496 Transactions of the Society. 



with. Were we only to see a fragment of the brown substance 

 from the interior of the coral in its dried state, the homogeneous, 

 fibreless character of the then gum-like sarcode, although charged 

 with spicules, might induce one to think that it belonged to the 

 Gumminida, and so, provisionally, I called the species described in 

 the 'Annals' (I. c.) Gummina {mendose, Corticium) Wallichii; 

 but Dr. Millar's discovery undoubtedly proves it to be an " exca- 

 vating sponge," so the generic name " Gummina " will still have 

 to be changed to meet this in the way that will presently be 

 mentioned. 



The spiculation in Aledona MiJlari (it is the only form that I 

 can give to " Alecto," which has been so often used, and as often 

 transformed, for other things), is somewhat different from what I 

 have figured of Gummijia Wallichii (I c), and these differences 

 are as follows: — In the skeleton-spicule (No. 1) the tubercles are 

 conical or divided at the extremity, and not smooth, round, inflated, 

 flattened and undivided as in G. WaUichii ; while the earlier 

 untubercled form of this spicule (pi. xxix. fig. 6, op. et I. c.) 

 coming so near in size to the large tubercled form, I have not seen 

 in A. Millari ; but there are much smaller ones, viz. No. 2, that 

 might stand for this, and amongst these every grade in form 

 between the large skeleton-spicule No. 1 and the minute flesh- 

 spicule No, 4. So that when compared with the spiculation of 

 Gummina WaUichii as a standard, the whole of the former, cha- 

 racterized by their extreme variability, can only be considered as 

 derivative from the latter, and hence my opinion that Alectona 

 Millari is only a variety of Gummina Wallichii. 



At last, then, the nature of this sponge has been discovered, 

 whose singularly beautiful skeleton-spicules created such a desire to 

 know their origin ; and thus, as just stated, it becomes necessary to 

 change the name " Gummina " to the generic one of " Alectona." 

 With this, too, it seems desirable, now that three distinct genera 

 of " excavating sponges" are knoun, the whole should, from this 

 distinguishing peculiarity, be placed under one family, to which 

 hereafter it is very possible that more may be added. To effect 

 this I would propose the following classification, viz. : — 



Order VI. HoLorvHAPHiDOTA. 

 Family. Eccoelonida.* 

 Char. Sponges burrowing in hard calcareous objects, organic 

 and inorganic, communicating with the exterior through small 

 fenestral openings ; sarcode fibreless, but spiculiferous. 



Gen. 1. Cliona, Grant, 1826. 

 Possessing a pin-like spicule, with or without subskeleton and 

 flesh-spicules. riesh-sj)icule sinuous, smooth, or microspined. 



* iKKoiKaivw, to hollow out. 



