ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 743 



chief part of the malleus arises. The malleus as a whole is a gonio- 

 articular. 



One of the general characteristics of the gonial is its close topo- 

 graphical relation to the chorda tympani, which often penetrates into 

 the canalis primordialis of the embryonic lower jaw. This is retained in 

 some mammals in the perforation of the processus anterior mallei. 



In mammals, as contrasted with reptiles, the posterior toothless por- 

 tion of the jaw gets separated off and goes into the service of the ear 

 (articular + gonial = malleus ; angular = tympanic, and quadrate 

 = incus). The anterior part acquires a new connexion with the 

 squamosal, forming the " secondary " articulation of mammals. This is 

 exclusively a squamoso-dentary articulation (formed between two bones 

 not previously in association) and is not shared in by components of the 

 old quadrato-articular joint. 



The " ramus " of the mammalian lower jaw is probably referable to 

 the processus ascendens of the reptile dentary, which differentiates into 

 a condyloid and a coronoid portion. The probable history of the 

 establishment of the characteristic mammalian squamoso-dentary articu- 

 lation in front of the old quadrato-articular joint is discussed in detail. 



Origin of Domestic Dog.* — E. L. Trouessart revives and corrobor- 

 ates a view suggested in 1877 by Jeitteles that the ancestor of domestic 

 dogs is to be found in the small Indian wolf, Ganis pallipes Sykes, which 

 has a well-marked supra-orbital crest. The only exception he will admit 

 is that of the dogs of Ancient Egypt, recently discovered by Hilzheimer 

 and by Gaillard and Lortet, which seem to have been derived from 

 several species of jackal. The author cannot agree with Studer's con- 

 clusion that the domestic dog is descended from a European species 

 which became extinct in Quaternary times. 



Reproductive Organs of Domestic Animals.f — E. Schmaltz has 

 given a monographic account — both anatomical and histological — of the 

 reproductive organs of horse, ox, sheep, pig, dog, and cat. 



Mobility of Penguin's Vertebral Column.J — Hans Virchow has 

 made a study of the freedom of movement in the vertebral column of 

 the penguin (Spheniscus) — a mobility familiar enough to those who 

 have watched the birds in zoological gardens, but emphasized in recent 

 years by the photographs of various Antarctic explorers. The author 

 analyses the different possibilities, but shows that, as far as structure 

 goes, there is not much difference as one would expect beween the 

 penguins and other birds. The difference is not so much in the 

 apparatus as in the way in which it is used. 



Migration of Birds. § — A. Landsborough Thomson discusses the 

 possibilities and actual results of bird-marking (by means of aluminium 

 rings bearing a number and address), with a view to discovering 

 additional facts in regard to migration. He gives an historical note on 



* Comptes Rendus, clii. (1911) pp. 909-13 (2 figs.). 



t Die Struktur der Geschlechtsorgane der Haussaugetiere. Berlin : (1911) 

 xii. and 388 pp. (168 figs.). 



t SB Ges. Nat. Freunde Berlin (1910) pp. 4-10 (6 figs.). 

 § Proc. R Phys. Soc., xviii. (1911) pp. 204-18. 



