| OCR Text |
Show 528 DR. J. E. GRAY ON SPONGES. [May 9, gated cylindrical thread-like spicules placed in a longitudinal, and oblique direction, crossing each other, and forming a more or less regular network. Sarcode scattered with stellate spicules, with the rays more or less divided. A. Tube formed of longitudinal and transverse bundles of filiform spicules, intersected with more slender oblique series of spicules, and strengthened externally with transverse or oblique raised ridges, the upper ridge forming a fringe between the end of the tubes and the irregularly netted lid; the base of the tubes surrounded with free filiform spicules, barbed at the end. 1. EUPLECTELLA. The tubes regular, gradually wider above, formed of regular longitudinal and transverse bundles of filiform spicules, which are crossed in an oblique direction with more slender fascicules or separate filiform spicules, and strengthened externally with transverse or oblique elevated ridges ; the upper ridge forming a fringe at the top of the tubes, between the edge of the tubes and the irregularly netted lid. Sarcode thin, studded with many-rayed stellate spicules, with long simple or trifid rays, or with short rays divided at the end into several converging ra}'S, forming a bell-shaped series. The fringe on the end of the tube, between it and the lid, is only found in the perfectly grown sponges; it is very small in the specimens of E. aspergillum that are not quite of the normal form-that is, I certainly believe them to be) of the Jardin des Plantes are very closely allied. It is not easy at first to catch a good microscopic character. Still there is a difference in the form of the small spicules especially. These two species are, however, utterly different from our Euplectella aspergillum. It would be impossible to put the three even in the same genus. In the French species the network of the wall is formed entirely of perfectly free spicules, very long, simply interwoven, never anastomosing, held together by sarcodic substance alone, and perfectly easily shaken separate by a needle or a hair-pencil in a drop of water. The spicules are exactly of the same type as those of Hyalonema, and are netted together precisely in the same way; in fact the French species would fit m u ch better into the genus Hyalonema than into Euplectella. They will not go into either genus, however, and either you or I must concoct a special generic name for them. " Eup. aspergillum, again, reminds one strongly of the work you must have often seen-ships, baskets, & c , made of spun-glass, by heating and netting it in and out in all directions, attaching constantly the various points of contact. Thus, while aspergillum is made quite rigid, the French species are absolutely flexible, only firm enough to maintain their form. " It seems to m e that we have now a series forming a very remarkable group, graduating through Aphrocallistes ?, Hyalonema, the French genus, Euplectella (aspergillum and cucumer), into Iphiteon and Dactylocalyx. In these the form is very different certainly; but the general plan of the small free spicules is the same, and the interlacing siliceous tubing is very much as in Eup. aspergillum. " Schultze's proposed group ' Lophospongiae' cannot stand. It is founded upon the long free spicules merely, and would only contain Hyalonema and Euplectella, excluding Aphrocallistes and the French genus, which seem to m e most characteristic members of the series. " By-the-by could you give m e a shred of Aphrccallistes, I should like to compare the small spicules." |
