Silurian.) PALAONTOLOGY OF VICTORIA. [ Graptolites. 
doubtfully referred this species to Didymograpsus as having single- 
round celluliferous simple stems arising from a common non- 
celluliferous stipe, yet the unusual form of the growth would 
warrant another sub-genus being established for it. 
Rare in the black flags of the Bala rock (B* 62), N.W. of Bulla 
EXPLANATION OF FIGURE. 
Plate XX.—Fig. 9, large specimen, natural size ; the ruggedness of the branches indicates 
slightly the place of the cells, but they are so minute and the rock so rough that a satisfactory 
magnified view could not be drawn. 
Pirate XX., Fia. 10. 
RETIOLITES AUSTRALIS (McCoy). 
[Genus RETIOLITES, formerly GLADIOLITES (Barranve). (Class Zoophyta. Order 
Hydroida. Fam. Graptolitide.) S 
Gen. Char.—Polypidom flat, parallel-sided above, tapering to the base, with two rows of 
cells in one plane alternating with each other, extending obliquely upwards and outwards to the 
margin on which they open; no central axis; surface covered with a prominent calcareous net- 
work. The reticulated surface and want of central axis separate this genus from Diplograpsus. ] 
DEscriIpTIoN.—Stem nearly parallel-sided, semi-elliptically tapering at base, 
about 13 lines wide and upwards of 7 lines long; strong boundary lines between the 
cells, nearly straight, making an angle of 55° with the lateral margin, the length of 
each cell being about double its width; the lower boundary of each cell is extended 
in a short slender spine at right-angles a little beyond the margin. Whole surface 
reticulated with slender flexuous anastomosing prominent thread-like ridges, and a 
small square slightly elevated granulation ; about 7 cell-points in a space of 2 lines 
at the margin. 
This species is most nearly allied to the Gladiolites or Retiolites 
Geinitzianus of Barrande from the base of the Upper Silurian 
strata of Bohemia, but is very much smaller, and has nearly double 
the number of cells in the space of 2 lines at the margin that that 
species has. 
The occurence of this extraordinary genus of Upper Silurian 
Graptolites in the Australian beds of the same age is very interest- 
ing, considering the rarity of species of the genus elsewhere. 
[ 36 ] 
