On Fresh-water Eiitomostraca. 51 



evenly rounded, posterior subtruncate and scarcely broader 

 than the anterior, dorsal margin almost angularly bent in 

 the middle, ventral but very slightly sinuate; seen dorsally 

 oblong cuneiform, gradually tapering in front, anterior extre- 

 mity acuminate, posterior obtuse. Valves nearly equal, 

 left one having the edge minutely tuberculated in front and 

 behind; inner duplicatures not very broad. Surface of shell 

 remarkably smooth and polished, being clothed at both extre- 

 mities with minute hairs. Caudal rami rather slender and 

 slightly flexuose, narrowed distally, outer claw about half 

 the length of the ramus. Length of shell 2,70 mm. 



Remarks. — The present species is allied to C. sydneia, 

 but is evidently distinct from it, being nearly twice as large and 

 having the shell higher in proportion to its length. It is 

 named in honour of its discoverer, Mr. Lea. 



Description of the female. 



The length of the shell measures 2,70 mm., and this 

 form accordingly grows to a very large size. 



Seen laterally (fig. 2 a) the shell exhibits a somewhat 

 irregular, oval reniform shape, with the greatest height, 

 which about equals 3 /s of the length, occurring in the middle. 

 The anterior extremity is quite evenly rounded, whereas the 

 posterior one appears somewhat obtusely truncated, and is 

 scarcely broader. The dorsal margin is boldly arched, being 

 almost angularly bent in the middle, and slopes at about 

 the same angle both anteriorly and posteriorly. The ventral 

 margin appears nearly straight, though a slight sinus may 

 be traced in the middle. 



Seen from above (fig. 2 b), the shell exhibits an oblong 

 cuneiform shape, with the greatest width, which about equals 

 half the length, occurring far behind the middle. Anteriorly 



