Reviews — Geological Surrey of Illinois. 323 



off rootlets or cirrhi in all directions, from which the authors 

 conclude that these and other PalEeocrinoids probably lived a semi- 

 free existence, like recent forms of Pentacrinns, either anchored by 

 the cirrhi to the soft oozy sea-bottom, or at intervals attached to 

 foreign bodies. The new species belong to the following genera : 

 Actinocrinus, Megistocrinus, Dorycrinus, Rhodocrinus, Plaiycrinus, 

 Dichocrinus, Graphiocrinus, Scnphiocrinus, and Taxocrinus. A speci- 

 men of a new Blastoid, OropJiocrinus /usiformis, retains a portion of 

 the stem and also the pinnules. 



In sections iii. iv. and v. Mr. E. 0. Ulrich (in part nominally 

 associated with Mr. 0. Everett) ti'eats of American Palaeozoic Sponges. 

 The author's study of this group of fossils is evidently limited and 

 imperfect, shown more particularly when he ventures to express 

 opinions of his own as distinct from those procured from the 

 writings of and correspondence with experienced authorities. Thus, 

 for example, he believes that there are homological affinities between 

 some of the new Silurian lithistid sponges described and the 

 Stromatoporoid genus Actinostroma ! It is generally acknowledged 

 that the correct determination of fossil sponges is beset with special 

 difficulties owing to mineral changes which they have undergone, 

 and those which Mr. Ulrich has attempted to describe are no 

 exceptions to the rule. This fact will, perhaps, account for the 

 extraordinary type of spicule which is figured as characteristic of 

 a proposed new family, the Aspidellidas (p. 224, fig. 6), in which, 

 four smooth simple rays are thrown off in pairs from the ends of 

 what is styled a profoundly elongated node or horizontal central bar ! 



Of Devonian and Carboniferous forms, the author describes four 

 new genera : Hystriospongia, a tetractinellid ; Batospongia, either a 

 lithistid or a calcisponge ; Belemnospongia, a monactinellid, but which, 

 if correctly delineated as having acerate spicules connected by short 

 transverse processes, must be quite distinct from this sub-order, and 

 Syringelasma, a lithistid. At the lower horizon of the Trenton 

 limestone, at a single locality in Illinois, a considerable number of 

 fossil sponges have been obtained, which retain their outer forms 

 and canal structure, but their original siliceous skeletons have been 

 replaced by calcite. These sponges have been arranged in several 

 new genera, and placed as a distinct lithistid family of the Aspidellidae 

 on the ground that the form of their spicules differs from that of 

 any previously described sponge. From an examination of some 

 of these forms, we believe their spicular structure is closel}^ similar 

 to that of Astylospongia and that they can be included in the 

 Anomocladina family. The two principal genera are Zittelella and 

 Anthaspidella, which apparently difi'er only in the fact that the 

 former is simple and the latter compound. The former genus, 

 moreover, seems to be synonymous with the previously described 

 Steliella,^ Hinde, which has been overlooked by the author. Another 

 new genus, Edriospongia, seems to be based on a portion of a 

 specimen of Aspidella. Strotospongia and Dystactospongia are 

 included with Calcisponges ; but the former of these is almost 

 1 Canadiau Record of Science, Jnly, 1859, p. 395. 



