THE TETRAONID.E. 113 



With regard to the oil-gland, I have still to state that it has usually a flat, cordate form, but 

 is perfectly elliptical in Crypturus and entirely wanting in Argus. In the first case it possesses 

 a very distinct mamilla, the extremity of which is surrounded by a circlet of six or seven large 

 umbellate plumes ; in the second case the mamilla is wanting, and the scarcely perceptible orifices 

 are situated on the upper surface of the gland, surrounded by four umbellate plumes. The two 

 halves are always distinctly separated, although placed close together, and each of them contains 

 a very wide cavity, extending deeply into the interior. 



This great and almost complete agreement renders it impossible to group the genera of 

 Gallinaceas pterylographically. I prefer, therefore, employing the groups that I have established 

 upon other generally anatomical characters, describing the species observed in each group, and in- 

 dicating such deviations as I have been able to detect. In the first place, as has already been 

 remarked under the Pigeons, I separate the SAND-GROTJSE (Syrrhaplidce) from the Gallinacese. 

 I then divide the latter into two main groups, one of which includes only the genera Hemipodius, 

 Crypturus, and Megapodius ; the other all the rest of the Gallinaceae. The latter, again, may be 

 divided into Tetraonida, Phasianida, and Penelopidce} 



1. TETRAONID/E. 



1. Tetrao. Judging from the examination of T. layopus, cupido, umbellus, hybridus, tetrix and 

 uroffallm, the characters of the pterylosis are nearly as in Meleayris (Plate VII, figs. 9 and 10), 

 but it appears to me that a rather strong formation of the fork of the scapular portion of the 

 dorsal tract is characteristic of the Tetraones ; the lanceolate spinal space also may be a little 

 longer. The main stems of the inferior tract are united from the extremity of the sternum 

 onwards, and this common part is here rather long. In the wings of T. umbellus I counted twenty- 

 five, in T. cupido twenty-eight, in T. hybridus twenty-six, in T. tetrix twenty-five, and in T. urogallus 

 twenty-nine remiges, of which the third or fourth is the longest, and the eleventh strikingly 

 abbreviated. The tail in all these species contains eighteen feathers. 



2. Perdix. Of this genus I have examined P. cinerea, petrosa, saxatilis, javanica, dentata, 

 TEMM. (ffuianensis LATH., LICHT.), marylandica, and coturnix. In two, namely P. petrosa 

 and javanica, I found a narrow spinal space in the same position as in Tetrao and Meleagris, and 

 also exactly the same form of dorsal tract ; in the others I did not observe this space, although 

 the dorsal tract has precisely the same form. In all of them, the pectoral band is remarkably weak 

 and almost gap-like anteriorly close to the outer branch, and the ventral portion of the two 

 bands is united into one. The lumbar tracts are free. P. coturnix, dentata, marylandica 

 and javanica have twelve tail-feathers and from twenty-two to twenty-three remiges ; in P. petrosa 

 and saxatilis I found fourteen rectrices and twenty -four remiges ; P. cinerea has eighteen feathers 

 in the tail and twenty-three in the wing. In the Quails, as is well known, the first primary is 

 the longest; in the true Partridges, on the contrary, the third, fourth, or fifth; the first three 



1 On the anatomical peculiarities of these groups consult my observations in Naumann's 

 ' Naturgeschichte der Vogel Deutschlands,' vol. vi, pp. 270 and 429. 



15 



