]873.] DR. J. S. BOVVERBANR ON THE SPONGIAD.E. 7 



membranes — tension-spicula fusiformi-acerate, small and few in 

 number ; retentive spicula attenuato-stellate, radii long and slender ; 

 and cylindro-stellate, radii short and stout, minute. Ovaria globose, 

 slightly depressed. 



Colour cream-yellow in the dried state. 



Hab. Martinique and Porto Rico, Antilles {Lamarck) ; Island of 

 Dominica, West Indies {Dr. Fleming). 

 Examined in the dried state. 



The type specimen of the genus is preserved in the Museum of 

 the Jardin des Plantes at Paris. It is subglobose in form, with 

 numerous slight and irregularly shaped elevations dispersed over 

 its surface ; and it is from 4| to 5 inches in diameter. 



There is one large oscular area about an inch in diameter, some- 

 what sunk beneath the general surface, and contained within a well- 

 defined marginal ring, the greatest diameter of which is about two 

 inches. Nearly the whole of the radial fasciculi of the skeleton have 

 apparently been scooped out, to facilitate the drying of the speci- 

 men, through a large hole in the sponge about 1 1 inch in diameter ; 

 and so effectually has this operation been performed that the sides 

 of the sponge do not appear to exceed about half an inch in thick- 

 ness in its dried condition. 



There is a second specimen of apparently the same species of 

 Geodia in the French Museum, somewhat larger than the type one, 

 varying from 5| to 6 inches in diameter. The form is nearly the 

 same as the first, but the surface more prominently tuberculated, 

 and more conical in form ; but these slight variations are of no 

 importance as specific characters. This specimen, like the type 

 one, has a single nearly circular oscular area, with a Well-defined 

 marginal ring, the diameter of which is about 1 \ inch ; it has also a 

 large hole about 1| inch in diameter; and the interior substance 

 of the sponge has evidently been removed to facilitate the drying 

 of the specimen. These specimens were hitherto considered to be 

 the only two known. Through the kind assistance of Professors 

 Milne-Edwards and Valenciennes, I had an opportunity of thoroughly 

 examining their organization; and from them, and from a third one in 

 the possession of Dr. Andrew Fleming, son of the late veteran natu- 

 ralist, Professor Fleming of Edinburgh, I have constructed the above 

 specific characters. 



TbeosculainDr. Fleming's specimen are so small as to be scarcely 

 discernible without the aid of a lens. On one side of the sponge 

 they are dispersed ; but on other parts they are congregated in small 

 groups, but not especially so in the depressions of the surface. They 

 are each furnished with a contractile membrane ; some of them were 

 completely closed, while others were more or less in an open condition. 

 The difference in the disposition of the oscula in Dr. Fleming's speci- 

 men and those in the French Museum, may probably be accounted for 

 by the younger and less-developed state of the smaller specimen. 



Unfortunately all the three specimens have much deteriorated, 

 apparently by maceration in water, or by repeated washing ; so thai 



