NORTH AMERICAN PORIFERiE. PART 11. 539 



the channels of the surfoce in a sponge are essentially the product of the sub-epidermal 

 horizontal canal system, and serve as lines of communication with the neighboring vertical 

 canals. 



Loc, Mauritius, in Coll. Mus. Comp. Zool. 



Spongelia anceps Hyatt. 



This form, of which I have only seen one specimen, is remarkably distinct from any 

 species here described. It closely resembles Sj^oitgelia Kirkii in appearance, but differs in 

 the aspect of the fibre, which is not so coarse, and the generally finer look of the skeleton. 

 There is also no net-like connecting tissue as in Kirkii, and I separate them on this 

 account. The cells, also, are very regularly formed, the primary fibres regular and single, 

 and the secondary laid up between them in the most regular manner. It is the very type 

 of a Spongelian. 



Locality unknown ; in Coll. Acad. Nat. Sciences, Philadelphia. 



Spongelia ligneana Hyatt. 



This species is allied to Spongelia duhia in general appearance, owing to the smooth 

 asjDect of the surface. It has, also, an exceedingly dense skeleton and a very small mesh 

 between the fibres. The primary fibres project slightly above the surface in single points, 

 and the whole is exceedingly hard and harsh to the touch. The fibres are very coarse, 

 and the prhnar^^ fibres very opaque, and also loaded with debris. A singular appearance is 

 given to all the fibres by the abundant development of the concentric layers of keratode 

 which surround the primitive cores. These last are quite transparent, so that under the 

 microscope the effect is that of a hollow fibre, until the double outline or end view shows 

 their solid character. The fibrous structure of the darker external part is also particularly 

 noticeal)le. 



Loc, Zorritos, Peru, in Yale Coll. 



Spongelia Kirkii Hyatt. 



Dysidea Kirkii? Bow., British Spong., Vol. i, p. 212. 



The single specimen (PI. xvii, fig. 19) examined possesses the coarsest skeleton of any 

 species in this genus. The primary fibres are very thick, inelastic, and loaded with 

 foreign matter. They project considerably beyond the surface, and the quantity of foreign 

 matter in them gives them a peculiar whitish granular aspect. The connecting secondary 

 fibres are a dark horn color and excessively large, especially in the older j)arts, such as the 

 pedicle. They are also very widely separated, and more inelastic than the primary fibres. 

 The result of this structm-e is an exceedingly open skeleton, through which you can 

 see with ease, but which cannot be compressed in the slightest degree without breaking 

 the fibres. The form is thick, erect, and irregularly flabellate, but the excurrent orifices 

 are irregularly distributed on the top and sides, and, in fact, are hardly distinguishable at 

 all upon the skeleton. The pedicle is thicker than the upper parts, and very much harder. 

 In the lower parts of this pedicle the connecting tissue has become very dense, j^resenting 

 quite a cellular aspect for consideraljlc spaces, owing to the number of extra fibres secreted. 



