NO. 3 DEICHMANN : HOLOTHURIOIDEA ; PART I, DENDROCHIROTA 141 



band along the midventral ambulacrum. Dorsal side with numerous im- 

 bricating scales, about 14 between oral and anal apertures in the largest 

 individual. Dorsal feet few, rudimentary, easily overlooked. 



Spicules in sole var^^ing from 4-holed buttons to irregular, perforated 

 plates with marginal knobs and occasionally a few knobs near the center. 

 Feet with end plate and perforated rods and plates. Dorsal side with 

 scales, delicate hourglass-shaped cups of lacelike structure and huge tow- 

 ers which in the older individuals are partly resorbed from the tip, so 

 that they become shorter, thimblelike. Feet apparently without end plate; 

 walls supported by cui-ved squarish plates with 4 central holes and a varj^- 

 ing number of smaller marginal ones. Tentacles with heavy plates and 

 rods ; in the branches delicate plates and rods ; apparently no rosettes. 



Type. — Holotype, AHF no. 37, 19 paratypes. 



Type locality. — Station 521-36, Agua Verde Bay, L. Calif., north of 

 anchorage, 5-10 fms., February 27, 1936. 



Distribution. — Gulf of Calif, to Ecuador. 



Depth. — From 5-165 fms. 



Specimens examined. — The following individuals from the Allan 

 Hancock Expeditions: 

 213-34. La Plata Island, Ecuador, dredging north of anchorage, rocky, 



7-10 fms., February 10, 1934, 3 small specimens. 

 521-36. Agua Verde Bay, L. Calif., Mex., 5-10 fms., February 27, 



1936, 5 small specimens. 

 529-36. Off San Francisquito Bay, L. Calif., Mex., 165 fms., March 1, 



1936, 12 large specimens. 

 854-38. Gorgona Island, Colombia, north of Island, 40-60 fms., Febru- 

 ary 24, 1938, 7 large and 2 small specimens. 



Remarks. — A well-defined species which is easily recognized. 



Genus 2. PSOLIDIUM Ludwig, 1887 



Diagnosis. — Small forms (sole few cm. long) ; sole sharply set off; 

 with feet along the edges and few or many in the midventral ambulacrum ; 

 dorsal side with numerous imbricating scales, and a vaiying number 

 of tube feet which pass out through some of the scales. Spicules in sole 

 plates or buttons, smooth to knobbed, usually also an external layer of 

 small deep cups. Feet with end plate and supporting plates or rods. Dorsal 

 side usually with an external layer of cups (possibly lacking in some 

 species) ; besides grain or towers (more or less completely reduced with 



