630 GLOSSARY. 



,T)ex'tbj\l (Lat. dextra^ the right hand). Kight-handod : applied to the direc- 

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



Di'a-phbaom (Gr. diaphragma, a partition). The " midriff," or the muscle 

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

 and abdomen. 



Di-a-ste'jia (Gr. &'o, apart ; liistemi, to place). A gap or interval, especially 

 between teeth. 



Di-as'to-le (Gr. diastello, I separate or expand). The expansion of a contrac- 

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



Pi-A-TO-MA'oE-iE (Gr. diatemno, I sever). An order of minute plants, which 

 are provided with siliceous envelopes. 



Di-beanoh-i-a'ta (Gr. dis, twice; bra^cJiia, gills). The order of Cephalopoda 

 (comprising the Cuttle-fishes, etc.), in winch only two gills are present. 



Dx-oyn-o-don'ti-a (Gr. dis, twice ; Icuon, dog ; odous, tooth;. An extinot order 

 of Eeptiles. 



Di-del'phi-a (Gr. dit, twice ; delphws, womb). The subdivision of Mammals 

 comprising the Marsupials. 



Dig'it (Lat. digitus, a finger). A finger or toe. 



DiG-i-Ti-eEA'DA (Lat. digitus; gradior, 1 walk). A subdivision of the Car- 

 nivora. 



Dia'i-Ti-GEADE. "Walking upon the tips of the toes, and not upon the soles 

 of the feet. 



Di5i-e-eo-3o'ma-ta (Gr. dis ; mens, part; «onio, body). A.not&er 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. 



Dm' y-a-et ( Gr. dis, twice ; mus, muscle). Applied to those bivalve Molluscs 

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



Di-(e'ciocs (Gr. dis, twice ; oihos, house). Having the sexes distinct; ap^ed 

 to species which consist of male and female individuals. 



Diph'y-o-dont (Gr. dis, twice ; pTmo, I generate ; odous, tooth). Applied to 

 those Mammals which have two sets of teeth. 



DiPH-Y-o-zo'oiDs. Detached reproductive portions of adult Calycophorid(e, an 

 order of oceanic Jlyd/rozoa. 



Dip'noi (Gr. dis, twice ; pnos, breath). The order of Fishes represented by 

 the Zepidosiren. 



Dip'tee-a (Gr. dis, twice ; pieron, wing). An order of Insects characterized 

 by the possession of two wings. 



Diso'oiD (Gr. dishos, a quoit ; eidos, foi-m). Shaped like a round plate or quoit. 



Dis-ooph'o-ea (Gr. dishos, a quoit ; phero, I carry). This term is applied to 

 the Medusa, or Jelly-tishes, from their form ; and is sometimes used to 

 designate the order of the Leeches {Hirudinea), from the suctorial discs 

 which these animals possess. 



Dis-sEp'i-MENTs (Lat. Ass«pjo, I partition off). Partitions. Used in a restricted 

 sense to designate certain imperfect transverse partitions, which grow from 

 the septa of many corals. 



Dis'tal. Applied to the quickly-growing end of the hj-drosoma of a Hydro- 

 zo'in; the opposite, or "proximal," extremity growing less rapidly, and 

 being the end by which the organism is fixed, when attached at aU. 



Di-de'nal (Lat. dies, day). Applied to animals which are active during the 

 day. 



Di-vEu-Tio'u-ixrai (Lat. diverticulum, a by-road). A lateral tube with a blind 

 extremity springing from the side of another tube. 



Doe'.9al (Lat. dorsum, back). Connected with the back. 



DoB-si-BEAifGH'i~ATE (Lat. doTSum, the back ; Gr^ brago/iia, gills). Having ex- 

 ternal gills attached to the back ; applied to certain Anndiden and Molluscs, 

 The term is of mongrel composition, and " notobranehiate " is more cor- 

 rectly employed. 



Eo'de-eon (Gr. eh, out ; deroSj skin). The outer plane of growth of the ex- 

 ternal integumentary layer (viz., the ectoderm, or epidermis). 



