796 



GLOSSARY. 



DEINOCERATA or DINOCERATA (Gr. deinos, terrible ; Iceras, horn). An extinct 



order of Tertiary Mammals. 

 DEINOSAURIA or DINOSAURIA (Gr. deinos, terrible ; saura, lizard). An extinct 



order of Eeptiles. 

 DENDRIFORM, DENDRITIC, DENDROID (Gr. dendron, a tree). Branched like a 



tree, arborescent. 



DENTIROSTRES (Lat. dens, a tooth ; rostrum, a beak). The group of Perching 

 Birds in which the upper mandible of the beak has its lower margin toothed. 

 DERMA or DERMIS. (See Cutis.) 



DERMAL (Gr. derma, skin). Belonging to the integument. 

 DERMOSCLERITES (Gr. derma, skin ; skleros, hard). Masses of spicules which 



occur in the tissues of some of the Alcyonaria (Actinozoa). 

 DESM.IDI2E. Minute fresh- water plants, of a green colour, without a siliceous 



epidermis. 

 DEUTEROZOOIDS (Gr. deuteros, second ; zoon, animal ; eidos, form). The zooids 



which are produced by gemmation from zooids. 



DEXTRAL (Lat. dextra, the right hand). Eight-handed ; applied to the direc- 

 tion of the spiral in the greater number of univalve shells. 

 DIAPHRAGM (Gr. diaphragma, a partition). The " midriff," or the muscle 



which in Mammalia forms a partition between the cavities of the thorax 



and abdomen. 

 DIASTEMA (Gr. diet, apart ; histemi, I place). A gap or interval, especially 



between teeth. 

 DIASTOLE (Gr. diastello, I separate or expand). The expansion of a contractile 



cavity such as the heart, which follows its contraction or " systole*." 

 DIATOMACE^E (Gr. diatemno, I sever). An order of minute plants, which are 



provided with siliceous envelopes. 

 DIBRANCHIATA (Gr. dis, twice ; Iragchia, gill). The order of Cephalopoda 



(comprising the Cuttle-fishes, &c.) in which only two gills are present. 

 DICYNODONTIA (Gr. dis, twice ; kuon, dog ; odous, tooth). An extinct order 



of Reptiles. 

 DIDELPHIA (Gr. dis, twice ; delphus, womb). The subdivision of Mammals 



comprising the Marsupials. 

 DIGIT (Lat. digitus, a finger). A finger or toe. 



DIGITIGRADA (Lat. digitus ; gradior, I walk). A subdivision of the Carnivora. 

 DIGITIGRADE. Walking upon the tips of the toes, and not upon the soles of 



the feet. 

 DIMEROSOMATA (Gr. dis ; meros, part; soma, body). An order of Arachnida, 



comprising the true Spiders, so called from the marked division of the body 



into two regions, the cephalothorax and abdomen. The name Araneida is 



often employed for the order. 

 DIM Y ART (Gr. dis, twice ; muon, muscle). Applied to those bivalve Molluscs 



(Lamellibranchiata) in which the shell is closed by two adductor muscles. 

 DICECIOUS (Gr. dis, twice ; oikos, house). Having the sexes distinct ; applied" 



to species which consist of male and female individuals. 

 DIPHY DONT (Gr. dis, twice ; phuo, I generate ; odous, tooth). Applied to 



those Mammals which have two sets of teeth. 

 .DIPHYOZOOIDS. Detached reproductive portions of adult Calycophoridce, an 



order of oceanic Hydrozoa. 

 DIPNOI (Gr. dis, twice ; pnoe, breath). The order of fishes represented by the 



Lepidosiren. 

 DIPTERA (Gr. dis, twice ; pteron, wing). An order of insects characterised by 



the possession of tAvo wings. 



DISCOID (Gr. diskos, a quoit ; eidos, form). Shaped like a round plate or quoit. 

 DISCOPHORA (Gr. diskos, a quoit ; phero, I carry). This term is applied to 



the Medusas, or Jelly-fishes, from their form ; and is sometimes used to 



designate the order of the Leeches (Hirudinea) from the suctorial discs 



which these animals possess. 

 DISSEPIMENTS (Lat. dissepio, I partition off). Partitions. Used in a restricted 



sense to designate certain imperfect transverse partitions, which grow from 



the septa of many corals. 

 DISTAL. Applied to the quickly growing end of the hydrosoma of a Hydro- 



