Luwer Silurian.] PALAEONTOLOGY OF VICTORLV. [Graptatites. 



indenting- the branch § of (or rarely onlj- ^) its width, the lower boundary line of 

 eacli cell reaching- the back at a point opposite the next lower cell point in the 

 deeply indented examples, but reaches nearly to the next further one in others; lower 

 marg-in straight, upper margin slightly convex, points in most specimens only slightly 

 acute and not mucronate, and not recurved in any examples seen. 

 Reference.— (Hall), Can. Org-. Rem., dec. 2, p. 96, t. 7-8. 



None of our sjiecimens are so broad as many of the Canadian 

 ones, but the number of denticles in a given space is usually the 

 same at an inch or more from the base, and some of the Canadian 

 specunens of this species are as narrow as the Australian ones, and 

 the greater proportionate indentation and less obliquity of the cells 

 agrees with the narrower American specimens, though seeming to 

 differ from the broader ones ; it is prol3able that the diversity is due 

 only to a difference in the direction of the pressure the individuals 

 were subjected to. Some of the specimens have 8 denticles in 3 

 lines close to the base, though only 6 or the nonnal Ameiican 

 number of 5 on more distal parts of the Ijranch. 



Some specimens seem to have only 7 branches, from 1 of the 4 

 primaries apparently not dividing. 



Common in the whitish slates, B" 78, Barker street, Castle- 

 mame ; common in the black Llandeilo flags of B" 43, Watchbox 

 Range, Gleuhope, and Piper's Creek, sheet 51 S.W. ; in the olive 

 slates of B"* 71, on the east bank of the Saltwater River, 1 mile 

 from the Bacchus Marsh road ; B" 39; B" 27; B" 28; B'' 2. 



Explanation of Ftoures. 



Plate II. — rig. 4, specimen, natural size. Fig. 4fl, portion of polj-pidom magnifieil to shuw 

 form of colla. 



Platk 11., Fig. 6. 



GRAPTOLITES (DIDYMOGRAPSUS) LOGANI (Hall). 

 Var. AUSTRALIS (McCoy). 



Description. — Vinculum rather more than 1 line long with a short radicle 

 or mucro in the middle. At each end of the vinculum 2 branches extend diverging 

 at about 100° from each other, and rather shorter than the vinculum, each 



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