698 



DESCRIPTION or ENGBATING8. 



PLATE XXI {continued.) 



Figs 23. Fleuroncma crassa 



24. a. b. Trachelius lamella 



25. Uronema marina 



26. Dilejitus folium 



27. Sparthidium hyalinura 



28 and 29. Opalina naidura 



30. a. b. c. Coccudina polypoda 



31. a. b. c Halteria a^ranilinella 



32. Losophyllum meleagi-is 



33. Pauophrys chrysalis 



2. A 



PLATE XXII. 



The figures in this plate are from Mr. Stein's papers in the "Arehiv. fur 

 Natiirgcschichte," for 1849 ; and are magnified 300 linear measure. 



igs. 1. Vorticella microstoma. A full grown specimen cxliiliting the contractile 

 vesical, the alimentai-y tule, and ciliated front and mouth, also the 

 growth of a hud from the hase. 



specimen with the |)Osterior circlet of cilia, prepared to detach itself 

 from its stalk. The contractile vesicle and band-like nucleus (testes, 

 Ehr.) are well seen. 



3. An individual undergoing self-division; the nucleus has already divided; a 

 new frontal wreath is in process of formation in the semi-lunar spaces 

 at the anterior angle of each half, 



4. A specimen in which self-division has been completed. One newly de- 

 veloped heing has its posterior cilia produced, — its anterior wreath at 

 the same time included, ready to detach itself. 



5. a. b. c. d. e, ; figs. a. b- c d. illustrate the progi-ess of the cncysting-process. 

 The enclosing tunic is v\ ell shown in fig. d, and also in fig. e. ; in the 

 latter this tunic is supposed to have been ruptured by pressure, and the 

 encysted animal to have protruded itself, showing it to have not lost its 

 original condition in its larva-like state. 



6. This group illustrates the many transition -forms between the simple cam- 

 panulate organisms, springing apparently from the granular matrix 

 to which they are attached, and the larger and unmistakeable forms of 

 Vorticella. 



7. 8 and 9. Eepresent the encysted examples of Vorticella, and the gradual 

 obliteration of special organs by the advance of the process; in fig. ^J all 

 traces of organs being lost. 



10. Vagiiiicola ciystallina. A large specimen, undergoing self-division. 



11. An old and young specimen in the same case : the latter with its " front" 

 included, whilst the posterior wreath of cilia is developed to enable it 

 to swim about. It also represents the first stage in the encysting 

 process. 



12. 13, 14 and 15. Various degrees of development of the Acineta-body of the 

 Vasfinicola; the first stage following the encysting process, is seen 

 in fig- 12. 



Epistylis nutans. Two large individuals supported on a stem. The one to 

 the left with its ciliated lip protruded : that to the right, ^^ith it included. 

 The large a-sophageal cavity is \\ ell seen, with its abrupt contraction 

 into a linear narrow intestine. The nucleus is seen lying transversely 

 across the oesophagus, and the contractile vesicle below. 



The Acineta-body of the Epistylis. The wavy outline indicates the con- 

 tractions taking place in the integument 



An Acineta-body of Ej.istylis. with the outstretched ciliary fibres or pro- 

 cesses. Two nuclei are visible^ and a large contractile vesicle. 



Another such body, with its surface much conti-acted, and its contained 

 substance wasted by the developvi.cnt of embryonic nuclei. 



16. 



17 



18. 



19, 



