CAMBRIAN 239 



meshwork as in other Protopharetrce. Inner wall unusual, and formed of a coarse 

 regular mesh with large oval openings. Possibly 6 millimetres in diameter Avhen 

 complete. 



Probably fragment of a Protopharetra like P. rete (Taylor). The structure shown 

 reminds one of the septa in Photo 73, Plate XIII. The differentiation into two 

 zones, an outer paler portion and denser median portion, has been noticed in several 

 Protopharetra; and allied forms — especially in the "pillars" of P. duhiosa (op. cit., 

 p. 150 Memoir), though it is more regular than the latter species. 



Plate LXXVIII. Fig. 6. This body, though undoubtedly organic, is very in- 

 definite in structure. It resembles P. duhiosa — in itself a doubtful species — more 

 than any other of the Archceocyathince. It seems to consist of irregular enveloping 

 laminse from which structures of a lobe-like nature originate. Some apjiearance of 

 jmrallel rods also recalls the " pillai's" of P. duhiosa [op. cit., p. 150), with which it 

 may be provisionally allied. At the same time its ii'regularity is so pronounced that 

 it is not impossible that it is merely a form of rooting attachment. 



Plate LXXIX. Fig. 1. This organic material is too indefinite for identifica- 

 tion. It may be portion of a rooting structure, and the same remarks apply to this 

 section as to Slide 118. 



Plate LXXIX. Fig. 2. In this slide a very curious organism is shown in cross- 

 section. The appearance is that of an aunulus of about 2 millimetres diameter, built 

 up of contiguous oval cells, some fifty or sixty completing the circle. A fragment of 

 this annulus reminds one of a cross-section of Hcdysites, but the resemblance is 

 merely accidental. Within this outer circle are indications of inner circles of a 

 delicate nature, and there is some appearance of rays or spines connecting the circle. 



No sign of this extraordinary organism appeared in other slices, so that it is im- 

 possible to say if this circular section indicates a sphere, cylinder, or cone. It cannot, 

 I think, be classed with the Archceocyathiyice ; though Rhahdocyathus, a most aberrant 

 ally {op. cit., p. 169) of the class, might conceivably give a cross-section like this. 



Plate LXXIX. Fig. 3. Several organic fragments appear in this slide. The 

 photo figures some of them, notably one which resembles a cross-section of a trilobite, 

 but the material is too much altered for identification. 



There is also a minute hour-glass-shaped body of unknown affinities, certainly 

 unrelated to the Archceocyathince. 



Plate LXXIX. Fig. 4. An indeterminate fragment. 



Tuning-fork Spicule of Lelapia.* 



Plate LXXIX. Fig. 5. The occurrence of this very interesting spicule deserves 

 to be recorded, though there is little probability that it is derived from the Archceo- 

 cyathince. In the South Australian specimens numerous isolated spicules were 

 detected, and some are figured in my Memoir (Plate VI., photo 35). The shape of 



* Treatise on Zoology, part 2, 1900, p. 102, fig. 72a 



