_mp´_ = smaller marginal pockets, in Tripedalia. _mst_ = muscle of stock of sensory club. _mt_ = muscle at base of tentacle. _n_ = nerve. _nc_ = network cells, in sensory club. _nf_ = nerve fibres. _nm_ = nematocyst. _nst_ = nerve of stalk of sensory club. _osn_ = outline of sensory niche. _p_ = perradius. _pe_ = pedalium. _ph_ = phacellus. _pr_ = proboscis. _r_ = reproductive organ. _rc_ = remains of concretion. _rcl_ = radial canal. _rg_ = radial ganglion. _rm_ = radial muscle. _rn_ = radial nerve. _rns_ = root of nerve of sensory club. _rs?_ = remains of stalk (?) of sensory organ. _rt_ = retina. _s_ = stomach. _sc_ = bell cavity. _scl_ = sensory club. _scn_ = supporting cell of nerve. _se_ = sensory epithelium. _sh_ = shrinkage space. _sl_ = stalk of lens. _sla_ = supporting lamella. _sn_ = sensory niche. _so_ = sensory organ in proboscis of Tripedalia. _sp_ = stomach pocket. _sph_ = stalk of phacellus. _ss_ = stalk of sensory organ, in proboscis. _st_ = stalk of sensory club. _su_ = suspensorium. _sub_ = subumbrella. _tl_ = lateral tentacle. _tm_ = median tentacle. _v_ = velarium. _va_ = vacuole. _vb_ = vitreous body. _vc_ = velar canals. _ve_ = edge of velarium. _vfs_ = visual fibres, according to Schewiakoff. _vg_ = valve of gastric ostium. _vl_ = vascular lamella. _vlc_ = vascular lamella connecting _vls_ with _vlm_. _vlm_ = vascular lamella of margin. _vls_ = vascular lamella of sensory niche. _vlst_ = vascular lamella of sensory niche at base of stalk. _wc_ = wandering cells. _w-x-y-z_ = successive levels of Figs. 40-43 on Fig. 5. DESCRIPTION OF FIGURES. Fig. 1. Charybdea Xaymacana, from one of the four interradial sides. Fig. 2. The same from above. Fig. 3. The same from below, the four tentacles cut off. Fig. 4. The same cut in halves vertically (or radially) through a perradius. Fig. 5. The same out in halves vertically (or radially) through an interradius. Figs. 6-16. Diagrams of horizontal (or transverse) sections through C. Xaymacana at successive levels. Fig. 17. Tripedalia cystophora, from one of the four interradial sides. Fig. 18. The same from below. Fig. 19. The same cut in halves vertically through a perradius. Fig. 20. The same cut in halves vertically through interradius. Figs. 21-30. Diagrams of horizontal sections through T. cystophora at successive levels. (The following are of Charybdea, except when specially stated otherwise.) Fig. 31. Horizontal section through the suspensorium. Fig. 32. Diagram of a gastric ostium seen from the stomach side. Fig. 33. Diagram of a vertical section through a gastric ostium.