1XX PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [May 1 895. 



And now — if your patience be not already exhausted by my too- 

 lengthy preamble — I will beg your indulgence whilst I endeavour 

 to briefly treat of 



Some Points in the Liee-history oe the Crustacea, in 

 Early Paleozoic Times. 



Of the various groups of the Invertebrata whose ancestry extends 

 into Palaeozoic times, none possess a greater interest for the geologist 

 than the Crustacea, whose existence is proved as far back as the 

 Lower Cambrian rocks ; while their near allies, the Arachnida, 

 have been met with in strata as old as the Silurian. 



My earliest papers on the Eurtpterlda appeared in 1863 and 1864, 

 and an account of Stylonurus and Hemiaspis was communicated to 

 this Society in 1865, just 30 years ago. In that year (1865) I had 

 the pleasure, with my friend and fellow- worker, the late J. W. Salter, 

 F.Gr.S., of publishing a ' Chart of Fossil Crustacea,' * in which an 

 attempt was made to show the evolution in time of the various forms 

 belonging to this class, graphically depicted on an engraved folding- 

 sheet, with explanatory text. "We pointed out that the main 

 development of the Crustacea in Palaeozoic times consisted of the 

 great groups of the Trilobita, the Etjrypterida, the Xiphosura, 

 the Phyllopoda, and the Ostracoda. 



The faint beginnings of other great groups were also indicated, 

 such as the macrouran-decapods represented by Anthrapalcemon 

 and other forms in the Coal Measures ; the stomatopods by Pygo- 

 cejaihalus Cooperi, the amphipods by Gampsonyx, both in the Coal 

 Measures ; and by Prosoponiscus in the Permian. 



Lastly, the Cirripedia, by the anomalous form made known in 

 1865, 2 under the name of Turrileptas, from the Wenlock Limestone. 



In November 1866, I laid before this Society the evidence upon 

 which I based my arrangement of the Pterygoti and Limuli in one 

 order, for which I adopted Dana's very appropriate name of Mero- 

 stomata (or ' thigh-mouthed ' animals) — expanded to include all 

 those ancient crustaceans comprehended in the two suborders of 

 Eurypterida and Xiphosura and forming two groups of long-bodied 

 and short-bodied forms, quite parallel to the Brachyoura and 

 Macroura in the Decapoda ; even the intermediate forms — corre- 

 sponding to the Anomoura — being paralleled by the Hemiaspidse 

 (Hemiasjpis, Pseudoniscus, etc.). This group formed the subject of 



1 Engraved and published by J. W. Lowry, and sold by J. Tennant, Strand. 



2 Quart. Journ. Greol. Soc. vol. xxi. pi. xiv. p. 486. 



