214 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



sufficiently valuable to Justify a conclusiou. ' Indeed, if we rightly interpret the spirit of previous 

 writers upon the subject, we should be inclined to believe that the series of Europeans given 

 above is the only series large enough to be of undoubted value. 

 Broca* says: 



* * * There is but a very slight difference between the human average and the averages of the great anthro- 

 poids, u diflerence so feeble that it disappears often when one considers, instead of the averages, the individual 

 cases. 



§ 30. TORSION OF THE HUMERUS. 



Notwithstanding the opinion of Topinard, that the angle of torsion of the humerus gives '• a 

 good zoologic character and a bad anthropologic character," t we have determined it iu all the 

 humeri of this collection (41 in number), in which the necessary guiding marks as laid down by 

 Brocaf were found intact. Of this number 21 were from the right side and 20 from the left; but 



there were only 15 complete pairs. Of the lat- 

 ter G pertained to female skeletons, 5 to male 

 skeletons, and 4 to skeletons of undetermined 

 sex. Of 6 right unpaired humeri 2 were male 

 and 4 of undetermined sex. Of 5 left unpaired 

 humeri 1 was male and 4 of undetermined sex. 

 The degree of torsion was ascertained by 

 a graphic system analogous to that employed 

 by Lucae and Welcker,§ but by means of an 

 apparatus different to theirs, which was devised 

 by Dr. J. C. McConnell, of the Army Medical 

 Museum, and is shown in Fig. 44. 



It is a modification of the apparatus men- 

 tioned in § 3 and illustrated in Pig. 23. The 

 periglypli (Fig. 24) is employed and the tracings 

 are taken on varnished glass, inked and trans- 

 ferred to paper in the manner described in § 3. 

 The frame («, a, a) is much the same in both 

 apparatus; but in the one now under consider- 

 ation we have iu the center of the frame a 

 revolving stage with a clamp for holding the 

 humerus. 



Four long distinct parallel lines are drawn 

 on the stage at right angles with its axis — one 

 on each side of the clamp — on both the upper 

 and lower surfaces, those on one surface being 

 exactly vertical to those on the other. 

 The angle of torsion is obtained iu the following manner: Indicate on the humerus the axial 

 lines of its two extremities. Secure the bone in a vertical position at the middle of the shaft by 

 means of the clamp, let us say with the head of the humerus upwards at first ; make a tracing of 

 the head by means of the periglyph (c) on the varnished glass [d), being careful to include a 

 tracing of the axial line and the parallel lines drawn on the stage. Invert the stage by turning 

 it on its axle, inverting at the same time the bone and bringing the lower surface close to the 

 varnished glass, where the outline with the axial and parallel lines may be sketched with the 

 periglyph as before; ink the tracings and transfer to the paper in the manner described in § 3. 



Fig. 44. — Apparatus fordeterminmg 



* P. Broca : Indices de Largeur de Tomoplate. Bulletins de la Soci6t6 d'Anthropologie, Paris, 1878, p. 77. 

 t Op. cit., p. 1048. 



t La torsion de I'hnmerus. Revue d'Anthropologie, Paris, 1881. T. 2 serie, pp. 389 ct seq. 



4 Lucae : Die Stellung des Humeruskopfes zum EUenbogengelenk beim Europiier and Neger, in Archiv fur 

 Anthropologie, 18(itj, i, i>. 237 et eeq. 



