EAPHIDES. 



[ 053 1 



RATTULUS. 



charge the crystals. Turpin erroneously 

 described these as organs of a special nature, 

 under the name of Biforines. 



Raphides most frequently consist of oxa- 

 late of lime, especially in the Cactacese, 

 Polygonaceae, &c. ; carbonate of liine seems 

 to stand next in the order of frequency, 

 mostly in the form of granules, only recog- 

 nizable under polarized light with the 

 crossed nicols ; then sulphate and phosphate 

 of linie. Their composition may be ascer- 

 tained by the appropriate tests for these 

 salts. It is sometimes difficult to determine 

 the form accurately, on account of the small j 

 size ; it is found "advantageous to mount 

 well-cleaned and partly crushed crystals in 

 Canada balsam, also to view them rolling 

 over in alcohol (!NTB. p. xxxiii). 



The peculiar crystalline structures called 

 cystoliths, occur most abundantly in the 

 families of the Urticaceae (including Moreae) 

 and the Acanthaceae. They ordinarily con- 

 sist of a stalked, clavate, and globose, or 

 irregular linear body, suspended in a greatly 

 enlarged cell, most frequently situated 

 beneath the epidermis of the leaf (PL 48. 

 figs. 26, 27) ; but they also occur in deeper- 

 seated regions. Their nature and develop- 

 ment have been followed by several ob- 

 servers ; and they are found to consist of a 

 cellulose matrix with carbonate of lime crys- 

 tallized in a kind of efflorescence upon the 

 surface. They appear to originate by a little 

 papilla or column of secondary deposit at 

 the upper end of the cell, which increases 

 by successive concentric layers of cellulose 

 applied on the lower surface, leaving a short 

 stalk-like portion which remains uncovered 

 and also free from the crystals which gradu- 

 allv sprout out from the thickened head. 

 The crystals may be removed by the action 

 of acid ; and then the matrix assumes a blue 

 colour with sulphuric acid and iodine. Payen 

 imagined the thicker portion incrusted by 

 the crystals to be composed of numerous 

 cellules, eacli producing a crystal : this is 

 erroneous. The cystoliths vary in form : 

 the clavate kinds may be best observed in 

 Ficus elastica (PI. 48. fig. 27) and other 

 species, in vertical sections of the leaf; 

 globular forms are found in Parietaria offi- 

 cinalis (fig. 26) and the Hop ; in species 

 of Pilea they are linear or crescentic, and 

 suspended by the convex edge. 



BIBL. Turpin, Ann. Sc. Nat. 2. vi. 5 ; 

 Dyer, Qu. Mic. Jn. 1872, 288 ; Quekett, Tr. 

 Mic. Soc. new ser. i. 20 ; Gulliver, Sci. 

 Gossip, 1873 ; Ann. N. H. 1865 ; Qu. Mic. 



Jn. 1866, 1869, 1873; M. M. Jn. x. 259' 

 xviii. 143 ; Lankester, Q. M. J. 1863, 243 '> 

 Urban, Bot. Zeit. 1873, 266; Sanio, Monatsb. 

 Berl. Ak. 1857; Hanstein, ibid. 1859; 

 Holzner, Flora, 1864; Hilgers, Pringsheim's 

 Jahrb. vi. 1867 ; Rosauoff, Bot. Zeit. 1867 ; 

 Solms-Laubach, ib. 1874; Pfitzer, Flora. 

 1872 ; Sachs, Bot. 66. 



RAPHIDIOPH'RYS, Archer. A genus 

 of Rhizopoda. 



Char. Bodies green, spherical, aggregate, 

 surrounded by a common investment of 

 cloudy buff-coloured sarcode, containing 

 slender, hyaline, circular, siliceous spicula. 

 Pseudopodia arising from the sarcode 

 between the spicula, long, straight, and very 

 thin ; they never coalesce. 



BIBL. Archer, Freshw. Rhiz.. Qu. Mic. Jn. 

 1869, 1871. 



RAPHID'IUM, Ktz. A genus of Uni- 

 cellular Algse. Cells fusiform or cylindrical, 

 acuminate, straight or slightly curved, with 

 green cell-contents. The species are those 

 of Ankistrodesmus, Closterium, Micrasterias, 

 and Scenedesmus of other authors. 



Rabenhorst regards our Closteritim Griff. 

 (PL 14. figs. 57, 58) as It. aticulare. 

 BIBL. Rabenht. FL Eur. Alg. iii. 44. 

 RAPHIG'NATHUS, Duges. A genus 

 of Acarina, family Trombidina. 



Char. Palpi long, with an indistinct 

 claw ; mandibles represented by two short 

 setae inserted upon a fleshy bulb, concealed 

 by a broad labium ; body entire : coxae 

 contiguous ; legs but little attenuated at the 

 ends, anterior longest, last joint longer than 

 the others. 



R. ruberrimus (PL 6. fig. 35 a, labium with 

 mandibles and a palp ; b, a mandible). 

 Body oval, slightly depressed, smooth, and 

 almost free from hairs, rostrum forming a 

 conical process; eyes two, dark red, one on 

 each side at the anterior part of the body ; 

 labium triangular, concave ; setae accom- 

 panied by a more slender hair-like process ; 

 pal pi large, inflated, clawof the 4th jointvery 

 short. Found under stones and on plants. 

 JR. hispidus. Form, that of the preceding ; 

 body velvety, with two posterior papillae. 

 BIBL. Duges, Ann. Sc. Nat. 2. i. 22, ii. 

 55 ; Gervais, Walckenaer's Apter. iii. 172 ; 

 Murray, EC. Ent. 114. 



RAT'TULUS, Lamarck. A genus of 

 Rotatoria, of the family Hydatinaea. 



Char. Eyes two, frontal; tail-like foot 

 simply styfiform ; neither cirri nor fins pre- 

 sent. Teeth indistinct. 



R. lunaris (PL 44. fig. 22). Eyes distant 



