252 Transactions of the ere os 
order, are supported by a skeleton composed of interlacing or iso- 
lated, but never of coalescing, elements. 
I append, arranged under their newly-proposed sub-orders, a 
synopsis of all the genera at present known, which must be re- 
ferred to the interesting division of the HzxactineLLipZz. 
Order HEXACTINELLID®. Oscar Schmidt. 
Sponges with a siliceo-fibrous or siliceo-spicular skeleton. Spicula of the 
hexradiate-stellate type invariably present. 
Sub-Ord. I. Coratiiosponcim. J. E. Gray. 
Sponge body supported by an anastomosing or continuous reticulate 
skeleton. Reproductive gemmules entirely membranous, aspiculous (?).* 
Gen, Euplectella, Owen. Gen. Aulodictyon, W.8. Kent. 
Habrodictyon, Wyv. Thomson. Macandrewia, J. KE. Gray. 
Aphrocallistes, J. EK, Gray. Dactylocalyx, Stutchbury. 
Farrea, Bowerbank. Fieldingia, W. 8. Kent. 
Sub-Ord. Il. Canuicisponciz. W.S. Kent. 
Sponge body supported by an interlacing or isolated spicular skeleton ; 
never by a reticulate and continuous one. Reproductive gemmules mem- 
branous, furnished with protective spicula (?).* 
Gen. Pheronema, Leidy. Gen. Lanuginella, Oscar Schmidt. 
Hyalonema (et Carteria), Gray. Vazella, Gray. (Holtenia pars, 
Askonema, W. 8. Kent. O. Sch.) f 
Sympagella, Oscar Schmidt. 
IIl—On a Mode of ascertaining the Structure of the Scales of 
Thysanuradex. By JosepH Brox, F.R.MS., F.RAS. 
(Read before the Royau Microscopicau Socrery, Oct. 12, 1870.) 
I ENDEAVOURED last year verbally to explain my view of the struc- 
ture of the scales found on some of the Thysanuradez, and having 
continued my experiments, and having become more than ever 
convinced of the truth of my views, I think it worth bringing 
before the notice of the Society in a few words. 
I regard the scale as an expansion of the hair, and as designed 
* This last character is not laid down yet as essentially diagnostic, though 
all the evidence so far collected is in favour of it. Dr. Bowerbank records the 
occurrence of membranous, aspiculous gemmules in the genera Dactylocalyx 
and Farrea; while in Lanuginella, as observed in my foregoing remarks, 
forms having the likeness of these bodies, with protective spicula, have been 
detected. We wait for further evidence of their occurrence in this particular 
group. 
x + the generic name of Vazella is proposed by Dr. J. E. Gray in substitution 
for that of Holtenia (H. Pourtalesii, Oscar Schmidt), which is now necessarily 
suppressed; but even if Dr. Thomson’s genus could hold its ground, a new one 
would have to be created for the species referred to it by Dr. Schmidt, that form 
possessing characters entirely different from what obtain in Joltenia (Pheronema) 
proper. 
