378 Reviews — Dr. Gregory's Jurassic Bryozoa. 



I have only to add that this work has been done in the Geological 

 Eesearch Laboratory of the Eoyal College of Science ; and to express 

 my thanks to Professor Judd for the assistance and many valuable 

 suggestions that he has given me. 



EEVIE W S. 



I. — Catalogue of the Jurassic Bryozoa in the British Museum 



(Natural History). By J. W. Gregory, D.Sc, F.G.S., F.Z.S. 



(1 vol., 8vo; pp. 240, 11 Plates.) London : l.s96. Printed by 



order of the Trustees. Dulau & Co., 37, Soho Square, W. 



Price 10s. 



rpHIS volume is the first of a series, which, when completed, will 



S form a Catalogue of the fossil Bryozoa in the British Museum. 



Dr. Gregory explains that he has begun with the description of 



the Jurassic Bryozoa, because "it is among the Jurassic deposits that 



we must seek the ancestors of existing types," and because the 



primary lines of divergence are hei - e well marked, and not obscured 



by secondary variations of later periods. Further, it was necessary to 



work out the Jurassic fauna befoi'e attempting the Cretaceous, which, 



of all British Bryozoan faunas, is most in need of further investigation. 



Of the seventy-nine species here described, sixty-nine are included 



in the Cyclostomata, eight in the Trepostomata, and two in the 



Cheilostomata. The Cryptostomata, which occur so abundantby in 



Palaeozoic times, and^which are usually assumed " to take the place 



of" the Cheilostomata, have not been found in the Jurassic strata. 



The Trepostomata, which likewise prevailed in the Palaeozoic strata, 



form a dwindling remnant in the Jurassic. The Cheilostomata, which 



preponderate in later times, have not yet risen into importance. 



The classification of the orders is based on zocecial l characters. 

 The Trepostomata are characterized by the change in the nature of 

 the distal as compared with the proximal parts of the zooecial tubes, by 

 the presence of mesopores, diaphragms, acanthopores, etc. The order 

 Cyclostomata, which includes 87 per cent, of the species here catalogued, 

 is separated from the others rather by its negative characters. Dr. 

 Gregory divides this order into four suborders : 1, Articulata (including 

 Crisiidee) ; 2, Tubulata ; 3, Dactylethrata ; 4, Cancellata (including 

 Discoporellidae). The first and fourth do not occur in the Jurassic 

 deposits. Accordingly, the Jurassic Cyclostomata fall into two 

 groups — the Tubulata (including 65 species), in which the zocecia 

 are monomorphic ; and the Dactylethrata (including 4 species), in 

 which aborted closed zocecia or " dactylethra? " are present in addition 

 to the normal open ones. 



It has always been a difficult matter to satisfactorily classify the 

 forms (recent as well as fossil) included in the Tubulata. The 

 zocecial characters are of no use in the splitting up of this suborder 



1 Zoce-cium, the individual tube or cell containing in life the polypide ; zoarium, the 

 colony of tubes or cells. 



