28 On the Spongia coriacea of Montagu. 



tica " by De Loriol ; so I returned to the subject [ih. vol. xii. 

 p. 26), when by having made and mounted microscopic 

 sections myself, I was enabled to give a more detailed de- 

 scription of the fact, and to announce that such spicules also 

 existed in the same position in my specimens of Verticillites 

 anastomans from Faringdon ; but on neither occasion had I 

 time to illustrate this interesting discovery, which is so 

 likely to pass unnoticed without representations, that I have 

 availed myself of the present opportunity to fill up a vacant 

 space with these, taken from my own preparations (PI. I. 

 figs. 6-10). 



EXPLANATION OF PLATE I. 



Fig. 1. Leucosolenia laciinosa, var. Hillieri, u. Tar. Natural size. 



Fi(j.2. The same, inagniiied 3 diameters, to show : — a, body, composed 

 throughout of massive dathrous or reticuh\ted structure. Body 

 not hollow, h, vent or osculum ; c, stem ; d, scopiform expansion 

 of stem into reticulated structure of body ; e, root-like attach- 

 ment ; /, tubular thread-like fibre j g, meshes of clathrate 

 structure. 



Fig. 3. The same. Summit more magnified, to show the continuity of 

 the vent with the reticulated tubular structure of the body. 

 a, vent ; b, tubulated thread or fibre ; c c, meshes or interstices 

 of the reticulated structure. 



Fig. 4. The same, Triradiate spicides of the body and centre of the 

 stem respectively, a, largest form ; h, smallest ; c, dotted line, 

 illustrative of the iuequiradiate forms. 



Fig. 5. Tlie same. Substraight linear and linear contort spicules of the 

 stem, a, substraight lijiear ; b b, linear contort ; c cc, nodes j 

 dj intermediate form. 



N.B. — All these spicules are drawn to the scale of l-24th to 

 1-GOOOth inch. 



Illustrations of the Pin-like Spicules {? jmrasitic) ^-c. on Verticillites. 



Fig. 6. Verticillites Itelvetica, De Loriol. Horizontal section of the wall 

 of a cylinder at the inflation, magnitied 4 diameters, to show 

 the structure of the wall and its hourglass-shaped openings or 

 canals, a, cavity of inflated chamber ; b, wall, apparently com- 

 posed of little oval and quadrangular elements, because, in some 

 instances, the section has passed through the hourglass-shaped 

 canals, and in otliers not. Diagrammatic. 



Fig. 7. The same. Vertical section of part of the wall of a cylinder at 

 the inflation, viewed from the inside ; magnified on the same 

 scale, to show the structure of the wall and its hourglass- 

 ehaped openings in this view, o, wall, noio seen to be continuous 

 and not formed of separate elements, as the foregoing figure 

 apparently represents ; b, inner opening of the hourglass-shaped 

 cauals, with a dot in the centre, to represent the narrow part. 

 Diagrammatic. 



Fij. 8. The same. Horizontal section of two of the so-called " oval 

 elements " Avith the hourglass-canal between them filled with 

 sand ; magnified on a scale of l-24th to l-1800th inch, a, out- 

 side of inflation ; b, inside ; cc, so-called " oval elements," com- 

 posed of homogeneous crystalline calcite, with minute fibrous 



