MUSEUM OF COMPAKATIVE ZOOLOGY. 83 



distal end ; the second and third segments are subequal in length, and the ter- 

 minal is considerably prolonged beneath at the origin of the lower flagellum ; 

 the inner and distal margins of the first segment, and nearly the whole exposed 

 surface of the second and third, are thickly clothed with hair. The proximal 

 part of the lower flagellum is about as stout as the flagellum of the antenna, 

 nearly cylindrical, and naked ; while the upper is considerably stouter and 

 ciliated along the inner side. 



The segments of the peduncles of the antenna? are all smooth, nearly naked, 

 and externally unarmed, but the second segment bears, on the upper and inner 

 edge, a slender spine curved forward and outward above the base of the scale, 

 and there is a papilla-like prominence just above the opening of the green 

 gland at the distal extremity of the first segment ; the consolidated fourth and 

 fifth segment is about as long as the three others taken together, is sub- 

 cylindrical, and the distal segment prolonged in a thin triangular process inside 

 the origin of the flagellum ; the scale (Fig. l a ) is about two thirds as long as the 

 carapax, and about three times as long as broad, the greatest breadth being near 

 the base, but the margins only slightly converging distally except near the tip, 

 which is obliquely rounded and extends considerably beyond the acute spine in 

 which the very slightly arcuate outer margin terminates. The proximal part 

 of the flagellum is very slender, naked, and slightly compressed vertically. 



The labrum projects far below the epistome and is broadly caudate as seen 

 in front, but this form is perhaps a result of contraction due to preservation in 

 alcohol. The lobes of the metastome are narrow at the base, but expand into 

 very broad and obtuse tips. ( 



The mandibles (Fig. 2) are almost exactly alike, and nearly as in Penceus. 

 They are somewhat contracted at the crowns, which are small, with the oppos- 

 ing surfaces somewhat semicircular in outline and each divided longitudinally 

 by a narrow and shallow depression into two portions, of which the ventral is 

 obtusely triangular and obscurely bidentate, while the dorsal portion is long 

 and narrow anteriorly, but expanded at the posterior angle into a small and 

 somewhat oval molar area with a raised and obscurely dentate margin. The 

 mandibular palpus is composed of two lamellar segments, of which the proximal 

 is considerably the longer' and broader, while the distal is narrowly ovate with the 

 tip rounded ; both segments are margined with soft hairs and plumose setce. 



The proximal lobe of the protognath of the first maxilla (Fig. 3) is small and 

 ovate, the distal lobe obliquely truncated and armed as in the allied genera. 

 The endognath is narrow, curved, unsegmented, and shorter than the distal 

 lobe of the protognath. 



The four lobes of the protognath of the second maxilla (Fig. 4) increase suc- 

 cessively in size distally, the distal being twice as wide as the next. The 

 endognath is much shorter than the distal lobe of the protognath, and tapers 

 regularly to the tip. The anterior part of the scaphognath is much longer 

 than the posterior and projects beyond the protognath, while the posterior part 

 is short, broadly expanded, and strongly incurved at the extremity. 



The protopod of the first maxilliped (Fig 5) projects anteriorly in a straight 



