HYATTELLA. 233 



Genus HYATTELLA, n. gen. 



Aulenidae of reticulate, not honeycombed structure, with exten- 

 sive vestibular cavities, which are wider than the septa between 

 them. The thicker connecting-fibres exceed 0*03 millim. The 

 meshes of the skeleton-net are about 0-2 millim. wide. The 

 fibres contain only a small quantity of foreign material. Without 

 proper spicules of any kind. 



Hyattella clathrataj Carter. 



Hircinia dathrata, H. J. Carter, " Eeport on the Sponges dredged up from 

 the Gulf of Manaar, together with others from the sea in the vicinity of 

 Bass Eocks and from Bass Straits respectively, presented to the Liverpool 

 !Free Museum by Capt. H. Cawne Warren," Annals and Magazine of 

 Natural History, ser. 5, vol. vii. p. 366 (1881). 



Irregularly ramified or cup-shaped sponges, which consist of a network of 

 stout, compressed, band-shaped trabeculse. The sponge appears in the form 

 of a massive incrustation, from the upper surface of which short and thick 

 processes arise. These may remain isolated or (and this is the rule in large 

 specimens) they coalesce in many places, thus forming an iri'egular reticula- 

 tion. Very often they join along the whole length to form a continuous wall 

 surrounding a central cavity, and thus producing a cup-shaped form. The 

 sponge attains a height of 200 millim. and more, and a breadth of 180 millim. 

 These sponges are generally erect, much higher than broad, and extending 

 distally, in the case of the caliculate forms, to produce the irregularly lobose 

 margin of the cup, which is always deeper than broad. The digitate branches 

 of the ramose forms are 15-20 millim. thick, and the wall of the cup of the 

 caliculate specimens has a similar thickness. The trabecula) which compose 

 the sponge are 2-5 millim. thick, and the elongate oval holes in the fairly con- 

 tinuous surface, which are disposed longitudinally, measure 2-5 millim. in 

 breadth and 10-20 millim. in length. The vestibular canals which lead down 

 from these holes have similar dimensions. The free margins of the lamellae are 

 not thickened but simply rounded. The branches or the cup-wall are hollow. 

 The central cavity is continuous and uninterrupted, the trabeculse being 

 confined to the external surface. These central cavities are about one third as 

 wide as the pai*ts in which they lie. It will be seen from this that Hyattella 

 clath-ata resembles Aulena gigantea in the structure of its vestibular system 

 very much. The surface is conulated. The conuli are small, about 0-8 millim. 



