534 HYATT'S REVISION OF THE 



Spongelia velata Hyatt. 



This extraordinary sponge (PI. xvii, fig. 8) appears at first sight to have very good 

 claims indeed to the distinction of occupying a group by itself. The surface is com- 

 posed of a veil of finer texture than the interior, which, as in Spongelia cana, variety 

 cincta, limits the number and diminishes the size of the excurrent orifices. This veil, how- 

 ever, is much more distinct from the body of the skeletal fibres than in any other species in 

 which such a modification of the surface has been observed, and may possibly be quite gen- 

 eral and of specific value. This is doubtful, however, and at present it is best to look 

 upon it as the exaggerated development of a variation, probably due to the habitat of the 

 sponge. It is, however, in these specimens, a thin epidermal covering, while in all other 

 cases it is merely a denser aggregation of the secondary fibres as they approximate to the 

 surface. In Spongia Maurltiana, variety tectoria, a very similar thin covering S2ireads 

 over the whole surface, but even this is not distinctly separated from the internal fibres, 

 but seems leather a netwoi'k of minute fibres stretching across the open meshes of the 

 larger fibres, which also form a portion of the veil texture. In this species, however, the 

 internal fibres do not interrupt the smaller fibres, which form the entire substance of the 

 veil on the outer side. The fibres are coarse, the mesh very irregular in shape and size. 

 The arrangement of the primary fibres seems to be in thick sheets, or fan-shaj^ed expan- 

 sions, which radiate outwards. 



It will be seen that it is really similar to the structure of Spongelia chibia, variety exca- 

 vata, but with larger and more irregularly shaped canals and less solidity to the skeletal 

 partitions between them. No comparison can be made, however, between the inti- 

 mate structure of the skeleton itself, this species being in every way so much coarser fibred 

 and more irregular, the color also inclining to dark red or yellow. 



Loc, Zanzibar, in Coll. Peabody Academj', and in Soc. Coll. 



Spongelia dubia Hyatt. 



This species (PL xvii, fig. 9) resembles in general aspect the figure of Di/sidea fragilis 

 Johnst., but the description of the latter seems to show that Johnston really described a 

 true Dysidea, and not a meml)er of this genus at all. The specimens examined from Bis- 

 cayne Bay of the typical variety, are remarkable for the smooth aspect of the surface, due 

 to the closeness of the projecting points of the primary fibres, which hold up the epidermis 

 and prevent it from settling down between them into the usual pit-like depressions on some 

 parts of the dried sj^ecimens. On other parts of the surface the depressions are present, but 

 much smaller than in any other species. The primary and secondary fibres are quite reg- 

 ular in their arrangement, and there is but a slight development of the irregular net-work, 

 so characteristic of some other species. Habitat, shallow waters. Color when living black. 



Loc, Biscayne Bay, in Soc. Coll. 



Variety moUior. This variety, if it really does belong to this species, is described 

 from a type specimen named by Schmidt Caccosjjongia molUo7' f Schm. The textui'e is 

 fine, the primary fibres distinct, and tlie mesh of the tissue of secondary connecting fibres 

 similar to that of the typical variety, but considerably finer. The primai-y fibres do not 

 project perceptibly above the surrounding surface, which is quite smooth. The form is 



