Di´a-toms [Gr. dia, through; tome, cutting.] Microscopic unicellular algæ inhabiting salt or fresh water. Each individual (frustule) consists of two flint valves which are more or less symmetrical. They are either isolated or attached together in a series.
Di-cot-y-le´don-es [Gr. dikotylos, with two hollows.] The most important and largest class of flowering plants. Characterized by having seeds with two cotyledons, exogenous stems, and leaves that are netted-veined; the parts of the flower mostly in fours or fives.
Di-del´phi-a [Gr. di-, two; delphys, womb.] A sub-class of mammals, as the Marsupials, having a double womb and no placenta.
Dif-flu´gi-a pyri-form´is [Lat. diffluere, to flow apart; pyrum, pear; forma, form.]
Di-no-sau´ri-a [Gr. deinos, terrible; sauros, lizard.] Mesozoic land reptiles.
Dip´no-i [Gr. di-, two; pneo, breathe.] Fishes with regular gills, a double or single lung, and nostrils inside as well as outside the mouth.
Dro-ma-the´ri-um [Gr. dromos, running; therion, small wild beast.]
Dys-chro-ma-top´si-a [Gr. dys, bad; chroma, color; opsis, sight.] Partial color-blindness; difficulty in distinguishing colors.
E-chi-no-der´ma-ta [Gr. echinos, hedgehog; derma, skin.]