234 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



long spines and aggregations of bristles and small spines; it is almost 

 round and enormously enlarged. The intestine is coiled and expanded 

 at the end but the anal ceecum is rudimentary. The antennae are 

 heavily spined and have eight setse; the labrum is more or less hairy. 

 The male has a strong hook on the first foot, and between the terminal 

 claws of the abdomen is a peculiar intromitteut organ, 



*L(eydigia quadrangiilaris Leydig. 



Plates LIX, Fig. 6; LX, Fig. 4. 



Lynceus quadranguJaris — Leydig, Fric. 

 Alona leydigii — Schoedler, P. E. Mueller. 



The shell is comparable to that of Alona quadrangularis, but higher 

 behind; the markings are not very distinct; shell transparent. The 

 head is very small; the eye smaller than or of about the size of the 

 pigment fleck. The post- abdomen is very broad, the i30sterior margin 

 nearly the segment of a circle, armed with numerous very long unequal 

 spines which extend only about half the height, being replaced by 

 short close hairs; the anal opening is very high; the terminal claws 

 are long, straightish, and have a small thorn near the base. 



The males are smaller than the females, and the abdomen is lesa 

 broad; the antennules are longer than the beak and furnished with a 

 flagellum. The sexual period occurs in September or irregularly. 

 This species has only been encountered once, during September, in 

 Poplar river, Cullman county, Alabama. 



*Iieydigia acanthocercoides Fischer. 



Lynceus acanihocercoides — Fischer, Leydig. 

 Eurycercus acanihocercoides — Schoedler. 

 Alona acanihocercoides — P. E. Mueller. 

 Leydigia quadrangularis — Herrick. 



This species, reported in a previous paper, is, as was said, nearest 

 like L. acanthocereoides; and I am now able to verify the very incon- 

 spicuous differences upon which the two are separated. Our specimens 

 of the L. quadrangularis have the pigment fleck fully as large as the 

 eye, Kurz to the contrary notwithstanding, and the spine of the claw 

 of the post-abdomen is present, while in the i)resent species the pig- 

 ment fleck is much larger and furnished with lenses; the spine of the 

 claw is wanting; the labrum is densely hairy; the abdomen is narrower^ 

 and the shell higher. The shell is very obviously striped in the pos- 



erior portion. The anus is higher than in the previous species. In 



ther respects the two seem alike. 



