VIII 



ECHINODERMA TA S YSTEMA TIC RE VIE W 



287 



Family 4. Dendrochirot*. 



Tube-feet present. Mouth dorsal or terminal. Anus also often dorsal. Body 

 cylindrical, or pentagonal, or with a distinctly marked creeping sole. 10-30 arbor- 





FIG. 227. Psolus ephippifer, 

 young female, from the dorsal side 

 (after Theel). 1, Oral valves; 2, 

 anus. 



FIG. 226. Cuoumaria planci (original). 1, The 

 two smaller ventral oral tentacles ; 2, mouth ; 

 3, anus. 



escent tentacles, often of unequal size. Tentacular 

 ampullre not distinct. Not infrequently more than 

 one stone canal. Retractor muscles well developed. 

 Respiratory trees present ; Cuvier's organs only 

 occasionally found. Cucumaria (Fig. 226), Thyone, 

 PhyUophorus, Colochirus, Thdelia, Psolus (Figs. 227 

 and 228), Rhopalodina. 



Family 5. Molpadiidse. FIG. 228. Psolus ephippifer, 



female, dorsal aspect (after Theel). 



Tube-feet wanting. Mouth terminal. The pos- i, Oral valves, opened ; 2, anus ; 

 terior end of the cylindrical body often narrowed to 3, oral tentacles ; 4, dorsal cal- 

 a shorter or longer tail-like piece, which is more or careous scales, 

 less distinct from the trunk. 15 tubular or digitate 



tentacles normally present. Tentacular ampullae present. A single stone canal. 

 Retractor muscles distinct only in the genus Molpadia. Respiratory trees present. 

 Cuvier's organs almost always absent. Moljjadia, Caudina, Trochostoma, An- 

 kyrodcrma. 



