MARINE PROTOZOA FROM WOODS HOLE. 
447 
Although Quennerstedt’s description of L. pusillus makes no mention of a caudal bristle, the size 
and other characters are so closely similar that I hesitate to make a new species. The bristle is 
extremely delicate, scarcely thicker than a cilium, and easily overlooked, yet with proper focussing 
of the condenser I found it on every specimen examined. 
Key to marine genera of Opalinidee. 
Diagnostic characters: The form is oval, and the body maybe short or drawn out to resemble a worm. They are char- 
acterized mainly by the absence of mouth and pharynx. 
Anterior end not pointed; body cylindrical; tapering 
Anterior end pointed; body elongate; cylindrical; tapering 
Genus ANOPLOPHRYA Stein ’60. 
(Stein ’60; ClaparOde ’60; Leidy ’77; Vejdovsky ’79; Kent ’81; Balbiani ’85 ; Biitschli ’88; Shevyakov ’96.) 
The general form is elongate, cylindrical or slightly flattened, with rounded ends, the posterior 
end tapering. The body is striated with clearly defined, often depressed lines, which run longitudi- 
nally and sometimes spirally. The contractile vacuoles are usually placed in rows upon the edges. The 
macronucleus is almost always long and band-formed, rarely oval, and generally extending through 
the entire length of the body. Micronuclei have been made out in one case. Reproduction is effected 
by simple cross division or by budding at the posterior end, and is frequently combined with chain 
formation. The main characteristic is the entire absence of mouth and oesophagus, the animals being 
parasitic in the digestive tract of various annelids. Parasites, salt-water forms. 
Anoplophrya branchiarum Stein ’52. Fig. 44. 
A. circulans Balbiani. 
The body is cylindrical to pyriform, in the latter case broadened anteriorly. Cuticle distinctly 
marked by longitudinal striations which take the form of depressions and give to the body a charac- 
teristic melon shape. The endoplasm contains a number of large refringent granules — probably 
body products. The nucleus is elongate, somewhat curved, and coarsely granular. A micronucleus 
lies m the concavity. The cilia are long, inserted rather widely apart along the longitudinal mark- 
ings. The contractile vacuole is single and is located at the pointed end, which is directed backwards 
during locomotion. One specimen found free swimming among some algse. 
Length 104/u; greatest diameter 3 6/c 
Genus * Anoplophrya, j>. 447 
Genus Opalinopsis 
