The stucly of the arthropod head offers some of the most interesting and important evidence indicating the paths of development followed in the evolution of the various types of arthropods, but the evidence from this source has not been brought together, and nrost of the important types of head capsule have not been figured. The present paper, and the one following it, are offered with a view to supplying this needed information; and in these papers especial attention has been paid to the Crustacea, since these furnish the proto-types of many of the modifications met with in the Insecta, Chilopoda, Diplopoda, etc., and the carcinologists have neglected to furnish us with figures of these important forms.

Length 2.5-3.2 mm.; width 1.7-2 mm. Oblong-oval, moderately robust and convex; red or reddish-yellorv. Head three-fourths as long as wide; finely, sparsely, and uniformly punctate: vertex with two or three coarse punctures. Antennae concolorous; the second and third segments subequal in length; the club and stem subequal in length.

The author of this paper is indebted to Dr. C. P. Gillette of the Colorado State Agricultural College for the privilege of studying a part of the State College's collection of Siphonaptera, in which were found the two new species described below. Unfortunately the specimens of these two new species are somewhat mutilated but after careful examination it is possible to publish the following descriptions.

Holotype: Shape and Size: Broadly oval, elytra somewhat inflated so that the maximum width is in front of middle. Length: 9.59 mm.: width: 6.3 mm.

Color: Black above, piceous brown below, the posterior tibiae and femora darker; antennae brown, the basal joint of club dark. Shining.