The coxae of the swimming legs are apparently large, occupying in length one half that of the carapace and of the usual trapezoidal outline. The following segments of the swimming legs are short and stout but not as short as in the typical forms. Likewise the next two segments (nos. 4 and 5) are long and tubular like those of the walking legs. The sixth segment is shorter, and the seventh and eighth are broadened to about double the width of the other segments to form the paddle. They were of subequal size; the eighth segment formed a broad oval approaching a circle.
The metastoma appears to have been broadly elliptic (length to width as 3 : 2), not half as long as the carapace.
The genital appendages have been seen only as faint shadows, too indistinct to describe.
The ornamentation of the surface is also obscured to such an extent by secondary roughening and wrinkling of the integument that nothing reliable can be ascertained.
Measurements. The largest specimen (no. 12905, University of Chicago collection) measures 160.5 mm in length and 53.5 mm in greatest width. Its carapace measures 35 × 49 mm. The rim is 4 mm wide, the eyes are 10 mm long, the metastoma 14.5 mm. The swimming leg projects 41 mm beyond the margin of the carapace. The preabdomen is 40 mm long and 53.5 mm wide; the postabdomen is 50 mm long, 43 mm wide at its proximal end and 14 mm at its distal extremity. The telson measures 35+ mm. In another well preserved specimen (no. 12907, University of Chicago collection), which is 154+ mm long, the dimensions of the carapace are 33 × 48 mm; those of the preabdomen 43.5 × 52.5 mm, of the postabdomen 41.5 mm, of the telson 36+ mm.
Horizon and locality. Kokomo waterlime, Kokomo, Indiana.
Remarks. This is probably the species cited by Claypole [1890, p. 259] as E. lacustris from Kokomo, for in its broad carapace it is most likely to suggest that form. It resembles still more, however, the E. dekayi of the Buffalo waterlime, which is built on like proportions,
