The Annals and magazine of natural history; zoology, botany, and geology . Habro-dictyon the most common sarcode-spicule is the floricomo-hexradiate of Bowerbank (PI. IV. fig. 1 e); and the sameform occurs abundantly in Euplectella aspergillum. The coronato-hexradiate stellate form figured by Bowerbank(Brit. Spong. vol. i. fig. 195) seems to be the central star ofone of these without the cm-ved processes. Associated withthis type, we have in Habrodictyon multitudes of extremelyminute hexradiate spicules, variously armed and feathered,and scarcely distinguishable from the ordinary spicules of t
The Annals and magazine of natural history; zoology, botany, and geology . Habro-dictyon the most common sarcode-spicule is the floricomo-hexradiate of Bowerbank (PI. IV. fig. 1 e); and the sameform occurs abundantly in Euplectella aspergillum. The coronato-hexradiate stellate form figured by Bowerbank(Brit. Spong. vol. i. fig. 195) seems to be the central star ofone of these without the cm-ved processes. Associated withthis type, we have in Habrodictyon multitudes of extremelyminute hexradiate spicules, variously armed and feathered,and scarcely distinguishable from the ordinary spicules of thesarcode of Hyalonema. The spicule which in the series de-parts most from the hexradiate form is the wonderful doublegrapnel of Hyalonema; but, although its ends are split up intocurving flukes, in the very middle of the shaft the cross-canals Prof. W. Thomson on the Vitreous Sponges. 123 betray the universal type. One set of the sarcode-spicules ofAphrocalUstes^ is almost identical with the furcated spiculatedbiternate spicule figured from Farrea occa (British Sponges. vol. i. fig. 199), but more spiny. I am afraid to name this formbut i am sm-e it would be highly suggestive to Dr. Bower-bank. 124 Prof. W. Thomson on the Vitreous Sponges. Another set from ApJirocallistes are especially interesting(woodcut, a): they consist of a lengthened shaft ending ina small expansion, from which spring four equal branches,each terminated by a little knob. No doubt these are theseparated branches of a complex hexradiate spicule closely re-sembling those figured by Bowerbank (British Sponges, vol. 190-192) from species of the penultimate genus of ourseries, Dactylocalyx. General Structure of the Sponges. The netted walls of the two species of Habrodictyon areformed of a loose open network of fascicles of comparativelyshort fusiform spicules, the fascicles loosely bound together bythe soft sarcode. The bundles curve irregularly in all direc-tions, so that the network is quite irregul
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