222 PALEONTOLOGY OF ILLINOIS. 



their conclusion, yet we may be allowed to express our views to 

 the effect, that the extraordinary resemblance between the co- 

 lumnar arrangement of the spicules in the Anthaspidellidse and 

 "radial pillars" of Actinostroma, etc., is due to homological 

 affinities rather than the result of mere accident. 



With two exceptions all the genera which it is proposed to 

 include in the family are here described as new. Anthaspidella, 

 Zittelella, Streptosolen and Edriospongia are from Cambrian 

 strata, Aulocopium Oswald, and the very closely related Clima- 

 cospongia Hinde, from Silurian, and Syringophyllum from 

 Devonian beds. Besides these, several species now referred to 

 Calathium Billings belong here. That genus contains, we think, 

 at least two structurally distinct types. The first species des- 

 cribed C. formosum Billings resembles Craticularia and may be, 

 as has been suggested by Dr. Zittel, an early representative of 

 the Euretidae. C. canadense Billings or at any rate specimens 

 from the Trenton limestone of Tennessee which we have identi- 

 fied with that species, have the characteristic spicular structure 

 of the Anthaspidellidse. The specimens are silicified and show a 

 few spicules in a fairly satisfactory manner. 



With the exception of Climacospongia, all the genera are 

 characterized by more or less well marked canal systems. Two 

 sets, radial and vertical, prevail in Anthaspidella, Zittelella, 

 Aulocopium and Edriospongia. In Streptosolen the canals in- 

 tertwine to such a degree, that it is difficult to separate the two 

 sets, while in Syringophyllum, the radial system is represented 

 by superficial channels only. In Climacospongia, the larger 

 canals are wanting, but, instead, the spicules are larger, the 

 horizontal bar longer, and, in consequence, the tubular mesh of 

 more ample construction. This genus was described by Dr. 

 Hinde* as a Monactinellid sponge. Specimens obtained from the 

 typical locality clearly demonstrate that he misinterpreted 

 the character of the interior skeleton, and that instead of ver- 

 tically and horizontally arranged simple bi-acerate spicules, they 

 are in reality four-rayed, and arranged in columnar series. 

 These are formed by the intertwining of the vertically, or rather, 



*Cat. of the Poss. Sponges in the Brit. Museum, p. 18, 1883. 



