120 The Danvers Bowlder. 



chum Pmnsylvanicum. Hedvv. Sp. Muse. t. 24. Sulliv. 

 in Gr. 1. c. 



One of the smallest of the polytrichacese, and not unfa- 

 miliar to any one, who has been attracted by the habits of 

 some of the mosses, that delight to grow on moist slopes of 

 sandy or clayey soils. Its stems rise from a flat tissue of 

 green, closely compacted filaments. On their summits are 

 a few crowded and appressed, somewhat denticulate leaves. 

 It is specified incorrectly, as a new species in a previous 

 number of this Journal, on page 92, line 20, where it may 

 be erased and the true name substituted. 



6. ATRICHUM ANGUSTATUM (BEAUVAIS.) Sulliv. inGr. 1. c. 

 Catharinea angustata. Brid. Bry. II. 105. Polytrichwn 

 angustatum. Hooker; Muse. Exot. t. 50. 



The leaves of this pretty moss are thin, delicate and in- 

 clined to curl inwards at their tips, suggesting the specific 

 name on the 92d page of No. II. of this Journal where, erase 

 the 4th line. The description there found, refers to the 

 name and synonyms at the head of this paragraph, and the 

 plant in question has also, no particular affinity with " Po- 

 lytrichum lacvigatum of Wahlenburg," which is exclusicely 

 a species of high northern latitudes. 



The Atrichum angustatum may be seen in thin, grassy, 

 and moist places under trees, or in spots wherever shade 

 and moisture prevail. 



THE DANVERS BOWLDER, or Ship Rock. 



The phenomena of bowlders have been considered the 

 most instructive index we possess of a powerful diluvial 

 agency. They are found in great numbers throughout the 

 whole extent of Massachusetts, are usually somewhat 

 rounded in outline, and are rendered quite smooth by attri- 

 tion or by atmospherical agency. 



