676 



HISTORICAL GEOLOGY. 



the leaves and stems of submerged plants. The specimen figured is from 

 Nova Scotia (Dawson). They are reported also from the Pennsylvania 

 Coal-measures. 



1081-1085. 



1081. 



1082. 



1084 a. 



1084. 



PtTLMONATE GASTROPODS. — Fig. 1081, Pupa vetusta (x|); 1082, P. Vermilionensis ; 1083, Dawsonella Meeki. 

 Natttiloid Cephalopods. —Figs. 1084, a, Phacoceras Dumbli (x ^); 1085, Temnochilus crassum. Pig. 1081, 

 Dawson ; 1082, 1083, F. H. Bradley ; 1084, 1085, Hyatt, '90. 



1086, 



I 



i 



5. Limuloids. — Species of the group of Eurypterids were common. Speci- 

 mens of one of them, four to ten inches long, the Eurypterus Mansfieldi of 



C. E. Hall, are found in the shale below the Darlington cannel 

 coal, near Cannelton, Pa., laid out among Ferns and Calamites, 

 as represented in Fig. 1087. The species probably lived in fresh- 

 water marshes and ponds. In addition, the modern tribe of 

 Limulids had its species : one from Morris, 111., is represented in 

 Fig. 1088. Another species, Cyclus Americanus of Packard, had 

 an even, nearly circular outline, without a telson, and closely 

 resembled an embryonic Limulus. 



6. Crustaceans. — Trilobites were rare, and of the genera PhiUipsia, Grif- 

 fithides and Bracliymetopus. 



Under Crustaceans there were also various species of modern aspect, 

 represented in Figs. 1089 to 1091, the latter two, if not all three, true 

 Decapods. The Myriapods were mostly related to the inferior lulus tribe 

 — nearly cylindrical species (as Figs. 1092, 1093) having often two pairs 

 of, legs to a body segment. But in one species, the Palmocampa anthrax of 

 Meek and Worthen, from Illinois, the body had but 10 segments ; and on its 



Spirorbis 

 carbonarius 



