1918 Bush: on Echinoderms 41 



sole only; upper surface marked by large conical dermal projections; 

 mouth terminal; tentacles 15, much branched; color dark red. — Numerous, 

 in shallow and deep water. 



Genus Psolus 

 Small, chiton-like forms with a well-developed ventral creeping sole; 

 dorsal surface without ambulacral appendages, often with calcareous scales. 



1. Psolus chitonoides Clark. 



Small, about 30 mm. long and 20 mm. wide, chiton-like; dorsal surface 

 arched, covered with man}' firm granulated plates ; these plates varying 

 in size, largest ones on upper part ; dorsal ambulacral appendages none ; 

 mouth dorsal, anterior, surrounded by 10 tentacles; ventral sole well devel- 

 oped, depressed below edge of shell ; tube feet arranged in 2 to 4 rows 

 around the margin of the sole, a fairly well defined double row down the 

 middle of sole, and a single row of smaller imperfect tube feet close to the 

 margin on the under side of the marginal dorsal plates. Color red. — 

 Not numerous, at tide line. 



ORDER APODA 



KEY TO GENERA 



A. Worm-like ; semi-transparent. 



B. Calcareous deposits in form of anchors and plates, not forming 

 dots on skin. Leptosynapta (p. 41) 



BB. Calcareous deposits in form of wheels, forming dots on skin. 



Chiridota (p. 42) 

 AA. Not worm-like, bod}' tapering to a tail; not transparent. 



Caudina (p. 42) 



Genus Leptosynapta 



Forms small, delicate, worm-like, skin almost transparent showing 



muscle bands and organs; tentacles 10 to 13, pinnate, with 3 to 7 digits 



on each side ; calcareous deposits of various shapes in body-wall and 



tentacles. Burrowing in mud or sand at tide line and in deep water. 



1. Leptosynapta inhaerens (0. F. Miiller) Verrill. 



HolotJmria inhaerens O. F. Miiller; Chiridota pinnata Grube; Synapta 

 inhaerens Rathke; Synapta duvernaea Quatrefages ; Holothuria flava 

 Rathke; Synapta hensloxcana Gray; Synapta tenuis Ayres; Synapta ayrcsii 

 Selenka; Synapta gracilis Selenka ; Synapta albicans Selenka; Letosynapta 

 girardii Verrill; Leptosynapta tenuis Verrill. 



Small, 40 to 100 mm. long; white or yellowish with perhaps a reddish 

 tinge; tentacles 12, with 5 to 7 pairs of digits j)iniiatt'ly arranged; calca- 

 reous deposits rod-like, dumb-bell-shaped or rounded in tentacles, anchors 

 attached to perforated ])lates in body wall ; calcareous ring well dcvel- 



