HYDROZOON 



176 



HYOPOTAMTTS 



Aquatic animals, forming a division of Coe- 

 lenterata, resembling the hydra, and con- 

 sisting of layers of cellular tissue, enclosing 

 a digestive cavity, the mouth of which is 

 usually surrounded by tentacles; mostly 

 marine. Compound /7.=Corallines. Classifi- 

 cation of H. by Huxley: Hydrophora, Sipho- 

 nophora, Discophora, Trachymedusae. 



Hydrozoon, (hi-dro-zo'on). [Hydro and Zoon, 

 q.v.] An individual of Hydrozoa, q.v. 



Hydrurets, (hi-dro'rets). [Hydrogen, q.v.]= 

 Hydrides, q.v. 



Hydrus, (hl'dnis). [The Latin word.] l.rs 

 Water-serpent: a constellation. 2. A serpent 

 with maxillary teeth and poison fangs. 



Hygeia, (hij-e'a). [Classical.] No. 10 of the 

 Minor Planets. 



Hygre, (hi'gr). [Gk. hygros, wet.] := Bore, q.v. 



Hygrometer, ( hi-grom'e-ter ). [Gk. hygros, 

 wet; Meter, q.v.] An instrument used for 

 hygrometry. Chemical H.: some substance, 

 guch as calcic chloride, which absorbs mois- 

 ture. Daniell's H.: two glass bulbs, one 

 containing ether, which is cooled by eva- 

 poration until dew is deposited on the out- 

 side. Observatory H.: two bits of wood glued 

 together, which move to or fro according 

 as the dampness increases or diminishes. 

 Jiegnault'i H. resembles Daniell's H., but 

 of silver. 



Hygrometric, (hi-gr5-met'rik). [Hygrometer, 

 q.v.] 4 



Hygrometry, (hi-grom'e-tri). [Hygrometer, 

 q.v.] The measurement of the amount ot 

 aqueous vapour in the air, either by absorb- 

 ing the moisture from a given quantity of 

 air, by finding the point at which dew is de- 

 posited, or by a psychrometer. 



Hygroscope, (hi'gros-kop). [Gk. hygroi, wet; 

 skopeo, 1 show.] An instrument for show- 

 ing the increase or decrease of moisture in 

 the air. 



Hyk=Cepheus: one of the northern constel- 

 lations. 



Hyla, (hi'la). [Gk. hyla, forest. ]= Tree-frog: 

 an animal, belonging to Anoura, found in 

 S. America and Australia; not known in S. 

 Africa or India; can climb trees by means of 

 suckers on toes. II. ar6orea=Rana arborea 

 = Tree-frog. 



Hylaeosaurus, (hT-le-o-saw'rus). [Gk. hyla, 

 forest ; saurus, lizard.] = Forest-lizard : a 

 reptile, known by fossil remains found in 

 Wealden rocks, belongs to Deinosauria. q.v. 



Hylerpeton, (h i-ler'pe-ton). [Gk. hyla, forest; 

 herpeton, reptile.] A land animal of the coal 

 period, probably a reptile somewhat adapted 

 to an aquatic life, known only by some bones 

 of the head and a few other bones. 



Hylobates, (hl-lob'a-tez). [Gk. hylobates, wood- 

 walker.]=Gibbon: an arboreal monkey be- 

 longing to Catarhina. II. agilis: a gibbon 

 able to sing an octave of half notes. 



Hylodes, (hl'lo-dez). [Hyla, q.v.] A tree- 

 frog, an American variety of which lays its 

 eggs singly in axils of leaves of trees. 



Hylonomus, (hi-lon'o-mus). [Gk. hyla, forest; 

 nomos, dwelling.] A small reptile, 5 or 6 

 inches long, found in coal of Nova Scotia. 



Hylorana, (hi-lor-a'na). [Gk. hyla, forest; 



rana, frog.] H. jerboa: the thinnest of all 



frogs and toads. 

 Hylotoma, (hl-lot'o-ma). [Gk. hyla, forest; 



tomeos, cutter.] An insect belonging to 

 Hymenoptera. H. ro=Rose saw-fly. 



Hymen, (hi'men). [Gk. hymen, membrane.] 

 A fold of mucous membrane closing the 

 entrance to the vagina. 



Hymensea, (hl-men-e'a). A tree, belonging to 

 Leguminaceae, from some species of which 

 copal is obtained. 



Hymenia, (hl-men'i-a). Plural of Hymenium, 

 q.v. 



Hymenium. (hT-men'i-um). [Gk. hymen, mem- 

 brane.] The fruit bearing surface of fungi, 

 as on the under side of a mushroom; usually 

 somewhat membraneous. 



Hymenocaris, (hl-men-ok'a-ris). [Gk. hymen, 

 membrane; karis, shrimp.] A phyllopod 

 crustacean animal, found only in Lingula 

 flags. 



Hymenomycetes, (hl-men-o-ml-se'tez). [Gk. 

 hymen, membrane; mykes, mushroom.] = 

 Toadstools, mushrooms, &c.: plants, forming 

 a primary division of Fungales, having the 

 jujivlinm in the ground; the receptacle is 

 the visible part. 



Hymenophore, (hl'men-o-for). [Gk. hymen 

 membrane; phoreo, I bear.] The combined 

 stem and pileus, as in mushrooms. 



Hymenophyllacece, (hl-men-o-fil-la'se-e). [II y- 

 menophyllum, q.v.] A family of ferns, q.v. 



Hymenophyllum, ( hI-meu-6-fil'lum ). [Gk. 

 hymen, membrane; phyllon, leaf.]=Filmy- 

 fern: a plant, the type of Hyraenophyllacece, 

 named from its pellucid fronds. 



Hymenoptera, (hl-men-op'ter-a). [Gk. hymen, 

 membrane; pteron, wing.] Bees, ants, &e. : 

 insects with four membraneous wings; very 

 numerous, and mostly small; mandibles and 

 maxillae for mastication; complete metamor- 

 phosis females have a sting; includes 3000 

 species. 



Hyocholeic acid, (hl-o-kol'Ik). [Gk. hys, pig; 

 chole, bile.] C^H^NC^S: an acid, contain- 

 ing sulphur, obtained from pig's bile. 



Hyocholic acid, (hT-o-kol'ik). [Gk. hys, pig; 

 chole. bile.] C^H^NOj: an acid obtained 

 from pigs' bile. 



Hyodyslysin, (hI-6-dislis-in). [Gk. hys, pig; 

 Dyslysin, q.v.] CsdR^O^ : a resinous sub- 

 stance derived from hyocholic acid. 



Hyoglossal, (hi-6-glos'sal). [Hyoid and Glos- 

 sal.] //. membrane: connects tongue and 

 hyoid bone. H. muscle: connects tongue 

 and hyoid bone. 



Hyoid, (lii'oid). [The Greek letter f, eidox, 

 form.]=Lingual bone: a bone, supporting tho 

 tongue, which in man has somewhat the 

 shape of the letter U. 



Hyoidean, (hi-oid'e-an). [Hyoid, q.v.] H. 

 arch ; in the skull. H. nerve ; a division of 

 the glossopharyngeal nerve. 



Hyopotamus, (hl-o-pot'a-mus). [Gk. hys, hog; 

 potamus, river. ]= Ancodus=Cyglognathus= 

 Bothriodon=:Anthrocotherium : a hog-like 

 animal with four digits on each limb, known 

 by fossil remains, teeth, in Lower Miocene. 



