138 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Vol.Vl. 



There are seven coccygeal or caudal vertehrce, rarely only six, and the 

 pygostyle ; they are in the skeleton so arranged and articulated that 

 they have, as a whole, a gentle curve upwards, terminated by the quad- 

 rate " coccygeal vomer". 



These segments are all free, being easily individualized, even before 

 maceration, by simple section of the ligaments that bind them together. 



The subcircular neural canal, that passes through them, almost capil- 

 lary in its dimensions, terminates without passing into the pygostyle. 



There is no hsemal canal developed, and indeed hypapophyses are 

 found as stunted tubercles only on the last two or three vertebrsB. 



A neural spine is developed on each, as a prominent and curved "pro- 

 cess" pointing forwards; this spine is wanting, however, on the last 

 caudal. 



Of the lateral apophyses the transverse processes seem to be the only 

 ones entitled to any consideration ; these, as broad, flattened lamina, 

 extend from each vertebra, downwards and outwards, decreasing in 

 width from before backwards ; in fact, each vertebra in the coccygeal 

 series becomes more and more rudimentarj' as we proceed in that di- 

 rection. 



The articular facettes ujjon the centra start reniform, to terminate 

 almost circular in the last vertebra ; and the zygai3ophysial processes 

 are exceedingly elementary in character. 



The pygostyle is parallelogramic in outline, articulating with the ulti- 

 mate coccygeal vertebra by an unperforated cup-shaped depression, at 

 the middle of its long anterior side. The edge of the bone above this 

 point rests on the posterior border of the neural spine of the last caudal j 

 below it is free. 



The superior angle is more or less produced, and the posterior corner 

 of the i)arallelogram is expanded laterally ; this expansion is highly 

 developed in manj" birds, as in Colaptes mexicanus and other members of 

 the family Ficidcc. The caudal vertebrae are non-pneumatic in our pres- 

 ent subject, whereas in the pelvis we find these foramina in their usual 

 localities. 



The scapular arcJi— (PI. lY, Figs. 22, 30, 32, 33, and 34).— This arch 

 is very strong and perfect in this bird, as it is among the Oscines gen- 

 erally. 



The bones can be easily separated from each other by maceration^ 

 though during life they are remarkably well strapped together and to 

 the sternum by their numerous ligaments. 



The scapula lays along the dorsum in its usual position over the dorsal 

 pleurapophyses, parallel with the vertebrae, with its posterior point 

 touching the fifth one in the vast majority of the specimens. 



Certain bones in all skeletons force upon us their resemblance to fa- 

 miliar objects, and we know many of them have received their distinct- 

 ive appellations through such likenesses ; more particularly is this the 



