RHOIKONEIS. 



[ 659 ] 



EICCIA. 



a central iiodulo in the curved side. R. cur- 

 vata (PI. ry2. iig-. 1')). 



BiiiL. liabenht. Ahj. i. IVI. 



RIIOIKONE'IS, Grim.— A subgenus of 

 Achnantludiiim, comprising two species^ 

 found iu the Nortli Pacific. 



BiBL. Rabouht. Alf/. i. 109. 



RIIO PALOM Y 'CES,Corda.— A genus of 

 Mucedines (Ilypliomycetous Fungi), nearly 

 allied to AsPEiiaiLLrs, but having the 



Fig. 618. 



Fig. 619. 



Rhopalomyces nigra. 

 Fig. 618. Tufts on wood. Nat. size. 

 Fig. 619. Fertile filaments. Magnified 200 diameters. 



spores single (fig. 619), and not in monili- 

 form series. The single spores are borne j 

 on minute spines (fig. 619, left-hand head), i 

 They are mildews growing over decayed | 

 wood, matting, dung,"&c. Two new British 

 species are described by Berkeley and 

 Broome, found growing together. 



BiBL. Berk, and Broome, Aidi. N. H. 2. \ 

 vii. d'6, pi. 5. 



RHOPALOSI'PHUM, Koch.— A genus ; 

 of Aphidte. Six species, on the currant and 

 goosebeiTV, Sonckm, Alisnia, Ligustrinn, 

 and JBerheris. (Buckton, Ajjhidce, Eai/ Sac. 

 ii. 9.) 



RHUBARB.— Garden rhubarb (Meum 

 tindulafiaHfiind other species) afibrds, in the 

 large edible petioles, excellent specimens of 

 SpiRAX-tibrous Structures, spiral, an- 

 nular, and reticidate vessels and ducts : these 

 are readily isolated by the help of a needle 

 from a fragment of cooked rhubarb placed | 

 in water on a slide, and are well seen by 

 polarized light. The petioL.'S and leaves 

 I^Lkewise contain bundles of acicular Ra- 

 PHiDES. The roots also contain special 

 receptacles for a characteristic secretion. 



RHYNCH.E'TA, Zenker.— A genus of 

 Acinetina. Body ovate, free or attached, 

 Avith a long anterior suctorial tentacle. Ii. 

 ci/clujnon, freshwater, on Ci/cloj)-". (Kent, 

 inf. 800,) 1 



RHYNCHOL'OPHUS, Duges, = Eri/- 

 thrceus, Latreille (not Duges). A genus of 

 jV.raclmida, of the order iVcariua, and family 

 Trombidina. 



C7uir. Palpi large, free ; labium penicil- 

 late ; mandibles ensiftn-m, very long; body 

 entire ; cox;e very remote, legs palp-like, i. e. 

 dilated at the end, posterior very long. 



Species numerous ; foimd iu woods, under 

 leaves, and iu mosses. 



Ii. citiereus (PL 6. fig. 40 : «, labium with 

 palp ; h, tarsus ; c, plume of labiimi more 

 magnified; d, mandible). 



BiBL. D-iges, Ann. Sc. Nat. 2. i. 30; 

 Gervais, TVulokenaer's Aradodd. iii. 175 ; 

 'K.och, Deiitsclil. Crust.; ^Iwixiw, Econ. Ent. 

 124. 



RIIYNCHONE'MA, Ktz.— A genus of 

 Zygnejiaceje (which see). 



BiBL ; Rabenht. Akj. iii. 229. 



RHYNCHOP'AGON, Werneck (Rota- 

 toria) =i)/(//e?ia with a bilobed roitrum ! 

 Two species. (Werneck, Ber. L'crl. Ak. 

 1841, 377.) 



RriYNCIIOP'ORA, = Lcin-alia pt. R. 

 hispinosa^i L. bisp. 



RHYNCHO'PRION. See Pulex. 



RHYTIS'MA, Fries.— A genus of Phaci- 

 diacei (Ascomycetous Fungi) , growing upon 

 the leaves of trees and shrubs, forming dark 

 patches or spots on the surface, breaking 

 through the epidermis with little scales or 

 irregular fissures. J?, acerinum is exceed- 

 ingly common, forming large black spots on 

 the leaves of the sycamore and maple; the 

 thecasporous fruit is perfected (on the di;ad 

 fallen lea\es j in spring ; Melasjua acerina, 

 which occurs in autumn, appears to be a 

 preparatory form of this plant. R. salici- 

 nuin is common on willow-leaves. 



BiBL. Berk. Br. FI. ii. pt. 2. 290 ; Grev. 

 Crypt. Fl. pL 118; Fries, >S'i«wi. Vey. .'570; 

 Tulasne, Covipt. Rendus, 1852 {Ann. N. H. 

 2. viii. 118) ; Coruu, Comjd. Rend. 1878, 

 Grevilka, vii. 100. 



RICASO'LIA.— A genus of Phyllodei 

 (Lichenaceous Lichens). 



Char. Thallus lobate or laciuiate, affixed 

 by fasciculate rliizinte ; gouidia small , yellow- 

 green ; spores 1-3-septate. (Leighton, Brit. 

 Lkh. Flora, 112.) 



RICCIA,L.— Agf-uus of Riccieaj (Ilepa- 

 ticte), consisting of minute green thalloid 

 productions growing upon damp ground or 

 tloating on water, distinguished from the 

 allied forms by the capsules being immersed 

 iu the sub.~tance of the frond, dc'stitute of 

 perichajte and perigoue, while the archegon(; 



2u2 



