Page:Proceedings of the Royal Society of London Vol 60.djvu/254

Rh inclined at tan"1 r to the axis of x. The ends of the lines are irregular on account of the impossibility of obtaining a satisfactory {mean to the relative at these points because of the paucity of individuals near the limits of the range of deviation. One sees that, in these two cases at least, the correlation surfaces must closely approximate to the symmetrical normal surface.

Carcinus moenas. Naples race. Carcinus moenas. Plymouth race. Portunus depurator. Plymouth. Organs. r. Probable error of r. r. Probable error of r. r. Probable error of r. Total breadth and frontal breadth ........................... 0-08 0-0211 o -io 0-0210 0 T 4 0 -0305 antero-lat.. •. . *............. 0*66 0 -oioo 0-65 0 *0103 0-67 0-0082 Total breadth and It. dentary........................... 0*50 0-0143 0-55 0 -0130 0-56 0 -0107 Frontal breadth and It. antero-lat....................... 0-29 0 -0187 0-24 0 *0195 0-30 0 -0270 Frontal breadth and R. v dentary........ . ............... -0 -2 3 0-0197 -0 -1 8 0 -0203 - 0 -0 3 0 -0314 Frontal breadth and L. dentary........................... -0 -2 6 0-0193 -0 -2 0 0 -0201 - o - o i 0-0314 K. antero-lat. and L. antero-lat........................ 0-76 0 -0072 0-78 0 -0066 0-86 0 -0035 It. antero-lat. and It. dentary........................... 0-71 0-0086 0-78 0 '0066 0-80 0-0050 It. antero-lat. and L. dentary.......... ................ 0-60 0-0117 0-70 0 -0089 0-74 0-0065
 * Total breadth and It.

In the above table the 2nd and 4th columns give the values of Gal ton’s functions which Professor Weldon found for two races of female Carcinus moenas (‘Roy. Soc. Proc.,’ vol. 54). The sixth column gives the values of r obtained for Portunus. It is quite obvious that there is a marked similarity between the three columns of figures. The probable errors of r were found by 1—r2 the formula 06745 ; — which Professor Pearson shows will V n{\ + r2)’ give a close approximation (‘ Phil. Trans.,’ vol. 187). These probable errors were added to indicate how far the differences in the values of r are to be regarded as meaning actual deviations in the constants. The values obtained for the two races of Carcinus differ from one another nearly as much as they do from the constants of Portunus. We have thus proved that the mutual relationships of the organs measured are almost as closely similar between the two genera Portu-