444 GEOLOGICAL SURVEY OF THE TERRITORIES. 
Discarding the Phyllopod forms, we here 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 Nebalia,! Claus 
thus refers to the 
paleozoic forms: 
“Tt 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 instrue- 
tive error, to which 
the consideration of 
Nebalia gave occa- 
sion, will lead us to 
exercise greater cau- 
tion in the interpre- 
tation of such incom- 
plete and imperfectly 
-known remains. 
“In Ceratiocaris 
Salter we have a 
great Nebalia-like 
carapace by which a 
Fig. 69.—1. Hymenocaris (Lingula Flags) ; 2. Peltocaris (Lower Silu- series of free Peer 
rian); 3. Ceratiocaris (Upper Silurian); 4. Dictyocaris (Devonian) ; ments were covered, 
5. Dithyrocaris (Carboniferous); (6. Argus); 7. Nebalia (Recent). 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 antennee 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 Dictyocarts Salt. 
and Dithyrocaris of Scouler to the other Silurian fossils regarded as 
Phyllopods (Hymenocaris, Peltocaris) will remain problematical until 
| 
/ 
Recent. 
Carboniferous. 
Upper Silurian. Devonian. 
Lower 
Silurian. 
Lingula 
Flags 
1Siebold u. Kélliker’s Zeitschrift. xxii, 1872, p. 329. 
