480 ASTROSCLERA WILLEYANA, THE TYPE OF A NEW FAMILY OF SPONGES. 



The skeleton is rigid and built up of elements consisting of aragonite, contained 

 in an organic basis, and having a fibrous structure disposed in lines radiating from a 

 point in the centre of the element. The elements are formed in single cells and are 

 at first free and spherical, the}' may pass through a spheraster stage, and are ultimately 

 built together, becoming polyhedral by mutual apposition into a compact skeleton from 

 which the soft tissues are excluded. 



The skeletal canals permeate the skeleton freely branching and anastomosing, and 

 open at the pores on the surface. In the later stages (?) of growth, large trunks of 

 the skeletal canal system are formed, which open at the larger f)ores at the surface. 



The soft tissues form a layer at the surface, and are contained in the skeletal 

 canals. The ciliated chambers are minute (18 by 11 /i) and both afferent and efferent 

 systems of canals are long and branched. It is probable that the larger efferent 

 trunks run in the large skeletal canals. There is no common atrial cavity, and the 

 canals communicate with the e.xterior by pores in the gelatinous layer covering the upper 

 surface. 



The larva belongs to the par enchy inula type. 



Astrosclera ^villeyana occurs at depths of 3.5 to 40 fathoms at Sandal Bay, Lifu, 

 Loyalty Islands, and at a depth of 100 fathoms on the outer slope of Funafuti, Ellice 

 Islands. 



The name of the genus Astrosclera is descriptive of the star-like arrangement of the 

 fibres in the skeletal elements, and I propose the specific name ivilleyana in commemo- 

 ration of Dr Willey's labours among the islands of the Western Pacific, carried on with 

 persistence and enthusiasm and more than once at no small personal risk, in pursuit 

 of the object which he had in view. 



In conclusion, I wish to express my thanks to the authorities of the British Museum 

 for allowing me to examine the Funafuti specimen of Astrosclera ; to Dr G. J. Hinde, F.R.S. 

 for naming my Pkaretrones from the Tyrol, and for his kind assistance in other ways ; 

 and to Mr Hutchinson of Pembroke College, for his careful determination of the physical 

 and chemical properties of the specimens of the skeleton of Astrosclera which I placed 

 in his hands. 



