OF THE OPHEYDINA. 



603 



Genus COTHURXIA (XXX. 12-16).— Lorica (sheath) urceolate, and sup- 

 ported on a rigid pedicle. A wreath of cilia is placed upon the flat frontal 

 region ; and the mouth, with the anal opening, lies on one side, within the 

 vestibulum. The body is contractile, and can withdraw itself within the 

 stiff sheath ; fission longitudinal. 



It is unnecessary to enlarge on the structural details of this genus, inas- 

 much as they are in aU particulars like those of VaginicoJa, from which it is 

 separated only by its sheath being stalked. 



aspect. The two angles in front are ex- 

 tended upwards and outwards, but at the 

 same time curved inwards at their ex- 



CoTHUBNiA imherhis (Vorticella folli- 

 culata, M.). — Pedicle mostly bent and 

 much shoi-ter than the sheath, which 

 has, when old, a yellowish colour. 

 Sheath tubular, narrowed anteriorly, 

 without an everted margin. Even when 

 outsti-etched, the animal extends little 

 beyond the mouth of the sheath; its 

 periston! is scarcely appreciably thick- 

 ened, and not everted at all ; it is evi- 

 dently ciliated. The disc of the simple 

 rotary organ is level on its surface, and 

 scarcely rises above the sheath. Diges- 

 tive tube long and narrow, extends be- 

 yond the centre of the body, and near 

 its commencement has fi-om 3 to 4 long 

 cilia. Near to it, on one side, is a round 

 contractile vesicle, and on the other a 

 short, band-like nucleus, almost straight 

 or slightly reniform in figure. Longi- 

 tudinal fission frequently observed, and 

 sufficiently often the process of gemma- 

 tion at the base. Length of sheath 1-288" 

 to 1-240". 



Ehrenberg remarks, " This animalcule 

 had often 'swallowed gTcen Monads, and 

 yet accepted indigo. Trichoduui vorax 

 is the enemy of this species." Upon 

 Cyclops quadricornis. Length of sheath 

 1-280". 



C maritima. — Pedicle much shorter 

 than the hyaline sheath; body hyaline 

 and whitish. Length of sheath 1-570''. 



C. maritima is very closely aUied to 

 VaginicoJa crystallina : not the least dif- 

 ference between the animals themselves 

 is perceptible, and the figure of the 

 sheath is the same, — the only essential 

 difterence being that in the Cothurnia 

 the sheath is supported on a thin, solid 

 stem, 1-48" to 1-36" in diameter and 

 of a length equal to its own. 



C. Havniemis. — Pedicle much longer 

 than the hvaline sheath ; body whitish, 

 Leng-th without stalk 1-280". 

 ^ C. Sieholdii (Stein) (xxx. 13, 14).— 

 Sheath stalked ; stalk short, thick, colour- 

 less, transversely and deeply vviinkled, 

 and thickened at its junction with the 

 sheath. The last is campanulate, strongly 

 compressed in fi-ont, dilated and bellied 

 out posteriorly, especially on the dorsal 



tremities as two horns. The waUs of 

 the sheath are at first soft, colourless, 

 and hyaline, but subsequently become 

 yellow and leathery, and at last of a 

 more or less deep rusty brown colour, 

 and of a corneous consistence. The 

 colomless and, with reference to the 

 sheath, small contained animal is cylin- 

 drical in figure, contracted behind,^ and 

 ver}^ similar to that of Vayinicola crystal- 

 Una. Its periston! forms an annidar 

 thick border, and is beset with few cilia. 

 The digestive tube, which extends to 

 nearly the centre of the body, has close 

 to it the contractile vesicle, and a little 

 fm-ther behind, the thick, short band-like 

 and semicircular nucleus, visible without 

 the use of chemical reagents. Multipli- 

 cation takes place by longitudinal fission. 

 Length of largest sheaths 1-190". On 

 the limbs and other parts of Eutomos- 

 traca ; very abundantly. 



C. Astaci (Stein) (xxx. 15). — Sheath 

 supported on a short, w!'inkled, thick 

 pedicle; having itself a tubular figure, 

 rather contracted at the middle, and its 

 border widened and everted, whilst its 

 posterior half is slightly ventricose and 

 rounded at its extremity. Its consist- 

 ence is leathery or hon!y when old ; it 

 is transparent and of a pale yellow colour, 

 but never a rusty browTi. When fully 

 outstretched, the animal protrudes a con- 

 siderable distance beyond the mouth of 

 the sheath, differing in this respect, as 

 well as by its thick annidar peristom and 

 its cylindrical outline, from Cothurnia 

 imherbis. The digestive tube attains the 

 middle of the animal, is very narrow, 

 and has both the contractile vesicle 

 and the short band-like nucleus placed 

 near its tennination. Fission is longi- 

 tudinal. 



Old specimens attain a height of 

 1-288", and a width of 1-600". Also 

 found on Entomostraca. It is very closely 

 allied to C. imberhis ; but, besides the 

 differences noted between the animal- 

 cules, the stem of the latter is relatively 



