Reviews — Nicholson and Lydekker's Palaeontology. 85 



Fossil Caloisponges are now known to have a wide distribution 

 and to be abundant in Jurassic strata; their very existence as fossils 

 was denied up to a very recent period ; on the other hand, forms 

 formerly referred here, such as the Stroniatoporoids, are now placed 

 in the Coelenterata. 



The Archaeocyathina?, from the Cambrian strata of Europe and 

 America, are regarded as of doubtful affinities ; but recent researches 

 show that they possess a considerable resemblance to Madreporarian 

 Corals. The real nature of Pasceolus, Cyclocrinus, and Nidulites is 

 still uncertain. 



Coming now to the Hydrozoa, there are good figures of Hydrac- 

 tinia and Parlceria, and also of the peculiar genera Mitcheldeania and 

 Solenopora, which form an important part of many Palaeozoic lime- 

 stones. Oldhamia is still retained with the Hydroida, though its 

 nature is open to great doubt. 



Passing over the Graptolites, of which several new figures are 

 given, we reach the Hydrocorallines and Stroniatoporoids, and, as 

 might be expected from the author's researches in tins latter group, 

 their structural features are clearly described and illustrated. Tbey 

 are considered as forming a special and now unrepresented group of 

 Hydrozoa, some forms having relations to the recent Hydractinia, 

 and others to Hydrocorallines like Millepora. 



Considering the importance as fossils of the Actinozoa or Corals, 

 we are glad to note the greatly increased space devoted to them in 

 this edition, so that their general features, different modes of growth 

 and increase, and more particularly their minute structural characters, 

 are treated fully, and well shown in the elaborate figures, most of 

 which are original. It is acknowledged that the classification of 

 this group is in a transitional state, and that the position of the 

 Rugosa as a separate order cannot be maintained ; but it is still kept 

 distinct, and with the Aporosa, Fungida and Perforata, form the 

 primary sections of the Madreporaria. There can be little doubt 

 however, that many, if not most of the Rugosa will enter into the 

 division of the Aporosa. One of the principal grounds of distinction 

 was based on the supposed tetrameral development of the septa, but 

 the importance of this has been overestimated, and we find here that 

 the Coral, Stauria astrceiformis,\n which this tetrameral arrangement 

 is most conspicuously shown, has been removed from the Rugosa 

 and placed with the Astraeida in the Aporosa. 



To the section of the Madreporaria Perforata, previously regarded 

 as almost exclusively Mesozoic and Tertiary, considerable additions 

 have been lately made from the older rocks. Thus we have the 

 genus Calostylis from the Wenlock, Cleistopora from the Devonian 

 and Palceacis from the Carboniferous; whilst the great family of the 

 Favositidae, formerly in the now obsolete group of the Tabulata, 

 also finds its place in this division. Though somewhat more 

 aberrant in their mode of growth, the Syringoporida? and the 

 Thecidae are likewise included in the Perforata. 



The Palaeozoic families of the Heliolitidae and the Halysitida? 

 are placed with Alcyonarian Corals on account of their presumed 



