GLOSSARY. 



833 



Distortion of — see I., 5. 

 Index fossil — a fossil which, because 

 of its limited vertical but wide hor- 

 izontal distribution is of value as 

 an index to the age of the stratum 

 where found. For correlation by- 

 means of index fossils, see I., 2. 

 Mode of preservation — see I., 4. 

 Naming of — see I., 5. 

 Types of — see I., 3. 



Fossiila — in corals (some Tetracoralla), 

 the groove in the calyx due to the 

 reduction or abortion of the cardinal 

 septum (see Figs. 84, 83 upper). 



Fox Hills group — upper part of middle 

 Cretacic (Montanan) of Great Plains. 



Franconia sandstone — subdivision of St. 

 Croix formation. 



Frankfort shales — upper Ordovicic of 

 New York, etc. 



Fredericksburg division {Fredericks- 

 bur gian) — middle Comanchic. 



Free cheeks — in trilobites, lateral por- 

 tions of the cephalon separated off 

 by the facial sutures (see Figs. 1542, 

 1557). 



Freemont limestone — upper Ordovicic 

 of Colorado. 



Freeport formation — upper division of 

 the Alleghenian (middle Coal Meas- 

 ures) of Ohio, Pennsylvania, etc. 



Frond — the body formed by the union 

 of stem and leaf among ferns, lichens 

 and palms. Also the leaf-like expan- 

 sion of an entire graptolite or bryo- 

 zoan colony. 



Fucoid — a seaweed, particularly of the 

 type similar to the modern Fucus or 

 rockweed. 



Functional — pertaining to the appro- 

 priate action of any special organ or 

 part of an animal or vegetable organ- 

 ism. 



Funiculus — a small cord (see II., 387). 



Furcate — branching like a fork. 



Furrow — for use in trilobites, see II., 

 251, and Fig. 1542 ; in insects, see II., 

 424. 

 Dorsal furrow — see dorsal. 



53 



Lateral furrows — in trilobites, see 

 Fig. 1542. 



Occipital furrows — see occipital. 

 Fusiform — spindle-shaped (see Fig. 18). 

 Fusoid — spindle-shaped. 



Galeate — with a helmet-like covering. 

 Galena limestone — upper Ordovicic 



(Trenton) of central North America. 

 Gallatin limestone — middle Cambric of 



Yellowstone region. 

 Garnett limestone — Carbonic of Kansas. 

 Garrison formation — lower Permic of 



Kansas. 

 Gasconade limestone — upper Cambric 



of the Ozarks. 

 Gaspe limestone — Helderbergian (lower 



Devonic) of eastern Canada. 

 Gaspe sandstone — middle and upper De- 

 vonic of eastern Canada. 

 Gastric — pertaining to the stomach. 

 Gatun formation — middle Eocenic of 



the Isthmus of Panama. 

 Gay Head beds — Miocenic of Atlantic 



coast. 

 Gemmation — the formation of young by 



budding, as in some corals. 

 Genal — pertaining to the cheeks. 



Genal angles — posterior lateral an- 

 gles of the free cheeks of trilobites. 



Genal spines — posterior prolongations 

 or spines of the free cheeks of 

 trilobites. 

 Generic name — see genus. 

 Genesee shale — upper Devonic of New 



York, etc. 

 Genetic — pertaining to origin. 



Genetic affinity — relationship by di- 

 rect descent. 

 Geniculate — bent abruptly at an angle. 



In brachiopods, referring to those 



shells with the front portion bent 



abruptly, almost at a right angle (see 



Fig. 273, b). 

 Genital plates — in echinoids, the upper 



of the two circles of plates in the 



apical system ; they are situated in- 



terradially. Called also basal plates 



(see Fig. 1935, g). 

 Genotype — see type. 



