818 



SYSTEMATIC HISTOEY OF THE INFUSORIA. 



stream forth, and two elongated cilia 

 become visible at their hyaline smaller 

 end. Their movement lasts for a very 

 short period ; they settle do\^ai, and 

 quickly equal or surpass in size the 

 mother-cell." If this description be cor- 

 rect, it will add an important fact in sup- 

 port of their vegetable nature. Professor 

 Smith makes the following diagnostic 

 remarks upon this species : — " The only 

 species with M^hich this form can be con- 

 founded is 31. suhJlexUis ; but M. variam 

 has the extremities of its frustules closely 

 applied and partially truncate ; those of 

 M. suhJlexiUs are often more or less 

 separated by a mucous cushion, and di- 

 stinctly convex. . . . M. suhflexilis, when 

 in abundance, appears as a dark-gTeen 

 iridescent mass. 31. varians always pre- 

 sents a rich golden-yellow or chestnut 

 to the eye. The geminate arrangement 

 of the frustules is conspicuous in 31. snb- 

 JlexiUs, and indistinct in 31. varians.^'' 

 SBD. ii. p. 58. The fossil frustules of 

 this species constitute the gTeater part 

 of the earthy deposits of white powder 

 used in polishins; silver plate, (iv. 32 ; 

 IX.* 131 J XY.320 



3 * Fnistulcs ci/lindrical , hlsulcate, ivith 

 rounded junction-margins. 



M. disfans (E., K.). — Slender; joints 

 cylindrical, smooth or indistinctly pmic- 

 tated, ^dth two distant, delicate, ring- 

 like fuiTows, all closely connected ; disc 

 plane. KB. p. 54, pi 2. f. 12. Fresh 

 ■water. Europe, Asia, Australia, Africa, 

 and America. Fossil, Bilin, &c. Diam. 

 1-3456" to 1-8C4". Joints once to t^^dce 

 as long as broad. 



M. nivalis (S.). — .Joints subcylindrical ; 

 valves subhemispherical, distinctly cel- 

 lulate ; extremities more or less trimcate ; 

 disc dotted. SBD. ii. p. 68, pi. 53. f. 

 336. = Coscinodiscus minor, SBD. i. p. 23, 

 pi. 3. f. 36. Fresh water in iVlpine di- 

 stricts. Britain. According to Professor 

 Smith, this form hardly differs from 

 M. distatis, except in the greater di- 

 stinctness of the cellules, and may not 

 be distinct. 



M. orichalcea (Mortens, K.). — Slender; 

 joints obscurely punctated, mostly longer 

 than broad, closely binately conjoined, 

 with sliglitly crenidate ends and tw^o 

 median furrows ; disc plane. KB. p. 54, 

 t. 2. f. 14. = GalUonclla aurichalcea, Ehr 

 Inf. Fresh water. Common. Europe, 

 Asia, Africa, and America. Younger 

 joints two or three times as long as 

 broad ; older ones shorter. This species 

 differs from 31. Italica merely in its 



more obscure crenations and apparently 

 smooth disc; and perhaps Professor 

 Smith rightly united them. Its Hat and 

 closely comiected ends distingiush it 

 from 31. varians. (v. 65 ; mttl. 33.) 



M. Italica (E., K.). — Slender ; joints 

 cylindrical, longer than broad, with den- 

 ticulated ends and two median furrows ; 

 disc with striated border. KB. p. 55, 

 pi. 2. f 6. = GallioneUa Italica, Ehr. ; G. 

 crenata, EM. many figiu-es ; G. crenn- 

 lata, EA. pi. 2. 1. f. 14 ; 3Ielosira ori- 

 chalcea, llalfs, Annals, xii ; Aidacosira 

 cremdata, Thwaites; Orfhosira orichalcea, 

 SBD. ii. p. 61, pL 53. f. 337. Fresh 

 water. Europe, Asia, Australia, Africa, 

 and America, (xi.29, xy.33.) (3. Binde- 

 rana, Kiitz., more slender; joints four 

 to eight times as long as broad, often 

 inflated; disc striated, KB. pi. 2. f. 1. 

 Hamburgh. Mr. Thwaites describes the 

 sporangium as orbicular, wdth its axis of 

 elongation at right angles to that of the 

 frustide from which it originated; but 

 Professor Smith's experience did not en- 

 able him fidly to conhrm Mr. Thwaites's 

 observations. 



M. coarctata (E.). — Joints smooth. Its 

 habit is that of 31. varians, but its disc 

 is not striated. E A. pi. 3. 5. f. 9. Mexico, 

 (xi. 20 & 27.) Kiitzing miites this form 

 with M. orichalcea. 



M. Roseana (Rab.). — Joints longer 

 than broad, w4th two broad constrictions 

 and dentated truncate junction-margins; 

 disc with radiating stripe and three or 

 more central dots. Rab D. p. 13, t. 10. 

 = Orthosira spinosa, SBD. ii. p. 61, pi. 

 61. f. 386. Europe. Caves, in moss, on 

 trees, kc. ; probably conmion. Much as 

 they diftier in appearance, the late Pro- 

 fessor Gregory considered that he had 

 traced the Liparogyra spiralis into this 

 species; and certainly the two forms 

 are almost invariably found together. 

 (V. 67.) 



M. IcBvis (E.) = GallioneUa Icevis, EM. 

 pis. 9, 14 tfe 33. Ehrenberg gives up- 

 wards of fifty habitats in Australia, Asia, 

 Africa, and America. His figures of this 

 species differ considerably from each 

 other, and, in the absence of description, 

 render it difficult to form any idea of the 

 specific characters. Ehrenberg (/. c. p. 

 118) says it is allied to Stqyhanodisciis 

 Epidendron, and we strongly suspect 

 that both these forms ought to be miited 

 to 31. Roseana. 



M. piiJeata (E., K.). — Joints shorter 

 than broad, smooth, with two finely 

 punctated, widely separated sutures. 

 Junction-portions convex, smooth, often 



