OCR Text |
Show 896 MR. J. Y. JOHNSON ON NEW CRUSTACEANS. [Nov. 28, than the third, which is cylindrical. Filaments ? The cylindrical peduncle of the inferior antennae does not extend quite so far as the basal joint of the superior antennae. It carries a single filament. The lamellar palp is narrowly oval, and reaches beyond the peduncle of the superior antennae. 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 antennae, but not so far as the distal extremity of the superior antennae. They 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 appendages 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 tbe 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 Peneeus ; 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 appendage. The legs of the two anterior pairs carry a spine at the distal extremity and at tbe 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. Tbe 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 tbe 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 beyond the middle of the carapace. The second, third, and fourth pairs of false feet are longer than the first. The seventh abdominal segment, or middle caudal |