108 



THE FAK PAST. 



spirifer and productus, are in deep water ; huge nautilus- 

 like cephalopods, nautilus, goniatite, and orthoceratite, in 



L, Sec. 



1, Ditliyrocaris ; 2, Limuloides (Bellinurus) ; 3, Cypris magnified ; 4, Spirorbis 



(Annelid) magnified; 5, Phillipsia (Trilobite) ; 6, Earypterus (Ldothea) 



Scouleri, from Linlithgowshire. 



the open sea ; gasteropods, like euomphalus and pleurotom- 

 aria, on shore ; acephalans, like unio and anodon, in fresh- 

 water and tidal estuaries ; and others, like aviculopecten, 

 mytilus, and mactra, in its shallower bays. The bone- 

 encased fishes of the old red sandstone have now disap- 

 peared, and their place is taken by the more fish-like forms 

 (if we may so express it) of megalichthys, paloeoniscus, am- 

 Uypterus, eurynotus, and platysomus; by gigantic shark-like 

 cestracionts, whose teeth (helodus, poecilodw, psammodus, 

 &c.) and fin-spines (yyracantltus, ctenacanthus, oracanthm, 

 &c.) are alone preserved to us ; and huge sauroid genera 

 (rhizodus, &c.), whose dentition marks an affinity to the 



