76 



Guide to the Invertebrata. 



GALLERY the Trilobites share with Apus), entirely confirms this conclusion. 

 East Side P^^obably two thousand species and over one hundred genera of 

 "Wall-cases Trilobites are known from Palaeozoic rocks. They first appear 

 13 & 14, in the Lower Cambrian, attaia their maximum development in 

 cases ' ^^^ Silurian ; about four genera continue on into the Carboniferous 

 80-82. period, after which they entirely disappear. 



Fig. 128. — Calymene Blu- 

 menbachii, Brong. Upper 

 Silurian: Dudley. 



Fig. 129. — Acidaspis mira., 

 Beyr. Upper Silurian: 

 Dudley. 



Fig. 130. — Staurocepkalus 

 Murchisoni, Barr. Upper 

 Silurian: Dudley. 



Fig. 131. — Homalomtus 

 delphinocephalus, Green, 

 Upper Silurian : Dudley. 



Fig. 132. — Brontem 

 Jlabellifer, Goldf. 

 Devonian: Newton, 

 Devon. 



Fig. 133. — Br achy me- 

 topus Ouralicus,V orH. 

 Carboniferous Lime- 

 stone : Settle, York- 

 shire. 



