A STUDY OF THE NASAL BRIDGE IN THE ANTHROPOID 
APES AND ITS RELATIONSHIP TO THE NASAL BRIDGE 
IN MAN. 
By KATHLEEN V. RYLEY, Crewdson-Benington Student in Craniometry 
and JULIA BELL, M.A., assisted by KARL PEARSON, F.R.S. 
CONTENTS. 
PAGE 
(1) Introductory : Nature of Material and Measurements made ...... 391 
(2) Reliability of Measurements : Effect of Personal Equation in Sexing, of Secular Change 
in Personal Equation of Measurer and of Differences in small Samples . . 393 
(3) On the Observed and Calculated Values of the Subtense Mesodacryal Index. The Catenary 
Hypothesis .............. 393 
(4) On the Simotic and Mesodacryal Indices. Their Relative Evolutionary Value . . 401 
(5) On the Absolute Nasal Measurements .......... 405 
(6) On the Absolute Mesodacryal Measurements ......... 407 
(7) On the relative Racial Variability of the Nasal Bridge Characters. Sexual Differences 
in Variability 409 
(8) Racial Relationship as based on Nasal Bridge Measurements. Ancestral Tree . . 417 
(9) On the Correlations of the Nasal Bridge Characters ....... 418 
(10) The Maxillary and Simotic Nasal Angles, </> and <p' '. The Inter-relationships of Anatomical 420 
Units 
(11) General Classification of Nasal Bridges by aid of Angles <p and <f>' . Homoclinic and 
Heteroclinic Nasal Bridges. Measurements of Simosis and Gephyrosis. Contoms 
of the Nasal Bridge 420 
(12) Discussion of Projections of Nasal and Maxillary Portions of Nose on Base of Nasal Bridge 430 
(13) Concluding Remarks ............. 435 
(1) Introductory. 
The measurements on which the following paper is based were taken by 
Kathleen V. Ryley, in part at the Museum of the Royal College of Surgeons by 
the kindness of Professor Arthur Keith ; in part at the British Museum (Natural 
History), where we have especially to thank Mr W. P. Pycraft; in part at the 
Cambridge Anatomical Museum and in the private collection of Dr Duckworth, whom 
we have heartily to thank for his courteous and ready aid ; in part at the Oxford 
Museum by the kindness of Professor Bourne. Lastly we owe the possibility of 
measuring a few specimens to Professors Thane and Hill of University College, 
London, who readily placed their material at our disposal. We have further to 
express our indebtedness to Professor Thane and to Dr Derry for aid in a variety 
of other ways. Only by the great help received from all these authorities would 
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