ENTOMOSTRACA OF MINNESOTA. 169 



liar track. The length is sometimes 1.0 mm. The head is obscurely 

 angulated in front of the antennules, which are large. The antennules 

 of the male are long and have hooked seta at the end. 



The description of GeriodapJinia cnstata given by Birge would apply 

 in almost every particular to G. megops, though he seemed to overlook 

 the close conformity. The size is much less (0.7 mm.), and the post- 

 abdomen seems more abruptly truncate; moreover the number of anal 

 spines is less. The crest upon the dorsal margin may be the effect of 

 prominences such as are described by P. E. Mueller; at any rate, in 

 view of the fact that but few specimens were discovered, the sugges- 

 tion lies near thvit G. crisiata is the young or, at least, a reduced form 

 of G. megops. Professor Birge writes that he now unites crlstata with 

 {7. megops. 



Found at Southampton, Mass. 



Cerioflaplinia pulcliella Sars. 



Plate XLI, Figs. 14, 19. 



Very much like G. reticulata, but smaller. Head large, turgid, and 

 angled in front of the antennules, foi-ming almost a right angle; for- 

 uices moderate; antennules rather large; shell oval, reticulated with 

 double contour lines; post-abdomen of medium size, narrowed toward 

 the end, slightly truncate, with about nine spines; terminal claws 

 short, smooth. The flagellum of the male antennre is but slightly 

 hooked, 0.5 to 0.(3 mm. long. This species is not certainly identified 

 from America, though a form with smooth claws and small fornices 

 occurs with G. dentati in some places. 



Ceriodaphnia rotunda Straus. 



Plates XLT, Figs. 12, 23; XLII, Fig. 1. 



Daphnia rotunda — Straus, Baird. 



As said by Kurz, this species is not easily mistaken; the small head 

 (only paralleled by the following), the very evident reticulations and 

 the broad abdomen give it a peculiar habitus which is unmistakable. 



Head depressed, small, spiny below, not angulated; fornices promi- 

 nent, thorned; body rotund, almost spined above; shell doubly retic- 

 ulate; post-abdomen broad, with seven or eight anal spines; claws 

 large, smooth. The male antennules are little larger than those of the 

 female. I have not yet seen this species in America. 



