NORTH AMERICAN PORIFERiE. PART II. 515 



that thoy can be joined ; this, however, is not the case, and the resemlilance disappears 

 upon close comparison. 



Loc, New South Wales, near Sydney, in Acad. Nat. Sciences, Philadelphia and in Soc. 

 Coll. 



Variety Auklinensis. This remai'kable variety spreads out into flat masses with project- 

 ing orifices, more or less fistulose, and branches. The whole surface is exceedingly hairy, 

 owing to the number and length of the bundles of projecting primary fibres. These are? 

 however, similar to the more scattered ones of variety Nicholsoni, and the surface other- 

 wise resembles that species. 



Variety Jicjnenformis. This variety is so named because the skeleton is consideral)ly 

 denser than in the two preceding varieties, the tufts less spinous and smaller, and all the 

 apertures smaller and more numerous. The fibres of the skeleton are also finer and more 

 densely woven together. 



Loc, Florida ? in Coll. Acad. Nat. Sciences of Philadelphia. 



Spongia lignea Hyatt. 



This species has the densest skeleton with the closest texture of any known sponge. 

 The fibres are quite fine, and the whole so hard that it cannot be compressed by the fin- 

 gers. The largest specimen I have seen exists in the collection of the Academy of Natiu'al 

 Sciences, Philadelphia. This is very much cut up in the interior by large channels, but 

 feels as if made of cork, or wood. Unfortunately, it is much beach worn, so that the orig- 

 inal surflice could not be studied. 



Loc, New South Wales, near Sydne3^ in Coll. Acad. Nat. Sciences of Philadelphia. 



The following varieties are closely allied to the preceding, and are probably the same, 

 but I have not the material to determine this question with certainty. 



Variety levis. One specimen from the Collection of Yale College, United States Explor- 

 ing Expedition, locality Pacific, exhibits a surface almost devoid of the projecting tufts, 

 owing in some measure j)robably to attrition on the beach. Where the surface has been 

 left entire in the hollows, the tufts are present, but not abundantly developed. The tex- 

 ture is excessively dense, and the surface reminds one strongly of that of sub-species tuhu- 

 lifera. This is owing to the innnense number and small size of the incurrent, and the 

 paucity of the excurrent apertures. 



Variety arborescens. There is one of the branching specimens exhibiting many of the 

 superficial and textural characteristics of this species, which belongs to the Collection of 

 Yale College, locality Pearl Island, Panama Bay. It seems closely allied to variety "levis " 

 in every resjiect except the branching form. 



Variety crassa. A specimen from Bermuda, in the Peabody Academy Collection, has 

 been referred also with some doubt to this species. It is very similar in most respects, but 

 the fibres are quite dark colored, and the secondary tufts stiff and rather short ; otherwise 

 the surface and general aspect agree with those of variety levis. 



A si3ecimen from Mauritius, in the Collection of the Museum of Comparative Zoology, 

 may possibly belong to this species. The texture is, however, quite similar to that of 

 sub-species Cookii, "var. vermiciclatiformis," while the surface is perhaps more like that of 

 the typical variety of this species. There are here and there large oscules, four or five 

 millimetres in diameter, with numerous smaller ones irregularly scattered between them. 

 The mesh is rounded, or cellular in aspect, and quite spongelia-like on the surface. The 



