20 



archegonia and a compound microscope will be necessar\- to make 

 out most of the following points: 



If after remoxing the operculum we examine the mouth of the 

 capsule under a low power we shall find it to be surrounded by a 

 row of 64 teeth; this row of teeth is called the peristome. The 

 points of the teeth are lightly attached to a membrane stretched 

 across the mouth of the spore case. Under the compound micro- 

 scope the leaves appear lanceolate and sharply serrate with a 

 clasping base made up of large, nearly colorless cells, while the 

 upper part of the leaf is much more dense, and is deep green. The 

 midrib or costa is very broad and consists of several layers of cells 

 while the margin consists of a single layer. In order to increase 

 the light-receiving area this plant has adopted the curious contriv- 

 ance of sending out from the upper surface of the costa radiating 

 layers, lamellae, a single cell thick. These are shown in a cross 

 section of the leaf at fig. 1 o. The upper cell in this species is concave 

 on its upper edge, as is shown in the greatly magnified lamellae 

 at fig. 9. 



There are six species of Polytrichum which occur in New 

 England. The most common species next to P. commune is P. 

 piliferum Schreb., Awned Hair-cap Moss, which grows in dry 

 situations around ledges and gravelly places. It is much smaller 

 and is readily determined by the long slender awns at the apex of 

 the leaves. I have collected this on the very brow of The Profile, 

 Franconia Mountains. P. juniperinum Willd, Juniper-like Hair- 

 cap Moss is also common in woods or peat bogs and is easily dis- 

 tinguished by its lighter color and the incurved margins of the 

 leaves. If you climb any of the higher mountains you are sure in 

 moist places to find P. strictum Banks, the Erect Hair-cap Moss. 

 This is distinguished from all our other species by the dense felt of 

 radicles which sometimes covers nearly the entire plant, and from 

 P. juniperinum, of which it was formerly reckoned a variety, by the 

 erect appressed leaves and cubical capsules. The three species 

 last named have entire leaves. The only other species likely to 

 be met with is P. Ohioense, Ren. and Card., Ohio Hair-cap Moss. 

 This has serrate leaves and is not always readily distinguished 

 from P. commune by an inexperienced observer. P. commune 

 has the capsule cubical and entirely covered by the calyptra, while 

 in P. Ohioense the capsule tapers into the seta and is not quite 

 covered by the calyptra. 



While the limited supply lasts specimens of P. commune. P. strictum. P. 

 juniperinum and P. piliferum will be sent to any subscriber upon receipt of ten 

 rents in stamps. 



