88 RECORDS OF THE AUSTRALIAN MUSEUM. 



whole forming a very irregular honeycomb -like sponge, 100 mm. 

 in height, 80 mm. in breadth, and 27 mm. in thickness. The 

 specimen has been longitudinally bisected, and is now about half 

 its original size. The surface is hispid throughout, and numerous 

 small oscula are scattered in the deeper parts at the bases of 

 the lamellae. Texture soft, tough, and slightly elastic. Colour, 

 yellowish-gray. 



Skeleton reticulate, consisting of main and secondary fibres, the 

 former from 01 to 0'15 mm. in diameter, separated by oval or 

 elongated spaces, from 015 to 3 mm. in diameter, and cored by 

 loosely arranged smooth styli ; they are invested with a small 

 amount of spongin. The connecting fibres are about 0'025 mm. 

 in diameter, and contain a few smooth, ill-disposed styli. All the 

 fibres are remotely echinated by scarce smooth, or nearly smooth 

 styli. A few exhibit incipient spines, which give the spicule a 

 slightly sinuous outline. 



Megascleres — (a) Smooth or very minutely spined styli. Size — 

 006 by 0'007 mm. (6) Smooth styli of various dimensions. Sizes — • 

 0-3 by 0-008, 0-17 by 0-005, and 0-15 by 0-0025 mm. 



The spicular measurements in the original diagnosis are: 

 Smooth (?) echinating styli, 0-5 by 0-005 mm., and the styli in 

 the fibres 0-14 by 0-006 mm. 



The prevailing features of this form are those of an Echino- 

 clathria, in which genus it might find a place when better 

 material is available. 



Clathria arborea, Lenden/eld, sp. 

 (Plate xi., figs. 15, 15a). 

 Plectispa arborea, Lendenfeld, Aust. Mus. Cat., xiii.. Sponges, 

 1888, p. 226. 



Several examples of this common species are in the collection. 

 The specimens are generally reticulately branched in one plane. 

 The branches are compressed, and vary from 3 to 10 mm. in 

 diameter. The spaces between the coalesced branches measure 

 from 5 to 20 mm. or more, and are very irregular in shape, vary- 

 ing from round to elongate. Surface rough, covered throughout 

 with warty elevations and numerous small circular oscula-like 

 apertures. Texture firm, tough, and elastic. Colour when alive, 

 brick-red ; in the dried state, light stone. The main fibres are 

 cored with numerous smooth styli, about 0-185 mm. long, and 

 0-008 mm. in diameter ; abundant subtylostyli occur throughout 

 the sponge, they are 0*25 mm. in length and 0002 in breadth. 

 Echinating styli few, rapidly tapering, acute and spined through- 

 out. Size — 0-085 mm. long, and 0-006 in diameter. 



In the description of this species,^"' the fibres are stated to be 

 echinated by "very scarce smooth styli." I have examined the 



19 Lendenfeld— Aust. Mus. Cat., xiii., Sponges, 1888, p. 226. 



