344 NEW YORK STATE MUSEUM 
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 1s 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 post- 
lateral 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 asin 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 
