296 



FRESH-WATER BIOLOGY 



195 (196) Animals growing in clusters, attached or free-floating, enclosed in 

 a mucilaginous jelly. Zooids attached to a branching stalk, 

 each secreting a jelly-like tube which may remain distinct 

 or fuse with its neighbor forming a jelly mass. Zooids 

 similar in anatomy to Vorticella. Usually green. 



Ophrydium Ehrenberg. 

 Representative species. •. . Ophrydium eichhornii Ehrenberg 1838. 



Bodies very plastic, finely striate transversely. Clusters hemispherical, of 

 closely approximated individuals. Some colonies may include as many as one 

 hundred zooids, although this large size is uncommon. 



Division of the body has been observed to take place in a transverse direction, 

 which is a rare occurrence in this family. 



The anterior portion swims away and settles down to form a new colony, or 

 probably conjugates with some fi.\ed zooid. Length of expanded zooids 250 to 

 500 n. Fresh water. 



Fig. 546. Ophrydium eichhornii 



a\ contractile vacuole; 

 (After Kent.) 



I, macronucleus. X $o. 



' )6 (195) 



197 (194) 



198 (205) 



199 (202) 



200 (201) 



Animals solitary; similar in other respects to Ophrydium. 



Ophridinopsis Kent. 



Lorica chitinous 198 



Lorica not decumbent • 199 



Lorica sessile 200 



Lorica with a hinge-like valve that closes the opening when the 

 body retracts. Lorica elongate, subcylindrical. Body 

 elongate with ciliary system as Vorticella. 



Thuricola Kent. 



Representative species Thuricola valvata Wright 1858. 



Lorica four or five times as long as broad, with the valve at some dis- 

 tance from the aperture. Length of lorica i20m- Fresh water; also 

 reported from salt water. In Thuricolopsis Stokes the lorica is provided 

 with a support for the valve. Otherwise as Thuricola. 



Fig. 547. Thuricola valvata. X 150. (After Kent.) 



201 (200) Lorica without a valve. 

 Representative species. 



Vaginicola Claparede and Lachmann. 

 Vaginicola leptosoma Stokes 1885. 



Lorica broadly vasiform, twice as long as broad, inflated posteriorly. Zooid 

 elongate, projecting one-third its length beyond the lorica. Peristome twice as 

 broad as the body. Surface transversely striate. Length of lorica 120 /x. 

 Pond water. 



Fig. 548. Vaginicola leptosoma. ct, contractile vacuole. X no. (After Stokes.) 



202 (199) Lorica with a pedicel 203 



