Sponges from South Australia. 113 



It is to these two kinds of Spirastrella that I have long- 

 since alluded as coming both from the south coast of Australia 

 and the Mauritius {' Annals,' 1882, vol. ix. p. 351). 



Again, while the adult form of Spirastrella cunctatrix is 

 more or less massive, pyramidal, and sessile, and has a 

 comparatively open fibro-reticulate structure in the interior 

 and a pinkish or lilac, more or less brown colour externally 

 in the dried state ; that of the variety is compressed, erect, 

 flabellate, lobed, and stipitate, with a comparatively compact 

 structure in the interior of a chalky consistence and an 

 " orange-red colour " when fresh, but in its dried state light 

 ochre-yellow throughout. Lastly, the surface of Spiras- 

 trella cunctatrix presents slight scar-like elevations in juxta- 

 position, which, becoming more and more prominent towards 

 the lower part, may pass from simple elevations into prolife- 

 rous growths or processes at the base, while the surface of the 

 variety is uniformly smooth, especially towards the stem. 



Thus contrasted, so far as my observation extends, let us 

 pass to a brief description of the typical species as well as the 

 variety, both of which occur in Mr. Wilson's collection. 



11. Spirastrella cunctatrix, Sdt. 



Massive, compressed, sessile, elongated, convex or arched 

 longitudinally, wider below than above, where it terminates in 

 a longitudinal narrow space, bounded throughout by a slight 

 elevation of the sides, which thus converts it into a kind 

 of trough or gutter. Consistence firm. Colour, when fresh, 

 "tawny brown," now lilac dark-grey or lilac dark-mouse-colour. 

 Surface consisting of a smooth dermis covering the slight 

 elevations of the subjacent structure, which are in juxtaposition, 

 more or less uniform in size and shape, scar-like, subsiding 

 to a common level upwards, increasing in prominence down- 

 wards, until at the base they pass into enlarged proliferous 

 growths. Vents numerous, coniined to the longitudinal space 

 or trough which forms the summit. Spicules of two forms, 

 viz. : — 1, skeletal, pin-like, of which the prevailing shape of 

 the head is subglobular, varying to simple acuate (as is usually 

 the case with this spicule wherever it occurs), shaft fusiform, 

 finely pointed, 200 by 2^-6000ths in. ; 2, flesh-spicule a spini- 

 spirular of four bends, varying under 12 by 3-6000ths in., 

 including the spines, shaft without the spines about l-6000th 

 in. in diameter. Structure from without inwards consisting of 

 a tougii fibrous dermis, which covers a thick compact layer 

 plentifully charged with the tlesh- spicules of the species, 

 passing gradually into a less compact interior mottled grey and 



