TROCHAMMINA. 



[ 784 ] 



TRYPANOSOMA. 



contrasts well with the brilliantly mottled 

 skin. 



BiBL. Bell, British Reptiles. 



TROCHAM'MINA, Parker and Jones.— 

 A variable geuiis of Arenaceous Foramini- 

 fera, very near Lituola ; shell opaque, sandy, 

 smooth ; moniliform, serpentine, folded, 

 discoidal, or subnautUoid and rotalioid ; 

 segmentation mostly obsolete except in the 

 last. Very many species or varieties, recent 

 and fossil. The discoidal forms constitute 

 Reuss's Ammodiscus. Tr. incerta, PI. 28. 

 fig. 14. 



BiBL. Parker and Jones, Q. J, Geol. Soc, 

 xvi. 304 ; Ann. N. H. 4. iv. 386 ; Carpenter, 

 For. 141. 



TROOHIL'IA, Dnj.— A genus of Hypo- 

 trichous Infusoria, family Ervilina. 



Char. Body irregularly oval, narrower in 

 front, where there are some ciHa ; carapace 

 obliquely furrowed, slightly twisted, and 

 terminated behind by a moveable pedicle. 



T. sigmoides (PI. 32. fig. 13) ; fig. 12 re- 

 presents the animal undergoing transverse 

 division ; marine. Two otlier species. 



TROMBIDI'NA.— A family of Acarina. 



Char. Palpi vAth the last joint obtuse, 

 the last but one unguicidate, the second 

 very large ; legs for walking, with two 

 claAvs ; eyes usually latero-anterior. 



Principal genera : Anystis, Cheyletus, Me- 

 gamerus, Pachygnathus, Haphignathxis , 

 Rhyticholophus, Smaris, Tetranychits, and 

 Tromhidium. 



TROMBIDTUM, Latr.— A genus of 

 Trombidina (Arachnida). 



Char. Palpi large, free ; mandibles un- 

 guiculate ; body turgid, bearing the four 

 posterior legs, and an anterior narroAv 

 moveable prominence, upon which the eyes, 

 the four anterior legs, and the mouth are 

 situated ; anterior legs longest ; legs seven- 

 jointed. 



The species are nimierous, and not well 

 characterized. 



T. phalangii (PI. (J. fig. 37). Body sub- 

 triangular, angles obtuse ; of a velvety ap- 

 pearance, from the presence of numerous 

 plumose hairs ; eyes two, placed upon auri- 

 cular appendages. 



An external parasite of Phalangium (the 

 harvest-spider) and insects, at least in its 

 early hexapodous stage. 



T. eliDtgatum. Crimson ; eyes approxi- 

 mate. Found under stones. 



T. cinereum (PI. 6. fig. 40) (Rhynchoh- 

 phits ciner., l^ug.). Body with brown and 

 greyish-white spots ; hairs spathidate ; eyes 



two on each side. Length 1-12". Found 

 in ditches amongst plonts and stones. 



T. autumnale (PI. 6. fig. 38) (Leptus au- 

 tumn.). The harvest-bug. This well- 

 known arachnidan insinuates itself into the 

 human skin in autumn, causing troublesome 

 irritation. It is found ou plants and the 

 stubble of corn-fields, and may easily be 

 caught by tying a white pocket-hauclker- 

 chief around the legs, and walking through 

 stubble-fields. The young form with six 

 legs is most frequent^ met with. 



T. aurantiacum, on the black \iQ?m- Aphis. 

 Other species. 



T. {Atoma) parasiticum, on the house-fly. 

 Other species. 



BiBL. Duges, Ann. Sc. N. 2. i. 36 ; Ger- 

 vais, Walck. Apteres, iii. 178 ; Johnston, 

 Tr. Berwick. Nat. Club, 1847, 221 ; Koch, 

 Deutschl. Crust. Myriap. i>;c. : Murray, Ee. 

 Ent. 128. 



TRUNCATULI'NA, D'Orb.— A sub- 

 genus of Planorhtdina. Shell discoidal, 

 plano-convex, thick or thin, lobular or neat, 

 adherent by the flat face ; orifice slit-like, 

 slightly apparent above and continued be- 

 neath, along tlie line of suture, as far as the 

 second or third chambers. 



Man)' recent and fossil species. PI. (Tr.) 

 lohatula (PL 24. fig. 9); very common, 

 attached to sea-weeds. 



BiBL. Williamson, Rec. For. 60 ; Car- 

 penter, Foram. 207 ; Parker & Jones, Phil. 

 Trans, civ. 381. 



TRYBLIONEL'LA, Smith.— A genus of 

 Diatomacese. 



Char, Frustules free, linear or elliptical 

 in front view ; valves plane, with parallel 

 transverse (tubular ?) strife, and submarginal 

 or obsolete alfe. 



In some a median line is present, in 

 others not. The, alfe are not marginal, as 

 in Surirella, but arise from the surface of 

 the valves, as shown by the diagram of a 

 transverse section in PI. 17. fig. 32. 



T.sctdellum (PL 17. fig. 30). Valves 

 elliptical, with a median longitudinal line; 

 alae very short ; striae faint ; marine ; length 

 1-140". 



T. gracilis (PL 17. fig. 31). Frustules 

 linear, narrowed at the ends ; valves linear, 

 acuminate, strite coarse ; alje distinct ; fresh 

 and brackish water ; length 1-200". 



Four other species. 



BiBL. Smith, Brit. Diatom, i. 35; Rabenh. 

 Alg. i. 347. 



TRYPANOSO'MA, Gruby.— A genus 

 of Flagellate Infusoria. Free, compressed ; 



