26 Mr. W. A. Forbes o?^ the late Professor Garrod's 



generic groups in the immense mass of Passerine birds was 

 always a favourite object Avitli Prof. Garrod; and the four 

 papers quoted above '^ are the published results of his efforts 

 at a solution of the difficulties that have always attended the 

 classification of this group. It was whilst working at Pas- 

 serine birds that the classificatory value of the mode of termi- 

 nation of the tendon of the tensor patagii brevis muscle, 

 already alluded to {supra, p. 16), first attracted his attention. 

 The presence also in certain Passerine birds, the Cotingidse 

 and Pipridse, of a femoral instead of a sciatic artery has also 

 been mentioned. A slight exception, too, to SundevalFs 

 generalization about the independent muscular supply of the 

 hallux in Passerine birds {supra, p. 13) was found by him to 

 exist in the Eurylsemidse (P. Z. S. 1877, p. 447). But the most 

 novel fact pointed out by Prof. Garrod as regards these birds 

 is that they may be divided into two main groups, according 

 as to whether the intrinsic muscles of the syrinx are inserted 

 into the eiids or into the middle of the bronchial semirings. 

 The former group, called by him Acromyodi, includes all the 

 ordinary singing-birds with four or five pairs of muscles, the 

 Oscines, together with two aberrant Australian groups, formed 

 by the genera Menura and Atrichia. In these the number 

 of intrinsic muscles is reduced to three and two pairs respec- 

 tively ; but they are still inserted into the tips of the semi- 

 rings t- 



* Togetlier with liis appendix to the English edition of Johannes Miil* 

 ler's ' Stimmorgaue del' Pnsserinen.' 



t I may here remark that I cannot at all agree with Mr. Sclater's view 

 on the position of these two genera, which form his group " Pseu' 

 doscines " (Ibis, 1880, p. 345). By placing Atrichia and Menura away 

 fl'om the other Acromyodian Passeres, and interpolating the Mesomyodian 

 ones, the important fact is ignored that, in their possession of an " Acro' 

 myodian " syrinx, these birds depart essentially from the typical avian 

 " Mesomyodian " structure, the one which there cannot be the shghtest 

 doubt is the more primitive form. " The much more important osteo- 

 logical characters" in which these two forms are said to diverge from the 

 other Passeres are, as far as I am aware, two only ; and these, moreover, 

 are individual pecidiarities of each genus, and by no means common to 

 the two forms — in Menura the curved posterior margin of the sternum. 



