SPONGES.-HALLMANN. iqo 



The remaining specimens of the collection — the non-typical 

 specimens — fall into three groups. The first group is repre- 

 sented by a single specimen (Z. 935) which in texture and 

 appearance is quite unlike the typical specimens, and which, 

 on that account, might have been expected to yield tangible 

 points of difference in the spicule characters. Except, how- 

 ever, that the acanthostyles are more spiny (fig. c'), and that 

 the tylosis of the auxiliary spicules is more strictly terminal 

 ;(fig. c), there is nothing to distinguish its spicules from those 

 of the type-specimen. These differences are not so great that 

 they might be considered as due to individual variation. 



The second group is represented by the specimen (Z. 939) 

 which received particular mention at the outset, on account 

 of its larger size and simpler form. Whilst in this also, the 

 smooth spicules show a correspondence in size with those of 

 the type-specimen, the tylosis of the accessory spicules is 

 much reduced, and, for the majority of them, inappreciable; 

 furthermore, the acanthostyles (fig. d) are markedly larger, 

 often 9 ^ in diameter, and, though usually between 75 and 

 85 ji long, may actually attain to 105 }i. This group may, for 

 the present, be regarded as a sub-variety. 



In the third group, of which a specimen (Z. 940) bearing a 

 close resemblance in texture and even in general appearance to 

 the large specimen of the second group, may be quoted as an 

 •example — the spicule dimensions again accord with those of 

 the type, except that the acanthostyles (fig. e) are slightlv 

 stouter, 8 to 9.5 /i in diameter, and more abundantlv spined, 

 like those of the second group. But in one respect at least, 

 the members of the present group differ from the others of the 

 variety — the auxiliary spicules are simply stylote, i.e., entirely 

 devoid of any trace of basal enlargement ; they ought, accord- 

 ingly, to be regarded for the present as constituting a second 

 sub-variety. 



Loc. — Port Jackson and neighbourhood (Austr. Mus. Coll.). 



Rhaphidophlus typicus, var. steli.ifer, var. nov. 



(Plate xxvii. , and fig. 41.) 



This variety is represented by a single specimen. The 

 sponge is stipitate, flabelllform, with lobate margin, and with 

 a couple of digitiform upgrowths flanking the lamina. It 

 measures 300 mm. in height, 160 mm. in breadth, and about 

 6 mm. in diameter. Scattered at intervals over the surface 

 are radiate groups of short obscure ridges forming "asterisks" 

 35 to 20 mm. in diameter. Towards the distal margin, the 



