6 Osteology of Circus hudsontus. 
be observed also that the sutural traces of the nasal processes of 
the pre-maxillary are quite distinct in adult skulls, while in some 
Falcons they are entirely obliterated. The distance between the 
1. Left lateral view of the skull and nuandible of Circus hudsontus. 
Fig. 2. The same specimen from above; mandible removed. 
Fig. 3. The same seen from below ; mandible removed. 
Fig’ 4. The hyoid arches from below, All these figures are life size from nature, from air 
adult female subject collected by the author in Wyoming (1878), 
Fig. 
superorbital margins is very narrow, and a shallow, longitudinal, 
median groove courses between them, nearly as far in a backward 
direction as the supra-occipital prominence. The parietal emin- 
