HELLEBORUS. 



[ 317 ] 



HEMIAULUS. 



ings in the centre, but with as many large 

 submarginal apertures (?) as there are rays, 

 and with numerous erect opposite submargi- 

 nal spines on each side. The spines connect 

 the pairs of young frustules ! 



H. metii. Frustules with six septa and 

 rays, three of the inter\^als raised and coarsely 

 cellular, the alternate ones impressed with 

 fine decussating lines, the limb of the radiate 

 margin broad ; marginal spines in the middle 

 of each cellular interval one or three, in the 

 others two or four ; umbilical star slightly 

 angular; diameter 1-370". Bermuda. 



Three other species, with a different num- 

 ber of rays. 



The different appearances of the markings 

 upon the elevated and depressed portions of 

 the valves evidently arise from the existence 

 of the ordinary depressions seen naturally by 

 oblique and direct light. 



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

 1844. p. 262. 



HELLEBORUS, L.— A genus of Ranun- 

 culaceae. The cuticular layer of the epider- 

 mis of the leaves of H.foetidus exhibits cu- 

 rious waved ridges (PI. 21. fig. 9). See 

 Epidermis, of Plants. 



HELMINTHOSPORIUM, Link.— A ge- 

 nus of Dematiei (Hyphomycetous Fungi) 

 growing on rotten wood, &c., of which nu- 

 merous species are found in Britain. The 

 mycelium is often somewhat gelatinous or 

 indistinct ; on it arise (often aggregated) 

 erect, rigid, septate filaments (fibres), on the 

 summits of which stand large, often club- 

 shaped septate spores. Br. species : 



1. H. macrocarpum, Grev. (Grev. Sc. 

 Crypt. FL pi. 148. fig. 1). 



2. H, subulatum, Nees (Nees, Nova Ac- 

 ta, ix. pi. 5. fig. 13). 



3. H. Clavariarum, Desm. (Desmazieres, 

 Ann. des Sc. nat. 2 ser. ii. pi. 2. fig. 2). 



4. H. velutinum, Link (Grev. Sc. Crypt. 

 Fl. pi. 148. fig. 2). 



5. H.fusisporium, Berk. (Br. Flora,vo\. ii. 

 part 2. p. 336). 



6. H. nanum, Nees (Nees, Nova Acta, ix. 

 pi. 5. fig. 13 B ; System, fig. 65). 



7. H. simplex, Kunze (Nees, /. c. fig. 11). 



8. H. TilicB, Fr. (Berkeley, Annals Nat. 

 Hist.yi.^\. 13. fig. 18). 



9. H. folliculatum, Corda (Corda, Icon. 

 Fung. i. pi. 3. fig. 180). 



10. H. ohovatum, Berk. (Ann. Nat. Hist. 

 vi. pi. 13. fig. 19). 



11. H. delicatulum, Berk. (I. c. fig. 20). 



12. H. Smithii, Berk. & Broome (Ann. 

 Nat. Hist. 2 ser. vii. pi. 6. fig. 5). 



13. H. turbinatum, Berk, and Br. (/. c. 

 fig. 6). 



14. H. Rousselianum, Montague (Ann. des 

 Sc. nat. 3 ser. xii. p. 300). 



15. H. sticticum, Berk, and Br. {Ann. Nat. 

 Hist. 2nd ser. xiii. pi. 15. fig. 10). 



BiBL. Berkeley, Brit. Flora, iii. pt. 2. 

 p. 336 ; Fries, Systema, iii. p. 354, and Sum- 

 ma Veget. p. 500, and the works above cited. 



HELMINTHOSTACHYS, Kaulf. — A 

 genus of Ophioglossaceous Ferns, distin- 

 guished by the complex spikes bearing 

 crested sporanges. 



Fig. 318. 



Fig. 319. 



Helminthostachys zeylanica. 



Fig. 318. Fragment of a spike with sporanges 

 fied 10 diams. 

 Fig. 319. A portion still more magnified (20 diams) 



Magni- 



HELVELLACEL— A family of Ascomy- 

 cetous Fungi, approaching to the Hymeno- 

 mycetes in outward form, but distinguished 

 at once by their fructification. See Asco- 



MYCETES, SpATHULEA, LeOTIUM, StIC- 



Tis Propolis 



HEMELYTRA. — The anterior pair of 

 wings of the Heteropterous division of the 

 Hemiptera. See Insects. 



HEMEROBIUS,Linn.-A genus of Neu- 

 ropterous Insects. 



Hemerobius ( Chrysopa) perla, one of the 

 lace- winged flies, has very thin, transparent, 

 and beautifully netted iridescent wings, in 

 which the circulation can be well observed ; 

 the wings also exhibit well the tracheae in 

 the veins. The larva feeds upon Aphides. 



BiBL. Westwood, Introduction &c. ; 

 Bowerbank, Entom. Mag. iv. 



HEMIAULUS, Ehr.— A genus of Diato- 

 maceae. 



Char. Frustules single, compressed, sub- 

 quadrate, with two tubular processes on each 

 side, the ends of those (the shorter) on one 

 side being open, the others closed ; not con- 

 stricted at the sides. 



