468 Reviews — Dr. licwff's PalcBOspongiology. 



latter genus as a genuine Lyssakine Hexactinellid, in spite of its 

 peculiar features. Of not infrequent occurrence, both in Silurian 

 and in Carboniferous rocks, are the bundles of spicular rods which 

 anchor the Hexactinellid sponges to the sea-floor ; they have been 

 variously named according to the different opinions held about them ; 

 thus M'Coy and Portlock considered them as annelid tubes, and 

 placed them under Serpula ; subsequently M'Coy placed them in a 

 distinct genus, Pyritonema. For similar spicular bundles in the 

 Carboniferous rocks associated with normal Hexactinellid spicules, 

 von Zittel used the generic term Hyalostelia. It is quite possible 

 that these bundles may have belonged to different species and genera 

 of sponges, and Dr. Eauff proposes to employ M'Coy's name for 

 Silurian, and von Zittel's for Carboniferous specimens. But until it 

 can be proved that the later ones belonged to another genus than the 

 earlier forms, these similar objects cannot rightly be placed under 

 two genera, and only one of these two names can therefore be 

 retained. 



The Ordovician and Silurian Lithistida probably were more 

 numerous and important at this epoch than the Hexactinellida. 

 One of the principal families is that of the Astylospongid^, which, 

 with the Hindiadse, is included by the author in the tribe Eutaxicla- 

 dinidse. In this group the arrangement of the spicules and their 

 mode of attachment to each other to form the skeleton are of a very 

 complicated character; theoretically, according to the scheme of the 

 author, where the rays of the spicule are simple, they are so grouped 

 as to form the outlines of a series of rhombohedra. But as one or 

 more of the rays may be in duplicate, the regularity of the theoretical 

 plan is but seldom apparent in actual sections of these sponges. 

 From an examination of a large number of American and European 

 specimens of the Astylospongidee the author has discovered that the 

 European examples and those from Waldron in Indiana are charac- 

 terized by smaller spicules and a closer skeletal network than exist 

 in the forms from Tennessee and Canada, and though it is acknow- 

 ledged that these latter belong to the same respective genera as the 

 former Dr. Rauff proposes to distinguish them by employing a 

 different generic term ; so that, for instance, the Tennessee specimens 

 are placed under Astylomanon, and the corresponding European 

 forms remain under Astylospongia. We doubt very much the 

 advisability of this proceeding, in view of the author's admission 

 that the Tenesseean and Canadian Astylospongidge belong to the 

 same genera as the European. On the other hand, we quite agree 

 with the author in dividing up the forms hitherto placed under 

 Astylosfongia, retaining this name for the typical A. prcemorsa, 

 Goldfuss, sp., which has a definite cloacal depression, and proposing 

 two new genera, Caryospongia and Carpospovgia, for the specimens, 

 in which there is a different arrangement of the canal system. 



The structure of the skeleton in the genus Hindia, which is made 

 the type of a new family, is stated to be in near relationship to that 

 of the Astylospbngida3. Both the American and European examples 

 are referred to a single species. 



