820 



syste;matic history of the infusoria. 



and fossil, (ix. 131 and xi. 20.) This 

 species, which varies considerably in 

 size, is well marked by its short, slightly 

 angular joints, and its transverse scidp- 

 ture-like marks on each side of the su- 

 ture. Margin of disc often denticulate. 

 Diam. 1-860" to 1-600". 



M. coronata (E., K.). — 31. sulcata in 

 habit; joints cylindrical, striated; disc 

 smooth, slightly convex, with a crenated 

 margin and a circlet of pearl-like gra- 

 nides within. KSA. p. 31. = GaJlionella 

 coronata, EM. pi. 38. 22. F. 5. Marine. 

 Asia, Africa, Patagonia. Diam. 1-864". 

 It differs from M. sulcata only in the 

 more distinct crenations of the disc and 

 the circlet of dots. 



M. iilana (E., K.).— Habit of 31. sul- 

 cata ; but disc plane, smooth, and neither 

 radiated nor granular. KSA. p. 31.= 

 GallioneUa lilana, ERBA. 1845. Fossil. 

 Patagonia. D. 1-1152". This form may 

 possibly be 31. sulcata, with its markings 

 destroyed by igneous action. 



M. Hetrurica (K.). — Small ; joints 

 cylindrical, smooth, twice as long as 

 broad, vnt\\ finely denticulated junction- 

 margins ; disc convex, marked with 

 dotted ravs. KB. p. 55, pi. 2. f. 6. Fossil. 

 San Fiore. Diam. 1-3600" to 1-800". 



M. f/ramdata (E.). — Joints longer than 

 broad, Tvnth horizontal punctated lines 

 on each side of the median suture, and 

 denticulated junction-margins ; disc with 

 a series of marginal puncta. = GaUioneUa 

 granulata, EA. p. 123; ]M. manv fisures ; 

 G. tenerrima, EM. pi. 39. f. 50 ; Ortlio- 

 sira punctata, SBD. ii. p. 62, pi. 53. f. 

 339. Fresh water. Ehrenberg gives 

 upwards of 50 habitats in Europe, Asia, 

 and America. 



M. /3. maxima. Disc with 31 mar- 

 ginal denticulations, and sti'ongly akin 

 to 31. sulcata. 



M. 3Iarchica (E.). — Resembles 31. 

 granulata ; but the dotted lines are pa- 

 rallel to the suture, and not horizontal. = 

 GaJlionella 3I(n'chica,'EM. several figures; 

 G. procera, EM. pi. 15 a. f. 1. Fresh 

 water. Europe, Asia, Africa, and Ame- 

 rica. 



M. clccussata (E.). — Resembles 31. 

 f/ramdata ; but the dotted lines are dia- 

 gonal and decussating. = GallioneUa de- 

 russata, EM. several figures. Fresh 

 water. Asia, Africa, and America. 

 Kiitzing includes, perhaps correctly, 31. 

 3Iarchica and 31. (jranulata under this 

 species. 



M. lirata (E., K.).— Has the habit of 

 31. granulata, but ^^nth more conspi- 

 cuous lines, disposed like the strings of 



a Ivre. KSA. p. 31.= GallioneUa lirata, 

 EM. pl. 2. 3. f. 33. Fossil. America. 



M. spiralis (E.,K.). — Filaments cm-ved 

 and spiral; joints small, oblique, longer 

 than broad, or equal, loosely punctated 

 in transverse series. KSA. p. 31. = Gal- 

 lioneUa spiralis, EM. pl. 33. 13. f. 3. 

 Fossil. Oregon. Diam. 1-2304". 



M. Americana (Kiitz.). — Frustules in- 

 cluded in a jointed cylindrical tube, 

 separated by dissepiments of the tube, 

 elliptic, with striated margins and a 

 median furrow; disc with radiating 

 styise, convex. KB. pl. 30. f. 69. = Ortho- 

 sira Americana. Diam. 1-660". Appa- 

 rently fm-nished with internal silicious 

 cells. 



M. Dickieii (Thwaites, K.). — Joints 

 mostly longer than broad, smooth or ob- 

 scurely punctated, except by conspicuous 

 dots bordering the sutm-e ; disc obscurely 

 punctate ; sporangia ? fusiform. KSA. 

 p. 889.= OrtJwsira Dickieii, Thwaites, 

 ANH. 2nd series, i. pl. 12; SBD. ii. 

 p. 60, pl. 52. f. 335. Fresh water. Cave 

 near Aberdeen, (xv. 29.) " The fila- 

 ments of this beautiful species consist 

 generally each of from two to four frus- 

 tules, which are hyaline and perfectly 

 smooth ; central cavity filled wath dark 

 red-brown endochrome ; sporangium 

 fusiform, marked with numerous annular 

 constrictions, whose formation is pro- 

 gressive, and which go on increasing 

 until the sporangium is fully developed 

 (xv. 296. 29 B. a filament, the tenninal 

 cells of which have each commenced to 

 develope a sporangium ; and f. 29 c. a 

 mature sporangium). This formation 

 thus occurs : at the commencement of 

 the formation of a sporangium, the endo- 

 chrome, at the same time that it with- 

 draws from the end of the fi'ustule, pro- 

 duces at its centre an additional ring of 

 cell-membrane ; and, this process con- 

 tinuing to take place at certain intervals, 

 each new ring of cell-membrane exceed- 

 ing in diameter those previously formed, 

 produces at length the structure repre- 

 sented in f. 29 c ; or it may be a more 

 correct explanation of the process to say 

 that an entii'e new cell-membrane has 

 been developed by the young sporangiimi 

 at the time each new ring has been 

 formed, and that thus have originated 

 the several chambers into which the ends 

 of the sporangium are divided; fissi- 

 parous division subsequently takes place, 

 and sporangial frustules are developed 

 from each half, as shown in f. 29 d." 

 Professor Smith doubted whether the 

 fusifonn bodies are sporangia, as ^^this 



