516 MR. A. H. GAKROD ON THE ANATOMY [June 6, 



Menura superba, from the above description, is therefore acroinyo- 

 dian, although not typically Oscine. 



Atrichia rufescens presents precisely the same arrangement as 

 Menura. There are three modified bronchial semirings, the third 

 descending posteriorly, and the second expanded a short distance 

 before it reaches its anterior termination, the anterior longitudinal 

 muscle being there inserted. The posterior muscle, however, does 

 not clearly separate into two before it reaches its points of insertion, 

 which are identical with those in Menura. The lower tracheal 

 rii>gs are different, in that they are not flattened from above down- 

 wards ; they retain the characters of those above them to a great 

 extent. The last forms the characteristic three-way piece. In Plate 

 LII. figs. 4, 5, & 6 these points are clearly seen. 



Atrichia is therefore also Acromyodian, although far from being 

 normally Oscine. It would require but little modification in either 

 it or Menvra to convert their syringeal muscular masses into more 

 numerous independent muscles. In the Crow, Starling, and most 

 of the other Oscines I have examined, the third semiring is the one 

 to which the long anterior muscle runs, the long posterior not going 

 beyond the second. This condition is just reversed in the two birds 

 under consideration. In the Finches the arrangement described by 

 Cuvier maintains, both anterior and posterior long muscles running 

 to the third bronchial semiring. 



In Plate LII. fig. 7 the sternum of Atrichia is figured with the 

 rudimentary clavicles (/), which are nothing more than granules 

 of bone. No other Passerine bird wants the furcula, so far as is yet 

 known. The' manubrium sterni is not largely expanded. 



There is another feature in Passerine anatomy which has interested 

 me considerably during my investigations. It is the rule among birds, 

 almost without exception, that the main artery of the leg is that 

 which must be supposed to be represented in Man by the comes 

 nervi ischiatici, it accompanying the sciatic nerve — the sciatic artery. 

 The main nerve of the leg is the sciatic ; the main vein the femoral. 

 The only known exceptions to this rule are the cases of the genus 

 Dacelo among the x\ Iced in idee, and Centropus among the Cuculidse. 

 In the former the femoral vein is replaced by the one which is in- 

 termediate in situation between its usual course and the sciatic artery ; 

 in the latter the sciatic artery is absent, and is replaced by the 

 femoral*. 



In a certain few Passerine birds the main artery of the leg is the 

 femoral, and not the sciatic. These genera are all members of the 

 Oligomyodi of Miiller ; and the accompanying list contains the 

 names of all the Oligomyodian species (taken from Messrs. Sclater 

 and Salvin's ' Nomenclator Avium Neotropicalium ' j* ) which I have 

 had the opportunity of examining, with the results arrived at, as far as 

 this peculiarity is concerned. 



* Proc. Zool. Soc. is?;:, p. 629. 

 t London. l*7.'l 



