890 MR. J. Y. JOHNSON ON NEW CRUSTACEANS. [NoV. 28, 



than the third, which is cylindrical. Filaments ? The cylin- 

 drical peduncle of the inferior antennae does not extend quite so far 

 as the basal joint of the superior antennae. It carries a single fila- 

 ment. The lamellar palp is narrowly oval, and reaches beyond the 

 peduncle of the superior antennse. Its upper surface is marked by 

 a deep longitudinal groove. The basal joint is unarmed. 



The external jaw-feet are pediform and slender. They extend 

 beyond the peduncle of the inferior antennse, but not so far as the 

 distal extremity of the superior antennae. The)' are furnished with 

 a many-jointed palp as long as the feet, fringed with hair on both 

 edges. The second joint has a sharp exposed edge ; and the lamellar 

 appendage attached to the basal joint is bifid and similar to the ap- 

 pendages of the ambulatory legs. The next pair of jaw-feet are 

 flattened, and are much shorter than either the external pair or their 

 own palps, which are not quite so long as the palps of the external 

 pair. The three remaining pairs of jaw-feet are elongate, imperfectly 

 divided into joints and very thin. The mouth is destitute of the 

 powerful cutting- and crushing-jaws which characterize the species of 

 the genus Penceus ; but it is furnished with a pair of long sickle-like 

 shears, which cross each other from opposite sides. At each side of 

 the mouth there is a broad lamellar appendage. 



None of the ambulatory legs is multiarticulate. They are slender, 

 and the order of their length is 4, 3, 5, 2, 1, the fourth pair being 

 the longest. The legs of the three anterior pairs are didactyle ; and 

 at the base of each of these legs there is a lamellar bifid fringed ap- 

 pendage. The legs of the two anterior pairs carry a spine at the 

 distal extremity and at the underside of the second and third joints. 

 The other legs are unarmed, but have hairs on the undersides or 

 edges of their joints. The legs of the third pair extend the furthest 

 forward, but they do not reach so far as the distal extremity of the 

 peduncle of the inferior antennae. The orifices of the oviducts are 

 on tubercles upon the inner side of the basal joint of these legs. The 

 sternum is very narrow, and has a protuberance between each of the 

 fourth and fifth pairs of legs. 



The unarmed abdomen is compressed and clothed with short hairs 

 on the less exposed parts. The sides are corrugated and project 

 over the bases of the false feet. The first segment is the highest, 

 the sixth the longest. A low median crest commences on the third, 

 and is continued on the fourth, fifth, and sixth segments. At the 

 sides of the anterior five segments there are ridges of irregular form. 

 On the sixth there are four straight longitudinal ridges in addition 

 to the median crest. At each side of the posterior margin of the 

 sixth segment there is a small projecting lobe, and a small tooth is 

 seen at each posterior angle. To the anterior five segments are 

 attached well-developed false feet with stout peduncles, bearing 

 (except in the case of the first pair) two many-jointed fringed palps, 

 the outer one being the longer. The false feet of the first pair have 

 only one palp that does not extend bej'ond the middle of the cara- 

 pace. The second, third, and fourth pairs of false feet are longer 

 than the first. The seventh abdominal segment, or middle caudal 



