Lower Siluriiin.'] PALiEONTOLOGY OF VICTORIA. IGraploUUs. 



Plate I., Fios. 1-4. 



PHYLLOGRAPTUS FOLIUM (His. sp.)- 

 Var. TYPUS (Hall). 



[Genus PHYLLOGRAPTUS (Hall). (Class Zoophyta. Order Hydroida. Fam. Grap- 

 tolitids.) 



Gen. Char. — Polypidom composed of 4 semi-cUiptical flat laminae, united by the straight 

 edge at right angles to each other -, each lamina composed of tubular cells extending upwards 

 and outwards from the straight inner edge to open on the convex outer edge. Confined to 

 Lower Silurian or Cambrian rocks.] 



Description. — Polypidom petaloid, either broad oval or broad ovate, with 

 the basal end often broader or rarely narrower than the apex, or very elongate 

 elliptical, tapering- to both ends, or with straight parallel sides and obtusely rounded 

 ends ; ordinary length about 10 lines, with a width varying from J to | of the length. 

 Midrib or axis varying from narrow and linear to excessively thick, about 1 line 

 wide in specimens of ordinary size, J line wide in young individuals of 3 lines long, 

 and from 1| to 2 lines wide in large specimens of \\ inches long, according to the 

 direction of compression. Cells gently arched outwards and downwards towards the 

 distal end, the chord of the arc forming an angle of about 70° with the axis in the 

 greater part of the length, but gradually becoming more erect at an angle of 40° 

 towards the ajiex of the polypidom, and exceeding a right angle in the downward 

 inclination towards the base. Mouth of each cell with a concave outline slightly 

 extended obliquely towards the lower point, but nearly at right angles with the 

 upper and lower boundaries, which are produced into slender, straight, or downward 

 curved points, about equalling or slightly exceeding their distance apart in length, 

 their width scarcely ^ of their length ; about 5 cell points in 2 lines of the margin 

 of ordinary sized specimens of all shapes, but 7 in the same space close to the base, 

 or in 3''0ung specimens 3 lines long. 



References and Synonyms. — Priorwtus folium (Hisinger), Lethsea Suecica., 

 pi. 34, fig. 8; D. ovatus (Barrande), Graptolites de Boheme, pi. 3, figs. 8 and 9; 

 Ph7jllograptus typus (Hall), Geol. Surv. Can., dec. 2, t. 15, figs. 1-12. 



I have little doubt, from careful comparative measurements of 

 Bohemian and Swedish specimens, that l^oth this form and the 

 D. ovatus of Barrande, fi-om the Bohemian basin, may ultunately 

 be proved to form only varieties of the Swedish D. folium of 

 Hisinger. The gigantic size of the Australian type is the first 

 distinction which strikes the eye (the length and width commonly 

 .3 or 4 times that of the European examples) ; but the most important 

 distinctive character seems to be the extraordinary width and thick- 

 ness of the midril) or axis. This, in the Bohemian and Swedish 



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