On the other hand, the two limbless segments that precede the caudal furca are decidedly non-malacostracan.
Not more than thirteen caudal vertebrae.
Ce, Cerebral arteries; sp, supra - spinal or medullary artery; c, caudal artery; 1, lateral anastomotic artery of Limulus.
An, Orifice within which the caudal a, Movable (hinged) sclerite (sosegments are withdrawn.
The caudal vertebrae vary from a rudimentary condition in the guinea-pig to a great size in the jumping-hare and prehensile-tailed porcupines.
In Asymmetron the caudal region is remarkable for the curious elongation of the notochord, which is produced far beyond the last of the myotomes.
The development of its scutes and spines varies exceedingly, and specimens may be found without any lateral scutes and with short spines, others with only a few scutes and moderately sized spines, and again others which possess a complete row of scutes from the head to the caudal fin, and in which the fin-spines are twice as long and strong as in other varieties.
A long dorsal fln, high and pointed anteriorly, runs along nearly the whole length of the back; the caudal is strong and deeply cleft.
The keel of the ventral fin is continued past the anus into the expanded caudal fin, and so it happens that the anal opening is displaced from the middle line to the left side of the fin.
Aquatic larvae with caudal leaf-gills or with rectal tracheal system.