522 HYATT'S REVISION OF THE 



tion of waste sent home by Mr. Saltonstall contained a number of this variety which con- 

 clusively settled the question of the affinity of the species ; some of these specimens are 

 forms of gossypina, and some of cerehriformis. 



Spongia agaricina Pall. 

 Spongia ayaricina Pall. (Esper Pflanzth., 2, pi. 14). 



Sub-species Zimocca. 



Spongia Zimocca Schm., Op. cit., p. 23. 



This species varies like Spongia officinalis, but the cup-shaped varieties are much flatter 

 and broader, and from these there are all imaginable variations. The interior may rise into 

 a prominent bulging dome-like centre, the excurrent orifices still presenting, however, the 

 pitted aspect, and the surface the hirsute structure and dark color so characteristic of the 

 species (PL xvi, fig. 22). These solid forms may be more or less lobed, and continue to 

 grow until a very irregular lobate form is produced, which is almost a true branching stock. 

 The qualities follow the same law of variation, the irregular forms being generally the 

 coarsest, and these approximate in a remarkable way in quality and the aspect of the ori- 

 fices and surfiice to the finer qualities of the American varieties.^ The typical form, as 

 figured by Esper, has all the peculiarities, including even the dark color of the skeleton, 

 which is characteristic of this species ; and since Dr. Ehler has referred it to this genus I 

 do not think there can be any reasonable doubt as to the proper limitation of Esper's name. 



Sub-species dura. 



The fibres of all the American forms are considerably coarser than those of gossyjnna in 

 all of the normal forms, but of course in some varieties this distinction does not hold. 



1. The primary and secondary, or connecting fibres are equal in size. The former are 

 continuous below, and single. The latter have a precisely similar aspect, and run parallel 

 with the primaries for considerable distances before bending laterally to anastomose with 

 others and form the mesh of the connective tissue. They are, however, never loaded with 

 debris, but the mesh is, in consequence of this peculiar structure, long and narrow, and 

 mostly arranged vertically. 



2. Primary and secondary fibres project in tufts above the surface, and are connected 

 by a third system of short horizontal fibres, as in the Stelospongas group. 



Variety typica. This sub-species, the form known in commerce as Hard-Head or Honey- 

 comb reef sponge (PI. xvi, figs. 24-25, and PI. xv, fig. 6) is very closely allied to sub- 

 species gossypina in some respects. The color is darker and the texture denser than in the 

 latter, and yields only to considerable pressure between the fingers. The surface presents 

 large tufts of fibres, and between them canals, resembling in this respect the surface of vari- 

 ety meandriforynis of sub-species gossyjnna, but difiers in the minor tufts of fibres. These 

 are more minute than in gossypina, and present a more hirsute or bristly aspect. The typi- 

 cal commercial forms are not to be found in the shallower waters, they being mostly gath- 

 ered beyond the depth of sixteen feet. The color, as reported by Dr. Palmer, is black when 

 living, with a brownish tinge. He also says that they are usually more isolated than 

 gossypina, and not closely associated with other sponges, though growing upon the reefs. 

 The largest observed was probably about six inches high by sixteen to twenty inches 



1 The specimen figured is one of the exceptions to this rule, since it has a slielcton of remarkably- fine texture. 



