XORTH AMERICAN PORIFER^. PART II. 521 



apt to have the interior pierced by galleries, which often honeycomb a sponge which 

 seems superficially to be very solid. The top is covered by a remarkably thick membrane, 

 which in many specimens is not piei'ced by excurrent apertures on or near the edges. This 

 gives a partially smooth zone or border, which, when it is present, contrasts in a remark- 

 able manner with the apertion of the central part. The whole of the top, with the 

 exception of the border, is perforated by excurrent apertures of small size, so numerous 

 that they are often separated only by the dividing wall common to the contiguous tubes. 

 The sides may either be furrowed or have a pitted appearance, according to the presence 

 or absence of tufts of fibres, but in no case are the furrows divided by such regular 

 ridges as in variety typica. 



Loc, Florida, in Soc. Coll., and Kingsmill's Islands, in Coll. Mus. Comp. Zool. 



Variety divisa. The form is divided in this variety into several large flattened lobes, 

 which are apt to have a rougher surfiice on the sides and be more cavernous than the col- 

 onies of the typical variety. The length of the tufts gives a furrowed aspect to the upper 

 side of the skeleton in some specimens. According to Dr. Palmer's observations, the color 

 of the animal while living is black, and it is found upon hard irregular bottom or corals in 

 about two feet of water at low tide. 



Loc, Key West, Biscayne Bay, in Soc. Coll., and Stono Inlet, S. C, in Coll. Mus. Comp. 

 Zoology. 



Variety 3fexicana. This variety (PI. xvi, fig. 28) approximates closely in form to variety 

 divisa, but the loose open texture of the inner side, due to the nimiber and close approxi- 

 mation of the excurrent orifices is replaced by a closer web, in which only few apertures 

 are visible. It is in fact more like sub-species corlosia in this respect ; the texture and 

 surface, however, are like those of this sub-species. 



Loc, Vera Cruz, in Mus. Comp. Zoology. 



Variety ccdiciformis. The external surface (PI. xv, fig. 9) of the dried specimen, and 

 even the cavernous character of the interior, with the large openings of the galleries per- 

 forating the sides, are the same as in the preceding varieties. The differences are due to 

 the form, which is regularly vase-shaped (PI. xvi, fig. 30), and to the surface of the infun- 

 dibuliform side. This last is not only perforated by numerous contiguous excurrent ori- 

 fices, but also by many of the galleries from the cavernous interior. This gives to a 

 portion of the upper surface a very much more rugged or broken up aspect than is found 

 in the preceding varieties. 



There are three skeletons of this form, two from Nassau, and one, locality unknown. 

 The two from Nassau exhibit a light yellowish brown skeleton, nearly as harsh to the touch 

 as that of Spongia agaricina, sub-species dura. One of the Nassau specimens has the 

 inside of the cup of much denser structure than in the others, and the rim perforated. This 

 transposition of the area occupied by the excurrent orifices is, however, not the only sole- 

 cism. The surface of the sides is divided by deep channels into primary and secondary 

 tufts, precisely similar to those of "the following variety. 



Variety ohscura. This (PI. xvi, fig. 29) is found at Nassau, and also occurs at Key West ; 

 at least the color of some skeletons indicate that locality, the fibres being harsh and deep 

 brown to reddish brown near the centre. The surface is rounded, and pierced by numer- 

 ous orifices surrounded by ridges and tufts of considerable length. The aspect of these is 

 such that I formerly referred this form to variety hirsuta of sub-species gossypina. 

 This variety also occurs at the Bermudas, according to Mr. Goode's collection. A coUec- 



MEMOIRS BOST. SOO. NAT. HIST. VOL. II. 



