NORTH AJMERICAN PORIFERiE. PART II. 549 



Variety nigra. This form (Pl.xv, fig. 21) is apparently intermediate between Hircinia 

 acuta and the solid varieties of Hircinia campana. The exterior has considerable resem- 

 blance to the varieties of the latter with a coarse surface, but the structure is more papery, 

 the spinous projections readily yielding to the touch even in the most carefully dried speci- 

 mens. These spinous projections are also shorter than in H. campana, and much smaller 

 than in H. acuta. The epidermis is more destructible than it is usually in H. campana, 

 and therefore very distinct from the coarse persistent eiiidermis of H. acuta. The skeleton, 

 however, has the same open structure and want of elasticity also observed in H. acuta, so 

 that, as stated by Dr. Palmer, the greatest care must be taken in drying in order to pre- 

 serve the form. The shape is the same as in H. acuta, and the arrangement of the excur- 

 rent apertures similar, but less sieve-like. The interior, also, is cavernous, as in that 

 sj^ecies and in H. Jilamenta. The filamentous tissue is present, but not so abundant as in 

 H. acuta or Jilamenta, and much more easily removed by maceration. Color in the living 

 sponge black, in the dried form black to dark gray. Habitat, reef. 



Loc, Biscayne Bay, in Soc. Coll., and Florida, in Mus. of Comp. Zoology. 



Variety longisphia. 



Polytherses longisjiina Duch. et Mich., Op. cit, p. 71. 



This form, of which I have seen but one specimen, is readily distinguished by the struc- 

 ture of the bundles of primary fibres. These are cylindrical bundles constructed, as in 

 Stelospongos, of long primary fibres united by a secondary and rather closely set system of 

 transverse fibres. In fixct, so strong is the resemblance that it was at first classified with 

 that genus. The intimate study of the fibres themselves, however, show that they belong 

 to the Hircinian type, especially the broad membranous junction of the secondary with the 

 primary fibres and their color. The intermediate filamentous tissue is also present, and 

 helps to identify the species as a Hircinian form. 



Loc, Havana, in Coll. Mus. Com]). Zoology. 



Hircinia cartilaginea Hyatt. 



Spongia cartilaginea Esper, Pflanzenthiere, vol. 3, pi. 64. 



This form may be at once distinguished by the peculiar structure of the skeleton. The 

 primary fibres broaden out before branching into exceedingly flat, flabellate fibres from one 

 to three mm. broad. The branches then appear separated by a vesicular tissue of second- 

 ary fibres, the meshes of which are at first, when in the crotches of the branches, very 

 round and minute, but gradually enlarge, and finally stretch fro"m branch to branch of the 

 fibre in the usual form. This of course is a characteristic of great variability, and often 

 in the same specimen the observer finds quite an open tissue in some parts, and in others 

 an almost closed network, and in some cases a continuous shelf stretched vertically be- 

 tween the vertical branches. The five specimens examined were completely macerated, 

 and this may account for the absence of filamentous tissue. 



Loc, Key West, in Soc. Coll., and Florida, Havana, in Coll. Mus. Comp. Zoology. 



Variety horrida. One of the specimens examined is a bi-fistural form (PI. xvii, fig. 29) 

 with a skeleton partly of a curious pinkish hue, due to the bright colored foreign matter, 

 fragments of Corallines, taken into the fibres from the epidermis. The mesh in the interior 

 is exceedingly regular, consisting of broad, upright primary fibres, bound together by sec- 

 ondary fibres of a sunilar broad, flattened form, these again united by a vertical set of 



MEMOIRS BOST. SOC. NAT. HIST. VOL. 11. 138 



