80 Wisconsin Academy of Sciences, Arts, and Letters. 



GENUS 2. 



Ceeiodaphnia. Dana. 



Ceriodaphnia, Dana. U. S. Expl. Ex. Crustacea, Vol. II, p. 1265. 

 Sars, P. E. Mliller, Kurz. 



SPECIES 1. 

 Plate I. Figs. 1-3. 



Ceeiodaphnia Dentata. sp. nov. 



Head angulated in front of antennules. Shell reticulated with 

 hexagonal meshes. Terminal claws with a row of teeth on out- 

 side and finely serrate inside. 



The head is prolonged, and is distinctly angulated in front of 

 the antennules. The shell of the head and body is reticulated 

 with hexagonal meshes. The lines of reticulation vary from al- 

 most imperceptible to very strongly marked, in different speci- 

 mens. The shell may be transparent or opaque. There is a dis- 

 tinct projection at the junction of the dorsal and posterior mar- 

 gins, almost a spine. The fornices are broad and projecting, but 

 are smoothly rounded over and have no angular projection. The 

 post-abdomen is of moderate size, truncate, with seven or eight 

 caudal teeth on each size, and with scattered, very fine hairs. The 

 terminal claws are armed with from to 8 (usually 6) teeth on 

 the outer side. The teeth vary much in size, are often exceed- 

 ingly fine, and rarely altogether absent. There is also a row of 

 very fine teeth extending to the tip of the claw. This is only to 

 be seen in good specimens and with a high power ( ^ Wales), and 

 sometimes, though rarely, cannot be seen at all. The abdominal 

 process is rather blunt, and has fine hairs scattered upon its sur- 

 face, as has also that part of the abdomen behind it. Cambridge. 

 Southampton and vicinity, Mass.; Madison, Wis. Male not seen. 

 C. reticulata (Jurine) has the terminal claws provided with teeth, 

 but in this species the fornices are " permagnge et valide promi- 

 nentes " (P. E. M.), and have a sort of triangular projection in front. 

 The fornices in this species are of medium size, and have no such 



