstoiiiiis 1 do do . . . 



iS'yctidronii s ' do do .. . 



Chordeiles do I Wniitiiii! 



Micropidlas | Uniform ' do ... 



Si eotyto do \ do 



Glaiicidiiim do | do . . . 



Aiaio I Longitudinal rows I do .. . 



Syrninni do I do . . . 



Aieaascops do ' do 



Gymuoglatix do : do . . . 



Strix Uniform do . . . 



Priniari.' formula. 



8=9,7:^10,6,5,4,3.2,1. 

 a 9, 7, 10, 6, 5, 4, ;i, 2, 1. 

 10, 9, 8, 7, 6,5,4, :i, 2,1. 



9=8,7,6=10.5.4.3,2,1.11. 

 7, 6,8, 5,4, 9,;!, 2, 1.10, 11. 

 9,8,7,10=6,5,4,3,2. 1, 11. 



7,6,8,5,9,4,3,2,10,1,11. 



9. 8, 10, 7,6,,-), 4,:',, 2, 1,11. 



Genus. 



Plia!aMioptilu.s . 

 Antro.'itonuis . . 

 Kyctidroiiiu.s .. 



Chordeilf s 



Micropallas 



Speotyto 



(ilaucidium. .. 



A.sio 



Syruium 



Megascops 



Gymnoglaux... 

 Strix 



Number 



of .second 



aries. 



12 

 12 

 12 

 13 

 13 

 15 

 14 or 15 

 15 

 16 

 14 

 13 

 15 



Ptervlosis of the feet. 



Xumber 

 of rec- 

 trices. 



Formula for 

 rectrice.s. 



Bare 



Tarsus feathered halfway down in front. 



Bare 



Tarsus feathered lialfway down in front. 



Fully feathered 



Feathered 1o hase of toeb 



do 



Fully feathered 



Almost fully feathered 



Fully featliered 



Tarsus feathered halfway down in front. 

 Feat licred to toes 



1.2. 3, 4. ,5. 



1,2,3,4,5. 



1,2,3,4,5. 



5,4,3,2,1. 

 , 1,2,3,4,5. 

 ! 1.2,3,4,5,6. 

 I 1,2,3,4,5,6. 

 I 1, 2, 3, 4, 5-, 6. 



1,2,3,4,5,6. 

 I 1,2,3,4.5,6. 



1,2,3,4,5,6. 



6,5,4,3,2,1. 



Having- thus set the more important facts before us in a condensed 

 and therefore convenient form, let us see what inferences, if any, can 

 be drawn from them. In order to estimate correctly the value of like- 

 nesses and the weight of differences, one must first consider the rela- 

 tive importance of the different pterylographical characters in auy 

 two groups. We may safely assert that the most importance attaches 

 to the fundamental ])lan of the pterylosis, while slight variations carry 

 little weight. This is to be inferred from the uniform pterylosis of 

 clearly defined groups such as the Grouse or even the Passeres. Next 

 to this I should rank the condition of the wing, whether acpiiucubital 

 or not, and the number of rows of coverts and then the condition of 

 tlie oil-gland tuft, aftershaft, and down. The number of rectrices, 

 lemiges, and feathers in the alula arc much more variable and depend 

 to some extent jjerhaps on the size of the bird, but of course agreement 

 in these details would carry more weight than differences. Less valu- 

 able would be the denudation of the tarsus and tibia, which is more or 

 less dependent on the habits of each species, while the least impor- 

 tant of all characters is tiie presence or absence of peculiar feathers 

 or crests, because these often differ even in the two sexes of the same 

 species. Estimating* tlie value of the characters in this way, let us 

 now examine, under the following four heads, the comparative ptery- 

 lography of the two groups before us: (1) fundamental plan of ptery- 

 losis, together with its variation in detail; (2) arrangement of the 

 feathers of the wing; (3) aftershafts, oil gland, and down; (4) tail. 



