T^NIOPTERIS. 



[ 628 ] 



TARDIGRADA. 



the figure. The thick brittle coat of the 

 ovum exhibits an appearance of radiating 

 fibres, and when broken the fractures are 

 radiant. When the middle of the outer 

 sm-face of the brittle envelope is brought 

 into focus, it presents a tolerably regular 

 appearance, as if composed of cells; this 

 arises, however, from the extremities of the 

 fibres being brought into focus. 



The spermatozoa are readily found, simply 

 by picking any joint containing ova to pieces 

 with needles. 



The old genera Coenurus, Cysticercus, and 

 Echinococcus represent the larval or nurse- 

 forms of Tcenia. 



See Entozoa. 



Tcenia lata = Bothriocephalus latus. 



BiBL. See that of Entozoa and Both- 

 riocephalus. 



T^NIOPTERIS, Hook.— A genus of 

 Taenitidese (Polypodseous Ferns). Exotic. 



T^NITIDE^.— A subtribe of Polypo- 

 dfeous Ferns, without an indusium, including 

 the following genera : — 



I. Pleurogramma. Sori contiguous 

 on each side of the rib, parallel, linear, and 

 continuous. 



II. PoLYT^NiUM. Sori very long, con- 

 tinuous or interrupted, two to four between 

 the rib and the margin, linear, immersed, 

 parallel, occupying longitudinal veins. Veins 

 anastomosing. 



III. T^NioPTERis. Sori submarginal, 

 linear, elongated, continuous, deeply im- 

 bedded. Veins simple, scarcely anastomo- 

 sing. 



IV. T^NiTis. Sori submarginal in the 

 middle of the disk of the leaf, linear, elon- 

 gated and continuous. Veins anastomosing 

 more or less regularly into meshes. 



V. Jenkinsia. Sori linear, elongated, 

 continuous. Veins anastomosing into more 

 or less regular meshes, with fi-ee venules. 



TiENITIS, Sw.— The typical genus of 

 Tsenitideee (Polypodaeous Ferns). Exotic. 



TALC. See'MiCA. 



TA0NL4, J. Ag. — A genus of Dictyotaceae 

 (Fucoid Algae), containing one rare British 

 species, T. atomaria, which has a flat, mem- 

 branous, fan-shaped, deeply cleft frond, 

 3 to 12" high, of brownish olive colour; 

 marked on both faces at intervals of 1-4 to 

 1-2", with concentric wavy lines, formed by 

 rather crowded dark brown "spores," the 

 interspaces being dotted over with scattered 

 spores. The disk of attachment is covered 

 with woolly filaments. 



Thuret has recently shown that the Dic- 



tyotaceae should be separated from the Fu- 

 caceae, and stand between them and the 

 Florideae, since he has found not only that 

 their spores are analogous to the concepta- 

 cular spores of the latter, and do not pro- 

 duce ciliated zoospores, but that also they 

 produce tetraspores, and what appear to be 

 antheridia (Dictyota) in different individuals. 



BiBL. Harvey, Brit. Mar. Alg. p. 38. 

 pi. 7 A; Thuret, Ann. des Sc. nat. 4 ser. 

 iii. p. 7- 



TAPHROCAMPA, Gosse.— A genus of 

 Rotatoria, of the family Hydatinaea. 



Char. Rotatory organs absent ; body fusi- 

 form, annulose, tail forked, gizzard oval. 



T. annulosa. Aquatic; length 1-110". 



BiBL. Gosse, Ann. Nat. Hist. 1851. viii. 

 199. 



TAPIOCA. — A very pure fecula prepared 

 from the finer particles of the starch of the 

 Mandioc or Cassava plant (PL 36. fig. 14). 

 The starch-granules of tapioca of the shops 

 appear to have undergone the action of 

 heat, which disguises the characters. See 

 Starch. 



TARDIGRADA (Water-bears).— A family 

 of Arachnida, of the order Colopoda. 



Char. As this is the only family, the cha- 

 racters are those of the order (Arachnida, 

 p. 57). 



These microscopic animals are found in 

 stagnant fi-esh water, amongst water-plants, 

 in patches of w^et moss, in the gutters of 

 houses, &c. 



Body soft, cylindrical, or elongate-oval in 

 outline, with four transverse furrows, or in- 

 distinct segments, and a fifth anterior, corre- 

 sponding to a head, short, conical, retractile, 

 and with indications of two or three seg- 

 ments ; sometimes dilated at the end to form 

 a sucker, or furnished with unequal, short, 

 palp-like processes. Eyes two. 



The oral organs are represented by a tu- 

 bular rostrum, through the sides of which, 

 from without inwards, two calcareous styles 

 or mandibles pass, and serve to wound the 

 animals forming their prey. At the base of 

 the rostrum is a gizzard with radiating mus- 

 cular fibres, in Macrobiotus enclosing a kind 

 of framework consisting of six parallel jointed 

 cylinders. 



The alimentary canal is straight, and fur- 

 nished with lateral caecal appendages. The 

 ovary is a simple sac, behind which is situ- 

 ateda seminal vesicle containing spermatozoa, 

 both opening into a cloaca. But few eggs 

 are produced at a time; they are either 

 smooth, rugous, or studded with points, and 



