Strigidjl] 0STE0L0G1A AVIUM. [Strigin,e. 



Fam. 3. STBIGID-ZE. 



Subfam. 1. Striginje. 



Nyctea, Steph. 



Nivea, Thunb. type of Strigidse and Striginse. 



Cranium very broad in proportion to its length. Lacrymals wanting ; upper surface 

 much flattened, with a central depression extending from the nasal bones to the occiput. 

 Occipital protuberance very slight ; muscular impressions also slight. Orbits very large, 

 septa without perforations ; the process of the frontal bones bounding the orbits poste- 

 riorly much prolonged, and curved inwards at its extremity. Frontal bone at its 

 junction with the nasal gibbous, and with a deep transverse impression at the junction. 

 Upper maxillaries hooked, with the edges slightly waved ; foramen magnum horizontal, 

 rounded. Atlar tubercle rounded, broad. Palatine bones for their anterior third con- 

 sisting merely of a narrow strip of bone, then expanded and bent outwards, and again 

 gradually contracted and bending inwards to their posterior extremities. Interarticulars 

 with a strong central process extending backwards, and meeting a similar process extend- 

 ing forwards from the posterior or basal portion of the sphenoid. Nasal orifices oval, 

 wider anteriorly than posteriorly. Condyloid portions of the occipital bone strongly 

 developed. Vertebrae well developed and moderately strong. 



Sternum not convex longitudinally; edge of the keel slightly rounded, the point 

 slightly receding, from which to the manubrial process the anterior edge is very slightly 

 curved; manubrial process very small, consisting merely of a slight projecting edge; 

 posterior edge of the sternum indented on each side of the keel with two fissures, the 

 external one the largest. 



Pelvinal bones very strong, but with a few small foramina, showing the position of 

 the sacral vertebra?. Ilium projecting very much over the ischium, the latter placed 

 perpendicularly to the upper plane of the former ; ischiadic and obturator foramina very 

 similar to those of Sarcoramphus ; anterior part of the ilium very wide, nearly as broad 

 as the hinder portion ; the points of the os pubis curved much inwards. 



Bibs narrow, very little broader at their junction with the vertebrae than for their 

 whole length ; styliform process very long. 



Furculum weak in proportion to the size of the bird ; the rami flattened and becoming 

 much thinner and narrower as they approach the sternum, and without any process at 

 their junction. 



Coracoids strong, central portion somewhat triangular; axillary foramen large, the 

 channel well marked. 



Scapula long, of moderate strength, with a central depression for one-third of its 

 posterior length, expanded slightly near its extremity, and sloped off diagonally down- 

 wards. 



Humerus long, not very powerful, the superior ridge projecting much outwards. 

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