DIC'TYOSPON'GID1E (Neo-Lat. nom. pl.. front Gk. 31Kruov, diktyon. net +G.21-6-y-yos. spongor, eponge). .1 family of usually large. fossil lyssa eine sponges somewhat closely ex isting grass-sponges I Euplectella f • :11141 found in rocks of Lower Devonian to Lower Carbonif erous ave. but chiefly in those of Upper De vonian ave in New York Stale. In form these spong..s vary from ovals'. cylindrical, and pris matic 11) They have a large cen tral cavity. and thin walls in which tilt' spieules formed a skeleton of great regularity. hill 1 he '411111 ee Of t he ornamented by a network of tine reetangular meshes. As the sponge substance itself was decomposed and the siliceous spicules dissolved during the proc esses of fossilization, these organisms appear at present as of the original organic matter, imbedded in shalt' sandstones, and their lure is indicated by the impressed lines upon their surfaces. and in /1111• by iron oxide Iliutonittl which OCC111)bs the cavities once tilled organic tissue or SOMP of .piaigy. have very form with smooth others are radially or transversely rilthed, and still others are spiny or nodulose, while a few have pouched nodes upon their SOT f 111 the region where these fossil sponges have been found in greatest abundance-11a melt-. in
Ilegan•, f'attaraloms. and Stenben •tainties of New Ytirk Stale--thel occur in or sandstones in •itell 111:11111(•* as Its indicate that they lived often in extensive colonies on sandy or ninthly hottoins. and I hvy are not a. a rule associated with any considerable 111111111er of other kinds of fossil organisms. nit- earliest species, Dietyospongia Danby i. front the I pper Ludlow rocks of England. has a simple. sul,ovate form. The more ornamented forms appear in the Upper Devonian and lamer 'Carboniferous rocks. The principal genera are Dietyospongia, Upliantamia, 1 :11111 TilysaMichelCa of 111e •liemung roeks. and Pltragmodietya and Physospongia of the Keokuk: group of Lower Carboniferous age. About 2.00 species are known. of which number scarcely more than half a dozen are European. .1n elegant monograph, with tine lithographic plates of these fossil sponges. by James I1a11 and .1. Clarke a-. "A on the Paleozoic Reticulate Sponges of the Family Dictyospongida.," in Memoirs of (lie (sir fort; Stoic 11u.scum of nm/ History. vol. ii. (Albany, !tins). See Scom;E: SPONGIOZO.k.