Lower Silurian.] PALAEONTOLOGY OF VICTORIA. [Graptolites. 



to be squarely notched put of the side margins. The only specimen 

 of D. bicornis I have seen in Australia is 1 inch long, 1^ lines wide, 

 5 cells in a space of 3 lines, and a distinctly bicornute base, but 

 being compressed at right angles to the usual i)lane, I cannot 

 describe it fully. 



In the black flags of B'' 62. 



Explanation of Figure. 

 Plate I. — Fig. 8, specimen, natural size. 



Plate I., Figs. 9-14. 



GRAPTOLITES (DIDYMOGRAPSUS) FRUTICOSUS 



(Hall sp.). 



[Genus GRAPTOLITES (Lin.). (Class Zoophyta. Order Hydi-ozoa. Fam. Graptolitidse.) 



Gen. Char. — Polypidom horny, elongate, compressed, with a slender solid axis along one 



edge, followed by a parallel common longitudinal canal, from which one close row of cells 



extends, each inclined upwards and outwards, and all terminating in separate apertures on the 



serrated edge opposite the solid axis.] 



[Sub-yenera.- — 1. Graplolites (proper). Stem single and simple; Upper and Lower 

 Silurian. — 2. Didi/mograpsus (McCoy). Stems simple, but united in groups of two or more 

 by the pointed uncelled lower end. Some of these have a round horny disc, connecting the 

 non-celluliferous bases of the grouped stems ; Lower Silurian. Some writers divide the 

 species into sub-genera Tetragraptus, Loganograptus, &c., according to the nimiber of stems 

 conjoined, a character certainly not of generic value.] 



Description. — Polypidom composed of 4 sigmoidally curved stipes, usually 

 about 1 inch long-, diverg'ing- in pairs, with elegant bell-shaped outlines from 2 short 

 branches which diverg-e at an angle of about 40° from the summit of a straight non- 

 celluliferous slender radicle about 6 lines long. Each stipe gradually increases in 

 width from its slender base nearly to the upper extremity, to which the last 2 or 3 

 cells diminish so much in length as to form an abrupt rounding towards the outward 

 curved apex. Cells on the inner edge of each pair of branches very large, aperture 

 very wide, forming a large moderately acute angular denticle, the angle of which 

 diminishes graduallj' from the base to the apex, being about 35° in middle (about 4 

 to 5 in 3 lines near middle of stem), nearly half of the length uncovered by next 

 lower cell. Surface smooth, substance very thin and delicate. 



Reference.— (Hall), Geol. Sur. C. D., 2, t. 5, figs. 6-8; t. 6, figs. 1-3. 



This is the first Victorian Graptolite I ever saw, and, as it was 

 then a new species, I had named it in my MSS. after Mr. J. A. 

 Panton, who had found it in the soft shales of Bendigo, of which 

 goldfield he was then Warden, and in whose hospitable camp I was 



[ 13 ] 



