158 the apodous holothurians 



Key to the Species of Molpadia. 



A. — Anchors wanting, or, if present, witli only 2 arms and associated witli a rosette of 3-8 

 jjerforated plates (plate xii, fig. 5). 

 B. — Phosphatic deposits present, often m abundance. 



C. — No true supporting rods, fusiform bodies or elongated perforated plates pres- 

 ent, though the discs of the tables nia}' be narrowed and drawn out into 

 a rod at each end. 

 D. — Tables of body often very irregular and distorted; sometimes wholly want- 

 ing, the disc seldom with more than S holes (those in the tail may have 

 20-30 holes). 

 E. — Tables with a more or less distinct disc, having 3-8 or more (usually 

 3-6) holes, often with irregular outline and marginal projections 

 (plate X, fig. r4). 

 F. — Tables of moderate size, the disc 90-350 ^ in diameter, usually 

 with only one spire. 

 G. — Tables often wanting in skin of body, present in tail ; disc 

 cjuite asymmetrical; spire of moderate height and 

 often with teeth or branches at top. 



Discs of tables in tail narrowed and elongated, the 

 ends drawn out into rods; spire usually of a single 



rod (plate x. fig. 14) oolitica 



Discs of tables not specially narrowed nor elongated; 



spire very irregular concolor 



GG. — Tables present in skin of body ; disc rather symmetrical, 

 with 3-6 or more holes; spire high (plate x, fig. 15; plate 

 xn, fig. 15). 



Discs of tables in tail not specially narrowed nor with 



numerous holes intermedia 



Discs of tables in tail somewhat narrowed and drawn 

 out at the ends, with numerous (10-30) holes (plate 



X, fig. 15c) andamanensis 



FF. — Tables very small, the disc less than 70 n in diameter, often 

 with 3 or 4 small, incomplete spires (plate x. fig. 16). 



SIMILI.S 



EE. — Tables of body less regular, often without distinct disc or spire, or 



with the rods composing the disc not united at their outer ends. 



F. — Tables of the body-wall over 150 ^u. across, with a disc composed 



of 6 or more slender diverging rods usually not united at their 



outer ends affinis 



FF. — Ta,bles much smaller, not provided with such a disc. 



Body tables more or less circular, about 60-70 fi in diameter ; 

 caudal tables well formed, with conspicuous spire, .roretzii 

 Body tables very irregular, 00-100 /x across; caudal tables not 

 specially different (plate xrii. figs. 15 and 16).. . .amorpha 

 DD. — Tables more regular, with very high spire, and the disc more or less cir- 

 cular, with 13-40 holes turgida 



CO. — Supporting rods, fusiform bodies, or elongated perforated plates present, at least 



in the tail (plate xi. figs. 6, 7, 8, and 13). 



D. — Fusiform bodies rod-like, usually with narrow, rounded, unp(>rforated, and 



undivided ends, occurring all over the body, sometimes flattened and 



widened in the tail musculus 



