OF THE FORTY-NINTH PARALLEL OF LATITUDE. 15 
species of the genus Trichostomum allied to T. flavovirens in 
respect of Tortula: taking for the typical species T. tortuosa, the 
only difference is in the shorter teeth of the peristome, the 
structure being identical. The same analogies exist in the 
` development of the peristome of the pleurocarpous mosses, as, 
for example, in the capsule and peristome of the so-called genera 
Homalothecium and Camptothecium. In the species contained in 
these genera, the resemblance between the plants without the 
fruit is so great that it requires an expert bryologist to distin- 
guish them from each other. The same is the case with Pylaiesia, 
which without fruit or inflorescence could hardly be known from 
Hypnum cupressiforme. It would seem, therefore, that a natural 
group of Mosses can only be defined from the structure of the 
species in which the highest development is found. All those 
species which agree in all other respects, as habit, ramification, 
position of the fruit, form, and substance of the leaves, but pre- 
sent a less development of peristome, should be considered as only 
affording a negative difference, of barely specific value. There 
would appear to be no escape from this conclusion among the acro- 
carpous genera; and as there is no difference in the structure of 
the peristome in the pleurocarpous, it must be applicable to the 
whole group of Arthrodontoid mosses. 
MUSCI. 
DICRANACEA, Mitten, Musci Ind. 
CxNopoxTIUM, Hedw. 
(Distichium, B. et S.) 
C. cAPILLACEUM, Hedw. 
Hab. Near Fort Ellice, Saskatchewan, and Rocky Mountains, Bourgeau; 
Cascade Mountains, Lyall. 
C. INCLINATUM, Hedw. 
Hab. Saskatchewan, Bourgeau. 
(Leptotrichum, Hampe.) 
C. FLEXICAULE, Schw. 
Hab. Cascade Mountains, Lyall. 
(Dicranella, Schimp.) 
C. crispuM, (Dicranum) Hedw. 
Had. Galton Mountains, Lyall. 
C. SUBULATUM, (Dicranum) Hedw. 
Hab. Galton Mountains, Lyall. 
