90 
The Irish Naturalist. 
April, 
squares, we have a series of numbers and dashes which present 
no difficulty to the compositor ; and the distribution of Ciaita 
virosa, a characteristically north-eastern species with a con- 
tinuous range, as shown by this method, appears below, heavy- 
face type being used for the divisions in which it is present : — 
35 34 40 -- 39 
36 
- 33 - 37 38 - 
— 27 - 28 29 30 32 
- 26 - 25 24 - 31 
- 16 — 17 23 22 ~ 
— 15 — 18 — 19 21 
_ 9 —10 — 14 — 20 
— 8 — 7 — 11 13 — 
— 1 4 5 6 
Fig. 3. — Distribution of Ciciita virosa."^ 
A disadvantage attaches, however, to this plan : the effect 
of the padding of blank squares (while it preserves the pro- 
portions ol the diagram) is to exaggerate the area from which 
a plant is absent, and to obscure a continuous range. Any 
further condensation of the figure results of necessity in loss 
of accuracy as regards relative position of the division- 
numbers, yet the following development appears advantageous 
for the reason stated. We eliminate the blanks by pushing 
the numbers together horizontally ; and then restore the 
general proportions of the figure by omitting the horizontal 
lines in which "36" and ''2 . . . 12" stand alone, trans- 
ferring these figures into the adjoining lines. The result is a 
compact figure as shown in figure 4 :~ 
^ Since the map (fig. i) was constructed, Cicuta has been added to 
28 (Sligo). 
