90 
McLean. — On the Fossil Genus Sporocarpon. 
at the region of the intercalary swelling, it will be seen that their walls are somewhat thickened, 
forming the framework referred to under Fig. i. Tams phot. Lent by Mrs. Scott, x ioo. 
Fig. 4. S. elegans. A truly tangential section through the colonnade with the units cut at 
different levels; upper swellings on the periphery of the section, lower (foot) swellings in the centre 
and ‘ waists ’ intermediately. The photograph shows the tangential connexions running between the 
units, with here and there a double contour, as if they were tubular. (Williamson Collection.) 
x 450. 
Fig. 5. S', compactum . Restoration of a single unit (cell) of the envelope, at the beginning of 
its elongation into the mature spine form. The tuberculae shown near the apex are really minute 
openings with pores at the tip of each of their very fine ramifications, x 2,000 approx. 
Fig. 6. S. compactum. Part of the envelope, showing two cells at A in process of elongation. 
(Author’s Collection.) x 450. 
Fig. 7. S. asteroides. Median section of a specimen with unusually long lobes. Interior capsule 
faintly shown. (U. C., London, Collection.) x 20. 
Fig. 8. S. asteroides. Young specimen in median section, showing part of the outer surface of 
a young lobe at a, with convex outer ‘ cell-walls’. (U. C., London, Collection.) x 80. 
Fig. 9. S’, asteroides. Two specimens, one containing a capsule with sporoids, the other 
apparently dehiscing and extruding a mass of spores (?) united by filaments. A unique specimen. 
Drawing by Mrs. Scott from a specimen in the Scott Collection, x 100. 
Fig. 10. S’, tubulatum. A young specimen in median section, showing the elongate cells of the 
envelope in their young form before their growth into spines. It will be seen that in this state their 
apices are obtuse. Compare with Fig. 11. (Author’s Collection.) x 80. 
Fig. 11. S’, tubulatum. Restoration of two spines in their mature state, showing their resem- 
blance to those of S’, elegans. The whole organism is, however, in this species spheroidal, x 1,000 
approx. 
PLATE IX. 
Fig. 12. S’, pachyderma. Section through a conjoined group of individuals with a common 
tubular investment. One, which is cut medianly, shows a peculiar colonnade of radial cells, remark- 
ably like that of S’, compactum , inside the normal tubular envelope. A unique specimen. (U. C., 
London, Collection.) x 75. See also Fig. 19. 
Fig. 13. S. pachyderma. Part of the tubular investment shown in tangential section. The 
branching of the large thin-walled tubes composing the investment may be seen near the centre. 
(Author’s Collection.) x 450. 
Fig. 14. S’, pachyderma. Spore or juvenile individual with very slight investment, found in 
close association with a large group of the same species. (Author’s Collection.) x 600. j 
Fig. 15. S’, pachyderma. Median section with double-walled capsule. The envelope shows 
apparent orifices externally at A and a spine base at B. (Author’s Collection.) x 450. 
Fig. 16. S’, cellulosum. Radial section with large ‘ sorus’ of spine bases. A small portion of 
the envelope is seen cut tangentially (A) , showing the polygonal outline of the envelope units. 
Fig. 17. S’. OidosporaC Two individuals, apparently conjoined. The structure of the envelope 
is very like that of S. compactum. (U.C., London, Collection.) x 700 approx. 
PLATE X. 
Fig. [8. S’, compactum. Median section of a very well preserved specimen with an unshrunken 
capsule filled with sporoids and granular matter which appears to be residual plasma. U. C., 
London, Collection.) x 700 approx. 
Fig. 19. S. pachyderma. Portion of the envelope of the specimen shown in Fig. 12. It will 
be seen that the radial cells are prolonged at their distal ends into the tubes which form the 
envelope, the prolongation being in each case flexed in the same (clockwise) direction, x 200 
approx. 
Fig. 20. Traquairia ramex. The type specimen of this species, which is here reproduced for 
comparison with the present genus. (U. C., London, Collection.) x 200 approx. 
