1889.] ON SOME FRESHWATER OSTRACODA AND COPEPODA. 9 



wedge-shaped. There is moreover no trace of the crenulate arma- 

 ture to be found on the right valve, which is exactely like the left. 



The colour of the shell is yellowish, when the animal is in a 

 living state, with two irregular, somewhat oblique, dark brownish 

 patches on either side, limiting an irregular oblong area of a 

 lighter colour, which extends obliquely upwards from the central 

 region of the shell. The anterior patch is continued down the 

 sides to the region within which the oral parts of the animal 

 are situated, whereas the posterior terminates about in the 

 middle of the valve, and from this point a narrow diagonal 

 stripe runs posteriorly immediately above the coecal appendage 

 of the intestine. Moreover, a narrow bandlike patch of the 

 same dark colour is seen extending along the anterior extremity 

 at a short distance from the edge. Through the shell also some 

 of the inner parts of the animal are more or less distinctly 

 seen. Thus in the anterior part, above, the eye is readily ob- 

 served, and in the posterior part the coecal appendages of the 

 intestine appear very distinctly as a narrow diagonal band 

 extending from the central part of either valve to its posterior 

 extremity and generally exhibiting a very conspicuous bright 

 greenish colour. Just above this band a faint orange shade is 

 more frequently observed in adult females, indicating the place, 

 where the ova lie accumulated within the body. In the males, 

 moreover, the testicular coeca, or spermatic tubes, lying between 

 the lamellae of the valves, are at once distinguished, forming in 

 the posterior part of the shell, on either side, 4 concentric arcs 

 (see PI. l, fig. 3). 



In order to examine the animal with its several appendages 

 in their natural situs, it is proper to kill the specimens in 

 hot water, when the valves open widely so as easily to be 

 separated. On removing only one of the valves and leaving 

 the animal within the other, it is found (see PL IV, fig. 1) that 

 the body does not by far fill up the cavity of the shell, a con- 

 siderable space being left anteriorly for the reception of the 

 antenna?, when not in action, and also inferiorly and posteriorly 

 there is some room between the inner face of the valves and 



