L78 OSTEOLOGY OF THRUSHES, MIMIX.E, AND WRENS, 



The pelvis is subject to considerable specific variation, although. 

 offering some fairly good points for comparative purposes. In general 

 terms the pelvis in the Thrushes may be said to be short and wide, the 

 width especially noticeable when the pelvis is viewed from behind. 



The ilia are short, anteriorly wide, with their transverse axes but 

 little inclined from the horizontal. 



In the Wrens the pelvis has a slightly compressed appearance, this 

 being due t<> the tact that the ilia are rather elongate and narrow, with 

 their transverse axes inclined at a considerable angle from the horizontal. 

 To use a familar simile the ilia of the Thrushes form a rather flat roof, 

 the backbone representing the ridgepole, while the ilia of the Wrens 

 form a roof having a great deal of pitch to it. In the shape of the ilia and 

 general appearance of the pelvis the Miminw are thoroughly Wren like. 

 The posterior iliac border exhibits great variety of shape, and while 

 Merula migratoria, Harporhynchus curvirostris and Salpinctes obsoletus 

 have what may perhaps be called the typical patterns of their respect- 

 ive groups, yet no one pattern is quite constant. 



The posterior iliac border of Tardus musicus and T. mustelinus bears 

 more resemblance to that of Harporhynchus than to that of either Merula 

 migratoria or M. aurantia. Mimus tits in very nicely between Galeo- 

 scoptes and Turdus mustelinus. Thyromanes is not very dissimilar to 

 J . mustelinus, and Melanoptila is in this particular even more like T. 

 mustelinus. The ilioneural groove is open in all the birds under consid- 

 eration with the exception of Campylorhynchus in which the ilia touch 

 and become anchylosed with the spinous processes. This character, if 

 it can be called one, is greatly affected by age, and its taxouomic value 

 is even more than doubtful. 



The last two presacrals are shorter, and their transverse processes 

 consequently nearer together in the Thrushes than in the Mimince or 

 Wrens, this difference being very perceptible when the Mimince and 

 Thrushes are compared with one another. In the Thrushes there is a 

 very noticeable ridge or keel along the under side of those pre-sacrals 

 which are fused with the '-sacral mass," a feature that is either very 

 slightly marked or altogether wanting in the Mimince and Wrens. 



The distinctive characters of the groups thus briefly dwelt upon may 

 be summed up as follows: 



II rem. — Ante-orbital region narrow. Descending process of nasal 

 slender. Angle formed by this process and " pars plana" rather open. 

 Maxillo-palatines acuminate posteriorly. Costal process of sternum 

 small, acuminate. Coracoid with a short flange on the epicoracoidal 

 portion. Pelvis anteriorly narrow, with the ilia much inclined from the 

 horizontal. 



Mimince. — Ante orbital region narrow. Descending process of nasal 



narrow. Angle subtended by this process and "pars plana" rather 



acute. Maxillo-palatines claviform (except Galcoscoptes). Costal pro- 



- moderate in size, somewhat acuminate. Coracoid with a moderate 



