AND RETICULATIONS OF THE R-GON. 208 
is therefore necessary to substract those triply reversibles, 
and then to divide by two, for the reason given in the six- 
teenth article. 
The formule which have to be corrected in consequence 
in Art. 25 are (16), (19), (22) and (23). The reader will 
kindly alter them to the following : 
(16). PR?(4v+m+1,2a) = R?(4x + 1,22) 
oe 27-21 ie a—-2|1) 
x1" z+1) oe coe) a 
[zn =" ‘ j|1,,__ 
(19). IR?(40 + m+ 1,2v) = R*(42 + 1,22) 
m x—2|1 
x gn-2 Coach < (G+1) 
2Qr—2|1 m 2e—3 | 1 
a (F+1 ) nm xt) 
pease to A oe (a 
1 Qx—2 $1 
or Gg j 
i ee 
(22). I3R3(67 +m +1,82) = R4(6x + 1,32) 
2x2 | I v—2|1 
GH) ee GH) weed 
er a 
(23). IR%(6x7+m+1,3x) =4R5(6x + 1,32) 
™m 
™ =+l1 
x a i (m+ 1)%-#! 495 (é ) 
[est oy ae 
m 3a—3 | 1 m 2—2 | 1 
ae Gay as GH) 
; Co a ae 5 5 
The formule of Art. 25 thus corrected, together with 
those of Art. 26, are all that are required for the enumera- 
tion of the triangular partitions of the 7-gon for all values 
of *. 
