536 " HYATT'S REVISION OF THE 



the differences lie in the presence of continuous lines of primary fibres and the lesser 

 density of the whole skeleton. 



Loc, Mauritius, in Mus. Comp. Zoology, and in Soc. Coll. 



Variety rigida Hyatt. This, after much hesitation, seems to be appropriately classified 

 only when considered a distinct variety. The surface of the skeleton is covered by a thick 

 growth of primary fibres. The genei'al texture is finer than in SjJonr/elia dubia, which it 

 resembles closely, and the fibres smaller. It also still more closely resembles the t3'pical 

 variety of Sjnnosa, but even here the texture is not exactly similar. The primary fibres 

 are perfectly regular, and join the secondary fibres at right angles, and the projecting parts 

 of the primai-y are never surrounded by any deflected secondary fibres, as in variety spinosa. 



Loc, Beach at Ft. Pierce, Indian River, Fla., in Soc. Coll. 



Variety Codmani. This variety was gathered by Mr. Codman at the Island of Tenerifie, 

 and differs from the preceding only in the lightness of the skeleton, the smaller size of the 

 fibres, and the irregularity of the form. The surface is also a trifle less spinous. 



Spongelia Farlovii Hyatt.' 



Variety densa Hyatt. One specimen (PI. xvii, fig. 14) has a flabellate form from 10 to 

 15 mm. in thickness, and about 230 mm. in greatest breadth. The excurrent orifices are 

 situated along the outer border in a single row. Each orifice in the specimen examined 

 corresponded to a fistular swelling which rose like a ridge on the side. These ridges run 

 together below, so that many of the excurrent canals are thus traceable throughout their 

 larger ramifications. The structure is very dense, the surface smooth, the fibres small, and 

 the mesh of the tissue exceedingly fine. 



Loc, Phiflip's Island, Australia, in Soc. Coll. 



Y ariety jJfdmatiformis. This variety has an aspect not imVike that of Spongelia j^cd- 

 mata, owing to the thinness of the colony which jierraits the light to pass through quite 

 freely. The primary fibres are, however, closely approximated, and besides the ordinary 

 secondary fibres the peculiar open network of connecting tissue which distinguishes this 

 species from Spongelia rectilinea is also present. This consists of a very fine net-like con- 

 junction of threads finer than the secondary fibres, which connect the primary fibres some- 

 times horizontally and sometimes vertically. The incurrent orifices in both varieties are 

 small and plentifully scattered over the surface, which has a peculiarly dense and smooth 

 aspect on account of the prevalence of this connective tissue. 



Spongelia rectilinea Hyatt. 



Variety 'h'regidaris. One of the specimens examined (PI. xvii, fig. 15rt) is a sessile, but 

 irregular mass, which may have been two complete branching colonies which have co- 

 alesced, or a very porous colony with a double base. The hollows running through the mass 

 are so regular that they might have arisen in this unusual way, though it is more likely 

 that they are the natural accompaniment of the growth of the mass. The principal char- 

 acteristic is the smoothness of the surface of the skeleton and the distinctness of the pri- 

 mary fibres in the interior, which are loaded with pebble dust. The mesh is coarser than 



> This species is respectfully dedicated to Prof. W. G. interest he Las shown in this Memoir, and the important 

 Farlow, to whom the author feels deeply indebted for the assistance he has given. 



