SPIROTRICHA, HYPOTRICHA 



679 



marked by a plate and with two ciliary tufts, near the middle of an- 

 terior half; 5-6 caudal cirri; macro nucleus curved band-form; a 

 terminal contractile vacuole; zooxanthellae, but no food vacuole in 

 cytoplasm; marine, on the coral. 



P. tortugensis W. (Fig. 319). Subcircular to ovoid; average indi- 

 viduals 85ju by 75m: ciliary plate 37/1 long, with longer cilia; adoral 

 zone reaches nearly the posterior end; "micro nucleus not clearly 

 differentiated" (Wichterman) ; 5-6 caudal cirri about 13/i long; zoo- 

 xanthellae yellowish brown, about 12/x in diameter, fill the body; 

 found on Eunicea crassa (coral); Tortugas, Florida. 



Fig. 319. a, b, dorsal and ventral views of Paraeuplotes tortugensis in 

 life (Wichterman). avc,,"anterior ventral cilia; cp, ciliary plate; cpc, 

 ciliary plate cilia; cv, contractile vacuole; ds, dorsal swelling; fm, frontal 

 membranellae; om, adoral membranellae; sp, caudal cirri; tc, tufts of 

 cilia; zo, zooxanthellae. X about 470. 



Family 4 Aspidiscidae Claus 



Genus Aspidisca Ehrenberg. Small; ovoid; inflexible; right and 

 dorsal side convex, ventral side flattened; dorsal surface conspicu- 

 ously ridged; adoral zone reduced or rudimentary; 7 frontal-ventrals; 

 5-12 anals; macro nucleus horseshoe-shaped or occasionally in 2 

 rounded parts; contractile vacuole posterior; fresh or salt water. 

 Numerous species. 



A. lynceus E. (Figs. 54; 318, h). 30-50^ long; fresh water. Division 

 was studied by Summers (1935). 



A. polystyla Stein (Fig. 318, i). About 50/i long; salt water; Woods 

 Hole (Calkins). 



