bo Lucas oh the Os Proniitiois, 



olive-green on the upper parts, they tlillv equal any ot" the California fe- 

 males. The supposed difference in the tail markings of these races does 

 not hold in the series before me, for a male from Nicasio has the edging 

 on the inner webs of the rectrices quite as broad and pure as that of any of 

 the Florida ones. The loss of this character, however, would be of little 

 consequence, as the two forms could be readily separated by the wide dif- 

 ference in their general coloring. Mr. Henshaw considers his Arizona 

 specimens true cclata, and lutescei/s is now for the first time announced 

 from that Territory. 



290, 5 ad., Tucson, April 26. Length. 5; extent, 7.30: wing, 2.45; 

 tail, 2.10. "Iris dark brown; bill blacky, lighter at base below; legs dark 

 brown. Not common." 



291, $ ad., same locality and date. Length. 4.70; extent, 7.10: wing, 

 2.37: tail, 2.09. Same remarks. 



( To he co7if/>iHed.) 



NOTES ON THE OS PROAIINENS.* 



BY FREDERIC A, LUCAS. 



My attention was lirst directed to this bone by Dr. Shufeldt's 

 article in this Bulletin for October, 1S81, and subsequently b}- Mr. 

 Jeflries' paper in the number for January, 1SS3. With the view 

 of ascertaining in what birds the os prominens is present, and 

 what is its use, I have since examined quite an extensive series 

 of birds. Lack of time has prevented as extended an examina- 

 tion as could be wished for ; and as regards discovering any spec- 

 ial use for this sesamoid, it must be confessed that the results of 

 the investigation are not wholly satisfactory, being rather negative 

 than positive in their character. But such as they are, they are 

 submitted, in the hope that they may prove of service to some 

 better skilled physiologist. 



Through a lack of good material Dr. Shufeldt failed to dis- 

 cover the existence of the os prominens in any of the Owls, but 

 it would seem to be specially characteristic of the Bubo)iid(r, 

 since it is present in one particidar shape, and with a constant 

 mode of articulation, in the following species of that family: 

 Ketupa ccylonensis^ K. javanensis^ Btibo ignavus^ B. be7iga1- 



* The name "os prominens," proposed by Dr. Shufeldt, has been adopted by me 

 because it seems eminently proper that so large a sesamoid, frequently equalling the 

 patella in size, should receive a distinctive appellation. 



