MARINE PROTOZOA FROM WOODS HOLE. 
455 
below. The anus is posterior and on the right side. The characteristic macronucleus is long and 
band-form, its main portion being usually on the left side with an anterior and a posterior arm 
toward the right. Movement is rapid swimming, which, however, is frequently broken by creeping 
periods, during which the animals appear to he examining the foreign body on which they creep. 
Fresh and salt water. 
Euplotes charon Ehr. Fig. 52. 
Synonyms: Triclioda charon Muller; Plcesconia charon; P. affinis , subrotunda , racliosa , longiremis, Dujardin ’41. 
The body is oval, small, and somewhat variable in length. The carapace is strongly marked upon 
the dorsal side by deep longitudinal grooves, 6 to 8 in number; the grooves may be absent, however. 
The adoral zone extends to the posterior third of the body, the mouth and oesophagus are directed 
anteriorly. There are 10 ventral cirri, 7 of which are on or near the frontal border and 3 near the 
right edge. There are 5 posterior cirri and 4 anal cirri, of much smaller size. The cirri may or may 
not be fimbriated, the latter condition indicating the approaching disintegration of the body and is 
abnormal. The macronucleus is long and band-formed or horseshoe shape. The contractile vacuole 
lies on the right side dorsal td the posterior cirri. 
Fresh and salt water. Length 45;/; diameter 25//. 
Euplotes harpa Stein. Fig. 53. 
The body is elongate, oval, somewhat widened anteriorly, and has rounded ends. The frontal 
margin is three-toothed. Ten ventral cirri. Dorsal surface provided with 8 longitudinal markings. 
The peristome is long and broad, with considerable variation. The adoral zone consists of powerful 
membranelles arranged in a continuous curve from the mouth to the extreme right frontal margin. 
Seven of the 10 ventral cirri are situated at the anterior extremity; the remainder are arranged in a 
triangle on the right edge. The anal cirri, 5 in number, are long and stiff; the marginal cirri smaller 
and finer. The nucleus and contractile vacuole are similar to those of the preceding species. 
Length 95//; width 54//. 
Fig. 52. — Euplotes charon, dorsal and ventral aspects. 
