SEA OAT the dorsal cord is continuous, with cartilaginous neural arches and transverse processes; the skull is short and rounded, produced on each side into a process to which the lower jaw is connected instead of to an o quadratum ; the upper jaw and palate are fused with the skull, without traces of suture; the upper jaw has four broad plates or teeth, and the lower two ; the eyes very large and without lids; nasal cavities very large and convoluted, opening on the under side of the snout in front of the mouth, which is small ; the branchiae are not fixed by their outer margin, and are covered by a small operculum, adhering to the hyoid arch, with only a single aperture on each side behind the head, communicating interiorly with five branchial sacs opening separately into the pharynx ; there is no air bladder, and the in- testine has a spiral valve. The skin is covered with placoid granules ; between the eyes is a fleshy club-shaped process, with serrated edge and ending in a spine, which somewhat resem- bles a crown, and has given rise to one of its popular names, "the king of the herrings." The ventrals are abdominal, the anal small, the pectorals powerful, and the tail heterocercal ; the anterior dorsal is short, triangular, with a strong spine for the first ray, and is placed over the pectorals. They are oviparous, the large eggs being enclosed in a leathery capsule ; the males have trifid claspers. The northern sea cat (chimcera monstrosa, Linn.) has a conical snout, the dorsals contiguous and reaching to the end of the tail, which is prolonged into a slender filament; the body is elongated and shark-like ; the eyes have a greenish pupil sur- rounded by a white iris, and they shine, espe- cially at night, like cats' eyes, whence the com- mon ^jame; the color is silvery with brown spots ; the tail is nearly as long as the body. It attains a length of 3 or 4 ft., and is found in the North sea and northern Atlantic, where it pursues the shoals of herring and other mi- SEA CUCUMBER 727 Northern Sea Cat (Chimsera monstrosa). gratory fish ; it also feeds on jelly fishes and crustaceans. The flesh is tough, but the Nor- wegians use the eggs as food, and employ the oil of the liver in diseases of the eyes and for wounds. In the southern sea cat (callorhynchut auatralis, Gronov.) the snout ends in a gristly appendage, bent backward at the end so as to resemble a hoe ; the anterior dorsal is very far forward over the pectorals, the second over the ventrals and reaching to the caudal, and the tail does not end in a filament. It is of about the same size as the northern animal, and silvery, tinged with yellowish brown. SEA COW. See MANATEE. SEA CUCUMBER, one of the popular names of the holothuria, the highest order of the echinoderms, which are the highest class of ra- Sea Cucumber (Holothuria lutea). diated animals ; the name is derived from their generally elongated and more or less cylindri- cal and warty form ; they are also called sea slugs from their vermicular mode of creeping. The body is rather soft, with a leathery skin sometimes furnished with calcareous plates or granules without spines ; the mouth is at one end and the cloacal opening at the other, the former surrounded by branching and retractile tentacles supported on an osseous ring which forms the rudiment of an internal skeleton; the ambulacra (feet) or suckers are arranged usually in longitudinal rows on the sides of the body, alternating with spaces having no such apparatus, and corresponding to the spiny rows of star fishes and sea urchins; motion is effected principally by these suckers, the mouth for- ward. By the introduction or ejection of wa- ter at the posterior extremity the body may be made to assume great variations in length and width, and the general appearance externally is more that of an annelid than a radiate. Some of the genera (as synapta) have cutaneous an- chor-like hooks by which they attach them- selves, each inserted obliquely under a small subcutaneous scale perforated by a canal. The muscular layer under the skin is very thick, and so powerful in its constrictions that the animal can discharge all its viscera through the
