1911.] 



NATURAL SCIENCES OF PHILADELPHIA. 



133 



inclusive, 18 (or 60 per cent, of the whole series from Somerset meas- 

 ured) have an index between .78 and .80. From the Ridge near 

 Lincoln colony the range in the index is from .78 to .83; of the 16 

 examined 4 (or 25 per cent.) were below .79, 6 (or 37^ per cent.) 

 ran between .79 and .80, and a like number were above .80, and of 

 these, 4 (25 per cent.) were above .82. 



The few scattering specimens collected at the other localities men- 

 tioned are all larger than the majority of the Garrett's woods suite, 

 but the index is very variable, ranging in the Benmore suite from 

 .73 to .80 in six examples. 



Fig. 2.— P. jamaicensis. Garrett's Woods and Somerset Colonies. 



A comparison of the forms from the Garrett's woods colony with 

 those of the Somerset and Ridge near Lincoln colonies may be made 

 by examining figs. 1 and 2, which are plotted from the measurements 

 of height and width. From these figures the relative variations can 

 be readily seen. Averaging all the measurements gives about the 

 following : 



