362 ABSTRACTS OF PAPERS. [VOL. II. 



found for measuring these quantities. A special instrument is 

 being constructed which, it is hoped, will overcome the difficulty 

 in regard to thickness. 



A preliminary study of the shells from Eastport and Glouces- 

 ter shows that for characters (i) to (4) the variations may be 

 represented by curves that are approximately normal. The 

 curves for the two stations at Eastport fit together pretty 

 closely ; while they differ distinctly from the curves for the 

 Gloucester specimens, the difference of the means being 

 greater than the standard deviation for each locality. In 

 each case the female shells showed, on the average, a wider 

 angle and a shorter spire expressed in per cent of total length, 

 than the corresponding males, and the same is true for the 

 Gloucester shells as a whole compared with the Eastport 

 shells. 



As a measure of variability the coefficient of variation 



f cv. 100 ] gives contradictory results and appears not to 



\ m J ' 



be applicable to measurements expressed in degrees of a circle. 



Judging from the standard deviations, the shells from Gloucester 

 are somewhat more variable than those from Eastport. The 

 relative variability of the males and females differs for the 

 different characters, and for the same characters in different 

 localities. In general, the females appear to be slightly more 

 variable than the males. 



XXVI. VARIATION AND ELIMINATION IN 

 PHILOSAMIA CYNTHIA. 



HENRY E. CRAMPTON. 



SOME of the results were presented of a statistical study in 

 the case of a large Saturnid moth, P. cynthia, of the variability 

 of eliminated and surviving pupae and imagines. From a lot 

 of nearly 1 100 cocoons, only 310 living pupae were obtained; 

 632 contained dead pupae; while the remainder were shriveled 

 or otherwise abnormal larvae or pupae. The living pupae were 

 compared with an equal number of dead pupae with reference 



