tergites the antelateral lobes are very small [pl. 66, fig. 6] or altogether absent in the last.
The opercular plate has not been observed. The sternites [pl. 66, figs. 7, 10] are longer than the tergites, their anterior and posterior margins similarly subparallel and curve gently forward. The antelateral angles are furnished with blunt triangular lobes while the postlateral angles are well rounded.
Postabdomen. The postabdominal segments [pl. 66, figs. 5, 9] are annular, gradually increase in length and decrease in width posteriorly, so that while the first is three times as wide as long, the last is about as long as it is wide at its proximal articulation. The postabdomen is about one third of the body in length and decreases by one half its width from the first to the sixth segment. The first [fig. 5] postabdominal segment is produced into long bladelike lobes which attain nearly half the length of the segment; the others [pl. 66, fig. 9] possess only small acute postlateral lobes. The posterior doublure is distinct and occupies about one fourth the length of the segment.
The telson is identical with that of H. socialis; it is lanceolate, relatively short (not one fifth the length of the body) and apparently convex on the upper and flat on the under side. It is slightly contracted at the proximal end and widest at about one third of its length. The dorsal surface carries a median carina which begins a little behind the anterior edge of the telson and continues to the point. The lateral edges are sharp and furnished with a thickened, flat border.
Appendages. Our knowledge of the appendages of this species is still very incomplete as but very few entire specimens have been obtained and they show only traces of these organs. The crawling legs appear to have been both short and slender as in H. socialis. The swimming legs have been seen in two specimens [pl. 65, figs. 6, 8]. They are small (extending when reflexed to the fourth tergite) and slender. The fourth, fifth and sixth articulations are nearly equal in length, and gradually widen. Their distal edges are lobed or fringed. The seventh and eighth
