ENTOMOSTEACA OF MINNESOTA. 325 



■distance, this band forms a convex curve and passes caudo-dorsad 

 almost to the margin of the shell. From the caudo dorsal angle of the 

 square a short band passes dorso caudad and fuses with a broader band 

 which passes caudad, approximately parallel to the dorsal margin of 

 the shell. From this same corner another band passes caudo-ventrad 

 almost to the caudal margin of the shell. This band is approximately 

 parallel to the band just described. From the caudo-ventral angle of 

 the square a band passes caudo-ventrad almost to the caudo ventral 

 extremity of the shell. In the caudal portion of its course this band 

 curves dorsad, otherwise it is approximately parallel to the band last 

 described. From the cephalo- ventral angle of the square, a short band 

 projects ventrad and then broadening, forms a boot-shape band. The 

 short heel of this boot projects caudad and terminates in a point, the 

 long toe extends cephalad and terminates bluntly. From the same 

 corner of the square, a second band projects cephalad to about the 

 level of the toe of the boot. There it fuses with a spike shaped band 

 which extends cephalo-ventrad from near the cephalo-dorsal angle of 

 the square to about the cephalo ventral extremity of the shell. The 

 head of the spike is at the caudo-dorsal extremity of the band. The 

 two bands fuse near the head. 



The number of lucid spots is about eight. They are situated in the 

 centre of the valve and ordinarily are inclosed within the square above 

 described. 



Viewed from the ventral surface one valve overlaps the other in 

 front. The contact line is sinuous, being laterally convex at the mid- 

 dle. 



Viewed from the end the shell is oval in shape, the greatest width 

 being near the dorsal surface. 



Antennie slender; the natatory setie on the distal extremity of the 

 third joint reach almost or quite to the tip of the long and slender 

 terminal claws. 



The mandible is stout. Among other sette, the antepenultimate 

 joint of mandibular palp bears a short, pectinated, dagger-shape seta; 

 so does the penultimate joint. 



Tlie two biarticulate claws on the first mandibular process of the 

 first maxilla are smooth. The extremity of that same process bears 

 two setfe as long as the biarticulate claws; one, which is curved and 

 smooth, is situated at the outer angle and the other, which is straight 

 and pectinated, is situated about the middle of the extremity. 



Tbe terminal claw of the first leg is almost as long as the entire 

 limb. The distal two-thirds is pectinated. 



Tlie post-abdomen is long, slender and straight. The distal portion 

 of its outer margin is pectinated. The terminal claws are curved and 

 are a little longer than half the length of the abdominal rami. 



