MOEPHOLOGY OF THE OWLS, 267 



Garrod (5) tackled this question after an examination of the pterylosis of Steatornis, 

 which he compares with the Owls on the one hand and the Caprimulgkl(B on the other. 

 Judging from internal evidence, I should say that it is prol)ahle that his information 

 concerning the two latter groups Avas gleaned from Nitzsch rather than at first hand. 

 This latter author, by the way, it will be remembered, noticed that in his Caprimulgi 

 " the forms of the tracts, singularly enough, have a remarkable resemblance to the type 

 of several Rapacious Birds, but differs in tlie various genera. Among these analogies I 

 reckon the forking and interruption of the spinal tract between the shoulder-blades in 

 Caprimiilgus, the emission of an interior branch from the end of the gular portion of 

 the inferior tract in Nyctornis, and the division of the dorsal and rump portions of the 

 spinal tract in the same genus." And in describing the pleryla ventraUs of Nyctornis 

 he writes : — " Inferior tract divided from the throat, emitting a narrow cu.rved inner 

 branch which extends ujion the breast at the lower extremity of the neck. Behind this 

 branch it is so diminished that it becomes nearly interrupted, as in Gypaetos, to the 



inferior tract of which it has a great resemblance In this bird also a hook 



originates from the end of the jjectoral band and runs to the hy^wpteron." 



Thus it is evident that Nitzsch regarded the similarity in the disposition of the tracts 

 in certain Cuprinmlgi and certain "Rapacious Birds" as an interesting coincidence 

 rather than proof of affinity. Moreover, he dwells rather upon the similarity between 

 this group and the Accipitres proper than between this group and the Owls. 



To resume : Garrod, after describing the pterylosis of Steatornis — which, except for 

 the spinal tract, agrees apparently pretty much with Caprlmulgus — concludes that " the 

 above-described pterylosis clearly indicates tliat in the arrangement of its feathers Steat- 

 ornis more closely resembles the Strigidcs than the Caprimidgidce, though it differs 

 considerably from both. It resembles the Strigidce and differs from the Caprimulgida 

 in having no aftershaft to the contour-feathers *, in not having the occipital tract divided 

 up into narrow longitudinal rows, in having spaces on eacli side of the submaxillary 

 tract, in having the pectoral portion of the inferior tract in two parts, of which the inner 

 approaches the carina sterni above and separates from it as it descends, in having the 

 upper wing-surface uniformly feathered, and in having a large infuudibuliform oil-gland. 

 In none of the Caprimulgidce does the inferior tract continue simple down the neck, 

 whilst in Strix jiammea, as in Steatornis, it does not bifurcate till in tlie region of the 

 furcula. But Steatornis resembles the Caprinmlgidcc and differs from the Strigidce in 

 having ten rectrices ; it differs from both, however, in that the inferior portion of the 

 dorsal tract does not unite at all with the scapular fork of the superior portion, in 

 having the outer Ijranch of the pectoral tract diffused and descending far over the 

 abdomen, and in the general tendency to the scattering of the feathers." 



Of the points in which Steatornis is supposed to resemble the Owls the most important 

 are the second and fourth, but in this last tlie resemblance is not very close. As 

 Garrod points out, Steatornis differs considerably from both Striges and Caprimulgi. 

 Further evidence on the question has yet to be tqiken, which is that of the microscopical 



* Dr. Gadow has poiutfd out (3) that in this Garrod was mistaken ; the aftershaft is of considerable size. 



