524 HYATT'S REVISION OF THE 



at the bottom than near the top, which is rounded ; in the second the same form is the 

 typical one, but there are also some very flat table-like specimens ; in the third the same 

 forms occur with others, which manifest a tendency to throw out branches. In one or two 

 specimens also from Nassau, which may be referred to this variety, the surface is precisely 

 similar to that of discus or tuhulifera in general appearance, but a close examination shows 

 the numerous and peculiar tufts of primary fibres which distinguish this species. 



Sub-species corlosia. 



Spongia corlosia Duch. et. Mich., Op. cit., p. 31. 



This, which is popularly known as the " Yellow Sponge " of commerce, was at first 

 confounded by me with Spongia dura, the " Hard Head" (PI. xvi, fig. 24), but an exam- 

 ination of a full series of forms showed that very considerable differences exist in the 

 texture, though superficially there is little or no distinction in the aspect of the surface. 

 Dealers can identify these varieties instantly by the color, which is usually lighter than 

 that of the "Hard Head," and by the touch, the "Yellow Sponge" yielding much 

 more readily and feeling less harshly imder the fingers. These characters, however, only 

 apply to the normal head-like forms and some of the varieties ; many forms cannot be 

 placed in either one or the other of the two groups with any certainty. 



Loc, Nassau, in Soc. Coll. 



Variety gossypiniforinis. This is the most remarkable variety (PI. xvi, fig. 26), and 

 it approximates to corlosia, not only in external aspect, but in form and color and gen- 

 eral texture. The form is similar to the fistular varieties, with one or two very large 

 orifices above, and the color of skeleton is much lighter than that of the other varieties. 

 It is also permeated by larger canals than in other varieties, and thus the general texture 

 approximates more closely to the softer and more porous character of this sub-species. 



Loc, Nassau, in Soc. Coll. 



Variety fusea. The young, and some few older specimens which I have referred to this 

 form from Key West, have the surface of the skeleton on the sides more like those of sub- 

 species dura (PI. XV, fig. 11; PI. xvi, fig. 31). The skeleton of many of the young also 

 presents charactei-istics almost identical with those attributed by Duchassaing and Michel- 

 otti to sub-species cerehrlformis. The top surfaces are, however, not so similar ; they being 

 almost devoid of the broken aspect so characteristic of sub-siDecies cerebriformis. The shape 

 is pretty generally like that of an inverted, truncated cone ; the top flaring more or less in 

 all specimens, and either slightly gibbous, or flat. The excurrent orifices which occupy this 

 area are but slightly protuberant, and there is no such mai'ked zone between them and 

 the sides as in sub-species cerehrlformis, variety conqjlanata, nor are the apertures, even 

 when small, so numerous, or arranged according to any describable plan. The color in a living 

 state is black, and the largest specimen observed by Dr. Palmer was about eight inches in 

 height. This collector also reports it as found growing almost exclusively U23on coral and 

 other sponges. One young specimen has a projecting branch in every respect identical 

 with the following. 



Variety elongaia. This (PL xv, fig. 10) has an elongated form, sometimes slightly 

 branched, the branches thick and club-shaped, but never fistulose. The larger number of 

 the specimens are young, and were collected from Biscayne Bay, and named by Dr. Palmer 

 " Small Hard-Heads." This commercial designation is, however, of doubtful correctness. 



