58 CLASS I. 



Cothurnia EHRENB. Animal solitary, sessile, with urceolar 

 lorica, pedunculate. 



(According to DUJARDIN not sufficiently distinct from the preceding genus.) 



Phalanx II. Body (in the first period of life) pediculated. 

 A. Naked. 



Vorticella MUELL. (exclusive of several species). Animal cam- 

 panulate, with a flexible pedicle spirally contractile. 



These animals adhere to water-plants, water-insects, small Crustacea (Cyclops), 

 &c. At a certain period they part from the stem, and then, as freely 

 moving forms, are provided with cilia near the posterior extremity by 

 means of which they move forward, whilst the coronet of cilia at the edge 

 of the opening is entirely retracted. 



a) with simple pedicle. 



Vorticella EHRENB. Sp. Vorticella convallaria L., Vorticella nebulifera 

 EHRENB., EOESEL, Ins. in. Suppl. figs, i, 4-7, MUELL. In/us. Tab. XLV. 

 fig. T, EHRENB. Tab. xxv. fig. i. A very similar species occurs in artificial 

 infusions, which on contraction exhibits transverse rings, and which 

 EHRENBERQ distinguishes as Vorlic. convaUaria. 



b) with branching pedicle. 



Carchesium EHRENB. Sp. Vorticella polypina, L., MUELL. Infus. Tab. 

 XLVI. figs. 7-9 ; EHRENB. Infus. Tab. xxvi. fig. 5 ; polypes a bouquet 

 TKEMBLEY ; resembles an umbelliferous shrub, of about one line in size, in 

 fresh and also in sea-water ; see BASTER, Natuurk. Uitspanningen I, Tab. 

 in. fig. i, C ; SLABBER, Natuurk. Verlustigingen 1778. Tab. v. fig. 2. 



[Zoothamnium 1 EHRENB. 



Sp. Zoothamnium arbuscula EHRENB., Infusionsth. Tab. xxix. fig. 2.] 



f 1 The stem of spirally flexible Vorticellines consists of a wall and an internal 

 canal containing a thread, or streak, which does not exactly fill it. When a stem or 

 branch divides, the structure of the divided parts is not exactly the same in Carchesium 

 and Zoothamnium. In CarcJiesium the canal and streak of a branch have no connexion 

 with the corresponding parts of the stem on which it stands. After each fission 

 one only of the fission-progeny occupies the apex of the already existing stem, and 

 continues to prolong it by secretion of new matter, the canal and the thread suffering 

 no breach of continuity. The other individual secretes at first a short portion of stem 

 which is quite solid, and is in connexion with the outer wall only of the stem pre- 

 viously existing. It is after this commencement that a new canal and a new streak 

 begin to be seen. The same occurs at every subsequent division : the individual at 

 the apex has the canal and streak of its stem in continuity with the similar parts 



