HERPETIUM. 



[ 323 ] 



himanthalia. 



the corpuscles in the adjoining upper margin 

 of each valve appear to be crowned or 

 covered by setse or opposite membranes. 

 These forms divide in the siliceous manner 

 of the MelosircE, but not beneath a deciduous 

 integument (hoop). 



H. mammillaris. Valves not striated, with 

 about twenty simple opposite setae at the 

 middle of the base, longer than the mammillse 

 and inserted into their margin, obvallate ; 

 diameter 1-810". Bermuda. 



BiBL. Ehrenberg, Ber. d. Berl. Akad. 

 1844, p. 262. 



HERPETIUM, Nees.— A genus of Jun- 

 germannieae (leafy Hepaticaceae), distin- 

 guished by the incubous bilobed leaves not 

 being folded together, and by the obtusely 

 three-angled perigone. Two Brit, species : 



1. H. reptans {hepidozia, Dumortier). 

 Leaves squarish, acutely two or four-toothed 

 at the end. Woods and shady places. Jun- 

 germannia reptans, Hook. Brit. Jungerm. 

 pi. 75. 



2. H. trilobatum [Mastigohryum, Nees). 

 Leaves ovate, three-toothed at the summit. 

 Moist alpine spots. J. trilobatum. Hook. 

 Brit. Jung. pi. 76. 



BiBL. Hooker, Brit. JungermannicE, I. c; 

 Endlicher, Gen. Plant, nos. 4/2-9; Ekart, 

 Synops. Jungermann. pi. 3. figs. 21, 22. 



HETEROMITA, Duj.— A genus of Infu- 

 soria, of the family Monadina. 



Char. Body globular, ovoid, or oblong, 

 with two filaments arising from the same 

 point in front ; one, more delicate, and with 

 an undulatory motion, causing progression ; 

 the other thicker, and floating freely behind, 

 or adhering here and there to the slide, so 

 as to produce by its contraction sudden mo- 

 tion backwards. 



Distinguished from Anisonema and Hete- 

 ronenia by the absence of a tegument, shown 

 by the glutinous appearance of the entire 

 mass of the body, the facility with which it 

 adheres to other objects and becomes drawn 

 out, and the presence internally of certain 

 corpuscles which can only have entered by 

 vacuolae formed on the surface. 



Found in both fresh and salt water. 



H. ovata = Bodo qrandis, E. (PL 23. fig;. 

 18 a). 



H. granulosa. Body globular, surface 

 granular; marine; length 1-2300". 



H. angusta. Body lanceolate, slightly 

 sigmoid; aquatic; length 1-980". 



BiBL. Dujardin, Infus. p. 297. 



HETERONEMA, Duj.— A genus of In- 

 fusoria, of the family Euglenia. 



Char. Form variable, oblong, irregularly 

 expanded posteriorly ; with a slender flagel- 

 liform filament, and a thicker trailing, re- 

 tracting filament. 



Tegument obliquely striated. 



Difi'ers from Heteromita in the presence of 

 a tegument, and from Jnisonema in the tegu- 

 ment being contractile. 



H. marina (PI. 24. fig. 17). Filaments 

 longer than the body ; length 1-4300". 



BiBL. Duj ar din, Infus. p. 370. 



HEXAMITA, Duj.— A genus of Infusoria, 

 belonging to the family Monadina. 



Char. Body oblong, rounded in front, 

 constricted and bifid or indented behind; 

 two or four flagelliform filaments arising 

 separately from the anterior margin, the two 

 jDosterior lobes being prolonged into flexuous 

 filaments. 



H. nodulosa (PI. 24. fig. 20). Oblong, 

 with three or four longitudinal rows of no- 

 dules; motion vacillating ; length 1-1800". 

 In decomposing marsh-water. 



H. inflata. 



H. intestinalis. Fusiform, prolonged into 

 a bifid tail; length 1-2100". In the intes- 

 tines and peritoneal cavity of the Batrachia 

 and Tritons. 



BiBL. Dujardin, Infus. p. 296. 



HILDENBRANDTIA, Zanardini. — A 

 genus of Nulliporous Corallinaceae (Flori- 

 deous Algae), containing one British species, 

 H. sanguinea, Kiitz. {H. ridjra, Meneghini) : 

 common, in the form of a bright or dark 

 red membranous crust, at first circular, after- 

 wards spreading irregularly over smooth 

 stones and pebbles. The frond is about 1-20" 

 thick in the middle and thinner toward the 

 edges, and composed of minute globose cells, 

 partly vertically, partly horizontally arranged. 

 It is not stony. It has immersed concep- 

 tacles, pierced by a pore (fig. 254. p. 266), 

 containing tetraspores and paraphyses. 



BiBL. Harvey, Brit. Mar. Alg. p. 110. 

 pi. 14 C, Phycolog. Britann. pi. 250, Ann. 

 Nat. Hist. xiv. pi. 2. (as Rhododermis 

 Drummondii) ; Kiitz. Phyc. generalis, pi. 'JS. 

 fig. 5. 



HILUM. — This name is appHed to the 

 surface of attachment of the funiculus of 

 seeds, which is seen as a kind of scar, more or 

 less distinct. Sometimes it coincides with 

 the chalaza or organic base of the seed, 

 sometimes, where a raphe exists, it is near 

 the micropvle. (See Ovule.) 



HIMANTHALIA, Lyngbye.— A genus of 

 Fucaceae (Fucoid Algae), remarkable for the 

 peculiar forms of the frond and receptacle, 



y2 



