MICRODICTYON 135 
Microdictyon Dunkeri (Schenk). 
1870. Pecopteris decipiens, Trautschold, Nouv. Mém. Soc. Nat. Moscou, 
vol. iii p.' 29, pl. xix. fig. 6. 
1871. Laccopteris Dunkeri, Schenk, Paleontographica, xix. p. 219, pl. xxix. 
figs. 3-5. 
1874. Laccopteris Dunkeri, Schimper, Trait. pal. vég. vol. iii. p. 506. 
Piehavieen Deaton { Schenk, Palwontographica, xxi. p. 161. 
cree 53) della oq, thee, G10), 
Biemayon Bunkers) \. pi) erviii, Sesh lap 11d) ie 
1878. Laccopteris Dunkeri, Hosius and yon der Marck, Paleontographica, 
Xxvi. p. 208, xliv. fig. 192 and 193. 
1888. Laccopteris Dunkeri, Velenovsky, Abh. k. bohm. Ges. Wiss. p. 12, 
pl. il. figs. 3-7. 
1876. 
Type. Small pieces of leaves showing fertile segments. Originals 
in the Collections of Berlin and Gottingen. 
Schenk defines the species as: ‘‘folia . . . . ? segmenta pinnati- 
fida, lacinize e basi latiore lineares sinu lato rotundato remote 
integree patentissime obtuse basi 5-6 mm. lato, sori biseriales 
rotundi, sporangia receptaculo centrali affixa, nervi primarii validi, 
secundarii angulo acuto egredientes dichotomi, ramuli repetito- 
dichotomi.”’ 
In a later description of the same species Schenk expands this 
definition, and we may adopt his amplified diagnosis as affording 
an accurate description, so far as the imperfect material allows? :— 
Leaf-segments deeply pinnatifid, the lobes entire, at right angles 
to the rachis, linear, obtuse, approximate; midrib strong, secondary 
veins given off at a right angle, and forming large meshes which 
are occupied by a reticulum of smaller veins. 
Sori circular, in two rows, without indusia; sporangia eight to 
ten, vertical incomplete annulus; spores tetrahedral. 
The figure of Pecopteris decipiens, Traut., represents a small piece 
of a leaf-segment with the long straight divisions characteristic of 
Mierodictyon Dunkert (Schenk). Some of these show traces of the 
sori. There are no indications of any characters which would justify 
the retention of Trautschold’s species. The volume of the Nouv. 
‘ Mém. Soc. Nat. Moscou in which Trautschold’s paper is published 
has the date 1876, but the paper wrapper of a reprint in my 
1 Paleontographica, vol. xix. p. 219. 
2 Ibid. vol. xxiii. p. 161. 
