8 Prof. Nicholson — Progress in Palceontology. 



investigations of paleeontologists themselves, have greatly modified 

 our conceptions of the old order " Tabulata." and, in the opinion of 

 some, have fairly abolished this division. "With the removal of 

 Millepora to the Hydrozoa, and of Heliopora and its allies to the 

 Alcyonaria, along with the discovery by Yerrill that Pocillopora is a 

 true Ferforate Coral, the group of the Tabulate Corals has under- 

 gone serious mutilation, and it remains for future researches to show 

 whether it can be retained as a separate division of the Zoantharia. 

 In the meanwhile, it may be best retained for various ancient types 

 of Corals which cannot at present be definitely referred to other 

 sections (Favosites? Ghcetetes? Syringopora, Halysites, etc.). 



The proposal of the late Prof. Louis Agassiz, adopted by many 

 American paleontologists and zoologists, to remove the whole of the 

 great group of the Eugose Corals to the Hydrozoa, is not, in my 

 opinion, supported by sufficient evidence, and is contradicted by 

 many considerations of great weight. Judging both from the 

 structure of the extinct forms, and also from that of the aberrant 

 living genus Edioardsia, it seems best in the meanwhile to regai'd 

 the Bitgosa as standing between the two great sections of the 

 Zoantharian and the Alcyonarian Actinozoa. 



Amongst the Echinoderms, one of the most noticeable points of 

 progress is the light which has been thrown upon the structure of 

 the strange and ancient group of the Ferischoechinidce by the dis- 

 covery of the living flexible Echinoids, Asthenosoma or Calveria, 

 and Phormosoma. Not only do we now know that old forms of 

 these singular types existed in the Secondary period (the Echino- 

 tlmria of the Cretaceous) ; but we further know that some of the 

 still older Pal£eozoic PerischoecTiinidce were furnished with imbri- 

 cated plates, this structure communicating to the test a considerable 

 amount of flexibility. Another point of interest as concerning this 

 order is the establishment (through the labours of Wyville Thomson, 

 Kofe, Billings, Wachsmuth, etc.) of the fact that the mouth of the 

 Palseocrinoids was concealed beneath the perisome, entirely hidden 

 from external inspection, and that the so-called "proboscis" was 

 truly an excrementitious aperture. 



The remaining groups of Invertebrates I must pass over with very 

 scant notice, though our knowledge of their fossil representatives has 

 been immensely increased in various directions in late years, and in 

 some cases very interesting discoveries have been brought to light. 

 Among the Annidosa, the most noticeable point is the gradual exten- 

 sion of our knowledge concerning the air-breathing Arthropods — the 

 AracTinida, Myriapoda, and Insecta — of the Carboniferous period. 

 To this, as usual, that indefatigable investigator, Mr. Henry Wood- 

 ward, has largely contributed. Among the lower Mollusca, con- 

 siderable additions have been made to our knowledge. Many new 

 forms of Polyzoa have been described, and Prof. Young and Mr. 

 John Young have shown us, in their investigation of Rliahdomeson, 

 how much light may be thrown upon the structure of these minute 

 and puzzling fossils by -the method of examination by means of 

 thin sections. Mr. E. Etheridge, jun., has made the curious dis- 



