THE NAUTILUS. 



Fig. 3. Acmaea alveus (Conrad). Normal radula. Developing 

 teeth of the posterior portion of the same radula as Fig. 2. These 

 teeth have little or no coloring. Lettering the same. 



Fig. 4. Acmaea alveus (Conrad). Abnormal radula. L, lateral ; 

 C, central ; U, outermost ; A, additional teeth. 



PULMONATE8 OF THE MATINICU8 ISLANDS, MAINE. 



ARTHUR H. NORTON. 



The Matinicus Islands form a group of off-shore islands outside of 

 Penobscot Bay. They constitute the most isolated land mass of any 

 size in the state, their nearest point of approach to the mainland 

 being thirteen nautical miles. In the group there are eight islands, 

 seven dry and numerous half-tide and sunken ledges. The total 

 acreage I have roughly estimated at about fifteen hundred acres. 



Matinicus is the largest of the group, containing about eight hun- 

 dred acres. It is quite well wooded and diversified in topographical 

 features. Exploration of this island would doubtless increase the 

 following list materially. 



Seal Island lies six miles east of Matinicus harbor, and Matinicus 

 Rock five miles south of the harbor, both forming isolated points of 

 great exposure and long separation. 



Several plants are found in abundance on these two points which 

 are nowhere else abundant on this coast west of Petit-Menan point. 

 Both are destitute of trees. As would be expected from their long 

 isolation and great exposure, they are completely " rock bound," in 

 fact, enormous ledges, with their valleys and seams filled with soil, 

 which is partly coarse gravel, deeply overlaid with decayed vegeta- 

 tion, and everywhere strewn with fragments of rock, rent by frost 

 and the action of time, or hurled by the fury of unusually severe 

 storms. 



The southwestern exposures of both are bluffs dropping immediately 

 into water of considerable depth. At the rock, the history of which 

 has been made known through the medium of the light-house estab- 

 lishment, the surges generated by gales from the southeast not in- 

 frequently break over the island notwithstanding the fact that it is 

 about fifty feet above mean high-water mark. 



