NO. 3 DEICHMANN: HOLOTHURIOIDEA; PARTI, DENDROCHIROTA 109 



Remarks. — The genus has been established to accommodate some of 

 the species which have numerous buttons and distinct posterior prolonga- 

 tions on the radials. For the present 2 species from the West Indian 

 waters and 3 from the Panamic region are placed in the genus. Of these 

 latter, one may possibly deserve a genus of its own. No attempt has been 

 made to discuss the various East Indian species with similar spicules that 

 possibly belong in the genus. 



Key to the Species of Neothyone Kxown from the 

 Panamic Waters 



1. Spicules large buttons, faintly knobbed; external layer of but- 

 tons with strongly spinous handle. Feet with stout supporting 



tables with well-developed spire 



1. Neothyone gibber (Selenka) 



1. Spicules smaller or larger buttons strongly knobbed; external 

 layer of buttons with few spines on the handle (often lost in 

 older individuals) or transformed into baskets (the button 

 itself is almost smooth with long delicate projections on the ex- 

 ternal side uniting into a delicate reticulum) 2 



2. Feet with large smooth supporting rods with no trace of spire 

 (except in some of the dorsal appendages). External layer of 

 smooth buttons modified into baskets with the external side 

 covered by a delicate reticulum; these deposits are apparently 



retained throughout the animal's life 



2. Neothyone panamensis (Ludwig) 



2. Feet with curved, stout supporting tables with a varying 

 amount of spire; spire often large and deformed in dorsal ap- 

 pendages; older individuals may lack spire completely, but 

 often one side is expanded and lobate. External layer of buttons 

 often with a few spines on the handle but this type is often rare 

 or lacking in older individuals; often a few concave buttons 



with marginal spines form a simple type of baskets 



3. Neothyone gibbosa, new species 



1. Neothyone gibber (Selenka) 

 Plate 20, Figs. 1-9; text figure 5 



Stolus gibber Selenka, 1867, p. 356. 



Thyone gibber Semper, 1868, p. 66. — Theel, 1886, p. 139. — Deichmann, 

 1936, p. 64 (passim). 



