1869.] DR. J.S. BOWERBANK ON SILICEO-FIBROUS SPONGES. 67 
zoophytes rather than sponges.” In his ‘ Notes on the Arrangement 
of Sponges (Proc. Zool. Soc. 1867, p. 492) he arranges them as 
sponges; but in his description of his genus Macdndrewia he com- 
mences thus :—“ The coral expanded, cyathiform,” &c. This con- 
fusion of ideas can only be accounted for on the supposition that 
Dr. Gray has really never taken the trouble to ascertain the struc- 
tural characters of the specimens that have been so many years in 
his possession. 
Although differing to a considerable extent from the general mass 
of the Spongiadae, the primary design of sponge-life in the siliceo- 
fibrous species is in perfect accordance with the great mass of the 
sponges. The external and internal defensive systems are as those 
of other sponges, and their minute organs, as in other species, are 
exceedingly various in form and strikingly demonstrative of their 
specific characters ; in truth they possess in perfection every essen- 
tial organ of the Spongiade. 
Dr. Gray, in his ‘‘ Notes on the Arrangement of Sponges”’ (Proc. 
Zool. Soc. 1867, p. 505), has formed an order to receive the siliceo- 
fibrous sponges, which he has designated Coralliospongia, and he 
thus defines the members of his order :—‘‘ Sponge hard, coral-like. 
Skeleton entirely formed of siliceous spicules, anchylosed together 
by siliceous matter, forming a netted mass covered with sarcode.” 
Prof. Wyville Thomson, in the ‘Ann. & Mag. Nat. Hist.’ for February 
1868, p. 120, in describing the siliceo-fibrous sponges, under the 
head of the “ siliceous skeleton,” says :—“ In Habrodictyon | Aleyon- 
cellum speciosum, Quoy et Gaimard| and Hyalonema the skeleton is 
composed entirely of separate siliceous spicules of various forms, in- 
terwoven in fascicles and connected by the thin sarcode layer, or 
scattered irregularly among the fascicles of spicules. In Luplec- 
tella, Aphrocallistes, Dactylocalyx, and Farrea, certain kinds of 
these spicules are more or less completely fused together, forming a 
continuous anastomosing network.” 
In my observations on Dr. Gray’s ‘‘ Notes on the Arrangement of 
Sponges’’ (Proc. Zool. Soc. 1868, p. 118), I have already pointed 
out the error the author has fallen into in describing Dacty/ocalyz as 
“entirely composed of siliceous spicules anchylosed together by sili- 
ceous matter into a network ;’”’ and I have there stated, and have not 
since seen reason to alter my conviction, that the description of Dr. 
Gray is eminently incorrect, as no one, “I believe, ever saw the termi- 
nations of spicula united into a network through the morbid action of 
anchylosis by means of siliceous matter ;’’ and I may add that I have 
never yet seen a case of the anastomosis of spicula. The normal 
condition of these organs is never to anastomose, however closely they 
may be packed together, while that of siliceo-fibrous structure is always 
to anastomose when they touch each other; and this law is abun- 
dantly illustrated in the fibrous structure of the skeleton of Huplec- 
tella aspergillum, Owen, now so common a specimen in the cabinets 
of collectors. This error of Dr. Gray, regarding the spicular structure 
of Dactylocalyz and other siliceo-fibrous sponges, seems to have been 
unhesitatingly adopted by Prof. Wyville Thomson, and without any 
