North American Fresh-water Ostracoda. 425 



is two fifths loDo-er than the third segment; third and 

 fourth segments of equal length. Terminal claw of 

 third pair as long as the united lengths of the last 

 three and a half segments (Fig. 6); antepenultimate seg- 

 ment as long as the last two segments, the spine-like 

 seta on its inner distal edge of the same length; width 

 of basal segment one fourth its total length; two spine- 

 like setae on its lower inner edge, the distal seta twice 

 the length of the other. 



Rudimentary caudal rami (Fig. 3) cylindrical, thick, 

 blunt, about three times as long as wide, with a small 

 seta near base, not over two thirds as long as the width 

 of the ramus, and a stouter one near the tip of the 

 ramus, twice as long as the preceding one. 



The posterior dorsal part of the carapace (Fig. 7) 

 tapers to a spine-like point, and upon the dorsal aspect 

 there are several rows of tooth-like notches. 



Described from several specimens taken from a small 

 pond (Hedges' Pond) south of Urbana, 111., April 10, 

 189(). A number were raised from mud taken from the 

 bed of the pond. 



Limnicythere illinoisensis n. sp. (Pl.XXXIX Fio- 8~ 

 13; and PI. XL.) '' '^' 



A medium-sized species, .88 mm. long, .40 mm. high, 

 and .29 mm. wide; dark grayish white. A few scatt^er- 

 iDg hairs on the surface of the shell, which is rather 

 inconspicuously marked on its entire surface with polyg- 

 onal areas, which are, however, very faint compare'd 

 with those of Z. reticulata. With a high power these 

 areas are found to be filled with small elongate-oval 

 to quadrangular granules (PI. XXXIX., Fig. 9). 



Seen from the side (PI. XXXIX., Fig. 8), the shell is 

 evenly and gradually rounded at both ends, the dorsal 

 margin straight, the ventral deeply sinuate, the deepest 

 part at the anterior third, just below the muscle im- 

 pressions. (In L. reticulata the deepest part is just pos- 



