148 



PROCEEDINGS OF THE ACADEMY OF 



[Feb., 



shows a well-developed outer tooth in all but 5 specimens, which are 

 toothless; of the toothed forms a less well-developed inner tooth 

 appears in 38 specimens of the living form and 3 of the semi-fossil 

 form, while 36 of the living form and one of the semi-fossil form have 

 only the outer tooth. It will be seen, however, that the one-toothed 

 and two-toothed forms are about evenly divided in this colony. The 

 umbilicus. is closed in all specimens by an expansion of the lip. Average 

 dimensions are as follows: Width 20.4 mm.; height 36 mm.; mean 

 divergence 109°; average index .565. 



Fig. 9. — Garrett's Woods. 



4'he form of the shell in this race is like that from the Ridge near 

 Lincoln colony and somewhat higher in the spire than the shells from 

 Somerset Road, but there are a great many small shells with very 

 high spire. This is natural, for a large number of the specimens 

 were taken from the hill-top, and, as at Somerset, so here, the hill-top 

 forms run smaller than those found lower clown on the slopes. The 

 four semi-fossil forms are uniformly larger than the others, fig. 9, 

 w T here the four highest shells are semi-fossil, and in these there is a slight 

 concavity next to the periphery above in the last whorl. They 

 probably represent the original race that reached this locality in the 

 migration of the species, and that was subsequently modified to the 



