ENTOMOSTRACA. OF MINNESOTA. 175 



abundantly everywhere. In this country at least it is characterized 

 by a dark color. The head is large, rounded in front of the large eye, 

 serrate below and extending posteriorly into a roundish beak, back of 

 which are the short antennules. The fornices are very short and 

 rounded; a line connects the fornices with the beak by a sudden de- 

 flection downward; it sets off the area which forms a part of the basin 

 of the antennce. A second line springing from just above the termin- 

 ation of the fornices passes over the eye by a broad curve. The post- 

 abdomen is truncate and bears beside the terminal claws four or more 

 spines which rapidly decrease in size. The claws are minutely spined; 

 the spines on the shell are of variable length, but do not exceed one- 

 fourth the length of the remainder of the lower margin. This species 

 ranges over all Europe and eastern United States. 

 Length 0.6 to 0.8 mm. . 



Scapholeberis eoriiuta Schoedler. 



Plate XLV, Fig. 6. 



Mbnoculus bispinosus — De Geer. 



Daphnia mucronata var. acute rostrata — Baird. 



Scapholeberis mucronata var. fronte cornuta — P. E. Mueller. 



This species differs from the above only in having a sharp curved 

 horn on the head in front of the eye. The use of this appendage can 

 only be conjectured; but it may be that, like the curved beak of Bip- 

 opliilus, it serves to clear away rubbish in the filth in which these ani- 

 mals frequently live. This form, be it variety or species, is not known 

 in America. 



* Scapholeberis armata Herrick. 

 Plate XLII, Figs. 10, 11. 

 Scapholeberis mucronata var. armata — Herrick. 



A very beautiful and unique species, which possesses the extreme 

 development of the peculiarities of the genus. The head is shaped 

 very much as in the previous species, the fornix is squarish, the basin 

 for the antennsB is small. The upper lines from the fornix meet be- 

 hind the eye; the form of the shell is as in the above, but the spines 

 upon the lower margin are longer. The scythe-like spine on the lower 

 angles of the valves is extremely long, falling little short, in extreme 

 cases, of being as long ias the entire lower margin, in others about one- 

 half as large. There are the usual lines parallel to the lower edge 

 of the shell. The specimens having the longest spines were found in 

 fresh water about Mobile, Ala. , but the species occurs in Minnesota 

 and intermediate points, though sparingly. Probably the earlier plan 

 of regarding this as a variety of S. mucronata is nearer correct. 



