ON FOSSIL SPONGES FEOM METIS. 



41 



This species is nearly as abnudaut as the precediug, and is often seen without the 

 anchoring rods while the latter are also often seen detached. 



In comparison with the previous species the root spicules arc not only quite different, 

 but the skeleton of the body differs in some important particulars. The cruciform spi- 

 cules have somewhat longer arms and form wider meshes, while they are very slender 

 and scarcely at all thickened at the nodes. The surface is also invested with very 

 numerous superficial or protective needles, giving a hispid appearance at the edges, 

 while the meshes of the central part are obscured by the superficial spicules flattened 

 down on them. The form and character of the osculum or oscula have not been observed. 



3. — Fkotospongia coronata, S.N. 

 (Figs. 8, 9, and 10. PL III, fig. 4.) 



Fig. 8. — Protospongia coro- 

 nata. Restored. 



Fig. 9. — Protospongia coronata. Primary, secondary 

 and protective spicules, x 5. 



Body ovate, small, 2 cm. long, spicules coarse and four-rayed, so connected as to give 

 the appearance by their obliquity of a diagonarl network of rhombic openings. This may 

 possibly be the effect of flattening. Numerous small cruciform flesh spicules. Eoot 

 spicules strong, short or broken off, 2 to 4. Osculum large, terminal, covered with a 

 conical hood made up of curved spicules converging to a point, and 1 cm. in height. 

 A few short superficial spicules visible at the sides. 



F^"*-^ 



Fig. 10. — Protospongia coronata. Showing 

 internal cavity. 



This is a small but interesting species, remarkable not only for its conical hood, but 

 also for the rhombic meshes and the development of the nodes of the larger cruciform 

 spicules, as well as for the stoutness of the latter, their rays being much thickened toward 

 the centres. 



Sec. rV, 1889. 6. 



