* 
( 16 ) 
inner inferior angle of the second joint. The body of this species is broader 
than in D. castor , the color is throughout a deep red. The antennae are 
nearly as long as the body, the eighteenth joint in the female reaching to the 
base of the abdomen. The second tooth of the mandible is larger than any of 
the remaining six of the series, and is separated from the third by an interval 
equal to the width of the tooth. A short feathered bristle appears at the 
lower end of the row of teeth. The secondary appendage of the mandibular 
palpus is four-jointed, and bears six bristles at its tip and inner margin. 
The maxilla has the normal structure, the basal plate, the two cylindrical 
processes and the outer ramus (flabellum) and the inner ramus being all 
present and symmetrically developed. The first maxilliped is nearly as 
broad as long, and bears 15 long hairs on its margin. The basal segment of 
the second maxilliped presents four rounded processes on its inner margin, 
of which the first is smallest and bears one bristle, the second and third are sub- 
equal and bear respectively two and three bristles, and the fourth is largest, 
is much produced inferior ly (the rounded lower end being finely cilia te) and 
bears four bristles. 
The fifth pair of legs in the female is bi-ramose, the inner branch 
straight, slender, not jointed, terminating in two short claws; the outer 
strong, two-jointed, terminating in a single slightly serrate claw. The sec- 
ond joint of this branch bears two slender bristles near the middle of the 
outer margin, otherwise the leg is destitute of hairs and spines. The legs of 
the fifth pair in the male are very dissimilar. The right leg consists of five 
joints ; the basal quadrate ; the second about twice as wide as long, en- 
larging distally and bearing a strong blunt spine at the inner, and a longer 
one at the outer, inferior angle. The third joint is sub-quadrate, the fourth 
clavate, bearing a long bristle at the middle of its outer margin ; and the 
fifth constitutes a slender incurved dactyl as long as the preceding joint, 
slightly serrate on the distal half of its inner margin, and so jointed as to 
close back against the inner margin of the fourth joint, which thus acts as 
a hand. The left leg reaches about to the tip of the third joint of the right. 
Its pedicel contains two large quadrate joints ; the outer ramus two small 
joints, of which the terminal one is forcipate at the tip, the inner ramus a 
single slender joint on which no armature was seen. The furca bears at 
tip of each branch four long feathered hairs, and a fifth smaller simple one 
at the posterior internal angle. A sixth large and plumose hair is borne at 
the posterior third of the outer margin. 
Found rather abundantly in a pool fed by a slow spring, ia March and 
April, at Normal, Illinois. In several characters, especially those of the 
mouth appendages, this species seems closely allied to Ichthyophorba, bear- 
ing to some species of that genus a much closer resemblance than to D. 
castor , if the figures in Baird’s British Entomostraca are at all to be relied on. 
