Marshall—Ten Species of Arrenuri. 
153 
another tiny pointed process which m]ay represent the petiole 
( r). 
The length is 1*2 man:; the width, 0.6 mmj; and the height, 
0.55 mm. The color is a light bine-green with dark flecks and 
a touch of red on the dorsal shield. 
Arrenurus cardiacus, nov. spec. 
Fig. 5, or-e. Pis. XVII, XVIII. 
This form is most closely related to A. securiformis Piersig 
and A. cylindratus Piersig, from both of which it differs in the 
structure of the posterior part, of the appendage. 
In form the body is much like A. securiformis. The dorsal 
shield is oblong and the genital area forms prominent rolls 
between body and appendage. The fourth pair of epimera 
are scarcely wider than the third and the posterior border is 
concave, corresponding with the position of two little stigmata 
bearing hairs lying just back. When viewed laterally the body 
is seen to be strongly arched on the dorsal side. 
The appendage is much lower than the body from which it 
is sharply marked off. There is a constriction at the base and 
another in the last third. It is widest near the end and the 
side corners are prominent. From this point there is a strong 
bowing-out posteriorly with a deep' and wide bay in the cen¬ 
ter. A slight rounded mound lies in the bottom of this bay, 
and other small ones lie in this region as shown in the figures 
(fig. 5, a and c, IT, 2 H, 3 H 4 ). Anterior to this deep and wide 
bay is the second distinguishing feature of this species and the 
one which has suggested its name: it is a broad heart-shaped 
hump, the point directed forward (H 1 ). This hump is simi¬ 
lar to that in A. cylindratus in the same place, but is wider. 
It is the point of this hump which forms the prominent eleva¬ 
tion on the appendage in the lateral view. The position of the 
numerous hairs is seen in the figures. 
The palpi show the usual structure. The inner edge of the 
fourth joint is drawn out into a broad process on which grows 
a broad bladeTike hair. The small curved claw-like fifth seg¬ 
ment is bifurcated. The mandibles are shown in fig. 5, e. 
