1°73.] ANATOMY OF STKATORNIS. 529 



the acetabula, there is a weak feathering which blends with the 

 lumbar tracts. These last are consequently not very distinctly 

 denned and consist mainly of weakly feathered tracts, running 

 from the knee obliquely downwards and backwards, leaving the 

 tibiae almost bear, with the exception of a few semiplumes which are 

 scattered below the front of the knee. 



Between the rami of the jaws the large triangular surface is naked 

 at the sides and weakly feathered along the middle line up to the 

 symphysis (as in the Owls), where there are a few vibrissa:, directed 

 forwards. From this submaxillary feathered portion the inferior 

 neck-tract springs ; and behind the angle of the jaw a weak branch 

 is sent up, on each side, to join the dorsal tract and head-coverino- 

 behind the ears. A little lower down the inferior tract becomes 

 more defined, though not strong ; it continues simple as it descends 

 being of the same breadth as the lateral neck-spaces. Just above 

 the upper or scapular extremities of the furcula it ceases in the 

 middle line, leaving a bare interclavicular space ; but it develops a 

 branch on either side, which expands over the chest to form the nee 

 toral tracts. The pectoral tract of each side is double, the inner of 

 its divisions being the continuation of the main tract, which descends 

 narrow and strong, close to the carina sterni in its upper part but 

 further separated below, leaving over the epigastric region of the abdo 

 men a considerable median space, which lower down is again reduced 

 by their convergence to the anus, just in front of which they terminate 

 ±,ach outer pectoral branch of the inferior tract is weak and very" 

 diffused, covering the sides of the body, leaving a narrow space 

 between it and the mam stem, except at the points just in front of 

 the scapular ends of the furcula, from which they spring, and below 

 the inferior margin of the sternum, where they again blend, and con- 

 tinue down side by side, after their contact, nearly to the anus the 

 outer branch being the weaker and less defined. 



There is a weak hypopteral tract continued from the outer mar- 

 gin of the external pectoral branch. The under wing-surface is 

 leathered along the forearm in several rows. The margin of the 

 patagium is thickly set with short strong plumes. The humeral 

 tract is strong and separated by a narrow space from the well-covered 

 upper wing-surface. 



There is no aftershaft to the feathers. 



There are ten primary remiges, and twelve secondary, of which 

 the ten distal resemble each other, and the two at the elbow are 

 reduced in size. The upper wing-coverts do not extend more than 

 or quite so much as halfway down the secondary remiges There 

 are ten rectrices. 



The above described pterylosis clearly indicates that in the 

 arrangement of its feathers Steatornis more closely resembles the 

 Stngidse than the Caprimulgidaa, though it differs considerably 

 from both. It resembles the Stngidse and differs from the Capri- 

 mulgidae in having no aftershaft to the contour feathers, in not 

 haying the occipital tract divided up into narrow longitudinal rows 

 in having spaces on each side of the submaxillary tract, in having 

 Proc. Zool. Soc— 1873, No. XXXIV. 34 



