GLOSSARY. 385 
DicyNopDontTIA (Gr. dis, twice; kuon, dog; odous, tooth). An extinct order of 
Reptiles. 
Dee eaes (Gr. didumos, twin ; grapho, I write). A genus of Graptolites. 
DIMORPHODON (Gr. dis, twice; morphé, shape; odous, tooth). A genus of 
Pterosaurian Reptiles. 
DrnicatHys (Gr. deinos, terrible ; ichthus, fish). An extinct genus of Fishes. 
DrnocerRas (Gr. deinos, terrible ; keras, horn). An extinct genus of Mammals. 
DINopHIs (Gr. deinos, terrible ; ophis, snake), An extinct genus of Snakes. 
DrvornIs (Gr. deinos, terrible; ornis, bird). An extinct genus of Birds. 
DreLoGRraPtus (Gr. diplos, double ; grapho, I write). A genus of Graptolites. 
Drpnot (Gr. dis, twice ; pnoé, breath). An order of Fishes, comprising the 
Mud-tishes, so called in allusion to their double mode of respiration. 
Diproropon (Gr. dis, twice ; protos, first; odous, tooth). A genus of extinct 
Marsupials. 
DipTeRA (Gr. dis, twice; pteron, wing). An order of Insects characterised 
by the possession of two wings. 
Discorp (Gr. diskos, a quoit; eidos, form). Shaped like a round plate or 
quoit. 
DOLoMITE (named after M. Dolomieu). Magnesian limestone. 
Dorsat (Lat. dorsum, the back). Connected with or placed upon the back. 
DROMATHERIUM (Gr. dromazos, nimble ; thérion, beast). A genus of Triassic 
Mammals. 
DryopiTHEcus (Gr. drus, an oak; pithekos, an ape). An extinct genus of 
Monkeys. 
ECHINODERMATA (Gr. echinos ; and derma, skin). A class of animals com- 
prising the Sea-urchins, Star-fishes, and others, most of which have spiny 
skins. 
ECHINOIDEA (Gr. echinos ; and erdos, form). An order of Echinodermata, com- 
prising the Sea-urchins. 
EDENTATA (Lat. e, without ; dens, tooth). An order of Mammalia often called 
Bruta. 
EDENTULOUS. Toothless, without any dental apparatus. Applied to the 
mouth of any animal, or to the hinge of the Bivalve Molluscs. 
ELASMOBRANCHII (Gr. elasma, a plate; bragchia, gill). An order of Fishes, 
including the Sharks and Rays. 
ENALIOSAURIA (Gr, enalios, marine ; saura, lizard). Sometimes employed as 
a common term to designate the extinct Reptilian orders of the Ichthyosauria 
and Plesiosauria. 
EocENE (Gr. eos, dawn; kainos, new or recent). The lowest division of the 
Tertiary rocks, in which species of existing shells are to a small extent 
represented. 
EopHyTon (Gr. eos, dawn; phuton, a plant). A genus of Cambrian fossils, 
supposed to be of a vegetable nature. 
E0ZOON (Gr. eos, dawn; zodn, animal). A genus of chambered calcareous or- 
ganisms found in the Laurentian and Huronian formations. 
EQUILATERAL (Lat. equus, equal; latus, side). Having its sides equal. Usu- 
ally applied to the shells of the Brachiopoda. When applied to the spiral 
shells of the Foraminifera, it means that all the convolutions of the shell lie 
in the same plane. 
EQUISETACE# (Lat. .equus, horse ; seta, bristle). A group of Cryptogamous 
plants, commonly known as ‘‘ Horse-tails.” 
EQUIVALVE (Lat. equus, equal ; valve, folding-doors). Applied to shells which 
are composed of two equal pieces or valves. 
ERRANTIA (Lat. erro, I wander). An order of Annelida, often called Nereidea, 
distinguished by their great locomotive powers. 
EUOMPHALUS (Gr. eu, well; omphalos, navel). An extinct genus of Univalve 
Molluscs. 
EuRYPTERIDA (Gr. euvrus, broad ; pteron, wing). An extinct sub-order of Crus- 
- taced. 
Exoeyra (Gr. exo, outside; gwros, circle). An extinct genus of Oysters. 
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