Astylospongida"! and Auomocladinn. 273 



indicate the point from wliicli the brandies belonging to a 

 skeletal element radiate. On careful examination 1 have 

 only been able to find one kind of node, and think I may 

 assume that all of them have originated in the same way 

 from the union of the furcate ends of several skeletal elements. 

 From thisj however, it follows that the latticed skeleton of 

 the Astylospongidce does not consist of sexradiates fused 

 together^ hut of simjile rods, both ends of which are branched 

 and^ hy union with from six to nine other rods^forni the charac- 

 teristic nodes. Hence the Astylospongidce, as they contain no 

 sexradiates, cannot belong to the HexactineUidce. 



If we look round the other orders of Sponges it is only the 

 Lithistidai that possess skeletal corpuscles with radiciforui 

 branched ends. The external form, the dense, stony nature 

 of the skeleton, and the complicated canal-system of the 

 Astylospongidee also point towards the Lithistidee. Of the 

 four families distinguished among the Lithistidaj, the llhizo- 

 morina, Megamorina, and Tetracladina cannot come into 

 consideration, as the form of tlieii* skeletal corpuscles is quite 

 different. 



Dr. Hinde has therefore very justly indicated the Anomo- 

 cladina as the group with which the Astylospongidee can best 

 be compared. The typical genera here are Melonella, Cylin- 

 drophyma, and Mastosia ; with the first Astylospongia almost 

 exactly agrees in its canal-system. 



The investigation of the Anomocladina formerly offered 

 me greater dithculties than that of the other Lithistidai. 

 Thus it is very seldom that we find well-preserved specimens 

 fitted for microscopic examination ; the skeleton is almost 

 always converted into calc-spar or deformed by subsequent 

 silicification. The correct figures of the skeleton of Cylindro- 

 l^hyma (' Studien,' li. pi. v. fig. 6) show a very irregular 

 latticework with thickened nodes, which, however, sometimes 

 acquires a more regular appearance and then resembles the 

 network of a Hexactincllid (see my figures, I. c. pi. v. fig. 6 d 

 & fig. 7, as also the slightly enlarged figures in Quenstedt's 

 ' Petrefactenkunde Deutschlands,' iSchwamme, pi. cxxi. 

 figs. 3 .« &L Ay). I formerly regarded the Anomocladine 

 skeleton as a latticework of which the elements consist of 

 four or more smooth arms meeting together in a thickened 

 centre and branched at their extremities. 



In a short memoir upon two new genera of Sponges from 

 the Upper Jura of Sontheim (Jahrb. f. Min. &c. J 883, ii. 

 p. 59) Mr. G. Linck describes, under the name of Didyrno- 

 si)hcera, an Anomocladine form supposed to be new, but 

 which, according to a prep.iration for which 1 am indebted to 

 Ann. & Mag. N. Hist. Ser. 5. To/, xiv. 21 



