NORTH AMERICAN PORIFERiE. PART II. 547 



campana, and are decidedly larger. Those that have only one or two orifices are really 

 fistular, but lead into solid forms with projecting oriiices. They may be single, or 

 multijile to such an extent as to form large masses, and they may also be truncated, 

 or furnished with projecting excurrent tubes. The branches springing from the typi- 

 cal vase-form are flattened, and they precisely resemble the flabellate forms in struc- 

 ture and aspect. These may be either as described by Duch. et Mich, in their " Spong. 

 de la Mer Caraibe " bi'anched above like P. armata, or with an entire border, as in P. 

 tristis, ignohilis and Uncjuiformis, or with a semicircular form and a line of orifices above, 

 as in P. marghialis. 



The modifications of form, in fact, seem almost endless, including also those like P. col- 

 umnaris (PI. xv, fig. 17) and P. cylindrica Duch. et Mich., which are composed of stout 

 branches. There are also numerous variations of all these, and some colonies which may be 

 considered amorphous (PL xv, fig. 18), in so far as they appear to be composed of branches 

 irregularly soldered together, and having several points of attachment. The extent and 

 accidental character of the variation make them exceedingly difficult to classify, and I have 

 not been able to distinguish some of them in a satisfiictory manner. These variations ai-e 

 not confined to the form, but extend also to the skeletal tissue, which may be either exces- 

 sively coarse and open, with a rough surface and large spines, or quite fine and close in 

 structure, with smoother surface and vei'y slight spinous projections. The sunken inter- 

 spaces between the spinous projections may be from 2 mm. to 10 mm. in diameter. The 

 general size is about 4 or 5 mm. According to Dr. Palmer, this species is not difficult to 

 dry, and retains its form on account of the density and comparative elasticity of the skel- 

 eton. The interior in alcoholic specimens is usually very porous and open, owing to the 

 numerous canals and slight development of the mesoderm, but in some specimens quite a 

 fleshy aspect is assumed, though the mesoderm is never very solid. Color when living is 

 black, when dry reddish brown, or white. 



Loc, Nassau, Key West, Biscayne Bay, in Soc. Col. ; Havana, in Mus. Comp. Zool. Coll. 

 Habitat, reef in 4-10 ft. of water for the normal variety. Whether the other varieties 

 also occur in the same depth of water, was not stated by Dr. Palmer. 



Besides the above, there exists in the Coll. Acad. Nat. Sciences of Philadelphia a remark- 

 able variety. There are two specimens, the tallest about three inches, of slender, irregular, 

 branch-like forms, but consisting each of a perfectly fistular tube witli very thick walls. 

 This appears to complete the remarkable cycle of varietal forms, which are represented in 

 this species, and which might very reasonably be described as many distinct species, on 

 account of the extraordinary characteristics found in the skeleton, which often differs in 

 texture as much as the varieties differ in form. I have not, however, succeeded in finding 

 any constancy in the skeleton of any special form, or series of forms, the texture appearing 

 to be independent of the form. A thick lump-like form of this or a closely allied species, 

 has also been collected at La Paz, Lower California, and presented to the Society by 

 Mr. W. G. W. Harford, and two specimens have been received from the Peabody Academy, 

 Salem, from Zanzibar, which do not seem to differ from the ordinary type of the skeleton, 

 except in the quantity of contained sediment, this being less than is usual in Florida spec- 

 imens. Mr. Goode also sends nearly all the described varieties from Bermuda, so that it 

 would appear to be cosmopolitan in distribution. 



