The aim was to provide a comprehensive ultrastructural account of the spinous body tegument and closely associated systems.
The upper limb bears a moderately developed posterior spinous process.
A short spinous latero-ventral appendage is situated slightly more posteriorly.
The apical plasma membrane was generally smooth over the spinous regions, although where spines became less frequent or absent the surface was often pimpled (fig. 15, p).
The spinous dorsal fin is placed above the pelvic fins and is normally retracted in a groove.
The fins are dusky with the exception of the spinous dorsal fin which is pale to dark dusky.
They have no spinous dorsal fin, absent or reduced scales, sandpapery denticles on various areas of the body, and a reduced gill opening.
The carina is modified into spinous processes on last three whorls.
