82 Wisconsin Academy of Sciences^ Arts, and LeUers. 



SPECIES 3. 

 Plate II. Figs. 8, 9. 



Ceeiodaphnia Cristata. sp, nov. 



Length, circ. 0.7 mm. 



Head not angulated in front of antennules. Post-abdomen 

 with a dorsal row of teeth. Valves with irregular meshes around 

 the edges and perpendicular striee across the middle, as in Simo- 

 cephalus. 



In general shape this species resembles C. dentata. The head 

 is rounded regularly over in front, not angulated in front of the 

 antennules. The valves are marked much as in Simocephalus. 



The post-abdomen is broad, somewhat truncate below, with 

 large, smooth terminal claws, and four teeth on each side of the 

 arms. The dorsal margin of the post-abdomen is produced into a 

 crest which bears eight or nine teeth, largest at the distal end of 

 the row. The apices of these teeth are directed upward. This 

 feature curiously recalls the teeth of the post-abdomen in Eury- 

 cercus. 



The eye is very large ; the macula nigra is of moderate size, 

 and is angular. 



The name is given on account of the crest on the post-abdomen. 

 Southampton, Mass., 1878. Eare. 



GENUS 3. 

 Simocephalus. Schodler, 1858. ' 



Simocephalus, Schodler, Branch, der Umg. von Berlin, p. 17. 

 " Sars, P. E. Miiller, Kurz. 



SPECIES 1. 



Plate I. Fig. 6. 



Simocephalus Americanus. sp. nov. 



Length, 1.5-2.5 or 3.5 mm. 

 Head angulated in front, with three or more teeth at the angle. 



