20 



mm. Body quadrate, or sac-like, or strongly arched dorsally. 



Notops. 

 hh. Corona without prominences bearing styles, consisting of an 

 oblique (or even ventral) disk or area covered with close set 

 cilia or with numerous interrupted ciliary curves ; two lateral 

 evertible ciliated projections (auricles) present in many 

 species ; jaws forcipate ; soft flexiljle elongate species. 



NOTOMMATID.^. 



i. Parasitic. External, Pleuratrocha ; internal, Albertia and 



Proales. 

 ii. Not parasitic, 

 j. Body elongate, fusiform with numerous marked annulations ; 

 head enlarged, with a decurved hood or fleshy proboscis in 

 front; free swimming. Taphrocampta. 



jj. With other characters, 

 k. With one or no eyes. 



I. No eyes ; indications of neck, a small hood like proboscis in 



front ; auricles present. Pleurotrocha. 



II. One eye. 



m. Eye in the neck some distance from the front of the head. 



n. Body with numerous prominent annulations or crenula- 



tions. Taphrocampa. 



nn. Without such annulations though divisible into a number 



of joints. 



o. Species .2 to .7 mm. in length, brain three to five lobed. 



Copeus. 

 00. Smaller species ; if large, their body is sac-like or with- 

 out auricles, 

 p. Auricles present ; brain usually partly opaque, not three 

 lobed. Notontmata. 



pp. Auricles absent ; brain clear. Proales. 



mm. Eye frontal, placed near or at the anterior end of the 

 body ; body cylindrical. Furcularia. 



kk. With two or three eyes. 



I. With three eyes. 



m. Eyes in a transverse row near posterior end of the brain. 



Triophthal)n us. 

 nim. One large eye in the neck, two smaller ones on the front. 



Eosphora. 



II. With two eyes. 



m. Eyes frontal (fig. 19). Diglena. 



mm. Eyes in the neck. Disteiiiiiia. 



dd. With a stiffened cuticle forming an armor. LORICATA. 



e. Foot present, 

 f . Foot transversely wrinkled or ringed ; very retractile, 

 g. Foot ending in a ciliated cup ; armor dorso-ventrally flattened, 

 thin ; corona transverse, ciliary w'reath two lateral semi-circles ; 

 eyes two (figs. 28, 29). PTERODINID.E, Pterodina. 



gg. Foot ending in one or two, usually small, toes. 



