FROM A DREDGING IN THE WEDDELL SEA. 
711 
organisms. The most obvious way in which the conditions could be adverse is by 
a climatic change, since other characters seem similar. It will be interesting to 
see whether subsequent discoveries confirm an apparent climatic differentiation during 
Cambrian times. 
In conclusion, I desire to record my thanks to Dr W. S. Bruce, leader of the Scotia 
Antarctic Expedition, for giving me the opportunity of examining and describing the 
Weddell Sea specimens, and for his forbearing in the long delay in publication ; 
to Professor W. W. Watts, F.R.S., who has acted as supervisor, for the University 
of London, and read over the manuscript ; and to Professor J. H. Ashworth, F.R.S., 
who, in my absence, read the paper to the Society. I am also indebted for 
assistance in preparing the sections of the material to Mr C. H. Benson ; to 
Mr J. Matheson, who has constructed the map showing the geographical points of 
Antarctica referred to in the text ; and to the Carnegie Trust for the Universities 
of Scotland for a generous grant to defray the cost of publication. 
EXPLANATION OF PLATES. 
(All figures are prints from untouched negatives.) 
Plate I. 
Fig. 1. Coscinocyathus endutus. Longitudinal section through inner wall, a, inner wall present ; 
b, inner wall replaced by crystalline calcite, porous structure indicated by darker matrix ; c, pores on outer 
wall. (Slide S. 97, x 7'5). 
Fig. 2. G. endutus. External surface of weathered specimen. Outer wall practically all removed by 
weathering. Porous structure still indicated near the base and on the sides. Septa and tabula? also shown 
as a series of cavities arranged in lines, a, septum, the holes really represent the solid part of the original 
septum, which is here dissolved away, while the solid part between the holes is the matrix filling in an 
original pore ; b, tabulae. (Slide S. 156, x 5.) 
Fig. 3. Epiphyton fasciculatum and E. grande. The relative sizes of the tubules are quite easily seen, 
a, E. fasciculatum ; b, E. grande. (Slide S. 44, x 9.) 
Fig. 4. E. fasciculatum. Slightly enlarged view of the thallus to show the tufted character, a, portion 
more highly magnified in fig. 4a. (Slide S. 69, x 25.) 
Fig. 4a. E. fasciculatum. Portion of a (fig. 4) more highly magnified to illustrate the equal bifurcations 
of the thallus and the swollen terminal portions, a, points of bifurcation. (Slide S. 69, x 90.) 
Fig. 5. E. grande. General view of a large tuft cut obliquely. Bifurcating character very apparent in 
places. (Slide S. 11, x 25.) 
Fig. 6. Sponge spicule ; probably heteractinellid. (Slide S. 103, x 20.) 
Fig. 7. Sponge spicule ; tetractinellid type, showing all four rays. (Slide S. 33c, x 20.) 
Fig. 8. Sponge spicule ; large form, probably heteractinellid. (Slide S. 113, x 20.) 
Fig. 9. Spicule similar in type to that of fig. 8. (Slide S. 81, x 20.) 
Fig. 10. Sponge spicule ; hexactinellid form. (Slide S. 23, x 20.) 
Fig. 11. Sponge spicule tetractinellid. Three rays beautifully displayed ; the fourth is vertical but is 
indicated by the knob at a. (Slide S. 76, x 20.) 
Fig. 12. Sponge spicule. Hexactinellid type with one ray bifurcated. Similar to Lelapia-Yike spicule 
of Taylor, a, spicule out through median plane ; b, a second example showing bifurcated ray only, as section 
is oblique to median plane. (Slide S. 102, x 90.) 
Fig. 13. Another spicule similar to that of fig. 12, but cut rather obliquely. (Slide S. 78, x 90.) 
