ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 309 



and hypertrophic for that; neither can this be the case with the 

 antlers of most deer or the horns of numerous antelopes, cattle, sheep, 

 and goats ; on the other hand the structures in question wear to a very 

 high degree the character of sex-features, "in their exuberance^ 

 unpractical build, curious complication, obviousness and variability." 

 But the author cannot agree with Bolsche that the growths on the roof 

 of the skull are purely ornamental exuberances of growth, and connected 

 with a regression of the ensiform tusks of the male. J. A. T. 



Mandible of Birds. — N. G. Lebedinsky (Revue Suisse Zool, 1918, 

 26, 129-46, 6 tigs,). A discussion of a number of points — the paired 

 primordia of the dentary in nine orders (as in other vertebrates), the 

 proportions of the various regions in the lower jaw, the reduction of 

 the pars anterior in parrots and some other types, and the relation of 

 particular features to the conditions of life. J. A. T. 



Increasing Number of Ostrich Plumes. — J. E. Duerden {Bull. 

 Defpt. Agric. Pretoria, 1918, No. 7, 1-39, 12 figs.). The first-row 

 feathers on each wing vary from 33 to 39, the mean being 36*54. The 

 ostriches of the whole of Africa seem to produce the same average 

 number of plumes. During fifty years of ostrich farming no advance 

 in the number has been made. The breeding has been for quality, not 

 "quantity. Of late two 42-plumed birds have occurred. One of these 

 survived and bred true. On the whole the wings of the ostrich have 

 undergone degeneration as regards number of feathers. The third 

 finger (which has no claw as is sometimes alleged) is almost buried in 

 the flesh. The 42-plumed wing is regarded as a survivor of an ancestral 

 condition. It appears that the factors for quantity do not interfere 

 with those for quality. From the 42-plumed strain it may be possible 

 to raise a stock giving the same quantity of feathers from three-quarters 

 of the number. J. A. T. 



Phylogeny of Jaw Muscles in Vertebrata. — L. A. Adams {Ann. 

 New York Acad. Sci,, 1919, 28, 51-166, 13 pis.). The two chief 

 muscle masses of the jaw — {a) the adductor mass innervated by the ramus 

 mandibularis of the fifth nerve, and {h) the depressor or digastric mass 

 innervated by the facial — are homologous throughout the Vertebrata. 

 The adductor of the fish type is the mother mass from which the muscles 

 of mastication are derived throughout the vertebrates, by the separation 

 of slips of this muscle and by their gradual complete separation in nerve 

 supply through the growth of the originally small twigs into separate 

 nerve branches. In a very interesting way the author traces the evolu- 

 tion of new slips, such as the so-called pterygoid muscles, and brings 

 them into correlation with the changes in the skull, e.g. in the temporal 

 fenestra and the quadrate. J. A. T. 



Comparative Study of Pelvic Muscles. — S. Nishi {Arbeit. Anat. Inst. 

 Japan, Univ. Sendai, 1919, 3, 1-72, 21 figs.). A study of the differen- 

 tiation of muscles in the region of the exitus pelvis. Beginning with 

 the early differentiation in the pelvic region of fishes, the author traces 

 the differentiation of M. subvertebralis pelvus, M. obliquus pelvis, M. 



