wee Ree ee ea. m s —""- * TA eu urit s 
BRITISH SPECIES OF THE GENUS MNIUM. 25 
Application of the third method is possible when the total number of leaves 
is greater than ten. 
TanLE XIII. A. 
Number of leaves in the tenth interval. (See the method of 
calculation in § 6.) 
Total number of leaves 
(from the lowest leaf Number of leaves 
to the longest one). in the tenth interval. 
Eoss than Ll... -. T IU MEER HK 1 
NA Ce. Bar oi UNT. 2 
eee DEUS n MUN eet ar 3 
PI MGS aE ge 4 
41-50 .....57.. ee ; 5 
etc etc. 
Example : The breadth of the leaves in the tenth interval is variable— 
In Mnium orthorrhynchum between 0:30 and 1:03 mm. 
In Mnium serratum » Doon 10r ays 
We want to discover to which of the two species belongs a stem s. 
The number of leaves is 19; in the tenth interval we find thus two leaves. 
The figures of those leaves are : 
Breadth : longest. leai m Oy urs 1:02 mm. 
B leaf below the longest one........ 120. 
The figure of the longest leaf is dubious, but the second figure (1:26) is 
decisive : « belongs to the species serratum*. 
$17. PRACTICAL USE OF THE LIMIT VALUES (continued).—I give in 
Part V. a certain number of tables of identification, in which are found 
the lowest and the highest value of the fourteen measured characters 
for the ten species of Mnium I have studied. The figures were obtained 
for each species by the measurement of specimens from as many localities 
as possible. 
Let us try to identify a specimen « belonging to one of the ten mentioned 
species. 
* It is possible to apply the third method to the identification of animals—for instance, 
of Beetles. A considerable difference may exist between the right and the left side ot one 
specimen with reference to certain characters; it may happen that a certain ligure is 
dubious at one side, the corresponding figure at the other side of the same specimen being 
decisive. 
