shape; M.L. adj. leptomitiformis Leptomi- tus-like. Trichomes, 1.0 to 2.5 microns in diameter, of uniform width. Segments 4.0 to 8.0 mi- crons in length; segmentation observable only after removal of sulfur globules. Ter- minal cells are usually rounded. Habitat : Found in fresh-water and marine environments containing hydrogen sulfide. condition, they are of uniform width; bulg- ing of the sides occurs under unfavorable conditions. Trichomes clearly segmented. Segments 5.0 to 13.0 (average, 8.5) microns in length. Terminal cells are rounded or tapered. Habitat : Apparently restricted to marine environments containing hydrogen sulfide. Frequently found on decaying marine algae. 4. Beggiatoa minima Winogradsky, 1888. (Beitr. z. Morph. u. Physiol, d. Bac- terien, I. Schwefelbacterien, 1888, 25.) mi'ni.ma. L. sup. adj. minimus least, smallest. Trichomes, less than 1 micron in diame- ter, of uniform width, normally appearing unsegmented. Segments about 1 micron in length. Habitat: Found in fresh-water and ma- rine environments containing hydrogen sulfide. 5. Beggiatoa gigantea Klas, 1937. (Klas, Arch. f. Mikrobiol., 8, 1937, 318; includes the large forms of Beggiatoa mirahilis Cohn, Hedwigia, 4, 1865, 81.) gi.gan'te.a. Gr. adj. giganteus gigantic. Trichomes 26.4 to 55.0 (average 35 to 40) microns in diameter. Klas {op. cit., 1937, 318) gives 26.4 to 42.9 microns as the dimen- sions, which would exclude the largest forms of Beggiatoa mirahilis described by Hinze (Ber. d. deut. bot. Ges., 19, 1901, 369). Since the proposal of a separate species for such organisms appears at present unjustified, the maximum diameter has here been in- creased. When the trichomes are in a healthy 6. Beggiatoa mirahilis Cohn, 1865, emend. Klas, 1937. (Cohn, Hedwigia, 4, 1865, 81; Klas, Arch. f. Mikrobiol., 8, 1937, 318.) mi.ra'bi.lis. L. adj. mirahilis marvelous. Trichomes 15.0 to 21.5 (average, 17.0) microns in diameter. The so-defined species does not overlap with Beggiatoa gigantea according to Klas {loc. cit.). When the tri- chomes are in a healthy condition, they are of uniform width; an unfavorable environ- ment induces bulging of the sides. Segments 5.0 to 13.0 (average, 8.5) microns in length; segmentation usually observable without special treatment. Terminal cells are rounded or tapered, sometimes bent. Comment: Uphof (Arch. f. Hydrobiol., 18, 1927, 83) has recognized a species, Beg- giatoa maxima, which, on account of its di- ameter (10 to 20 microns) , falls partly within the range of Beggiatoa mirahilis and partly within Beggiatoa arachnoidea. Since it was found in a fresh-water environment, the habitat of Beggiatoa mirahilis may not be restricted to marine media. Habitat: Apparently restricted to marine environments containing hydrogen sulfide. Common on decaying marine algae. Genus II. Thiospirillopsis Uphof, 1927. (Arch. f. Hydrobiol., 18, 1927, 81.) Thi.o.spi.ril.lop'sis. M.L. neut.n. Thiospirillum a genus of bacteria; Gr. noun opsis ap- pearance; M.L. fem.n. Thiospirillopsis that which has the appearance of Thiospirillum. Colorless sulfur bacteria occurring in segmented and spirallj^ wound trichomes. Exhibit a creeping motility combined with rotation so that the trichomes move forward with a corkscrew-like motion. The tips may oscillate. Resembles Spirulina among the Oscilla- toriaceae. The type species is Thiospirillopsis floridana Uphof. 1. Thiospirillopsis floridana Uphof, 1927. (Arch. f. Hydrobiol., 18, 1927, 83.) flo.ri.da'na. M.L. adj. fioridanus per- taining to Florida.
