"BWEARWISST- 
. 
BRITISH SPECIES OF THE GENUS MNIUM. 29 
it is possible to keep the measured parts in permanent microscopical 
preparations, glass tubes, etc. 
$19. (Continued from § 17.) PRACTICAL USE OF THE LIMIT VALUES.— 
Now we want to make a trial of the SECOND METHOD of identification by 
means of limit tables (see $ 16). We take a fertile stem a belonging toa 
patch æ. We measure merely three characters. The figures are :— 
Length of the longest leaf ................% . 615mm 
Breadth ,, i A aae A CIG es; 
E i m p Sat its basó, "os e 075 
We begin with Table XXV. (length): the minimum table excludes no 
species with certainty, the maximum table excludes serratum and perhaps 
orthorrhynchum. 
Table XXVI. (breadth): the minimum table excludes affine, punctatum, 
subglobosum, and perhaps rostratum and undulatum ; the maximum table does 
not exclude any species. 
Table XXVII. (breadth at the base): the minimum table excludes perhaps 
undulatum ; the maximum table excludes perhaps orthorrhynchum. 
By means of three measurements of stem @ we were enabled to exclude 
four species :—serratum, affine, punctatum, subglobosum, and perhaps three 
more species: rostratum, orthorrhynchum, and undulatum. 
We now take a second stem b of the same patch æ ; the figures are :— 
ength ofthe longest louie, M ese 6:92 mm. 
Breadth ., N Re yee S esr QT T. 
b "t Py een see Or; 
Table XXV. (length): no species are excluded by the minimum table, 
the maximum table excludes serratum (previously excluded) and confirms 
the exclusion of orthorrhynchum. 
Table XXVI. (breadth): the minimum table excludes cuspidatum, spinosum, 
afine (already excluded), punctatum (id. id.), subglobosum (id. id.), and 
confirms the exclusion of rostratum and undulatum. 
Nine species being excluded, it becomes useless to go further: the patch æ 
belongs to the species Mnium hornum *. 
Ewample of the use of limit tables according to the THIRD METHOD of 
identification: we take one stem æ with 43 leaves and measure four properties 
of the 5 leaves which belong to the 10th interval (see Table XIII. A). The 
figures are given in Table XIV. 
* It may be remarked that in this example it was possible to identify the patch v by 
measuring merely three properties of two leaves belonging to two stems, without taking into 
account any of the characters used in the classical books for the identification of Mnium 
hornum. 
