50 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



cilia are densely arranged. Pharynx wanting ; striation 

 and ciliation regular. On the posterior end a bristle. 

 U. marinum (?) Duj., Fig. i8i, two varieties. 

 Dexiotricha Stokes. 



Similar to the above, but with a spiral row of cilia. 

 D. plagia Stokes, Fig. 197. 

 Cinetochilum Perty. 



Rigid, flattened, oval, with deeply spiral furrows. 

 Upon the ventral side, beginning at the posterior end, is 

 a peristome slightly widening in front, where the mouth 

 is found, surrounded by an undulating membrane. Cilia- 

 tion uniform. At the posterior end, upon the right and 

 left, a few long, thread-like cilia. Contractile vacuole 

 posterior, upon the right. 

 C. margareticiim Ehrbg., Fig. 199, ventral and lateral 

 views. 

 Microthorax Engelm. 



Small, nearly oval, the left side straight and the right 

 curved. Ventral surface flat, with two furrows parallel 

 to the right side ; dorsal edge curved. Mouth in a flat 

 peristome, posterior, upon the left side, with an undulating 

 membrane on the right. Cilia few, uniform. Nucleus 

 central ; contractile vacuole in front of the mouth. 

 M. sulcatus ( ?) Ehrbg., Fig. 200, is our common form, 

 but it appears to be smaller than the species sulcatus. 

 Lembadion Perty. 



Rigid ; oval when seen from the back. Posterior end 

 somewhat acute, anterior end oblique. Ventral surface 

 flat, dorsal convex. A large peristome, which almost 

 covers the whole of the right side of the body, and which 

 carries on its left side an undulating membrane, almost 

 filling the peristome. Striation longitudinal ; ciliation uni- 

 form, but with a tuft of posterior, longer cilia. Nucleus 

 short, cord-like. One contractile vacuole. 

 L. huUinuni Perty, Fig. 204. 

 Pleuronema. Duj. 



Somewhat oval and flattened dorso-ventrally ; both 

 enils rounded ; left side more curved than right side. 

 Upon the right side of ventral surface is a large, furrow- 



