INTRODUCTION 67 



asserted the truth, when he said that the general structure, but especially 

 the muscular appendages, of the lower larynx was " similarly formed in 

 all other birds of this family " described in Audubon's work. Mac- 

 gillivray did not, however, assign to this essential difference any systematic 

 value. Indeed he was so much prepossessed in favour of a classification 

 based on the structure of the digestive organs that he could not bring 

 himself to consider vocal muscles to be of much taxonomic use, and it 

 was reserved to Johannes Mitller to point out that the contrary was the 

 fact. This the great German comparative anatomist did in two com- 

 munications to the Academy of Sciences of Berlin, one on the 26th June 

 1845 and the other on the 14th May 1846, which, having been first 

 briefly published in the Academy's Monatsbericht, were afterwards printed 

 in full, and illustrated by numerous figures, in its Abhandlungen, though 

 in this latter and complete form they did not appear in public until 

 1847.^ This very remarkable treatise forms the groundwork of almost 

 all later or recent researches in the comparative anatomy and consequent 

 arrangement of the Passeres, and, though it is certainly not free from 

 imperfections, many of them, it must be said, arose from want of material, 

 notwithstanding that its author had command of a much more abundant 

 supply than was at the disposal of Nitzsch. Carrying on the work from 

 the anatomical point at which he had left it, correcting his errors, and 

 utilizing to the fullest extent the observations of Keyserling and Blasius, 

 to which reference has already been made, Miiller, though hampered by 

 mistaken notions of which he seems to have been unable to rid himself, 

 propounded a scheme for the classification of this group, the general truth 

 of which has been admitted by all his successors, based, as the title of his 

 treatise expressed, on the hitherto unknown different types of the vocal 

 organs in the Passerines. He freely recognized the prior discoveries of, 

 as he thought, Audubon, though really, as has since been ascertained, of 

 Macgillivray ; but Miiller was able to perceive their systematic value, 

 which Macgillivray did not, and taught others to know it. At the same 

 time Miiller shewed himself, his power of discrimination notwithstanding, 

 to fall behind Nitzsch in one very crucial point, for he refused to the 

 latter's Picari^ the rank that had been claimed for them, and imagined 

 that the groups associated under that name formed but a third " Tribe " 

 — PiCARii — of a great Order Insessores, the others being (1) the Oscines 

 or Polymyodi — the Singing Birds by emphasis, whose inferior larynx was 

 endowed with the full number of five pairs of song-muscles, and (2) the 

 Tracheophones, composed of some South-American Families. Looking on 

 Mtlller's labours as we now can, we see that such errors as he committed 

 are chiefly due to his want of special knowledge of Ornithology, com- 

 bined with the absence in several instances of sufficient materials for 

 investigation. Nothing whatever is to be said against the composition of 



Ptilogonys, now known to have no relation to the Tyrannidse, were included, though 

 these forms, it would seem, had never been dissected by him. On the other hand he 

 declared that the American Redstart, Muscicapa, or, as it now stands, Setopliaga 

 ruticilla, when young, has its vocal organs like the rest — a statement corrected by 

 Miiller in a Nachtrag (p. 405) to his paper next to be mentioned. 



1 Also printed separately as Ueber die Usher unbekannten typischen Verschieden- 

 heiten der Stimmorgane der Passerincn, 4to, Berlin : 1847. 



