76 RECORDS OF THE AUSTRALIAN MUSEUM. 



The spicules are slightly curved oxea, which are abruptly 

 narrowed at the ends, but not very sharp pointed. Size — 075 by 

 00075 mm. 



Three specimens from Lake lllawarra, and two from Tuggerah 

 Beach. 



Arenochalina, Lendenfeld. 



Arenochalina mirabilis, Lendenfeld. 

 (Plate X., fig. 7). 

 Arenochalina mirabilis, Lendenfeld, Zool. Jahrb., ii., 1887, p. 821, 

 pi. xxvi., fig. 70 ; pi. xxvii., fig. 28 ; id., Aust. Mus. Cat., xiii., 

 Sponges, 1888, p. 103. 



This species is common on the coast, and is represented in the 

 Museum collection by a fine series of specimens. Owing to the 

 very open character of the mesh, the ground substance is easily 

 washed away, and most of the examples met with present a 

 washed out skeleton not unlike some species of Thorecta. The 

 habit is subject to great variation. The sponge may consist of a 

 single, elongate, finger-like lobe, about twice as broad as thick. 

 One example is 220 mm. in height, 40 mm. in its widest part, 

 and L5 mm. in its lesser diameter. Some individuals are hand- 

 shaped, having a short peduncle and a palmatified lamina. One 

 specimen of this kind measures 230 mm. in height, 210 mm. in 

 breadth, and the basal half from 10 to 12 mm. in thickness. The 

 distal branches are flat, and are somewhat variable in breadth 

 and length, but uniform in their narrow diameter. Abundant 

 oscula occur on the lateral margins, their diameter ranging between 

 2 and 3 mm. Texture in the dried state, firm, slightly brittle, 

 and not very elastic. Colour when alive, reddish-purple ; when 

 washed, gray with a rusty or purplish tint in the deeper parts, 

 especially near the base. 



The skeleton is accurately described in the Catalogue of Sponges, 

 and a portion is figured in the Zool. Jahrbiich., on plate xxvii., 

 fig. 28. There is, however, one serious error in the account of 

 the spicules, they are described as "oxea 0*02 mm. long, and 

 0'004 mm. in thickness." All the spicules seen in situ in the 

 secondary fibres proved to be straight styli, with a small rounded 

 base and an abruptly pointed apex. Size — 0'19 to 0*02 mm. by 

 0-004 to 0-005 mm. 



Although this species is enumerated in the Catalogue of Sponges, 

 there is no example named by the author. The name occurs three 

 times in the manuscript list, each time with a query (Nos. 136, 

 275, 276). Upon examination, the specimens proved to be two 

 examples of Hircinia caliculaia, Lendenfeld, and one Siphono- 

 chalina intermedia, Ridley and Dendy. The latter bears the 

 number 274 in the list, which may account for the mistake. 



There are two specimens in the Fisheries' donation from 

 Tuggerah Beach. 



