444 



GEOLOGICAL SUEVEY OF THE TERRITORIES. 



Discarding the Phyllopod forms, we liere reproduce Salter's figures 

 and geological succession, which has been confirmed by the discoveries 



of Barrande and H. 

 Woodward. Salter's 

 figure of Nebalia is, 

 however, replaced by 

 an original one. 



In his article on 

 the structure and 

 systematic position 

 of Kebalia,^ Glaus 

 thus refers to the 

 paleozoic forms: 



"It is generally 

 considered that the 

 oldest paleozoic crus- 

 tacean remains 

 whose shells and 

 form of the body 

 partly resemble 

 Apus, and partly 

 show a great simi- 

 larity to Nebalia, for 

 this reason are con- 

 sidered to be Phyl- 

 lopods, though we 

 are without any in- 

 formation as to the 

 nature of the limbs. 

 But now the instruc- 

 live error, to which 

 the consideration of 

 Nebalia gave occa- 

 sion, will lead us to 

 exercise greater cau- 

 tion in the interi)re- 

 tation of such incom- 

 plete and imperfectly 

 known remains. 



"In Ceratiocaris 

 Salter we have a 

 great Nebalia-like 

 carapace by which a 

 series of free seg- 

 ments were covered, 

 and moreover a long 

 well-separated lancet-formed rostrum. On the other hand, the form of 

 the abdomen, with the powerfully developed telson beset with lateral 

 spines, indicates a different form, which also finds expression in the 

 appendages of C. papilio Salt, figured as anteunte or thoracic limbs. If 

 these representations indicate true limbs, then they remind us most of 

 the larval limbs of Decapods. So also the position of Dictyocaris Salt, 

 and Bithyrocaris of Scouler to the other Silurian fossils regarded as 

 Phyllopods (Hymenocaris, Peltocaris) will remain problematical until 



Fie 

 rian) 



69. — 1. Hymenocaris (Linsula Flags) ; 2. Peltocaris (Lower Siln- 

 3. Ceratiocaris (Upper Silurian) ; 4. Dictyocaris (Devonian) ; 



5. Dithyrocaris (Carboniferous) ; (6. Argus); 7. Nebalia (Recent). 



' Siebold u. Kolliker's Zeitsclirift. xxii, 1872, p. 329. 



