S30 GLOSSARY. 



Dex'tbal (Lat. dextra, the right hand). Ei^ht-handed; applied to the direc- 

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



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

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

 and abdomen. 



Di-a-3te'jv[A (Gr. dia, apart; Tiistemi, to place). A gap or interval, especially 

 between teeth. 



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



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

 Di-a-to-ma'oe-^ (Gr. diatemno, I sever). An order of minute plants, which 



are provided with siliceous envelopes. 

 Di-bbanoh-i-a'ta (Gr. die, twice ; iragcMa, gills). The order of Cephalopoda 



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

 Di-otu-o-dos'ti-a (Gr. die, twice ; kuon, dog ; odous, tooth;. An extinct order 



of Eeptiles. 

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



comprising the Marsupials. 

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

 Dig-i-ti-&ea'da (Lat. digitus; gradior, I walk). A subdivision of the Car- 



nivora. 

 Dis'i-Ti-GEADB. Walking upon the tips of the toes, and not upon the soles 



of the feet. 

 Dim-e-ko-so'ma-ta (Gr. dis; mens, part ; soma, body)! Knotier ot 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 ibr the order. 

 DiM'Y-A-Kr (Gr. dis, twice ; mus, muscle). Applied to those bivalve Molluscs 



{LamelUbrancTdata) in which the shell is closed by two adductor muscles. 

 Di-ffi'oious (Gr. dis, twice; oikos, house). Having the sexes distinct; applied 



to species which consist of male and female individuals. 

 Diph't-o-doitt (Gr. dia, twice ; phuo, I generate ; odous, tooth). Applied to 



those Mammals whion have two sets of teeth. 

 DiPH-Y-o-zo'oiDS. Detached reproductive portions of adult Calycophoridw, aa 



order of oceanic Hydrozoa. 

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



the Lepidosiren. 

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



by the possession of two wings. 

 Diso'oiD (Gr. diehos, a quoit ; eidos, form). Shaped like a round jilate or quoit. 

 Di3-ooph'o-ba (Gr. dishos, a quoit ; pJiero, I carry). This term is applied to 



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



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



which these animals possess. 

 Dis-sEp'i-MENTS (Lat. dissepio, I partition off). Partitions. Used in a restricted 



sense to designate oertam imperfect transverse partitions, which grow from 



the septa of many corals. 

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



zoon ; the opposite, or "proximal," extremity growing less rapidly, and 



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

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



day. 

 Di-VEE-Tio'o-LrM (Lat. diverticulum, a by-road). A lateral tube with a blind 



extremity springing from the side of another tube. 

 Dob'sal (Lat. dorsum, baokj. Connected with the back. 

 Dob-si-beanoh'i-ate (Lat. dorsum, the back ; Gr. bragchia, gills). Having ex- 

 ternal gills attached to the back ; applied to certain Annelides and Moliuscs, 



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

 rectly employed. 



Eo'de-bon (Gr. ei>, out : deros^ skin). The outer plane of growth of the ex- 

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



