HYPOLEPIS. 



[ 409 ] 



HYSTERIUM. 



growing underground, and by their fleshy 

 indehiscent receptacle, which is excavated 

 into sinuous cavities lined with basidio- 

 spores. which are sometimes smooth and 

 sometimes tuberculated (figs. 352, 353). 



See PL 27. fig. 8. 



BIBL. Tulasne, L. K. & 0., Fungi Hypo- 

 gcei, Paris, 1851 ; Ann. Sc. N. 3 ser. xv. 267, 

 and Ann. N. H. 1851, vol. viii. 19; Berk. 

 Outl, 292. 



HYPOLE'PIS, Bernh. A genus of 

 Pterideae (Polypodiaceous Ferns), remark- 

 able as varying in the condition of the 

 indusiuni so as to become undistinguishable 

 from Polvpodium. Seven species, tropical. 

 (Hooker," Syn. 129.) 



HYPOMY'CES, Tul. A genus of Py- 

 renomycetes (Ascomycetous Fungi), pro- 

 posed by Tulasne to include the coloured 

 species which are parasitic and spring from 

 a thick floccose mycelium. Their conidia 

 are often extremely curious, and have been 

 referred to Sepedonium, Asterophora, Dac- 

 tylium, &c. The species were formerly 

 included in Hypocrea. 



BIBL. De Bary, Bot. Zeit. 1859, 385, 393 ;* 

 Tul. Carp. iii. 38. 



HYPOPTERYGIA'CEJE. A family of 

 Pleurocarpous Mosses with a peculiar ar- 

 rangement of the leaves, which are placed 

 in two opposite straight rows united on the 

 upper side of the stem, with a third median 

 row of smaller stipuliform leaves on the 



Fig. 355. 



Hypopterygium. 

 Fig. 354. Natural size. 

 Fig. 355. A leafy branch. Magnified 5 diams. 



under side, bearing a resemblance to the in- 

 termediate leaves in Selaginella (figs. 354, 



355). The cells of the leaves are parenchy- 

 matous and equal in all parts. The genera 

 are all exotic, viz. Hypopterygium, Cyatho- 

 phorum, and Helicophyllum. 



HY'POPUS, Dug. A formerly supposed 

 genus of Acarina, and family Acarea. 



Char. Body ellipsoidal, coriaceous ; palpi 

 absent; labium oblong, prolonged in the 

 form of a rostrum, and furnished with two 

 long anterior rigid setae ; the posterior pairs 

 of legs but little developed. The forms are 

 numerous, and are found as parasites upon 

 both animals and plants, as Arvicola (the 

 field-mouse), Bombus (the humble-bee), 

 Musca (fly), some Myriapoda, and even 

 upon other Acarina; also upon ferns, &c. 

 Dujardin supposed that they were young 

 forms of Gamasus; Claparede that they 

 were the males of certain Acarea ; while 

 Megnin decides that they are the nymphs 

 of Acari (Tyroglyphus, &c.). They have 

 no mouth nor digestive organs ; but are 

 furnished with posterior ventral suckers. 



PI. 6. fig. 15 represents a Hypopus mus- 

 carum, which we found upon a house-fly 

 (Musca domestica). 



BIBL. Duges, Ann. Sc. Nat. 2 se"r. i. 20, 

 ii. 37 ; Gervais, Walckenaer's Arachn. iii. 

 265 ; Dujardin, Ann. Sc. Nat. 3 ser. xii. 

 243 & 259 ; Claparede, Zeitschr. wiss. Zool. 

 1868, xviii. 445 ; Murray, EC. Ent. 231 j 

 Megnin, Paras. 146. 



HYPOTHE'CIUM. The term applied 

 to the layer of cellular tissue, on which are 

 attached the thecaa or spore-sacs of the 

 fruits of the LICHENS. 



HYPOX'YLON, Fries. A genus of 

 Sphseriacei (Ascomycetous Fungi), distin- 

 guished by a sessile stroma, separate and 

 distinct from the matrix (see SPHJERIA). 

 The Hypoxyla of Bulliard with an erect 

 stroma belong to XYLARIA. 



HYSTE'RIUM, Tode. A genus of Pha- 

 cidiacei (Ascomycetous Fungi), distin- 

 guished by the elliptical or elongated peri- 



Fig. 356. 



Fig. 357. 



Hysterium degenerans. 



Fig. 356. Natural size. 

 Fig. 357. Perithecium. 



Magnified 10 diameters. 



thecia (figs. 356, 357), bursting by a sim- 

 ple longitudinal slit. The species are nu- 

 merous, growing upon (usually dead) bark, 



