A MONOGRAPH 



ON THE 



BRITISH PALEOZOIC PHYLLOPODA. 



(PHYLLOCARIDA, Packard.) 



INTEODUCTION. 



Fossil remains referable only to organisms related to such Phyllopodous animals 

 as Nebalia, Apus, and Estheria have been met with in many of the Geological 

 Formations. Dr. Scouler, in 1835, was the first to treat of one of these fossils, 

 namely, Argas (afterwards Dithyrocaris), having some alUance to Apus. Professor 

 M'Coy, in 1848, and Mr. J. W. Salter, in 1853, described remains of some more or 

 less Nebalia-]ike genera {Geratiocaris and Hymenocaris). Subsequently numerous 

 other forms, variously related to the two above-mentioned Crustaceans, have been 

 described and figured by paleeontologists at home and abroad. The history of the 

 fossil EsthericB has already been given in a Monograph published by the PaljEonto- 

 graphical Society in 1862. 



A general view of the generic characters and geological distribution of these 

 fossil Phyllopoda is offered in the annexed Table. We may mention that Dr. A. S. 

 Packard, junr., in 1879 and 1883, leaving Estheria among the true Phyllopoda 

 (Branchiopoda), has referred all the other fossil forms in the accompanying list, 

 with which he was acquainted, together with Nebalia, to a separate group, the 

 Phyllocarida which we now propose to adopt. 



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