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Show 1876.] OF PASSERINE BIRDS. 507 C. J. Sundevall, in 1831, discovered that in the birds which he had the opportunity of examining that belonged to the order Passeres of Nitzsch, and only elsewhere in Upupa, the tendon of the flexor longus hallucis is quite independent of the flexor perforans digitorum pedis, a bond of union of one kind or other * joining them in other birds. Keyserling and Blasiusf, in 1839, established the law that (with the exception of the Alaudidae) those Passerine birds in which the form of the lower larynx (named " syrinx " by Professor Huxley) is what is known as "oscine," possess a pair of long scutes as a covering to the back of the tarso-metatarse. They may therefore be called bilaminate, to facilitate description, the term referring to the tarsal scutellation only. Johannes MullerJ, from his elaborate investigations on the structure of the syrinx in the South-American Passeres, was led to divide the group into two major sections-those in which the intrinsic muscles of the voice-organ are inserted into the ends of the bronchial semi-rings, and those in which they are inserted into their middle parts. I would suggest the name Acromyodi for the former of these divisions, and Mesomyodi for the latter-an acromyodian bird being one in which the muscles of the syrinx are attached to the extremities of the bronchial semi-rings, a mesomyodian bird being one iu which the muscles of the syrinx join the semi-rings in their middles. It seems to me advisable to restrict these terms to Passerine birds. Miiller found that among the mesomyodian Passeres there is a large collection of genera in which an easily recognized special type of syrinx exists. This group he separated off as " Tracheophonae," so naming them on account of the large share taken by the peculiarly modified lower end of the trachea in the formation of the voice-organ. In one respect he made a retrograde step, because he did not lay sufficient stress upon the value of Nitzsch's work ; and this was that he united the mesomyodian Passerine birds which are not tracheophone with those families which constituted the more expanded "Passeres" of Cuvier and with the Scansores, wavering between the two classifications, which may be expressed, with the employment of the term introduced above, as follows :- 1. PASSERES ACROMYODI (Oscines). 1. PASSERES ACROMYODI (Oscines). 2. PASSERES MESOMYODI TRACHEOPHONI. 2. PICARIJ**. 3. PICARI.E. a. Passeres mesomyodi a. Passeres Mesomyodi non- tracbeophoni. tracheophoni. b. Passeres mesomyodi non- Ac. tracheophoni. &c. From the above remarks it is evident that Miiller was led to lay too great stress upon the nature of the syrinx as a distinctive feature of the Passeres; and although Nitzsch was unacquainted with the * Vide Methodi naturalis Avium disponendarum Tentamen, 1872, p. xl. t Wiegmann's ' Archiv,' 1839. i. p. 332. 1 Abhand. d. Berl. Akad. 1846, p. 367. |
