344 DR. J.S. BOWERBANK ON SILICEO-FIBROUS SPONGES. [May 13, 
case is by no means a new fact, as there are abundant instances of 
similar close alliances existing among the recent Australian sponges 
and those of the chalk formation of England ; and amongst the most 
prominent are the existing representatives of Choanites and Ventri- 
culites. 
ALCYONCELLUM SPECIOSUM, Quoy et Gaimard. 
Luplectella aspergillum, Owen, Trans. Zool. Soc. iii. p. 203. 
Luplectella cucumer, Owen, Trans. Linn. Soc. xxii. p. 117, pl. 21. 
Sponge sessile, cylindrical, more or less curved, enlarging pro- 
gressively from the basal to the distal extremity; upper portion 
furnished with numerous sharp ridges of interlacing fibres disposed 
diagonally and somewhat symmetrically ; apex truncate, closed by a 
coarse, ventricose, fibrous network, and encircled by a strongly pro- 
duced fibrous ridge or frill. Base furnished with numerous fasciculi 
of large and long prehensile spicula projected downward ;_spicula at- 
tenuato-quaternate, barbed alternately for about one-third of their 
length from the distal extremity. Oscula congregated, terminal. 
Pores congregated ; inhalant apertures symmetrically equidistant, 
disposed in lines radiating from the base to the apex of the sponge. 
Dermal membrane abundantly spiculous; spicula acerate, long and 
slender, fasciculated; fasciculi compact, disposed in radiating or 
parallel groups. Skeleton symmetrical: primary lines radiating from 
the base to the apex, equidistant; secondary lines at right angles to 
the primary ones ; interstitial structures interlacing diagonally. Spi- 
cula of the membranes—interstitial spicula rectangulated attenuated 
hexradiate, short and stout, rarely completely developed; also at- 
tenuated rectangulated triradiate apically spined. Spicula of the 
sarcode trifurcated attenuato-hexradiate stellate, and floricomo-hex- 
radiate,yery minute. 
Colour amber-yellow ? 
Hab. Philippine Islands; Island of Bohol, 10 fathoms (Mr. Hugh 
Cuming) ; Island of Zebu, about 24 fathoms (Mr. R. Geale). 
Examined in the skeleton-state. 
There are several indications of a close alliance between Aleyon- 
cellum and Dactylocalyx, Iphiteon, and the other genera of well 
developed siliceo-fibrous sponges. 
The structure of the skeleton-fibres and their habit of anasto- 
mosing whenever they touch each other are precisely the same as 
they are in the genera I have named. The floricomo-hexradiate stel- 
late retentive spicula of Alcyoncellum, Plate XXIV. fig. 11, and the 
beautiful spinulo-multifurcate hexradiate spicula of Iphiteon callo- 
cyathes, Plate XXIII. fig. 7, are so peculiar in their forms, and so 
similar in the mode of their constructicn and relative positions in 
the two sponges, as to at once lead us to the conclusion that the two 
species are in very close alliance with each other. A similar close 
alliance is indicated by the comparison of the slender attenuated rec- 
tangulated-hexradiate interstitial spicula of Aleyoncellum (Pl. XXIV.. 
fig. 9) and those of Iphiteon callocyathes represented Plate XXIII, 
