REPOET ON THE MONAXONIDA. 231 



massive external form and the shape of the megaselera. Spirastrella cunctatrix, 

 Schmidt/ approaches it in spiculation, but in that species both megaselera and 

 microsclera are of decidedly more robust growth, and the megaselera arc usually very 

 distinctly tylostylote and quite straight, whUe the form of the spined spii-ulse is also 

 different. Spirastrella massa is also remarkable for the great irregularity in the shape 

 of the megaselera ; these are often very abnormal in appearance and may even 

 (though rarely) become oxeote ; this should perhaps be connected with the apparent 

 interchangeability (in different species) of the stylote and oxeote spicules, and with 

 the instability in the condition of the ends of the oxeote in Latrimculia (?) acerata, 

 nobis. 



ioca%.— Station 162, April 2, 1874; lat. 39° 10' 30" S., long. 146° 37' 0" E.; Bass 

 Strait; depth, 38 fathoms; bottom, sand and shells. Two large pieces. 



Spirastrella solida, Ridley and Dendy (PL XLI. fig. 7; PI. XLV. figs. 13-13e). 



1886. Spirastrella solida, Eidley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 491. 



Sponge (PL XLI. fig. 7) erect, sessUe, lobate or digitate ; consisting of a broad base, 

 containing a large amount of embedded foreign matter, from which arise broad, fleshy- 

 looking lobes, the larger of which have each one osculum (1 sometimes more) at the summit. 

 Height of the largest .specimen 88 mm.; breadth at base 54 mm. Colour in spirit 

 light yellow. Texture very firm and hard throughout, excepting immediately around 

 the larger canals, where there is a well defined zone of soft, gelatinous, transjjarent tissue 

 enclosing and following the course of the canal. In the wider parts of the exhalent 

 canals, near the summits of the lobes, the same kind of tissue forms well defined circular 

 diaphragms, each with only a small aperture in the centre. Surface rather lumpy and 

 uneven, almost glabrous in appearance yet harsh to the touch. Dermal membrane 

 difficult to distinguish as such, being very heavily laden with the characteristic 

 microsclera. Oscula few in number, but of fair size, occurring ( ? singly) at the tops of 

 the lobes. Pores irregularly but very plentifully scattered over the general surface of 

 the sponge; they are round openings about 0"044 mm. in diameter. 



Skeleton. — Consisting throughout of an extraordinarily dense, but quite irregular 

 reticulation of interlacing tylostylote spicules ; no spiculo-fibre. At the surface are loose, 

 radiating brushes of smaller, straight, tylostylote spicules, whose apices j^roject for a short 

 distance beyond the surface. 



Spicules. — (a) Megaselera; (1) the main spicules, almost straight, fairly stout 

 tylostyU (PL XLV. fig. 13), with well developed subglobular heads and rather blunt 

 apices; size about 07 by 0'19 mm. (2) The spicules of the surface brushes; nearly or 

 quite straight, slender tylostyli with well developed subglobular heads and sharply pointed 



^ Spongien d. Kiiste v. Algier., p. 17. 



