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THE AMERICAN NATURALIST. [Vol. XXXVI L 



In a foot note Murchison adds : " Mr. Miller has requested 

 his readers to compare the head of Asaplius (now Phacops) 

 caudatus, a well-known Silurian trilobite, with that of C. lyellii, 

 to illustrate how the two orders of Crustaceans and Fishes seem 

 here to meet, — in the view of persons who have not mastered 

 the subject." 



F^ichwald says ('54, p. 105): "It is very remarkable that this 

 colossal crab (Pterygotus) formerly regarded by L. Agassiz as a 



fish occurs in the dolomitic chalk of Rootzikiill in Oesel, 



together with another genus, Thyestes, standing between Crabs 

 and Fishes and resembling Bunodes and Cephalaspis." 



Hugh Miller, the discoverer of Pterichthys, says {Old Red 

 Sandstone, p. 50), in comparing a trilobite with Cephalaspis 

 "The fish and the Crustacean are wonderfully alike.".... 

 " They exhibit the points, .... at which the plated fish is linked 

 to the shelled Crustacean." 



Sir Roderick Murchison, when first shown specimens of 

 Pterichthys wrote regarding them that, " if not fishes, they more 

 clearly approach to crustaceans than to any other class." 

 Again, " They (Cephalaspis and Pterichthys) form the connect- 



in^doubt as to whether Pterichthys was a fislfor a crustacean. 



The following quotation illustrates the attitude of modern 

 paleontologists toward the ostracoderms. A. S. Woodward, 

 whose opinion on this subject is entitled to the greatest respect, 

 in his recent text -book of Paleontology ('98, p. 5) states that 

 " Nearly all the genera (of the ( )stracodermi) mimic in a curi- 

 ous manner the contemporaneous Eurypterids " ; and on p. 

 24 of the Introduction, that " The oldest Ostracoderms .... 



