[Auk 



462 Clark, Notes on Trochalopteron and Sicalis. [o^t 



the corresponding measurements are 5 mm., 25 mm., 12 mm. and 

 11 mm. So far as the shape and position of the tracts is concerned 

 there is no noteworthy difference, except perhaps the posterior 

 dorsal tract, which contrasts with the dorsal "diamond" much less 

 in the Robin than in the Chinese bird. The differences in the wings 

 of the two birds are so well known, they need not be dwelt on here 

 but it is at least interesting to note that in Planesticus the relative 

 lengths of the primaries run thus: 786954321 10. In Trochalop- 

 teron the arrangement is 54632178910 or the seventh primary 

 may slightly exceed the second and first. The important point is 

 that in the robin the wing is pointed by the outer primaries (6-9) 

 while in Trochalopteron it is the inner primaries (3-6) which give 

 the point. This is certainly a striking and perhaps an important 

 phylogenetic difference. In both genera there are 9 secondaries 

 and 12 rectrices as usual in passerine birds. 



In their internal anatomy I failed to find any point of difference, 

 between the two genera, which could be considered significant. 

 In both, the manubrium of the sternum is notably long and large 

 with a deep fork. In Trochalopteron, it is 6 mm. long, the arms of 

 the fork are 5 mm. apart at the tip and the fork is 2.5 mm. deep. 

 These measurements are in the fresh specimen. Of course, on a 

 dried skeleton they would be much less. 



The nostrils of Trochalopteron are very different from those of 

 the robin but unfortunately this difference is not nearly so well 

 shown in skins. In the Robin the nostril is a nearly horizontal slit, 

 largely concealed by a bare membrane, when looked down on from 

 above; the slit is widest posteriorly where its height is about one 

 fourth of its length. In Trochalopteron, the nostril is somewhat 

 kidney-shaped, oblique and quite unprotected by any membrane; 

 its length is somewhat more than twice the width. Judging from a 

 hasty examination of a number of skins, I think the character of 

 the nasal openings is more or less altered in drying. In no other 

 way can I account for the statement in the British Museum 

 'Catalogue' (Vol. VII, p. 326) that they are "longitudinal, with a 

 large operculum." Certainly that description does not apply at all 

 to the nasal openings in an alcoholic or freshly-killed Trochaloptero i. 

 canorum. 



