| OCR Text |
Show 898 MR. J. Y. JOHNSON ON NEW CRUSTACEANS. [Nov. 28, distance behind the posterior rostral tooth there is a tooth on the median crest of the carapace. The under edge of the rostrum is destitute of teeth. There is a fringe of hair in the neighbourhood of the rostral teeth, and on the under edge of the rostrum as far as the upper fringe extends. At the front border of the carapace there are four small teeth-one over the exterior base of each of the superior antennae, and one over the base of each of the inferior antennae. Each of these teeth forms the termination of a ridge; and of these ridges the two nearer the lateral margins of the carapace are higher and longer than the other two. About the middle of the height of the carapace there is another ridge on each side, but it does not extend backwards beyond the middle of the length of the carapace. Between the two principal ridges the carapace is concave ; and there is a furrow on the upperside of the exterior ridges; these furrows extend backwards to about the middle of the length of the carapace, and they then bend obliquely downwards towards the lateral borders. At the bend another furrow commences, which widens backwards and upwards until it reaches nearly to the posterior border of the carapace. An intramarginal furrow extends round the carapace, except in front; and the sides have a broad membranous border. The eyes are black, round, large, and of greater diameter than the stalk. The eye and stalk together are less than half as long as the peduncle of the superior antennae, and do not reach so far as the base of the filament of the inferior antennae. The basal joint of the superior antennae is excavated to receive the eye; there is a blunt recumbent tooth on the external edge of the excavation, near the base, and a second tooth, which is sharp, near the distal extremity; the inner edge is thickly set with hair, and bears a small tooth near the base. The third joint is shorter than the second, which is cylindrical, and the second than the first. The lower of the two filaments is very long, being about equal to the total length of the animal; whilst the other is compressed and very short, being much shorter than the carapace. The peduncle of the inferior antennae is cylindrical; and its single filament is slender and very long, being much longer than the animal. The antennal scale or lamellar palp extends beyond the peduncle of the superior antennae ; on its upper face there is a deep longitudinal groove near the outer margin, and a small tooth on the outer border near the extremity ; tbe inner border is fringed with hair. The joint to which this scale is attached is stout, and carries a strong tooth on its underside. The external jaw-feet are large and pediform ; they are more than twice as long as the multiarticulate ciliate palp, and they reach to the distal extremity of the lamellar palp of the inferior antennae. The next pair of jaw-feet are m u c h shorter, and are only half as long as their very elongate multiarticulate ciliate palps. The third joint of these jaw-feet is much compressed and broad. Each of the jaw-feet of the two outer pairs is furnished with a ciliate lamellar appendage at the base; the remaining three pairs of jaw-feet are short, and are furnished with several lamellar appendages. |
