324 Revieivs — A. H. Foord's Catalogue of the Cephalopoda. 



certainly siliceous ; the character of another new genus, Camarocladia, 

 is very indefinite. 



A single Stroniatoporoid is placed under Actinostroma ? Trentonense, 

 and its minute structure is stated to resemble that of the Aspidellid 

 sponges ! 



Section vi. treats of Palaeozoic Bryozoa, by E. 0. Ulrich, and 

 forms by far the most important subject in the volume, occupying 

 4U3 pages of text and 49 quarto plates. On this group we can 

 readily recognize that the author is on safer ground than when 

 treating of fossil sponges, for he has thoroughly investigated the 

 microscopic structure of nearly all the American species, and 

 prepared nearly 4000 thin sections for this end. His descriptions 

 and figures furnish an immense addition to our knowledge of the 

 minute structural details of the various forms, and they afford 

 a very striking instance of the advantage to be gained by the 

 systematic microscopic study of all the forms in a single group of 

 organisms. A chapter is devoted to the general and comparative 

 structure of Paleozoic Bryozoa, and the views stated will be 

 generally accepted ; some exceptions, however, might be taken to 

 the assertion that the acanthopores were all originally hollow, 

 though it is acknowledged that their summits generally appear 

 solid at the surface. Allied to the acanthopores are the so-called 

 median-tubules, and the hollow structure of these is equally doubtful. 



As regards the classification of the Palaeozoic Bryozoa, Mr. Ulrich 

 adopts the plan of extreme division, and a great number of new 

 families and genera are introduced on grounds which appear quite 

 insufficient. It is very doubtful if either of the proposed suborders, 

 Trepostomata, Ulrich, and Cryptostomata, Vine, can be logically 

 established ; and numerous objections could be taken to many of the 

 family and generic divisions which have been made. That many of 

 the new genera appear to conflict seriously with those already 

 established is only what may be looked for in a work hailing from 

 the United States, and much of this apparent synonymy could 

 probably be avoided by a franker recognition of the characters of 

 the older types and a less hostile attitude towards the authors of 

 these. In spite of these drawbacks the work of Mr. Ulrich on the 

 American fossil Bryozoa merits the warm appreciation of all palseon- 

 tologists, and affords a safe basis for future students and systematists 

 to build upon. G. J. H. 



III. — Catalogue of the Fossil Cephalopoda in the Beitish 

 Museum (Natukal History), Part IL containing the re- 

 mainder of the Nautiloidea. By Arthur H. Foord, F.G.S. 

 (London, 1891.) Printed by order of the Trustees, and sold by 

 Kegan Paul, Trench, Triibner & Co. 8vo. pp. xxviii. and 408, 

 with a large folding Table and 86 Woodcuts. 



WE gladly welcome Part IL of Mr. Foord's Catalogue of the 

 Fossil Cephalopoda in the British Museum (Natural History). 

 Two years have elapsed since the completion of Part L, containing 

 piart of the suborder Nautiloidea, consisting of the families Ortho- 



