I 



JITDROCTOIT 



BTDROPHItlDJK. 



160 



what ground* U Dot sUted. The fresh juice act* as an emetic. It is 

 ^ij po*sea an aromatic odnur and an mien* bio taste. The species 

 of fferime***! are easily cultivated ; they must all be kept moist 

 The stole creenhonn and frame kinds ihould be grown in pote placed 



t DOB*. KtU*myit*tt U ; Burnett, OM** ; Babington, Manual 



H TDROCYoS, a genus of FUhee belonging to the tfalafOfterygii 

 Jrirraifrtifrf The cpeciee are very numerous. They have the point 

 of the muttl* formed by the intermaxillarie*, the maxilUries nearer, 

 before the eyes, and completing the aperture ; the tongue and vomer 

 S the jaw* with conical teeth, and the Urge itiborbitel covers 



They are also found in 



HYDRODICTYOX. [AujJL] 



HYDROIDA, a name given to a lection of the order Polyplftra, 

 embracing form* resembling the fresh-water Hydra in the simplicity 

 of their organisation. The following U Dr. Johnston's arrange- 

 ment of the familie* of British Zoophytes referred to the 



Ovine* or bulbule* naked, bud-like, pullulating from the 

 base* of the tentacula. 



, Khrenberg (T*b*laria, Linnaeus; Ttbulariada, John- 



. Lea Tubulaires, Van Beneden). 

 Family L Polype naked, or with only a rudimentary polypidom. 



_ ... like an opereulum. 



A large number of sp*cie* inhabit BnuiL 



Tabu- 



t Polypi naked. 



The tentecuU scattered. Clara. 



The tentacula in one row. Hydrattinia. 



H Polyps with a horny cuticle. 



The tentacula with globose tips. Coryne. 



The tentacula filiform. Cordylophora. 



Family II. Polypidom fistular; the tentacula whorled. 

 Uriada. 



t The tentacula in a single whorl Eudcndrium. 

 ft The tentecuU in a double whorl. 



Polypidom rooted. Tubularia. 

 Polypidom unrooted and deciduous. Corymorpha. 



** Orisac* in the form of homy capsules or vesicle* Mattered on the 



polypidom*, and deciduous. 



f*rl*lari*a, Ehrenberg (Strtvlaria, Linnaeus). 



Family III. Cells of the polyp senile. Sertulariada. 



t Cells bUerial 



Celb alternate, tubular. Jfalecium. 



CelU vasiform, everted. Sertularia. 



CelU conico- tubular, appressed. Thuiaria. 



ft CelU uniseriaL 



The branchlrU plumose or pectinate. Plmnutaria. 

 The branchleta whorled. Antmnulana. 



Family IV. Polype-cells on ringed stalks. Campanulariada. 



CelU alternate, campanulate. Laomedea. 



Celb irregular, or whorled. Campanalaria. 



Polype propagating by bud* and ova, which develop themselves 



on and in the body of the parent. 



Ilfdrima, Ehrenberg (Hydra, Linnaeus; Ilydraida, Johnston). 

 One gem* only. Hydra. [HTDRA; Poi.TnrKBi.] 



HTDROLBA'CS^, a very small and unimportant natural order 

 of Monopetelou* Exogenous Plant*, which are by mo*t authors 

 united with //jrfrotAjrf&Kwr. [HTDBOPBTLLACKJC.] They are weeds 

 *l>^Hn; the East Indie*, with alternate glandular or stinging 

 leave*, mooopetelon* regular flower*, with a gyrate inflorescence, 

 definite stamen*, a superior polyspermou* 2- or 3-celled fruit, and 

 ' i with UM embryo lying in the midst of fleshy albumen. In 



rir Jty*" infloneoenoe they oomepond with Boragincuxat, 



IIYI'KOLITE. [OkOUnn.] 



IIYKKUM .. [UAOKCtm.] 



HYDROMETRID^, a family of Insect* belonging to the 

 order Utmifttru. This family wa* esteblisbed by Dr. Leach, and is 

 thus characterised : Rostrum with 8 or 3 dUtinct joint* ; labrum 

 very short ; eyes moderate ; feet very long, formed for walking on the 

 water, with UM claws minute, inserted laterally into a fissure on the 

 extremity of the terminal jointvf the term*. 



The ( wra //jrfrnsrfno, Otrrii, and VMa of Latreille belong to thU 

 <>?; Thoee *peeie* which have seteoeou* antenna, the head pro- 

 loafMl bHo a snout and reoeiving the roetrum beneath, belong te the 

 ftnt of these three genera, of which the J/ydromdm *ag*or*m will 

 M an illoetraUon. thi* insect U about 34th* of an inch in 

 not broader than an ordinary cited pin, of a black or 

 r, with pale brown leg*, and U very common on pond* 



I dita-a, gmlly neer UM margin. Like the other species of the 



Ifyili ulrit tfiinosa, 



1, s flower, geen from beneath; 2, a stamen; 3, n ripe seed-reatel ; 4, a 

 section of a seed, shoving the embryo. 



family Hydrometrida, it possesses the power of walking upon the sur- 

 face of the water : it differs however from those of the two remaining 

 genera, inasmuch as its movements are comparatively slow. 



In the genus Vtlia the antenna. 1 are aliform, 4-jointed, the first joint 

 the longest, the remaining joints long, about equal to each other, ami 

 bent at an angle with the first ; rostrum 2-jointed ; legs moderate, 

 and nearly equidistant. 



> r . riru/oritro (Latreille) U a very common insect, in this country, 

 frequenting running streams, and running on the surface of the 

 with great rapidity. It is about l-4th of .an inch in length, and 1-1 2th 

 of an inch in breadth ; of a black colour, the body red, spotted with 

 black, the thorax brown, with two white spots, and the elytra each 

 with four white spoU. 



The principal characters of the genus Gtrrit are Antennrc filiform, 

 4-jointed, the basal joint nearly as long as the remaining three ; ros- 

 trum 3-jointed, legs long, the second pair the longest, and inserted far 

 from the first. 



(J. Paludum is about 5-Sths of an inch in length, and 1-1 2th of an 

 inch in breadth, of a brownish-black colour above, and silvery-white 

 beneath. This insect is very abundant, and it* peculiar habits of 

 darting about on the surface of the water must have attracted the 

 attention of all persons. Its food appears to consist chiefly of such 

 insects as are blown or accidentally fall into the water, which it seize* 

 with its fore legs. 



HYDBOPELTID*U& Waterthiddt, a natural order of Exogenous 

 Plant* (Cabombacea of Torrey, Gray, and Lindley). The species 

 are nquatic plants, with floating peltate leaves. Flowers axillary, 

 solitary, yellow, or purple. Sepals 3 or 4, coloured inside. Petals 3 

 or 4, alternate with the sepals. Stamens definite or indefinite, 

 hypogynour, arising from an obscure torus. Anthers linear, turn. -.1 

 inwards, continuous with the filaments. Carpels 2 or more, termi- 

 nated by a short style. Ovules orthotropal, pendulous. Fruit inde- 

 hirccnt, tipped by the hardened style. Seeds definite, pendulous. 

 Embryo minute, 2-lobed, inclosed in the fleshy sac of the amnios, 

 at the apex of the nucleus, and external to an abundant fleshy 

 albumen. There can bo no doubt of the near relationship of these 

 plants to the Water-Lilies. They are American water-plants, found 

 from Ouyana to New Jersey, and also on the coast of Australia 

 beyond the tropics. 



Hydropdtit purpurea It said to be nutritious, but slightly Astringent. 

 The leaves are employed as a remedy for phthisis and dysentery. 



(Lindley, Vrgetablt Kingdom.) 



HTDBOPKLTia IHrraontanal 



IIVIiUnl-HANK. [SILICA.] 



HYimOPHI'LlD^a family of Coleopterous Insects establishe.l 

 by Leach. The insects of this family are included by Latrvillo in 

 hui section Palpicorncl. They have generally nine joints to the 

 antennae, but sometimes only 6 ; the terminal joints always form a 

 pcrfoliated knob ; the maxillary palpi arc very long and slender; tho 



