Knowledge of the Spongida. 349 



more slender and the stellate often without appreciable body 

 or central nucleus (PI. XIV. fig. 2 7 f, &c). 



In "Subsection 1, 6," the cortex becomes more defined by 

 the addition of the bacilliform spicule, which then is the domi- 

 nant element. Its typical form is an obtuse-ended acerate 

 more or less inflated in the centre and microspined throughout 

 (PI- XIV.^ fig. 3,#), but may vary from elliptical up to that 

 condition in which it is cylindrical or absolutely straight (that 

 is, without curvature or central inflation, and thus essentially 

 a microspined bacillmn) , while, abnormally, it may pass from 

 a uniaxial into a polyaxial form like that of a stellate, viz. 

 when the primary cell takes to elongating itself in more 

 directions than one (PI. XIV. fig. 3.ttt). In Ecionemia 

 acervus y Bk., it is stated to be " fusiform-cylindrical," 

 averaging 1 -3000th inch in length by l-10,000th in its greatest 

 transverse diameter j and in Ecionemia densa, Bk., it is re- 

 presented of an elliptical form, covered with minute tubercles 

 instead of spines (Proc. Zool. Soc. 1873, pi. xxx. figs. 1-6 

 and 7-14 respectively). Both these species are in the Museum 

 of the Royal College of Surgeons, and are stated to have come 

 from the " Fiji Islands ;" while Schmidt, who examined the 

 former in 1866 

 found it to be a species 



established in 1862 (ib. p. 46), and therefore called it ".Std* 

 letta" Again, the bacilliform spicule is present in Ecionemia 

 pfondtrosa, Bk., from Guernsey, which is identical with the 

 species on the sea-shore rocks here (Burleigh Salterton, S. 

 Devon), that I subsequently described, of course in igno- 

 rance of this identity, as Stelletta aspera (' Annals,' 1871, 

 vol. vii. p. 8, pi. iv. fig. 12) — but in such a modified form, on 

 account of the length of the spines, that it looks very much 

 like a " spinispirula," and is actually described as "elongo- 

 stellate" byDr.Bowerbank, who, in his u Terminology" (Mom 

 B. S. vol. i. fig. 35), uses this name for the spinispirula, of 

 Tethea muricata. But although the shaft is evidently spiral 

 in the latter, I have never, from its minuteness, been able to 

 satisfy myself that it is so in the former, although I incline to 

 this view. Be it as it may, however, it matters very little ; for 

 although this would bring it nearer to Ecionemia compressa, 

 as we shall see by-and-by, the conventional line of separation 

 must be drawn somewhere; and the more important part of 

 the spiculation in Ecionemia ponderosa allies it most nearly 

 to Stelletta, as Schmidt has stated. It is present in Stelletta 

 Hellerii, Sdt., from the Adriatic, also in an undescribed species 

 in the general collection of the British Museum (no. 302, re- 

 gistered 40. 1. 1. 1), said to have come from W. Africa; also 



(Spong. Adriat. Aleeres, 2nd Suppl. p. 12), 

 species of the genus " Stelletta" which he 



