A UEVISION OF THE GENUS STEGANOPORELIiA. 253 



4. S. simplex, n. sp. Figs. 7, 21. 



Zoa3cia of large size. Cryptocyst joining the distal wall 

 close to its origin fi'oui tlie basal wall; angnlated audtliickened 

 laterally at the coniniencement of its descending portion. 

 Roof of tube sbort, tliick-walled, and tubercular ; the opening 

 vertical and separated from the distal wall. Median process 

 not distinct from the tube, b zooecia not found. A opercula 

 with two strong recurrent teeth on the main sclerite. 



Darros Is, (Amirante Is.). (B. M., 82.10.18, 125.) 



This species is founded on a single encrusting fragment 

 removed from a dry preparation v/hich otherwise consisted 

 of S. sulcata. It differs from that species in its larger size, 

 in the fact that the cryptocyst joins the distal wall,^ and in 

 the remarkably simple character of the tube and median pro- 

 cess, the latter being indeed hardly distinguishable from the 

 tube. The edge is but slightly raised. The post-oral shelf is 

 boldly tubercular, deep, and descending steeply to the crypto- 

 cyst, which is thus a good deal depressed; the shelf is less 

 developed proximally. The oral shelf is present, but is narrow 

 and hardly tubercular. The condyles (for the hinge of the 

 operculum) are blunt and massive. The oral arch is strong 

 and moderately raised. The cryptocyst is thick, very tuber- 

 cular^ and with small pores ; its descent is oblique, though 

 with a steep slope. The tube is not much more than a mere 

 perforation in this oblique partition, its upper border being, 

 however, developed into a short but massive and tubercular 

 portion, which thus forms a spout-like prolongation of the 

 perforation in the cryptocyst (fig. 7). The tliickening of the 

 cryptocyst at the descent of the lateral recesses may slightly 

 extend on to the base and sides of this tube, thus giving rise 

 to a hardly appreciable concavity, which is all that can be 

 compared with the cavity of the median process. The epi- 



^ A. larger quantity of material niiglit perhaps show that the union was 

 sometimes with the basal wall in the neighbourhood of the distal wall. 



