NORTH AMERICAN PORIFERJE. PART II. 527 



Another specimen, in all probability belonging to this form, in the Yale Collection, has 

 a precisely similar mesh but no veil. The mesh is small and remarkably regular, and there 

 are no well marked primary fibres. No locality. 



Spongia lapidescens Duch. et Mich. 



Spongia lapidescens Duch. et Mich., Verhand. Maatsch. Wetensch. Haarlem, 1864, 21-2, 

 p. 34. Spong. de la Mer Caraibe. 



This species is very closely allied to the typical variety of Sjjongia vermiculata in the 

 aspect of the surface, and general texture and hardness of the skeleton ; this is especially 

 the case with the fistulose varieties. The whole aspect of the surfiice, the tufts and their 

 structure, show considerable affinity with sub-species cerehrtformis, but on the other hand, 

 the extreme density of the skeleton and stiffiiess of the fibres seems to indicate that a 

 separation is necessary. The permeability of the outer membrane to debris of all kinds 

 also favors this conclusion. 



Variety typlca. The entire surface (PL xvii, fig. 3) is covered by tufts of fibres, which 

 are parallel and closely appressed, but rarely connected by lines of secondary fibre. These 

 bundles in some specimens may be very thick and brush-like. They approximate to the 

 aspect of the surface in sub-species Maur'itkina, which has similar large bundles of fibres, but 

 of a more complicated or net-like structure similar to the body of the skeleton. The pecu- 

 liar structure of these tufts is shown by the chenille-like aspect of the tops, due to the 

 projecting free ends of the primary fibres. 



Loc, Havana, in Coll. Mus. Comp. Zoology; Florida, in Soc. Coll., and Hayti, in Coll. 

 Peabody Academy, Salem. 



Some specimens of this variety have tufts of all shapes and sizes, and one is nearly 

 smooth on one part of the surface, showing very prominently the small round oscules pep- 

 pered in between the tufts. This leads into the next variety. 



Loc, Havana, in Coll. Mus. Comj). Zoology, and Soc. Coll. 



Variety tetheaformis . The name alludes to the faint resemblance to a dried Tethea, 

 due to the similar aspect of the tufts of j^arallel fibres and the bundles of threads in a 

 dried specimen of that genus. These are very long and very closely set, often joined 

 into crests, parallel and quite sharp above, differing in this respect from the blunt aspect of 

 the bundles on the cracked surface of a dried specimen of the siliceous genus Tethea. 



Loc, Havana, in Society's Coll., and in Mus. Comp. Zoology. 



Variety intermedia. The texture is generally somewhat looser, the oscules larger and 

 the tufts longer and more irregular, varying in the same specimen from forms comparable 

 with those of the typical variety to those in which they assume a fan-like outline, and are 

 composed of only a thin laj'er of fibres. 



Variety turrita. In this variety (PI. xv, fig. 12) the parallelism of the fibres of the 

 superficial bundles is less noticeable than in the preceding variety, these parts being, as in 

 the generality of the Spongite, composed of fibres more or less interwoven. The fiin-shaped 

 or flattened tufts, however, usually have the fibres parallel, and the surface is similar to 

 that of the other varieties, with the following exception. Large oscules occur irregularly 

 scattered over the mass, which are elevated upon fistular projections of the skeleton. 

 Near the apertures the walls of these are remarkably thin, and built up of the same tissue 

 as the body of the sponge, but with a more regularly elongated mesh and more decided 



