282 Reviews — P. Pocfa's Chalk Sponges of Bohemia. 



have been already made known in the works of Reuss, Geinitz and 

 Eomer; but this is the first attempt to ascertain sj'stematically their 

 minute structure. It is rather unfortunate, however, that the author 

 couhl not obtain access to the original types of Reuss's species, 

 described in the " Versteinerungen der bohmischen Kreideforma- 

 tion," and could therefore only rel}' on the descriptions and figures 

 for comparison ; as, however, the sponges described by the author, 

 now forming part of the collection in the Royal Bohemian Museum 

 at Prague, were obtained for the most par tfrom the same localities as 

 Reuss's types, there is less liability to mistake in identifying his species. 



The lowest strata of the Cretaceous series of Bohemia in which 

 fossil sponges are found — the Korytzaner beds — are referred to 

 Cenomanian age. They consist mainly of calcareous and marly 

 materials deposited in fissures in gneiss. From these beds by far 

 the larger majority of the sponges have been obtained, as from the 

 accompanying tables of species it appears that out of a total number 

 of 99 species of Lithistids and Hexactinellids, 77 are present in 

 them. In the overlying Weissenberger and Malnitzer strata, of 

 Turonian age, only 15 species have been observed ; and from the 

 succeeding Senonian strata, divided respectively into Iser, Teplitzer, 

 Priesener, and Chlomek-schichten, 22 species are recorded. 



As regards their state of preservation, the Bohemian fossil sponges 

 present nearly similar conditions to those of this country. In some 

 examples the siliceous skeleton is but little altered by fossilization, 

 so that by treatment with dilute acid the sponges may be nearly 

 entirely freed from the matrix, but in the majority of instances the 

 original structures have been altered to a greater or lesser degree, 

 and the delicate siliceous spicular mesh has been masked by accre- 

 tions of silica or replaced by crj^stalline calcite, iron pyrites or iron 

 peroxide. The author notices as a peculiar fact that even in the 

 same locality the condition of the sponges is very variable, and not 

 infrequently, examples with perfectly preserved skeletons occur in. 

 the same beds with others in which the skeletal structure has been 

 destroyed or replaced. 



The first part of the work treats of the Hexactinellids, of which 

 there are 31 species ranged under the following genera : Craticularia, 

 Zeptophi-agma, Pleurostoma, Guettnrdia, PetaJope, nov. gen., Synaulia, 

 nov. gen., Lopanelln, nov. gen., Botroclonium, nov. gen., Stauronema, 

 Ventriculites, Plocoscyphia, Tremabolites, Cyrtobolia, nov. gen., Diplo- 

 dictyon, and Ccelopiychinm. No fewer than 21 species are regarded 

 as new. The Lithistids, desci'ibed in the second part, are placed 

 under 46 species ; of which 21 are new forms, though the author 

 has onlj' constituted a single new genus, Paropsites. The greater 

 number of forms belong to the Rhizomorina family, and the following 

 genera are represented, Bolidium, AstrohoUa, Chonella, Seliscothon, 

 Chenendopora, Verruculina, Stichophyma, Coelocorypha, and Scytalia. 

 A single species each of Doryderma and Isoraphinia belong to the 

 family of the Megamorina. The Tetracladina family are represented 

 by the genera Phymatella, Siphonia, Jerea, Polyjerea, Astrocladia, 

 ThecGsiphonia, Bacodiscula, Paropsites, Bagadinia, and Plinthosella. 



