248 NEW YORK STATE MUSEUM 
existence, they could be of no more than varietal importance. We here 
refer all specimens of Eusarcus from Kokomo to one species which has 
the following characters. 
Description. General form that of a rather short, posteriorly broad 
oval body (carapace and preabdomen) with abruptly attached tubular 
tail (postabdomen) of equal length with the body, and a rather short, 
stout tail spine. | | : 
Cephalothorax broader than long (proportion of length to width as 7 : 8 
in the youngest specimen), the difference decreasing with increasing age, 
in the largest example being reduced to but one fourth of its earlier size; 
outline a regular triangle with truncated angles, the lateral margins moder- 
ately convex,' the posterior margin gently concave in the middle, almost 
straight. Posterior truncating line or postlateral angles very gently 
convex; frontal margin probably slightly emarginate between the eyes. 
The lateral eyes have been seen only in the largest specimen; they are 
located at the antelateral angles, are of bean-shaped outline and about 
one fifth the length of the lateral margin. Their structure has not been 
observed; nor have the ocelli been seen in any of the specimens. 
Abdomen. Preabdomen relatively shorter than in any of the other 
species ; a little longer than the carapace and nearly twice as wide; broadens 
in continuation of the lateral margins of the carapace to the fourth tergite, 
whence it contracts rapidly to the powerful postabdomen which is twice 
as long as the preabdomen and two fifths as broad. | 
The outlines of the separate tergites and sternites have not been dis- 
tinguished with clearness and no separate plates observed; hence no detailed 
description of their form and relative dimensions can be given, but enough 
has been seen to prove that they do not differ materially from the cor- 
responding parts of the better known E. scorpionis, although it is 
1 In the smallest specimen they are gently sigmoid in outline, their anterior half 
being gently concave, a feature that is not observed in the other specimens and quite 
probably due to differences of preservation, as suggested by a like difference in equal 
sized specimens of E. scor-pionis. 
